Robust fault-tolerant control framework for robot manipulators with free-swinging joint failures: fault detection, identification and accommodation

In this paper, a robust fault-tolerant control scheme including fault detection, identification and accommodation for robot manipulators is presented to overcome the actuator failures. The joint fault considered in this paper is the free-swinging joint failure that causes the loss of torque on a joint. The presented fault-tolerant Cartesian control framework includes a normal control with normal (nonfailed) operation, a fault detection and a fault recovery control to achieve task completion and fault accommodation. After the detection and identification of joint failures, the robot manipulator with failed actuators can be considered as the underactuated robot manipulator. To show the feasibility of the proposed fault-tolerant control scheme, simulation results for a three-link planar robot arm are presented