Auto-tuning PID controller design using frequency domain approximation

Recently techniques have been developed for the calculation of PID controller gains based on frequency domain approximation using least squares methods. This paper presents methods for auto-tuning PID controllers based on limited frequency response information, using a weighted least squares approximation to a desired open loop transfer function. Automated techniques used for the calculation of this desired open loop transfer function are described, and simulation results of the auto-tuner are presented. It is shown that the auto-tuner performs well, and effectively designs PID controllers in situations where other auto-tuning techniques have not, including the case of mildly oscillatory systems.