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ASME Conference Presenter Attendance Policy and Archival Proceedings

2017;():V009T00A001. doi:10.1115/DETC2017-NS9.
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This online compilation of papers from the ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2017) 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presenter attendance policy, if a paper is not presented at the Conference by an author of the paper, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.

Commentary by Dr. Valentin Fuster

13th ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Autonomous Systems and Ambient Intelligence (ASAI)

2017;():V009T07A001. doi:10.1115/DETC2017-67355.

In comparison with the traditional controller PID, the fractional order controller PIλDμ is added with two parameters (μ and λ), that increases the flexibility of the controller. The larger adjustable space makes it more favorable to the control of the nonlinear system like the three-phase grid-connected inverter. However, since the fractional calculus operator is an irrational function on the complex plane, it can’t be implemented directly in simulation or in practical applications. In this paper, the advantages of the fractional order controller PIλDμ will be analyzed, then the fractional calculus operator is fitted by the frequency domain analysis method. Based on the vector method, the fractional order controller PIλDμ of the grid-connected inverter is designed. Simultaneously, the optimal controller parameters are searched with the ITAE and IAE as the performance index. And finally, the results are compared with those of the traditional controller PID. In consideration of the defects of fractional algorithm and single discretization method, a hybrid discretization method is proposed in order to ensure that the discretized controller can keep the same time-domain response and frequency characteristics as the designed controller. The experimental results show that the proposed method has the dynamic and static characteristics better than the traditional controller PID, which proves that the application of fractional order controller in three-phase grid-connected inverter is effective and feasible.

Commentary by Dr. Valentin Fuster
2017;():V009T07A002. doi:10.1115/DETC2017-67760.

An active fault tolerant control technique for Underwater Remotely Operated Vehicles is proposed in this paper. The main objective is to develop a controller for the tracking problem, which is robust against possible actuator faults and failures. The main advantage of the proposed fault tolerant control scheme is to develop a unique controller, and thus a unique set of control parameters, regardless the presence of faults and failures. This is achieved through a redistribution of the control effort on the healthy actuators. Simulation results are provided to demonstrate the viability of the proposed fault accommodating technique.

Commentary by Dr. Valentin Fuster
2017;():V009T07A003. doi:10.1115/DETC2017-68004.

Vehicle tracking and classification algorithms that remain robust under illuminations changes and occlusions remain a challenging task for vehicle recognition systems. A vehicle which reappears in the scene after disappearing behind an obstacle or a bigger vehicle has to re-obtain the previous identification number assigned by the system. In other circumstances, two or more vehicles overlapping each other are recognized by the system as a single entity: for this reason, after splitting, the system has to reassign pending identification numbers to the respective vehicles. In this paper we propose a three steps (vehicle identification with removal of headlight reflections, tracking with occlusion management and classification with size and speed estimation) algorithm operating in presence of illumination changes, reflections and occlusions. The experimental results obtained by processing a video recorded from a static camera show that the approach is able to successfully manage occlusions in over 90% of cases and to satisfactory classify vehicles into four classes, depending on their length/dimension.

Topics: Vehicles
Commentary by Dr. Valentin Fuster
2017;():V009T07A004. doi:10.1115/DETC2017-68016.

Earlier diagnosis plays a pivotal role in clinical applications, since it can strongly reduce the incidence and impact of many diseases and, consequently, the reduction of health care costs. This last aspect depends strongly from right therapy prescriptions, especially when there are various opportunities. Within this context, Clinical Decision Support Systems (CDSS) could bring several benefits. In this paper, we propose a CDSS with the aim of improving the clinician practice based on recommendations, assessment of the patient and screening of patients with risk factors to prevent chronic venous insufficiency (CVI) complications. The proposed CDSS is implemented in the Nu.Sa. cloud system, which involves thousands of italian General Practitioners (GPs) collecting data (EHR data, personal data, patient’s medical history) from millions of patients. The proposed architecture is designed to collect data from a distributed scenario where GPs are collecting clinical history and pharmacy or second level hospitals gather data from medical devices connected to the cloud over a standard data architecture. We show that exploiting the integration of the medical device VenoScreen Plus with the patient EHR, this CDSS is capable to improve preventive care, to enhance clinical performance, to influence clinical decision making and to significantly improve the decision quality levering on data driven approach.

Commentary by Dr. Valentin Fuster

13th ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Design and Verification Methodologies for Mechatronic and Embedded Systems

2017;():V009T07A005. doi:10.1115/DETC2017-67402.

New applications relying on embedded systems technologies often come with an increased number of features and functionalities. For instance, improved safety, reliability, usability or reduced power consumption are commonly encountered aspects. Those in turn, however, come usually at the cost of increased complexity. Managing the latter can become challenging, especially when looking at (worst-case) execution times or memory usage of embedded systems. In particular, many applications, e.g., safety-critical or real-time applications, require knowledge about the worst-case execution time and stack usage to make a clear statement on important system parameters such as the overall performance or schedulability with regard to critical deadlines. Assessing these properties require elaborate tool support and profound knowledge and skills of the developers. In this paper, an evaluation of static analysis tools and the required steps to integrate these in a existing development environment is presented. The toolchain is either considered to be offline or deployed within a cloud-based integrated development environment. The cloud-approach enables ubiquitous access to the results and a unique visualization across multiple platforms. Additionally, the results are demonstrated along with a small use case.

Commentary by Dr. Valentin Fuster
2017;():V009T07A006. doi:10.1115/DETC2017-67422.

Embedded systems technologies are at the core of many products and applications, for example, ones as used in smart homes or modern cars. These technologies enable new functional features which in turn improve also non-functional aspects such as environmental efficiency. Especially, their inter-connection and coupling with existing networks — here in particular to the internet — allows for an unprecedented boost. At the same time security concerns become consequential since respective security breaches may have dire consequences that range from theft and/or tampering of intellectual property over to malfunctions that can result in threats of safety. This paper presents a survey of software approaches used to prevent reverse engineering, defend against malicious modifications, and to ensure integrity of embedded systems software. The presented methods focus on mechanisms for post development stages that can be used to add/improve security features of existing products. Furthermore, different kind of targets are taken into consideration, separating the introduced security features in regard to their applicability for standalone and OS-based embedded systems.

Commentary by Dr. Valentin Fuster
2017;():V009T07A007. doi:10.1115/DETC2017-67515.

The traction characteristics of a half-toroidal variator system were quantitatively identified. The rheological characteristics of the traction fluid dependent on applied pressure, slip rate, and traction surface temperature were identified from experimental data and finite element analysis using a four-roller machine. Half-toroidal variator system operation should take into account a safety factor, so the variator M versus slip characteristic was clarified by combining a half-toroidal variator model with the identified traction fluid characteristics. This method enabled to quantify the variator M-slip characteristic and power transmission efficiency of a half-toroidal variator in advance, and also enabled visualization of the spinning behavior due to the traction surface frictional force.

Topics: Traction
Commentary by Dr. Valentin Fuster
2017;():V009T07A008. doi:10.1115/DETC2017-68412.

In hard real-time and embedded multiprocessor system real-world applications, it is very important to strive to minimize the run-time overhead of the scheduler as much as possible, especially in hard real-time and embedded multiprocessor systems with limited processor and system resources. In this paper, we present a method that reduces the worst-case time complexity of the run-time scheduler for re-computing latest start times and for selecting processes for execution on a multiprocessor at run-time to O(n), where n is the number of processes.

Commentary by Dr. Valentin Fuster

13th ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Disturbance Rejection Control

2017;():V009T07A009. doi:10.1115/DETC2017-67095.

This paper aims to rigorously study the observer for general uncertain systems. The proposed observer is shown to be the general form of extended state observer (ESO), disturbance observer (DO), generalized extended state observer (GESO) and extended high gain observer (EHGO). The properties of this general observer is discussed by analyzing the estimation error. The paper illustrates that the output of the proposed general observers may not performs as the estimation the real state and uncertainty. We prove that this observer gives the estimations for the group of states and uncertainties whose exact form is given in the paper. Finally, numerical simulations for a typical example validate the theoretical analysis.

Commentary by Dr. Valentin Fuster
2017;():V009T07A010. doi:10.1115/DETC2017-67096.

This paper presents a comprehensive framework for developing a novel time-varying spectrum based active disturbance rejection control (TVS-ADRC) technique. It complements conventional linear or nonlinear ADRC by introducing time-varying components, including time-varying extended state observer, time-varying tracking differentiator, and time-varying feedback, to offer better design flexibility and improved performance in command filtering, disturbance observation, and closed-loop control. First, skeleton stability and convergence analysis is introduced based on differential algebraic spectral theory. Then parameter tuning is categorized into two time-varying principles: a time-based profile and a state-dependent function, and a unified parameterization approach is given by assigning time-varying eigenvalues. Typical applications are pointed out which demonstrate great advantages of TVS-ADRC in consideration of varying plant or environment features and physical limits in practical systems. Challenges and future work for the TVS-ADRC technique are also summarized in the end.

Commentary by Dr. Valentin Fuster
2017;():V009T07A011. doi:10.1115/DETC2017-67114.

Disturbance observer (DOB) based control has been widely applied in industries due to its easy usage but powerful disturbance rejection ability. However, the existence of innate structure constraint, namely the inverse of the nominal plant, prevents its implementation on more general class of systems, such as non-minimum phase plants, MIMO systems etc.. Furthermore, additional limitations exerted on Q-filter design, i.e., unity steady state gain and low-pass nature, which narrow down its solution space largely and prevent from achieving optimal performance even if it exists. In this paper, we present a novel DOB architecture, named generalized disturbance observer (G-DOB), with the help of nontraditional use of the celebrated Youla parametrization of two degree-of-freedom controller. Rigorous analyses show that the novel G-DOB not only inherits all the merits of the conventional one, but also alleviates the limitations stated before partially. By some appropriate system manipulation, the synthesis of Q-filter has been converted to the design of reduced-order controller. Thus, a heuristic two-stage algorithm has been developed with the help of Kalman-Yakubovich-Popov (KYP) lemma: firstly design a full information controller for the augmented system and then compute a reduced-order controller. Numerical examples are presented to demonstrate the effectiveness of the proposed G-DOB structure and design algorithm.

Topics: Algorithms
Commentary by Dr. Valentin Fuster
2017;():V009T07A012. doi:10.1115/DETC2017-67119.

Although active disturbance rejection control (ADRC) has demonstrated promising results in many applications, in some safety critical applications e.g. power plant, unmanned aerial vehicle, etc., it is often reluctant to switch from an existing control algorithm, either the traditional PID controller or other advanced control algorithms, to a new one. If the switching between the control algorithms can be made seamless, many more opportunities may open up. In this paper, the problem of making the switching to the ADRC smooth is studied. Previous attempts to solve the problem are not thorough enough, since only a second order system was addressed. A very simple and effective method is proposed based on analysis to make the transition seamless. The solution is very general, and can be applied to system of any order or even system with time-delay. At the core of the solution is the initialization of the “total disturbance”.

Commentary by Dr. Valentin Fuster
2017;():V009T07A013. doi:10.1115/DETC2017-67122.

It is difficult to control the output voltage of the Solid Oxide Fuel Cells (SOFCs) because of the system nonlinearity, load disturbance and various constraints on the actuators and the fuel utilization rate. To overcome these difficulties, this paper proposed a multiple model predictive control scheme. The nonlinearity is addressed by using multiple models that are linearized at different operating conditions. The disturbance is accommodated by directly sending the load current information to the optimizer. And the constraints are naturally handled by formulating a constrained optimization problem. The simulation results show the effectiveness of the proposed strategy.

Commentary by Dr. Valentin Fuster
2017;():V009T07A014. doi:10.1115/DETC2017-67126.

In this article, the output reference trajectory tracking control of a non-differentially flat, underactuated, system is approached from the perspective of Active Disturbance Rejection Control (ADRC) including a suitable Extended State Observer (ESO). The class of underactuated systems, which are non-differentially flat, constitutes the most challenging area for testing the effectiveness of robust feedback control algorithms, specially under output trajectory tracking requirements. The problem, however, is substantially alleviated and feasibly approached provided the tangent linearization of the system is found to be controllable around an arbitrary equilibrium point. The flatness of the tangent system is taken advantage of for the design of an observer-based feedback controller taking the tangent system operation substantially far from the operating point. The ADRC scheme robustly takes efficient care of the excited (endogenous) nonlinearities, which were neglected in the linearization process, as well as any other external (exogenous) disturbances. Here, we take the gantry crane and its closely associated system: the inverted pendulum on a cart, as working laboratory examples to illustrate the effectiveness of the proposed approach.

Commentary by Dr. Valentin Fuster
2017;():V009T07A015. doi:10.1115/DETC2017-67127.

Linear active disturbance rejection control (LADRC) has been paid much attention in academic and industrial fields. However, the selection of the order for LADRC controller design and the choice of parameter b0 in system correcting are key facts which are still being faced by designer. In this paper, an effective method about how to select the order of LADRC and the parameter b0 is given first. Frequency analysis often used by engineers for designing controller, the normal transfer function form of LADRC is constructed, so the loop gain, close loop transfer function and disturbance transfer function to a general high-order system are presented and can be easily used. The example shows that the proposed method is easy to apply and verified the lower-order LADRC can obtain the better effective than PID and high-order LADRC, and the frequency response analysis of a thermal power plant is elaborated and the simulation result indicates that LADRC has a strong robustness against the large variation of parameters in the plant mode.

Commentary by Dr. Valentin Fuster
2017;():V009T07A016. doi:10.1115/DETC2017-67131.

The ascent trajectory tracking problem of a launch vehicle is investigated in this paper. To improve the conventional trajectory linearization method which usually omits the linearization errors, the extended state observer (ESO) is employed in this paper to timely estimate the total disturbance which consists of the external disturbances and the modeling uncertainties resulting from linearization error. It is proven that the proposed trajectory tracking controller can guarantee the desired performance despite both external disturbances and the modeling uncertainties. Moreover, compared with the conventional linearization control method, the proposed controller is shown to have much better performance of uncertainty rejection. Finally, the feasibility and performance of this controller are illuminated via simulation studies.

Commentary by Dr. Valentin Fuster
2017;():V009T07A017. doi:10.1115/DETC2017-67148.

This paper proposes a linear active disturbance rejection control (LADRC) for gird-connected inverter with LCL filter to deal with parameters variation, internal coupling and external disturbance. Relative degree of plant is used to design LADRC and on the basis of relationship between LADRCs parameters and bandwidth, the parameters tuning are sum up in several guidable points. It is demonstrated that LADRC presents a good dynamic performances, high disturbance rejection and extremely robust to parameters variation in Matlab/Simulink.

Topics: Filters
Commentary by Dr. Valentin Fuster
2017;():V009T07A018. doi:10.1115/DETC2017-67444.

Generalized separation principle (GSP) is a main reason why active disturbance rejection control (ADRC) is easy to use. In this short note, GSP is interpreted from the respective of robust control. Linear active disturbance rejection control (LADRC) is described as an interconnection of two subsystems, while to design LADRC is a process to tuning the gains of them. Small gain theorem guarantees separately tuning is possible. That is why GSP works.

Commentary by Dr. Valentin Fuster
2017;():V009T07A019. doi:10.1115/DETC2017-67659.

The control of pure feedback system, which is widely used but has non-affine property, has always been an important and challenging problem. In order to achieve precise tracking control of pure feedback system through improving the disturbance rejection ability of existing reinforcement learning algorithm, a reinforcement learning (RL) control strategy based on extended state observer (ESO) is proposed in this paper. In the proposed method, the extended state observer can reject the total disturbances and transform the pure feedback system which is in an input-output predictor from to overcome the non-causal problem into a cascade integral form. This allows the continuous reinforcement learning strategy of the actor-critic (AC) structure not to depend on the detailed model information, which makes it practically data-driven. It is worth noting that, in order to further improve the ability to track the changing reference trajectory, a novel curvature acceleration factor is proposed, which can adjust the learning speed of the reinforcement learning controller according to the curvature of the reference trajectory. The validity of the proposed algorithm is verified by the simulation results.

Topics: Feedback
Commentary by Dr. Valentin Fuster

13th ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Fractional Derivatives and Their Applications (FDTA)

2017;():V009T07A020. doi:10.1115/DETC2017-67070.

For those surface mounted permanent magnet synchronous motors (PMSM), a fractional order phase lock loop (FO-PLL) sensorless control method is proposed. On the basis of PMSM model in stationary coordinate, a rotor flux linkage observer is constructed. By designing the modified integrator and introducing the high pass filter, output saturation distortion or numeric overflow caused by integrator zero drift are solved. The observing results have no DC component. Moreover, a fractional order PLL is designed to estimate the PMSM rotor angle and speed. Parameters of FO-PLL controller are tuned and optimized via ITAE criterion. System indiscrimination degree is improved effectively. By using Oustaloup recursive filter, high order integer order approximation to fractional order integrator is realized. Last, the effectiveness and engineering application of the proposed method are verified on a MATLAB based PMSM control simulation platform.

Commentary by Dr. Valentin Fuster
2017;():V009T07A021. doi:10.1115/DETC2017-67097.

This paper is devoted to the development of approximation method for numerical solution of basic boundary-contact problems of coupled thermo-elasticity in the Green-Lindsay formulation. In particular, we consider a static system of partial differential equations for two-dimensional isotropic inhomogeneous elastic materials in assumptions that surfaces are sufficiently smooth. The tools applied in this development are based on singular integral equations, the potential method and the generalized Fourier series analysis.

Topics: Approximation
Commentary by Dr. Valentin Fuster
2017;():V009T07A022. doi:10.1115/DETC2017-67099.

Generally speaking, definite conditions of fractional differential equations with Riemann-Liouville, Riesz or Hadamard fractional derivatives are quite different from those of classic differential equations. In this paper, we propose the well-posed conditions for fractional differential equation involving right Riemann-Liouville, Riesz and Hadamard fractional derivatives.

Commentary by Dr. Valentin Fuster
2017;():V009T07A023. doi:10.1115/DETC2017-67110.

Intensity inhomogeneity or weak texture region image segmentation plays an important role in computer vision and image processing. RSF (Region-Scalable Fitting) active contour model has been proved to be an effective method to segment intensity inhomogeneity. However RSF model is sensitive to the initial location of evolution curve , it tends to fall into local optimal. Aiming at the problem, this paper proposed a new method for image segmentation based on fractional differentiation and RSF model. The proposed method adds the global Grünwald-Letnikov fractional gradient into the RSF model. Thus the gradient of the intensity inhomogeneity and weak texture regions is strengthened. As a result, both the robustness of initial location of evolution curve and efficiency of image segmentation are improved. Theoretical analysis and experimental results demonstrate that the proposed algorithm is capable of segmenting the intensity inhomogeneities and weak texture images. It is robust to curve initial location, furthermore the efficiency of segmentation is improved.

Commentary by Dr. Valentin Fuster
2017;():V009T07A024. doi:10.1115/DETC2017-67129.

In this paper, the literature of fractional-order neural networks is categorized and discussed, which includes a general introduction and overview of fractional-order neural networks. Various application areas of fractional-order neural networks have been found or used, and will be surveyed and summarized such as neuroscience, computational science, control and optimization. Recent trends in dynamics of fractional-order neural networks are presented and discussed. The results, especially the stability analysis of fractional-order neural networks, are reviewed and different analysis methods are compared. Furthermore, the challenges and conclusions of fractional-order neural networks are given.

Commentary by Dr. Valentin Fuster
2017;():V009T07A025. doi:10.1115/DETC2017-67283.

This paper presents a FOPID tuning method for disturbance reject control by using multi-objective BB-BC optimization algorithm. Proposed method allows multi-objective optimization of set-point performance and disturbance rejection performances of FOPID control system. The objective function to be minimized is composed of the weighted sum of MSE for set-point performance and RDR for disturbance rejection improvement. The proposed optimization performs maximization of RDR and minimization of MSE and it can deal with the tradeoff between RDR performance and step-point performance. Application of the method is shown for auto-tuning of FOPID controller that is employed for control of TRMS model. We observed that low-frequency RDR indices can be used to improve disturbance rejection performance in multi-objective controller tuning problems. Particularly, for flight control application, disturbance reject control is very substantial to robust performance of propulsion systems.

Commentary by Dr. Valentin Fuster
2017;():V009T07A026. doi:10.1115/DETC2017-67479.

This paper is concerned with the fractional-order fault-tolerant tracking control design for unmanned aerial vehicle (UAV) in the presence of external disturbance and actuator fault. Based on the functional decomposition, the dynamics of UAV is divided into velocity subsystem and altitude subsystem. Altitude, flight path angle, pitch angle and pitch rate are involved in the altitude subsystem. By using an adaptive mechanism, the fractional derivative of uncertainty including external disturbance and actuator fault is estimated. Moreover, in order to eliminate the problem of explosion of complexity in back-stepping approach, the high-gain observer is utilized to estimate the derivatives of virtual control signal. Furthermore, by using a fractional-order sliding surface involved with pitch dynamics, an adaptive fractional-order fault-tolerant control scheme is proposed for UAV. It is proved that all signals of the closed-loop system are bounded and the tracking error can converge to a small region containing zero via the Lyapunov analysis. Simulation results show that the proposed controller could achieve good tracking performance in the presence of actuator fault and external disturbance.

Commentary by Dr. Valentin Fuster
2017;():V009T07A027. doi:10.1115/DETC2017-67483.

Strong coupling between values at different time that exhibit properties of long range dependence, non-stationary, spiky signals cannot be processed by the conventional time series analysis. The ARFIMA model, which employs the fractional order signal processing techniques, is the generalization of the conventional integer order models — ARIMA and ARMA model. Therefore, it has much wider applications since it could capture both short-range dependence and long range dependence. For now, several software have developed functions dealing with ARFIMA processes. However, it could be a big difference, if using different numerical tools for time series analysis. Time to time, being asked about which tool is suitable for a specific application, the authors decide to carry out this survey to present recapitulative information of the available tools in the literature, in hope of benefiting researchers with different academic backgrounds. In this paper, 4 primary functions concerning simulation, fractional order difference filter, estimation and forecast are compared and evaluated respectively in the different software and informative comments are also provided for selection.

Commentary by Dr. Valentin Fuster
2017;():V009T07A028. doi:10.1115/DETC2017-67485.

Energy informatics (EI) is relatively a blossoming and dynamic research area especially in today’s green manufacturing world. Using renewable energy and clean technology are the keys to a revitalization of the world manufacturing and job creation. Green manufacturing, which reduces resource use, waste and emissions and saving the energy, has become the priority for the manufacturers. Therefore, EI has come into a desirable solution. The fractional calculus (FC) is a mighty tool which can characterize the complex properties of the natural and social phenomena. In this paper, we have provided an overview on the current EI by describing current research topics and methods and then pointed out an outlook of how this new field might be evolved with FC in the coming future.

Commentary by Dr. Valentin Fuster
2017;():V009T07A029. doi:10.1115/DETC2017-67634.

Many processes in the industry can be modeled as fractional order, research on the fractional order become more and more popular. Usually, controllers such as fractional order PID (FOPID) or fractional active disturbance rejection control (FADRC) are used to control single-input-single-output (SISO) fractional order system. However, when it comes to fractional order two-input-two-output (TITO) processes, few research focus on this. In this paper, a new design method for fractional order control based on multivariable non-internal model control with inverted decoupling is proposed to handle non-integer order two-input-two-output system. The controller proposed in this paper just has two parameters to tune compared with the five parameters of the FOPID controller, and the controller structure can be achieved by internal model control (IMC) method which means it is easy to implement. The parameters tuning method used in this paper is based on frequency domain strategy. Compared with integer order situation, fractional order method is more complex, because the calculation of the frequency domain characteristics is difficult. The controller proposed in this paper is robust to process gain variations, what’s more, it provides ideal performance for both set point-tracking and disturbance rejection. Numerical results are given to show the performance of the proposed controller.

Commentary by Dr. Valentin Fuster
2017;():V009T07A030. doi:10.1115/DETC2017-67685.

This paper investigates the controllability of distributed-order fractional systems with distributed delays. By using the controllability Gramian matrix and reduction to absurdity, a necessary and sufficient condition for the controllability of linear system is established, and a sufficient condition for the nonlinear system is obtained. Examples are given to illustrate the effectiveness of the theorems.

Topics: Delays
Commentary by Dr. Valentin Fuster
2017;():V009T07A031. doi:10.1115/DETC2017-67692.

This paper is concerned with the investigation of the regional controllability of the fractional order differential inclusion (FODI). First, some preliminaries and definitions of regional controllability of the system are introduced. Then we obtained some equivalent conditions of regional controllable from the viewpoint of set relations and analyzed the regional controllability with minimum energy of a class of time fractional order differential inclusion.

Topics: Optimal control
Commentary by Dr. Valentin Fuster
2017;():V009T07A032. doi:10.1115/DETC2017-67903.

Existence of periodic solutions of fractional order dynamic systems is an important and difficult issue in fractional order systems field. In this paper, the non existence of completely periodic solutions and existence of partly periodic solutions of fractional order linear time varying periodic systems and fractional order nonlinear time varying periodic systems are discussed. A new property of Laplace transform of periodic function is derived. The non existences of completely periodic solutions of fractional order linear time varying periodic systems and fractional order nonlinear time varying periodic fractional order systems are presented by Laplace transform method and contradiction approach. The existence of partly periodic solutions of fractional order dynamic systems are proved by constructing numerical examples and considering Laplace transform property approaches. The examples and state figures are given to illustrate the effectiveness of conclusion presented.

Commentary by Dr. Valentin Fuster
2017;():V009T07A033. doi:10.1115/DETC2017-68270.

In this paper, stability of fractional order (FO) systems is investigated in the sense of the Lyapunov stability theory. A new definition for exponential stability of the fractional order systems is given and sufficient conditions are obtained for the exponential stability of the FO systems using the notion of Lyapunov stability. Besides, a less conservative sufficient condition is derived for asymptotical stability of FO systems. The stability analysis is done in the time domain. Numerical examples are given to show that the obtained conditions are effective and applicable in practice.

Commentary by Dr. Valentin Fuster

13th ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Mechatronic Control and Electrical Vehicular Systems

2017;():V009T07A034. doi:10.1115/DETC2017-67390.

Real-Time simulation and Hardware-in-the-Loop (HIL) testing are increasingly adopted by industry for the development and validation of complex systems. This paper presents the real-time modeling and power management of a Vehicle-Grid Integration (VGI) system. The VGI system consists of six AC level 2 Plug-in Electric Vehicle (PEV) charging stations, a Photovoltaics (PV) farm, a commercial building load, and a switch connecting to 240V single phase power grid. PEV charging activities follow the SAE J1772 standard. An energy management algorithm is designed for the VGI system to coordinate the PEV charging with the building load and PV renewable generation. The coordination maintains the power consumption of the VGI system below utility’s demand charge pricing threshold. A real-time power system simulator, Opal-RT, is used in this study. The OPAL-RT system allows users to build detailed power system models using Matlab Simulink/SimPowerSystems and RT-LAB library, and run the models in real-time. The model-based approach enables the integration of power system models seamlessly with the power management algorithm and power electronics-level controllers. The simulation results show that the VGI model emulates the real system well and the coordinated PEV charging helps to balance the power generation and consumption of the VGI system to meet power management requirement.

Commentary by Dr. Valentin Fuster
2017;():V009T07A035. doi:10.1115/DETC2017-67939.

In terms of the electric vehicles is an important issue of sizing a battery pack. The designer must take account of parameters such as cost, weight and durability. We can optimize these parameters with the help of a battery management system with integrated active cell balancing function. The article describes the development of a battery management system that developed by the Research Centre of Vehicle Industry at Széchenyi István University, Győr, Hungary.

Commentary by Dr. Valentin Fuster
2017;():V009T07A036. doi:10.1115/DETC2017-67978.

The current paper presents a realization of a complex vehicle control task. The goal was to consume the lowest possible energy in a less than 100 kg, wheel hub motor-driven vehicle. The realization is based on two distinguishable operating states which states characterizes well the driving cycle of the vehicle. The main contribution of the proposed method is that it reliably estimates the external loads which interacts the vehicle, the controller can adapt to this changes thus it can guarantee the minimal energy consumption. The vehicle described in the paper is a participant at the Shell Eco-marathon Europe competition in Urban Concept - Battery Electric category.

Commentary by Dr. Valentin Fuster

13th ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Mechatronics and Embedded Systems Applications

2017;():V009T07A037. doi:10.1115/DETC2017-67356.

Authenticating persons using fingerprints is a widely accepted method in the field of access control, border control, prosecution and many others. Today, fingerprint modules with customizable firmware can be bought commercially off the shelf by hobbyists and small companies to be used in their applications and are usually locally separated from a controller implementing the feature extraction and comparison algorithms. As a matter of fact, the communication channel between the sensor and the controller module is susceptible to eavesdropping and man in the middle attacks. Nevertheless, adding communication channel security to such a system has a direct negative impact on the system’s response time, thus directly affecting user acceptance. The aim of this paper is to provide a comprehensive investigation on measures to counter run-time degredation when adding communication channel security on behalf of an existing fingerprint verification chain. We show that a combination of the elliptic curve Diffie-Hellman key exchange together with AES-256 and the use of parallelization using OpenMP on a controller node leads to an acceptable run time making key creation and exchange upon every fingerprint read request a suitable undertaking.

Commentary by Dr. Valentin Fuster
2017;():V009T07A038. doi:10.1115/DETC2017-67742.

Manual work is a cornerstone of manufacturing, also for factories of Industry 4.0 era. Use cases of manual work regard the production of single item, customized assemblies, small batches. Several injuries can be caused or aggravated by manual handling activities at work. Moreover, the efficiency of the whole process can benefit from correct body posture, parts’ visibility and accessibility. Finally, manual work is strongly human-centered and its performance is affected by the expertise, the level of knowledge, attitudes and belief of workers.

In this complex context where multiple factors such as Efficiency, Work Performance, Ergonomics and Safety relate each other to achieve a satisfactory smart industry, the paper proposes an innovative Tangible Augmented Reality platform to train and assist workers during the manual handling and assembly tasks necessary to produce consumer goods with high aesthetic qualities. The proposed platform is the result of the application of a multipath methodology to link health and safety elements, typologies of injuries, ergonomics factors and relative qualitative and quantitative assessment methods and ergonomics analysis tools. The TAR platform allows the worker to consult the assembly instructions in a simple and user friendly way and to be informed by potential risk of injuries by a real-time alert. Based on video mapping techniques, the TAR system superimposes the necessary digital contents on the physical model of the product while the operator is building it.

Topics: Manufacturing
Commentary by Dr. Valentin Fuster
2017;():V009T07A039. doi:10.1115/DETC2017-68184.

Being able to correctly assess the context it is currently acting in is a very important ability for every autonomous robot performing a task in a real world scenario such as navigating, manipulating an object or interacting with a user. Sensors are the primary interface with the external world and the means through which contextual knowledge is generated. Humans and animals use cognitive processes such as attention to selectively process perceived task-relevant information and to recognize the context they are currently acting in. Biologically inspired computational models of attention have been developed in recent years to be used as interpretation keys of mainly visual sensor data. This paper presents a new framework for situation assessment that expands existing computational models of attention by providing a unified methodology to interpret and combine data from different sources. The method utilizes probabilistic state estimation techniques such as Bayesian recursive estimation, Kalman filter, and hidden Markov models to interpret features extracted from sensor data and formulate hypotheses about different aspects of the task the robot is performing or of the environment it is currently acting in. The concept of Bayesian surprise is also used to mark the information content of each new hypothesis. A weight that takes into account the confidence in the estimate that generated the hypothesis, its information content, and the quality of the data is then calculated. The methodology presented in this paper is general and allows to consistently apply the framework to data from different types of sensors and to then combine their hypotheses. Once formulated, hypotheses can then be used for context-based reasoning and plan adaptation. The framework was implemented on a small two-wheel differential drive robot equipped with a camera, an ultrasonic and two infrared range sensors. Three different sets of results that evaluate the performance of different features of the framework are presented. First, the method has been applied to detect a target object and to distinguish it from similar objects. Second, the hypotheses strength calculation method has been characterized by isolating the effect of belief, surprise, and of the quality of the data. Third, the combination of hypotheses from different modules has been evaluated in the context of environment classification.

Topics: Robots
Commentary by Dr. Valentin Fuster
2017;():V009T07A040. doi:10.1115/DETC2017-68311.

Refreshable Braille Display (RBD) is a device that enables people with blindness to access digital textual content through tactile interface. The use of commercially available RBDs is restricted to affluent individuals and organizations due to their high cost, which restricts their penetration in developing nations. Braille displays based on shape memory alloy actuators are a potential low cost alternative but face the challenge of high power consumption, heat accumulation and low response time. This paper proposes an SMA based actuator with a novel latching mechanism to make RBDs. It also discusses the design and production challenges addressed in making the RBD. It further compares the performance of the current prototypes with previous designs of SMA based RBDs.

Commentary by Dr. Valentin Fuster
2017;():V009T07A041. doi:10.1115/DETC2017-68362.

In this article, C-STEM Studio, a platform for hands-on integrated learning of Computing, Science, Technology, Engineering and Mathematics (STEM) with robotics, is presented. C-STEM Studio integrates many technologies, software, and curriculum that K-12 educators can use in their classroom. Ch, a C/C++ interpreter, provides an environment for computing. Linkbot Labs, Ch Linkbot Controller, and Ch Robot Controller allow teachers to utilize the robotics, such as Linkbots and Lego Mindstorms NXT and EV3, to help teach concepts in mathematics and science. RoboSim and RoboBlockly are simulation environments that allow students without physical robots to learn with virtual robots. Teachers can also teach embedded systems with Ch Arduino package, designed atop Ch. Also, easy-to-use resources explorers are built in the C-STEM Studio so that teachers and students can access teaching resources, students homework and materials come with those software. Finally, we provided a solution for Chromebook users to run C-STEM Studio through Raspberry Pi.

Commentary by Dr. Valentin Fuster

13th ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Mechatronics and Industry 4.0

2017;():V009T07A042. doi:10.1115/DETC2017-67315.

In this paper we present a configurable object recognition and locating system for 3D point cloud sensors. The objects are recognized based on cylindrical projection histograms and after the object is recognized, the initial pose of the object is computed based on the eigenvectors of the modelled and measured 3D point clusters. The optimal 6 degree of freedom pose is estimated by fitting the CAD-model surfaces to the measured 3D-points, where the model surfaces and 3D points are correlated based on the modelled and measured eigenvectors. The novelty of our system is the combination of reliable histogram based object recognition and accurate CAD-based pose estimation in the object recognition system with configurability options according to application requirements and point cloud properties.

Commentary by Dr. Valentin Fuster
2017;():V009T07A043. doi:10.1115/DETC2017-67708.

Dexterous gripper requirements, such as in-hand manipulation is a capability on which human hands are unique at; numerous number of sensors, degree of freedom, adaptability to deal with plurality of object of our hand motivate the researchers to replicate these abilities in robotic grippers. Developments of gripper or grasping devices have been addressed from many perspectives: the use of materials in the gripper synthesis, such as rigid or flexible, the approach of control, use of under-actuated mechanism and so on. Mathematical formulation of grasp modeling, manipulation are also addressed; however, due to the presence non-holonomic motion, it is difficult to replicate the behaviors (achieved in model) in a physical gripper. Also, achieving skills similar to human hand urge to use soft or non rigid material in the gripper design, which is contrary to speed and precision requirements in an industrial gripper. In this dilemma, this paper addresses the problem by developing modular finger approach. The modular finger is built by two well known mechanisms, and exploiting such modular finger in different numbers in a gripper arrangement can solve many rising issues of manipulation.

Topics: Grippers
Commentary by Dr. Valentin Fuster
2017;():V009T07A044. doi:10.1115/DETC2017-67797.

The paper reports on a use case of vertical integration and predictive maintenance, two concepts that fall within the wider “Industry 4.0” domain. We designed an Internet of Things based-system for the collection, processing and management of data coming from central vacuum cleaners. The developed embedded system for data retrieval from the vacuum via MODBUS and for sending them to a cloud server via WiFi is described in detail. We also present the software techniques used to manage data and the application developed for the presentation of collected data to several types of users: administrators, customers and distributors. Finally, they are highlighted the advantages for using information stored in optimizing the assistance service, marketing opportunities and market analysis.

Topics: Vacuum
Commentary by Dr. Valentin Fuster

13th ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Micro-/Nano-Manipulation Technologies and Applications

2017;():V009T07A045. doi:10.1115/DETC2017-67621.

This paper is concerned with the ultra high precision tracking control problem of a class of hysteretic systems with both external disturbances and model uncertainties. By integrating a time rate function of the input into the classical Prandtl-Ishlinskii operators, a rate-dependent Prandtl-Ishlinskii model is introduced to compensate the rate-dependent hysteresis of such systems. Furthermore, the resulting inverse compensation error is considered, and a finite-time convergent disturbance observer-based sliding mode control methodology is proposed to improve both the tracking accuracy and transient performance. In this control methodology, a finite-time convergent disturbance observer is employed to estimate various disturbances for accurate eliminations, where the inverse compensation error is regarded as a bounded disturbance. Meanwhile, a novel sliding mode controller is designed to achieve the finite-time stability of the closed-loop system. In particular, it can be proved that both the sliding variable and disturbance estimated error can converge to zero in a finite time. Finally, the proposed control architecture is applied to a PZT (piezoelectric transducer) actuated servo stage, where good hysteresis suppression capability and excellent tracking performance are demonstrated in the experimental results.

Commentary by Dr. Valentin Fuster
2017;():V009T07A046. doi:10.1115/DETC2017-68043.

This paper presents an innovative large stroke XY compliant nanopositioner with a self-adjusting stiffness center (SASC) module in order to minimize the in-plane parasitic rotation. Double parallelogram flexure is utilized to achieve kinematics decoupling. Moreover to realize SASC, an additional planar joint based on parallelogram flexure is adopted, which significantly reduces the in-plane moment. SASC design approach makes the stiffness center adjust by itself and stay fixed by the variation of the stiffness of parallelogram flexures when the stage is in motion. In a case study, a 1mm × 1 mm XY nanopositioner with a SASC module is presented in details. Finite element analysis (FEA) results show that the proposed XY positioner is capable to achieve the required millimeters stroke, and significantly reduces parasitic rotation with the SASC design.

Topics: Stiffness
Commentary by Dr. Valentin Fuster
2017;():V009T07A047. doi:10.1115/DETC2017-68053.

It is well believed that S-curve motion profiles are able to reduce residual vibration, and are widely applied in the motion control fields. Recently, a new asymmetric S-curve (AS-curve) motion profile, which is able to effectively adjust the acceleration and deceleration periods, is proposed to enhance the performance of S-curve motion profile, and proved to be better than the traditional symmetric S-curve in many cases. However, most commercial motion controllers do not support the AS-curve motion profiles inherently. Special knowledge or expensive advanced controlling systems, such as dSPACE system, are required to generate the AS-curve motion command, which limits the applications of the AS-curve motion profile in many practical applications. In this paper, a generic method based on the Position-Velocity-Time (PVT) mode move supported by most commercial motion controllers is proposed to generate exact AS-curve motion command in real machines. The analytic polynomial functions of AS-curve motion profile are also derived to simplify the further application, and the effectiveness of the proposed method is verified by numerical simulation.

Commentary by Dr. Valentin Fuster
2017;():V009T07A048. doi:10.1115/DETC2017-68066.

The flexure-hinge (FH) based guiding mechanism, such as fast tool servo (FTS) or micro-lens-array punching machine, is widely used in micro/nano precision engineering, due to their good linearity of stiffness. The major design advantage of FHs for this application was the absence of backlash and friction in the direction of the motion. This provides very smooth, high-precision operating characteristics without inducing evident wear which is commonly associated with high speeds or continuous operation. The dynamic model of FH can be simplified as a spring-mass-damping system, both the stiffness and frequency of a mechanism play significant roles in its dynamic performance. However, the relationship between dynamic response and the input function is nonlinear. In order to achieve precision displacement output under different excitation frequency, nonlinear input compensation should be considered. In this paper, an innovative method is provided to handle this kind of problem, where the stiffness of the guiding mechanism can be adjusted, such that the output amplitude scale can be remained the same at any excitation frequency, therefore, it become a linear system, the input is very easy to control. The tension stiffening is used to change the stiffness and thus the frequency, and the relationship between the change rate of frequency and tension force is also revealed. Finally, the control strategy is given, and an example is given to show the efficient of the presented method.

Commentary by Dr. Valentin Fuster

13th ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Robotics and Mobile Machines (RMM)

2017;():V009T07A049. doi:10.1115/DETC2017-67385.

STRIDER: Semi-Autonomous Tracking Robot with Instrumentation for Data-Acquisition and Environmental Research, a semi-autonomous aquatic vessel, was envisioned for automated water sampling, data collection, and depth profiling to document water quality variables related to agricultural run-offs. Phase-I of the STRIDER project included the capability for STRIDER to collect water samples and water quality data on the surface of water bodies. This paper discusses the Phase-II efforts of the project, in which the previous design of STRIDER was adapted to extend its capabilities to include monitoring, depth profiling, and visualization of in-situ water quality data at various depths as well as collect water samples at each depth for bacterial analysis. At present, the vessel has been utilized for navigation to specified locations using remote control for collecting water quality data and water samples from the surface, as well as 2 feet and 4 feet below the surface at multiple UMES ponds. In a series of preliminary trial runs with the supervision of UMES faculty members and collaborators from the United States Department of Agriculture (USDA), STRIDER successfully collected 48 water samples for bacterial analysis at different locations and depths of ponds on the UMES campus. Design alternatives are being explored for more efficient water sampling capabilities.

Commentary by Dr. Valentin Fuster
2017;():V009T07A050. doi:10.1115/DETC2017-67540.

This paper presents the functional design and dynamics optimization of a reconfigurable 3-DoF parallel kinematics manipulator conceived for motions of pure rotations and pure translations. The main peculiarity of the device, indeed, is that of allowing changes of the mobility of its moving platform. The kinematic structure of the three identical legs is designed in a way that, when a particular configuration of the manipulator is reached, the transition between the working modes is possible through the reconfiguration of three metamorphic universal joints, which are used to connect each limb to the ground. This configuration allows to limit the weight of the moving bodies of the robot, with a consequent enhancement of the dynamic performance. The kinematics of the parallel robot is introduced in the very first part of the work as a necessary preamble to the optimization of the manipulator geometry, which has been performed in two steps: at first, the Jacobian matrices which characterize the two working modes were used as performance indices for the preliminary functional optimization of the device; subsequently, an optimization of the dynamic behaviour was performed to obtain a complete characterization of the robot in both its modes.

Topics: Robots , Design , Optimization
Commentary by Dr. Valentin Fuster
2017;():V009T07A051. doi:10.1115/DETC2017-68049.

The paper presents a new formal way of modeling and designing reconfigurable robots, in which case the robots are allowed to reconfigure not only structurally but also functionally. We call such kind of robots “self-evolvable”, which have the potential to be more flexible to be used in a wider range of tasks, in a wider range of environments, and with a wider range of users. To accommodate such a concept, i.e., allowing a self-evovable robot to be configured and reconfigured, we present a series of formal constructs, e.g., structural reconfigurable grammar and functional reconfigurable grammar. Furthermore, we present a correct-by-construction strategy, which, given the description of a workspace, the formula specifying a task, and a set of available modules, is capable of constructing during the design phase a robot that is guaranteed to perform the task satisfactorily. We use a planar multi-link manipulator as an example throughout the paper to demonstrate the proposed modeling and designing procedures.

Topics: Robots , Construction
Commentary by Dr. Valentin Fuster
2017;():V009T07A052. doi:10.1115/DETC2017-68095.

Manufacturers answered to the global competition rise by increasing the efficiency of their development process by substituing the hardware tests with their virtual counterpart. Following the same idea, in this paper, the introduction of the virtual prototyping technique in the design of a complex robotic leg is proposed. The novelty of this work is double: the first motivation lies on the characteristic of the mechanism, since it is a FLEXible jumping LEG; the second one, instead, regards to the introduction of methods well known in other research field but rarely used in robotics. This paper describes the whole design process, while the assembly of the physical prototype, the control development and the experimental tests will be matters of future works.

Topics: Robotics
Commentary by Dr. Valentin Fuster

13th ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Sensors and Actuators

2017;():V009T07A053. doi:10.1115/DETC2017-67628.

In this paper, real-time feedfoward position control algorithm of electro-hydraulic actuator (EHA) is proposed. To reduce nonlinearity of EHA, model uncertainty and disturbance, feedback system with proportional-integral-derivative (PID) controller is used. The feedback system is estimated as linear dirsrete time transfer function by recursive least squares algorithm. Feed-forward controller using inverse model generates filtered signals that compensate magnitude and phase of feedback system. For high bandwidth control, fast sample rate is necessary and it causes NMP zeros of estimated transfer function. The NMP transfer function is inversed by zero phase error tracking control (ZPETC) method and the inverse model is used to feedforward controller. The real-time experiment is conducted by NI-CompactRio and Labview, and the simulation is programmed in MATLAB/Simulink. The results of simulation verify the validity of proposed control strategy.

Commentary by Dr. Valentin Fuster
2017;():V009T07A054. doi:10.1115/DETC2017-67642.

Strain gauges based on the micro-strip patch antenna have been increasingly employed in structural health monitoring. However, the lower bandwidth, influenced by the antenna’s geometric properties, limits efficiency of the antenna when major strain, creating drastic variation of the resonant frequency, is applied. The performance of the antenna cannot be guaranteed without also considering the substrate’s varying thickness, caused by manual fabrication and printing procedure. However, all such considerations lead to an increase of multivariate design variables, that in turn, increase uncertainty and computational costs. Thus, the proposed research develops a framework that accurately models the geometric variables of the antenna and efficiently reduces the multivariate dimensions that draw uncertainty preventing accurate system reliability estimation. In the proposed framework, a dimension reduction method is thoroughly conducted by utilizing a critical decision criterion depending on the degree of correlation. Specifically, artificial neural network and probabilistic neural network are employed to correctly estimate the variability of complex system responses. Furthermore, an optimal design of the stretchable patch antenna is developed. This design will allow frequency shifts under tensile strain and still remain within reliable frequency ranges. The proposed approach is beneficial to the process of capturing and managing antenna design variables. The presented example clearly demonstrates the advantage of the obtained optimal design of the stretchable patch antenna compared to an ultra-wideband radar system that often requires complicated design processes and high computational costs.

Topics: Design , Electronics
Commentary by Dr. Valentin Fuster
2017;():V009T07A055. doi:10.1115/DETC2017-67874.

In this paper, we propose a new tunable pressure sensor based on the nonlinear snap-through instability of an electrically actuated shallow arch microbeam. The general concept of the sensor can be explained as follows: the shallow arch is excited to trigger dynamic snap-through instability yielding a high output amplitude, if the system operating pressure is below a threshold value. This state is interpreted as a digital logic 1. Once the varying pressure exceeds that threshold value, the arch gains its stability. Therefore, the new state would be interpreted as a digital logic 0 value. We show an example of an operation range of the proposed sensor by identifying the relationship between the excitation AC voltage and the critical cut-off pressure.

Commentary by Dr. Valentin Fuster
2017;():V009T07A056. doi:10.1115/DETC2017-68368.

In this paper, we provide a new voice recognition framework which allows K-12 students to write programs to solve problems using voice control. The framework contains the voice recognition module SPHINX which is based on an open source machine learning tool developed by Carnegie Mellon University and a wrapper function which is written in C/C++ interpreter Ch. The wrapper function allows students to interact the module in Ch. Along with Ch programming and robotic coursework, students will get the chance to learn the basic concept of machine learning and voice recognition technique. In order to bring students attention and interest in machine learning, various tasks have been designed for students to accomplish based on the framework. The framework is also flexible for them to explore other interesting projects.

Topics: Robotics , Education
Commentary by Dr. Valentin Fuster

13th ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Small Unmanned Aerial Vehicle Technologies and Applications (SUAVTA)

2017;():V009T07A057. doi:10.1115/DETC2017-67637.

In this paper, a distributed adaptive fault-tolerant cooperative control (FTCC) scheme is developed for flying multiple unmanned aerial vehicles (UAVs) with consideration of actuator and sensor faults. The communication network is an undirected, fixed topology and only a subset of UAVs has access to the common reference. By using a sliding-mode observer, the common reference is estimated by each UAV. The lumped uncertainties including external disturbances, actuator and sensor faults are estimated by an adaptive mechanism. On the basis of the estimated reference and lumped uncertainties, dynamic surface control technique is utilized to eliminate the computational burden inherent in the traditional backstepping control architecture. The highlight is that external disturbances, actuator and sensor faults are considered in the distributed control scheme for multi-UAVs simultaneously. By using graph theory and Lyapunov-based method, it is proved that all signals in the closed-loop system are bounded. Furthermore, simulation results are exhibited to demonstrate the effectiveness of the proposed control scheme.

Commentary by Dr. Valentin Fuster
2017;():V009T07A058. doi:10.1115/DETC2017-68246.

Optimization of water use relies on accurate measurement of water status of crops. Stem water potential (SWP) has become one of the most popular methods to monitor the water status of almond trees. However, it needs to take twice visit and at least thirty minutes to obtain one measurement, which makes it very difficult to understand the water status information in the orchard level. Unmanned aerial vehicle (UAV) based remote sensing promises to deliver reliable and precise field-scale information more efficiently by providing multispectral higher-resolution images with much lower cost and higher flexibility. This paper aims to extract almond water status from UAV-based multispectral images via building the correlation between SWP and vegetation indices. Different from the traditional method that focuses on normalized difference vegetation index (NDVI) means, higher-order moments of non-normalized canopy distribution descriptors were discussed to model SWP measurements. Results showed that the proposed methods performed better than traditional NDVI mean.

Commentary by Dr. Valentin Fuster

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