Robust adaptive nonlinear control for robotic manipulators with flexible joints

The robust adaptive control problem for a multi-link robotic manipulator with fl exible joints is considered in this chapter. A general uncertain dynamic model of a robotic manipulator with joint fl exibility is considered including uncertainties in joint stiffness, Coriolis and centrifugal terms, friction, gravity, load torques and disturbances, and actuator inertia. Only the inertia matrix of the rigid links of the robotic manipulator is assumed to be known. A robust adaptive dynamic controller is designed through vector backstepping with adaptations for the joint stiffness matrix, actuator inertia matrix, and a lumped uncertain constant representing the other uncertainties in the system. It is shown that the designed dynamic controller provides global stabilization and practical tracking of reference trajectories specifi ed for each of the joint variables. The effi cacy of the designed dynamic controller is demonstrated through simulation studies on a two-link manipulator with joint fl exibility.