Abstract:
In process control industries, automatic controllers are introduced. PID (Proportional-Integral- Derivative) controllers are the workhorses of many industrial controller applications. The commonly used Ziegler Nichols tuning method holds good for a system with small decay ratio and fails when decay ratio is large and tuning is also difficult. IMC tuning rules enhance the control performance by determining one tuning parameter, the filter time constant. The need for improved performance of the process has led to the development of robust and optimal controllers. Genetic (GA) algorithm allows the purpose of the optimized parameters for the controllers. GA performed standard tuning and determine ITAE (Integral Time Absolute Error) performance criterion produces most effective PID controller. In this paper, the objective of the controller design is to maintain the temperature of water in the liquid tank in a desired value. System identification of this nonlinear process is done by empirical method, which is identified to be nonlinear and approximated to be a First Order Plus Dead Time (FOPDT) model. The advanced control algorithm, IMC and GA is designed for this FOPDT process model. GA algorithm is implemented and the performance is compared with the conventional PID and IMC algorithm in terms of performances indices. It is observed that GA for the system provides optimum values of performance indices.

Keywords: PID ZN-II, IMC, GA, System Identification