Synthesis and critical study of sampled-data control systems

In the last few years, there have been few papers1-9 which discuss methods of analysis and synthesis of sampled-data control systems. In this paper it is shown that the z-transform method is the best as applied to the design of such systems. The z-transform method yields information only on the response of the system at sampling instants. Certain methods have been introduced which modify the z-transform method to obtain information on the system's behavior between sampling instants. All these proposed methods are mainly directed for analysis purposes. However, none is applied for design procedures which can be consolidated with the z-transform method. In this work, the modified1 z-transform method is further extended and applied for synthesis procedures. It is believed that the method chosen is best applicable for the design of sampled-data control systems. Both the frequency-response and the root-locus approach with the use of this modified z-transform method are discussed. Furthermore, the effect of pole and zero location on the transient response of sampled-data systems is investigated, and certain information on the response obtained.