Compensation of Performance Degradation Caused by Fault Based on GIMC Structure

—Application to a Redundant Sensor Fault of Flexible Arm—

Abstract

In recent years, control system reliability has received much attention with increase of situations where computer-controlled systems such as robot control systems are used. In order to improve reliability, control systems need to have abilities to detect a fault (fault detection) and maintain the stability and the control performance (fault tolerance). This paper deals with the strain gauge sensor fault of a flexible arm robot. In order to achieve a fault-tolerant control system, the effect of the fault is identified as dual Youla parameter by regarding the estimation error of the faulty sensor signal as the faulty plant output. Moreover, Youla parameter is designed so as to suppress the effect of dual Youla parameter. Youla parameter is implemented in GIMC (Generalized Internal Model Control) structure proposed by Zhou. Since GIMC structure includes a conditional feedback, it is suitable for achieving a fault-tolerant control system. The effectiveness of the proposed fault-tolerant control system is confirmed by some experiments.