MIMO jerk derivative feedforward for motion systems

This paper shows that flexible modes in motion systems result in residual dynamics that can not be reduced using conventional acceleration feedforward and static decoupling. When reference trajectories with low frequency excitation are applied, low frequency tracking errors and cross-talk errors occur as peaks during jerk phases of a motion. A multivariate jerk derivative feedforward controller is presented which compensates for the joint contribution of all flexible modes in the low frequency region. Furthermore it is shown that no higher order (than 4) feedforward controller is required to improve low frequency tracking performance. A simulation example of a positioning device shows a significant improvement of the tracking performance