LOOP SHAPING AND A ZERO-PLACEMENT TECHNIQUE AS APPLIED TO THE BENCHMARK PROBLEM

A classical and a 'quasi-modern' approach are taken to develop robust control laws for the 1992 ACC benchmark problem of Wie and Bernstein. In both approaches, copious use of loop-shaping a la Bode design is em ployed. The quasi-modern approach reported herein is a zero-placement technique, which is a variant on LQG/LTR. This approach allows for the direct selection of the zeros of the loop transfer function, leading to the desired loop shape. Therefore, undesirable pole-zero cancellati ons may be avoided. The modern and quasi-modern approaches are closely related, and can lead to similar control laws. Though the problem add ressed here is SISO, the zero-placement approach can be used on MIMO s ystems. However, in the case discussed herein, the classically designe d controller has superior performance and stability robustness.