Journal Article

A Unified Discussion on Signal Filtering in PID Control

Tore Hägglund


The major input signals entering the PID controller are: the setpoint, the process output, and measurable load disturbances. By feeding these signals through suitable filters, the properties of the feedback loop can be improved significantly. The goal of this paper is to provide a unified discussion about these filters. The paper treats set-point handling, feedforward from load disturbances, TITO (two input two output) control, noise filtering, and process dynamics compensation. An industrial case from the steel industry is also presented.


PID control, Feedforward, Filtering, Lead-lag filter, Decoupling, Controller structures


Control Engineering Practice, 21:8, pp. 994–1006, August 2013.