某电传操纵飞机的Ⅱ型PIO预测和抑制对策研究

 由伺服作动器速率限制引起的 PIO被称为 型 PIO。采用描述函数方法分析了带有速率限制环节的某机人机系统特性,分析表明,当速率限制发生后,在 Nichols图上,系统幅相特性将出现突跃现象,相位滞后增加、幅值减小,此时系统可能出现极限环振荡,即 PIO。用突跃点的频率及其响应的幅值和相角来预测 型PIO,在飞控系统中引入了软件限制环节来减弱速率限制的不利影响。

ANALYSIS AND PREDICTION OF PILOT-INDUCED OSCILLATION WITH ACTUATOR RATELIMITING OF A FLY-BY-WIRE FIGHTER AND A METHOD FOR ALLEVIATING PIO

A feature of all the recent well\|recorded severe pilot\|induced oscillations (PIOs) is related to the presence of actuator rate limiting. Rate limiting has been shown as a main contributor to triggering the PIOs, which are classified as category II PIO. In this paper, approximate describing functions are introduced to describe the nonlinear feature of rate limiting. And inverse describing function techniques are employed to provide a prediction of the limit cycle or PIO frequency with a modern fly\|by\|wire fighter in the landing task. A new criterion is then used to predict category II PIO and is applied to the above fighter to predict PIO. Application of software rate limiters to the design of the fighter with PIO is demonstrated to prove that the stability and performance are improved.