好奇号火星车ChemCam-LIBS 光谱数据的定量分析研究

Quantitative analysis research of ChemCam-LIBS spectral data of Curiosity rover

  • 摘要: 传统的偏最小二乘法和支持向量机回归等方法在预测光谱对应的火星车地面标样成分元素含量时往往难以获得较高的精度,并难于进一步优化。针对上述问题,在研究中对高维度光谱信息进行三通道折叠以消除其基体效应,并引入在计算机视觉领域表现不俗的ResNet残差网络结构来提取光谱特征并预测对应主成分含量值。文中将ResNet网络结构中的全连接层去除以避免模型参数快速增长,并将网络最后的Softmax分类子层改为线性整流层以便于进行预测,同时添加了指数学习率衰减和Dropout机制以使模型预测结果具备更高的精度与泛化能力。模型各主要元素含量的预测均方根误差相对于线性支持向量机LinearSVR和深度可分离卷积网络Xception分别平均下降了30%和17%。实验结果表明:采用LIBS技术对ChemCam光谱数据进行主成分元素定量分析时,基于ResNet网络建立的回归模型表现出良好的预测特性。

     

    Abstract: The traditional partial least squares method and support vector machine regression method were often difficult to obtain high accuracy and further optimization in predicting the element content of the ground standard sample of the rover corresponding to the spectrum. To solve the above problems, the three-channel folding of high-dimensional spectral information was carried out to eliminate its matrix effect in the research, and introduced the Residual Network structure (ResNet), which was good in the field of computer vision, to extract the spectral features and predict the corresponding principal component content. In this paper, the full connection layer in ResNET network structure was removed to prevent the sudden increase of model parameters, and the last Softmax classification sublayer of the network was changed into a linear rectification layer for prediction. At the same time, exponential learning rate attenuation and Dropout mechanism were added to make the model prediction results have higher accuracy and generalization ability. Compared with linear support vector machine regression (LinearSVR) and depth separable convolution network Xception, the prediction root mean square error of each main element content of the model decreases by 30% and 17% on average, respectively. The experimental results show that the regression model established by ResNet network shows good prediction characteristics when LIBS technology is used for principal element quantitative analysis of ChemCam spectral data.

     

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