H∞ control applied to the vibration minimization of the parallel robot Par2

Conceived for high-speed and high-accuracy pick-and-place tasks, the parallel robot Par2 aims at reducing industrial operation cycle times. As a consequence of its high acceleration levels, the end-effector precision at the stop positions is subjected to undesirable vibrations of the manipulator's arms, leading consequently to an increase in the cycle time. Piezoelectric patches are wrapped around the robot arms in order to actively minimize these vibrations, which are by their turn measured by three accelerometers orthogonally oriented and placed on the end-effector. After submitting the robot to an identification procedure, the obtained model is used to synthesize a reduced order H_∞ control law that succeeds in minimizing the residual vibrations.