Showing papers by "James S. Freudenberg published in 1991"
TL;DR: In this paper, an integral constraint on the closed-loop transfer function of unstable open-loop systems is used to quantify a tradeoff between feedback properties of the closedloop system.
Abstract: An integral constraint on the closed-loop transfer function of unstable open-loop systems is used to quantify a tradeoff between feedback properties of the closed-loop system. This results in a lower bound on the peak of the complementary sensitivity function for unstable plants. The lower bound illustrates the nature of the tradeoff that is imposed, and provides insight into the difficulties imposed on the control of unstable systems. It can be used to quantitatively evaluate tradeoffs between the frequency of the open-loop unstable pole, the peak of the complementary sensitivity functions, and the bandwidth of the closed-loop system. Such a relationship has long been recognized, and is embodied in the classical design rule of thumb which states that the closed-loop bandwidth must be at least twice as large as the frequency of the unstable pole. Results which give insight into this rule and a theoretical basis for it are provided. >
43 citations
26 Jun 1991
TL;DR: In this paper, the authors studied the asymptotic behavior of the sensitivity function and loop transfer function in non-minimum phase (NMP) plants. But the results were limited to negligible computation time and significant computation time cases.
Abstract: The purpose of this paper is to study what happens when the discrete-time loop transfer recovery (LTR) procedure is applied to nonminimum phase (NMP) plants. Explicit expressions are given for the asymptotic behavior of the resulting sensitivity function and loop transfer function. Both the negligible computation time and significant computation time cases are treated. These results yield a better understanding of the mechanism of the discrete-time loop transfer recovery procedure and the design limitations due to NMP zeros and computation time delays.
13 citations
TL;DR: In this paper, an upper bound stated in the title papers is shown to be incorrect, and the conclusions reached using the incorrect upper bound remain valid, and a correct result is derived and shown that the incorrect bounds remain valid.
Abstract: An upper bound stated in the title papers is incorrect. We derive a correct result and show that the conclusions reached using the incorrect bounds remain valid.