Robust tracking control design for a 6 DOF parallel manipulator

The focus of this work is on a robust tracking control design for a 6 DOF parallel manipulator in the presence of nonlinearity and fast (or slowly) time-varying uncertainty. Two types of controllers are presented. The controls are based on the Lyapunov approach and guarantee a practical stability. The controls utilize the information of link displacements and its velocities. The first control scheme uses the quadratic Lyapunov function and other uses the geometry dependent Lyapunov function, which excludes the inverse matrix computation on the inertia matrix. Also, the hydraulic dynamics is considered in the control design and control performance. The control performances of the proposed algorithms are verified by simulations and experiments. (C) 2000 John Wiley & Sons, Inc.