Nonlinear Prefilter to Prevent Pilot-Induced Oscillations due to Actuator Rate Limiting

Abstract

For most modern recorded pilot-induced oscillations (PIOs), for example, YF-22, the flight records show that actuator rate limiting occurred. The root causes of PIOs in which actuator rate limiting occurs are demonstratedthrough simulations, and then a newly developed nonlinear rate limiter prefilter (RLPF) and a software rate limit (SWRL) filter are shown to be useful in preventing the PIO. Motion base simulator and flight-test results show that the RLPF/SWRL filter is successful in preventing departure and/or PIO.