Nonhomogeneous material milling using a robot manipulator with force controlled velocity

This paper deals with problems that arise when robot manipulators are used in milling workpieces with nonhomogeneous material. Damages to the cutting tool and workpiece would occur if the cutting speed is set incorrectly with respect to the characteristics of the tool and the hardness of the workpiece material. This concern is heightened when milling materials which are nonhomogenous where the tool drag can vary unpredictably. It is proposed in this paper that we solve the problem by employing a force controlled velocity (FCV) strategy to automatically adjust the cutting speed in response to the force exerted at the tool tip along the cutting path. The idea of FCV is accomplished by using a nonlinear function of both force and elapsed time in place of elapsed time when evaluating the robot trajectory equation. The effectiveness of this approach is confirmed by simulation and experimentation.