Stability analysis and compensation of time delays in analog control systems

Abstract

Time delays, also known as transport lag, dead time or time lag, are components that hold signal flow off inside the systems. They arise in physical, chemical, biological and economic systems, as well as in the processes of measurement and computation. Time delays can be approximated using polynomial series to allow the systems be analyzed in the same manner as the non time-delay systems. In this paper, we study the influences of delay components to system’s stability, derive the Nyquist stability criterion for time-delay systems and use it to analyze stability of the systems, and utilize some polynomial series to approximate the delays and examine their performances. Moreover we study PID controller as delay compensation scheme using two tuning methods: the “iterative method” and Ziegler-Nichols method.