IMPROVING THE STABILITY OF LIMITING ZEROS IN DISCRETE-TIME MODEL FOR NONCOLLOCATED MASS-DAMPER-SPRING MULTIVARIABLE SYSTEMS VIA GENERALIZED SAMPLE HOLD FUNCTION

摘要

It is well-known that unstable zeros limit the achievable control performance. This paper is concerned with the stability of sampling zeros of discrete-time models for mass-damper-spring (MDS) systems with noncollocated sensors and actuators in the case of the generalized sample hold function (GSHF). The asymptotic behaviors of the sampling zeros, for a discrete-time model of a noncollocated MDS system with a GSHF, are analyzed for a sufficiently small sampling period T and the linear approximate expressions are also obtained. In addition, the linear approximate expressions with respect to the sampling period T lead to a sufficient condition for the sampling zeros of the discrete-time model to lie inside the unit circle for a sufficiently small sampling period T. It has been shown that the GSHF can locate the sampling zeros of discrete-time models for noncollocated MDS systems inside the stable region and improve stability properties when the zero-order hold (ZOH) cannot. Moreover, the examples are shown to demonstrate a significant improvement of control performance compared with the use of a ZOH.