ABSTRACT
This chapter discusses conversion of a continuous-time model into discrete time and describes embedding delay into the discrete-time system. It presents the popular digital proportional–integral–derivative (PID) design, followed by a discussion on “additional discrete-time controllers” that are unique to the direct discrete-time design path. The PID control is a well-established technique in many industrial applications. Enabled by low-cost, high-speed signal acquisition and processing hardware, digital control has become an important tool for the analysis, design, and implementation of control systems. The discrete-time signals are then processed by a microprocessor to generate the discrete-time control outputs. The digital–analog converter in turn converts the discrete-time sequence into a continuous-time signal, generally by means of a zeroth-order hold circuit. Controllers directly designed from the discrete time usually can tolerate a lower sampling frequency as well. One common method employs relay control to force the feedback system into an oscillation.
