Adaptive Sliding‐Mode Control for Permanent Magnet Spherical Actuator Based on Trajectory Re‐Planning

Abstract

This study proposes an adaptive sliding‐mode control strategy based on trajectory re‐planning for a permanent magnet spherical actuator (PMSA) to address the large overshoot caused by substantial initial error while maintaining tracking precision. The proposed re‐planning technique reconstructs a local trajectory without the preceding knowledge of the desired position in the future, which makes this technique more suitable for reconstructing trajectory given online. First, a re‐planning cool‐down term is added to maximize the capability of controller to improve the precision and speed of tracking. Moreover, a smooth switching technique is also applied to further improve the precision of trajectory tracking and stop redundant re‐planning when the system enters satisfactory state. Finally, the proposed trajectory re‐planning strategy is combined with a robust adaptive sliding‐mode controller (RASC), which effectively reduces friction, delay, and external uncertainty disturbances. The effectiveness of the proposed control design is verified by both simulation and experiment on PMSA, which can provide reference for the further engineering application of multi‐degree‐of‐freedom system. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.