基于微多普勒效应的旋翼弦长激光探测方法研究

为实现基于微多普勒效应的旋翼目标激光探测与识别,研究了面目标旋翼对激光回波的调制作用.利用物理光学法中面元散射回波叠加原理,构建了矩形面旋翼的微多普勒激光回波模型.通过仿真,利用时频分析方法提取了异于线目标模型的微多普勒特征.机理分析证实该特征反映弦长即旋翼横向尺寸信息,据此提出了相干探测激光回波的矩形旋翼弦长计算方法.不同展弦比旋翼的回波仿真结果与理论公式吻合较好,验证了该方法的有效性.误差分析表明,与进行单一窗长条件下的短时傅里叶变换相比,利用改变窗长的方法分别提取时间、频率信息可有效减小弦长计算误差至1.58%.该模型可实现对旋翼飞行器弦长尺寸的计算,为进一步的旋翼形状探测识别提供了依据.

Research on Laser Detection Method of Rotor Chord Based on Micro-Doppler Effect

In order to detect and recognize rotors based on laser micro-doppler effect,the modulation of laser echo by rotating area rotor is studied.Micro-doppler echo model of rectangular area rotor is built using the physical optics method of scattering echo superposition.Simulation of laser echo based on this model is completed and the micro-doppler feature different from line target rotor is extracted using timefrequency analysis method.Mechanism analysis confirms that the feature contains lateral size information of rotor.This paper proposes a method to calculate the chord of rectangular rotor through laser echo and verifies this method to be effective through rotor echo simulation of various aspect ratio.Error analysis shows that using the method of changing the window size of short-time Fourier transform (STFT) to extract time and frequency information respectively can reduce the chord length calculation error to 1.58％ compared to single size.This model can realize the calculation of aircraft rotor chord size,providing an important reference for the research of rotor identification.