Some aspects of control loop performance monitoring

In industries where there are a great number of control loops, it would be convenient to have some tool for monitoring the performance of individual loops. This paper starts from one available approach that evaluates the control performance compared to minimum variance control. The authors show, using an example and also from industrial data, that this technique gives an inadequate measure of the performance if the aim is not stochastic control, but step disturbance rejection. Therefore, some modified criteria are proposed and a monitoring tool utilising all available techniques outlined