Active Second-Order Pole-Zero Cancellation Control for Speed Servo Systems With Current Sensor Fault Tolerance

This brief presents an advanced output-feedback technique for speed regulation tasks in servo systems, which reduces the system model independence and is independent of the current feedback, leading to fault tolerance. Hence, the output position error drives the model-free order reduction filter for speed, and the acceleration feedback (as a replacement for the current loop) is admissible. Furthermore, the proposed control law includes specially structured active damping terms in the feed-forward loop to actively trigger second-order pole-zero cancellation, forming a simple single-loop proportional-integral derivative-type structure with compensation terms. Finally, a 420-W prototype DC servo system experimentally validates the effectiveness of the proposed technique.