考虑非线性因素的阵风减缓系统建模与仿真

Modeling and simulation of gust alleviation system with system nonlinearity

主动阵风载荷减缓系统普遍存在多种非线性特性,它们对系统的动态响应有复杂的影响,导致基于线性系统设计的控制方法无法达到预期的性能或稳定性。针对通用运输类飞机,采用有限元和偶极子网格方法建立了气动弹性模型的状态空间,采用描述函数法建立了控制系统中典型的饱和、延时和迟滞3种非线性模型,提出了含非线性环节的液压作动-气动弹性混合模型,对比分析了不同非线性因素对主动阵风载荷减缓系统的影响。仿真结果表明,系统非线性会引起相位滞后、降低系统动态跟踪特性以致降低阵风减缓效果,严重情况下将引起极限环振荡乃至发散。

The active gust load alleviation systems generally have a variety of nonlinear characteristics,which make the dynamic response of system extremely complicated. The expected performance or stability cannot be achieved by methods based on the linear control theory. In this paper,the state-space of aeroelastic motion equation of general transport aircraft is established by finite element method and doublet lattice method. Three kinds of typical nonlinear models in the control system（i. e. saturation,delay and hysteresis） are established by the description function method,respectively. The hydraulic-aeroelastic comprehensive model with system nonlinearity is presented. According to the models mentioned above,the effects of different nonlinear factors in the active gust load alleviation system is analyzed and discussed. The results show that these system nonlinearities will cause phase lag and degrade system dynamic tracking performance,which can reduce the alleviating ability,even cause limit cycle oscillation and divergence under severe conditions.