Integrated terminal sliding with enhanced repetitive control for nono-positioing stage

This paper proposes a discrete time terminal sliding mode with enhanced repetitive controller (DTSMERC) for nano-positioning system. The hybrid control structure incorporated the desirable features of enhanced repetitive control (ERC) and discrete terminal sliding mode control (DSMC) to accomplish a high precision performance for periodic reference tracking in the presence of system perturbation for PEA applications. The repetitive component is to cope with periodic error at steady state, hence, tracking of periodic reference signals can be improved. While, the DTSMC controller is design to speed up the settling time and achieve the baseline servo performance. In addition, the hysteresis effect is considered as an external disturbance. Moreover, the issue of non periodic disturbance amplification with conventional repetitive control (CRC) is considerably alleviated by adopting the ERC. The system stability is proved based on Lyapunove criteria, and also the details design with theoretical analysis of the proposed DTSMERC are presented in this work. The effectiveness of the proposed DTSMERC is verified through a compression of simulation tests with DTSMC and linear proportional-Integral RC (PIRC) for a PEA plant model.