Online frequency domain identification and genetic tuning of PID controllers

Techniques making use of genetic algorithms are proposed as a means of tuning PID controllers to provide prescribed gain and phase margins. In particular, it is shown that to implement the proposed tuning technique only limited frequency response data is required and that this may be readily obtained from simple online tests using a relay and simple time-delayed control. An illustrative example of the practical application of the method is provided in which a process control system is genetically tuned to a specified gain and phase margin.