This paper addresses the problem of the fractional sliding mode control (FSMC) for a MEMS optical switch. The proposed scheme utilizes a fractional sliding surface to describe dynamic behavior of the system in the sliding mode stage. After a comparison with the classical integer-order counterpart, it is seen that the control system with the proposed sliding surface displays better transient performance. The claims are justified through a set of simulations and the results obtained are found promising. Overall, the contribution of this paper is to demonstrate that the response of the system under control is significantly better for the fractional-order differentiation exploited in the sliding surface design stage than that for the classical integer-order one, under the same conditions. تفاصيل المقالة

In this paper, a robust PID control scheme is proposed for Micro-Electro-Mechanical-Systems (MEMS) optical switches. The proposed approach is designed in a way which solves two challenging and important problems. The first one is successful reference tracking and the second is mitigating the system nonlinearities. The overall system composed of nonlinear MEMS dynamics and the PID controller is proven to be uniformly-ultimately bounded (UUB) stable in agreement with Lyapunov’s direct method in any finite region of the state space. Since the unmodeled but bounded dynamics of the system is systematically encapsulated in the system model, the only influence that this imposes on the stability is the respective bounds on the controller gains. The controller design strategy is simple and practicable with low computation burden which makes it easy to apply for control of MEMS optical switch. It also forms a constructive and conservative algorithm for suitable choice of gains in PID controller. The effectiveness of the proposed control law is verified through simulations in MATLAB/SIMULINK. It is shown that the proposed control law ensures robust stability and performance despite the modeling uncertainties. تفاصيل المقالة

This paper presents a robust fractional order controller for flexible-joint electrically driven robots under imperfect transformation of control space. The proposed approach is free from manipulator dynamics, thus free from problems associated with torque control strategy in the design and implementation. As a result, the proposed controller is simple, fast response and superior to the torque control approaches. It can guarantee robustness of control system to both structured and unstructured uncertainties associated with robot dynamics. The control method is verified by stability analysis. Simulation results on a two-link actuated flexible-joint robot show the effectiveness of the proposed control approach. تفاصيل المقالة