Position tracking control for robot manipulators driven by induction motors without flux measurements

In this paper, we present a voltage input controller for robot manipulators actuated by induction motors. The control is designed to compensate for the nonlinear dynamics associated with the mechanical subsystem and the electrical subsystems while only requiring measurements of link position, link velocity, stator winding currents, and exact model knowledge. Specifically, through the use of nonlinear observers for rotor flux and an observed integrator backstepping approach, we obtain semiglobal uniform ultimately bounded link position tracking. The result is semiglobal in the sense that a control parameter must be made sufficiently large relative to the electromechanical initial conditions in order to guarantee that control singularities are avoided. To provide insight into the design procedure, the controller is first presented for a one-link robot manipulator system. We then extend the controller from the one-degree of freedom system to the multidegree of freedom system. Experimental results are then presented to illustrate the performance of the proposed approach applied to a one-link robot. Finally, simulation results are presented to illustrate the tracking performance for the proposed controller applied to a two-link robot manipulator system.