Revising the robust control design for rigid robot manipulators

Robust controllers for robot manipulators ensure stability properties of the closed loop system, even if only partial knowledge of the dynamic model of the manipulator is available. Existing derivations of robust control laws, while guaranteeing the stability result, present an undesired interaction between the gains of the controller of the nominal system and the robust control term. Based on a structured representation of the model uncertainty, this paper presents a derivation of the robust control law where these limitations are removed. A case study is discussed to show the benefits of the proposed approach. New insight in the robust control problem for more general mechanical systems might arise from structuring the model uncertainty as proposed in this paper.