Nonlinear adaptive motion control for a manipulator with flexible joints

The authors present an adaptive control scheme for trajectory tracking of robot motion. A dynamic model of a manipulator with flexible joints that is particularly useful for derivation of the control law is adopted. Based on this model, a two-stage controller consisting of a feedback loop and a parameter adaption loop is established. It is shown that without precise knowledge of the parameters of the manipulator and its joint flexibilities the tracking error converges to zero asymptotically. This implies robustness of the control scheme to the variation of payload or parameters as long as their rate of change is moderate. The convergence can be sped up by increasing the suitable controller gains