Neal-Smith criteria-based H-infinity-modeling technique for assessing pilot rating

The Neal-Smith criteria for assessing handling qualities of highly augmented aircraft are rewritten in terms of H-infinity norms to arrive at a mixed-sensitivity performance index. The pitch attitude control is formulated as a mixed-sensitivity problem, which is solved by the model matching technique in the framework of the H-infinity-control theory to yield H-infinity-optimal pilot models. It is shown that the obtained H-infinity-optimal complementary sensitivity function meets the Neal-Smith criteria so perfectly that the task difficulty is exhibited solely by the H-infinity-optimal pilot models. Surveying all the flight configurations of the Neal-Smith flight test, a method using the maximum gain gradient, and the phase at a particular frequency of the H-infinity-optimal pilot model is proposed to correlate pilot ratings with pilot compensation efforts. (Author)