Design And Implementation Of Level Control System Based On Immune Genetic Algorithm

PID control is the most common control method used in process control especially in water level control system because of its single algorithm, good robustness and high reliability. Sometimes it is difficult to establish the precise mathematical model in practice, as industry process has non-linearity and time-variety uncertainty. So it cannot attain perfect control effect to use the general PID controller in industry process. Aiming at these questions, people continuously research the methods, which can tune the parameters of the PID controller adapting complex industry status and more exact control demands.Most classic methods can not fit the request to PID parameter robust tuning. So many specialists and scholars begin to study some optimal algorithms to tune PID control parameters, such as the adaptive intelligent controller, the neural net controller, the genetic algorithm controller, etc. The traditional genetic algorithms have a set of quite perfect algorithm system and have been applied in many optimization problems successfully. But there are still some drawbacks, such as lack of local search ability, premature convergence, random walking, etc. which lead to the bad performance in convergence. Recently the studies on biology show that the immune action can hamper the premature and effectively speed up the optimizing. Therefore, the immune principle can give us important edification on how to enhance the performance in the traditional genetic algorithms.This dissertation propose a novel and effective optimization algorithm of PID controller parameters based on Immune Genetic Algorithm(IGA)over the analysis of existing immune theories. This dissertation aims to make the designed algorithm effectively resolve the contradiction between local and global search capability and keep the population diversity during the evolving progress so as to remedy the demerits of traditional GA's. Meanwhile, the experiments on the typical object show that the PID controller based on IGA can accelerate the speed of response and decrease the overshoot. It also has good performance against interfere for parameter variation and good robustness.Additionally, based on the results of simulation, the IGA has also been used in water level control system which is based on Fieldbus for PID controller optimizing. A control and monitor software was implemented on LabVIEW platform. Through the comparative experiment on water level control system, the advance of IGA in PID controller optimizing was improved.