Piezo-actuated vibration attenuation of the parallel robot Par2

Par2 is a two degrees of freedom high-speed and high-accuracy pick-and-place parallel robot. Considering trajectory accelerations at the order of 10g in its 3.5 kg charged end-effector, significant vibrations show up immediately after reaching a stop position, consequently jeopardizing operation cycle times. These vibrations, measured by three orthogonally oriented accelerometers, are particularly less damped in the direction normal to the trajectory plane. In order to actively minimize these vibrations, piezoelectric patches are wrapped around the robot arms. For this system, an identified model interconnected with an H∞ controller are calculated. Laboratory experiments attest the adequacy of the controller.