ABSTRACT
As pointed out in Chapter 1, with the widespread use of computers in control loops it is inevitable that control engineers will face problems associated with sampled-data systems. Such systems by their very definition contain a mixture of continuous-time and discrete-time signals. A common problem that arises with sampled-data control systems is to find the equivalent effect of continuous-time operations as seen by the computer in the loop. Typically, the modeling of the signal converters assumes an ideal uniform sampler for the analog-to-digital converter and a simple (zero-order) hold device synchronized with the samples for a digital-to-analog converter. with these assumptions one may find in many references the standard zero-order hold model, also known as the step in variant (SI) model which will be discussed subsequently.
