Stable inversion control for flexible link manipulators

Abstract

We consider the inverse dynamics problem for robot arms with flexible links, i.e., the computation of the input torque that allows exact tracking of a trajectory defined for the manipulator end-effector. A stable inversion controller is derived numerically, based on the computation of bounded link deformations and, from these, of the required feedforward torque associated with the desired tip motion. For a general class of multi-link flexible manipulators, three alternative computational algorithms are presented, all defined on the second-order robot dynamic equations. Trajectory tracking is obtained by adding a (partial) state feedback, within a nonlinear regulation approach. Experimental results are reported for the FLEXARM robot.