无合作目标激光绝对测距中,远距离、真实表面的后向散射特性机理不明朗,严重影响测距结果,是制约测距技术发展的重要瓶颈.以立铣、平铣、平磨等三种典型实际机械加工方式下的粗糙表面为研究对象,测量了在1 550 nm红外激光照射下形成的后向散射场,探究了不同加工方式下特殊后向散射场形成的原因,深入分析了表面纹理、入射方位角、入射角度、粗糙度对后向散射场分布的影响.实验结果分析表明,加工制造表面的后向散射光谱形态分布受加工方式的影响很大,且相互入射几何关系和粗糙度对每种加工方式下的实际粗糙表面均有规律性影响.为了能够获取足够的后向散射能量,对表面参数的识别反演显得十分重要.进一步构建了一种加工表面多维参数反演模型,采用另外一种加工方式(刨床)的样块数据进行验证,加工方式能够被准确区分,入射方位角和粗糙度反演的相对误差分别达到1.21%和1.03%,反演精度较高.经实验验证,通过表面参数的反演极大拓宽了无合作目标激光绝对测距的范围,有效降低了表面纹理、入射方位角、粗糙度等对测距范围的影响.这一研究结果还对具有纹理特征加工表面的后向散射光谱的研究和在其他领域的应用均具有一定的参考价值.

For no cooperation target laser ranging,the backscattering properties of the long-range and real machined surfaces are uncertain which seriously affect the ranging accuracy.It is an important bottleneck restricting the development of no cooperation ranging technology.In this paper,the backscattering characteristics of three typical machining surfaces(vertical milling processing method,horizontal milling processing method and plain grinding processing method) under the infrared laser irradiation with 1 550 nm were measured.The relation between the surface machining texture,incident azimuth,roughness and the backscattering distribution were analyzed and the reasons for different processing methods specific backscattering field formed were explored.The experimental results show that the distribution of backscattering spectra is greatly affected by the machined processing methods.Incident angle and roughness have regularity effect on the actual rough surface of each mode.To be able to get enough backscattering,knowing the surface texture direction and the roughness of machined metal is essential for the optimization of the non-contact measurement program in industry.On this basis,a method based on an artificial neural network(ANN) and genetic algorithm(GA),is proposed to retrieve the surface multi-parameters of the machined metal.The generalized regression neural network(GRNN) was investigated and used in this application for the backscattering modeling.A genetic algorithm was used to retrieve the multi-parameters of incident azimuth angle,roughness and processing methods of machined metal surface.Another processing method of sample(planer processing method) was used to validate data.The final results demonstrated that the method presented was efficient in parameters retrieval tasks.This model can accurately distinguish processing methods and the relative error of incident azimuth and roughness is 1.21% and 1.03%,respectively.The inversion accuracy is high.It can reduce the impact of surface texture,the incident azimuth and incidence angle to the ranging scope.The experiments proved that the inversion of the surface parameters greatly broadened the ranging scope in no cooperation target laser ranging.Taking the Vertical milling sample with roughness Ra=6.3 μm for example,the measuring range can be increased by about 22 m when the incidence angle is increased in the incidence plane which is vertical to the surface texture.The study results of this paper have a certain reference value to the research of the backscattering of machined surface and its application in other areas.