Zero Phase Error Tracking Algorithm for Digital Control

TLDR

The algorithm is particularly suited to general motion‑control problems such as robotic arms and positioning tables. A digital feedforward control algorithm for tracking desired time‑varying signals is presented. The controller cancels all closed‑loop poles and cancellable zeros, removes phase shift from uncancellable zeros (including those outside the unit circle), and its effectiveness is demonstrated on a typical motion‑control problem. The phase cancellation ensures a zero‑phase frequency response between desired and actual outputs across all frequencies.

Abstract

A digital feedforward control algorithm for tracking desired time varying signals is presented. The feedforward controller cancels all the closed-loop poles and cancellable closed-loop zeros. For uncancellable zeros, which include zeros outside the unit circle, the feedforward controller cancels the phase shift induced by them. The phase cancellation assures that the frequency response between the desired output and actual output exhibits zero phase shift for all the frequencies. The algorithm is particularly suited to the general motion control problems including robotic arms and positioning tables. A typical motion control problem is used to show the effectiveness of the proposed feedforward controller.