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为深入认识摩擦对航空相机扫描镜系统频率响应特性的影响,获得更准确描述该系统真实动态的模型,使用随机相位多正弦信号测量了扫描镜系统的频率响应特性并进行了线性近似参数模型辨识。首先,介绍扫描镜系统辨识的实验平台与激励信号选择。然后,使用奇-奇频率随机相位多正弦信号分别测量扫描镜系统在非激励频率处和激励频率处的输出对输入信号幅值的依赖,从而定量评估摩擦非线性的影响。最后,基于信号采样均值及噪声采样方差、协方差估计辨识了扫描镜系统线性近似参数模型。实验结果表明,扫描镜系统的摩擦非线性主要出现在奇频率处,高于噪声10dB;系统的频率响应特性依输入信号幅值不同而各异,在低于20rad/s频率区该差别尤为显著。由于摩擦非线性影响,扫描镜系统需要使用3阶模型描述;与正弦扫描方法相比,基于多正弦信号激励获得的参数模型可更好地描述扫描镜系统真实动态特性。得到的结果为控制器的设计奠定了基础。
In order to understand the influence of friction on the frequency response characteristic of aerial camera scanning mirror system and get a more accurate description of the real dynamic model of the system, the frequency response characteristics of scanning mirror system were measured by using random phase multi-sinusoidal signals and the linear approximation parameter model identification . First of all, introduce the experimental platform of scanning mirror system identification and excitation signal selection. Then, odd-odd frequency random phase multi-sinusoidal signals were used to measure the dependence of the output of the scanning mirror system at the non-excitation frequency and the excitation frequency on the amplitude of the input signal, respectively, to quantitatively evaluate the effect of frictional nonlinearity. Finally, based on the signal sampling mean and noise sampling variance, the covariance estimation is used to identify the linear approximation parameter model of the scanning mirror system. The experimental results show that the frictional nonlinearity of the scanning mirror system mainly occurs at the odd frequency, which is higher than the noise by 10dB. The frequency response of the system varies with the amplitude of the input signal. The difference is especially significant at frequencies below 20 rad / s . Due to the nonlinear effect of friction, the scanning mirror system needs to use the third-order model description. Compared with the sinusoidal scanning method, the parametric model based on multi-sinusoidal signal excitation can better describe the real dynamic characteristics of the scanning mirror system. The results obtained for the design of the controller laid the foundation.