Auto-tuning of PID controllers via extremum seeking

The proportional-integral-derivative (PID) controller is widely used in the process industry, but to various degrees of effectiveness because it is sometimes poorly tuned. The goal of this work is to present a method using extremum seeking (ES) to tune the PID parameters such that optimal performance is achieved. ES is a non-model based method which searches on-line for the parameters which minimize a cost function; in this case the cost function is representative of the controllers performance. Furthermore, this method has the advantage that it can be applied to plants in which there is no knowledge of the model. We demonstrate the ES tuning method on a cross section of plants typical of those found in industrial applications. The PID parameters are tuned based on the results of step response simulations to produce a response with minimal settling time and overshoot. Additionally, we have compared these results to those found using other tuning methods widely used in industry.