Improved terminal sliding mode control for manipulator in high-precision force control machining tasks

Abstract This paper proposes an improved terminal sliding mode control impedance control method (ISMIC) for manipulators to keep the contact force constant during machining. Firstly, environmental uncertainties and impedance model uncertainties are introduced into the traditional impedance model to derive an impedance model that includes the effects of uncertainties factors and estimation of uncertainty using a disturbance observer. Then, a finite-time convergence controller is designed with a terminal sliding mode surface, and an improved reaching law is chosen. Finally, the machining process is simulated with the proposed controller and compared with previous literature. Simulation results show that the control method proposed in this paper improves the convergence accuracy by more than 93.6% compared to similar control methods in the literature. This method can greatly improve the accuracy of force control and has the potential for practical application.