The Applications of Compliant Motion Control Technique on 6-DOF Hydraulic Parallel Mechanism

Most interaction control formulations focused on electrically driven parallel mechanism. In this paper, the combining practice applications of compliant motion control technique on six degrees of freedom (6-DOF) hydraulic parallel mechanism (HPM) are investigated. According to the manipulation task specification and hydraulic control system characteristics, three different compliant motion control schemes are presented in three typical application scenarios, respectively: a parallel position/force control scheme in the joint space coordinate for train curve negotiation performance test, a hybrid position/force control scheme with the internal force suppression for shaking table with actuation redundancy, and a hybrid impedance control scheme for auto-docking mechanism based on force and vision. The feasibility and effectiveness of the proposed schemes were verified through a series of experiments. It showed that the 6-DOF HPM achieves good compliant behavior by applying the proposed compliant motion control techniques. These schemes could also be extended to other applications where the compliant motion of the 6-DOF HPM is required.