Digital filtering for high performance real-time control

Nowadays many control systems are implemented digitally, and the controllers which process the feedback signals and generate drive signals for the actuators are essentially IIR digital filters. The characteristics may either be defined as continuous time transfer functions and transformed into a discrete time representation for implementation, or they may be directly defined as discrete transfer functions. Either way the requirements for achieving effective high-performance control have some particular characteristics which it is important to appreciate, and for this reason digital filtering is as much an enabling technology for real-time control as it is for communications systems and other applications with which it is more commonly linked.