Fuzzy Event-Triggered Super Twisting Sliding Mode Control for Position Tracking of Permanent Magnet Synchronous Motors Under Unknown Disturbances

In this article, we propose the fuzzy event-triggered super twisting sliding mode control (STSMC) approach for improving the position tracking performance and reducing the communication resource under various unknown disturbances in the control system of permanent magnet synchronous motors (PMSMs). The event-triggered strategy is designed to minimize the unnecessary use of computation/communication resources while achieving acceptable control performances. However, when the unexpected disturbances are injected, the tracking performance could be degraded since the conventional event-triggered strategy using previous tracking error information cannot immediately update the control input according to rapid unexpected disturbances. To resolve this problem, we design the fuzzy rule, which is applied in the event-triggered strategy to adjust the updating time based on the tracking error at the present time to achieve robustness against unexpected disturbances. Thus, a fuzzy event-triggered control input can be transmitted immediately to the PMSM when an unexpected disturbance occurs. The STSMC method is designed to enhance the position tracking performance under disturbances. The stability of the closed loop is shown using the modified Lyapunov theory. In addition, the nonexistence of Zeno execution is guaranteed by analyzing the minimum bounded event-triggered interval time. The effectiveness of the proposed method was verified through simulations and experiments, where the experiment was conducted using a PMSM testbed.