A robust mixed H2/H∞ tracking control for 3-DOF permanent magnet spherical actuator

This paper addresses a robust mixed H
₂
/H
_∞
control for 3-DOF Permanent Magnet (PM) Spherical Actuator in order to improve its trajectory tracking performance. The dynamic model of the PM spherical actuator is a multi-variable nonlinear system contains uncertainties such as model errors and disturbances inevitably, which will gravely influence the performance of the control system. Therefore, a mixed H
₂
/H
_∞
control algorithm which consists of H
₂
and H
_∞
control theory is design to compensate for these uncertainties. The robust mixed H
₂
/H
_∞
control algorithm aim at attenuate the effects of the model uncertainties and external perturbations. To illustrate the effectiveness of the proposed control algorithm, both simulations and experiments are conducted. The results have shown that the proposed control algorithm has better trajectory tracking performance and strong robustness to uncertainties.