PILOT-INDUCED OSCILLATIONS INVOLVING MULTIPLE NONLINEARITIES

A pilot-induced oscillation is a type of instability caused by dynamic coupling between the pilot and the aircraft. Linear system analysis r eveals that the pilot/aircraft system is unstable during the oscillati on event. However, nonlinearities in the feedback system can limit the response variables so that a sustained, constant amplitude limit cycl e results. A method is presented to analyze the limit cycle behavior o f pilot/aircraft systems as a means of understanding pilot-induced osc illations and their causes. A new computational technique is considere d and a new method of testing limit cycle stability is presented. An a nalysis of the YF-12 pilot induced oscillation characteristics is used to demonstrate the method.