为了实现建筑复杂异形构件的自动、快速、分级实体化建模,提出了一种基于三维点云的智能逆向实体化建模方法。以上海音乐厅的科林斯柱头为例,首先,采用双边滤波算法对三维激光扫描仪采集的原始点云数据进行平滑预处理;之后,基于Python...为了实现建筑复杂异形构件的自动、快速、分级实体化建模,提出了一种基于三维点云的智能逆向实体化建模方法。以上海音乐厅的科林斯柱头为例,首先,采用双边滤波算法对三维激光扫描仪采集的原始点云数据进行平滑预处理;之后,基于Python语言的Pymeshlab模块、rhinoscriptsyntax模块、scriptcontext模块对Meshlab和Rhino软件进行了二次开发,依次提出了基于泊松表面重建的三角面片网格生成方法、四边面网格重建方法、非均匀有理B样条(NURBS)多重曲面重建方法;最后,根据实体模型的使用用途,提出了不同精度、不同存储等级、不同数据格式的实体模型自动生成方法。研究表明,该方法显著提高了建筑复杂异形构件实体模型构建效率,节省了传统人工处理模型的时间与成本,可为建筑信息模型(Building Information Modeling,BIM)智能建模、智能预拼装、智能有限元分析等工作提供重要支撑。展开更多
To improve the grinding quality of robotic belt grinding systems for the workpieces with complex shaped surfaces, new concepts of the dexterity grinding point and the dexterity grinding space are proposed and their ma...To improve the grinding quality of robotic belt grinding systems for the workpieces with complex shaped surfaces, new concepts of the dexterity grinding point and the dexterity grinding space are proposed and their mathematical descriptions are defined. Factors influencing the dexterity grinding space are analyzed. And a method to determine the necessary dexterity grinding space is suggested. Based on particle swarm optimization （PSO） method, a strategy to optimize the grinding robot structural dimensions and position with respect to the grinding wheel is put forward to obtain the necessary dexterity grinding space. Finally, to grind an aerial engine blade, a dedicated PPPRRR （P： prismatic R： rotary） grinding robot structural dimensions and position with respect to the grinding wheel are optimized using the above strategy. According to simulation results, if the blade is placed within the dexterity grinding space, only one gripper and one grinding machine are needed to grind its complex shaped surfaces.展开更多
A SIMO(single input and multiple output) system of a step-frequency(SF) radar is used.It works in downward-looking spotlight mode and moves within a 2D synthetic plane array.A 3D(three-dimensional) matrix of bistatic ...A SIMO(single input and multiple output) system of a step-frequency(SF) radar is used.It works in downward-looking spotlight mode and moves within a 2D synthetic plane array.A 3D(three-dimensional) matrix of bistatic scattering fields is produced in both the amplitude and phase from a 3D complex-shaped electric-large target above background surface.In numerical simulation,the bidirectional analytic ray tracing(BART) method is applied to calculate bistatic scattering in the SIMO observations from a volumetric target above background rough surface.An improved 3D RMA(range migration algorithm) is then utilized to make the imaging.Its 3D imaging is applied to reconstruct the target profile.As validation and comparison,the scattering fields of some simple targets are computed with comparisons of the BART and FEKO software.The SIMO techniques of imaging and reconstruction for a 3D target,such as a tank-like model over rough surface,are presented.展开更多
文摘为了实现建筑复杂异形构件的自动、快速、分级实体化建模,提出了一种基于三维点云的智能逆向实体化建模方法。以上海音乐厅的科林斯柱头为例,首先,采用双边滤波算法对三维激光扫描仪采集的原始点云数据进行平滑预处理;之后,基于Python语言的Pymeshlab模块、rhinoscriptsyntax模块、scriptcontext模块对Meshlab和Rhino软件进行了二次开发,依次提出了基于泊松表面重建的三角面片网格生成方法、四边面网格重建方法、非均匀有理B样条(NURBS)多重曲面重建方法;最后,根据实体模型的使用用途,提出了不同精度、不同存储等级、不同数据格式的实体模型自动生成方法。研究表明,该方法显著提高了建筑复杂异形构件实体模型构建效率,节省了传统人工处理模型的时间与成本,可为建筑信息模型(Building Information Modeling,BIM)智能建模、智能预拼装、智能有限元分析等工作提供重要支撑。
基金National Natural Science Foundation of China （51075013） Beijing Natural Science Foundation （4102035）+1 种基金 Fundamental Research Funds for the Central Universities （YWF-10-01-A09） Research Foundation of State Key Laboratory for Manufacturing Systems Engineering （Xi＇an Jiaotong University）
文摘To improve the grinding quality of robotic belt grinding systems for the workpieces with complex shaped surfaces, new concepts of the dexterity grinding point and the dexterity grinding space are proposed and their mathematical descriptions are defined. Factors influencing the dexterity grinding space are analyzed. And a method to determine the necessary dexterity grinding space is suggested. Based on particle swarm optimization （PSO） method, a strategy to optimize the grinding robot structural dimensions and position with respect to the grinding wheel is put forward to obtain the necessary dexterity grinding space. Finally, to grind an aerial engine blade, a dedicated PPPRRR （P： prismatic R： rotary） grinding robot structural dimensions and position with respect to the grinding wheel are optimized using the above strategy. According to simulation results, if the blade is placed within the dexterity grinding space, only one gripper and one grinding machine are needed to grind its complex shaped surfaces.
基金supported by the National Natural Science of Foundation of China (Grant Nos. 60971091 and 41071219)
文摘A SIMO(single input and multiple output) system of a step-frequency(SF) radar is used.It works in downward-looking spotlight mode and moves within a 2D synthetic plane array.A 3D(three-dimensional) matrix of bistatic scattering fields is produced in both the amplitude and phase from a 3D complex-shaped electric-large target above background surface.In numerical simulation,the bidirectional analytic ray tracing(BART) method is applied to calculate bistatic scattering in the SIMO observations from a volumetric target above background rough surface.An improved 3D RMA(range migration algorithm) is then utilized to make the imaging.Its 3D imaging is applied to reconstruct the target profile.As validation and comparison,the scattering fields of some simple targets are computed with comparisons of the BART and FEKO software.The SIMO techniques of imaging and reconstruction for a 3D target,such as a tank-like model over rough surface,are presented.
