NEAL-SMITH CRITERIA-BASED H ∞ -APPROACH TO PREDICTING AIRCRAFT HANDLING QUALITIES

The Neal-Smith criteria for assessing handling qualities of highly augmented aircraft have been transformed into an H∞ -mixed-sensitivity norm. The norm features a control rate related term to account for the roll-off characteristic of the human pilot. The pitch attitude control is formulated as a mixed-sensitivity problem, which is solved by the model matching technique to yield H∞ -optimal pilot models. It is shown that the H∞ -optimal pilot models well characterize the human pilot’s linear control behavior, and the resulting complementary sensitivity function meets the Neal-Smith criteria satisfactorily. Based on this result, a method is proposed to correlate the pilot rating data of the Neal-Smith flight test with the pilot compensation efforts manifested by the H∞ -optimal pilot model. It is shown that a pair of measures from the H∞ optimal pilot model, maximum gain gradient and phase at the bandwidth frequency, can clearly divide the experimental pilot ratings into three levels.