The compound control of a Stewart mechanism for automatic assembly via co-simulation

Abstract

With the advantages of big bearing ability, strong stiffness, and high precision, the Stewart structure with six degrees of freedom (6-DOF) has found its way into the fields of military equipment, aeronautics, and astronautics. In this paper, a Stewart mechanism used for automatic docking is studied via the co-simulation approach. The low-speed performance with a heavy load is improved by the speed feedback compensation of parallel cylinders. Firstly, after trajectory planning, the compound control strategy with Coulomb-Viscous friction-based speed compensation is proposed. Subsequently, the co-simulation framework, including the structure model in LMS. Motion, the hydraulic model in AMEsim, and the control model in Matlab/Simulink are separately established with corresponding parameters. Finally, the compound control strategy is comparatively studied with displacement feedback alone. The control errors of cylinder displacement would decrease from ±1.0 mm to ±0.4 mm, which obviously improves the control performance.