ABSTRACT
In a digital control system, a digital device is used as the controller. The digital controller may be a hardware device consisting of permanent logic circuitry or a software device-a digital computer. Hardware controllers are inexpensive and fast, but lack flexibility or programmability. A software-based digital controller has programmable memory in addition to a central processor. The control algorithm is “programmed” into the computer memory and is used by the processor in real-time to generate the control signals. The control algorithm in such a controller can be modified simply by reprogramming, without the need for hardware changes. Typically, data are sampled into a digital controller at a fixed sampling period. This chapter will present relevant issues of data sampling. A convenient way to analyze and design digital control systems is by the z-transform method. The theory behind this method will be presented and issues such as stability analysis and controller/ compensator design by the z-transform method will be described.
