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Multi-rate Feedforward Tracking Control
for Plants with Nonminimum Phase Discrete Time Models
Yuping Gu and Masayoshi Tomizuka
Abstract
This paper is concerned with performance enhancement of tracking control systems by multi-rate control. The
feedback controller is updated at the same rate as the sampling rate of the output measurements. The feedforward
controller processes the desired output signal for high accuracy tracking, and its output is updated at a rate N-times
faster than the sampling rate of the output measurements. The discrete time model of the controlled plant may
possess unstable zeros, and the zero phase error tracking controller (ZPETC) is used as a feedforward controller.
Inter-sample behavior of the plant is included in evaluating the tracking performance of the multi-rate system.
Illustrative examples are given to show advantages of the proposed multi-rate feedback/feedforward control
scheme.
Keywords:
multi-rate control, feedforward control, digital control.
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