超低空空投非线性PIO预测方法

An Evaluation Method for PIO Trend in the Process of Ultra-Low-Altitude Airdrop

在超低空空投下滑阶段,容易出现驾驶员诱发振荡即PIO(Pilot Induced Oscillation)问题,在此基础上分析了空投下滑拉平阶段产生PIO的主要致因,并建立含作动器速率限制的人机闭环系统,推导了闭环系统PIO发生的公式。基于同步和Neal-Smith驾驶员模型以及不同作动器速率饱和值运用描述函数法和GAP准则预测某型运输机PIO趋势。不同驾驶员模型PIO预测结果不同,同步驾驶员模型比Neal-Smith驾驶员模型仿真效果好,运用同步驾驶员模型进行预测,当驾驶员操纵增益绝对值大于11.5时,人机闭环系统失稳,容易产生PIO问题。仿真结果表明,若PIO是由驾驶员粗暴操纵所致,可通过减小操纵增益有效避免PIO的发生,在合理且允许范围内提高运输机舵机作动速率限制值可在一定程度避免PIO的发生。

In view of the PIO (Pilot-Induced-Oscillation)problem prone to occurrence in ultra-low-altitude airdrop,a closed-loop system with actuator-rate limitation is established,and the formula of PIO of the closed-loop system is deduced.Based on the synchronization and Neal-Smith model and the different actuator saturation values,the descriptive function method and the GAP criterion are used to predict the PIO trend.The results show that the PIO prediction results are different for different pilot models.Compared with the Neal-Smith pilot model,the synchronous control model is more effective,and predicted by the simultaneous control model.When the absolute gain of the driver is greater than 11.5,the closed-loop system is unstable and prone to PIO problems.If the PIO is induced by the pilot,the occurrence of PIO can be effectively avoided by reducing the manipulated gain for the pilot.Within the reasonable and permissible range,The limit value avoids the occurrence of PIO to a certain extent.