Dynamic modeling and control for a five-dimensional hybrid vibration isolator based on a position/orientation decoupled parallel mechanism

Abstract

In this study, a novel five-dimensional hybrid manipulator applied to multi-dimensional (MD) vibration isolation is proposed, a semi-active fuzzy optimal control model is established and the performance of the isolator is validated by the MD vibration isolation experiments. In the hybrid manipulator, the translations and rotations of the manipulator are decoupled and each actuator is replaced by a subsystem combining a magnetorheological (MR) damper with a spring to realize the spatial MD vibration isolation. The primary structure of this MD vibration isolation system (VIS) or multi-dimensional vibration isolation system (MDVIS) is described and the relating isolation principle is explained. Consequently, the closed dynamic model is established so that a fuzzy control model is built to implement vibration control. In the control model, the optimal damping force is obtained from an $H\infty$ state feedback control strategy, and the actual output force of the MR damper is determined with a kinematics parameters in every limb according to the work principle of the MR damper. In addition, a Takagi-Sugeno fuzzy model is obtained by a genetic algorithm to obtain the input current of the MR damper. To validate the VIS performance, an MD vibration isolation platform (VIP) or multi-dimensional vibration isolation platform (MDVIP) prototype is developed to study the vibration isolation performance. Finally, vibration experiments with sinusoidal and random excitations in translational direction are conducted. Ultimately, the measurement results of vibration acceleration validate the effectiveness of the hybrid vibration isolator and its control strategy.