Analytical design of two degree-of-freedom decoupling control scheme for two-by-two systems with integrator(s)

An analytical two degree-of-freedom decoupling control scheme for two-by-two systems with integrator(s) is proposed. The approach facilitates explicit tuning for both input tracking and load disturbance rejection design goals. In this new scheme, a novel inverse model-based decoupler is first introduced to eliminate interactions. The set-point tracking controller is then analytically derived based on the decoupled process. The disturbance controller that is responsible for rejecting load disturbances is obtained by proposing the desired transfer function for disturbance rejection. Tuning constraints for the proposed disturbance controller are developed based on system robust stability analysis. Simulation examples are used to illustrate the proposed control scheme. Results from the simulation show that a good performance can be obtained using the proposed control scheme. Moreover, it has been demonstrated that the proposed closed-loop for disturbance rejection can also be utilised to reject ramp-type load disturbances.