An optimal control approach to pilot/vehicle analysis and the Neal-Smith criteria

An optimal control pilot modeling technique is utilized in the conceptual framework of Neal and Smith who in 1970 presented a closed-loop frequency-domain technique for handling qualities analysis of highly augmented aircraft. By performing their analysis in the alternate manner demonstrated here, an attempt is made to bridge the gap between frequency-domain and time-domain approaches to pilot/vehicle analysis, to introduce what might be considered as a more general pilot modeling approach in this particular application, and thereby move towards extending this approach to even more complex vehicles and piloting tasks. Using the same quadratic cost weightings and set of observations for analyzing a variety of higher-order aircraft dynamics, the optimal control approach was successfully employed in the attempt to duplicate the Neal-Smith results. Specifically, it was found that the optimal control analysis resulted in pilot phase compensation for the configurations studied that were very comparable to those of Neal and Smith. In addition, the analysis here more closely reflected the actual inflight situation in that an actual tracking task was modeled. More importantly, the analysis demonstrated that low closed-loop bandwidth obtained from the analysis correlated well with bandwidth-related problems (i.e., large initial response delays) encountered in flight. This fact could be used as an additional criterion that must be met before considering the characteristics of resonance peak and pilot phase compensation.