Application of an H∞ control strategy to the parallel Delta

The work presented in this paper concerns the application of the H∞ robust control law to a highly nonlinear MIMO system: The three degrees of freedom direct drive Delta parallel robot. We first developed a state space dynamic model. Then, we carried out its linearization around an operating point. H∞ controller is synthesized based on the linear model. A Simmechanics 1 multi-body mechanical model has also been developed to simulate the kinematics and the dynamics of the robot and to validate the control results. To improve the tracking performances and increase the movement dynamics, the feed forward pre-computed torque has been considered. Two high speeds pick and place trajectories have been tested and robustness analysis through methodical simulation results are presented and commented.