In this paper a novel Active Vibration Control (AVC) strategy based on fractional-order calculus is developed. A fractional-order Positive Position Feedback (PPF) compensator is proposed to overcome the limitations of the commonly used integer-order PPF such as: frequency spillover, amplitude amplification in the quasi-static region of the closed-loop response, and difficult tuning in multi-mode control. Tuning parameters of the controller are obtained by optimizing both magnitude and phase response of the controlled plant. Results are shown by comparing performances of the standard integer-order PPF and the optimized fractional-order PPF, both on a simple 1-DOF plant and on measured frequency response data from a rectangular carbon fibre composite plate.

This paper presents a simple and systematic approach to design second order sliding mode controller for buck converters. The second order sliding mode control U+0028 SOSMC U+0029 based on twisting algorithm has been implemented to control buck switch mode converter. The idea behind this strategy is to suppress chattering and maintain robustness and finite time convergence properties of the output voltage error to the equilibrium point under the load variations and parametric uncertainties. In addition, the influence of the twisting algorithm on the performance of closed-loop system is investigated and compared with other algorithms of first order sliding mode control such as adaptive sliding mode control U+0028 ASMC U+0029, nonsingular terminal sliding mode control U+0028 NTSMC U+0029. In comparative evaluation, the transient response of the output voltage with the step change in the load and the start-up response of the output voltage with the step change in the input voltage of buck converter were compared. Experimental results were obtained from a hardware setup constructed in laboratory. Finally, for all of the surveyed control methods, the theoretical considerations, numerical simulations, and experimental measurements from a laboratory prototype are compared for different operating points. It is shown that the proposed twisting method presents an improvement in steady state error and settling time of output voltage during load changes.

A hollow microcantilever is used instead of a conventional microcantilever to dispense and aspirate liquids in the femto-litre (10^-15 L) volume range in an atomic force microscope (AFM) setup. The inherent force sensing capability of the cantilever is used to monitor the fluid manipulation in-situ. At this small scale, parameters like: surface energy, evaporation, viscosity and temperature become important for controlled manipulation. In a conventional AFM, these parameters are usually not taken into consideration as feedback parameters. In the present work, we report initial experimental results on the dosing process and an analytical dynamic model of the process. The model is based on the liquid bridge between the cantilever tip and the substrate, which can describe the dosing process with variance accounted for (VAF) larger than 90%. We aim to use this model and implement a control system for precise dispensing and aspiration.

This paper investigates an improved scheme of set-point regulator using a reset control terminology in exhaust gas recirculation system of gasoline engine. The presented control structure is based on a first-order reset element (FORE) that can be applied to linear system. Using this structure, the asymptotic rejection of disturbances occurring on the plant’s input can be obtained. At the end, the conventional FORE is modified with the concept of fractional calculus. Such an ideology can be resulted in possessing some flexibility in design as well as presenting much better dynamic response in term of overshoot and rise time.

A cost-effective position measurement system based on optical mouse sensors is presented in this work. The system is intended to be used in a planar positioning stage for microscopy applications and as such, has strict resolution, accuracy, repeatability, and sensitivity requirements. Three techniques which improve the measurement system's performance in the context of these requirements are proposed; namely, an optical magnification of the image projected onto the mouse sensor, a periodic homing procedure to reset the error buildup, and a compensation of the undesired dynamics caused by filters implemented in the mouse sensor chip.

This paper presents an improved scheme of fractional PID controller applied to the torque control problem of spark ignition (SI) engines. The objectives are to produce a minimum torque tracking error while obtaining fewer fuel consumption during the process of combustion. This is then resulted to provide a fast and monotonic air flow response into the engine cylinders by adjusting the throttle and EGR plate angle and the cam timing. This consideration also pushes the engine to work in its safe operational condition, avoiding from both knocking and misfiring damage. Afterwards, a preliminary investigation to obtain maximum efficiency is conducted on the idea of exploiting Genetic Algorithm that is commonly used in parallel optimization of controller coefficients. Eventually, simulation results illustrate effectiveness of proposed scheme in comparison with classical PID controller method.

Piezo steppers or piezo-walk actuators are attractive primararily because of their high accuracy and long range of motion combined in a single actuator. They are commonly used devices for short stroke scanners where significant range of motion is desired with good displacement resolution. A major performance limiting factor in these actuators is that, during stepping, large disturbances and vibrations are induced due to hammering action of the clamp piezolegs leading to development of stepping errors. In order to reduce these stepping errors, a good control scheme needs to be developed to drive the clamp piezo legs. It is of great advantage to use the self sensing property of the piezolegs to get a feedback signal because it prevents design changes to the actuator and saves valuable space. In this research, the self-sensing property of the piezolegs is applied to detect contact. This paper presents a novel application of the self-sensing contact detection method and a successful implementation inside the piezo-stepper to detect contact of the piezolegs with the driving rod.