Reduced-order PIM methods for digital redesign

Complexity increase is common in modern global redesign methods and is tackled in this paper with a specific reference to the concept of plant input mapping. The paper proposes new global digital redesign techniques that rely on linear algebra to constrain the complexity of the resulting sampled-data control system while taking into account the plant dynamics and the topology of the continuous-time (CT) control system, and apply to any stable linear, time-invariant CT control system. Complexity is constrained in two ways. First, each discrete-time (DT) controller transfer function in the loop has an order which is fixed by the designer. Second, the number of DT controllers present in the loop is constrained by the designer. The proposed global digital redesign methods can be readily applied by the control designer as they require neither sophisticated mathematics nor stringent conditions for their application. The effectiveness of the proposed techniques is shown via numerical examples.