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ASME/IEEE 2009 International Conference on Mechatronic and Embedded Systems and Applications

2009;():3-8. doi:10.1115/DETC2009-86326.

This paper contributes on designing robotic self-optimizing memory controller for non-Markovian reinforcement tasks. Rather than holistic search for the whole memory contents the model adopts associated feature analysis to successively memorize a newly event state-action pair as an action of past experience. Actor-Critic learning is used to adaptively tuning the control parameters, while on-line variant of random forests (RF) learner is used as memory-capable to approximate the policy of Actor and the value function of Critic. Learning capability of the proposed model is experimentally examined through non-markovian cart-pole balancing task. The result shows that our self-optimizing memory controller acquired complex behaviors such as balancing two poles simultaneously, displays long-term planning and generalization capacity based on past experiences.

Commentary by Dr. Valentin Fuster
2009;():9-15. doi:10.1115/DETC2009-86688.

Multi-agent reinforcement learning is a challenging research topic used in various fields including robotics, artificial intelligence, distributed control, and so on. Recently, there have been lots of efforts to develop multi-agent reinforcement learning theories; but there exist many difficulties in multi-agent reinforcement learning system. In this paper, we introduce our on-going project BRIDS (Bio-insect and artificial Robot Interaction based on Distributed System), which is for interactions between a bio-insect and artificial robots using multi-agent reinforcement learning. The main objective of this project is to drive the bio-insect to the desired position using a group of artificial intelligent robots. Simulation results show that artificial intelligent robots drive the bio-insect to the target position using reinforcement learning.

Topics: Robots
Commentary by Dr. Valentin Fuster
2009;():17-25. doi:10.1115/DETC2009-86689.

In this paper, we address our on-going research that is for interaction between artificial robots and a bio-insect. The research motivation and research goal were introduced in [1]. In order to report a progress of this project, this paper contains advanced framework and simulation results. When we did experiments using real bio-insects, their movement showed a little randomness. For this reason, fuzzy logic is employed to drive the model-free bio-insect towards a desired point. The framework formulated in this paper is based on fuzzy reward system and fuzzy expertise measurement system. Fuzzy reward system uses three inputs and an output resulting in numerical value within −1 to 1. Fuzzy expertise measurement system is inspired by area of expertise. In area of expertise method, it uses expertise measurement equation for finding expert agent. Based on area of expertise method, our method uses three expertise measurements to calculate score of individual agent. Based on this score, agents can share their intelligences with weighted scores. Simulation results demonstrate the validity of the framework established in this research.

Topics: Robots
Commentary by Dr. Valentin Fuster
2009;():27-30. doi:10.1115/DETC2009-86986.

Magnetic sensing is a reliable technology that has been developed for the purposed of position measurement and guidance, especially for applications in autonomous robotic vehicles. To calculate a position of a magnetic guidance road, it should be estimated in real-time. While the capability of a microprocessor and memory spaces have the limitation in implementation. To solve the above problems, this paper proposes a new structure of the magnetic sensors included a vertical magnetic field. The proposed method uses the linear region of the sensor output, and position determination using a simple equation with a microcontroller. The position sensing technique was implemented in the guidance of autonomous vehicle. The test results show that position sensing can be useful for an autonomous robotic vehicle.

Commentary by Dr. Valentin Fuster
2009;():31-36. doi:10.1115/DETC2009-87251.

Line spectra in the radiated noise of marine vessels are the most visible signs, which can be detected, tracked and identified by enemy’s passive sonar. Insertion of resilient isolators between the machinery and the base is one of the most common methods for controlling unwanted vibration of the hull of submarine. Isolators in service are usually assumed to be linear and almost all the vibration isolation-n systems (VIS) are designed with linear theory, which satisfies engineering requirements in most situations. However, the nonlinear dynamical characteristics of VIS have attracted increasing attention in recent years due to the facts that onboard machinery trends towards more powerful and lighter, and that the demands in engineering for reducing vibration become more rigorous. Furthermore, some distinguishing features of nonlinear systems can be applied to achieve some special functions, among which the most important one is using chaos to reduce line spectra in the radiated noise of submarines based on the fact that response spectrum of a nonlinear system under harmonic excitation is a continuous one when chaos occurs. In this paper, a chaos synthesis method based on tracking control is prososed for a vibration isolation system (VIS) of on board machinery to make the chaotic motion in nonlinear VIS persistent. In this way, the line spectra in the radiated noise can be reduced effectively because the response spectrum of a chaotic system under harmonic excitations is a continuous and reduced one. Numerical simulations were carried out and the results showed that utilizing this method the nonlinear VIS not only possesses an excellent isolation performance of vibration and line spectra, but also reduces the amplitude of the isolated equipment notably.

Commentary by Dr. Valentin Fuster
2009;():37-43. doi:10.1115/DETC2009-87715.

This paper investigates multi-robot coordination for the deployment of autonomous mobile robots in order to carry out a specific task. A key to utilizing of the full potential of cooperative multi-robot systems is effective and efficient multi-robot coordination. The paper presents a novel method of multi-robot coordination based on an Artificial Immune System. The developed approach relies on Jern’s Immune Network Theory, which concerns how an antibody stimulates or suppresses another antibody and recognizes non-self antigens. In the present work, the robots are analogous to antibodies and the robotic task is analogous to an antigen in a biological immune system. Furthermore, stimulation and suppression in an immune system correspond to communication among robots. The artificial immune system will select the appropriate number of antibodies autonomously to eliminate the antigens. The developed method of multirobot coordination is verified by computer simulation.

Topics: Robots
Commentary by Dr. Valentin Fuster
2009;():45-52. doi:10.1115/DETC2009-87750.

Parallel computing is widely adotped in scientific and engineering applications to enhance the efficiency. Moreover, there are increasing research interests focusing on utilizing distributed networked computers for parallel computing. The Message Passing Interface (MPI) standard was designed to support portability and platform independence of a developed parallel program. However, the procedure to start an MPI-based parallel computation among distributed computers lacks autonomicity and flexibility. This article presents an autonomic dynamic parallel computing framework that provides autonomicity and flexibility that are important and necessary to some parallel computing applications involving resource constrained and heterogeneous platforms. In this framework, an MPI parallel computing environment consisting of multiple computing entities is dynamically established through inter-agent communications using the IEEE Foundation for Intelligent Physical Agents (FIPA) compliant Agent Communication Language (ACL) messages. For each computing entity in the MPI parallel computing environment, a load-balanced MPI program C source code along with the MPI environment configuration statements are dynamically composed as a mobile agent code. A mobile agent wrapping the mobile agent code is created and sent to the computing entity where the mobile agent code is retrieved and interpretively executed. An example of autonomic parallel matrix multiplication is given to demonstrate the self-configuration and self-optimization properties of the presented framework.

Commentary by Dr. Valentin Fuster
2009;():53-59. doi:10.1115/DETC2009-86217.

A uniaxial cyclic stretch apparatus is designed and developed for tissue engineering research. The biostretch apparatus employs non-contact electromagnetic force to uniaxial stretch a rectangular Gelfoam® or RTV silicon scaffold. A reliable controller is implemented to independently control four stretch parameters: strength, frequency, pattern, and duration of the stretch time. The non-contact driving force and the specially designed mounting tray allow researchers to use standard Petri dishes and commercially available CO2 incubators to culture an engineered tissue patch with mechanical stimulus. The apparatus greatly simplifies the culture process over existing biostretch apparatuses. Further, unlike traditional uniaxial stretch apparatuses, which normally fix one side and stretch other side, the new biostretch apparatus can also apply uniaxial stretch from both ends simultaneously. Using the biostretch apparatus, the distribution of strain on the Gelfoam® and GE RTV 6166 silicon scaffold is quantitatively analyzed.

Commentary by Dr. Valentin Fuster
2009;():61-67. doi:10.1115/DETC2009-86425.

This paper presents design, hardware, software, and parameter optimization for a novel robotic automation system. RABiT is a Rapid Automated Biodosimetry Tool for high throughput radiological triage. The design considerations guiding the hardware and software architecture are presented with focus on methods of communication, ease of implementation, and need for real-time control versus soft time control cycles. The design and parameter determination for a non-contact PVC capillary laser cutting system is presented. A novel approach for lymphocyte concentration estimation based on computer vision is reported. Experimental evaluations of the system components validate the success of our prototype system in achieving a throughput of 6,000 samples in a period of 18 hours.

Topics: Design
Commentary by Dr. Valentin Fuster
2009;():69-76. doi:10.1115/DETC2009-87075.

The automated sensing scheme described in this paper has the potential to automatically capture, discriminate and classify transients in gait. The mechanical simplicity of the walking platform offers advantages over standard force plates. There is less restriction on dimensions offering the opportunity for multi-contact and multiple steps. This addresses the challenge of patient targeting and the evaluation of patients in a variety of ambulatory applications. In this work the sensitivity of the distributive tactile sensing method has been investigated experimentally. Using coupled time series data from a small number of sensors, gait patterns are compared with stored templates using a pattern recognition algorithm. By using a neural network these patterns were interpreted classifying normal and affected walking events with an accuracy of just under 90%. This system has potential in gait analysis and rehabilitation as a tool for early diagnosis in walking disorders, for determining response to therapy and for identifying changes between pre and post operative gait.

Commentary by Dr. Valentin Fuster
2009;():77-84. doi:10.1115/DETC2009-87186.

Inertial sensors are widely used for a variety of biomedical applications, such as human activity monitoring. We present a wireless biomedical monitoring network used for measuring footstep parameters and the heart rate of a person. The wireless biomedical monitoring network uses inertial sensors to record and monitor heart rate and consists of multiple monitoring nodes placed on a person, that communicate with a base node. The monitoring nodes placed on a person’s ankle measure the acceleration generated during a footstep. By analysing this data, we are able to determine the average footstep length and walking velocity to be 80cm and the average walking speed to be 1m/s which corresponds to results found by existing studies. A monitoring node placed on the right Carotid artery in the neck region was able to measure the vibrations generated by the movement of blood. Analysis of the acceleration signals generated by the pressure pulse showed that it was possible to determine the heart rate of the person. We found that a sitting person had a heart rate of 75 BPM, which was confirmed by an electrocardiogram device. Further areas of investigation involve improving the sensitivity of the monitoring node’s accelerometer sensor by using a diaphragm and also to measure a person’s blood pressure using inertial sensing.

Topics: Biometry , Sensors
Commentary by Dr. Valentin Fuster
2009;():85-87. doi:10.1115/DETC2009-87252.

It is commonly known that vibrations and acoustic oscillations can cause both negative and positive influence on living organisms. The most harmful effect is caused by the tone acoustic oscillations when the tone frequency coincides with the resonance frequency of the whole body or individual organs. Hence, it is possible to make a conclusion that there are prerequisites for creation acoustic method having harmful or even mortal effect on the Colorado beetle organism. The subjects of the experiment were 8 beetles with the mass of 100 – 200mg. The frequency of the oscillation effect was 500–2500Hz. Examinations of the beetle after 6 hours showed that the biological death did take place. The repeated examination of the beetles after 24 hours showed the biological death of all the beetles exposed to acoustic influence. Using the described experiment, the resonance frequency for the beetle’s body was determined. So, it is possible to eliminate the Colorado beetle by exposing to vibration and acoustic oscillation. It is necessary to know the data relating to the mass of a beetle and its stiffness. Also, a question about the frequency band of the exposure arises. The resonance frequency of the body as a viscoelastic system is determined. The authors carry out experiments and determinate the mass and the stiffness of the Colorado beetle body. On the basis of the data of the outer inspection the biological death is registered for the beetle of the mass 100mg after the influence of the 1500Hz frequency vibration noise level was 120dB. On the basis of these data the stiffness of the Colorado beetle body is estimated as 8,860 N/m.

Topics: Acoustics
Commentary by Dr. Valentin Fuster
2009;():89-97. doi:10.1115/DETC2009-87786.

The design of a new device called Tissue Resonator Indenter Device (TRID) for measuring soft tissue viscoelastic properties is presented. The two degrees-of-freedom device works based on mechanical vibration principles. When TRID comes into contact with a soft tissue, it can identify the tissue’s viscoelastic properties through the change of the device’s natural frequencies and damping ratios. In this paper, the deign of TRID is presented assuming Kelvin model for tissues. By working in the linear viscoelastic domain, TRID is designed to identify tissue properties in the range of 0–100 Hz. Assuming Kelvin model for tissues, the current paper develops a method for determining unknown tissue parameters using input-output data from TRID. Moreover, it is proved that the TRID’s parameters as well as the Kelvin tissue model parameters are globally identifiable. A parametric identification method using the prediction error approach is proposed for identifying the unknown tissue parameters in a grey-box state-space model. The reliability and effectiveness of the method for measuring soft tissue’s viscoelastic properties is demonstrated through simulation in the presence of considerable input and output noises.

Commentary by Dr. Valentin Fuster
2009;():99-108. doi:10.1115/DETC2009-87803.

A new wearable parallel robot has been designed and constructed for ankle joint rehabilitation treatments. The robot employs four pneumatic muscle actuators (PMA) together with cables to achieve three rotational degrees of freedom (dof) of its end platform. Parallel topology of the robot, unpredictable environment along with the time varying and non-linear behavior of actuators impose modeling and control challenges which are difficult to comprehend. In this paper an optimal fuzzy dynamic model of the pneumatic muscle has been developed to accurately predict the muscle behavior. The model is capable of mapping the complex relationship in length, force and pressure of the PMA with higher accuracy. This model has been further used to develop a fuzzy control scheme for the ankle robot. Experimental results are obtained to study and model the simultaneous actuation of all the actuators. Comparison with the previous dynamic modeling and control schemes demonstrates an improved performance of the proposed fuzzy controller.

Commentary by Dr. Valentin Fuster
2009;():109-118. doi:10.1115/DETC2009-87509.

The main objective for this research is to design an economical and robust swarm system to achieve formation control. The system combines swarm intelligence with centroidal Voronoi tessellations (CVT) to create desired static and dynamic formations. This paper also analyzes the affect of initial starting positions and robot number on formation performance. Experiments are conducted both in simulation and on an actual mobile robot platform which show the flexible and robust nature of CVTs over other formation control algorithms.

Commentary by Dr. Valentin Fuster
2009;():119-126. doi:10.1115/DETC2009-87613.

This paper describes a secure migration process of mobile agents between agencies. Mobile-C is an IEEE Foundation for Intelligent Physical Agents (FIPA) standard compliant multi-agent platform for supporting C/C++ mobile and stationary agents. This secure migration process is inspired from Secure Shell (SSH). Before migration, both agencies authenticate each other using public key authentication. After successful authentication, an encrypted mobile agent is transferred and its integrity is verified. Mobile-C is specially designed for mechatronic and factory automation systems where, for correct system operations, agencies must accept mobile agents from trusted agencies. For this reason, the emphasis is on strong authentication of both agencies involved in migration process. Security aspects of other popular mobile agent systems are described briefly. A comparison study with SSH protocol is performed and future work is elaborated.

Topics: Shells
Commentary by Dr. Valentin Fuster
2009;():127-134. doi:10.1115/DETC2009-87627.

Mission-based multi-robot systems (MRS) require the ability to quickly adapt to different missions while maintaining the innate advantages of cooperation and fault tolerance. This requires a flexible architecture capable of adapting to real-time changes in the system while dynamically assigning tasks to available drones. The provided mobile agent-based dynamic task allocation architecture enables non-centralized methods for allocating tasks to a heterogeneous system of mobile robots. The architecture utilizes three types of intelligent software agents including a mobile task agent, stationary control agent, and a mobile behavior agent. A mobile task agent is used to automatically collect the next available task and communicates with the on-board stationary control agent in order to complete the desired task. A mobile behavior agent is used to automatically gather the robot specific behaviors necessary to execute the low-level reactive control system required for the task. A case study involving border patrolling demonstrates the feasibility of the dynamic task allocation architecture. A simple yet effective wall-following behavior algorithm is given.

Commentary by Dr. Valentin Fuster
2009;():135-142. doi:10.1115/DETC2009-87822.

This paper proposes a system providing the operator with an intuitive method for controlling a micromanipulator during intracellular injection. A low-cost haptic device is utilised and 3D position-to-position kinematic mapping allows the operator to control the micropipette using a similar method to handheld needle insertion. The workspaces of the haptic device and micromanipulator are analysed and the importance of appropriate scaling to positioning resolution and tracking performance is investigated. The control issues integral to achieving adequate control of the micromanipulator using the Phantom Omni haptic device are addressed. Aside from offering an intuitive method for controlling the micropipette, this work lays the foundation for real-time haptic assistance in the cell injection task.

Topics: Haptics
Commentary by Dr. Valentin Fuster
2009;():143-149. doi:10.1115/DETC2009-87178.

This paper describes a control system for a tubular synchronous linear motor based on a combination of a linear PID controller and a nonlinear neural network. The nonlinear part of the controller is introduced to progressively augment the tracking performance of the system and is trained online by a compact GA. In particular, we implement a variant of a known compact GA that well lends itself to practical implementations in low capacity microcontrollers, thanks to its reduced memory requirements and better distributed computational loads. The potential of the proposed approach is assessed by means of experimental tests using a tubular linear synchronous motor prototype. The control system obtained through genetic search outperforms alternative schemes obtained with linear design techniques in terms of robustness to payload mass change and sensitivity to static friction.

Commentary by Dr. Valentin Fuster
2009;():151-158. doi:10.1115/DETC2009-87337.

A new strategy to realize an FPGA implementation of a soft sensor for an industrial process is proposed. The proposed approach is based on the integration on Field Programmable Gate Array (FPGA) of a neural networks. The proposed method has been applied to develop a soft sensor for the estimation of the freezing point of kerosene in an atmospheric distillation unit (topping) working in a refinery in Sicily, Italy.

Commentary by Dr. Valentin Fuster
2009;():159-163. doi:10.1115/DETC2009-87841.

In this paper an indoor aid to assist and to guide blind people exploring an unfamiliar structured environment is proposed. The system developed aims to lead the visual impaired to reach a specified destination suggesting him the path to walk avoiding obstacles and hazards and notifying the presence of services along the path. Main advantages of the system developed, as respect to the State of the Art, are the continuous monitoring of users position in the environment, the optimized redundancy of information to be provided to the user, the high reconfigurability, the poor demanding installation and the adaptive level of assistance to be provided to the user on the basis of his/her needs, ability and skills.

Commentary by Dr. Valentin Fuster
2009;():165-174. doi:10.1115/DETC2009-86108.

This paper presents the requirements of an automotive gateway for in-vehicle networks. Modern vehicles include several heterogeneous networks such as LIN, CAN, FlexRay, and MOST. The gateway enables seamless communication between heterogeneous networks. The role of a gateway is not complex, but the gateway has the potential to damage the operation of other connected electronic control units and networks. In this paper, we analyze the requirements for the automotive gateway from the viewpoint of hard real-time embedded systems in automotive distributed control systems. We implement the gateway based on these requirements. Finally, we evaluate the performance of the gateway.

Commentary by Dr. Valentin Fuster
2009;():175-184. doi:10.1115/DETC2009-86109.

We describe the software core of a generic system test framework, named TF, for engineering verification of embedded and mechatronic systems. TF originated as an automated system test framework for the Siemens FireFinder XLS fire-safety system, but can be easily customized to place other systems under test. As a scalable and safety-critical system under rigorous certification constraints, XLS placed some very stringent requirements on the test harness. We performed a thorough evaluation of the available options for test executives, selecting the best one for our purposes. We then built TF on that test executive. TF enables high levels of productivity for both test developers and framework maintainers. TF also allows simulators to be substituted for physical hardware, without modifying the test scripts or underlying infrastructure. This feature is vitally important in scalability testing.

Commentary by Dr. Valentin Fuster
2009;():185-192. doi:10.1115/DETC2009-87373.

Monte Carlo Localization (MCL) is a common method for self-localization of a mobile robot under the assumption that a map of the environment is available. In addition to laser scanners and sonar sensors, localization approaches using vision sensors have also been recently developed with good results. In this paper we present two variations to improve the standard implementation of the MCL algorithm. The first change consists in a new strategy for the generation of particles, both at the initialization and at the resampling stage, which tries to generate new particles near the position of images in the learning dataset or in the neighborhood of particles with higher weights in the previous estimate, respectively. The second variation is related to a new approach to the estimate of the robot position, now based on two steps: clustering of particles and taking as estimate of robot position the center of the cluster, computed as a weighted sum of particle weights, with higher weight. The improved MCL algorithm described in this paper is compared with the standard MCL algorithm in terms of localization accuracy. In particular, tests were performed using local feature matching of omnidirectional images implemented on a real robot system operating in large outdoor environments with high dynamic content. Obtained results show that the localization accuracy of the improved MCL algorithm is more than twice that of the standard MCL algorithm.

Commentary by Dr. Valentin Fuster
2009;():193-202. doi:10.1115/DETC2009-87769.

Utilizing non-zero offsets when scheduling real-time periodic processes significantly increases the chances of satisfying all the timing constraints in a real-time system. In this paper, a method that enables the utilization of non-zero offsets in the pre-run-time scheduling of asynchronous and periodic processes with release times, deadlines, precedence and exclusion relations on either a uniprocessor or on a multiprocessor in real-time embedded systems is presented. This paper also identifies for the first time, the set of general conditions that a periodic process newpi with release time rnewpi , computation time cnewpi , deadline dnewpi , period prdnewpi , permitted range of offset onewpi , must satisfy, in order to satisfy the timing constraints of any given asynchronous process ai with computation time cai , deadline dai , minimum time between two consecutive requests minai , and earliest time that asynchronous process ai can make a request for execution lai . A method based on these general conditions for converting asynchronous processes with earliest request times into new periodic processes with offset constraints is also introduced.

Commentary by Dr. Valentin Fuster
2009;():203-208. doi:10.1115/DETC2009-86651.

A bearing diagnosis system that combines cepstrum coefficient method for feature extraction from bearing vibration signals and artificial neural network (ANN) models for the classification is proposed in this paper. We first segment the vibration signal and obtain the corresponding cepstrum coefficients, then classify the motor systems through ANN models. Utilizing the proposed method, one can identify the characteristics hiding inside the vibration signal and then diagnose the abnormalities. To evaluate this method, several experiments for the normal and abnormal conditions have been performed in the laboratory and the results are used to verify the method. It is shown that the proposed method had effectively distinguished the difference between the normal and abnormal cases and classified correctly the corresponding feature conditions.

Commentary by Dr. Valentin Fuster
2009;():209-214. doi:10.1115/DETC2009-86837.

An iterative learning control strategy based on the expert knowledge is proposed in the slide position control of the mechanical press. The slide can be stopped on an accurate position at any point of the slide travel. The proposed strategy is more efficiency and accurate than the original inching operation method. A new computer control system is developed for the mechanical press. Experimental results are shown that the proposed control strategy on the press JH23-63 is effective.

Topics: Power presses
Commentary by Dr. Valentin Fuster
2009;():215-222. doi:10.1115/DETC2009-87326.

This paper discusses the suitability of a special discrete filter, called balancing filter, to improve the performance of model-based fault detection and fault diagnosis on a centrifugal pump in active magnetic bearings. The focus in this subject lies on the extraction of better symptoms for the fault diagnosis. The application of the balancing filter sets up on a multi-model approach which uses a model of the system for the reference state and every fault that is to be detected. These models are stimulated with the same test signals as the ones applied to the process while it is running. To compare the simulation results of the models with the process response the output error is calculated. After this the remaining residuals are used as symptoms for the fault detection. The balancing filter is used to remove the large differences within the amplitude responses of the models caused by the lowpass characteristics of the mechanical part of the system. Hence the influence of the smaller differences caused by the examined faults is weighted equally at all interesting frequencies. This leads to new residuals which are separated more clearly. This approach is used to detect common faults appearing on centrifugal pumps as dry run, incorrect installation and worn out balance pistons. The test rig used to examine the suitability of the proposed filter is a one-level centrifugal pump in magnetic bearings. The rotor of the pump is driven by an asynchronous motor at rotation speeds up to 3000 rpm . The first flexible mode of the rotor is located at 280 Hz . In the seal gap fluid-structure-interaction is appearing. The forces on the rotor are calculated based on the current applied to the bearings, while its displacement is measured by eddy current sensors integrated into the bearings. The first two natural frequencies of the system are located at about 200Hz and 500 Hz . These frequencies are shifted when a fault is occuring. In the models for the fault states this behaviour is represented. Hence the model matching the current state of the pump leads to the lowest residual. The advantage of the balancing filter is that the detection of faults becomes more reliable. Below the examined faults, the model-based concept and the design of the balancing filter are described in detail. Results from experiments on the test rig are given to show the advantages of the balancing filter.

Commentary by Dr. Valentin Fuster
2009;():223-229. doi:10.1115/DETC2009-86076.

Today, air travel is popular as a way of transportation for different purpose such as business and tourism. The numbers of air travel passengers are increasing every year. At the same time the flight distance is increased because of better fuel efficiency and technology advancement of airplanes. Sitting is the most common activity during the flight. The US Department of Health advised the disable people to change their sitting posture frequently to relieve sitting pressures at least every 1 hour, and every 15 minutes for normal people. Decubitus is widely recognized as serious complication for a person with spinal cord injury. Motor paralyses affected a person’s ability to respond unconsciously to potential noxious stimuli. Decubitus affect the quality of life of spinal cord injury patient. For the spinal cord injury patient who travels with long haul flight, which is more than 5 hours, the decubitus risk will increase. The paper describes the development of an adaptive posture advisory system for spinal cord injury passengers. The aim of the system is to reduce the decubitus risk of the spinal cord injury patient during long haul flight.

Topics: Wounds , Spinal cord
Commentary by Dr. Valentin Fuster
2009;():231-240. doi:10.1115/DETC2009-86416.

This article deals with a methodology for the computer-aided design of electromechanical actuators. In the frame of the preliminary design, it focuses on the selection and sizing of various components used in the actuator architectures. The addressed design criteria are the mass and reliability for given effort and speed profiles. The developed library of components for the simulation takes advantage of the non-causal and object oriented characteristics of the Modelica language. Thus, the library models can carry out an inverse simulation of the energy flows going from the mechanical load to the power source. Additionally, the number of parameters to be entered by the user has been minimized by the use of scaling laws, which return all the parameters that are necessary for the simulation. At the end of the article, the proposed approach is illustrated with the sizing and comparison of actuator architectures for an aircraft landing gear steering system.

Commentary by Dr. Valentin Fuster
2009;():241-245. doi:10.1115/DETC2009-86656.

We propose a new approach to an automatic source code generator for the AUTOSAR-based vehicular software. The growing number of electrics/electronics software in vehicle systems makes more and more necessary the increasing demands. For example, it needs the essential requirements such as ensuring reliability, low production cost, coping with limited resources, and so on. Recently, there have been relative studies that point to this issue. An AUTOSAR development partnership is such a case. AUTOSAR is a standardized automotive software architecture which is an alliance of OEM and supplier. Now, the focus is mainly directed at a source code generator that deals with the AUTOSAR standard concept. In this paper, we present a novel source code generator which is based on the AUTOSAR software platform. The experimental process is presented to functionally verify the module, and structurally verify the generated source code.

Topics: Generators
Commentary by Dr. Valentin Fuster
2009;():247-254. doi:10.1115/DETC2009-86658.

The adaptronic precision positioning technology is applied to the fitting of rotation-symmetric components such as gearwheels in a hard turning process in order to compensate eccentricity. Distorted gearwheels, showing e.g. a significant quench distortion, cause a malposition in the chuck during clamping. This malposition leads to low quality workpieces or scrap in the hard turning process. To compensate the malposition of the workpieces, a new technology for precision positioning within the rotating chuck is being researched. In the introduction, the motivation of the preceding research project “Allowance-oriented precision positioning” and the framework of the adaptronic precision positioning technology are summarized. Next part is the description of the system’s components, beginning with the principles and the redesign of the mechatronic chuck. Completing the adaptronic precision positioning technology, the optical metrology, the data processing and automation aspects are shown in the following part. Afterwards, a short summary concludes this paper.

Commentary by Dr. Valentin Fuster
2009;():255-261. doi:10.1115/DETC2009-86802.

This paper presents a virtual vehicle simulator for testing networked embedded systems. These days a vehicle can include up to one hundred electronic control units. These control units are connected via communication media in order to improve the performance of vehicles. However, it is not an easy process to test electronic control units in real vehicles. Thus, we propose a virtual simulation of a vehicle which is controlled by an embedded network system. The simulator provides the essential requirements necessary to accurately test networked embedded systems. The proposed simulator provides a three-dimensional (3D) modeled virtual vehicle which is controlled by multiple networked embedded systems that transmit information to the simulator via LIN, CAN, and FlexRay communication protocols. This simulator enables us to predict the vehicle’s dynamics and communication problems.

Commentary by Dr. Valentin Fuster
2009;():263-272. doi:10.1115/DETC2009-86954.

In many cases, the quantitative relevance of physical effects for a given technical problem is not known a priori. This holds especially for the analysis of the dynamics. Adopted from nonanalog circuit design, in the last years symbolic model reduction techniques found their way towards mechatronic system modeling. Given a scenario (system inputs, initial values, parameters) and an error bound, symbolic model reduction reduces the detailed model to a less complex model, which is guaranteed to stay within predefined error bounds. However, presently symbolic reduction techniques deliver reduced models, which are only verified for a single scenario. For example a reduced vehicle model emerging from the reduction of a complex multibody vehicle model for a cornering maneuver with a small constant steering angle, is not verified to stay inside the error bounds for any other maneuver. In this contribution this drawback is addressed by the use of interval-valued scenarios.

Commentary by Dr. Valentin Fuster
2009;():273-280. doi:10.1115/DETC2009-87033.

The main control tasks for automation of crane operation are load sway damping and load velocity tracking control. A non-linear dynamic crane model combines the equations of motion of the rope suspended load and approximations of the actuator dynamics. Using the flatness property of the crane model, a non-linear controller is obtained by feedback linearization. Smooth and feasible reference trajectories are generated as solutions of an optimal control problem. The control system is implemented at a LIEBHERR harbor mobile crane. Measurement results show the validity of the approach.

Commentary by Dr. Valentin Fuster
2009;():281-289. doi:10.1115/DETC2009-87443.

In this paper, the dynamic behavior of a cylindrical layerwise piezoelectric shell under moving load is studied. The load is an internal constant pressure moving with constant velocity. This type of loading is studied in this paper for the first time. After showing the validity of the proposed approach, the effects of various parameters such as the pressure, the inside diameter, the various type of piezoelectric materials and the thickness of cylinder are investigated.

Commentary by Dr. Valentin Fuster
2009;():291-297. doi:10.1115/DETC2009-87611.

This paper discusses the design of low-frequency pulse width modulation for heating ventilation and air conditioning (HVAC) compressors. HVAC units are traditionally controlled using nonlinear control techniques like hysteresis control. Using a very long pulse width, this method can treat an on/off air conditioner or heat pump compressor as a variable input for which traditional linear (or nonlinear) controls can be applied. The key advantage of this method is direct control over the compressor power using tunable saturation. Power control is especially useful when considering load management and real time energy pricing.

Commentary by Dr. Valentin Fuster
2009;():299-304. doi:10.1115/DETC2009-87853.

In this paper, a simple and powerful formulation is presented for probabilistic design of engineering systems. The challenging task of optimum allocation of errors to design variables is transformed into a simple zero degree of difficulty geometric programming problem. This method is based on a known state of the design (the design values as well as the linear mapping between the input and output of the system). Uncertainties of design variables are assumed to be independent, and normally distributed. Failure is defined as a constraint in the optimization process, and has the form of the probability of divergence of outputs from their allowable bounds. Then, this constraint is simplified into a deterministic bound within six sigma spread. Having a zero DOD problem, the optimal solutions are readily available for any system regardless of the complexity. Several numerical experiments are conducted to assess the efficiency of the proposed formulation. The results are compared with more exhaustive searches using Monte Carlo simulation. For higher order and complex systems, it is demonstrated that this formulation will be %20 more conservative than the exact Monte Carlo simulation.

Topics: Design , Optimization
Commentary by Dr. Valentin Fuster
2009;():305-312. doi:10.1115/DETC2009-86442.

A new mathematical model has been achieved, for the calculation of DFT and its inversion depending on the indices which represent the shortest way for referring to the elements, pixels or pixels in each slide dealing with 1-D, 2-D, and 3-D digital signals respectively. This method indicates clearly the contribution factor of each input signal element in each output signal element.

Commentary by Dr. Valentin Fuster
2009;():313-317. doi:10.1115/DETC2009-86930.

In order to let the student understand the linear motion module’ principles and know how to improve the dynamic performance and control accuracy, a mathematical model is established based on the analysis of the composition and working principle of linear motion module. On the load and unload conditions, we simulate and analyze the system respectively. In the load case, PID parameters are obtained after the PID regulation. The correction of establishing the mathematical model and simulating the system are verified so that the linear motion model’ precision is effectively enhanced.

Topics: Motion , Simulation , Modeling
Commentary by Dr. Valentin Fuster
2009;():319-324. doi:10.1115/DETC2009-87148.

Lectures and labs with hands-on trainings and project based aspects are of high relevance for courses dedicated to embedded systems design when the transfer of practical skills is a major objective. Therefore, small classes, good support and frequent access to target platforms over a long period of time are beneficial. Providing access to the latter, however, can become a hassle for the organizers, especially when multiple courses are to be held in parallel or when they are organized as asynchronous distance learning courses. The problem is even aggravated when the platforms should be kept at the fore-front of the state-of-the-art. For this purpose we present in this paper concepts and implementation guidelines of a remote lab infrastructure that addresses these issues. In particular, the presented approach keeps the efforts to migrate to new embedded targets simple, enables nearly 24/7 times of access, ideally complements on-site trainings, and keeps the required costs low.

Commentary by Dr. Valentin Fuster
2009;():325-334. doi:10.1115/DETC2009-87351.

The paper presents an hardware realization of a self-tuning control system implemented on a development board, Field Programmable Gate Arrays (FPGAs) based, able to adapt the control rules for an uncertain and disturbance affected plant. In the paper the on-line estimation of the plant parameters is realized by applying the “Recursive Least Squares with exponential forgetting” method and the control law is designed by using the “Pole Placement” procedure. These algorithms require a greater computational load, justifying therefore the FPGA utilization, especially in the case of high speed variation of the plant parameters. In order to test the FPGA hardware implementation of Self-Tuning regulators the process is implemented on DSPACE and the parameter variations are produced via an Human Machine Interface (HMI) console. Besides, thanks to the reprogrammability of FPGAs, these devices allow the use of such adaptive control systems in hazardous area.

Topics: Governors
Commentary by Dr. Valentin Fuster
2009;():335-340. doi:10.1115/DETC2009-86569.

Current researches on electric vehicles are focusing on the environment and energy aspects. However, electric motors also have much better control performance than the internal combustion engines. Electric vehicles could not only be “cleaner” and “more energy efficient”, but also become “safer” with “better driving performance”. In this paper, a discrete elasto-plastic friction model is proposed for a dynamic emulation of tire/road friction for developing control systems of electric vehicles. The friction model can capture the transient behavior of the friction force during braking and acceleration, therefore the model-based emulation could enable more reliable verifications for various electric vehicle control methods.

Commentary by Dr. Valentin Fuster
2009;():341-346. doi:10.1115/DETC2009-86969.

The motivation for this work is to develop a platform for a self-localization device. Such a platform has many applications for the autonomous maneuverable non-holonomic mobile robot classification, which can be used for search and rescue or for inspection devices where the robot has a desired path to follow but because of an unknown terrain, the device requires the ability to make ad-hoc corrections to its movement to reach its desire path. The mobile robot is modeled using Lagrangian d’Alembert’s principle considering all the possible inertias and forces generated, and are controlled by restraining movement based on the holonomic and non-holonomic constraints of the modeled vehicle. The device is controlled by a PD controller based on the vehicle’s holonomic and non-holonomic constraints. An experiment was setup to verify the modeling and control structure’s functionality and the initial results are promising.

Commentary by Dr. Valentin Fuster
2009;():347-356. doi:10.1115/DETC2009-87023.

In this paper, a moving-horizon based concept for estimating the driving load profile of a hybrid hydraulic truck is proposed. First, a simple model of the hybrid hydraulic drivetrain is given. Based on this model and vehicle data, a sensitivity analysis is performed to determine which (time-varying) model parameters must be known to represent the driving load adequately. As a major contribution of this work, a Moving Horizon Estimation (MHE) scheme is developed to estimate mass and road grade from standard measurement data. Starting from an intuitive nonlinear formulation of the optimization task, the setup is then transformed to a constrained linear quadratic problem. It is shown how additional sensor information can be easily incorporated into the optimization framework to enhance the estimates, since an identifiability analysis shows that the parameters are usually not clearly distinguishable. Finally, it is demonstrated how the estimated load profile can be used to evaluate the fuel savings potential of a hybrid hydraulic truck by computing the fuel optimal operating strategy and comparing it to non-hybrid and rule-based strategies.

Commentary by Dr. Valentin Fuster
2009;():357-364. doi:10.1115/DETC2009-87100.

A three-dimensional transient heat transfer model is developed for a sequential joining process (resistance welding) applied on thermoplastic composites. This process involves with moving a voltage source along a heating element that conducts the power throughout a resistive mesh, generating heat and melts and bounds two composite surfaces. The model developed here is used to predict the spatial and temporal variations in the current and temperature over the weld seam for different set of input variables. The model integrates both the resistive and thermal behaviours of components involved. The significance of this modeling approach is that it captures the movement of the electrical connection, simulating a sequential joining process along a continuous weld seam. The modeling results are compared with experimental data obtained by thermocouples and infrared camera, and accurately predict the trend of variations in weld temperature.

Commentary by Dr. Valentin Fuster
2009;():365-369. doi:10.1115/DETC2009-87204.

This paper presents a method that can be used to produce authentic highway height data using a set of probability distributions. A highway is considered as a complex road which can have any kind of possible geometrical variations. The presented method models highway heights by Rayleigh probabilistic distribution function. The proposed model is then used to produce a random road whose 3D representation is presented. The random roads generated using the proposed method can be used as input for vehicle modeling and simulation applications.

Commentary by Dr. Valentin Fuster
2009;():371-378. doi:10.1115/DETC2009-87354.

This contribution is based on previous work of the authors and emphasizes the dynamical behavior and design of a fuel-cell driven hybrid powertrain for small vehicles. From a given load profile, a brief discussion will be presented on how to size the fuel-cells and SuperCaps in stationary consideration. The dynamics of the load profile, however put requirements on the system components and affect strongly their life time, in particular the fuel-cells. Especially, the load profile used here which is based on a measured profile from an industrial fork-lift, is very dynamic with large and fast power peaks. Using a Hardware-in-the-Loop test rig of the whole system, two different topologies are used to investigate which one is best suited for a defined industrial application. Further on, conventional led-batteries and SuperCaps with equivalent weight and volume are compared as the energy storage of the system. Finally, a power management to avoid fast transients from the fuel-cells in order to mitigate a fast deterioration is implemented. It will be shown that Super–Caps with the so called Range Extender topology are best suited and an adaptive controller for the output voltage of the DC/DC-converter is used to prevent fast dynamics in order to increase their lifetime.

Topics: Design , Fuel cells
Commentary by Dr. Valentin Fuster
2009;():379-384. doi:10.1115/DETC2009-86158.

Backstepping based adaptive tracking control of non-holonomic mobile robots in the presence of both kinematic and dynamic parametric uncertainty is presented. The major challenge is the possible singularity phenomenon due to the approach of zero of the estimated input vector field entering the denominator of the control input, a common drawback of adaptive linearization-based schemes. A hybrid control approach, which switches between an adaptive and a robust control schemes, is developed for solving such a problem. It retains the advantage of an adaptive control approach to a greatest extent while avoiding the possible blowup of the torque inputs simultaneously. A case study on a specific Type (2; 0) mobile robot is provided in the final to verify the usefulness of the proposed design.

Commentary by Dr. Valentin Fuster
2009;():385-395. doi:10.1115/DETC2009-86423.

This paper discusses control problem of free-floating dual-arm space robot system with unknown payload parameters to track desired trajectory in inertial space, when the attitude of base is controlled and its location is uncontrolled. Combining the relationship of the linear momentum conversation and the Lagrange approach, the full-controlled dynamic equation and the Jacobian relation of free-floating dual-arm space robot are analysed and established. Based on the above results, for the case of free-floating dual-arm space robot system with unknown payload parameters, a composite control scheme is designed on the base of a computed torque controller and a fuzzy compensator to track desired trajectories in inertial space, i.e., balancing the effect of system unknown payload parameters on computed torque controller with fuzzy adaptive compensator, in order to ensure the whole closed-loop control system asymptotic stability with the existence of unknown payload parameters. The mentioned control scheme can effectively overcome the effect of system unknown payload parameters and control both the base attitude and the end-effector of dual-arm space robot, so that they can track the desired trajectory in inertia space, with obvious advantages neither the mentioned control scheme needs to measure and feedback the position, velocity and acceleration of the floating base, nor the mentioned control scheme needs to requirements for the dynamic equations of the system inertial parameters in linear function. A two planar dual-arm space robot system is simulated to verify the effectiveness of the proposed control scheme.

Topics: Robots
Commentary by Dr. Valentin Fuster
2009;():397-404. doi:10.1115/DETC2009-86451.

This paper primarily addresses the design and implementation of a planar hexagonal Modular Self-Reconfigurable Robotic System (MSRRS) along with the construction of its reconfiguration path planner and control algorithm. A universal module is carefully designed to be in line with the common goals of MSRRS including homogeneity, cost-effectiveness, fast actuation and quick and strong connections. Although the implemented working prototype is both large and restricted to a planar geometry, it is designed such that its hardware and software can be scaled up in the number of units and down in unit size; similarly, the platform has the potential to be extended for 3D applications. The software infrastructure of this platform is designed in a way that different hierarchies for distributed control and communication can be implemented. The algorithmic design is based on a hierarchical multilayer approach, where upper layers decompose the problem into sub-problems solvable by lower layers. An optimal reconfiguration path planner is developed to minimize the number of module movements during the reconfiguration while enforcing collision avoidance and connectivity constraints in addition to taking into account the kinematic model of the platform. The core of the algorithm relies on a heuristic function and a Markov Decision Process (MDP) optimization to generate a near-optimal reconfiguration path planner and a control algorithm for HexBot shown in Figure 1, a lattice, homogenous, rigid, planar hexagonal MSRRS. Among several novel approaches incorporated in this system, multilayer nature of both hardware and software design provides openness, flexibility and ease of modification or adaptation for other platforms. In this approach each layer is dedicated to perform a specific task and can be modified or enhanced separately while keeping the remaining layers untouched.

Topics: Algorithms , Design , Robotics
Commentary by Dr. Valentin Fuster
2009;():405-410. doi:10.1115/DETC2009-87048.

This paper presents normal vector clustering method for environmental cognition using 3D laser radar. With the special design of 3D laser radar, accurate 3D depth of field data can be obtained. The proposed method acts on facet-unit, which is a description of the basic unit of 3D laser data. The novel method, which significantly reduces the amount of computation and improves the computational speed, is able to efficiently distinguish different flats in the 3D space. An embedded system is adopted as the platform for data processing and visualization. TinyGL is implemented on Qt-embedded to enhance the performance of environment map reconstruction and visualization. Experimental results validate the effectiveness of the 3D laser radar and cognition method developed.

Topics: Lasers , Radar
Commentary by Dr. Valentin Fuster
2009;():411-418. doi:10.1115/DETC2009-87500.

An algorithm for the simplified tele-operation of a mobile-manipulator system is presented. It allows for unified, intuitive, and coordinated control. Unlike other approaches, the mobile-manipulator system is modelled and controlled as two separate entities rather than as a whole. The algorithm consists of three states. In the first state, a joystick is used to freely control the manipulator’s position and orientation. The second state occurs when the manipulator approaches a singular configuration. This causes the mobile base to proceed in such a way as to keep the end-effector moving in its last direction. This is done through the use of a simple optimization routine. The third state is triggered by the user: once the end-effector is in the desired position, the mobile base and manipulator both move with respect to one another keeping the end-effector stationary and placing the manipulator into an ideal configuration. The proposed algorithm avoids the problems of algorithmic singularities and simplifies the control approach. A preliminary version of the algorithm has been implemented on the Jasper mobile-manipulator system with success.

Topics: Manipulators
Commentary by Dr. Valentin Fuster
2009;():419-426. doi:10.1115/DETC2009-87508.

Planetary exploration has already taken place for several years now using wheeled rovers. However, even though successful, these missions are limited to relatively flat and sedentary grounds. The areas explored are very interesting, but are of less importance from the point of view of searching for potential traces of life when compared to certain riskier zones. It is well understood that space agencies cannot afford the risk of using costly robots in these zones of uncommon geology. It is therefore anticipated that space exploration will evolve towards the use of small low-cost robots mobile enough to be used on rough terrains rich in geological information. This paper presents a small walking robot platform that was developed based on requirements provided by the Canadian Space Agency (CSA).

Topics: Robots
Commentary by Dr. Valentin Fuster
2009;():427-433. doi:10.1115/DETC2009-87610.

This paper presents a Rao-Blackwellized particle filter (RBPF) approach with a modified undelayed initialization scheme to solve the 3D visual SLAM problem (vSLAM) using a single camera. In the proposed method, landmarks are initialized using the inverse depth of the landmarks rather than the traditional use of their depths. In this scheme, there is no need to distinguish between partially and fully initialized landmarks. Once the landmarks are properly initialized, the RBPF enhances the estimation of the robot path and landmark location using bearing-only information obtained from a camera. The results of numerical simulations and experiments with a video clip have been included in this paper to verify the performance of the proposed approach.

Commentary by Dr. Valentin Fuster
2009;():435-441. doi:10.1115/DETC2009-87647.

A new novel breed of robots known as socially assistive robots is emerging. These robots are capable of providing assistance to individuals through social and cognitive interaction. The development of socially assistive robots for health care applications can provide measurable improvements in patient safety, quality of care, and operational efficiencies by playing an increasingly important role in patient care in the fast pace of crowded clinics, hospitals and nursing/veterans homes. 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: The robot’s ability to identify, understand and react to human intent and human affective states during assistive interaction. In particular, we present a unique non-contact and non-restricting sensory-based approach for identification and categorization of human body language in determining the affective state of a person during natural real-time human-robot interaction. This classification allows the robot to effectively determine its taskdriven behavior during assistive interaction. Preliminary experiments show the potential of integrating the proposed gesture recognition and classification technique into intelligent socially assistive robotic systems for autonomous interactions with people.

Commentary by Dr. Valentin Fuster
2009;():443-447. doi:10.1115/DETC2009-87654.

This paper deals with the forward displacement analysis and singularity analysis of a 2-DOF 5R spherical parallel manipulator. An alternative formulation of the kinematic equations of the 2-DOF spherical parallel manipulator is proposed. A formula is then derived to produce directly the unique current solution to the FDA of the 2-DOF spherical parallel manipulator. It is proved that the formula is associated with the same assembly mode and working mode as the reference configuration of the spherical parallel manipulator. Unlike other parallel manipulators, the 2-DOF 5R spherical parallel manipulator always undergoes self-motion in a Type 2 singular configuration, and the 3R leg of the 2-DOF spherical parallel manipulator also always undergoes self-motion in a Type 1 singular configuration.

Commentary by Dr. Valentin Fuster
2009;():449-457. doi:10.1115/DETC2009-87761.

Object recognition and pose estimation are essential for an object transportation system with mobile robots. This paper investigates an approach for pose (position and orientation) estimation of an ordinary object using a laser range finder mounted on the mobile robot. First the CCD camera of the robot finds and identifies an object to be transported in the work environment. On locating a color blob marked on the object, the robot adjusts its pose to move the color blob into the center of the camera frame. Finally a laser range finder is activated to compute the distance and the angle between the laser source and the object. The information acquired in this manner is utilized by the robot to determine a proper pushing location on the object to be transported to goal location. The developed methodology is verified by a series of physical experiments. In the experiments, the object is placed at different positions and orientations and the developed scheme is executed in order to establish its robustness.

Commentary by Dr. Valentin Fuster
2009;():459-469. doi:10.1115/DETC2009-86459.

Communication between a sink node and a PC can constitute a bottleneck for high data rate applications of wireless sensor networks (WSNs) including, but not limited to, structural health monitoring, condition monitoring, wireless surveillance and patient health monitoring. In this paper, we evaluate four different data acquisition alternatives for data-intensive WSN applications. We will concentrate especially on optimizing UART (universal asynchronous receiver transmitter) communication in conjunction with WSN applications. Furthermore, we propose a new method for sink node to PC communication, which is based on using a USB-connected data acquisition (DAQ) board that samples the node external I/O. This method can provide an efficient solution to transfer data from the sink node to PC at a reasonable cost. Wireless sink node converts the data received from the network into analog signal levels, which are sampled through the DAQ board connected to a PC, and the original data is reconstructed offline. Tests on a wooden bridge built to scale with six wireless sensor nodes and a sink node show that with the proposed method it is possible to collect the data from the network and transfer them onto the PC significantly faster than with the 115.2 kbps UART communication regularly used in WSN applications.

Commentary by Dr. Valentin Fuster
2009;():471-477. doi:10.1115/DETC2009-87150.

Most of classical robot systems are constructed by using a monolithic system with a predefined physical layout, unified model of programming and operation. There are, however, a number of tasks that can’t be solved with such systems or the use of a single system limits the performance. So, we think Distributed Mechatronic Systems are the most reasonable solution in the applied projects. Network Robotics, Multiagent Mobil Systems, Network Robotic Systems which usually uses sensors/actuators networks can be an applied approach to deploy some of the Distributed Mechatronic Systems. Some of the most important applied projects have been surveyed. Therefore, we have found there are too many bottleneck and challenges in Distributed Mechatronic Systems and they will be discussed in this paper.

Commentary by Dr. Valentin Fuster
2009;():479-485. doi:10.1115/DETC2009-87772.

This paper presents a Web-based data inquiry and real-time control of sensor’s operating mode for structural health monitoring sensor networks. The main objective of the presented system is to provide a Web interface for real-time sensor data visualization, sensor-level damage diagnosis, and control of sensor’s operating mode. Web services are available both on distributed sensor nodes and a data repository machine. Users can request Web pages hosted on the sensor nodes or the data repository machine by specifying corresponding sensor IDs. The ability of directly accessing data on sensor nodes via internet allows users to monitor a structure’s performance in a timely manner. The damage diagnosis algorithms implemented on the sensor nodes help users to assess the structural health conditions without the need of transmitting sensor data to a central data station. The presented system also provides the capability of dynamically changing sensor’s operating mode through the Web interface. This feature greatly enhances the flexibility of the system to accommodate different sensing needs and achieve a long lifespan. The system has been tested in the Laboratory to validate its capabilities.

Commentary by Dr. Valentin Fuster
2009;():487-493. doi:10.1115/DETC2009-87813.

This paper presents the development and performance study of a two-level wireless sensor network (WSN) for structural health monitoring (SHM). The lower-level network adopts low-power ZigBee protocol whereas the higher-level network employs high speed WiFi communication for long distance data transmission. To promote distributed data processing and damage diagnosis, the higher-level sensor nodes are designed to possess high computational capabilities. A reliable data transmission mechanism is implemented in the lower-level ZigBee network. To reduce the power consumption and quickly respond to extreme events, an event-driven monitoring approach is proposed. The impact of the coexistence of ZigBee and WiFi on the system’s performance is also studied.

Commentary by Dr. Valentin Fuster
2009;():495-500. doi:10.1115/DETC2009-87834.

Wired sensor systems are currently used to monitor the performance and health of electric motors. Since the sensors need to be wired, these systems can only use few sensor modalities which are generally insufficient to detect the wide range of faults in motors. Wireless sensors, on the other hand, allow access to sensors mounted in accessible locations and on rotating parts. They are easy to install and maintain. However, the reliability of the transmission due to electromagnetic interference and the fidelity of the data due to high winding temperatures inside the motor need to be examined. This paper studies the feasibility of wireless sensors inside a 200hp AC induction motor. Two wireless sensors are attached inside the motor — one on the stator frame and one on the rotating shaft. A wired sensor is attached on the outside of the stator frame to study the fidelity of data from the wireless sensor. The packet delivery performance as a function of spatial location in terms of direction and distance with respect to the base station and the fidelity of data received by the base station are studied. The results show that an average of 97% and 87.9% of the data from the wireless sensor attached on the stator frame and shaft respectively is received at the base station, thus showing that wireless sensors can be reliably used inside the motor.

Commentary by Dr. Valentin Fuster
2009;():501-510. doi:10.1115/DETC2009-86337.

The emergence of electro-active materials such as piezoelectric ones allows recently to think back actuating and sensing functions thanks to new principles of electromechanically conversion of energy. The interesting properties of these materials lead up to considering the generalization of their use in various applications such as automobile, aeronautics or machining. However this enthusiasm quickly goes away when a common engineer has to be confronted to the quasi absence of ready-to-be-used models of devices made of these materials [14]. This comes from the fact that piezoelectricity still remains the mind of the experts of materials. This is why in this paper we aim to formalize and wittingly simplify existing approaches of modeling piezo-actuators. Our goal is to make available to all a method of constituting at least a basic library of piezo-actuators models. This set of models is intended and designed to be completed by more deepen models integrating several aspects neglected in basic models.

Commentary by Dr. Valentin Fuster
2009;():511-517. doi:10.1115/DETC2009-86510.

Batch-fabrication of eyeball-like spherical micro-lens not only reduces micro assembly cost, but also replaces conventional ball-lenses or costly GRINs (Gradient Reflective Index) without sacrificing performance. Compared to the conventional micro-lenses made in a half-spherical geometry, the eyeball-like micro-lens is a sphere, which allows focusing light in all directions on the substrate surface, thus providing application flexibility for optical applications. The current eyeball-like spherical micro-lens is made using photoresist SU-8. This work develops a batch process at low temperature by spin-coating SU-8 on a surface of silicon wafer. The SU-8 thick film is patterned by UV lithography to form an array of holes for holding eyeball-like spherical micro-lens. The fabrication process employs bulk micromachining to fabricate an array of nozzles on the silicon wafer. Next, this process pours viscous SU-8 into the cavity of silicon wafer and presses it through the nozzle before reflow. The eyeball-like spherical micro-balls form by balancing between surface tension and cohesion. Varying the amount of SU-8 pressed through the nozzle controls the diameter of the balls. This paper designs a pattern with a 3 × 3 lens-array with a numerical aperture of about 0.38. Diameters range from 60 to 500 um. Optical measurements indicate a diameter fluctuation within 3% and an optical insertion loss is below 2.5dB with a wavelength of 635nm in a single-mode fiber (SMF). Therefore the eyeball-like spherical micro-lens is capable of increasing coupling efficiency.

Commentary by Dr. Valentin Fuster
2009;():519-524. doi:10.1115/DETC2009-86559.

In this study, the correlation between macroscopic and microscopic properties of the II-IV semiconductor compounds CdX (X = S, Se, Te) is investigated. Based on constructing orthonormal tensor basis elements using the form-invariant expressions, the elastic stiffness for cubic system materials is decomposed into two parts; isotropic (two terms) and anisotropic parts. A new scale for measuring the overall elastic stiffness of these compounds is introduced and its correlation with the calculated bulk modulus and lattice constants is analyzed. The overall elastic stiffness is calculated and found to be directly proportional to bulk modulus and inversely proportional to lattice constants. A scale quantitative comparison of the contribution of the anisotropy to the elastic stiffness and to measure the anisotropy degree in an anisotropic material is proposed using the Norm Ratio Criteria (NRC). It is found that CdS is the nearest to isotropy (or least anisotropic) while CdTe is the least near to isotropy (or nearest to anisotropic) among these compounds. The norm and norm ratios are found to be very useful for selecting suitable materials for electro-optic devices, transducers, modulators, acousto-optic devices.

Commentary by Dr. Valentin Fuster
2009;():525-533. doi:10.1115/DETC2009-87077.

In [1] we proposed an approach of formalizing piezo-bar actuator dynamics models in the engineer languages. The proposed models were based on a first approximation considering that the piezo-material is linear. However, as soon as the solicitations increase one will realize that this assumption is no longer valid because non-linearities are observed. And these phenomena can seriously affect the device performances. That is why several works are conducted in order to well understand the phenomena and eventually propose means of controlling them. So, above of all we shall give in this paper an overview of existing approaches. As said in [2], all these non-linearities in piezoelectric materials are well analyzed but mostly in the framework of the fundamental physics of crystals and thermodynamics and these descriptions are extremely difficult to handle. Therefore is important to make a bridge between the fundamental studies of piezoelectric materials and classical engineering field. It is actually the purpose of this paper. We will see that due to the complexity of the phenomena and especially numerical and algebraic troubles, some simplifications could be necessary.

Commentary by Dr. Valentin Fuster
2009;():535-538. doi:10.1115/DETC2009-87254.

This paper presents a design idea for an electric charging device designed to sit underneath the keypad of various mobile devices using piezoelectric and similar effect materials. It discusses the benefits of such a device and the current problems associated with developing one. The basis for the device is that multiple piezoelectric materials placed under the keypad are subjected to repeated loading from activities such as ‘texting’ or ‘menu browsing’. This causes a variable voltage generation which can assist in charging or other suitable function of the device. The paper shows the ways to achieve this goal and examine current piezoelectric generators.

Topics: Generators , Batteries
Commentary by Dr. Valentin Fuster
2009;():539-546. doi:10.1115/DETC2009-86151.

Hummingbirds and some insects exhibit a “Figure-8” flapping motion, which allows them to undergo variety of maneuvers including hovering. It is therefore desirable to have miniature air vehicle (FWMAV) with this wing motion. This paper presents a design of a flapping-wing for FWMAV that can mimic “Figure-8” motion using a spherical four bar mechanism. In the proposed design, the wing is attached to a coupler point on the mechanism, which is driven by a DC servo motor. A prototype is fabricated to verify that the design objectives are met. Experimental testing was conducted to determine the validity of the design. The results indicate good correlation between model and experimental prototype.

Commentary by Dr. Valentin Fuster
2009;():547-555. doi:10.1115/DETC2009-86412.

This paper provides an overview of the first participation of the design developed by the undergraduate students of American University of Sharjah to meet the requirements laid forth in the 2008 Association for Unmanned Vehicle Systems International (AUVSI) Student UAS competition. The overall objective of the competition is to fly autonomously over a GPS waypoint defined route and also to identify and locate ground based targets within a confined area. To meet the objectives an unmanned aircraft is equipped with autonomous functionality and aerial imaging system. A ground station and supportive software to keep track of the aircraft routine and log the raw data gained from the flight is also designed. Achieving complete success depends upon mission elements which include autonomous take-off and landing, autonomous control and waypoint navigation. The onboard equipment used was a flight control computer network, IMU, GPS, an air data system and a camera. Additionally, safety features such as manual override was also installed. Presented in this report are aircraft design and testing, the processes involved in accomplishing the goal, and the results and achievements.

Commentary by Dr. Valentin Fuster
2009;():557-566. doi:10.1115/DETC2009-86456.

Uninhabited vehicles can be used in many applications and domains, particularly in environments that humans cannot enter (e.g. deep sea) or prefer not to enter (e.g. war zones). The promise of relatively low cost, highly reliable and effective assets that are not subject to the physical, psychological or training constraints of human pilots has led to much research effort across the world. Due to technological advances and increasing investment, interest in Unmanned Aerial Vehicles (UAVs) as a practical, deployable technological component in many civil applications is rapidly increasing and becoming a reality, as are their capabilities and availability. UAV platforms also offer a unique experimental environment for developing, integrating and experimenting with many other technologies such as automated planners, knowledge representation systems, chronicle recognition systems, etc. UAV performs various kinds of missions such as mobile tactical reconnaissance, surveillance, law enforcement, search and rescue, land management, environmental monitoring, disaster management. UAV is a complex and challenging system to develop. It operates autonomously in unknown and dynamically changing environment. This requires different types of subsystems to cooperate. In order to realize all functionalities of the UAV, the software part becomes very complex real-time system expected to execute real-time tasks concurrently. This paper describes proposed software architecture for GCS (Ground Control Station) for lightweight UAV purpose-built for medium-scale reconnaissance and surveillance missions in civil area. The overall system architecture and implementation are described.

Commentary by Dr. Valentin Fuster
2009;():567-574. doi:10.1115/DETC2009-86490.

This paper describes Microraptor, a complete low-cost autonomous quadrotor system designed for surveillance and reconnaissance applications. The Microraptor ground station is custom-made and features a graphical user interface that presents and allows the manipulation of various flight parameters. The aerial vehicle is a 4-rotor vertical takeoff and landing (VTOL) vehicle that features the advantages of traditional helicopters with significant reduction in mechanical complexity. The vehicle frame is a handmade magnesium and carbon fiber structure. The onboard avionics system is a custom dual processor design capable of autonomous path navigation and data exchange with the ground station. The vehicle is outfitted with a video and still-photo system that provides real-time images to the system operator through the GUI. The system is being developed at Oakland University by a team of multidisciplinary undergraduate and graduate engineering students. Microraptor placed 5th at the 2008 Association for Unmanned Vehicle Systems International (AUVSI) Unmanned Aerial Systems (UAS) Competition and is set to compete again in June of 2009.

Commentary by Dr. Valentin Fuster
2009;():575-584. doi:10.1115/DETC2009-86500.

This paper, was originally prepared for and presented at the 2008 AUVSI Student UAS Competition, it provides the OSAM-UAV (Open-Source Autonomous Multiple Unmanned Aerial Vehicle) team’s design of an unmanned aircraft system for remote target recognition missions. Our OSAM-UAVs are designed to be small in size with strong airframes, and low-cost using open-source in both autopilot hardware and flight control software. A robust EPP-based delta wing airframe is used to prevent damage to the airframe during landing or even crashes. Autonomous navigation is achieved using an open-source Paparazzi autopilot, which gives special attention to safety during operation. Our system has been further enhanced by using the Xbow MNAV Inertial Measurement Unit (IMU) in place of the Paparazzi’s standard infrared (IR) sensors, for better georeferencing. An array of light-weight video cameras have been embedded in the airframe, which stream video to the ground control station through wireless transmitters in real-time. The ground control system includes a computer vision system, which processes and geo-references images in real-time for target recognition. Experimental results show the successful autonomous waypoint navigation and real-time image processing.

Topics: Design , Teams , Students
Commentary by Dr. Valentin Fuster
2009;():585-594. doi:10.1115/DETC2009-86547.

This paper presents the development and preliminary results of a rapidly reconfigurable autopilot for small Unmanned Aerial Vehicles. The autopilot presented differs from current commercial and open source autopilots mainly as it has been designed to: (i ) be easily reprogrammable via Simulink (models are directly transferred to the autopilot through the Real-Time Workshop’s code-generation capability); (ii ) decouple the traditional tasks of attitude estimation/navigation and flight control by using two Digital Signal Controllers (one for each task) interconnected via a Serial Peripheral Interface; and, (iii ) being able to interact directly with Simulink as a Hardware-in-the-Loop simulator. This work details each of the main components of the autopilot and its ground control station software. Preliminary results for sensor calibration, Hardware-in-the-loop, ground and flight tests are presented.

Commentary by Dr. Valentin Fuster
2009;():595-601. doi:10.1115/DETC2009-86725.

This paper describes the integration and application of the Paparazzi autopilot into an aircraft system for scientific research on remote sensing. The main purpose of the presented UAV, Stuttgarter Adler , is remote sensing of the environment for fundamental radiometric research as well as applications in agriculture, surveying and mapping. Employing a UAV for the retrieval of remote sensing data of quality comparable to data from manned missions represents a very flexible and inexpensive method of data acquisition. The sensors required for the intended resolution total several kilograms in weight and led to the construction of a matching airplane. All intended missions require a robust and precise control of the aircraft during image acquisition flights, which can only be achieved with an automated pilot assistance system. The Paparazzi system was chosen because its open source approach allowed to adapt the autopilot to the specific mission requirements. Interfaces to the digital remote control and to the camera and spectrometer payloads have been created. Test flights show good results in stabilizing the airplane and controlling the payload.

Commentary by Dr. Valentin Fuster
2009;():603-609. doi:10.1115/DETC2009-87107.

Nitrogen deficiency can seriously reduce yield, while over-fertilization can result problems such as excess nutrient runoff and groundwater pollution. Hence, efficient methods for assessing crop nitrogen status are needed to enable more optimal fertilizer management. The ability to quantify the different nitrogen application rates by crops using digital images taken from an unmanned aerial vehicle (UAV) was investigated in comparison with ground-based hyperspectral reflectance and chlorophyll content data from 140 plots on a managed field. This research utilized new UAV system, comprised of remote-controlled helicopter (Hercules II) and digital camera (EOS 30D), was used to characterize spatial and temporal variation in crop production. Digital information was extracted based on an object-oriented segmentation method, and the color parameter was reduced and represented using principal component analysis (PCA). An estimating model was established after analyzing the relationship between the optimal color parameter and ground-based measurements. Model testing demonstrated that unknown samples could be associated with the controlled nitrogen application rates (0, 60, 90, and 120 kg N·hm−2 ): 91.6% %; N1 (60 kg N·hm−2 ): 70.83%; N2 (90 kg N·hm−2 ): 86.7%; N3 (120 kg N·hm−2 ): 95%. Overall, this result proved to provide a cost-effective and accurate way and the UAV was an exploratory and predictive tool when applied to quantify different status of nitrogen. In addition, it indicated that the application of digital image from UAV to the problem of estimating different nitrogen rates is promising.

Commentary by Dr. Valentin Fuster
2009;():611-620. doi:10.1115/DETC2009-87136.

A real-time kinematic (RTK) global positioning system (GPS) has been identified for potentially being used as a ground-truth sensor for testing robotic rovers for planetary exploration. A series of environmental tests needs to be performed in order to validate the performance of the sensor at hand before being used as a ground-truth system. This paper focuses on the performance evaluation of the RTK GPS at Axel Heiberg Island Canadian Space Agency’s Analogue Research Network (CARN) site. This is one of the officially recognized terrestrial analogues, that is places on Earth that approximate the geological, environmental and putative biological conditions on Mars and other planetary bodies (Hipkin et al.). The challenge lies in the use of the equipment at Arctic latitudes. The results show that the system performed according to specifications even in this challenging environment.

Commentary by Dr. Valentin Fuster
2009;():621-628. doi:10.1115/DETC2009-87574.

This paper focuses on designing and implementation of fractional order proportional integral (PIα ) flight controller on a small fixed-wing unmanned aerial vehicle (UAV). It describes mainly the controller design and simulation studies. The basics of UAV flight control are introduced first with a special emphasis on small UAV platforms. Time domain system identification methods are tried on the UAV roll channel. A new fractional order PI controller design method is then provided based on the identified first order model. The fractional order PIα controller can outperform the traditional integer order PID controller because it has a larger memory and more candidate solutions to choose. The simulation results show the effectiveness of the proposed controller design strategy and the robustness of fractional order controller under conditions of wind gusts and various pay-loads.

Commentary by Dr. Valentin Fuster
2009;():629-634. doi:10.1115/DETC2009-87586.

Small, low-cost unmanned aerial vehicles (UAV) has made data acquisition more convenient and accessible for many applications. Using multiple UAVs (a coven) brings even more advantages like redundancy and distributed information. The objective of this paper is to show how a coven of UAVs can help two applications: measuring wind and 3D photogrammetry.

Commentary by Dr. Valentin Fuster
2009;():635-640. doi:10.1115/DETC2009-87636.

Small UAV performance is limited by the sensors used in the navigational systems. Several solutions of various complexity and cost exist, however no ready-made solutions exist for a high-accuracy, low-cost UAV system. Presented is AggieNav: a small, integrated navigational 6 degree-of-freedom with compass and GPS sensor package designed for ideal navigation of small UAVs. System, hardware, and embedded software design for the system is detailed.

Commentary by Dr. Valentin Fuster
2009;():641-647. doi:10.1115/DETC2009-87671.

Small UAV performance depends on an effective and efficient command system architecture. Based on an existing UAV system called Paparazzi, AggieAir is a full flight system capable of handling single or multiple UAVs with single or multiple payloads per airframe. System-level block diagrams are presented and specific details about implementation and results are provided.

Commentary by Dr. Valentin Fuster
2009;():649-654. doi:10.1115/DETC2009-87675.

Small UAV performance is limited by the sensors and software filters used in the navigational systems. Several solutions of various complexity and cost exist, however no ready-made solutions exist for a high-accuracy, low-cost UAV system. Presented is the design (low-level system as well as high-level extended Kalman filter) for a specifically designed small-UAV navigation platform, AggieNav.

Commentary by Dr. Valentin Fuster
2009;():655-662. doi:10.1115/DETC2009-87741.

In this paper, we have developed a light-weight and cost-efficient multispectral imager payload for low cost fixed wing UAVs (Unmanned Aerial Vehicles) that need no runway for takeoff and landing. The imager is band-reconfigurable, covering both visual (RGB) and near infrared (NIR) spectrum. The number of the RGB and NIR sensors is scalable, depending on the demands of specific applications. The UAV on-board microcomputer programs and controls the imager system, synchronizing each camera individually to capture airborne imagery. It also bridges the payload to the UAV system by sending and receiving message packages. The airborne imagery is time-stamped with the corresponding local and geodetic coordinates data measured by the onboard IMU (Inertia Measurement Unit) and GPS (Global Positioning System) module. Subsequently, the imagery will be orthorectified with the recorded geo-referencing data. The application of such imager system includes multispectral remote sensing, ground mapping, target recognition, etc. In this paper, we will outline the technologies, demonstrate our experimental results from actual UAV flight missions, and compare the results with our previous imager system.

Commentary by Dr. Valentin Fuster

20th Reliability, Stress Analysis, and Failure Prevention Conference

2009;():665-670. doi:10.1115/DETC2009-86324.

As a flexible maintenance strategy, Condition Based Maintenance (CBM) has been accepted by industry due to its efficiency and robustness in many engineering practices. Successful implementation of CBM relies on observation of actual health condition of machinery. Therefore, it is crucial to perform condition monitoring in CBM. This paper focuses on quantifying health condition of machinery. Empirical Mode Decomposition (EMD) is employed to decompose signal and extract dominant signatures, which could reflect health condition variation of machinery. Then, a novel index called Health Index (HI) is proposed to describe condition development trends. In order to detect occurrence of early faults, a dynamic threshold is also proposed. In case occurrence of early fault, HI should be higher than its corresponding threshold. This novel condition monitoring method is more appropriate for on-line health monitoring and detection of incipient fault. Two sets of data collected from gearboxes are used to validate the proposed method. The analysis results show that the proposed method is effective in condition monitoring, especially the detection of early faults.

Commentary by Dr. Valentin Fuster
2009;():671-678. doi:10.1115/DETC2009-86836.

The qualified application of the finite element method as an important tool in the virtual engineering design process requires extensive methodological skills, competence and experience of the design engineer. There is no relevant support provided by commercial software tools. In the recent past several ideas have been proposed and tested in order to implement error controlled dimensional and model adaptivity techniques in combination with h- or p-refinement strategies. For deriving a finite element model with less degrees of freedom for time domain simulation the model adaptivity as well as the dimension adaptivity can be utilized. The application of such error controlled modeling techniques leads to finite element models consisting of domains with different local meshes and a combination of different model dimensions, such as beams, plates, shells and 3D continua. These domains have to be coupled to gain a holistic finite element model for the simulation of the local as well as the global behaviour of a system. There are different coupling methods available, each resulting in more or less additional errors, which have to be taken into account. In the paper several methods for coupling of different domains of a complex structural system are presented. They are tested with regard to their quality and their suitability in an error controlled model adaptation procedure.

Commentary by Dr. Valentin Fuster
2009;():679-684. doi:10.1115/DETC2009-86995.

A systematic reliability analysis of n-unit warm standby repairable system with k-repair facility is presented in this paper. Traditional approaches are extended under the following assumptions: (1) the working lifetime, the standby lifetime, and the repair time of failed units are represented as exponential distribution; and (2) the repair of failed units are as good as new after repair. In this paper, a general reliability analysis of an n-unit warm standby repairable system with k-repair facility is presented. Based on previous analysis, the steady-state reliability and the average availability of the system are formulated using the Markov process theory and Laplace transform.

Commentary by Dr. Valentin Fuster
2009;():685-694. doi:10.1115/DETC2009-87442.

The finite element method is used to analyse the through-the-width stress distribution characteristics of single and multiple delaminated cantilevered composite beams. Single delaminations of fixed length, which are located at different through-the-thickness locations, and multiple delaminations of sequential and diagonal configurations are investigated. The total length of multiple delaminations in a beam was made equal to the fixed length of a single delamination. The results show that the configurations and spatial distributions of multiple delaminations have significant effects on the magnitude of the maximum stresses induced in the beams. Beams in which most of the delaminations are concentrated around the mid-plane of the beam show higher stresses than beams in which most of the delaminations are concentrated close to the surface of the laminate. However, delaminations close to the surfaces of the beams exhibit higher stresses at the tips of the delaminations.

Commentary by Dr. Valentin Fuster
2009;():695-701. doi:10.1115/DETC2009-86193.

The three-dimensional geometric model of the fringe-beam frame had been built based on the frame structure of a light truck. In order to optimize the frame structure, the finite element model of the frame and the suspension system were set up. Considering the influence of suspension on frame dynamic performance, the modal properties of the frame model was analyzed in the commercial analysis program ANSYS, using two different methods. Based on the experiments, it was verified that combining MPC184 elements and spring elements Combin14 is a better way to simulate suspension compared to using spring finite elements only. Furthermore, the combined simulation results coincide with experimental modal analysis results, which were conducted thereafter. Subsequently, the frame stress-strain distribution rules and dynamics response were calculated under the random road spectrum excitation, and the frame dynamic parameters were obtained. This study provides some theoretical bases for frame structure improvement, and proposes an optimum method to simulate suspension. The results have direct significance in ensuring the stability, comfort and reliability of a light truck frame.

Commentary by Dr. Valentin Fuster
2009;():703-710. doi:10.1115/DETC2009-86441.

This paper concerned with analysis of fatigue crack growth behavior of Friction Stir Welding (FSW) joints, by the comparison of boundary element method simulation results with experimental investigation of FSW Al 2024 alloy. Crack propagation in different FSW joint zones was studied using Paris and Forman-Newman-de Koning models and fatigue life estimation provided good agreement with the experiments.

Commentary by Dr. Valentin Fuster
2009;():711-717. doi:10.1115/DETC2009-86585.

The present paper further develops The Fractal-like Finite Element Method (FFEM) to compute the stress intensity factors (SIFs) for non-symmetrical configurations of sharp V-notched plates. The use of global interpolation functions (GIFs) in the FFEM significantly reduces the number of unknown variables (nodal displacements) in a singular region surrounding a singular point to a small set of generalised coordinates. The same exact analytical solutions of the notch tip asymptotic field derived for a symmetrical notch case can be used as GIFs when the notch is non-symmetrical. However, appropriate local coordinate transformation in the singular region is required to obtain the correct global stiffness matrix. Neither post-processing technique to extract SIFs nor special singular elements to model the singular region are required. Any conventional finite elements can be used to model the singular region. The SIFs are directly computed because of the use of exact analytical solutions as GIFs whose coefficients (generalised coordinates) are the unknowns in the singular region. To demonstrate the accuracy and efficiency of the FFEM to compute the SIFs and model the singularity at a notch tip of non-symmetrical configurations of notched plates, various numerical examples are presented and results are validated via available published data.

Commentary by Dr. Valentin Fuster
2009;():719-724. doi:10.1115/DETC2009-87006.

In general, information contains both of the physical attributes and the psychological attributes. For these two kind attributes of information, this paper discussed the incompleteness of the axioms system of the current information entropy theories. It is necessary to add the condition of boundedness to the axioms system when it is used to measure the uncertainty of psychological information. A new family of information entropy using a convex-concave function is introduced for satisfying the psychological attributes of information. And based on the psychological information entropy function, the divergence measures between two probability distributions of psychological information defined as Wang-Huang divergences are formulated. For the boundedness attributes of the psychological information entropy function and not requiring the condition of absolute continuity to be satisfied by the probability distributions involved, Wang-Huang divergences are totally different with the Kullback-Leiber divergences. The new measures are well characterized by the properties of non-negativity, finiteness. More importantly, their close relationship with the variation and the probability of misclassification error are established in terms of bounds illustrated in numerical examples. These bounds are crucial in many applications of divergence measures such as in the quality and reliability engineering applications.

Topics: Reliability , Entropy
Commentary by Dr. Valentin Fuster
2009;():725-729. doi:10.1115/DETC2009-87097.

In recent years, the application of Flexible Display (FD) is increasing dramatically due to its high brightness, high contrast, and large angle of view. Also because the substrate polymer material is flexible, FD is easily and widely used in various electronic packages. The competition of products based on these technologies such as electronic paper and mobile screen can be improved. In most of these applications, failure of FD can directly lead to failure of device. However, reliability data on FD are not commonly available in published literature, and the reliability of FD in practical application has not been studied very well. This paper presents an experimental study of FD with focus on its reliability under varying temperature and humidity conditions. The purpose of this paper is to investigate the failure mode of FD based on environmental test including steady damp heat test, dry heat test, cyclic damp heat test and cold test. The failure modes are discussed and the analysis is presented. In this study, all tests are conducted with visual inspections during each test procedure.

Topics: Reliability
Commentary by Dr. Valentin Fuster
2009;():731-737. doi:10.1115/DETC2009-86981.

This paper focuses on mechatronic systems reliability assessment during the development process phases. Modern technical systems safety requirements are regulated by law, especially the level of safety relevant systems or components. This means it is necessary to decide at early design phase which topology or hardware suites the safety requirements of the system. Therefore the first step is to detect the system impact factors, model the system architecture, and generate a topology tree. One possibility to describe the system architecture is given by the use of the Unified Modeling Language (UML). From the system architecture descriptions MATLAB/Simulink models can be generated. Subsequently the next step is the realization of a reliability-oriented topology, which can be used to consider reliability-oriented aspects.

Topics: Reliability , Design
Commentary by Dr. Valentin Fuster
2009;():739-744. doi:10.1115/DETC2009-86997.

It is necessary to combine reliability-based design and robust design in the practical engineering. In this paper, a unified framework for integrated reliability-based design and robust design is proposed. In the proposed framework, traditional multi-objective optimization problem is converted to a single objective optimization problem to integrate reliability-based design and robust design without weight factors. The conversion from probabilistic objective function to deterministic objective function is achieved by inverse reliability strategy under the consideration of the probabilistic characteristic of the objective function. After that, an improved sequential optimization and reliability assessment (SORA) method is proposed to deal with the unified framework. Overall, two examples are implemented to illustrate the benefits of the proposed methods.

Commentary by Dr. Valentin Fuster
2009;():745-750. doi:10.1115/DETC2009-86998.

Reliability Based Multidisciplinary Design Optimization (RBMDO) has received increasing attention to reach high reliability and safety in complex and coupled systems. In early design of such systems, however, information is often not sufficient to construct the precise probabilistic distributions required by the RBMDO and consequently RBMDO can not be carried out effectively. The present work proposes a method of Possibility Based Multidisciplinary Design Optimization (PBMDO) within the framework of the Sequential Optimization and Reliability Assessment (PBMDO-SORA). The proposed method enables designers to solve MDO problems without sufficient information on the uncertainties associated with variables, and also to efficiently decrease the computational demand. The efficiency of the proposed method is illustrated with an engineering design.

Commentary by Dr. Valentin Fuster
2009;():751-757. doi:10.1115/DETC2009-87003.

Diesel engine is a multi-disciplinary complex system with the harsh working environment and high reliability requirements. Its design for satisfying the basic reliability requirement is a high-demanding work. Correspondingly the reliability prediction is served as an important tool for reliability design. However, in the traditional reliability method, the analytical outcome obtained from the conventional FMECA was not always sufficient. This increases the workload of designers in charge of reliability, and reduces the working efficiency. Therefore, this paper conducts an in-depth research with the emphasis on the diesel engine’s reliability prediction, in which the failure mode and the information of criticality provided by FMECA will be made full use of to carry out the reliability prediction. Meanwhile, to make the prediction results more objective and reasonable, this paper introduces the weight of experts, and provides a prediction model, in which the fuzzy analytic hierarchy process and the fuzzy comprehensive evaluation are combined to analyze the criticality of FMECA.

Commentary by Dr. Valentin Fuster
2009;():759-771. doi:10.1115/DETC2009-87103.

There are many reliability prediction methods applicable to mechanical systems design. This paper specifically discusses the methods of probability or failure rate generation for reliability prediction. The paper consists of three parts. The first part is to survey the methods. We survey five most frequently used failure probability generation methods: statistical frequency and modeling method, similarity and comparative assessment method, physics based failure modeling, Monte Carlo simulation, and expert elicitation. We discuss the technical rationale and scientific foundation of each method and illustrate them with application examples. The second part is to evaluate and compare the methods. We identify the following attributes for evaluating and ranking the methods: the closeness of the method to the design; the validity and fidelity of the prediction results; the extensiveness of the analysis effort involved and data needs; the applicability of the methods at different product life cycle stages; and the limitations and cautions of using the prediction results to assist design-for-reliability. The third part is to establish a selection framework from applicable methods based on the ranking result of the second part, to assist practical use of the methods for mechanical design-for-reliability.

Topics: Reliability , Design
Commentary by Dr. Valentin Fuster
2009;():773-776. doi:10.1115/DETC2009-87206.

This paper proposes a novel linear regression with fuzzy weight method, which can eliminate the effect of the abnormal test data on the linear regression and is used to determine crack growth rate curve. Integrating various stochastic and fuzzy factors, and using probability crack growth rate curve and fuzzy probability crack growth rate curve, a novel method of fuzzy reliability analysis of crack life is proposed. A case study is given to demonstrate the effectiveness of the proposed methods.

Commentary by Dr. Valentin Fuster
2009;():777-780. doi:10.1115/DETC2009-87615.

In this paper, reduction factor, which describes the degree of service age reduction resulting from the preventive maintenance, is introduced into a condition-based maintenance strategy. The model determining the sequential test intervals is formulated under the constraint that the probability that the failure has not test successfully within each test interval should be less than a fixed threshold. The failure risk of deteriorating system can be reduced via shortening test interval. The effectiveness of the presented methods is illustrated via a numerical case.

Commentary by Dr. Valentin Fuster
2009;():781-784. doi:10.1115/DETC2009-87795.

Friction-induced self-sustained oscillation result in a very robust limit cycle that characterizes stick-slip motion. This motion should be avoided because it creates unwanted noise, diminishes accuracy, and increases wear. The stick-slip motion produced by a mass-spring-damper on a moving belt is analyzed using Lyapunov second method, which is based on constructing a positive definite function and checking the condition for which its time derivative is negative semi-definite. From this condition an estimate of the amplitude of the velocity of the limit cycle of the stick-slip motion is obtained. This estimate is found to be the zero of a certain function derived from the Coulomb friction model. An estimate of the amplitude of the displacement is also found. It is shown that the simulation results of the amplitude and the estimated amplitude are in a good match.

Commentary by Dr. Valentin Fuster
2009;():785-790. doi:10.1115/DETC2009-87830.

We devised a novel technique to fabricate composite cylindrical helical springs using glass, and carbon fibers and in hybrid form, embedded in a matrix of epoxy resin, thus introducing a novel approach to spring making by incorporating the versatility of the filament winder. Our method allows us to vary the dimensions of the spring with considerable ease. This is accomplished in three stages. The first stage involves the proper selection of the resin and hardener. In the next stage, the glass and carbon fibers are completely soaked in a resin bath and encased in PVC tubing of three different inner diameters, which determine the wire diameter of the composite spring. Using a filament winding technique, these fiber filled tubes are wound on PVC mandrels of three different diameters. The natural frequencies of the manufactured composite springs were measured experimentally to study the influence of dimensional parameters, i.e., diameter ratios (D/d) and number of active turns (N = 6 and 7) on the free vibration frequencies. The natural frequencies for glass and carbon fiber and hybrid springs were measured using an MTS fatigue tester, and the resonance of the springs were captured using a digital camera.

Commentary by Dr. Valentin Fuster
2009;():791-798. doi:10.1115/DETC2009-86086.

Oil peening is a new surface modification technique developed to introduce compressive residual stresses in metallic components. The magnitude and distribution of residual stresses and plastic strain in the oil peened AA6061-T4 alloy was evaluated using finite element method (FEM). The simulation of single drop impact against a plastically deformable material was performed. The contours of stress components are presented to show the formation of residual stress distribution. Finite element analysis reveals that the stress and strain patterns around the impact region of an oil drop during loading and unloading with different impact pressures. Impact pressure significantly influences the axial displacement, residual pileup and residual stress.

Commentary by Dr. Valentin Fuster
2009;():799-804. doi:10.1115/DETC2009-86334.

Due to inherent scatters in fatigue test data, the P-S-N curves are normally used to describe material fatigue behaviors. For probabilistic component’s design under fatigue loadings, the component’s dimension should be treated as a random variable because every dimension is certainly with a dimension tolerance. In this design scenario, it is difficult to determine the component’s dimension under fatigue loadings by using the P-S-N curves because stress levels are unknown and random variables. In this paper, a probabilistic approach is presented to build a generic probabilistic design equation which is governed by random variables related to material fatigue behaviors, component conditions and fatigue loadings. The generic probabilistic design equation can be used to determine component’s dimension with a given reliability. One example is presented for explaining the approach in details.

Topics: Fatigue , Dimensions
Commentary by Dr. Valentin Fuster
2009;():805-809. doi:10.1115/DETC2009-86371.

Flexible bearing system composed of diaphragm springs are a key component part of miniature Stirling cooler with linear motors. The stress distribution, the natural frequency, and visualization of the deformation of the diaphragm spring are investigated by finite Element method. From the calculation results of deformation pattern, it is confirmed that the calculation models and methods are appropriate. The stress calculation results reveal that the stress concentrations occur in some special parts of the diaphragm spring, such as root, and middle narrowest parts of the arms. The axial stiffness has the linear relation while the radial stiffness has the non-linear but hyperbolic relation with the disc thickness. The calculation results are in good agreement with the experimental results. The calculation results have been used to optimize the shapes of the diaphragm spring and manufacturing process.

Commentary by Dr. Valentin Fuster
2009;():811-817. doi:10.1115/DETC2009-86471.

Condition monitoring and fault diagnosis of bearings are of practical significance in industry. In order to get a feature containing different fault signatures, this paper uses Wavelet Transform (WT), Wavelet Lifting Scheme (WLS) and Empirical Mode Decomposition (EMD), respectively, to decompose signal into different frequency bands. Then, Singular Value Decomposition (SVD) is utilized to extract intrinsic characteristic of signal from obtained matrix. These singular value vectors are regarded as inputs to Hidden Markov Models (HMM) for identification of machinery health condition. In this research, the fault diagnosis system is validated by motor bearing data, including normal bearings, inner race fault bearings, outer race fault bearings and roller fault bearings. Analysis results show that this method is effective in bearing fault diagnosis and its classification rate is excellent.

Commentary by Dr. Valentin Fuster
2009;():819-825. doi:10.1115/DETC2009-86747.

The sealing contact pressure is one important parameter in evaluating the sealing performance of vane seals. The paper proposes a new numerical approximation method to calculate contact pressures in vane seals. The model considers the fact that the seal, made by the elastomeric rubber, is nearly incompressible and can’t be compressed in three principal directions at the same time. Being compressed in two of the three principle directions, e.g. in y and z directions, the seal expands in the third direction, namely, the x-direction. With reasonable results derived in the model, the width of the vane groove for the seal should be a little wider than the initial width of the seal. The results are in consistent with classical sealing theories and experiments on O-ring seals.

Commentary by Dr. Valentin Fuster
2009;():827-832. doi:10.1115/DETC2009-86857.

For the purpose of reliability assessment of continuous system like long pipeline and wire cable, the object should be taken as a series system composed of a great number of segments. First of all, two factors concerning the strength distribution of the object, i.e. material inhomogeneity factor and material quality instability factor were discussed in detail. Then, a reliability mathematical model of the object considering dependent failure was presented based on order statistics of segment strength, which was verified by Monte Carlo method. The result shows that the proposed reliability model can reflect the effects of dependent failure, material inhomogeneity and material quality instability for the application of continuous system.

Commentary by Dr. Valentin Fuster
2009;():833-838. doi:10.1115/DETC2009-87034.

Based on Continuum Damage Mechanics, an isotropic damage model is developed to give a damage-coupled localized necking criterion. Hill’s 1948 quadratic yield criterion and flow theory are employed to describe anisotropic plasticity of sheet metal during forming procedure. Sheet forming experiments in three stress states and density measurement test have been performed on IF steel, and then the damage data obtained are used to validate numerical results based on the damage-coupled model. As for the proportional loading, a simple expression of limit strains has been obtained to predict the forming limit curve. Then the forming limit diagrams predicted by this damage-coupled anisotropic model have been validated with experimental data for two kinds of sheet metal. Also the influences of material properties on forming limit curves are discussed.

Topics: Steel
Commentary by Dr. Valentin Fuster
2009;():839-845. doi:10.1115/DETC2009-87164.

The paper presents an experimental study on precipitation of 6061-T6 aluminum alloy to determine the effects of artificial ageing on the effect of strength. The precipitation hardening usually undergoes a thermal treatment, which consists of a solution heat treatment (550°C for 1 hour), quenching (water, at room temperature) and artificial ageing. The experimental study is focused on artificial ageing upon which the temperature is varying between 175°C to 420°C at different period of time. The Vickers hardness test was carried out to evaluate the hardness before and after ageing. The optimum ageing time and temperature were also determined at the end of this experiment to obtain reductions in energy and total cost. The study leads to the conclusion that the optimum aged can be achieve within 175°C to 195°C with 2 to 6 hours of ageing time.

Commentary by Dr. Valentin Fuster
2009;():847-851. doi:10.1115/DETC2009-87200.

The paper mainly presented mechanical test and failure analysis methods to reliability study of a new FPCB (Flexible Printed Circuit Boards). Mechanical tests include flexural test, tensile test and flexural fatigue and ductility test. As to simulation analysis, the stress distributions of FPCB under bending and tensile conditions were gained by simulations. Through in-depth analysis of the testing results, the mechanical reliability of FPCB was known detailed. The research provides an approach to improve FPCB performance.

Commentary by Dr. Valentin Fuster

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