Note on the relative degree of a flexible manipulator and implications to inverse dynamics for tracking control

This paper rechecks the relative degree of the end-point tracking control system of a flexible manipulator. New added insights into the ill-defined behavior of the relative degree are presented by constructing a perturbed truncation model. The implications for the inverse dynamics motivate us to reformulate the inverse dynamics based on the perturbed truncation model in the extreme case of truncating all of the flexible modes. New potential advantages arising from this novel formulation are investigated for the inverse dynamics control design as well.