Survey paper: A survey on industrial applications of fuzzy control

http://www.ece.ualberta.ca/~marquez/journal_publications_files/papers/tan_jpc03.pdf

IMC design for unstable processes with time delays

An overview on fault diagnosis and nature-inspired optimal control of industrial process applications

This paper presents a new framework for the design of generic two-degree-of-freedom (2-DOF), linear and fuzzy, controllers dedicated to a class of integral processes specific to servo systems. The first part of the paper presents four 2-DOF linear PI controller structures that are designed using the Extended Symmetrical Optimum method to ensure the desired overshoot and settling time. The second part of the paper presents an original design method for 2-DOF Takagi–Sugeno PI-fuzzy controllers based on the stability analysis theorem. Experimental results for the speed control of a servo system with variable load illustrate the performance of the new generic control structures.

Generic two-degree-of-freedom linear and fuzzy controllers for integral processes

In the paper recent design and tuning methods of PID controllers are summarized briefly. Several decades have seen the widely application of PID controllers and the design and tuning methods have been of considerable development. Process model identification, PID controller structure design, PID parameters tuning methods and the use and expansions of PID are described in turn. PID parameter tuning methods are highlighted.

PID controllers: Design and tuning methods

The methods proposed by Astrom and Hagglund (IFAC Adaptive Control of Chemical Processes, Pergamon Press, New York, 1985, pp. 205–210), Mantz and Tacconi (Int. J. Control 49 (1989) 1465–1471; Ind. Eng. Chem. Res. 20 (1990) 1249–1253) for selection of set-point weighting parameters for stable systems are extended to unstable first-order plus time-delay (FOPTD) systems. Since these methods require the real part of the dominant pole, an analytical solution is derived for calculation of dominant poles of the closed-loop system given the PID controllers settings. For PID controller settings given by DePaor and O'Malley (Int. J. Control 49 (1989) 1273–1284) and Clement and Chidambaram (Chem. Eng. Commun. 62 (1997) 63–74), the set-point weighting parameters are calculated and simple equations are given for the parameters in terms of e (ratio of time delay to dominant time constant). Simulation results on an unstable FOPTD transfer function model and higher-order transfer function model show that the overshoot is significantly reduced by employing the set-point weighting parameters in the PID controller. The performances of the closed-loop servo responses for all the extended methods are compared.

G Prashanti

Papers

Set-point weighted PID controllers for unstable systems