Early Development of Fractional Order Control

Abstract

Early developments of Fractional Order Control (FOC) in 1950s and 60s are presented. It was known that the open-loop transfer function of a good control system shows a fractional order integral form with a fractional order between 1 and 2. Investigation was conducted about the optimum fractional order, the waveform of step response, and the effect of saturation and time delay on it. The result has been used as a design guide for control system of ordinary integer order.