Abstract
Abstract This thesis presents new design schemes for sliding-mode control (SMC) with the aim that system robustness can be adjusted according to the designer’s specifications. The main design idea proposed in this thesis is that of clustering the closed-loop poles within a predefined region instead of fixed locations for the robust performance in sliding-mode to be adjustable. Firstly, a novel global sliding-mode control scheme with adjustable robustness (GSMCAR) is proposed, which offers a switching function together with nominal system dynamics to weigh the contribution between SMC and state feedback control such that the maximum control effort and the chattering level can be reduced effectively. With given bounds of perturbation, the closed-loop poles can be located within a predefined region in the left-half s-plane. Furthermore, a Jury’s test is utilized to determine the weight of SMC in which the desired regions are defined as a circular disk. Since the switching function is equal to zero initially and thereafter, the adjustable robustness can be guaranteed during the entire response. Subsequently, an integral global sliding-mode control (IGSMC) scheme is proposed to further improve the steady state performance of the GSMCAR scheme. This scheme offers an integral action on control effort so that the steady state error can be minimized. The robust performance in sliding-mode can be adjusted as well. Lastly, a global sliding-mode control with bound input (GSMCBI) scheme is proposed to deal with the tracking control problem of a system with bounded input constrain, in which a moving sliding function is developed. In order to investigate the feasibility of the proposed schemes, a linear variable reluctance motor drive system with a hysteresis current-controlled inverter is established. Both the simulation and the experimental studies further demonstrate their effectiveness.