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ASME Conference Presenter Attendance Policy and Archival Proceedings

2011;():i. doi:10.1115/DETC2011-NS3.
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This online compilation of papers from the ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2011) represents the archival version of the Conference Proceedings. According to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in the ASME Digital Library and may not be cited as a published paper.

Commentary by Dr. Valentin Fuster

2011 ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications

2011;():3-12. doi:10.1115/DETC2011-47139.

Verification of software for embedded systems is crucial for ensuring a product’s integrity. Formal approaches like static analysis and model checking are gaining momentum in this context. To make an exhaustive examination of the system’s state space tractable in practice, these methods perform an abstraction and over-approximation of the possible behavior. As a side-effect, however, this leads to “false negatives” -property violations that exist only in the model and not on the real system. Ruling out such spurious property violations by manual valuation is a tedious and error-prone process. This paper reports on the concepts and design of a hardware unit to support the identification of false negatives. Our approach has several advantages: (i) It works on microcontroller binary code, thus avoiding the need for availability of high-level source code, and covering compiler bugs as well, (ii) Moving the verification directly to the target platform rules out modeling errors. (iii) The cases suspected to lead to spurious property violations can serve as very efficient test cases for a specific implementation later on. We illustrate principle and benefits of the proposed approach by a worked example.

Commentary by Dr. Valentin Fuster
2011;():13-19. doi:10.1115/DETC2011-47843.

According to labor market needs even fresh graduates from undergraduate programs have to have not only profound knowledge but also extensive practical experiences especially when it comes to software design for Embedded Computing Systems. Didactic approaches like problem-based learning and project-based learning with a high degree of hands-on training using state of the art hardware, software, and tools have proven to achieve this learning outcome. Even though hands-on training using industry relevant equipment works fine with full-time students, the desired practical skills have to be obtained in a different way with part-time or distance-learning students. This is because of the significantly reduced training hours at dedicated university labs. This paper focuses primarily on a concrete setup and mix of dedicated learning infrastructures (“Remote-Lab” and “Hardware/Software Co-Simulation”) suitable for courses dealing with Embedded Systems (Software) Design to support students, participating in part-time or distance-learning degree programs, in developing their required skills.

Commentary by Dr. Valentin Fuster
2011;():21-27. doi:10.1115/DETC2011-47910.

The ever increasing complexity of embedded systems is driving the change in embedded software development from traditional approaches to model-based design methodology. The model-based design approach provides a number of benefits such as reducing software development time and cost, improving software quality through computationally intensive modeling, and real-time verification. This paper presents model-based embedded system design using a rapid prototyping system called Mototron. Models for individual components and the control strategies are developed in a simulation environment with MotoHawk, Simulink, and Stateflow software tools. The developed control algorithms and parameters are then tested using a calibration tool (MotoTune) that is connected to embedded system hardware. An electronic throttle control example is given in the paper to illustrate the major steps of model-based embedded system design using Mototron system.

Commentary by Dr. Valentin Fuster
2011;():29-38. doi:10.1115/DETC2011-47928.

In most embedded, real-time applications, processes need to satisfy various important constraints and dependencies, such as release times, offsets, precedence relations, and exclusion relations. Embedded, real-time systems with high assurance requirements often must execute many different types of processes with such constraints and dependencies. Some of the processes may be periodic and some of them may be asynchronous. Some of the processes may have hard deadlines and some of them may have soft deadlines. For some of the processes, especially the hard real-time processes, complete knowledge about their characteristics can and must be acquired before run-time. For other processes, prior knowledge of their worst case computation time and their data requirements may not be available. It is important for many embedded real-time systems to be able to simultaneously satisfy as many important constraints and dependencies as possible for as many different types of processes as possible. In this paper, we discuss what types of important constraints and dependencies can be satisfied among what types of processes. We also present a method which guarantees that, for every process, no matter whether it is periodic or asynchronous, and no matter whether it has a hard deadline or a soft deadline, as long as the characteristics of that process are known before run-time, then that process will be guaranteed to be completed before predetermined time limits, while simultaneously satisfying many important constraints and dependencies with other processes.

Commentary by Dr. Valentin Fuster
2011;():39-45. doi:10.1115/DETC2011-48634.

Reconfiguration-Based Fault-Tolerance is one approach for developing dependable safety-critical embedded applications. This approach, compared to traditional hardware and software redundancy, is a promising technique that may achieve the required dependability with a significant reduction in cost in terms of size, weight, price, and power consumption. Reconfiguration necessitates using proper checkpointing protocols to support state reservation and task migration. One of the most common approaches is to use Communication Induced Checkpointing (CIC) protocols, which are well developed and understood for large parallel and information systems, but not much has been done for resource limited embedded systems. This paper implements four common CIC protocols in a resource constrained distributed embedded system with a Controller Area Network (CAN) backbone. An example feedback control system implementation is used for a case study. The four implemented protocols are described and performances are contrasted. The paper compares the protocols in terms of network bandwidth consumptions, CPU usages, checkpointing times, and checkpoint sizes in additional to the traditional measures of forced to local checkpoint rations and total number of checkpoints.

Commentary by Dr. Valentin Fuster
2011;():47-52. doi:10.1115/DETC2011-48908.

A heterogeneous macro-model for power extraction of the Network-on-Chip router at system level is proposed, with higher accuracy to overcome the shortcoming of existing architecture-level power simulators, which is aimed to evaluate the network performance rapidly and guide the communication structure design. Each module of the router is modeled by different methods according to different characteristics. The input/output ports, the routing algorithm and the crossbar switch are established by multiple linear regression because of their single data flow state. The arbiter is established based on BP neural network due to its numerous states. Several experiments with different traffic loads and input sequences are carried out to verify the power model. Experimental results show that our power model is higher speed over the gate-level simulation, and the average estimation error is 5.0%. As a case study, we use the proposed model to evaluate the performance of different core mappings for H.264 decoder in system-level low power design.

Topics: Modeling , Networks
Commentary by Dr. Valentin Fuster
2011;():53-58. doi:10.1115/DETC2011-48912.

The reliable transfer in Network on Chip can be guaranteed by crosstalk avoidance and error detection code. In this paper, we propose a joint coding scheme combined with crosstalk avoidance coding with error control coding. The Fibonacci numeral system is applied to satisfy the requirement of crosstalk avoidance coding, and the error detection is achieved by adding parity bits. We also implement the codec in register transfer level. Furthermore, the schemes of codec applying to fault-tolerant router are analyzed. The experimental result shows that “once encode, multiple decode” scheme outperforms other schemes in trade-off of delay, area and power.

Commentary by Dr. Valentin Fuster
2011;():59-64. doi:10.1115/DETC2011-48957.

This work describes a new methodology for the purpose of remote testing, debugging and maintenance of networked electronic and mechatronic systems which makes use of the IEEE 1588 high-precision clock synchronization protocol. After the underlying concepts of IEEE 1588 are briefly sketched, the paper describes how functionalities like testing, debugging and maintenance can benefit from a network-wide notion of time as provided by the IEEE 1588 standard. An implementation of the IEEE 1588 protocol with support for test, debug and maintenance as well as links to the integration of the proposed concept into existing tools are presented. Further, the proposed approach is discussed under consideration of recent standardization efforts. Finally, a case study from the area of automotive electronics is described.

Topics: Maintenance
Commentary by Dr. Valentin Fuster
2011;():65-74. doi:10.1115/DETC2011-48981.

While the dynamic voltage scaling (DVS) techniques are efficient in reducing the dynamic energy consumption for the processor, varying voltage alone becomes less effective for the overall power reduction as the leakage power is growing rapidly, i.e., five times per technical generation as predicted. On the other hand, Quality of Service (QoS) is also a primary concern in the development of today’s pervasive computing systems. In this paper, we study the problem of minimizing the overall energy consumption for soft real-time systems while ensuring the QoS-guarantee. In our research, the QoS requirements are deterministically quantified with the (m,k)-constraints, which require that at least m out of any k consecutive jobs of a task meet their deadlines. Two approaches are proposed in this paper. One statically determines the mandatory jobs that have to meet their deadlines in order to satisfy the (m,k)-constraints, and the other one does so dynamically. Moreover, we present efficient scheduling techniques to reduce the overall energy by procrastinating the execution of mandatory jobs and thus to merge the idle intervals. The simulation results demonstrate that our proposed techniques significantly outperformed previous research in both overall and idle energy reduction while providing the (m,k)-guarantee.

Commentary by Dr. Valentin Fuster
2011;():75-84. doi:10.1115/DETC2011-47053.

This paper presents practical aspects of tuning and implementation of Fractional-Order Controllers (FOC). In the article are presented tuning, auto-tuning and self-tuning methods for the FOC. As the FOC are considered fractional PID controllers, the CRONE controller and fractional-order lead-lag compensators. As implementation techniques are described the FIR and FIRforms of approximation methods, which can be easily implemented in microprocessor devices such as for example the PLC, IPC, etc. The possibility for analogue implementation of such kind of controllers is also mentioned. An example of practical implementation of the FOC together with all problems and restrictions is shown as well.

Commentary by Dr. Valentin Fuster
2011;():85-94. doi:10.1115/DETC2011-47071.

In this paper, a class of fractional advection-dispersion models (FADM) is investigated. These models include five fractional advection-dispersion models: the immobile, mobile/immobile time FADM with a temporal fractional derivative 0 < γ < 1, the space FADM with skewness, both the time and space FADM and the time fractional advection-diffusion-wave model with damping with index 1 < γ < 2. They describe nonlocal dependence on either time or space, or both, to explain the development of anomalous dispersion. These equations can be used to simulate regional-scale anomalous dispersion with heavy tails, for example, the solute transport in watershed catchments and rivers. We propose computationally effective implicit numerical methods for these FADM. The stability and convergence of the implicit numerical methods are analyzed and compared systematically. Finally, some results are given to demonstrate the effectiveness of our theoretical analysis.

Commentary by Dr. Valentin Fuster
2011;():95-104. doi:10.1115/DETC2011-47107.

In this paper, we are concerned with the existence of solutions for a class of nonlinear fractional functional differential equations with boundary value conditions. Some existence results of solutions are obtained. Our analysis relies on some fixed point theorems. Finally, some examples are presented to illustrate the main results.

Commentary by Dr. Valentin Fuster
2011;():105-114. doi:10.1115/DETC2011-47204.

The equivalent same-order system for multi-rational-order fractional differential system with Caputo derivative is studied. With the relationship between Caputo derivative and generalized fractional derivative, we can change the multi-order fractional differential system whose fractional order is rational into a much higher-dimensional fractional differential system with the same order lying in (0,1). Based on the equivalent results, the stability analysis of any multi-rational-order fractional differential system is given. Finally, several examples are provided to illustrate the results in this paper.

Topics: Stability
Commentary by Dr. Valentin Fuster
2011;():115-122. doi:10.1115/DETC2011-47250.

This paper provides an experimental validation of the required time-varying initialization response for fractional-order systems. The experiment considers thermal conduction in a long aluminum rod, whose thermal impedance can be approximated as a half-order integral. Experimental results using seven different history functions are compared with theoretical predictions. The experimental results compare well with the expected theoretical predictions. Deviations from the theoretical predictions are discussed.

Commentary by Dr. Valentin Fuster
2011;():123-128. doi:10.1115/DETC2011-47284.

This paper addresses the use of multidimensional scaling in the evaluation of fractional system approximations. Algorithms are analysed based on the time response of the closed loop system under the action of a reference step input signal. Two alternative performance indices, based on the time and frequency domains, are tested. The numerical experiments demonstrate the feasibility of the proposed methodology.

Commentary by Dr. Valentin Fuster
2011;():129-136. doi:10.1115/DETC2011-47286.

The CRONE CSD methodology proposes to design robust controllers by using fractional order operators. A Matlab toolbox has been developed based on this methodology and is freely available for the international scientific and industrial communities. This paper presents both the methodology and the toolbox. The design of two robust controllers for irrigation canals show how the toolbox can be used.

Commentary by Dr. Valentin Fuster
2011;():137-141. doi:10.1115/DETC2011-47317.

A new fractional derivative of complex Grüwald-Letnikov type is proposed and some properties are studied. The new definition incorporates both the forward and backward Grüwald-Letnikov and other fractional derivatives well known. Several properties of such generalized operator are presented.

Commentary by Dr. Valentin Fuster
2011;():143-147. doi:10.1115/DETC2011-47374.

The paper presents the results of modeling the heat transfer process in heterogeneous media with the assumption that part of the heat flux is dispersed in the air around the beam. The heat transfer process in solid material (beam) can be described by integer order partial differential equation. However, in heterogeneous media it can be described by sub- or hyperdiffusion equation which results in fractional order partial differential equation. Taking into consideration that the part of the heat flux is dispersed into the neighbouring environment we additionally modify the main relation between heat flux and the temperature, and we obtain in this case the heat transfer equation in the new form. This leads to the transfer function which describes the dependency between the heat flux at the beginning of the beam and the temperature at the given distance. The article also presents the experimental results of modeling real plant in the frequency domain basing on the obtained transfer function.

Commentary by Dr. Valentin Fuster
2011;():149-154. doi:10.1115/DETC2011-47392.

Noises are usually assumed to be Gaussian so that many existing signal processing techniques can be applied with no worry. However, in many real world natural or man-made systems, noises are usually heavy-tailed. It is increasingly desirable to address the problem of finding an opportune filter function for a given input noise in order to generate a desired output noise. By filtering theory, the probability density function of the output noise can be expressed by the integral of the product of the density of the input noise and the filter function. Adopting Mellin transformation rules, the Mellin transform of the unknown filter is determined by the Mellin transforms of the known density of the input noise and the desired density for the output noise. Finally, after the inversion, the Mellin-Barnes integral representation of the filter function is derived. The method is applied to compute the filter function to convert a Levy noise into a Gaussian noise.

Commentary by Dr. Valentin Fuster
2011;():155-161. doi:10.1115/DETC2011-47395.

A new method for the solution of linear constant coefficient fractional differential equations of any commensurate order based on the Laplace transforms of the fractional meta-trigonometric functions and the R-function is presented. The new method simplifies the solution of such equations. A simplifying characterization that reduces the number of parameters in the fractional meta-trigonometric functions is introduced.

Commentary by Dr. Valentin Fuster
2011;():163-168. doi:10.1115/DETC2011-47396.

This paper derives the time-varying initialization function for the Caputo derivative with order between zero and one. The derivative is redefined to include this initialization function. Then, the Laplace transform for the redefined Caputo derivative is determined which corrects (supplants) that given for the derivative in the literature and properly accounts for time-varying initialization effects.

Commentary by Dr. Valentin Fuster
2011;():169-178. doi:10.1115/DETC2011-47408.

A high speed algorithm for computing fractional differentiations and fractional integrations in fractional differential equations is proposed. In this algorithm the stored data is not the history of the function to be differentiated or integrated but the history of the weighted integrals of the function. It is shown that, by the computational method based on the new algorithm, the integration time only increases in proportion to n log n, different from n2 by a standard method, for n steps of integrations of a differential integration.

Commentary by Dr. Valentin Fuster
2011;():179-184. doi:10.1115/DETC2011-47415.

Fatigue cracking of the rotor shaft is an important fault observed in rotating machinery of key industry, which can lead to catastrophic failure. Nonlinear dynamics of a cracked rotor system with fractional order damping is investigated by using a response-dependent breathing crack model. The four-th order Runge-Kutta method and ten-th order CFE-Euler (Continued Fraction Expansion-Euler) method are introduced to simulate the proposed system equation of fractional order cracked rotors. The effects of derivative order of damping, rotating speed ratio, crack depth, orientation angle of imbalance relative to the crack direction and mass eccentricity on the system dynamics are demonstrated by using bifurcation diagram, Poincare map and rotor trajectory diagram. The results show that the rotor system displays chaotic, quasi-periodic and periodic motions as the fractional order increases. It is also found that the imbalance eccentricity level, crack depth, rotational speed, fractional damping and crack angle all have considerable influence on the nonlinear behavior of the cracked rotor system.

Commentary by Dr. Valentin Fuster
2011;():185-192. doi:10.1115/DETC2011-47444.

Consideration of the transient response is one of the key topics in control system design for time delay systems. In this paper, an efficient method to control the transient response of the first order plus time delay stable (FOPTD) systems using the fractional-order PI (PIλ ) controllers is presented. The main characterization of the method is first to construct the global stability region in the (kp , ki )-plane for any fixed value of λ and then to obtain ts and Mp curves corresponding to special settling time and maximum overshoot values in this region. Finally, by intersection of these curves, the Dλ -stability region in the (kp , ki )-plane is found. Changing the value of λ in the range of (0, 2), a set of Dλ -stability regions is obtained. These regions involve the controller parameters providing the closed loop settling time and maximum overshoot specifications together in the acceptable values. Therefore, the designer can easily decide to the selection of suitable values of kp , ki and λ. The simulation results indicate that the presented transient response control method is effective and practically useful in the analysis and control of the stable FOPTD systems by means of fractional-order PI controllers.

Commentary by Dr. Valentin Fuster
2011;():193-200. doi:10.1115/DETC2011-47552.

Fractional derivative stress-strain relations are derived for compressible viscoelastic materials based on the continuum mechanics. Several types of stress tensor and strain tensors are specified to describe the dynamics of continuous media. Consequently there are many equivalent expressions of stress-strain relations. If memory effect is not taken into account, these relations are equivalently transformed from one to another by suitable tensor operations. However, if memory effect is included in the mechanics of the materials, different types of stress-strain relations can be derived depending on the choice of the type of stress tensor, or equivalently the choice of the strain energy function. In this paper, several types of fractional derivative stress-strain relations are proposed.

Commentary by Dr. Valentin Fuster
2011;():201-210. doi:10.1115/DETC2011-47613.

Fractional order dynamics in physics, particularly when applied to diffusion, leads to an extension of the concept of Brownian motion through a generalization of the Gaussian probability function to what is termed anomalous diffusion. As MRI is applied with increasing temporal and spatial resolution, the spin dynamics are being examined more closely; such examinations extend our knowledge of biological materials through a detailed analysis of relaxation time distribution and water diffusion heterogeneity. Here the dynamic models become more complex as they attempt to correlate new data with a multiplicity of tissue compartments where processes are often anisotropic. Anomalous diffusion in the human brain using fractional order calculus has been investigated. Recently, a new diffusion model was proposed by solving the Bloch-Torrey equation using fractional order calculus with respect to time and space (see R.L. Magin et at, J. Magnetic Resonance, 190 (2008) 255–270). However effective numerical methods and supporting error analyses for the fractional Bloch-Torrey equation are still limited. In this paper, the space and time fractional Bloch-Torrey equation (ST-FBTE) is considered. The time and space derivatives in the ST-FBTE are replaced by the Caputo and the sequential Riesz fractional derivatives, respectively. Firstly, we derive an analytical solution for the ST-FBTE with initial and boundary conditions on a finite domain. Secondly, we propose an implicit numerical method (INM) for the ST-FBTE, and the stability and convergence of the INM are investigated. We prove that the implicit numerical method for the ST-FBTE is unconditionally stable and convergent. Finally, we present some numerical results that support our theoretical analysis.

Topics: Spacetime , Equations
Commentary by Dr. Valentin Fuster
2011;():211-217. doi:10.1115/DETC2011-47623.

In this paper we further develop Podlubny’s matrix approach to discretization of integrals and derivatives of arbitrary real order. Numerical integration and differentiation on a set of non-equidistant nodes is described and illustrated by several examples of numerical solution of fractional differential equations. In this paper, for the first time, we present a variable step length approach that we call “the method of large steps”, since it is applied in combination with the matrix approach for each “large step”. This new method is also illustrated by an example. The presented approach allows fractional order differentiation and integration of non-uniformly sampled signals, and opens the way to development of variable and adaptive step length techniques for fractional differential equations.

Commentary by Dr. Valentin Fuster
2011;():219-226. doi:10.1115/DETC2011-47633.

Riemann-Liouville and Caputo fractional derivatives are fundamentally related to fractional integration operators. Consequently, the initial conditions of fractional derivatives are the frequency distributed and infinite dimensional state vector of fractional integrators. The paper is dedicated to the estimation of these initial conditions and to the validation of the initialization problem based on this distributed state vector. Numerical simulations applied to Riemann-Liouville and Caputo derivatives demonstrate that the initial conditions problem can be solved thanks to the estimation of the initial state vector of the fractional integrator.

Commentary by Dr. Valentin Fuster
2011;():227-233. doi:10.1115/DETC2011-47696.

In this paper, an algebraic tuning rule is presented for fractional PI controllers to control first order plus dead-time processes. By using the performance map (PM) method, this tuning rule is derived in order to set the gain margin of the control system close to 3 and the phase margin close to 60 degrees. The robustness and performance of this tuning rule are compared with some well-known PI tuning rules. Simulation results are brought to demonstrate the effectiveness and robustness of this tuning formula against process dynamic uncertainties in comparison with the other tuning methods.

Commentary by Dr. Valentin Fuster
2011;():235-240. doi:10.1115/DETC2011-47699.

This paper is devoted to analysis of undamped oscillations generated by fractional order linear time invariant (LTI) systems. At first, the trajectories of marginally stable commensurate order systems are investigated. It is verified that we can not use the time-independent phase flow concept for this kind of systems. Also, the differences with the integer order case are highlighted. Then, it is shown that we can determine the Q-norm of the limit sets of a trajectory for these systems based on the Q-norm of the initial condition. Some numerical examples are brought to confirm the achievements of the paper.

Topics: Oscillations
Commentary by Dr. Valentin Fuster
2011;():241-250. doi:10.1115/DETC2011-47721.

We study the properties of fractional differentiation with respect to the reflection symmetry in a finite interval. The representation and integration formulas are derived for the symmetric and anti-symmetric fractional derivatives, both of the Riemann -Liouville and Caputo type. The action dependent on the left -sided Caputo derivatives of orders in range (1.2) is considered and we derive the Euler-Lagrange equations for the symmetric and anti-symmetric part of the trajectory. The procedure is illustrated with an example of the action dependent linearly on fractional velocities. For the obtained Euler-Lagrange system we discuss its localization resulting from the subsequent sym-metrization of the action.

Topics: Reflection , Equations
Commentary by Dr. Valentin Fuster
2011;():251-255. doi:10.1115/DETC2011-47731.

The neutron transport denotes the study of the motions and interactions of neutrons with materials. In given applications we need to know where neutrons are in an apparatus, what direction they are moving, and how fast they are going. In this manuscript the Legendre polynomial approximation method FN was applied to the one dimensional slab geometry neutron transport equation.

Commentary by Dr. Valentin Fuster
2011;():257-265. doi:10.1115/DETC2011-47734.

Fractional calculus has been successfully applied to characterize the rheological property of viscoelastic materials, however, geomaterials were seldom involved in fractional order constitutive models (FOCM), and the issue of first loading and then unloading is rarely discussed through fractional calculus. It is considered that all materials are arranged in a queue and ideal solid and Newtonian fluid are located at both ends of the queue in FOCM. On the basis of FOCM, stress-strain relation under the condition of first loading and then unloading, besides creep, stress-relaxation and loading of constant strain rate are obtained. The stress-strain relation is utilized to fit triaxial test results of geomaterials under the corresponding conditions. The comparison between the test and fitting results reveals that FOCM can reasonably describe the stress-strain, stress-time or strain-time characteristics of geomaterials, which shows that fractional calculus is a good tool to constitutive model research of geomaterials.

Commentary by Dr. Valentin Fuster
2011;():267-274. doi:10.1115/DETC2011-47769.

In previous studies of the second author mechanical wave motion on a viscoelastic material representative of biological tissue was analyzed. Compression, shear and surface wave motion in and on a viscoelastic halfspace excited by surface and subsurface sources were considered. It was shown that a fractional order Voigt model, in which the damping component, dependent on the first derivative of time, is replaced with a fractional element dependent on a derivative of time of fractional order between 0 and 1, resulted in closer agreement with experiment as compared with the conventional (integer order) models of Voigt and Zener. In the present study different materials and a wider range of viscoelastic models are considered. An algorithm to evaluate the frequency-dependent shear moduli of viscoelastic materials measuring the propagation of Rayleigh waves on the surface of the media is presented and viscoelastic models (both of integer and fractional order) are compared to experimental results. It is shown that, in the frequency range of interest (100–600 Hz), the use of the fractional order assumption improves the match of theory to experiment.

Commentary by Dr. Valentin Fuster
2011;():275-284. doi:10.1115/DETC2011-47835.

The article presents an approach for combining methods of recursive Bayesian estimation with models of dynamical systems with varying differentiation order. The work addresses the problem of explicit fractional order estimation and tracking by constructing an efficient Unscented Kalman filter, where the model order is directly estimated within an augmented state along with the variables of interest. The feasibility of the estimation method is assessed using a benchmark problem based on a simplified fractional neuron firing rate model and time-dependent differentiation order. The proposed technique is compared to an implicit method based on Interacting Multiple Model filtering and a computationally efficient method using a modification of the Ensemble Kalman filter. The performance with respect to different parameters and filter settings is analyzed and a corresponding discussion is provided.

Topics: Kalman filters
Commentary by Dr. Valentin Fuster
2011;():285-291. doi:10.1115/DETC2011-47842.

Most wind turbines installed have traditional architectures: double-fed asynchronous machine or direct drive with full conversion, both containing several levels of control composed of PI controllers. In our application, a robust 3rd-generation-CRONE controller is used to manage a planetary gearing ratio upstream of a synchronous generator directly connected to the grid. Thus, the speed of the low shaft is controlled and unlike other architectures, no system of power electronics is required for conversion. This CRONE approach is a robust control methodology based on fractional order differentiation.

Commentary by Dr. Valentin Fuster
2011;():293-302. doi:10.1115/DETC2011-47864.

Firstly the one-dimension digital fractional order Savitzky-Golay differentiator (1-D DFOSGD), which generalizes the Savitzky-Golay filter from the integer order to the fractional order, is proposed to estimate the fractional order derivative of the noisy signal. The polynomial least square fitting technology and the Riemann-Liouville fractional order derivative definition are used to ensure robust and accuracy. Experiments demonstrate that 1-D DFOSGD can estimate the fractional order derivatives of both ideal signal and noisy signal accurately. Secondly, the two-dimension DFOSGD is obtained from 1-D DFOSGD by defining a group of direction operators, and a new image enhancing method based on 2-D DFOSGD is presented. Experiments demonstrate that 2-D DFOSGD has very good performance on image enhancement.

Commentary by Dr. Valentin Fuster
2011;():303-310. doi:10.1115/DETC2011-47867.

The impulse response of a generalized fractional second order filter of the form (s2α + asα + b)−γ is derived, where 0 < α ≤ 1, γ > 0. The asymptotic properties of the impulse responses are obtained for two cases, and similar properties are shown for these two cases when we change the value of γ. It is shown that only when (s2α + asα + b)−1 has the critical stability, the generalized fractional second order filter (s2α + asα + b)−γ has different properties as we change the value of γ. Finally, numerical examples to illustrate the impulse response are provided to verify the proposed concepts.

Commentary by Dr. Valentin Fuster
2011;():311-321. doi:10.1115/DETC2011-47872.

First order plus time delay model is widely used to model systems with S-shaped reaction curve. Its generalized form is the use of a single fractional pole to replace the first order (single-time constant) model, which is believed to better characterize the reaction curve. Using time delayed system model with a fractional pole as the starting point, in this paper, designing fractional order controllers for this class of fractional order systems is investigated. The novelty of this paper is on designing the integer order PID and fractional order PI and [PI] controllers for these class of systems. The simulation and lab experimental results are both included to illustrate the effectiveness of the proposed tuning method. By comparing the results of PID controller, fractional order PI and [PI] controllers, the advantages of the fractional order controller are clearly demonstrated in the case of controlling the single fractional pole plants with constant time delay.

Commentary by Dr. Valentin Fuster
2011;():323-328. doi:10.1115/DETC2011-47878.

Electroencephalogram (EEG), the measures and records of the electrical activity of the brain, exhibits evidently nonlinear, non-stationary, chaotic and complex dynamic properties. Based on these properties, many nonlinear dynamical analysis techniques have emerged, and much valuable information has been extracted from complex EEG signals using these nonlinear analysis techniques. Among these techniques, the Hurst exponent estimation was widely used to characterize the fractional or scaling property of the EEG signals. However, the constant Hurst exponent H cannot capture the the detailed information of dynamic EEG signals. In this research, the multifractional property of the normal human sleep EEG signals is investigated and characterized using local Holder exponent H(t). The comparison of the analysis results for human sleep EEG signals in different stages using constant Hurst exponent H and the local Hölder exponent H(t) are summarized with tables and figures in the paper. The analysis results show that local Hölder exponent provides a novel and valid tool for dynamic assessment of brain activities in different sleep stages.

Commentary by Dr. Valentin Fuster
2011;():329-334. doi:10.1115/DETC2011-47880.

Median filtering, an effective non-linear signal enhancement technique, has been successfully used for the suppression of impulsive noise and extracting features from noisy signals. Although median filtering can effectively preserve the sharp changes in signals, some signal distortion may be introduced and some features of signals may be lost. In this research, we investigate the effects of median filtering on fractional processes which are characterized by the heavy-tailed distribution or the long-range dependence (LRD). The effects of median filtering on heavy-tailed distribution characteristic of α -stable processes, and on LRD property of long-range dependent processes are investigated, respectively. Besides, the effects of median filtering on both the heavy tailed distribution and the LRD properties of fractional autoregressive integrated moving average (FARIMA) with stable innovations time series are studied. The analysis results show that the heavy-tailed distribution and the LRD properties of fractional processes are evidently affected by median filtering.

Topics: Filtration
Commentary by Dr. Valentin Fuster
2011;():335-338. doi:10.1115/DETC2011-47953.

Fractional variational principles started to be one of the major area in the field of fractional calculus. During the last few years the fractional variational principles were developed within several fractional derivatives. One of them is the Hilfer’s generalized fractional derivative which interpolates between Riemann-Liouville and Caputo fractional derivatives. In this paper the fractional Euler-Lagrange equations of the Lagrangians with linear velocities are obtained within the Hilfer fractional derivative.

Commentary by Dr. Valentin Fuster
2011;():339-351. doi:10.1115/DETC2011-48016.

In this paper, the distinction between an operator’s historical initial condition function, the consequential initialization function of the operator, and the resulting initialization response of an entire system, is discussed. The single term and two-term differential equation results with constant history functions from earlier studies are reviewed. A three-term linear fractional-order differential equation with constant history function is studied next. This system is solved by using the proper Laplace transforms for the fractional-order derivatives. The paper then presents the initialization responses for multi-term linear fractional-order systems with commensurate orders that have had arbitrarily-long constant displacements in negative time. Results for short-times and for long-times are provided. These results are obtained by using the proper Laplace transform for the fractional-order derivatives. Using the results of this paper, the initialization response of any linear, commensurate-order, fractional-order system, with arbitrarily-long constant displacements in negative time can be determined.

Topics: Functions
Commentary by Dr. Valentin Fuster
2011;():353-360. doi:10.1115/DETC2011-48045.

A general formulation and solution of fractional optimal control problems (FOCPs) in terms of Caputo fractional derivatives (CFDs) of arbitrary order have been considered in this paper. The performance index (PI) of a FOCP is considered as a function of both the state and control. The dynamic constraint is expressed by a fractional differential equation (FDE) of arbitrary order. A general pseudo-state-space representation of the FDE is presented and based on that, FOCP has been developed. A numerical technique based on Grünwald-Letnikov (G-L) approximation of the FDs is used for solving the resulting equations. Numerical example is presented to show the effectiveness of the formulation and solution scheme.

Topics: Optimal control
Commentary by Dr. Valentin Fuster
2011;():361-367. doi:10.1115/DETC2011-48063.

In this paper, the distributed-order capacitor is discussed in both theoretical and physical ways. The distributed-order element networks are constructed by using the distributed-order capacitors and other electric elements. The impulse responses and the asymptotic properties of two typical distributed-order element networks are derived by using the complex path integral, in which all the results are verified by the NILT method. Based on the derived analytical impulse responses, we present a technique to perform the discretization of the above distributed-order element networks. A number of illustrated figures are presented to validate the concepts.

Topics: Networks
Commentary by Dr. Valentin Fuster
2011;():369-376. doi:10.1115/DETC2011-48079.

Anomalous transport of contaminants in groundwater or porous soil is a research focus in hydrology and soil science for decades. Because fractional diffusion equations can well characterize early breakthrough and heavy tail decay features of contaminant transport process, they have been considered as promising tools to simulate anomalous transport processes in complex media. However, the efficient and accurate computation of fractional diffusion equations is a main task in their applications. In this paper, we introduce a novel numerical method which captures the critical Mittag-Leffler decay feature of subdiffusion in time direction, to solve a class of time fractional diffusion equations. A key advantage of the new method is that it overcomes the critical problem in the application of time fractional differential equations: long-time range computation. To illustrate its efficiency and simplicity, three typical academic examples are presented. Numerical results show a good agreement with the exact solutions.

Commentary by Dr. Valentin Fuster
2011;():377-383. doi:10.1115/DETC2011-48151.

The present work concerns the multi-group consensus behavior of directed complex networks. The network consists of agents with heterogeneous fractional-order non-linear dynamics. It can be divided into several groups due to their dynamics or equilibriums. Each group will be stabilized at an equilibrium and different groups may have different steady state values. A necessary and sufficient condition is provided for the proposed pinning control law to be locally Mittag-Leffler stable. The conclusion turns to guarantee the exponential stable for integer-order systems. The collection of heterogeneous equilibriums is determined by the geometric multiplicity of the zero eigenvalue respect to the graph Laplacian. Simulations on fractional-order chaotic systems demonstrated the conclusions.

Commentary by Dr. Valentin Fuster
2011;():385-393. doi:10.1115/DETC2011-48175.

SCKAFO, stance-control knee-ankle-foot orthosis, is a type of orthosis that permits free knee motion during swing while resisting knee flexion during stance, supporting thereby the limb during weight bearing. This orthosis specially assists patients who have incomplete spinal cord injury and allows them to walk with the aid of canes or crutches, maintaining a proper gait. In this paper, based on the human walking biomechanics, the SCKAFO hybrid modeling is proposed, which consists of eight different stages whose evolution is given by means of four planar sensors on each foot. In the model, it is considered that the patients can move their hip but not their knee that will be controlled using a DC motor. Two fractional order controllers are designed, following decision based control techniques, to control the knee angle. Simulation results are given in order to demonstrate the efficiency of the system performance.

Topics: Modeling , Orthotics
Commentary by Dr. Valentin Fuster
2011;():395-401. doi:10.1115/DETC2011-48426.

This paper demonstrates the use of the Hankel operator to characterize the initial-condition response of a fractional-order system. A general initial-condition response can be determined for any input applied before t = 0 . Two techniques for approximating the Hankel operator are discussed. These approximation methods are applied to illustrative examples, demonstrating a general characterization of natural responses.

Topics: Approximation
Commentary by Dr. Valentin Fuster
2011;():403-408. doi:10.1115/DETC2011-48861.

In this paper, a class of fractional order systems is considered and simple fractional order observers have been proposed to estimate the system’s state variables. By introducing a fractional calculus into the observer design, the developed fractional order observers guarantee the estimated states reach the original system states. Using the fractional order Lyapunov approach, the stability (zero convergence) of the error system is investigated. Finally, the simulation results demonstrate validity and effectiveness of the proposed scheme.

Commentary by Dr. Valentin Fuster
2011;():409-418. doi:10.1115/DETC2011-48950.

Generalizing the classical Riemann-Liouville and Erdéyi-Kober fractional integral operators two integral transforms involving Gaussian hypergeometric functions in the kernel are considered. Formulas for composition of such integrals with generalized Bessel function of the first kind are obtained. Special cases involving trigonometric functions such as sine, cosine, hyperbolic sine and hyperbolic cosine are deduced. These results are established in terms of generalized Wright function and generalized hypergeometric functions.

Commentary by Dr. Valentin Fuster
2011;():419-426. doi:10.1115/DETC2011-47354.

The purpose of this investigation is to suggest and examine a trajectory follower control system for linear discrete dynamic model of omni-directional mobile robots to reach a controller with optimal inputs for drivers. Introducing optimal controllers for multi input-multi output control systems in acceleration and deceleration maneuvers to track a specified path is one of essential subjects for motion study of omni-directional mobile robots. Regulated drivers’ rotational velocities and torques greatly affect the ability of these robots to perform trajectory planner tasks. Moreover, environmental influencing factors shall also be considered in such robot models for accurate path planning. Presented tracking control system in this article provides an optimal solution to minimize differences between reference trajectory and system output in the lately developed simulated model. Trajectory following system together with implemented kinematic and dynamic modeling for an optimal controller to satisfy the path planning prerequisites is mainly discussed in this paper in several sections. Main topics presented and discussed in this article are considerable improvements in simulation of the newly optimized controller by Linear Quadratic Regulator and Tracking. Utilizing the new approach on tracking controller design results in the more precise and appropriate tracking behavior of omni-directional mobile robots as the simulation and experimental results confirm this issue.

Commentary by Dr. Valentin Fuster
2011;():427-435. doi:10.1115/DETC2011-47753.

The key to autonomous mobile-robot navigation is effective path planning and accurate self-localisation. The lack of self-localisation or inaccurate self-localisation makes any nonholonomic autonomous mobile robot blind in a navigation environment and will deter the robot’s ability to complete path following. In the last several years, many different systems have been considered for self-localisation, from using visual odometry to using a satellite triangulation method, better known as a global position system or GPS. All of these have benefits and detriments, the solution proposed here endeavors to offer more benefits than detriments, utilizing a novel method for self-localisation, employing a dual bearing finder digital compass configuration to resolve the relative location of an autonomous nonholonomic wheeled mobile robot. To facilitate the novel hybrid method, the utilization of the mobile robot’s multiple sensors, dual wheel quadrature shaft encoders and the digital compasses are required. To support the hardware requirements of the novel localisation methodology, the cutting edge technology of a 200 MHz 32-bit ARM 9 processor on a GHI ChipworkX module are employed. The software architecture is based on the Microsoft .NET Micro Framework 4.1 using C# and the Windows Presentation Foundation (WPF). Without the inputs from the dual compass configuration it would not be possible to solve the relative position of the mobile robot analytical. Without the dual compass configuration only a numeric solution is possible, which decelerates the localisation process. The mobile robot’s digital compasses are marked with unnatural markers, for faster identification by an overhead camera. Using the overhead camera tracking results and comparing the telemetry collected by the mobile robot, using the analytical equations, the validation of this method is proven. The most fundamental part of implementing a successful maneuverable nonholonomic mobile robot is accurate self-localisation telemetry. The biggest concern about using a self-localisation technique is the amount of computation it will require to complete the task. Ideally, having an analytical solution to position offers the benefit of a single solution, where the numeric solution has many solutions and requires more time and computation to derive the solution. The benefit of the dual compass configuration is that it offers an analytical solution to the hybrid model that utilizes quadrature shaft encoders and digital compasses. This methodology evidently presents a novel approach where visual odometry is not possible.

Topics: Mobile robots
Commentary by Dr. Valentin Fuster
2011;():437-440. doi:10.1115/DETC2011-48190.

A compact or portable mechatronic embedded system application has a strictly demands of volume and/or power consuming. Comparing with electronic parts, switches and/or actuators take the most proportion of volume or weight and power consuming of the whole system. A novel method of connecting multiple switches/actuators built by using electro-rheological fluid and a pair of governing electrodes and their control strategy are introduced in this paper. By using this method, the numbers of control components are changed from N times M to N plus M, the volume and weight reduced largely. A series structure is used in the application on multi-line Braille electro-book for blind people as a demonstration of this novel method. It provides a novel solution of shrinking system for a compact or portable mechatronic embedded system application.

Commentary by Dr. Valentin Fuster
2011;():441-449. doi:10.1115/DETC2011-48429.

This paper describes an integrated optimization process of dynamic systems including design parameters and control algorithms. In contrast to known approaches the developed approach is based on an optimization loop including the evaluation of the dynamical behavior of technical systems with respect to the behavior and related properties in time and frequency domain. This includes as well the behavior of the system, the objective function as the formulation of the restrictions to be considered for the dynamical behavior (stationary and instationary). The proposed approach is declared in detail and will be illustrated using two typical technical applications as examples. The first application example is the optimization of the control system of an active magnetic bearing (AMB) rotor system. Hereby the modeling of the AMB rotor system is briefly introduced. An H∞ controller is designed for the control of the system. The performance both in time and frequency domain is optimized in parallel. The algorithm will be explained by simulation examples. The second example is the optimization of the pow-ermanagement system of a fuel cell/supercap-based hybrid electric powertrain. Hereby the modeling of the electric power flow within the powertrain system is demonstrated and its influence on certain system properties like availability, efficiency, and typical aging mechanisms is discussed. The proposed method leads to near-optimal results in a few steps for both of the systems introduced.

Commentary by Dr. Valentin Fuster
2011;():451-456. doi:10.1115/DETC2011-47873.

Three-dimensional sensing is a vital field in mobile robotic applications. This work proposes an application of a Time-of-Flight 3D Photonic Mixer Device (PMD) camera for the navigation of an Omni-directional mobile robot. The 3D PMD camera enables real time distance detection as well as the capturing of grayscale images. In our framework, the application of the 3D PMD camera is aimed at solving the problem of environmental perception in mobile robotics. In this paper, we present the development of a MATLAB-based kit for the control of an Omni-directional mobile robot supported by a data acquisition board. The communication interface of the camera, used to close the system’s control loop, has been also developed. We further present results of different experiments including online obstacle detection and avoidance. In addition, an adaptive pose determination for the robot is proposed.

Commentary by Dr. Valentin Fuster
2011;():457-463. doi:10.1115/DETC2011-48085.

Piezoelectric stack actuators are commonly used in a number of different position control applications due to their compactness, high resolution, speed and dynamic properties. For accurate position control, position feedback has traditionally been employed since the parameters of the constitutive equations change with temperature and age. In addition, the identification of constitutive parameters is complicated by the presence of hysteresis voltage that is not accounted for in the linear constitutive equations. Recently, there has been a push towards sensor less control. This approach requires an accurate identification technique of the constitutive parameters. For this purpose, the constitutive equations used to identify the piezoelectric parameters are usually considered linear under a low electric field. However, at larger driving voltages hysteresis effect become significant and the parameters identified at lower excitation levels are no longer valid. This is traditionally addressed by providing constitutive parameters as a function of applied voltage. However, this is usually done for the ascending hysteresis branch only. The changes due to the descending hysteresis branch are commonly ignored. As a result, it is often difficult to match the constitutive equations to experimental data. We propose a new identification procedure that is based on online capacitance measurements of the piezo actuators. These measurements indicate, that the piezo capacitance is not constant, but a linear function of linearized piezo voltage. Using this result, we are able to construct values for the remaining constitutive parameters that are largely independent of piezo voltage. The resulting constitutive equations match our experimental actuator performance well no matter where they are applied in the hysteresis loop. This new identification technique then provides more accurate piezo models that are very useful for developing sensor less control strategies for piezo actuators.

Commentary by Dr. Valentin Fuster
2011;():465-469. doi:10.1115/DETC2011-48161.

Fourier transform spectrometers require an interferometric optical setup, where a precisely controlled motion of a mirror on a moving stage and a reference mirror are required. FR4, a common printed circuit board substrate, and the standard PCB technology is used to develop a simple gimbaled scanner structure with high precision to implement into a low-cost and viable Fourier Transform Spectrometer. On top of the corner cube reflector based tilt-insensitive setup, magnetic actuation optimization using twin opposing magnets solution is found to be helpful to enhance interference data. Large Lorentz force is generated for out-of-plane deflection while the torsional motion of the scanner is restricted. ±162.8um out-of-plane translation at 149 Hz resonance is realized with torsion effect deteriorated result which corresponds to <1nm spectral resolution at visible wavelengths.

Commentary by Dr. Valentin Fuster
2011;():471-479. doi:10.1115/DETC2011-48305.

This paper presents a practical approach of FEA modeling and optimization of the design of the compact electromagnetic actuator. This special actuator is designed to perform the gear shifts in the synchronized segmentally interchanging pulley transmission system (SSIPTS.) The geometry and material properties of the actuator, which are confined by the assembling space and running condition of SSIPTS, are parametrically optimized by using FEA package, Comsol Multiphysics. The current density of coil, the geometric parameters of magnet, and the permeability of structural materials are major control variables in the optimization of the novel actuator. The target of the optimization process is to find the maximum electromagnetic force and the minimum mass of the entire device within the available space in the transmission package. The simulation results for the optimized design are presented and further compared with the performance requirements of the actuator.

Commentary by Dr. Valentin Fuster
2011;():481-489. doi:10.1115/DETC2011-48411.

In most cases the deleterious effects associated with the occurrence of leak may present serious problems and therefore leaks must be quickly detected, located and repaired. The problem of leakage becomes even more serious when it is concerned with the vital supply of fresh water to the community. In addition to waste of resources, contaminants may infiltrate into the water supply. The possibility of environmental health disasters due to delay in detection of water pipeline leaks has spurred research into the development of methods for pipeline leak and contamination detection. Leaks in water pipes create acoustic emissions, which can be sensed to identify and localize leaks. Leak noise correlators and listening devices have been reported in the literature as successful approaches to leak detection but they have practical limitations in terms of cost, sensitivity, reliability and scalability. To overcome those limitations the development of an in-pipe traveling leak detection system is proposed. The development of such a system requires a clear understanding of acoustic signals generated from leaks and the study of the variation of those signals with different pipe loading conditions, leak sizes and surrounding media. This paper discusses those signals and evaluates the merits of an in-pipe-floating sensor.

Topics: Sensors , Pipes , Leakage
Commentary by Dr. Valentin Fuster
2011;():491-497. doi:10.1115/DETC2011-48602.

This paper presents a design for an electric motor that can potentially be produced by a personal 3D printer. The concept of a Cyclic Fabrication System — a network of tools, machines, and processes capable of producing all of its constituent components — is discussed in order to provide context for the various factors influencing the design. The motor is an axial-airgap permanent-magnet motor with a flat 2-layer coil. The coil pattern makes minimal use of crossovers or vias, and is well-suited to several methods for fabricating conductive structures that are currently under development. A versatile MATLAB script is presented which is used to generate the coil pattern. Coil geometry is controlled parametrically, and it is straightforward to generate a wide variety of coils, corresponding to different arrangements of magnets and desired coil spacings. The motor uses plastic roller bearings that are easily fabricated.

Commentary by Dr. Valentin Fuster
2011;():499-505. doi:10.1115/DETC2011-48732.

An embedded sensor network is a network of sensor nodes deployed in the physical world that interacts with the environment. Each sensor node is a physically small and relatively inexpensive computer that has one or more sensors. These sensor nodes are often networked, allowing them to communicate and cooperate with each other to monitor the environment. Typically, an embedded sensor network is controlled by its own applications that can access the sensor nodes within the network. On the other hand, the sensor nodes cannot be easily accessed by applications outside of the network. Moreover, even within the same network, different applications might encounter a race condition when they are trying to access a sensor node simultaneously. The issue is related to system management. However, not much research has been done with a focus on the management of sensor nodes. In the past few years, Cloud computing has emerged as a new computing paradigm to provide reliable resources, software, and data on demand. As for resources, essentially, Cloud computing services provide users with virtual servers. Users can utilize virtual servers without concerning about their locations and specifications. With such an inspiration, this paper proposes a system, Sensor Agent Cloud, where users can access the sensor nodes without worrying about their locations and detailed specifications. Sensor Agent Cloud virtualizes a physical sensor node as a virtual “sensor agent”. Users can use and control sensor agents with standard functions. Each sensor agent operates on behalf of its user. The mandatory coordination of these sensor agents is related to the system management. Therefore, Sensor Agent Cloud must be an autonomic system that manages itself with minimum human interference. In addition, Sensor Agent Cloud supports international standard technologies regarding programming and agent communication (C and IEEE FIPA standard). Thus, it is expected that the proposed Sensor Agent Cloud can enhance the applicability and usability of embedded sensor networks in many application areas.

Topics: Sensors
Commentary by Dr. Valentin Fuster
2011;():507-510. doi:10.1115/DETC2011-48893.

A tactile sensor for slip detection is necessary for humanlike grasping in robot hand. This paper reports a capacitive tactile slip sensor that can detect slip on the surface of the sensor structure. The newly developed capacitive slip sensor uses acrlyro-nitrile butadien rubber (NBR) as substrate. The presented sensor device in this paper has fingerprint -like structures that are similar with the role of the human’s fingerprint. Movement of the structure that attached on surface of substrate arise capacitance changes, and these are used to detect slip. We carried out slip experiment by prototype of capacitive slip sensor and slip was successfully detected.

Topics: Sensors
Commentary by Dr. Valentin Fuster
2011;():511-516. doi:10.1115/DETC2011-48970.

Reformer tubes are commonly used in process industry. They are high cost components. The service life of reformer tubes is primarily determined by creep damage. To successfully manage the reformer tubes requires balancing creep life against the production gains of higher temperatures. The key to this requires an ongoing knowledge of the condition of the tubes. Monitoring the diametrical change of the tubes caused by creep damage is one of the most popular methods used in industry. However, the available reformer tube diametrical checking systems are very expensive. This paper presents a novel mechanical sensing unit for reformer tube diametrical measuring. The system is low cost and meets the industrial company specified requirements. Test and field trials made on the prototype gave a very encouraging result. With further study, it is expected that a robust and cost effective reformer tube diametric measuring system can be developed.

Commentary by Dr. Valentin Fuster
2011;():517-523. doi:10.1115/DETC2011-48976.

Reformer tubes are high cost components in process industries. The service life of the reformer tubes is primarily ended by creep damage, which is caused by operation at high pressure and temperature. As a result of the creep damage, the geometry of reformer tubes changes especially the diameter. Therefore, monitoring the diametric changes of the reformer tubes is able to help to judge the degree of creep —damage. Different sensors, methodologies and techniques are proposed to obtain and monitor the diametric data of the reformer tubes. However, the cost of the dominant systems available is hard for majority of the industrial companies to afford. This paper presents a novel design of a microcontroller-based, wireless data acquisition system for obtaining reformer tube internal diameter data. The system focused on using cost effective components and methodologies. Tests made on the prototype showed that the system is able to reliably transmit reformer tube internal diametric data to a computer located on top of the reformer tube in real time.

Commentary by Dr. Valentin Fuster
2011;():525-533. doi:10.1115/DETC2011-48111.

The design of mechatronic systems involves different technical and scientific disciplines and it is often difficult to arbitrate between engineers’ points of view so as to satisfy consumers’ needs. In order to converge to satisfactory tradeoffs, designers have to collaborate although they often can understand neither other designers’ issues nor their solving methods. Thus there is no guarantee each designer has spent the needed effort to reach some global optimum. Moreover, the number of design parameters is generally high and it may be difficult to grasp their influence on the design criteria that even can be contradictory. The purpose of this research is to propose methods and tools in order to help designers to evaluate candidate solutions. At this aim, an original heuristic based approach is proposed to compute non-dominated solution sets i.e. Pareto fronts. The analysis of the candidate solutions is facilitated using Self Organization Maps which provide designers with easy readable two dimensional cards. Our approach is fully illustrated in the case of the design of a 2-Degrees Of Freedom robot.

Topics: Design , Mechatronics
Commentary by Dr. Valentin Fuster
2011;():535-544. doi:10.1115/DETC2011-48880.

This paper presents a tactile synthesis method to provide roughness and texture coarseness sensations using a selective stimulation approach implemented by a tactile display. Digitizing, elaborating and processing real material surfaces obtain signals. The selection of their frequency range is based on the reactive frequencies of SAI and FAI types receptors. An electro-tactile display provided with a mechanical vibration to stimulate FAII units located at the deeper skin layers has been developed. A SW tool allows to manage selective signals modulation and configuration according to the displayed material. The research aims at overcoming a crucial problem concerning the signals adopted by most electro-tactile displays to stimulate skin mechanoreceptors. The paper focuses on the description of the adopted method and of the implemented software tool to control the tactile display. Preliminary experimentations were carried out to measure the system’s latency, accuracy and reliability. Experimental sessions show a promising system response: minimal latency (30ms), good reliability (>98%) and acceptable accuracy (>70%).

Commentary by Dr. Valentin Fuster
2011;():545-553. doi:10.1115/DETC2011-48941.

This paper describes the servo actuated transmission system required to drive a desktop haptic strip interface. The haptic strip is a mechatronic device which is used for exploration of virtual surfaces with aesthetic value. The simulation of tasks, such as the exploration of aesthetic real surfaces made by industrial designers in order to check the quality of prototypes, require full hand contact with the shape on a one-to-one scaled representation of the object. Our mechatronic device allows a continuous, free hand contact on a developable real plastic tape actuated by a servo-controlled mechanism in which is used the tessellation approach. In fact, the triangular mesh simplifies the conformation of the developable real surface as the virtual one. This paper discusses the design concept, novel kinematics and mechanics, improvements of the transmission system and control for the Desktop Strip.

Topics: Haptics , Strips
Commentary by Dr. Valentin Fuster
2011;():555-563. doi:10.1115/DETC2011-48995.

In the next future Virtual Reality technologies will allow the dramatic reduction of the development time of “soft products”, like textiles, household papers and car interiors, making possible the subjective assessment of their fine mechanical properties, through the realistic rendering of the visual and haptic sensations arising during the physical interaction of these objects with the human hand. This paper deals with the development issues of a complete haptic interface, able to allow the simultaneous generation on the human hand of both kinesthetic and tactile stimulations. The device has been conceived for the haptic rendering of textiles and is composed by a multipoint force feedback device, in charge of generating arbitrary resultant forces on the index and thumb fingertips, and by two independent tactile arrays, in charge of generating time and spatially distributed tactile stimulations on the palmar surface of the two fingertips. After a brief discussion of the reference configuration selected for the whole haptic interface, it has been reported the functionalities, architecture and performances of the realized force feedback device, hosting the tactile arrays. Then the papers focuses on the development issues of a suitable tactile array, discussing its general requirements and the selected architecture. Finally the technical solutions selected for the implementation of its main components and their experimental evaluations are reported.

Commentary by Dr. Valentin Fuster
2011;():565-574. doi:10.1115/DETC2011-47185.

We are developing a framework (RISCWare) for the modular design and integration of sensory modules, actuation platforms, and task descriptions that will be implemented as a tool to reduce efforts in designing and utilizing robotic platforms. The framework is used to customize robotic platforms by simply defining the available sensing devices, actuation platforms, and required tasks. The main purpose for designing this framework is to reduce the time and complexity of the development of robotic software and maintenance costs, and to improve code and component reusability. Usage of the proposed framework prevents the need to redesign or rewrite algorithms or applications due to changes in the robot’s platform, operating systems, or the introduction of new functionalities. In this paper, the RISCWare framework is developed and described. RISCWare is a robotic middleware used for the integration of heterogeneous robotic components. RISCWare consists of three modules. The first module is the sensory module, which represents sensors that collect information about the remote or local environment. The platform module defines the robotic platforms and actuation methods. The last module is the task-description module, which defines the tasks and applications that the platforms will perform such as teleoperation, navigation, obstacle avoidance, manipulation, 3-D reconstruction, and map building. The plug-and-play approach is one of the key features of RISCWare, which allows auto-detection and auto-reconfiguration of the attached standardized components (hardware and software) according to current system configurations. These components can be dynamically available or unavailable. Dynamic reconfiguration provides the facility to modify a system during its execution and can be used to apply patches and updates, to implement adaptive systems, or to support third-party modules. This automatic detection and reconfiguration of devices and driver software makes it easier and more efficient for end users to add and use new devices and software applications. In addition, the software components should be written in a flexible way to get better usage of the hardware resource and also they should be easy to install/uninstall. Several experiments, performed on the RISCbot II mobile manipulation platform, are described and implemented to evaluate the RISCWare framework with respect to applicability and resource utilization.

Topics: Robotics
Commentary by Dr. Valentin Fuster
2011;():575-582. doi:10.1115/DETC2011-47194.

Mobile robots for inspection and surveillance of hard-to-reach and hazardous areas e.g. resulting from a building collapse in the course of a natural or man-made catastrophe have to possess enhanced rough terrain mobility capabilities. First, they must be able to navigate through a given environment and to avoid insurmountable obstacles. Second, they must have the ability to traverse different forms of ground without getting immobilized by a loss of traction. Third, they must be able to negotiate a wide spectrum of obstacles including e.g. wide gaps and high steps. These abilities can be described as a mobile robots performance indices “maneuverability”, “trafficability” and “terrainability”. As a consequence, mobile robot concepts for disaster control and search-and-rescue tasks always have to be developed and evaluated with regard to these performance indices. In principle, considerable potentials with regard to mobility in unstructured and rough environments offer kinematically redundant locomotion systems equipped with powered wheels or tracks which are inspired by their biological archetype snake. These potentials are based on the systems’ snake-like; modular design as well as their given kinematic redundancy. Due to their slender, modular and flexible design the systems are basically able to travel and maneuver through noticeable narrow passes and tunnels. Further on, their kinematic redundancy can be used for a purposeful posture and terrain adaptation to safeguard traction and the system’s trafficability, respectively. Finally, the systems’ modular and articulated design, both, can be used to achieve an outstanding terrainability and to be able to negotiate remarkable obstacles. The described and expected potentials of kinematically redundant locomotion systems have to be investigated in detail as well as evaluated in practice. To be able to do so, a demonstrator has been developed and implemented for intense mobility-oriented research and experimentation. The mobile robot and first experimental results are described in the paper at hand. The system stands out especially due to an innovative sensory for slip and contact force detection.

Commentary by Dr. Valentin Fuster
2011;():583-588. doi:10.1115/DETC2011-47198.

Self-reconfigurable modular robot consists of many identical modules. By changing the connections among modules, the structure of the robot can flexibly change into many other structures. First, the module is designed which can finish the self-repairing action and its disconnection/connection mechanism is analyzed. Second, a distributed self-repairing process based on the geometrical characters of the modular robot is presented. The method of the Breadth-First-Search and the Depth-First-Search is applied to look for a locomotion path by which a faulty module is ejected and replaced by a spare module. The method can be used to show the self-repairing task of most lattice-type modular robots. It’s effective to solve large numbers of computing problems when the faulty module is inside a large-scale system. At last, a simulation of (2 × 4 + 1)3 modules shows the feasibility and effectiveness of the self-repairing method in the self-reconfigurable robot.

Topics: Maintenance , Robots
Commentary by Dr. Valentin Fuster
2011;():589-598. doi:10.1115/DETC2011-47201.

This paper deals with the position regulation problem of a redundant planar parallel robot for the case in which only the joint position measurements are available, and presents an image based visual servoing scheme to solve this problem. It uses Proportional Integral and Derivative algorithm to compute the torques for the robot active joints together a linear filter to obtain velocity estimates from visual position measurements and shows that the robot end-effector converges to the desired position. Lyapunov Stability Theory allows concluding closed loop stability without invoking the LaSalle-Krassovsky invariance principle. Experimental results are presented for a laboratory prototype and allow evaluating the performance of the closed loop system.

Topics: Robots
Commentary by Dr. Valentin Fuster
2011;():599-605. doi:10.1115/DETC2011-47468.

This paper presents the progress of work toward state of art design and development of active suspension low level impedance control for high speed (> 80km/h) multi-terrain vehicles. We have used a quarter car suspension model for mechanical system modeling. The system utilizes hydraulic actuation to change the impedance at joints. The control strategy is designed such that the excitation force or disturbance from the environment is balanced such that the system follows ideal impedance parameters. Control synthesis is performed on the position control scheme for the analysis of sensitivity, robustness and performance. In the end different control tuning techniques are used to improve the impedance control performance under environmental conditions.

Commentary by Dr. Valentin Fuster
2011;():607-613. doi:10.1115/DETC2011-47711.

Normally, one link of the four-bar linkage is fixed to the frame; another supplies the input; the motion of the third one with respect to the base is the output. A novel application of the four-bar linkage is proposed that a parallelogram mechanism is applied to be a rolling robot for which there is neither a constant base nor a constant output. Four sides take turns to be the support link and an adjacent link of the support one is regarded as the output in turn. The rolling motion is actuated by an internal angle change which is supplied by the rocker oscillation of a crank-rocker mechanism, not a motor directly. The unidirectional rotation of the motor simplifies the control system. A planar 4R parallelogram is suggested to roll straight under the driving of a planar 4R crank-rocker mechanism. For turning, a spatial RSRS quadrilateral is presented to roll and turn driven by a spatial RSUS crank-rocker mechanism. The principle of tipping and rolling are explained. Simulations testify the parameter design of the driving rank-rocker mechanism. An experimental prototype is fabricated to verify the feasibility of the concept.

Topics: Mechanisms
Commentary by Dr. Valentin Fuster
2011;():615-622. doi:10.1115/DETC2011-47735.

This paper investigates simultaneous localization and mapping (SLAM) problem by exploiting the Microsoft Kinect™ sensor array and an autonomous mobile robot capable of self-localization. The combination of them covers the major features of SLAM including mapping, sensing, locating, and modeling. The Kinect™ sensor array provides a dual camera output of RGB, using a CMOS camera, and RGB-D, using a depth camera. The sensors will be mounted on the KCLBOT, an autonomous nonholonomic two wheel maneuverable mobile robot. The mobile robot platform has the ability to self-localize and preform navigation maneuvers to traverse to set target points using intelligent processes. The target point for this operation is a fixed coordinate position, which will be the goal for the mobile robot to reach, taking into consideration the obstacles in the environment which will be represented in a 3D spatial model. Extracting the images from the sensor after a calibration routine, a 3D reconstruction of the traversable environment is produced for the mobile robot to navigate. Using the constructed 3D model the autonomous mobile robot follows a polynomial-based nonholonomic trajectory with obstacle avoidance. The experimental results demonstrate the cost effectiveness of this off the shelf sensor array. The results show the effectiveness to produce a 3D reconstruction of an environment and the feasibility of using the Microsoft Kinect™ sensor for mapping, sensing, locating, and modeling, that enables the implementation of SLAM on this type of platform.

Commentary by Dr. Valentin Fuster
2011;():623-630. doi:10.1115/DETC2011-47747.

Tele-operation of mobile-manipulator systems (MMS) is typically done by modeling both the manipulator and mobile base as a single system combined with the use of various redundancy resolution techniques to achieve coordinated motion. In this work, the Omnibot MMS is controlled by a 3-DOF (degrees-of-freedom) haptic joystick. The base is a holonomic platform having 3-DOF supporting a 3-DOF manipulator capable of position control within its workspace. By controlling the base and manipulator individually, redundancy resolution techniques are not required because the master has equal DOF to the device it is controlling at any given time. Two command strategies are proposed herein for automatic switching of control between the manipulator and base. The first command strategy is a virtual wall method that uses haptic forces to make the operator feel like they are pushing against a wall at the edge of the manipulator’s workspace, resulting in the base moving. The second command strategy is a two state approach in which each state controls a different device and switching between the two is done by breaking through the workspace limits. With the help of haptic forces, the operator has the sensation of breaking through a compliant surface when switching states. The two proposed strategies were implemented and tested on the Omnibot MMS and both subjective and objective data was used to evaluate and compare the two methods.

Topics: Haptics , Manipulators
Commentary by Dr. Valentin Fuster
2011;():631-636. doi:10.1115/DETC2011-47816.

The paper faces the problem of improving the flexibility of the manufacturing plant by rising the level of reconfigurability and the intelligence of peri-robotics. In particular the results obtained within the SwarmItFIX research project are presented. They refer to the concept and realization of robotic swarm fixturing for the support of airplane and automotive body panels during their manufacturing.

Commentary by Dr. Valentin Fuster
2011;():637-645. doi:10.1115/DETC2011-47991.

This paper presents a distributed second-order control algorithm for deploying a group of nonholonomic mobile robots into an unknown environment to establish and maintain desired sensor coverage. The general control framework is formulated based on Hamilton’s principle. The control input is defined in the form of a potential/force field. A multi-robot collision avoidance scheme is also presented. The effectiveness of the proposed deployment control scheme is verified through both simulations and experiments. Main performance factors, including equilibrium deployment configuration, convergence of inter-robot coverage distance and collision avoidance, are presented and analyzed.

Commentary by Dr. Valentin Fuster
2011;():647-655. doi:10.1115/DETC2011-48203.

This paper presents the learning experience gained while designing and implementing a vision based autonomous tracked sorting robot in a mechatronics design class for its application in color based sorting, mapping and exploration missions. The different steps taken in order to reach the final system are presented. This paper focuses on the kinematic modeling of the tracked vehicle and the gripper, and discusses in details the selection process of the reboot’s components. The system was tested and results are shown using snap shots of the final demo.

Topics: Robots
Commentary by Dr. Valentin Fuster
2011;():657-664. doi:10.1115/DETC2011-48635.

In this study, we propose an intelligent automated disassembly cell for online (real time) selective disassembly. The cell is composed of an industrial robotic manipulator, a camera, range-sensing and component segmentation visual algorithms. The cell prototype allows for robotic sensory-driven disassembly under uncertainty. An online genetic algorithm model for selective disassembly is also proposed for optimal and near/optimal disassembly sequencing.

Commentary by Dr. Valentin Fuster
2011;():665-669. doi:10.1115/DETC2011-48857.

Spherical mobile robots belong to a class of mobile robots which may have applications ranging from exploration to entertainment. This paper presents our preliminary kinematic study of spherical mobile robots which are driven by an omni-wheel based internal driving unit (IDU). At first, we discuss the conceptual design of spherical mobile robots with an omni-wheel based IDU. Several IDUs are proposed. Then we derive the velocity equation of a spherical mobile robot with an omni-wheel based IDU. Finally, two isotropic configurations of spherical mobile robots with an omni-wheel based IDU are identified. This work lays the foundation for the further investigation on spherical mobile robots with an omni-wheel based IDU.

Commentary by Dr. Valentin Fuster
2011;():671-676. doi:10.1115/DETC2011-47679.

This paper is to present a novel design of the Iterative Learning Observer (ILO) for the purpose of fault estimation. With the new design of ILO, initial oscillation of the fault estimate is dramatically reduced. The learning accuracy is accordingly improved. Convergence of the ILO to the system is proved and simulation study is conducted. It shows that accurate fault estimation can be performed by the new ILO.

Topics: Design
Commentary by Dr. Valentin Fuster
2011;():677-680. doi:10.1115/DETC2011-47680.

This paper is to develop a general form for Total Measurable Fault Information-based Residual (ToMFIR) approach to fault detection in dynamic systems. The ToMFIR is initially established for systems with a constant control input signal and a fault approaching to a constant. Practical systems satisfying the aforementioned conditions is few. That is why a generalized form is developed in this work. The definition of the ToMFIR is first introduced and the special case is also presented for the continuity of the statement. Based on a stable and linear time-invariant system, the general form of the ToMFIR is derived, and a practical DC motor example, with a PID controller, is used to demonstrate the effectiveness and robustness of the ToMFIR-based fault detection.

Commentary by Dr. Valentin Fuster
2011;():681-689. doi:10.1115/DETC2011-48174.

Determining the residual life time of systems is a determinant factor for machinery and environment safety. In this paper the problem of estimate the residual useful life (RUL) of turbo-fan engines is addressed. The adopted approach is especially suitable for situations in which a large amount of data is available offline, by allowing the processing of such data for the determination of RUL. The procedure allows to calculate the RUL through the following steps: features extraction by Artificial Neural Networks (ANN) and determination of remaining life time by-prediction models based on a Hidden Markov Model (HMM). Simulations confirm the effectiveness of the proposed approach and the promising power of Bayesian methods.

Topics: Engines , Turbofans
Commentary by Dr. Valentin Fuster
2011;():691-697. doi:10.1115/DETC2011-48493.

Machine faults and breakdowns are a concern for the manufacturing industry. Automated assembly machines typically employ many different types of sensors to monitor machine health and feedback faults to a central controller for review by a technician or engineer. This paper describes progress with a project whose goal is to examine the effectiveness of using machine vision to detect ‘visually cued’ faults in automated assembly equipment. Tests were conducted on a laboratory scale conveyor apparatus that assembles a simple 3-part component. The machine vision system consisted of several conventional webcams and image processing in LabVIEW. Preliminary results demonstrated that the machine vision system could identify faults such as part jams and feeder jams; however the overall effectiveness was limited as this technique can only detect faults known prior to creating the vision system. Future work to create a more robust system is currently underway.

Commentary by Dr. Valentin Fuster
2011;():699-706. doi:10.1115/DETC2011-48553.

The CNC (Computer Numerical Control) machine tools are complex mechatronic systems applied to the manufacture with high precision and high speeds. To achieve high accuracy and operational efficiency, the disturbance and friction, which occur during machining process, should be reduced as low as possible. This paper develops an analysis of influence by cutting force and friction effect in the control of machine tool based on the CNC dynamic model and parameters identification. For this purpose, the study focuses on Coulomb and Viscous nonlinear friction and the external disturbances. The analysis uses control position error, contour error, and stability to determine the influence of friction and disturbance. The results show that Viscous friction has more critical influence on system than the Cutting force and Coulomb. The work contributes in recognizing which parameters have greater influence on the machine behavior through dynamic analysis with the identification strategy, in order to design and improve the control structure for a real CNC system.

Commentary by Dr. Valentin Fuster
2011;():707-716. doi:10.1115/DETC2011-47989.

This paper addresses the critical issue of establishing and maintaining desired wireless communication connectivity in a team of collaborative mobile robots, which is highly demanded for reliable functioning of multi-robot systems but challenging in realistic environments. The signal propagation of wireless communications among mobile robots is affected by not only the transmission power and distance but also obstacles and other environmental conditions as well as robot movement, which result in signal loss, attenuation, multi-path fading and shadowing. Consequently, the communication condition among mobile robots in a physical environment is usually unstable, and it is difficult to accurately predict the actual communication ranges of robots. We propose a decentralized control strategy which, based on perceived link quality, adopts fuzzy control to accommodate the fluctuating communication condition, and approach and maintain desired and reliable communication connections among neighboring robots. The effectiveness of the proposed scheme has been verified in several simulated environments with different signal propagation conditions based on a probabilistic signal propagation model.

Commentary by Dr. Valentin Fuster
2011;():717-726. doi:10.1115/DETC2011-48041.

This paper develops a tip-tilt motion controller of fast steering mirror (FSM) in the Giant Magellan telescope (GMT). A mathematical model of tip-tilt motion system of FSM is derived, and then based on this model, stability analysis is carried out. A heuristic adaptive controller is designed for the tip-tilt motion control with modeling error. The heuristic controller consists of two different adaptations such as initial adaptive control and adaptation at steady state errors . Through numerical simulations, the validity of the controller is illustrated. After that this paper addresses several practical issues like disturbance from wind, actuator saturation and resonance frequency from mechanical structure in implementing the controller to the actual system.

Commentary by Dr. Valentin Fuster
2011;():727-734. doi:10.1115/DETC2011-48042.

In this paper, we address the optimal ground antenna scheduling problem for multiple satellites when multiple satellites have visibility conflicts at a ground station. Visibility conflict occurs when multiple satellites have either overlapping visibilities at a ground station or difference with time of loss of signal (LOS) of a satellite and time of acquisition of signal (AOS) of another satellite is less than reconfiguration time of ground station. Each satellite has a priority value that is a weight function with various factors. Multi-antenna scheduling (MAS) algorithm 1 and Multi-antenna scheduling (MAS) algorithm 2 are proposed to find the optimal schedule of multi-antenna at a ground station using pre-assigned priority values of satellites. We use the depth first search (DFS) method to search the optimal schedule in MAS algorithm 1 and MAS algorithm 2. Through the simulations, we confirm the efficiency of these algorithms by comparing with greedy algorithm.

Commentary by Dr. Valentin Fuster
2011;():735-744. doi:10.1115/DETC2011-48699.

Mobile agent technology has become an important approach for the design and development of distributed systems. However, there is little research regarding the monitoring of computer resources and usage at large scale distributed computer centers. This paper presents a mobile agent-based system called the Mobile Agent Based Computer Monitoring System (MABCMS) that supports the dynamic sending and executing of control command, dynamic data exchange, and dynamic deployment of mobile code in C/C++. Based on the Mobile-C library, agents can call low level functions in binary dynamic or static libraries, and thus can monitor computer resources and usage conveniently and efficiently. Two experimental applications have been designed using the MABCMS. The experiments were conducted in a university computer center with hundreds of computer workstations and 15 server machines. The first experiment uses the MABCMS to detect improper usage of the computer workstations, such as playing computer games. The second experimental application uses the MABCMS to detect system resources such as available hard disk space. The experiments show that the mobile agent based monitoring system is an effective method for detecting and interacting with students playing computer games and a practical way to monitor computer resources in large scale distributed computer centers.

Topics: Data centers
Commentary by Dr. Valentin Fuster
2011;():745-752. doi:10.1115/DETC2011-48904.

Today Unmanned Aerial Vehicles (UAVs) and in particular quad-rotors represent novel platforms to accomplish a wide set of missions as surveillance, Search & Rescue, inspection, photogrammetry. The main limitation of these vehicles is represented by the restricted operating area. The area is mainly limited by power supplies (batteries or fuel). A strategy to overcame this limitation is to increase the number of vehicles forming a coalition. The main benefit of coalition formation are the extended mission range and the capability to increase the sensorial set. Each vehicles is a part of a dynamic network that must be properly coordinated in order to optimize all the available resources. In this paper a new framework for simulation of unmanned vehicles in cooperative scenarios is first presented. The framework is based on the interaction of a physics-engine, which simulates the dynamics of vehicles and their interaction with world increasing the realism of simulation, and a simulation environment where the high-level strategy is designed/developed. A Model Predictive Control (MPC) is then introduced to solve the problem of leader-follower applied to quad-rotors. Using the developed framework and the MPC technique is possible to easily instantiate the coalition minimizing also a cost function. The obtained results from the control strategy point of view show that positioning error at steady state is equal to zero. The MPC allows also the modelling of different conflicting constraints as the control actions, positioning error, and fuel/energy consumption.

Commentary by Dr. Valentin Fuster
2011;():753-764. doi:10.1115/DETC2011-47024.

Approximately 82 percent of all amputations performed in the United States are transtibial amputations, in which the leg is removed below the hiee. Because the knee joint is left intact the use of prosthetics is one of the most preferred methods for returning mobility to amputees. The improvement of prosthetics for transtibial amputees is currently an area of intense research. This paper summarizes the state of the art of prosthetics for transtibial amputees by focusing on the four major components associated with standard transtibial prosthetic. The socket transfers the forces between the residual limb and the prosthetic. A suspension system ensures that solid contact is maintained between the leg and the artificial limb. The prosthetic foot is attached to the socket by a pylon, which also accounts for length of limb lost during amputation. Prosthetic feet come in many forms ranging from little more than wooden blocks to carbon fiber sprinting feet. Two recent advances in transtibial prosthetics include the procedures of direct skeletal attachment, and distal tibiofibular bone bridging which increases the weight bearing capability of the residual limb.

Commentary by Dr. Valentin Fuster
2011;():765-769. doi:10.1115/DETC2011-47179.

Applying continuous passive rehabilitation movements as part of the recovery program of patients with post-traumatic disabilities of the bearing joints of the inferior limbs requires the development of new high performance equipment. The proposed equipment is designed to be deployed in rehabilitation medical care, its specific objectives being maintenance and recovery of body functions by means of kinetic and orthotic techniques. The paper presents a variant of rehabilitation equipment the novelty of which consists in the utilization of compliant (soft) fluidic actuators of linear type and variable stiffness. The proposed rehabilitation equipment benefits from a cost efficient, simple and robust construction, being easy to use by persons affected by dysfunctions of the bearing joints. The paper presents kinematic, geometrical and dynamic modeling of the proposed rehabilitation equipment, highlighting its advantages compared to equipment endowed with electric-mechanical linkages. Further, the paper presents the actuation diagram of the equipment. Conceived to be actuated by pneumatic muscles the equipment represents an absolute novelty.

Commentary by Dr. Valentin Fuster
2011;():771-777. doi:10.1115/DETC2011-47445.

Natural orifice transluminal endoscopic surgery (NOTES) is a novel surgical technique which uses endoscopic tools to perform mini invasive abdominal operations through natural orifices. The main limitation for a secure use of this technique is the lack of a proper surgical device, since it is still performed by non rigid endoscopes designed for diagnostic applications. Robot Assisted Surgery is the ideal solution to perform this kind of surgical operations. This research project is a preliminary study for the design of an endoscope, with variable stiffness in effort to provide the surgeons with a device which meets specific clinical requirements. The body is composed of a series of robotic modules connected by joints capable of two different movements: an axial rotation and a longitudinal bending. The movements are servo commanded and carried out by two brushless DC electric motors and an encoder. A force sensor is mounted on each module in order to provide a haptic feedback to the surgeon. The end point of the robot is equipped with a high definition camera which is able to perform zoom, autofocus and image stabilization. Illumination is provided by a power led system. A CAN bus ensures the communication between the modules, the camera and the haptic interface.

Commentary by Dr. Valentin Fuster
2011;():779-784. doi:10.1115/DETC2011-48027.

This paper describes the analysis of a novel microdroplet generator’s integrated sensing capability using finite element simulation. The dominant paradigm for utilizing droplet generation is with either open-loop or externally-sensed closed-loop methods, each with significant disadvantages in terms of reliability and large-scale implementation, respectively. This work utilizes a system designed with a compressible gas reservoir adjacent to the incompressible droplet liquid reservoir. The compressible gas pressure changes as liquid droplets are dispensed from the constant volume fluid reservoir. This change was found to be linearly dependent on the size of the droplet that was ejected, validating this gas reservoir pressure as a useful means of indirectly measuring droplet size internally within the system.

Commentary by Dr. Valentin Fuster
2011;():785-793. doi:10.1115/DETC2011-48031.

Socially assistive robots can engage in assistive human-robot interactions (HRI) by providing rehabilitation of cognitive, social, and physical abilities after a stroke, accident or diagnosis of a social, developmental or cognitive disorder. However, there are a number of research issues that need to be addressed in order to design such robots. In this paper, we address one main challenge in the development of intelligent socially assistive robots: A robot’s ability to identify human non-verbal communication during assistive interactions. In this paper, we present a unique non-contact automated sensory-based approach for identification and categorization of human upper body language in determining how accessible a person is to a robot during natural real-time HRI. This classification will allow a robot to effectively determine its own reactive task-driven behavior during assistive interactions. The types of interactions envisioned include providing reminders, health monitoring, and social and cognitive therapies. Preliminary experiments show the potential of integrating the proposed body language recognition and classification technique into socially assistive robotic systems partaking in HRI scenarios.

Topics: Robots
Commentary by Dr. Valentin Fuster
2011;():795-804. doi:10.1115/DETC2011-48039.

Variants of Fuzzy logic controllers (FLC) have been widely used to control the systems characterized by uncertain and ambiguous parameters. Control objectives for such systems become more challenging when they are subjected to uncertain environments. Human-robot interaction is such phenomenon wherein robot control difficulties are further augmented due to human intervention. State of the art of research in FLC has been limited in establishing a trade-off between accuracy and interpretability, since achieving both these performance measures simultaneously is difficult. In the present research, an adaptive FLC has been designed in order to achieve better accuracy and higher interpretability. Supported by another instance of FLC as disturbance observer, the proposed controller has adaptive mechanism specifically designed to alter its parameters. The adaptive FLC has been implemented to control actuation of a pneumatic muscle actuator (PMA). Experimental results show excellent trajectory tracking performance of the PMA in the presence of varying environment.

Commentary by Dr. Valentin Fuster
2011;():805-810. doi:10.1115/DETC2011-48095.

This paper is about fractional system identification of a thermal model of the lungs. Usually, during open-heart surgery, an extracorporeal circulation (ECC) is carried out on the patient. In order to plug the artificial heart/lung machine on the blood stream, the lungs are disconnected from the circulatory system. This may results in postoperative respiratory complications. A method to protect the lungs has been developed by surgeon and anesthetist. It is called: bronchial hypothermia. The aim is to cool the organ in order to slow down its deterioration. Unfortunately the thermal properties of the lungs are not well-known yet. Mathematical models are useful and needed in order to improve the knowledge of these organs. As proved by several previous works, fractional models are especially appropriate to model thermal systems (model compacity, accuracy) and the dynamic of fractal systems. Thus, fractional models of the lungs have been determined using time domain system identification with the Havriliak-Negami function. A comparison with integer order models was also carried out. The aim of this paper is to present the results of this study.

Topics: Lung
Commentary by Dr. Valentin Fuster
2011;():811-819. doi:10.1115/DETC2011-48704.

This paper describes the design, fabrication, and characterization of a differential scanning nanocalorimeter that has potential to significantly reduce the sample volume to microliter and improve the temperature sensitivity to 10 μK. The nanocalorimeter consists of a polymeric freestanding membrane, four high-sensitive low-noise thermistors based on the silicon carbide (SiC), and a platinum heater and temperature sensor. With the integrated heater and sensors, temperature scanning and power compensation can be achieved for calorimetric measurement. Temperature sensing SiC film was prepared by using sintered SiC target and DC magnetron sputtering under different gas pressure and sputtering power. The SiC sensing material is characterized through the measurement of current-voltage curves and noise levels. Thermal performance of a fabricated nanocalorimeter is studied in simulation and experiment. The results indicate the device has a nano watt thermal power sensitivity, 10 μK temperature sensitivity, and long time constant to hold thermal energy, which leads to low-volume ultra sensitive nanocalorimetry for biological process, such as protein folding and ligand binding.

Topics: Manufacturing , Design
Commentary by Dr. Valentin Fuster
2011;():821-827. doi:10.1115/DETC2011-48719.

Augmentation of osteoporotic bone with polymethylmethacrylate (PMMA) bone cement has been shown to be effective in reducing the risk of bone fracture. Injection of the highly viscous bone cement, however, is challenging mainly due to high injection forces required to maintain the nominal injection rates. Also, effective placement of the cement requires precise planning and execution. We are developing a surgical workstation for planning and executing proximal femur augmentation. As a crucial part of the framework, we have designed and fabricated a prototype automatic injection device that provides the substantial forces while maintaining the planned injection rates. Design parameters were determined based on the criteria available in the literature and our preliminary tests. Intended features for the device included high injection force capability, precisely controllable injection and ease of use. A number of calibration experiments were performed to ensure that the device meets the intended criteria. The device can be quickly set up before the surgical operation and can operate in manual or automatic placement configurations. The automatic injection device can also be used for a range of other orthopaedic applications involving direct augmentation of the bones or screws fixated in the bones.

Commentary by Dr. Valentin Fuster
2011;():829-845. doi:10.1115/DETC2011-47861.

In this paper, the vehicle platooning literature published between 1994 and 2010 is categorized and discussed. The paper includes a general introduction and overview of vehicle platooning and a technical description of the methodology. Recent trends in Vehicle Platooning are presented and discussed. The results are reviewed and the vehicle platooning literature is categorized into subcategories within the broader division of application focused and theory focused results. Issues and challenges faced in platooning are discussed.

Topics: Vehicles
Commentary by Dr. Valentin Fuster
2011;():847-855. doi:10.1115/DETC2011-48415.

Highly reconfigurable modular robots face unique teleoperation challenges due to their geometry, configurability, high number of degrees of freedom and complexity. Current methodology for controlling reconfigurable modular robots typically use gait tables to control the modules. Gait tables are static data structures and do not readily support realtime teleoperation. Teleoperation techniques for traditional wheeled, flying, or submerged robots typically use a set of joysticks to control the robots. However, these traditional methods of robot teleoperation are not suitable for reconfigurable modular robotic systems which may have dozens of controllable degrees of freedom. This research shows that modern cell phones serve as highly effective control platforms for modular robots because of their programmability, flexibility, wireless communication capabilities, and increased processing power. As a result of this research, a versatile Graphical User Interface, a set of libraries and tools have been developed which even a novice robotics enthusiast can use to easily program their mobile phones to control their hobby project. These libraries will be beneficial in any situation where it is effective for the operator to use an off-the-shelf, relatively inexpensive, hand-held mobile phone as a remote controller rather than a considerably heavy and bulky remote controllers which are popular today. Several usage examples and experiments are presented which demonstrate the controller’s ability to effectively control a modular robot to perform a series of complex gaits and poses, as well as navigating a module through an obstacle course.

Topics: Robots
Commentary by Dr. Valentin Fuster
2011;():857-862. doi:10.1115/DETC2011-47138.

Due to the high power density of supercapacitors, it is adopted in electric vehicles to essentially guarantee to recover more regenerative energy. However, there is still not a valid set of measurement methods to gauge the energy absorbed from regeneration system, the measurement and evaluation system for regenerative energy require to be investigated in order to estimate the performance of electric vehicles. Based on the analysis of the regenerative braking energy system of a supercapacitor truck, a measurement and evaluation system for recycling energy in the braking process is established. Meanwhile, the experiments of supercapacitor vehicle under various braking condition are carried out. The results show the effectiveness of the proposed braking energy recycling measurement method.

Commentary by Dr. Valentin Fuster
2011;():863-871. doi:10.1115/DETC2011-47804.

The present paper describes a design of speed control system of the water driven stage that has been developed for a feed table of an ultra-precision machine tool. The stage has a piston-cylinder mechanism to drive a table of the stage. Since the piston-cylinder mechanism is used, the flow rate supplied to the piston-cylinder controls the speed of the table. For diamond turning applications, the constant feed motion of the stage is highly desirable in order for obtaining fine diamond-turned surfaces. In the present paper, mathematical models of the water driven stage and a flow control valve are introduced. Based on the derived models, a conventional P-I control system is then designed in order to achieve desired control performances, aiming no steady-state error and minimized extraneous disturbance effects on the response. Performances of the designed controller are studied through experiments and simulations.

Commentary by Dr. Valentin Fuster
2011;():873-880. doi:10.1115/DETC2011-48403.

HELVIS (Hybrid Electric Vehicle In Low Scale) is a mini-HEV platform used on the research of HEVs (Hybrid Electric Vehicles), through which students of all degrees have the opportunity to be introduced to the universe that surrounds HEVs in many aspects. In this work the HELVIS-Sim is presented. HELVIS-Sim is a full dynamic & kinematic vehicular simulator for the HELVIS platform, consisting of a Simulink™ environment through which the states of a large number of variables related to the vehicle can be observed and analyzed. Specially in this paper, the focus is in the control of HELVIS EDS (Electronic Differential System), presenting classic, A.I.-based (Artificial Intelligence) and optimal robust controllers in the problem of the adjustment of the rear angular speeds. HELVIS-Sim results are then compared to experimental data obtained from the real HELVIS EDS, with the aid of a dSpace™ real time interface board.

Commentary by Dr. Valentin Fuster
2011;():881-887. doi:10.1115/DETC2011-48942.

In this paper, the technologies for electric vehicle wireless charging are reviewed including the inductive coupling, magnetic resonance coupling and microwave. Among them, the magnetic resonance coupling is promising for vehicle charging mainly due to its high efficiency and relatively long transfer range. The design and configuration of the magnetic resonance coupling based wireless charging system are introduced. A basic experimental setup and a prototype electric vehicle wireless charging system are developed for experimental and research purposes. Especially the prototype system well demonstrates the idea of fast and frequent wireless charging of supercapacitor electric vehicles using magnetic resonance coupling. Though the idea of wireless energy transfer looks sophisticated, it is proved to be a handy technology from the work described in the paper. However, both component and system-level optimization are still very challenging. Intensive investigations and research are expected in this aspect.

Commentary by Dr. Valentin Fuster
2011;():889-894. doi:10.1115/DETC2011-49013.

In this paper we present a traffic simulation system using traffic data gathered from readings by GPS devices installed on board of busses, i.e., busses running on the road are used as a mobile sensor network. Traffic data are inferred from the comparison of data about normal speed and current speed in a certain position. The simulation system was developed to invent mechanisms that use such information for traffic optimization. In particular, simulations allow to manage traffic lights in real time and to control the traffic system in order to give priority to public transportation systems.

Commentary by Dr. Valentin Fuster
2011;():895-900. doi:10.1115/DETC2011-47518.

This article demonstrates that many general forms of pre-compensators can be included in a Multi-Input-Multi-Output (MIMO) plant with a very general state-space description and the augmented plant can be reduced to static output feedback (SOF) form that is required for optimal design. The main contribution lies in solving very cumbersome algebraic matrix equations, for each configuration, to separate the unknown parameters after the optimal static output feedback gain matrix is achieved. Once the designers see that such configurations with chosen pre-compensators can be dealt with, they would be motivated to consider a suitable configuration for the specific application and finally achieve low cost controllers that are simple to implement and require low computational power.

Commentary by Dr. Valentin Fuster
2011;():901-908. doi:10.1115/DETC2011-47742.

Remote Sensing using unmanned aerial vehicles (UAV) is gathering a lot of attention at the moment by researchers and developers, especially in terms of low-cost aircrafts which still maintain sufficient accuracy and performance. This paper introduces a low-cost approach to increase airworthiness by using a forward-looking camera to estimate the attitude of a UAV. It not only focuses on using machine learning to classify ground and sky, but also uses image processing and software engineering methods to make it fault-tolerant and really applicable on a miniature UAV. Additionally, it is able to interface with an autopilot framework to being used productively on flight missions.

Commentary by Dr. Valentin Fuster
2011;():909-916. doi:10.1115/DETC2011-47844.

Small unmanned aerial vehicles (UAVs) can provide facilities in various applications. Compared with single UAV system, small UAVs based cooperative UAV system can bring advantages such as higher efficiency and safety. Therefore, it is necessary to design a robust multi-agent cooperative flight controller to coordinate a group of small UAVs for stable formation flights. This paper investigates the problem of consensus-based formation control for a multi-UAV system. Firstly, We choose a simplified model with nonholonomic constraints for UAV dynamics. Secondly, using the algebraic theory and backstepping technique, we design consensus protocols for multi-UAV systems under the strongly connected topology. Then based on that, we propose a multi-UAVfromation control strategy. Finally, we extend our results to the directed topology case which is still effective by simulation.

Commentary by Dr. Valentin Fuster
2011;():917-927. doi:10.1115/DETC2011-47848.

Cooperative UAV systems can have great advantages over isolated UAV systems, regarding application, safety, efficiency and many other perspectives. Motivated by challenges from practical multiple UAV formation flight, this paper presents our approaches towards cognitive formation flight. It introduces the principle ofmulti-UAV cognitive formation flight and the control structure utilized in our development, describes a low-cost UAV testbed developed by ourselves, and details the tuning procedures of the implemented multi-agent flight controller for stable and consistent formation flights. Different formation flight scenarios are also discussed and the experimental setup is presented including real-time issues and the formation flight test protocol. Routinized comprehensive flight test results are also shown at the end.

Commentary by Dr. Valentin Fuster
2011;():929-936. doi:10.1115/DETC2011-47851.

Radio control (RC) aircrafts have been favorite toys of aviation hobbyists for years. Because of their simple configurations and low expense, they can also be used for reconnaissance and surveillance with information-gathering devices under commands of a skillful human pilot. However, control with human in the loop not only degrades the reliability of the flight performance, but also bring restrictions in endurance and accuracy. In order to resolve these issues and extend the usage of RC aircrafts, getting them capable of autonomous navigation is a preferred solution. This paper reports our approach by designing and integrating an autonomous system on a regular RC aircraft to achieve full autonomy while keeping the additional costs almost equivalent to the cheap RC platform. The current platform will be briefly presented, the system architecture and major components will be introduced, and detailed autonomous demonstration flight results will be provided at the end.

Topics: Aircraft
Commentary by Dr. Valentin Fuster
2011;():937-943. doi:10.1115/DETC2011-48167.

Remote sensing is a field traditionally dominated by expensive, large-scale operations. This paper presents our efforts to improve our unmanned aircraft (UA) platforms for low-cost personal remote sensing purposes. Safety concerns are first emphasized regarding the local airspace and multiple fail-safe features are shown in the current system. Then the AggieAir unmanned system architecture is briefly described including the Paparazzi UA autopilot, AggieAir JAUS implementation, AggieNav navigation unit and payload integration. Some preliminary flight test results and images acquired using an example thermal IR payload system are also shown. Finally Multi-UAV and heterogeneous platform capabilities are discussed with respect to their applications. Based on our approaches on the new architecture design, personal remote sensing on smaller-scale operations can be more beneficial and common.

Topics: Safety , Flight
Commentary by Dr. Valentin Fuster
2011;():945-953. doi:10.1115/DETC2011-48259.

This paper provides a survey on different kinds of prediction models developed for the estimation of soil moisture content of an area, using empirical information including meteorological and remotely sensed data. The different models employed extend over a wide range of machine learning techniques starting from Basic Linear Regression models through models based on Bayesian framework, Decision tree learning and Recursive partitioning, to the modern non-linear statistical data modeling tools like Artificial Neural Networks. The fundamental mathematical backgrounds, pros and cons, prediction results and efficiencies of all the models are discussed.

Topics: Soil
Commentary by Dr. Valentin Fuster
2011;():955-962. doi:10.1115/DETC2011-48447.

In this work the synthesis of a MIMO (Multiple Input Multiple Output) robust optimal model-based H∞ controller is proposed. The whole process takes into account the dynamic equations of a 2-DoF quadrotor Mini Aerial Vehicle (MAV) attached to a steel stand. We consider the gamma-iteration algorithm to find the controller. Our analysis focuses on the control of roll and pitch axes, thereby neglecting the yaw axis control. As our goal is, a priori, to observe the behavior of the H∞ controller while it is controlling the four motors individually in order to stabilize our MAV, this set up provides us with the possibility of a very close overview of the aircraft. Indeed, it allows the easy insertion of disturbances in both axes (individually and simultaneously) and then closely observe the behavior of the platform. Besides, and most important at any laboratory environment, it is an extremely safe mode to run indoor tests, avoiding the quadrotor from causing harm to the crew if any technical problem occurs. The optimal H∞ robust controller presents a high capability of rejecting noises and disturbances. The controller can also suppress the uncertainties of our model. Besides presenting the dynamical model of our MAV, we present the experimental results of both roll and pitch control using the dSpace™ 1103 high performance controller board to embed the designed H∞ MIMO controller.

Commentary by Dr. Valentin Fuster
2011;():963-971. doi:10.1115/DETC2011-48561.

This paper presents the development of a guidance system for a small Unmanned Aerial Vehicle (UAV) system which combines a waypoints following and an obstacle avoidance systems so that the UAV has a capability to operate in an environment whose ground condition is not completely known. The waypoints following system works by adopting the VOR-Hold approach, in which a correction command will be produced to reduce the angle difference between the desired path and the line connecting the actual UAV position and the subsequent destination point. An avoidance algorithm is developed and integrated with the path following system. In case of the UAV faces an obstacle lying on its flight path, then the avoidance system will generate a set of new waypoints for correcting the flight path, so that the UAV can avoid the obstacle and then returns to the previous flight path. The proposed avoidance approach bases its algorithm on the utilization of ellipsoid geometry for defining a restricted zone containing the obstacle, which is assumed to be already identified by the detection system. When the restricted ellipsoid zone has already been established, the algorithm then computes the locations of new waypoints on the edge of the ellipsoid. The algorithm then is simulated and evaluated in some cases representing situations when an UAV has to avoid obstacles during its flight to a predefined destination.

Commentary by Dr. Valentin Fuster
2011;():973-981. doi:10.1115/DETC2011-48606.

This paper describes the integration and test work of a small unmanned aerial vehicle (UAV) with autopilot capability, which is currently being developed at New Mexico State University. The UAV is an integration of a commercially available autopilot system (Micropilot’s MP2128HELI ) with an RC helicopter (Raptor 90). It has been found quite challenging to integrate an autopilot system with a hobby RC helicopter for research purpose because hobby airframes, as low-cost and manually operated toys, were not designed readily for working with delicate and sensitive autopilot electronics. In our case, the strong vibration disturbances from the gas engine and other moving parts of the airframe significantly corrupted the signals from the avionics hardware. Innovative vibration isolation technique has been developed to mechanically isolate the vibrations from affecting the autopilot system. Several other key problems related to electromagnetic interference shielding and safe flight test were also effectively solved on the project. The integration work has been completed and the UAV is currently being tested.

Topics: Autopilots
Commentary by Dr. Valentin Fuster
2011;():983-989. doi:10.1115/DETC2011-48644.

A vision-based servoing technique is proposed for a 2 degrees-of-freedom (dof) model helicopter equipped with a monocular vision system. In general, these techniques can be categorized as image- and position-based, where the task error is defined in the image plane in the former and in the physical space in the latter. The 2-dof model helicopter requires a configuration-dependent feed-forward control to compensate for gravitational forces when servoing on a ground target. Therefore, a position-based visual servoing deems more appropriate for precision control. Image information collected from a ground object, with known geometry a priori, is used to calculate the desired pose of the camera and correspondingly the desired joint angles of the model helicopter. To assure a smooth servoing, the task error is parameterized, using the information obtained from the linearaized image Jacobian, and time scaled to form a moving reference trajectory. At the higher level, a Linear Quadratic Regulator (LQR), augmented with a feed-forward term and an integrator, is used to track this trajectory. The discretization of the reference trajectory is achieved by an error-clamping strategy for optimal performance. The proposed technique was tested on a 2-dof model helicopter capable of pitch and yaw maneuvers carrying a light-weight off-the-shelf video camera. The test results show that the optimized controller can servo the model helicopter to a hovering pose for an image acquisition rate of as low as 2 frames per second.

Topics: Design , Errors
Commentary by Dr. Valentin Fuster
2011;():991-996. doi:10.1115/DETC2011-48651.

This paper investigates the problem of covering an environment using a group of quadrotor Unmanned Aerial Vehicles (UAVs) based on locational optimization techniques to assign Voronoi regions to vehicles. In comparison with the standard coverage control problems for single integrator agents, we design a planar position controller for UAVs to spread out over an environment to provide coverage. The stability of entire system is guaranteed using LaSalle’s invariance principle, and numerical simulation is provided to show the effectiveness of the proposed method.

Commentary by Dr. Valentin Fuster
2011;():997-1004. doi:10.1115/DETC2011-48755.

This paper proposes a useful approach to Fault Tolerant Control (FTC) based on the Model Reference Adaptive Control (MRAC) technique with application to a quadrotor helicopter Unmanned Aerial Vehicle (UAV) in hovering as well as trajectory tracking flight in order to control and keep the desired height and trajectory of the quadrotor helicopter in both normal conditions and in the presence of faults in one or more actuators. A Linear Quadratic Regulator (LQR) controller is used in cooperation with the MRAC to control the pitch and roll attitude of the helicopter. Three cases of fault are considered: 1) simulated fault in all the four actuators; 2) simulated fault in back and right motors; 3) a physical damage of 23% of one of the four propellers during autonomous flight. It can be seen from the test results that under the faulty and damage conditions MRAC controller provided a good response of the quadrotor UAV and result in safe landings of the quadrotor.

Commentary by Dr. Valentin Fuster
2011;():1005-1012. doi:10.1115/DETC2011-48788.

The integrated fault diagnosis and fault-tolerant control problem is studied in this paper for linear systems subject to control input constraints. By using an adaptive observer to estimate the constant actuator fault magnitudes and the states simultaneously, a feedback controller is designed to stabilize the closed-loop system. With upper bounds of the fault amplitudes being proportional to the control limits, the admissible initial conditions and estimation errors are given and bounded by a contractively invariant ellipsoidal set. Matrix conditions are presented for the design of both observer and controller. For computation of the controller gain, a nonlinear programming algorithm is proposed. The ADMIRE (Aero Data Model In Research Environment) model is used to verify the effectiveness of the proposed design techniques.

Commentary by Dr. Valentin Fuster
2011;():1013-1022. doi:10.1115/DETC2011-48806.

In this paper, two sliding mode based fault tolerant control (SM-FTC) strategies are designed, implemented and flight-tested in a physical quadrotor unmanned helicopter under the propeller damage and actuator fault conditions. Sliding model control (SMC) is well known for its capability of handling uncertainty and is expected to be a robust controller. Based on the concept of sliding mode control, both passive and active fault tolerant controls have been designed and experimentally tested on a quadrotor UAV (unmanned aerial vehicle) test-bed, known as Qball-X4, available at Concordia University in the presence of actuator faults and propeller damages. These two types of controllers are carried out and compared through theoretical analysis, simulation, and experimental flight tests on the quadrotor UAV system. Good control performance has been achieved in the presence of actuator faults and propeller damages.

Commentary by Dr. Valentin Fuster
2011;():1023-1030. doi:10.1115/DETC2011-48836.

Accurately modeling the dynamic characteristics of a helicopter is difficult and time-consuming. This paper presents a new identification approach which applies the modes partition method and structure traversal (MPM/ST) algorithm. The dynamic modes, instead of model parameters of each model structure, are sequentially identified through MPM. The model with the minimum cost function (CF) is chosen from the best model set and is defined as the final model. Real flight tests of an unmanned helicopter are carried out to verify the identification approach. Time- and frequency-domain results of the identified models clearly demonstrate the potential of MPM/ST in modeling such complex systems.

Commentary by Dr. Valentin Fuster
2011;():1031-1035. doi:10.1115/DETC2011-48954.

In order to develop a backup navigation scheme for allowing temporally GPS faults or degradations, this paper proposes a dynamic key-frame-based natural-landmark scene matching visual navigation method for UAV. Firstly, this method could autonomously describe and check featured natural landmarks by analyzing image sequence from on-board camera. Secondly, After abstraction of key-frames including featured natural landmark, UAV will be located by the means of NLSM (Natural-Landmark Scene Matching) which based on dynamic key-frame. Thirdly, this navigation scheme adopt inter-frame scene matching algorithm in order to improving the navigation performance of accuracy, reliability and runtime. Experiments show that the vision navigation scheme proposed fits the requirements of navigation in complex and unknown environment for UAV.

Commentary by Dr. Valentin Fuster
2011;():1037-1046. doi:10.1115/DETC2011-48975.

In this paper, a robust control algorithm, based on sliding modes techniques, designed for trajectory tracking is applied to a fixed-wing small Autonomous Aerial Vehicle (AAV). Based on a mathematical modeling, parameters identification, and aerodynamics of both the AAV fuselage and its mobile surfaces a full dynamical model is obtained, where the control is proven. However, for control design, simplified versions of the motion models are studied resulting in simplified independent controller for the roll, pitch and yaw trajectories. Due to the nature of such controller, time derivative of control variables are needed but not available. Numerical differentiators also based on sliding modes are used in order to estimate those derivatives. Simulation results are given to illustrate the performance of the proposed tracking controller under parametric and unmodeled dynamics.

Commentary by Dr. Valentin Fuster
2011;():1047-1052. doi:10.1115/DETC2011-49012.

In this paper a mixed vision-range based approach, based on Kinect technology, for safe landing of an Unmanned Aerial Vehicle (UAV) is proposed. The guidance system allows a remote user to define target areas from an high resolution aerial or satellite image to determine the waypoints of the navigation trajectory or the landing area. The system is based on our previous work on UAV navigation and landing: a feature-based image matching algorithms finds the natural landmarks and gives feedbacks to the control system for autonomous navigation and landing. An algorithm for safe landing areas detection is proposed, based on the use of 4D RGBD (Red, Green, Blue, Distance) image analysis. The helicopter is required to navigate from an initial to a final position in a partially known environment, to locate a landing area and to land on it. Results show the appropriateness of the vision-based approach that does not require any artificial landmark (e.g., helipad) and is quite robust to occlusions, light variations and high vibrations.

Commentary by Dr. Valentin Fuster

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