Frequency-response of Sampled-data Systems II: Closed-loop Consideration

Abstract

The second part of the theory which provides a frequency-domain paradigm for the design of sampled-data control systems is developed. In this paper, we define sensitivity FR-operator S(jφ) and complementary sensitivity FR-operator T(jφ) for closed-loop control systems, and show that S(jφ) gives the improvement of the sensitivity of the transfer characteristics from the reference to the controlled output and also represents the ability of rejecting disturbances, and that T(jφ) represents the degree of robust stability and, at the same time, gives the effect of detection noise. We also show S(jφ) + T(jφ) = I and thus establish a frequency domain paradigm for the design of sampled-data control systems, which is parallel to the continuous-time case.