Comments on "On a property of compensators designed by the separation principle" /spl lsqb/with reply/spl rsqb/

In the above paper by B. Friedland et al. (ibid., vol.38, no.2, p.370-3 (1993)), a proof is given that, in a control system designed with a full-state observer and state feedback control, the compensator transfer function is the same no matter how the closed-loop poles are distributed between the observer and the controller. The present author points out that a technique is known for computing the observer and controller feedback gains corresponding to all possible distributions of closed-loop poles between the observer and the controller. He further points out that the way the closed-loop poles are distributed can make an important difference to the closed-loop system behavior. In reply, Friedland et al. are grateful for the citation of the two references given and they point out further advantage of the controller-observer implementation.<>