This paper proposes a novel adaptive control approach for a robot manipulator to track a desired force signal while interacting with its unknown dynamic environment. Based on the bio-mimetic studies of human motor control functions, we propose a 2 degree of freedom adaptive control approach. In this approach, both force feedback and feedforward controllers are involved in the robot's control system. The feedback control is set as constant while the feedforward controller is adjusted online adaptively to approach the inverse of the force control transfer function. Using this approach, exact force tracking without any loop delay can be realized. The effectiveness and problems of this control approach are studied through computer simulations and robot experiments.
