Vibration suppression control of flexible robots using velocity inputs

Research on vibration suppression control of flexible robots has concentrated mainly on the one-link and two-link planar manipulators. Most of the techniques that have been presented can not be easily extended to the case of a general 3D flexible robot. In this paper we present a general control scheme upon the basis of hardware velocity servo cards. The velocity commands to move the robot are calculated by adding a vibration suppression term to the joint position feedback employed in 'rigid' robots. Two different methods are proposed to calculate this term, one based on optimum quadratic control and the other based on pseudo-inverse non-linear decoupling. These techniques are studied numerically in the case of a real 2-link 3-joint flexible robot, by computing the values of the closed-loop poles at different configurations. Experiments of position stabilization of the robot prove the validity of our methods.