Predictive PID

A new stochastic, predictive, proportional-integral-derivative (PID) contro l law is proposed which is mathematically equivalent to generalized predict ive control (GPC) with a steady state weighting term. The main motivation o f this paper is the extension of the classical PID algorithm on industrial computers to do advanced control without employing specialized software. Th e predictive PID constants and the internal model are chosen by equating th e discrete PID control law with the linear form of GPC. The result is a lon g range predictive control law with a model based PID structure. Use of a f irst order model yields a PI controller while a second order plant results in a PID structure. The process model order is restricted to a maximum of t wo although there is no restriction on the choice of GPC tuning parameters. Performance of the predictive PID scheme is shown, via simulation, to be i dentical to GPC. Results from the use of the predictive PID algorithm for t he control of an industrial heat exchanger are also presented. (C) 1999 Els evier Science Ltd. All rights reserved.