QFT robust control of hydraulic driven stewart platform using dynamics real-time compensation

A Quantitative Feedback Theory (QFT) control strategy using dynamics real-time compensation is put forward to solve the inferior servo tracking problem derived from the severe dynamics coupling and the model uncertainty in the hydraulic driven six degree-of-freedom parallel motion platform. The control theme consists of the compensation channel and the main closed-loop control channel. Based on the dynamics equation of the Stewart platform and the control mathematical model of the driven parts, the compensation channel realizes the dynamic feed forward for the modeled disturbance force according to the principle of equivalent control architecture. To improve the robust stability of the uncertain system and the ability of the reduction of the unmodeled disturbance force, the main feedback control loop adopts the QFT controller. The experimental results indicate that, with this control strategy, the response time, movement accuracy and resistance to load disturbance of the system can be improved, the system has good performance in tracking, and the dynamical coupling and unknown disturbance can also be greatly compensated.