Application of Gap criterion in prediction of category �� PIO
Meng Jie1, Xu Haojun1, Li Dawei1, Zhang Jiankang2*
1. The Engineering Institute, Air Force Engineering University, Xi’an 710038, China;
2. School of Aeronautic Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, China
To solve advanced fighter flight safety problem caused by category �� PIO (pilot induced oscillations), the Gap criterion was applied to predict category �� longitudinal PIO. The sinusoidal input/triangle output describing function model of rate limiting was built and the Neal-Smith pilot model was improved. The describing function method was proposed to investigate the mechanism of category �� PIO. The stability formula of nonlinear pilot-vehicle system was derived. The calculation method of Gap criterion was attained. The category �� longitudinal PIO sensitivity of a certain fighter was predicted by Gap criterion and the results were verified by time domain simulation. The results prove that Gap criterion has specific physical significance and illustrative results, calculate efficiently, and can predict the occurrence of category �� PIO accurately. The important theoretical references can be provided for designing flight control systems of advanced fighter.
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