Spiking-Free Disturbance Observer-Based Sliding-Mode Control for Mismatched Uncertain System

Abstract For the mismatched uncertain system, a novel spiking-free disturbance observer (DO)-based sliding-mode control (SMC) scheme is developed. First, a DO is proposed to estimate the mismatched uncertainty. A new sliding-mode surface is developed by using the system states, the estimation of mismatched uncertainty, and a spike suppression term. Then, an SMC method is proposed by using the developed sliding-mode surface. Compared with existing SMC schemes, the proposed spiking-free DO-based SMC has two advantages: (1) the mismatched uncertainty can be effectively suppressed; (2) the harmful spike problem of extended disturbance observer (EDO)-based and extended state observer (ESO)-based SMC schemes when the observer gain is high can be avoided. Finally, the simulation is presented to show the effectiveness of the proposed scheme by comparing the proposed and existing SMC schemes.