Tracking control of multi-linked robots based on terminal sliding mode

For the trajectory tracking control problem of biped multi-linked robots with uncertain disturbances, a global finite-time tracking controller is proposed based on terminal sliding mode control method. First, according to the features of forward dynamic model of biped multi-linked robots, the sliding mode controller is designed based on the terminal sliding mode theory. Under the designed controller, the tracking error will not only reach the terminal sliding mode surface from any initial states but also converges to the origin along the sliding mode surface in finite time . Second, due to the non-continuity of the controller, the chattering phenomenon occurs. To this end, a modified saturation function is utilized to substitute the sign function in the designed controller, and thus the chattering can be eliminated. Finally, simulation results verify the effectiveness of this method.