Fault-tolerant control of robotic manipulators with/without output constraints

Abstract

This paper investigates the tracking control problem of rigid robot manipulators with asymmetric output constraints and actuation faults. To lower the rigorous requirements on the initial conditions of system output, a novel output-dependent universal barrier function (UBF) is developed such that the normally employed conservative design of converting the output constraint into tracking error related constraint is removed. In addition, such control is also able to the robot free from output constraints without changing the control structure; To solve the time-varying yet undetectable faults of robotic manipulators in the long term operation, a robust method based fault-tolerant control (FTC) is proposed such that neither fault detection and diagnosis(FDD)/fault detection and identification (FDI) nor controller reconfiguration is required. Both theoretical analysis and numerical simulation verify the effectiveness and benefits of the proposed method.