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In this paper, stabilization is presented for a networked control system with actuator saturation and network-induced delays. A method is exploited at updating steps of control signal rather than sampling steps in the networked control system under actuator saturation. A network-based controller is designed under the limitation of actuator saturation. With a cone complementary linearization approach, a presented scheme is also used to estimate the domain of attraction for the networked control system. A numerical simulation is provided to show the effectiveness and correctness of the method in this paper. [ABSTRACT FROM AUTHOR]

Shape-Memory-Alloys (SMA) are suited for miniaturized drives since they possess a high specific workload and scalability. However, most SMA drives still require guidance to realize stiffness. But, there is a design approach for actuators which realize both. Here, the stiffness in the non-moving directions is achieved by the arrangement of the SMA as wire robot. This paper presents a general description of such actuators. Based on that the design of such actuators is formulated as a mathematical optimization algorithm providing a correlation between the variables for design and specification. In order to evaluate this approach, a rotary and a linear actuator are designed and experimentally investigated. [ABSTRACT FROM AUTHOR]

Abstract: Actuators were developed using activated and non-activated multi-walled carbon nanotube (MWCNT)–ionic liquid (IL) gel electrodes and compared to a single-walled carbon nanotube (SWCNT)-based actuator with respect to the electrochemical and electromechanical properties. The activated MWCNT–COOH/polymer actuator surpassed the SWCNT/polymer actuator in terms of the generated strain. [Copyright &y& Elsevier]

Abstract: This contribution deals with an energy based controller design for an under-actuated mechanical system with a hydraulic piston actuator. In particular, the example consists of a single acting piston actuator and a rigid mass between two springs. For the resulting system a static feedback control is designed based on energy consideration. Since the control algorithm requires the velocities, which are not measurable in this application, it is extended by a reduced observer. In addition, the stability of the desired equilibrium of the closed loop system is proven and the results are illustrated by simulation. [Copyright &y& Elsevier]

Abstract: An autonomous catamaran, based on a modified Prindle-19 day-sailing catamaran and fitted with several sensors and actuators was built to test the viability of GPS-based system identification for precision control. Using an electric trolling motor for propulsion, and lead ballast to match all-up weight, several system identification passes were performed to excite system modes and model the dynamic response. The identification process used the Observer Kalman IDentification (OKID) method for identifying a linear time invariant plant model and associated pseudo-Kalman filter. System identification input was generated using a human pilot driving the catamaran on roughly straight line passes. A fourth order discrete time model was generated from the data, and showed excellent prediction results. Using these models, linear quadratic Gaussian (LQG) controllers were designed and tested with the electric trolling motor. These controllers demonstrated excellent line-tracking performance, with error standard deviations of less than 0.15m. The wing-sail propulsion system was fitted, and these same controllers re-tested with the wing providing all propulsive thrust. Line-following performance and disturbance rejection were excellent, with the cross-track error standard deviations of approximately 0.30m, in spite of wind speed variations of over 50% of nominal value. [Copyright &y& Elsevier]

Abstract: This paper presents a systematical design and characteristic evaluation approach for constructing a one-wheeled actuator driven by one piezoelectric element. Such an actuator is of quite simple construction and equipped with a beam and one movable piezodisc, thereby giving a direct drive which can be particularly useful in applications for micro motion devices. A theoretical model of the actuator is derived based on the lateral elliptical motion, in order to predict driving frequencies of the actuator. Finite element analysis (FEA) modal patterns are employed to investigate dynamic vibration modes, driving frequencies and characteristics of the actuator. Experimental results are conducted for illustration of validity of the proposed design and analysis method, and for verification of characteristics of the one-wheeled actuator. [Copyright &y& Elsevier]

Abstract: Improving positioning ability of electroactive polymer actuators typified by polypyrrole (PPy) through feedback control of their position has been considered. The actuators operate in air, as opposed to their predecessors. One of the problems associated with the actuators is the forward relaxation/creep or drift, which occurs after the full reduction and oxidation processes are completed. A high-resolution laser displacement sensor was used to detect the position of the cantilever-type polymer actuators and the classical, yet effective, Proportional, Integral and Derivative (PID) control method has been employed to generate the appropriate control input in order to make sure that no drift occurs in the user-specified position of the actuators. A set of experimental results with and without feedbacking the position data are presented to demonstrate the efficacy of the control method for improving the positioning ability and the speed of response. The rise time is reduced by more than 500 times and the position tracking error is less than 10% for a time-varying user-specified position command. [Copyright &y& Elsevier]

Abstract: We have fabricated and characterized a reciprocating poly(methylmetacrylate) (PMMA) ball-valve micropump actuated with a miniaturized cylindrical electromagnetic circuit. By finite element calculations, we have optimized the structure of the electromagnet that actuates a rare-earth permanent magnet embedded in a poly(dimethylsiloxane) (PDMS) pumping membrane. Powder blasting and conventional micromachining techniques are used for micropatterning the PMMA layers forming the microfluidic circuit. The self-priming ball-valve micropump exhibits a backpressure up to 35kPa; water is pumped at a flow rate as high as 6.0mL/min for a 2W electromagnetic actuation power at the resonant frequency of 20Hz. The actuation frequency-dependent flow rate is in excellent agreement with a damped oscillator model. [Copyright &y& Elsevier]

Abstract: This paper presents the topology optimized design procedure and fabrication of electrothermal polysilicon microgrippers for nanomanipulation purposes. Performance of the optimized microactuators is compared with a conventional three-beam microactuator design through finite element analysis. The accuracy of the finite element model is verified by comparison of simulated and measured displacement vs. bias voltage curves. A considerable improvement in the mechanical stiffness is indicated by AFM force measurements, being 9 times higher compared to the conventional three-beam actuator. [Copyright &y& Elsevier]

Abstract: This paper describes experiments with the surface resistance of IPMC actuators and sensors. We measure the surface resistance of samples working as sensors or as a voltage driven actuators, as well as when insulated. The results show that in all cases the surface resistance of a sample is highly correlated to material curvature. Based on these observations we present an equivalent circuit, with variable resistors representing surface resistance, that models IPMC materials. Our simulations with SPICE show that the equivalent circuit closely models the actual behaviour of IPMC sensors and actuators. We show that since the IPMC model works as a delay line with changing resistors, the curvature of the IPMC sample at a given point depends on the surface resistance. This, in turn, affects further bending of the sample. The modified equivalent circuit also explains the hysteresis of IPMC actuators as the signals along the surface are delayed. [Copyright &y& Elsevier]

Abstract: The present study describes a comprehensive investigation performed to study the effects of piezoceramic materials on the augmented damping of vibrating piezo-composite beams. The augmented active damping is obtained by using an actuator and a sensor made of piezoceramic materials, acting in a ‘closed-loop’. Transferring the accumulated voltage on the sensor layer to the piezoelectric actuator layer causes the beam to actively damp-out its vibrations. The voltage transferred from the sensor to the actuator has to be amplified through a feedback gain. An exact mathematical model based on a first order shear deformation theory (FSDT) was developed and described in order to study the effect of all four possible piezoelectric ‘closed-loop’ combinations (EE, SS, ES and SE). The first two combinations use only one piezoelectric mechanism, extension or shear, as both sensors and actuators, while the other two, use combined piezoelectric mechanisms, extension and shear. Using the present model, both natural and damped vibrations were calculated. A comprehensive parametric investigation was performed to study the required feedback gain, G, for each piezoelectric combination, and the effect of piezoelectric materials on damping higher frequencies. [Copyright &y& Elsevier]

Abstract: In this work we present a bi-stable diamond micro-bridge with a centre operating contact, which can be used in various fields of application. The actuator is based on the thermal bi-metal actuation principle, switching a double anchored cantilever beam between two bi-stable positions as described previously [P. Schmid, F. J. Hernandez-Guillen and E. Kohn, Diamond and Related Materials, 12 (2003), pp. 418–421]. The actuator device is composed of two parts: (a) the beam actuator (which enables a bi-stable vertical movement of an operating contact) with frame and pillars, and (b) the base plate, which contains the contact base. The bi-metal actuator principle allows the generation of large forces acting onto the base, since the base-plate technology is independent from that of the actuator. Hybrid integration of this system offers applications in various fields. Several examples are proposed and described. [Copyright &y& Elsevier]