Virtual Closed Loop Identification: A New Method for Low-Order H∞ Controller Design

A new algorithm for H∞ controller order reduction based on virtual closed loop identification is proposed. A high order H∞ controller is implemented in a closed loop system simulation. Subsequently, two sets of input/output data of high order controller in closed loop operation will be attained. By selecting an appropriate filter, these data will be filtered. Afterwards, a low order controller using these data will be identified. Choosing the filter is such that the new low order identified controller will preserve the closed loop performance.