The FWB filter with real-time detector to suppress category II pilot induced oscillation

PIO (Pilot Induced Oscillation) is the key factor to damage the flight safety and decrease the quality of manned aircraft. Most of modern PIO records associating with rate limiting or position limiting from actuation systems are defined Category II PIO. The existing compensators, e.g. the Feedback-with-Bypass (FWB) filter, can reduced the oscillation potentiality of the pilot-in-the-loop aircraft system due to rate limiting of control surface, however a negative effect evidently arose which slow the response speed of whole system. This paper uses a Real-Time PIO detector based on Short-time Fourier Transform algorithm as a trigger to determine the switch-off time of the compensator working on the whole system so as to suppress the negative effect on responses of system by FWB. Simulation results show us the positive conclusion that this kind combined FWB filter with Real-Time PIO detector is effectively preventing the Category II PIO without performance decreasing.