Adaptive force control for position-controlled robot manipulators

This paper presents an adaptive force control method for robot manipulators based on Popov´s hyperstability criterion. As many researchers have found, one of the difficulties of the control problem is that the stability of the robot force control system is sensitive to the changes of the stiffness of the environment on which the force is exerted. To solve the problem, model reference adaptive control theory is used to identify the environment stiffness, and to determine an adaptive force feedback gain corresponding to the contacted environment. The theoretic analysis and experimental results show that this method can realize a stable force control when the environment stiffness changes to a sufficiently large extent.<>