Predictive compensation of time-varying computing delay on real-time control systems

Abstract

Computing time delay may have greatly degrading effects on control system performance. The effects of nonzero computing delay can be classified as delay or loss problems. This delay problem occurs when the time-varying computing delay is less than the constant sampling interval, and the loss problem exists when the computing delay is greater than the sampling interval. We propose a nearly all-pass narrow-band predictor to be used as a predictive compensator of the computing delay. The presented add-on prediction scheme is practical when the output of the controller can be approximated by a piecewise low-degree polynomial. An illustrative design example is presented, demonstrating the predictor's performance.