An optimal reduction algorithm for linear systems with time delays

A simple method of optimally reducing the order of systems with time delays is proposed. The performance index used for optimization is the integral squared error (ISE) between the original and reduced order model responses. Cheap computation of optimal reduced order models with time delay has hitherto proved abortive as closed-form expressions for the ISE has proved difficult to obtain. Simple controllers parametrized using the reduced model result in excellent performance when implemented on the original model.