Robust adaptive control of permanent magnet stepper motors

Robust adaptive nonlinear control of permanent magnet stepper motors is considered in this paper. A robust adaptive controller is designed for the plant that is robust to parametric and dynamic uncertainties. The uncertainties are assumed to be bounded by polynomials in the states. A commutation strategy is applied to define desired currents that would produce the desired torque signals. These desired currents then become the tracking objective for the electrical subsystem. Voltage level control inputs are designed using backstepping and the robust control design methodology to track the desired currents. The overall stability of the system is shown using Lyapunov techniques. The tracking errors are shown to be globally uniformly bounded.