Semi-active control for a multi-dimensional vibration isolator with parallel mechanism

Abstract

In this paper, a vibration isolation system based on a parallel mechanism is proposed to isolate the multi-dimensional (MD) vibrations. The parallel mechanism, which is composed of three uniform (Prismatic pair with spring and damper elements–Universal joint–Universal joint) limbs and two platforms, has three translational degrees of freedom. First, the isolator is introduced and the dynamic model is achieved by a Newton–Euler method. Further, a sliding mode controller is designed to obtain the optimal damping forces as the control strategy is very essential to a vibration isolation system. At the same time, the time-domain hard constraints are considered in the controller design as the damping force can only be produced along the direction contrary to the relative velocities of the MR damper’s two ends. Simulations results demonstrate that the semi-active isolator using MR dampers has fine performance in reducing MD vibrations.