Adaptive force control with active damping for robot manipulators with bounded inputs

At present, there are several tasks automated by robotic systems that require a precise regulation of the applied force to achieve an adequate robot-environment interaction. To address this control problem, this paper presents an explicit force control structure that has two very relevant features for interaction tasks: (1) the operation of robot actuators within a safe region is guaranteed without exceeding their torque limits, and (2) the parametric uncertainty related to gravitational forces and environment stiffness is compensated. The structure of the proposed control scheme is based on generalized saturation functions; therefore, bounded control actions are obtained without restricting the tuning of gain parameters to achieve an adequate performance. In addition, in order to achieve a compliant robot-environment interaction, the controller structure also includes a speed-dependent active damping term that uses generalized saturation functions to obtain a bounded response. Furthermore, the proposed explicit force controller is supported by a rigorous stability analysis via Lyapunov's theory. Finally, a numerical simulation test is presented to validate its correct performance, using the dynamic model of a three-degree-of-freedom robot manipulator interacting with a rigid environment.

Automated summary

This paper presents an explicit force control structure for precise regulation of robot-environment interaction, addressing issues such as safe operation, compensation of parametric uncertainty, and bounded response. The proposed control scheme is based on generalized saturation functions and is supported by stability analysis using Lyapunov's theory. A numerical simulation is conducted to validate its correct performance.