Event-Triggered Time-Varying ADRC Approach for Pneumatic Parallel Manipulator

In this paper, a novel event-triggered time-varying active disturbance rejection control (TADRC) approach is developed for pneumatic parallel robots, which can improve the performance of trajectory tracking and the capability of disturbance rejection in the case of reducing the sampling cost. The proposed TADRC includes three parts, tracking differentiator (TD), time-varying extended state observer (TESO) and time-varying nonlinear error feedback controller (TNEFC). The TESO is also provided with time-varying gains to improve the transient performance of the estimation error systems and accuracy of disturbance estimating error. Based on the TD and observation results, the proposed TNEFC can be dynamically improve the control speed and accuracy, and the closed-loop system stability is also guaranteed. Finally, the control strategy is applied to PPMs, and the simulation results are conducted to verify the efficiency.