Improved stable approximants using the Routh array
Vinay Pratap Singh · IEEE Transactions on Automatic Control · 1981
A simple method for obtaining a stable reduced-order (kth-order) approximantG_{k}(s)for a stable hlgh-order (nth-order) transfer functionG(s)is described. The method is an improvement over some previous methods [1], [2] in that it not only ensures matching of the firstktime moments ofG(s)andG_{k}(s), but it also ensures that the (k+1)th time moment ofG_{k}(s)be as close as possible to the corresponding value inG(s).