Search

In this work, the fabrication of Rochelle salt based piezoelectric structures is illustrated. Structures composed of paper and Rochelle salt are easily manufactured using simple processes. Both manufacturing and the material itself are environmental friendly. Additionally Rochelle salt is biocompatible. In the paradigm of a cleaner piezoelectric technology, the fabrication of active sensing or actuating devices is developed. Thus processing method, material and piezoelectric properties have been studied: (1) pure crystals are used as acoustic actuator, (2) properties of paper impregnated with Rochelle salt are detailed, (3) charge generation is demonstrated on the impregnated material. Actuating and sensing devices are reported in order to highlight the potential of this green piezoelectric material. [ABSTRACT FROM AUTHOR]

Abstract: Good cross-directional control of sheet variables in a paper machine depends on a number of factors. One such factor is the correct alignment of actuators with their corresponding responses. The alignment changes with time either locally or across the whole paper sheet due to a variety of reasons. In this paper, we provide an online mapping technique based on estimating the cross-correlation between actuator movement and the measurements. This procedure involves two steps–in the first step (called alignment monitoring) we determine if the current mapping is wrong at any CD position, and in the second step (called re-mapping), the alignment of actuators is corrected. The main advantage of this method is in its ability to re-align under closed loop conditions with minimal operational disruption. [Copyright &y& Elsevier]

This paper deals with aircraft trajectory control in the presence of model uncertainties and actuator faults. Existing approaches, such as adaptive backstepping and nonlinear dynamic inversion with online model identification, can be applied. However, since there are a number of unknown aerodynamic derivatives, the tuning of parameter update law gains is time-consuming. Methods with online model identification require excitation and the selection of a threshold. Furthermore, to deal with highly nonlinear aircraft dynamics, the aerodynamic model structure needs to be designed. In this paper, a novel aircraft trajectory controller, which uses the Incremental Nonlinear Dynamic Inversion, is proposed to achieve fault-tolerant trajectory control. The detailed control law design of four loops is presented. The idea is to design the loops with uncertainties using the incremental approach. The tuning of the approach is straightforward and there is no requirement for excitation and selection of a threshold. The performance of the proposed controller is compared with existing approaches using three scenarios. The results show that the proposed trajectory controller can follow the reference even when there are model uncertainties and actuator faults. [ABSTRACT FROM AUTHOR]

This paper presents an Internet of Things (IoT)-enabled dependable control system (DepCS) for continuous processes. In a DepCS, an actuator and a transmitter form a regulatory control loop. Each processor inside such actuator and transmitter is designed as a computational platform implementing the feedback control algorithm. The connections between actuators and transmitters via IoT create a reliable backbone for a DepCS. The centralized input–output marshaling system is not required in DepCSs. A state feedback control synthesis method for DepCS applying the self-recovery constraint is presented in the second part of the paper. [ABSTRACT FROM AUTHOR]

Abstract There are some biological evidences showing that the actuation system in legged animals is impulsive; it is not continuous. As opposed to continuous control/actuation, the control actions occur in specific intervals, and from the instant of one actuation until the start of the next one, passive elements guarantee the stability of the robotic system and govern its natural dynamics. In this paper, we present an analytical method for concurrent design of impulsive controller and passive elements (compliance and damper) for robotic systems; e.g., manipulators and legged-robots. To optimize the force profiles of passive elements, three different cost functions are presented which optimize the natural dynamics and energy consumption of the robot. The presented method can be applied to both cyclic and non-cyclic (explosive) tasks so as to attain energy efficient and bio-inspired motions. The method is applied to three biological models: a simulated human arm for throwing an object, a swing leg for drawing an oval, and a 3D quadruped robot for performing walking gait. Our findings in the simulation studies are in line with the hypothesis of impulsive actuation in nature and show the applicability of our method in robotics. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes a unified scheme for fault detection and isolation (FDI) that integrates model-based and multivariate statistical methods. For creating suitable models, subspace model identification is utilized together with state-observers to track the measured process operation. To describe and analyze the impact of fault conditions, the scheme utilizes input reconstruction and unknown input estimation to generate multivariate residual-based statistics. In contrast to existing work, the paper presents three industrial application studies involving sensor faults, as well as process and actuator faults which result from measured and unmeasured disturbances. [Copyright &y& Elsevier]

Highlights • The approach uses coupled actuators to stimulate the finger in two directions. • This stimulation provides a better user experience than conventional approaches. • Each individual actuator requires only a round surface with a diameter of 2.3 mm. • The lateral actuator was described and designed with a comprehensive model. • The concept of the bimodal tactile display is validated by various experiments. Abstract In this paper, a bimodal tactile display used to stimulate the mechanoreceptors is proposed. The use of tactile displays to provide tactile sensations has become the object of increasing interest in recent years. Most of these displays have only one actuator type to generate the tactile perceptions and the spatial resolution of many displays is too rough for good tactile impression. Hence, for the proposed tactile display, two types of actuators for lateral and vertical (normal) excitation are combined. The resolution of the 4 × 4 array is 2.4 mm. Due to its design concept, the presented display is easily expanded. The normal actuator is based on the reluctance principle and the lateral actuator is based on the piezoelectric effect. This contribution focuses on the design and characterization of the piezoelectric actuator. The lateral actuator is mounted on the normal actuator. This has a significant impact on the design of the piezoelectric actuator. To describe the dynamics of this actuator, a Transfer Matrix Method (TMM) Model is created. The mechanical boundary condition at the connection to the normal actuator is included utilizing discrete elements. The model is validated by experiments. Using the model, the geometry of the actuator elements is designed. For performance tests, several experiments have been carried out. The behavior of the lateral actuator has been analyzed in the two end positions of the normal actuators for different load conditions. In terms of performance, the lateral actuators achieve sufficient deflection, even under high load conditions, using imitation human skin as the contact material and with a weight of 50 g. It is shown in a subject test that the lateral actuator works well under real conditions. A measurement of the combined movement has been performed using a Micro System Analyzer (MSA-100-3D) at different frequencies. [ABSTRACT FROM AUTHOR]

This paper deals with the design and implementation of a Model Predictive Control (MPC) algorithm for an industrial recirculating cooling water system. The plant is composed of three large reservoirs, four pumping units, three cooling towers with modulating fans, and a piezometric tower. A physical model of the system has been derived from balance equations and has been validated with experimental data. Then, a nonlinear state observer has been developed to estimate unmeasured quantities, such as the water flow rates and temperatures recirculating from the utilities. Finally, an MPC algorithm has been designed by reformulating the original nonlinear system in terms of a linear time-varying one to improve the computational efficiency of the method. The presence of on/off actuators, pumps, and fans, makes the resulting optimization problem a Mixed Integer Quadratic Programming one. Extensive simulation results and comparisons with the relay-based control scheme currently implemented witness the potentialities of the proposed solution in terms of energy savings, better control, and lifetime of the equipments. The proposed MPC algorithm is currently being tested on the real plant, its very satisfactory performance confirm the results of the simulation experiments. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes a new general framework, i.e. hybrid modeling, to model dry friction systems. The proposed hybrid model has two modes (states): one models the system sliding, the second the system sticking. The model''s main advantage is the adaptation capability to observable phenomena. It is shown for the most common behaviors encountered experimentally and comparisons with other models presented in the literature are carried out. The models and methods of parameters identification of the literature are generally validated experimentally on system with sensors and actuators of high precision. This paper focuses on modeling and identifying complex mechanical system with low resolution sensors. The presented theoretical work is validated experimentally on a clutch-by-wire. [Copyright &y& Elsevier]

Abstract: Transforming feedback variables into a different co-ordinate system is a practical and effective way of simplifying controller design for multi-axis motion systems. A general transformation framework is presented in this paper for parallel-actuator systems, including those with overconstraint (i.e. with more actuators than rigid body degrees-of-freedom). Force control for the extra axes is considered, and appropriate transformations from measured actuator positions and forces to position and force variables used for control are given, although solutions are not unique. A number of heuristic techniques which are already used in the structural testing industry can be formalised as part of the new framework; examples are given in the paper. The framework also allows these techniques to be extended to new applications, particularly those with overconstraint. [Copyright &y& Elsevier]

Abstract: This paper is concerned with the design and the analysis of a semi-active suspension controller. In the recent years different kinds of semi-active control strategies, like two-state Skyhook, LQ-clipped or model-predictive control, have already been developed in the literature. In this paper, a new semi-active suspension control strategy that a priori satisfies the principal limitations of a semi-active suspension actuator (dissipative constraint and force bounds) is introduced using the tools of the linear parameter varying (LPV) theory. This new approach exhibits some interesting advantages (implementation, performance flexibility, robustness, etc.) compared to already existing methods. Both industrial criterion based evaluation and simulations on a nonlinear quarter vehicle model are performed to show the efficiency of the method and to validate the theoretical approach. [Copyright &y& Elsevier]

Abstract: Most of the proportional-integral-derivative (PID) controller tuning methods reported in literature are based on the approximate plant models (FOPDT or SOPDT models) derived from the step response of the plant. In this paper, a new method of designing PID controllers using ‘impulse response’ instead of ‘step response’ of the plant is presented. Treating the impulse response of the plant as a statistical distribution, the ‘mean’ and the ‘variance’ of the distribution are calculated and used in the calculation of PID controller parameters. Thus, the proposed method requires no approximation of the plant by any model. In this paper, a direct synthesis approach to PID controller design is proposed that makes use of Maclaurin series of the desired closed-loop transfer function, truncated up to the first three terms. PID controller parameters are synthesized to match the closed-loop response of the plant to the desired closed-loop response. Formulae for the calculation of PID controller tuning parameters are derived for the desired closed-loop response models of the types FOPDT and SOPDT. Only stable SISO systems are considered. The PID controllers tuned result in closed-loop responses very close to the desired response and perform equally well compared to other tuning methods reported in literature. [Copyright &y& Elsevier]

Abstract: This paper focuses on the problem of designing a robust fault detection scheme with group method of data handling (GMDH) neural networks. One of the main objectives is to show how to determine the structure and parameters of the neural network as well as how to estimate the modelling uncertainty of the resulting neural model. It is shown that the algorithms proposed to tackle the above tasks make it possible to obtain a suitably accurate mathematical description of the system. This description allows developing a technique of generating an adaptive threshold that permits robust fault detection. Another objective is related with an application-oriented study regarding the proposed approaches. In particular, the paper presents the results concerning the application of the techniques and algorithms for the modelling and fault detection of a valve actuator (DAMADICS benchmark). [Copyright &y& Elsevier]

Abstract: This paper concerns the problem of fault diagnosis in discrete-event systems which are represented by timed automata. The diagnostic algorithm for timed automata detects and identifies faults in the system based on the investigation whether the measured input and output sequences are consistent with the timed automaton. This diagnostic approach can be applied spontaneously to the discrete-event system since no a priori information about the initial state of the system is required. It is shown in the paper how the timed automaton which represents the DAMADICS actuator can be obtained and how the diagnostic algorithm based on the timed automaton is applied to detect and identify actuator faults. A representative diagnostic result is presented and discussed to illustrate the effectiveness of the method. [Copyright &y& Elsevier]

Abstract: This paper provides the description and presentation of the actuator benchmark used in fault diagnosis studies within the DAMADICS European Research Training Network presented in the papers of this special issue. The benchmark system is openly available, is FDI method-independent and based on an in-depth study of the phenomena that can lead to likely faults in valve actuator systems. The study uses a detailed consideration of the physical and electro-mechanical properties of an intelligent industrial actuator and includes typical engineering requirements of an actuator valve operating under challenging process conditions, e.g. provision of a set of performance indices for evaluating the results. The industrial application is focused on the sugar factory Cukrownia Lublin SA, Poland. [Copyright &y& Elsevier]

Abstract: This paper investigates the electro-mechanical behaviour of a thick, laminated actuator with piezoelectric and isotropic lamina under externally applied electric loading using a new two-dimensional computational model. The elastic core is relatively thick and thus it is modelled by Timoshenko thick-beam theory. Although the piezoelectric lamina is a beam-like layer, it is formulated via a two-dimensional model because of not only the strong electro-mechanical coupling, but also of the presence of a two-dimensional electric field. It is shown in this paper that a one-dimensional model for the piezoelectric beam-like layer is inadequate. The piezoelectric model is constructed within the scope of linear piezoelectricity. The actuation response is induced through the application of external electric voltage. Under the strong coupling of elasticity and electricity, the strain energy and work of electric potential are presented. The electro-mechanical response of the laminated Timoshenko beam is formulated and determined via a variational energy principle. Numerical examples presented illustrate convincing comparison with finite element solutions and existing published data. New numerical solutions are also presented to investigate the geometric effect on the electro-mechanical bending behaviour. [Copyright &y& Elsevier]

Buildings have in recent years been the target of a number of energy efficiency improvement strategies given that they are a major energy end-use sector in most countries. Whilst new buildings due to legislations, increasingly address sustainability and improved energy efficiency considerations, the refurbishment process of older buildings still presents a number of challenges. Advancement in Information and Communication Technology, particularly the application of low-cost Wireless Sensors and Actuators Network does however provide the opportunity to harness yet unrealized energy reduction in existing buildings. This paper presents results from an experimental study evaluating the performance and energy saving potentials of such off-the-shelve, low-cost wireless sensors and actuators network in an existing office building for occupancy detection and occupancy-driven lighting control. The study demonstrates that in addition to improved occupancy information obtainable from Wireless Sensors and Actuators Network, worthwhile savings in the energy consumption of the lighting systems can as well be achieved. [ABSTRACT FROM AUTHOR]

The development of the disc cutter replacement manipulator requires an actuator with high power density and excellent positioning precision, typically, electro-hydrostatic actuator (EHA). However, the EHA is a pump-controlled hydraulic system that has a slower response in comparison with conventional centralized hydraulics. In this paper, a position-pressure feedback control (PPFC) method is proposed to improve the system response and position accuracy. Experimental verifications showed that the suggested control method can shorten the time delay by 70.08% in the direction of positive-load movement when compared with traditional position feedback control methods, and the presented EHA can reach a precision of 0.001 mm while moving a load of 1.5 t. This enables the actuator to follow higher frequency target trajectories under heavy load with high positioning accuracy. In order to achieve better automatic control, the PPFC strategy could be combined with other controllers such as adaptive controllers. • EHA is applicable for a hydraulic manipulator for replacing the disc cutters of TBM. • Position-pressure feedback control strategy can improve the system response. • Position-pressure feedback control strategy can enhance position precision. • EHA can reach a precision of 0.001 mm while moving a load of 1.5 t. • A multi-tool-based design workflow of the EHA prototype development was summarized. [ABSTRACT FROM AUTHOR]

This paper reports on the development of a unique Digital Loudspeaker Array solution, based on Pb(Zr 0.52 ,Ti 0.48 )O 3 (PZT) thin-film actuated membranes, arranged in a matrix and which operate in a binary manner by emitting short pulses of sound pressure. Using the principle of additivity of pressures in the air, it is possible to reconstruct audible sounds. For the first time, electromechanical and acoustic characterizations were reported on 256 MEMS membranes DLA. Sounds audible as far as several meters from the loudspeaker have been generated using low-voltage. [ABSTRACT FROM AUTHOR]

In this paper, a continuous globally stable tracking control algorithm is proposed for a spacecraft in the presence of unknown actuator failure, control input saturation, uncertainty in inertial matrix and external disturbances. The design method is based on variable structure control and has the following properties: (1) fast and accurate response in the presence of bounded disturbances; (2) robust to the partial loss of actuator effectiveness; (3) explicit consideration of control input saturation; and (4) robust to uncertainty in inertial matrix. In contrast to traditional fault-tolerant control methods, the proposed controller does not require knowledge of the actuator faults and is implemented without explicit fault detection and isolation processes. In the proposed controller a single parameter is adjusted dynamically in such a way that it is possible to prove that both attitude and angular velocity errors will tend to zero asymptotically. The stability proof is based on a Lyapunov analysis and the properties of the singularity free quaternion representation of spacecraft dynamics. Results of numerical simulations state that the proposed controller is successful in achieving high attitude performance in the presence of external disturbances, actuator failures, and control input saturation. [ABSTRACT FROM AUTHOR]

Abstract: Launch control is an innovative active system which offers an appealing automatic feature for sport motorcycles. Due to the high power of the engine and to the complexity of the torque transfer dynamics driving a smooth and safe start from a standstill might be difficult for non-expert riders in some working conditions. As such, an active controller capable of safely managing the vehicle acceleration from a standing start might effectively support the rider as far as both safety and performance are concerned. To control such a maneuver, two possible actuators can be employed: the engine throttle and the clutch. This paper illustrates the analysis and the design of a clutch-based launch controller for sport motorcycles, demonstrating that it allows the accurate tracking of an acceleration set-point thanks to a dedicated clutch position controller. Experimental results are presented that demonstrate the effectiveness of the proposed approach. [Copyright &y& Elsevier]

Abstract: This paper presents a new software for teaching the most important aspects of modelling, characterization and calibration of parallel mechanisms by means of the kinematic model, the kinematic parameter identification and the control of the system actuators and sensors. This application allows the student to develop competencies such as analysis and synthesis, to solve problems, research skills and to apply their knowledge. The developed tool presents a special interest in areas such as education, industry and research, since the application interface allows the user to carry out the different steps of the calibration procedure in an easy way. Besides, only one application is necessary to perform all the procedure for data acquisition and kinematic parameter identification. Moreover, thanks to the flexibility that the developed software offers in the programming, a senior undergraduate student can modify different algorithm variables and analyze the effects that take place with these changes. This application therefore presents an important utility as a teaching tool for the learning process and analysis of the different steps in the parallel mechanism optimization. [Copyright &y& Elsevier]

Abstract: This paper discusses the use of an existing adaptive predictive controller to control some Shape Memory Alloy (SMA) linear actuators. The model consists in a truncated linear combination of Laguerre filters identified online. The controller stability is studied in details. It is proven that the tracking error is asymptotically stable under some conditions on the modelling error. Moreover, the tracking error converge toward zero for step references, even if the identified model is inaccurate. Experimental results obtained on two different kind of actuator validate the proposed control. They also show that it is robust with regard to input constraints. [Copyright &y& Elsevier]

Abstract: The automatic flatness control system applied to cold multi-roll mills for the production of metal strips has been subject of research efforts in many directions since the last 30 years. An innovative multivariable control approach for this application context is presented by means of which potential stability problems of controllers based on least mean squares are addressed. The proposed methodology decomposes the array of strip-elongation measurements produced by a conventional shape-meter into orthogonal components corresponding to the main actuator directions in order to reduce the dimensionality of the problem. Then, the control actions are computed by solving a prioritized constrained quadratic optimization problem. In this regard, the control problem is reformulated within a task-space control formalism – originally conceived in the robotics context – for which very efficient solution procedures do exist. Furthermore, in order to account for the model uncertainties that typically affects this kind of systems, the model of the process is adapted on-line by a numerically robust technique. The adaptive task-space flatness control scheme dealt with in the paper has been already commissioned in several installations having different actuator configurations and the experimental results shows its effectiveness and its easy configurability. [Copyright &y& Elsevier]

Abstract: Directe Thewireless sensor-actuator network is more and more widely used in detection area and automatic control, and the task process of network is critical. In this paper, architecture and task classification of wireless sensoractuator network are introduced, the principle of task process mechanism in the network is critically researched and analyzed and the task process in different nodes is designed. [Copyright &y& Elsevier]

Abstract: In most maglev (magnetic levitation) systems, redundant electromagnetic actuators are usually used to increase the stability and robustness of the levitation motion. However, the obvious interactions generate between the redundant actuators and other general electromagnetic actuators. In this paper, a new and efficient redundant levitation control strategy is developed to overcome the interactions in this maglev system. In the strategy, some separate general controllers are designed for all general actuators, and then some special controllers are used to real-time track the electromagnetic forces of all general actuators, and accordingly they create control signal for the redundant actuators to counteract the interactions among general actuators and redundant actuators. To further illustrate the strategy, a novel redundant actuation maglev system is then demonstrated, and a simplified expression of the redundant control strategy is investigated for the maglev system. The experimental results show that the redundant levitation controller successfully removes the interactions between redundant actuator and general actuators, and the redundant levitation controller maintains good robustness under disturbance. [Copyright &y& Elsevier]

Abstract: Shape memory alloys (SMA) are being more frequently integrated into engineering applications. These materials with their shape memory effect enable the simplification of mechanisms and the reduction in size of actuators. SMA parts can easily be activated by Joule effect but their modeling and consequently their control remains difficult. It is principally due to their non-linear hysteretic thermomechanical behavior. Most of successful control strategies applied to SMA actuators are not often suitable for industrial applications: they are particularly heavy and use the Preisach model or neural networks to model the hysteretic behavior of these materials; this kind of model is difficult to identify and to use in real time. This paper deals with an application of the new framework of model-free control (MFC) of an SMA-spring based actuator. This control strategy relies on new results for fast derivative estimation of noisy signals. Their main advantages are: its simplicity and its robustness. Experimental results and comparisons with PI control are presented that demonstrate the efficiency of this new control strategy. [Copyright &y& Elsevier]

Abstract: This paper is concerned with modeling, analysis, and control of the cable-supporting system including actuator dynamics for the next generation large spherical radio telescope. According to its 50-m scaled model, to begin with, the dynamic formulations of the electromechanical coupling system including servomechanism dynamics and parabolic curve of the long-span cable sag effects are established; at the same time the relationship among cable force, cable end displacement and cable length variation is obtained by utilizing parabolic equation, and the dynamic modeling for control can be justified by the numerical example. In addition, taking account of the characteristics of nonlinearity, slow time-variant and multivariable coupling, a fuzzy control plus proportional-integral control method is utilized to control the wind-induced vibration of the cable-supporting system. Finally, simulation results from the 50-m scaled model control system, regarding the wind-induced vibration control of the cable-supporting structure in stationary position and the tracking control of the cable-supporting system, show the satisfactory performance of the proposed control scheme as compared with a discrete-time automatic disturbances rejection controller in the presence of internal model uncertainties in both the cable-supporting mechanism and servomechanism dynamics and external disturbances. [Copyright &y& Elsevier]

Abstract: This paper considers observer-based actuator fault detection and reconstruction problems for uncertain nonlinear systems. Based on a kind of full-order observer which is robust to disturbances but sensitive to actuator faults, a single detection observer is constructed to produce a residual which can be used to alarm the occurrence of the actuator faults when at least one actuator fault occurs indeed. The full-order observer is adaptive one because an adaptation law which can adjust the Lipschitz constant of Lipschitz term is introduced. For this reason, the Lipschitz constant can be unknown in our design. After this, a kind of reduced-order observer is developed by choosing a special observer gain matrix. Based on the reduced-order observer, we provide a kind of unknown information estimating method which can be used to not only reconstruct the actuator faults but also estimate the disturbances of the system. In simulation, a real model of the seventh-order aircraft is used to illustrate the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

Abstract: For the problem of automatic flatness control (AFC) in cold tandem mills this paper proposes control techniques based on quadratic optimization and delay compensation. Three different strategies are presented and compared: a centralized solution based on a global quadratic programming (QP) problem that decides the commands to all the actuators, and two decentralized solutions where each actuator command is optimized locally. All schemes are based on a global exchange of information about the commands generated at the previous time step at each stand to compensate for the numerous delays present in the mill. Control algorithms are tested in simulation considering a tandem mill with five stands as a benchmark, and results are shown to demonstrate the performance of the proposed schemes. [Copyright &y& Elsevier]

Abstract: In this paper a heuristic design strategy for stabilizing the satellite attitude has been proposed. It is assumed that the satellite is actuated by a set of mutually perpendicular magnetic coils. Using well-known Lyapunov direct stability method it is shown that the proposed controller causes to a global asymptotic stable system for all near polar orbits. The design procedure is based on analyzing of the conceptual effects of magnetic coils on the satellite attitude motion. Considering these effects lead to some intuitive results which determine the global stabilizing control law. The performance and robustness of the designed controller against actuators saturation and quantization error have been verified using a real-time-hardware–software in-loop (RTHSIL) simulation results. These results show that the global stability can be achieved although some disturbances and restrictions exist. This stabilizing controller can be simply combined with a linear explicit model predictive controller (EMPC) to achieve a full three-axis control law. [Copyright &y& Elsevier]

Abstract: The wireless sensor/actuator networks (WSANs) can be used for spatially distributed control systems. With smart sensors and actuators, the WSANs are able to not only sense the control system states and report measurements, but also perform control and actuation. This paper investigates WSANs on their ability of control. A centralized controller is introduced into WSANs to make up closed-loop control systems, in which control decisions are made based on global network-wide information. A model of the control and communication over WSANs is made theoretically, based on which we achieved an optimal control method. It is demonstrated by simulations that the control method proposed could stabilize the control system quickly. [Copyright &y& Elsevier]

Abstract: This paper presents a robust adaptive fuzzy control algorithm for controlling unknown chaotic systems. The control approach encompasses a fuzzy system and a robust controller. The fuzzy system is designed to mimic an ideal controller, based on sliding-mode control. The robust controller is designed to compensate for the difference between the fuzzy controller and the ideal controller. The parameters of the fuzzy system, as well as uncertainty bound of the robust controller, are tuned adaptively. The adaptive laws are derived in the Lyapunov sense to guarantee the stability of the controlled system. Numerical simulations show the effectiveness of the proposed approach. [Copyright &y& Elsevier]

Abstract: The infrastructure associated with an automated irrigation channel contains a large number of actuators (electro-mechanical gates) and water level and gate position sensors. Actuator and sensor faults happen from time to time, and they will lead to loss of water and reduced service to farmers unless corrective action is taken. In this paper strategies for dealing with such faults are presented. Sensor faults are dealt with by estimating the value of the signal measured by the faulty sensor and using the estimated signal as input to the controllers. An actuator fault necessitates a relaxation of the control objectives, and it requires a reconfiguration of the controller. The developed methods were successfully tested on an operational irrigation channel. Despite the faults, very good control performance was achieved, and there were no disruptions to the operation of the channel. [Copyright &y& Elsevier]

Abstract: This paper investigates the application of a piezoelectric actuator to control deformation of thin arbitrary lay-up composite laminates. A theoretical model based on Rayleigh–Ritz principle is developed to predict laminate cured shape and the effect of piezoelectric actuator layer. Several stacking sequences are studied using the model. When applied to pure composite laminates it is observed that cured shape of near-unidirectional laminates is always saddle. When applied to arbitrary lay-up piezo-composite laminates, it is found that the principal direction of the laminates can change with electric field. This is one unique feature of such type of laminates. A new FEA technique is proposed to deal with the multiple solution issue and obtain the stable solution more precisely. [Copyright &y& Elsevier]

Abstract: In this paper, we present a dual actuator logging disk architecture to minimize write access latencies. We reduce small synchronous write latency using the notion of logging writes, i.e. writing to free sectors near the current disk head location. However, we show through analytic models and simulations that logging writes by itself is not sufficient to reduce write access latencies, particularly in environments with writes to new data and intermixed reads and writes. Therefore, we augment the logging write method with the addition of a second disk actuator. Our models and simulations show that the addition of the second actuator offers significant performance benefits over a normal disk over a wide range of disk access patterns, and comparisons to strictly logging disk architectures show advantages over a range of disk access patterns. [Copyright &y& Elsevier]

Abstract: This paper presents an experimental implementation of a shared vehicle longitudinal controller at low speed. The main objective is the increase of traffic capacity while improving safety and comfort. The longitudinal control method used is based on a second order sliding mode technique. The central controller is based on the management of inter-vehicular spacing in relation to vehicle speed. Results are presented both by simulation and by use of an experimental process with a vehicle prototype which is equipped with the required sensors and actuators. A number of scenarios are tested under usual traffic conditions such as stop-and-go, stopping at obstacles and car-following with merging/overtaking. Finally, the positive impact of such a system is given in terms of traffic capacity enhancement and collision gravity reduction. [Copyright &y& Elsevier]

Abstract: Moving towards the More Electric Aircraft, a hybrid actuator configuration, in which an electromechanical actuator (EMA) and an electrohydraulic servoactuator (EHSA) operate on the same control surface, provides an opportunity to introduce electromechanical actuators into primary flight controls. Besides the operation in active/passive or active/active mode, an “active/no-load” mode is promising. In this mode the EMA is controlled such that it actively follows the movement of the control surface without carrying external air loads, thereby reducing power dissipation compared to active/active mode and failure transients compared to active/passive mode. However, force fighting will occur if both actuators are actively controlled. In this paper, control concepts for a hybrid configuration, extending the original actuator control loops, are presented, enabling active/active as well as active/no-load operation. Nonlinear as well as linear models for an EMA, an EHSA, and a control surface structure are derived from technical data for an airworthy EHSA and combined to a model of the hybrid configuration. These models are used for matching of actuator dynamics and simulation of the developed control laws. For active/active mode, maximum force fighting between the actuators is reduced from about 500% to 7% of the stall load. For active/no-load mode, a force control loop is added to the EMA control, causing the EMA to follow movements of the control surface such that the external loads on the EMA are zero in steady-state. Force fighting is reduced to 30% of the stall load. [Copyright &y& Elsevier]

Abstract: Photostrictive materials produce mechanical strain when irradiated by ultraviolet light, thus may be used in wireless remote control of smart microstructures. This paper presents an investigation into modelling and static shape control of beams with nonlinear photostrictive actuators. Governing equations of beams bonded with photostrictive actuator patches are derived to study the interaction between the photostrictive actuators and the host beams. An analytical solution method is presented to solve the governing equations of the beams with discretely distributed photostrictive actuators. An iterative procedure is developed to find optimal light intensities in photostrictive actuators that best match the actuated shape to the desired one. An example is given to illustrate the model and shape control of a beam with PLZT actuators. [Copyright &y& Elsevier]

Abstract: The paper discusses the concept of using a piezoceramic actuator bonded to one side of a two-layer unsymmetric cross-ply [0/90]T laminate to provide the moments necessary to snap the laminate from one stable equilibrium shape to another. This concept could be applied to the morphing of structures. A model of this concept, which is based on the Rayleigh–Ritz technique and the use of energy and variational methods, is developed. The experimental phase of the study is discussed, including the measurement of the voltage level needed to snap the laminate. The voltage measurements and shapes are compared with predictions of the models and the agreement between measurements and the predictions are reasonable, both qualitatively and quantitatively. Suggestions for future activities are presented. [Copyright &y& Elsevier]

Abstract: Optimal induced strain actuator sizes for an L-shaped laminated frame are determined under deterministic and uncertain loads with the objective of minimizing the tip deflection. The bending moments generated by the induced strain actuators control the deflection in order to minimize the maximum deflection. The frame is elastically restrained at the tip point and is subjected to a tip load which is specified for the deterministic case and lies in an uncertainty domain in the uncertain case. The specific uncertain loading studied in the present paper involves a load of given magnitude but of unknown direction which should be determined to induce the highest tip deflection caused by the least favorable loading. The effects of the elastic restraints and actuator locations on the deflection behaviour are investigated. It is shown that the optimal actuator size depends on the magnitude of the moments provided by the actuators. Moreover, it is observed that a deterministic design under an uncertain load leads to excessive deflections indicating the necessity of a robust design. [Copyright &y& Elsevier]

Abstract: Advanced reinforced composite structures incorporating piezoelectric sensors and actuators are increasingly becoming important due to the development of smart structures. These structures offer potential benefits in a wide range of engineering applications such as vibration and noise suppression, shape control and precision positioning. This paper presents a finite element formulation based on the classical laminated plate theory for laminated structures with integrated piezoelectric layers or patches, acting as sensors and actuators. The finite element model is a single layer triangular nonconforming plate/shell element with 18 degrees of freedom for the generalized displacements, and one additional electrical potential degree of freedom for each surface bonded piezoelectric element layer or patch. The control is initialized through a previous optimization of the core of the laminated structure, in order to minimize the vibration amplitude and maximize the first natural frequency. Also the optimization of the patches position is performed to maximize the piezoelectric actuators efficiency. The simulated annealing algorithm is used for these purposes. To achieve a mechanism of active control of the structure dynamic response, a feedback control algorithm is used, coupling the sensor and active piezoelectric layers or patches, and to calculate the dynamic response of the laminated structures the Newmark method is considered. The model is applied in the optimization of an illustrative adaptive laminated plate case. The influence of the position and number of piezoelectric patches, as well as the control gain, are investigated and the results are presented and discussed. [Copyright &y& Elsevier]

Abstract: This paper presents the application to the DAMADICS benchmark fault detection problem of a model-free fault detection technique based on the use of a specific spectral analysis tool, namely, the Squared Coherency Functions (SCFs). The detection of a fault is achieved by on-line monitoring the estimate of the squared coherency function, which is sensitive to the occurrence of significative changes in the plant dynamics. The alarm threshold are based on the estimates of the confidence intervals of the SCF. Results on both simulation and real data of the DAMADICS benchmark (which is developed to approximate the industrial process in a sugar factory located in Lublin, Poland) are outlined. [Copyright &y& Elsevier]

Abstract: The paper discusses the problems of fault distinguishability in case of a multiple-valued evaluation of fault symptoms. Definitions of conditional and unconditional fault distinguishability are introduced to make allowance for assessment of quality of fault isolation approaches. Definitions of the sensitivity of fault distinguishability and sensitivity of fault detectability on the set of available process variables are formulated. Based on an example, it is demonstrated that distinguishability factors can be improved by application of multiple-valued evaluation of symptoms instead of binary ones. Fault distinguishability and detectability factors are examined on the example of actuation system. Practical hints for the actuator designers and users are given. [Copyright &y& Elsevier]

Abstract: In this paper a method for fault-tolerant control in dynamic systems is presented. The proposed approach is composed of two stages. The first stage is the detection and isolation of the failed component using a directional filter designed under a particular eigenstructure assignment. The second stage is represented by the reconfiguration mechanism which makes possible the compensation of the fault effects. This approach was applied to the web tension control of winding machine and gave good results for actuator fault accommodation. [Copyright &y& Elsevier]

Abstract: Side forces on slender bodies of revolution at medium to high angles of attack (AOA>30°) has been known from a large number of investigations. Asymmetric vortex pairs over a slender body are believed to be the principle cause of the side forces. Under some flight conditions, this side force may be as large as the normal force acting on the slender body. In this paper, experimental results are presented for side force control on a cone-cylinder slender body by using microfabricated balloon actuators. The micro balloon actuators are made of polydimethylsiloxane (PDMS) elastomer by using micro molding techniques. They can be packaged on curve surfaces of a cone-cylinder slender body. As actuator is actuated, the micro balloon actuator inflates about 1.2mm vertically, which is about 2.4% of the cylinder diameter D (=50mm) of the cone-cylinder slender body. Micro balloon actuators are actuated at different roll angles of a cone-cylinder slender body. Aerodynamic force measurement results indicate the effects of micro balloon actuators vary at different actuation locations on the cone-cylinder slender body. The side forces can be significantly reduced if the actuators are actuated in the weak vortex side (the side corresponding to the asymmetric vortex which is far from the surface) and actuation angles are located at about 50–60° (the actuation angle here is measured from stagnation line of the incidence plane toward weak vortex side direction). Significant changes are noticed from the surface pressure, as well as leeside vortex flow field, measurement. Micro balloon actuators change nose shapes of the slender body which decide adverse-pressure-gradient values and directly influence the origin of the separation lines and characteristics of the separated vortices over the leeside surface. [Copyright &y& Elsevier]

Abstract: In this paper an adaptive control is developed, based on an estimation of the disturbing torque transmitted inside the dead zone of an electromechanical system. Disturbing backlash torque is modelled by a continuous and derivable mathematical function describing an opposite of sigmoid function. Then, nonlinear observer of dead zone amplitude is synthesized. Simulation and experimental tests applied to an electromechanical actuator are given to support the theoretical demonstrations. [Copyright &y& Elsevier]

Abstract: This paper illustrates the effect of stiction in actuators on closed loop performance and the importance of techniques, to be incorporated in the monitoring system, for automatic detection of the onset of this phenomenon. Three different techniques are compared on the basis of simulation by means of stiction models and it is shown how loop variables are affected by stiction parameters and by process characteristics. A major finding is that every technique has an uncertainty region where no decision can be taken in the absence of further information about the process. The application on industrial data, recorded on loops affected by stiction during routine plant operation, allows to confirm this result and to assess relative efficiency of the techniques. A simple test to be performed directly on the plant is also proposed to solve the remaining uncertain cases. [Copyright &y& Elsevier]

Abstract: A monolithic and symmetric structure is good for reducing mechanical noise, such as thermal and compliant errors. Design and analysis of six-degree freedom ultra precision positioning system with compliant mechanism is described in this paper. An inclined bridge displacement amplifier is developed to achieve out-of-plane motions. A mechanism to amplify displacement is used to overcome short travel range of piezoelectric actuator. Mathematical model is derived using Castigliano''s second theorem to express the relation between displacement and force applied at the end point of flexure hinge. Using vector analysis, a relative displacement of flexure hinge is calculated. A stiffness matrix of proposed system is derived using least action principle. Three-dimensional modeling and simulation of the proposed system with flexure hinge mechanism is carried out to compare the results with that obtained by stiffness matrix which is derived by hand. Translational differences of two methods are 28% in x-axis and 29% in y-axis and rotational differences are17% in x-axis, 23% in y-axis and 13% in z-axis. [Copyright &y& Elsevier]

This paper proposes a novel scheme of sensor/actuator fault detection and isolation (FDI) for multivariate dynamic systems in the presence of process uncertainties, including model-plant-mismatch and process disturbances. Given an estimated model that can be biased from the true one, the primary residual vector (PRV), for detecting faults in output sensors, can be made completely insensitive to process uncertainties under certain conditions. For detecting faults in actuators, the PRV can be made almost insensitive to the process uncertainties. Numerical and experimental examples justify the effectiveness of the proposed scheme, where comparison with an existing robust FDI scheme is conducted. [Copyright &y& Elsevier]