Vibration Robust Optimal Semi-Active Control of Multi-Dimensional Vibration Isolator Based on Parallel Mechanism

In order to isolate multi-dimensional vibration experienced by vehicle-mounted precise instrument, a novel multi-dimensional vibration isolator is proposed based on 2-RPC/2-SPC parallel mechanism and the magneto-rheological (MR) damper. The kinematic and dynamic models are established by geometric relation and the Lagrange approach respectively. The robust optimal semi-active control algorithm is obtained by deducing linear matrix inequality. The vibration isolation capability is addressed in time and frequency domain under stochastic road excitation with mass, stiffness, and damping coefficient uncertain factors respectively. Meanwhile, the relation between isolation performance and uncertain factors is explored. The isolation capability is compared with the linear quadratic regulator (LQR) semi-active control algorithm with the same uncertain factors under step excitation. The results demonstrate that the proposed isolator inhibit the vibration in the x, y, z axes and around the y axis significantly. The isolation performance is affected by mass uncertain factor most obviously. The robust optimal semi-active control algorithm is more effective than the LQR algorithm with uncertain factors.