Generalized sector synthesis of reduced-order output feedback controllers for discrete-time servosystems with control input saturation

This paper considers linear time-invariant discrete-time servosystems with control input saturation nonlinearities represented by δ-operator, and proposes a design method of discrete-time output feedback controllers satisfying a regional summational quadratic performance for the systems based on the generalized sector approach. For a given discrete-time servocompensator, the method assumes the output of the nonlinearities to be available for the control, and then it is an integrated design of discrete-time reduced-order dynamic output feedback and anti-windup compensators where each of their orders is the number of available plant states less than the plant order. This paper recasts the design problem using the method as a convex optimization problem based on linear matrix inequalities and linear matrix equations. Furthermore, it is pointed out that the performance achievable by the full-order compensator with the same generalized plant order is exactly the same as that by the reduced-order compensator.