Event-Triggered Modified Repetitive Control for Periodic Signal Tracking

Abstract

A broad range of practical systems need to perform periodic tasks, such as the mechanical hard-drive read-write arm system, the robotic arm, certain circuitry systems, etc. Based on the internal model principle, repetitive control (RC) is proved to be effective for periodic signals/disturbances tracking/rejection. However, existing RC methods mostly require constant update of the control input, regardless of whether it is needed or not, which results in a good deal of unnecessary communication resources and wear of the actuators. To overcome this drawback, in this brief, the event-triggered strategy is for the first time considered in the repetitive control system to reduce the update frequency of the control input. A novel event-triggering condition, which takes into account both the current and last periods' error information, is embedded in a modified repetitive control system. Thus, the control input will not be updated until the designed error signal exceeds a predefined threshold. A continuous-discrete 2-D model is adopted to model and analyze the event-triggered modified repetitive control system. The performance of the developed control scheme is then verified through the simulation results.