Nonlinear output feedback control for stepper motors: a robust adaptive approach

Nonlinear adaptive output feedback control of stepper motors is considered. Utilizing the phase currents as inputs, an adaptive controller is derived for permanent magnet and variable reluctance stepper motors that achieves robustness to parametric and dynamic uncertainties, such as friction, load torque or cogging torque in the motor dynamics. The controller utilizes only the rotor position for feedback and achieves global uniform boundedness of the tracking error. The design methodology is based on our earlier work (1997) on robust adaptive control of nonlinear systems. The stability of the system is proved through Lyapunov techniques. Simulation results are depicted to illustrate the performance of the controller.