Control of elastic robot manipulators

In this paper a robust control strategy is proposed for the trajectory tracking control of multi-link elastic robot manipulators. The robustness against both of the structured uncertainty caused by the nonlinear mechanical structure and the unstructured one caused by elasticity of links is taken into account in designing controllers. For this purpose the model of elastic robot manipulators is decomposed into the slow model and the fast model by using an integral manifold approach. The slow controller, which is robust against the structured uncertainty, is designed for the slow model on the basis of VSS theory. On the other hand, the fast controller, which is robust against the unstructured uncertainty, is designed for the fast model on the basis of H-infinity control theory. Then the composite control is constructed with the slow controller and the fast controller. Some results of numerical simulations are presented to show the effectiveness of this design procedure.