Intelligent P controller and disturbance observer based PI controller comparison

The paper shows analogies between two separately evolved areas of PID control, the disturbance observer based controllers and the “intelligent” PID controllers. The simplest “intelligent” PID controller is represented by the “intelligent P” controller denoted as iP. It is designed for the simplified “ultra-local” integral plant models neglecting all internal plant feedbacks. These are included and compensated by an equivalent input disturbance. The performance of the iP controller is compared with the controllers employing disturbance observers based on inverted plant model. It is shown that both these solutions may represent an alternatives to the same control strategy.