Cascade controller design using controller synthesis

In the case of existence of disturbances in a classical single input single output feedback control system, the controller can take action after the disturbance makes the controlled variable move away from the desired value. On the other hand, a cascade control scheme will take an immediate corrective action by using an inner loop controller. In this paper, the use of controller synthesis to tune both the inner and outer loops of the cascade control system is given. Simulation examples are provided to illustrate the much improved closed loop responses of the proposed cascade control system when compared to some existing cascade control design methods.