Positioning and Vibration Control of a Magnetostrictive-Actuated Stewart Platform with Hysteresis Compensation

In this paper, we present a hybrid adaptive feedforward and feedback controller with hysteresis compensator on a magnetostrictive-actuated Stewart platform. The Stewart platform is applied for positioning and vibration control integrally. It is challenging to develop an effective controller to systematically address the issues of multi-strut motion coupling, strut hysteresis and dynamics for the Stewart platform. Magnetostrictive hysteresis leads to the loss of closed-loop output performance with conventional linear controller. To this end, a novel comprehensive controller is proposed in this paper. With the inverse kinematics analysis, the spatial motion of the mobile plate is decoupled into the independent motions of six actuator struts. In terms of controlling the single strut, the hybrid adaptive feedforward (AFF) and PID feedback controller with asymmetric hysteresis compensator (HC) is constructed. The arctangent-polynomial modified Prandtl-Ishlinskii (APMPI) model is used to build the inversion-based hysteresis compensator. The experimental system is developed. The positioning and vibration isolation experiments are conducted. Experimental studies show that the output performances are best with the proposed controller compared against sole AFF, hybrid AFF and PID controllers.