Decentralised fault tolerance and fault detection of modular and reconfigurable robots with joint torque sensing

Abstract

A decentralised approach to fault tolerant control and fault detection is proposed for modular and reconfigurable robots with joint torque sensing. The proposed fault tolerant control scheme is independent of fault detection, avoiding the chances of delay being introduced by the detection scheme on the fault tolerant control algorithm. Based on a unique joint by joint control approach, the proposed fault tolerant controller for each module neither requires motion states of any other modules, nor the link dynamics. The addition or removal of modules does not affect the control of other joint modules. Uncalibrated torque sensor signals are utilized and actuator performance degradation is considered. Faults are detected and corrective measures are taken at the module level. An observer-based fault detection algorithm is proposed by using a residual generated from the joint velocity estimation and measured joint velocity. Simulation and experimental results have confirmed the effectiveness of the proposed fault tolerant control and fault detection schemes.