Suboptimal model reduction via least-square approximation of time-response by its derivatives and integrals

The reduction of an SISO system is formulated as the minimisation of the l2 criterion. Expansions of a time-response function in terms of its derivatives and integrals are proposed. Approximation of the quadratic criterion reduces the nonlinear determination of the denominator to a simple linear system resolution. An efficient method for evaluation of the required scalar products of repeated integrals and derivatives is proposed.