H2/ H∞robust control design for a generalized control structure and flight control application

Abstract

The solution of a generalized H2 optimal control problem is considered where the results apply to one, two and two-and-a-half degrees of freedom controller structures. It is then shown that by choosing a particular robustness cost-weighting term W σ the feedback controller C0 also becomes H∞ optimal. By changing this weighting a compromise between H2 and H∞ properties can be achieved. The resulting combined H2/ H∞ optimal controller minimizes the H∞ norm in a limiting case. The relationship between the H2 and H∞ results is illustrated in a flight control design problem.