Locally optimal-digital redesign of continuous-time systems

The authors present a novel optimal digital redesign technique for finding a dynamic digital control law from the given continuous-time counterpart by minimizing a local quadratic performance index. The quadratic performance index is chosen as the integral of the weighted squared difference between the states of the original closed-loop system and those of the digitally controlled open-loop system at any instant between each sampling period. The developed optimal digital redesign control law enables the states of the digitally controlled open-loop system to match closely those of the original closed-loop system at any instant between each sampling period, and it can easily be implemented using microcomputers with a relatively large sampling period. An illustrative example is presented to demonstrated the effectiveness of the proposed method