Modeling the Human Pilot Controlling a Rotorcraft with Time-Varying Dynamics

The study summarized herein concerns modeling the human pilot controlling a rotorcraft with time-varying dynamics. The research begins with a computer simulation of a human pilot controlling a simple, single-axis system in which the controlled element dynamics are gradually varied between well-defined, stereotypical systems. A possible mechanism by which the human pilot may be able to quickly ascertain that vehicle dynamics are changing is identified. This initial research led the way for application to a more realistic pilot-in-the-loop application. A six-degree of freedom (rigid body) model of the UH-60 Rascal rotorcraft, with rotor degrees of freedom included is employed. The time variation in vehicle dynamics was created by allowing the Stability and Command Augmentation Systems in the pitch and roll axes to change slowly from rate-command/attitude-hold to attitude-command/attitude hold, similar to the manner in which the controlled-element dynamics were varied in the single-axis study. A "normative" pilot model was created that changes control strategy as the vehicle dynamics vary in a hover position-keeping task in turbulence. Results include a discussion of a methodology for predicting handling qualities and the pilot's ability to detect the presence of added dynamics in the vehicle.