Non-linear robust control with partial inverse dynamic compensation for a Stewart platform manipulator

This paper presents a non-linear robust control approach for a Stewart platform manipulator with partial inverse dynamic compensation. Firstly, the complete model of the manipulator's dynamics is derived by using a Lagrange method that describes the motion of the upper platform and the six legs. Then, the coupling force caused by the dynamics of the legs is compensated using the Newton-Euler inverse dynamic formula, which makes the compensation algorithm much simpler without computing the complex forward dynamics. A robust tracking control approach is shown to cope with the uncertainties, including the modelling error and the remains of the partial compensation and the disturbances. The controller is designed based on the Lyapunov framework. It is shown that a simple feedback law that achieves the desired tracking performance can be designed by putting the physical property of the compensated system into the Lyapunov function. Finally, to verify the validity of the proposed approach, a simulation result is demonstrated.