Fault-tolerant robot manipulators based on output-feedback H∞H∞ controllers

This paper develops two fault-tolerant control strategies for robot manipulators. The first is based on linear parameter-varying systems and the second on Markovian jump linear systems. Firstly, it is shown that with the LPV approach post-fault stability is guaranteed only if the robot stops completely after a fault detection. Then, with an underactuated configuration, the manipulator can be controlled appropriately. Secondly, it is shown that with the fault-tolerant system based on Markovian jump linear systems, stability is guaranteed after a fault is detected even with the robot still moving. This approach incorporates all manipulator configurations in a unified model. Both strategies have been implemented based on output-feedback H∞H∞ controllers, which are the main focus of this paper. Experimental results illustrate the performance of each controller.