DESIGN OF PARALLEL CASCADE CONTROL FOR DISTURBANCE-REJECTION

A new approach is presented to overcome load disturbance problems. Based on the parallel cascade control structure, the primary controller is designed for the servo response, and the secondary controller is designed for the disturbance-rejection purpose. A perfect disturbance-rejection controller is derived for the secondary loop. A new interaction measure for load disturbance (γ) is proposed to determine whether improved load responses is achievable using cascade control structure. More importantly, the interaction measure also quantifies the margin of improvement that can be achieved over conventional single-loop control.