Extremum controller design

An extremum "on-off" controller whose detailed description is given here is designed to continuously operate an industrial process at the extreme value of the process output. The process investigated consists of the following in cascade: a pure time delay, a parabolic function, and a first-order lag. A simple method is presented for selection of the three controller parameters, a gain, a velocity constant, and a dead time. The gain and the velocity constant are chosen so as to obtain a desired average output for the oscillation cycle. The main advantages of the controller designed are speed in reaching the extremum and low sensitivity to disturbances (because of low value of gain). A step-by-step procedure for the control system design is given.