Variable-Performance Positioning Law for Hybrid-Type Stepper Motors via Active Damping Injection and Disturbance Observer

This brief proposes an advanced positioning law for hybrid-type stepper motors with two main features: a) a combination of pole-zero cancellation-based proportional-integral control with disturbance observers and b) a variable manifold forced to be exponentially convergent by the proposed control law. The parameter and load uncertainties are also explicitly handled in the controller design task. The practical improvement is confirmed with experimental evidence using a 10-W stepper motor controlled by two dual half-bridge drivers and a 32-bit digital signal processor.