基于通信的列车运行控制(communication based train control,CBTC)系统以其安全、可靠等性能优点在城市轨道交通的运营中得到广泛关注。它通过其核心功能,即为每一列通信列车提供移动授权(movement authority,MA),来实现列车安全间隔...基于通信的列车运行控制(communication based train control,CBTC)系统以其安全、可靠等性能优点在城市轨道交通的运营中得到广泛关注。它通过其核心功能,即为每一列通信列车提供移动授权(movement authority,MA),来实现列车安全间隔运行。针对功能安全和实时性等方面的不足,首先,建立移动授权的层次时间自动机(hierarchical time automaton,HTA)模型,其中嵌入了列车管理、安全位置、遍历障碍物和列车筛选模块,并对模块间的交互信息进行分析;其次,采用巴科斯范式(Backus-Naur form,BNF)语法对其特性进行描述;最后,利用UPPAAL对各特性验证。结果表明,移动授权模型满足实时性、顽健性、可用性、完整性、安全性5项需求,层次时间自动机理论适用于系统需求规范的验证。展开更多
The top relief surfaces of an hourglass worm gear hob are ground manually in the traditional manufacturing process,which cannot ensure the width of the land surfaces of the hob.Moreover,each geometric feature of the h...The top relief surfaces of an hourglass worm gear hob are ground manually in the traditional manufacturing process,which cannot ensure the width of the land surfaces of the hob.Moreover,each geometric feature of the hob has been produced through different manufacturing techniques and machine tools,which results in low efficiency.To solve this problem,we propose a semi-automatic computer aided design(CAD)method for hobs.The point clouds of each feature surface of a hob are calculated by combing mathematical equations of the top relief surfaces built by the proposed method with other existing equations of hob surfaces.According to the point clouds,the method can achieve the automatic modeling for the hob in three-dimensional(3D)software by classifying and extracting the parameter information of the feature-hierarchical knowledge of the hob.Based on the generated 3D model,the entire surfaces of the hob can be manufactured on a four-axis computer numerical control(CNC)milling machine through only twice clamping.Verification of the width of the land surface of the hob manufactured by semi-automatic CAD method on a measuring projector proved the precision of the designed width can be ensured.The edge of the contact area on the worm wheel in a meshing experiment is clear and distinct,which means the worm gear drive is meshed well and the hob manufactured by the proposed method has improved machinability.The method simplifies the processing technique,and improves the design efficiency and production accuracy.展开更多
文摘基于通信的列车运行控制(communication based train control,CBTC)系统以其安全、可靠等性能优点在城市轨道交通的运营中得到广泛关注。它通过其核心功能,即为每一列通信列车提供移动授权(movement authority,MA),来实现列车安全间隔运行。针对功能安全和实时性等方面的不足,首先,建立移动授权的层次时间自动机(hierarchical time automaton,HTA)模型,其中嵌入了列车管理、安全位置、遍历障碍物和列车筛选模块,并对模块间的交互信息进行分析;其次,采用巴科斯范式(Backus-Naur form,BNF)语法对其特性进行描述;最后,利用UPPAAL对各特性验证。结果表明,移动授权模型满足实时性、顽健性、可用性、完整性、安全性5项需求,层次时间自动机理论适用于系统需求规范的验证。
基金supported by The Development of Design and Manufacturing Technology of Double-Enveloping Worm Pair in High-precision with Little Centre Distance(No.69190135)We would like to thank the Professor Workstation of China Agricultural University in Hebei Baoding Laibo Transmission Machinery Manufacturing Co.LTD(No.20200901).
文摘The top relief surfaces of an hourglass worm gear hob are ground manually in the traditional manufacturing process,which cannot ensure the width of the land surfaces of the hob.Moreover,each geometric feature of the hob has been produced through different manufacturing techniques and machine tools,which results in low efficiency.To solve this problem,we propose a semi-automatic computer aided design(CAD)method for hobs.The point clouds of each feature surface of a hob are calculated by combing mathematical equations of the top relief surfaces built by the proposed method with other existing equations of hob surfaces.According to the point clouds,the method can achieve the automatic modeling for the hob in three-dimensional(3D)software by classifying and extracting the parameter information of the feature-hierarchical knowledge of the hob.Based on the generated 3D model,the entire surfaces of the hob can be manufactured on a four-axis computer numerical control(CNC)milling machine through only twice clamping.Verification of the width of the land surface of the hob manufactured by semi-automatic CAD method on a measuring projector proved the precision of the designed width can be ensured.The edge of the contact area on the worm wheel in a meshing experiment is clear and distinct,which means the worm gear drive is meshed well and the hob manufactured by the proposed method has improved machinability.The method simplifies the processing technique,and improves the design efficiency and production accuracy.
