4. Digital controllers

The control methods developed in the previous paragraphs all relate to a continuous process modeled as such and controlled by a continuous (analog) corrector. They have the advantage of being based on a well-established body of theory, backed up by considerable experimental know-how. Their disadvantage is that they do not really correspond to the digital implementation technology used for today's correctors. This has many advantages, not least reliability, and flexibility in programming algorithms, making it easy to obtain a variety of control laws. In practice, the corrector is usually created by an algorithm implemented on a microcomputer; it receives information on the state of the process only at sampling times, via an analog-to-digital converter (ADC); the result of the calculations is transmitted to a digital-to-analog converter (DAC), which produces a piecewise continuous control...