Revisiting the simplified IMC tuning rulesfor low-order controllers: 2DoF feedbackcontroller

This paper revisites the direct synthesis tuning method of continuous-time low-order controllers, and specially PID controllers, for control of time-delayed single-input single-output processes. A setpoint prefilter is included to improve the servo response and integrating load disturbances are accounted for. Robustness is addressed by the feedback controller to obtain the desired maximum sensitivity value. Similar results in step disturbance compensation are obtained with simpler analytical tuning rules when compared to recently reported methods. However, the proposed procedure enables to compensate integrating load disturbances, which are not handled in the other methods.