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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2010, Vol. 31 ›› Issue (9): 1701-1707.

• Fluid Mechanics and Flight Mechanics •     Next Articles

A Comparison of Feedback and Foreback Schemes to Prevent Category Ⅱ PIO

Meng Jie1, Xu Haojun1, Zhang Jiankang2   

  1. 1. The Engineering Institute, Air Force Engineering University2. The Complex Systems Fourth Laboratory, Equipment Academy of Air Force
  • Received:2009-10-29 Revised:2010-06-07 Online:2010-09-25 Published:2010-09-25
  • Contact: Xu Haojun

Abstract: When rate limiter is saturated, the additional time delay would occur. It could deteriorate aircraft flying quality and cause category Ⅱ pilot-induced-oscillations(PIO). The rate-limited feedback(RLF) and the dead area stability augmentation(DASA) schemes prevent the category Ⅱ PIO from occurring. The open loop phase compensation capability of two schemes is studied based on describing functions method. The parameter optimization method of RLF scheme is provided. The influence of deadzone and filter parameters on DASA scheme phase compensation capability is analyzed. The responses of two schemes to sine wave input and bias input are examined. The pilot-vehicle system model with rate limiter is developed. The generation mechanism of category Ⅱ PIO is analyzed and the expression to avoid category Ⅱ PIO is derived. The continuous signal phase compensation method is applied to preventing category Ⅱ PIO. The step, discrete and sine tracking tasks which are easy to induce PIO are simulated, and the prevention capabilities of two schemes are compared. The results demonstrate that the RLF scheme has better capability for avoiding category Ⅱ PIO and decreases the occurrence possibility of category Ⅱ PIO.

Key words: flight control systems, pilot induced oscillations, describing functions, actuators, rate-limit

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