Prediction of Pilot-Induced Oscillations due to Actuator Rate Limiting Using the Open-Loop Onset Point Criterion

Actuator rate limiting has been a causal or contributing factor for Pilot Induced Oscillations (PIO) experienced on highly augmented fighter aircraft. As part of the joint Air Force Institute of Technology-Test Pilot School (AFIT-TPS) program, a critical examination of the Open-Loop Onset Point (OLOP) criterion, developed by DLR German Aerospace, was conducted to see if it could accurately predict PIO due to actuator rate limiting and to evaluate its potential as a design tool. The OLOP criterion was applied to three previous flight test programs involving rate limiting to study its applicability as a design tool.