Set-point regulator with blending mechanism

In this paper, a two degree of freedom (2-DOF) control structure with a blending mechanism is proposed. In this new structure, the advantages of one degree of freedom (1-DOF) and 2-DOF control structures are both exploited. This new structure is named as a set-point regulator with blending mechanism (SPR-BM) in which the filtered output of the reference and the pure reference signals are blended so that the overall performance of the system is ameliorated with respect to load disturbance rejection and set-point following. An internal model control (IMC) based PID controller is used as the feedback controller and the blending dynamics are determined with the aim of producing a system output that tries to match to the filtered reference signal. When the controller type is chosen to be a PI, the resulting blending mechanism becomes a pure gain and when it is chosen to be a PID type, the blending mechanism then becomes a first order filter. The proposed SPR-BM structure that has been embedded into the microcontroller is then used to control a high order process with dominant time delay. This real process has been built by putting a process control simulator (PCS 327-Feedback) in series with a heat transfer process trainer (PT 326-Feedback). Finally, the effectiveness of the proposed structure has been demonstrated and compared with classical 1-DOF and 2-DOF structures.