Robust Control of Position and Force for a Robot Manipulator in Non-Contact and Contact Tasks

The problem of designing a robust controller for position and force control of a robot manipulator in both non-contact and contact tasks is considered. Using classical dynamics concepts, and under certain assumptions, a mathematical model for non-contact and contact tasks is developed. A controller based on proportional-integral (PI) and feedforward control is proposed for this model. A sufficient condition, which ensures that the closed-loop system is asymptotically stable, and the proposed controller are both presented. Theoretical analysis and numerical simulations have shown that the proposed controller is robust with respect to perturbations in system parameters and joint friction force. It is shown in this paper, that there is no need to change the controller configuration when the robot comes into contact with the environment from free motion.