Abstract
This paper studies relationships between the polynomial ILQ design method for robust servo systems and two-degree-of-freedom optimal servo systems. It turns out that the former method uses the same state feedback as the latter one, but attains a specified response by letting another tuning parameter large enough. The paper also shows that, because of model matching specification, the polynomial ILQ method needs some additional consideration for guaranteeing optimality. Numerical simulation is carried out to illustrate the results.
