根据节点坐标和节点连接关系创建三维桁架模型，并用matlab平台将模型数据转成3D打印机可识别的stl文件，用于打印。(The 3D truss model is created based on the node coordinates and the node connections, and the model data is converted to the identifiable STL file of the 3D printer with the MATLAB platform,