A Chattering Free Discrete-Time Global Sliding Mode Controller for Optoelectronic Tracking System

Abstract

Aiming at the uncertainties including parameter variations and external disturbances in optoelectronic tracking system, a discrete-time global sliding mode controller (DGSMC) is proposed. By the design of nonlinear switching function, the initial state of control system is set on the switching surface. An adaptive discrete-time reaching law is introduced to suppress the high-frequency chattering at control input, and a linear extrapolation method is employed to estimate the unknown uncertainties and commands. The global reachability for sliding mode and the chattering-free property are proven by means of mathematical derivation. Numerical simulation presents that the proposed DGSMC scheme not only ensures strong robustness against system uncertainties and small tracking error, but also suppresses the high-frequency chattering at control input effectively, compared with the SMC scheme using conventional discrete-time reaching law.

Research of Compound Control for DC Motor System Based on Global Sliding Mode Disturbance Observer

“…From Figure 1, if the equivalent disturbance of DC motor system is estimated by some estimation methods, the same amount of compensation to control input will effectively inhibit the impact of equivalent disturbances on the control system. Based on this control thought, we will design a GSMDO for DC motor system according to model (2).…”

“…Moreover, the power/mass ratio has been greatly increased. Therefore, DC motor has been widely used in various servo devices including flight simulator [1], optoelectronic tracking platform [2], and missile electromechanical actuator [3]. Meanwhile, the requirement of the process environment on the performances of DC motor system is increasing.…”

A Reference Trajectory Based Discrete Time Sliding Mode Control Strategy

“…Their idea assumes selecting a sliding hyperplane (Luis-Delgado et al, 2017), which ensures stable steady state behaviour, and describing the sliding variable with a function, which drives the representative point to the chosen plane. Several researchers have worked to improve Gao's control strategy (Bartoszewicz, 1996;Ren et al, 2013;Veselic et al, 2010;Qu et al, 2014) and numerous new reaching laws have been proposed (Bartoszewicz,1998;Leśniewski and Bartoszewicz, 2015;Bartoszewicz and Leśniewski, 2016;Latosiński, 2017;Latosiński and Bartoszewicz, 2018;Monsees and Sherpen, 2001;Vivekanandan et al, 2008;Golo and Milosavljewic, 2000;Niu et al, 2010;Ma et al, 2017;Zhang, 2016;Chakrabarty and Bandyopadhyay, 2015; 2016; Chakrabarty and Bartoszewicz 2016) ever since. In our work we propose a new, reference trajectory following sliding mode control strategy.…”

A general switching type reaching law for discrete time sliding mode control systems

“…In [13] it is extended by a disturbance compensator, which is designed under the assumption of limited rate of change of the disturbance. In [12] the authors modified the reaching law proposed in [8] by making the constant switching term a function of the absolute value of the sliding variable. In [16] the authors apply a reaching law in which there is no proportional term, but the switching term assumes a large value when the distance from the hyperplane is big, and a smaller one in the vicinity of the hyperplane.…”