Gaussian Dynamic Gain Sliding Mode Position Control of Flexible Servo Systems

Abstract

In the position control of a flexible servo system (FSS), the use of sliding mode control (SMC) with a fixed constant sliding surface leads to overshoot in the step position response. This paper first clarifies through analysis that the acceleration error and jerk error in the constant-coefficient sliding surface are the core causes of this overshoot phenomenon, both of which will generate accelerating current during deceleration. To address this issue, a Gaussian dynamic gain sliding mode control (GDG-SMC) strategy is proposed. By designing a sliding surface with GDG, the proposed strategy increases the proportion of the velocity error and the reaching law component in the q-axis current during deceleration, thereby generating braking current to suppress overshoot. Coupled with an anti-windup super-twisting reaching law to mitigate the overshoot potentially induced by the integral term, the proposed method can further reduce the position response error and realize fast overshoot-free position tracking. Comparative experimental results verify the feasibility of the proposed method.