On adaptive control of force controlled manipulators-implementation and experimental results

The authors deal with the implementation of adaptive control of force-controlled manipulators. Due to the hardware and software limitations of existing industrial robots, the force control loop must be realized in many cases with an inner velocity and position controller. In such cases, the response of the robot becomes sensitive to the changes of the environment stiffness. To solve the problem, an adaptive controller has been proposed by many authors. The main drawback of these controllers is that they cannot assure satisfactory behavior in the case when both environment stiffness and environment/robot contact position are changed simultaneously. Therefore a dual force sensor is proposed that is passive and active. which allows estimation of the contact position and the environment stiffness simultaneously. Adaptive force control was tested on the deburring process of a workpiece.