多自由度振动环境下惯组非线性传递特性研究

惯组作为飞行器姿控系统的传感器,其局部安装结构的传递特性的测量精度直接关系到导航精度。目前,惯组普遍使用减振器进行隔振,而减振器都呈现出较强的非线性特征。为了考察惯组在不同工况下的传递特性,将惯组简化为六自由度Duffing模型,推导了基础激励下系统的运动微分方程,并用龙格-库塔法对方程进行求解,分析了自由衰减振动和强迫振动下不同工况的系统传递特性。结果表明,多自由度激励比单自由度激励工况得到的系统传递特性的频率和幅值都低。考虑到惯组真实的使用环境,应当在多自由度振动环境下进行传递特性试验。

Nonlinear transfer characteristics of inertial measurement unit in vibration environment of multi-degrees of freedom

The inertial measurement unit (IMU) is the sensor of the attitude control system. The measurement precision of the transfer characteristics of the IMU directly affects its navigation accuracy. A damper is commonly used for the vibration isolation of the IMU, obviously with nonlinear characteristics. In order to analyze the transfer characteristics of the IMU under various working conditions, this paper simplifies the IMU as a Duffing cubic stiffness model with six degrees of freedom. The differential equations of motion under the base excitation is deduced, and solved by the Runge-Kutta method. The transfer characteristics of the system under free and forced vibration conditions are analyzed. It is shown that the frequency and the amplitude of the system under the working excitation condition of multi-degrees of freedom are lower than that under the excitation of single-degree of freedom. In the working environment of the IMU, the actual test should be carried out in the vibration environment of multi-degrees of freedom.