ABSTRACT
This contribution presents a modified autotuning algorithm of the PID controller. The motivation for the modification of the basic autotuning algorithm is to enlarge the class of processes to which it can be applied. The basic autotuning algorithm introduced by Åstrom and Hägglund is extended by the preliminary identification procedure and through the usage of the dead time compensating controller. These modifications are detailed through the description of the algorithms’ functioning. The proposed algorithm has been implemented in the programmable logic controller (PLC) Siemens SIMATIC S7-300. The experimental results confirm the good robustness properties of the proposed algorithm, which were demonstrated in a simulation study.
Key Words. Autotuning, PID control, relay experiment, PLC.
ABSTRACT
The paper deals with the problem of controller design for guaranteed phase margin when the plant include parameter uncertainty. Some results from the area of parametric robust control related to interval systems are combined with the Astrom- Hagglund method to design robust PIDcontroller.
Keywords: Interval systems; Robust control; Astrom-Hagglund method
ABSTRACT
An easy applicable regulator design for stable Linear Time Invariant (LTI) systems with positive controls is presented.The synthesis algorithm is derived on the basis of Lyapunov stability theory and quadratic performance measures.The synthesis algorithm is given as a convex optimization routine,a set of Linear Matrix Inequality (LMI)conditions together with the maximization of some variables.Performance im- provement with respect to the open oop system will be attained,if the oop is closed with the a priori imposed static state feedback control aw,u =max(0 ,Fx ),of which the feedback matrix F has to be determined.Examples are given that illustrate the applicability of the derived synthesis algorithms.More speci .cally,the examples show that costs,i.e.output energy can be reduced and signi .cant disturbance reduction can be achieved.
Key Words.Piecewise Linear Models,Positive Controls,Stabilization,Performance Analysis.
ABSTRACT
New methods for tuning PI controllers for unstable first order plus dead-time (UFOPDT) processes are reported. In contrast to known methods that result on overshoot in the closed-loop response or require the modification of the feedback structure, the pro-posed methods ensure smooth closed-loop response to set-point changes, fast attenuation of step load disturbances and robustness against parametric uncertainty while retaining the classical PI controller structure. This enhanced performance is plausible by the use of a first order set-point filter and by the application of some new accurate approximations of the crossover frequencies of the Nyquist plot for UFOPDT models. The proposed methods require small computation effort and they are particularly useful for on-line applications. Finally, they are favorably compared to the already known PI controller tuning methods.
Keywords: PI controller tuning, process control, unstable processes, dead-time processes.
ABSTRACT
In this paper we will present some procedures for the analytic synthesis,by means of feedforward and feedback standard regulators,of some SISO control systems when the order of the system itself doesn't go beyond the third. These procedures utilize normalized diagrams obtained in [12 ]which supply the relations between the parameters of the above systems and their outputs to canonical inputs. Consequently,these procedures supply,for each of the above systems,proper normalized diagrams which,therefore,can be utilized whatever the numerical values of the parameters are.
Key Words.Analytic synthesis,Standard regulators,PD,PI,Hybrid regulators.