Design of Auxiliary Signals to Improve Performance of Self-repairing PID Control

Self-repairing PID control has been proposed as an active fault-tolerant control system that tolerates component malfunctions, maintaining desired performance. In this method, an auxiliary signal with the same sign as the control quantity is added to the integrator to cause minute oscillations in the control quantity, and a fault is diagnosed by detecting the bias in the integral value due to the occurrence of a fault. This method has the tradeoff that a larger auxiliary signal reduces fault detection time but negatively affects control performance. This paper proposes the auxiliary signal whose value is determined by the function of the control quantity to improve the performance of the self-repairing PID control. Simulation results show that the function of the auxiliary signal effectively reduces detection time and improves control performance. Additionally, the performance of the system is evaluated while varying the design parameters, and some insight into the design guidelines for the function is found. © 2024 The Institute of Electrical Engineers of Japan.