A new castor wheel mechanism for omni-directional mobile platform is presented. A motion of translation is transformed into a rotation to steer the wheel with the help of a helical path fits into a translation joint a...A new castor wheel mechanism for omni-directional mobile platform is presented. A motion of translation is transformed into a rotation to steer the wheel with the help of a helical path fits into a translation joint and three rollers whose axes are connected to the driving shaft of the wheel. When the path moves in translation it acts on the rollers for steering. The path-roller friction transmission, the wheel kinematics and the maneuverability have been analyzed.展开更多
Virtual simulation technology is of great importance for the teleoperation of lunar rovers during the exploration phase, as well as the design of locomotion systems, performance evaluation, and control strategy verifi...Virtual simulation technology is of great importance for the teleoperation of lunar rovers during the exploration phase, as well as the design of locomotion systems, performance evaluation, and control strategy verification during the R&D phase. The currently used simulation methods for lunar rovers have several disadvantages such as poor fidelity for wheel-soil interaction mechanics, difficulty in simulating rough terrains, and high complexity making it difficult to realize mobility control in simulation systems. This paper presents an approach for the construction of a virtual simulation system that integrates the features of 3D modeling, wheel-soil interaction mechanics, dynamics analysis, mobility control, and visualization for lunar rovers. Wheel-soil interaction experiments are carried out to test the forces and moments acted on a lunar rover’s wheel by the soil with a vertical load of 80 N and slip ratios of 0, 0.03, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.6. The experimental results are referenced in order to set the parameters’ values for the PAC2002 tire model of the ADAMS/Tire module. In addition, the rough lunar terrain is simulated with 3DS Max software after analyzing its characteristics, and a data-transfer program is developed with Matlab to simulate the 3D reappearance of a lunar environment in ADAMS. The 3D model of a lunar rover is developed by using Pro/E software and is then imported into ADAMS. Finally, a virtual simulation system for lunar rovers is developed. A path-following control strategy based on slip compensation for a six-wheeled lunar rover prototype is researched. The controller is implemented by using Matlab/Simulink to carry out joint simulations with ADAMS. The designed virtual lunar rover could follow the planned path on a rough terrain. This paper can also provide a reference scheme for virtual simulation and performance analysis of rovers moving on rough lunar terrains.展开更多
多路径传输控制协议(multipath TCP,MPTCP)利用设备的多个网络接口传输数据,通过聚合带宽来提高传输效率。在进行路径选择时MPTCP通常使用不相交路径选择算法,由于优先选择负载小的路径,这种贪心策略容易造成网络拥塞和带宽利用率不足...多路径传输控制协议(multipath TCP,MPTCP)利用设备的多个网络接口传输数据,通过聚合带宽来提高传输效率。在进行路径选择时MPTCP通常使用不相交路径选择算法,由于优先选择负载小的路径,这种贪心策略容易造成网络拥塞和带宽利用率不足。轮盘赌轮选择通过概率的方式,在路径选择时加入随机性和动态性,能够克服该贪心策略造成的问题。为此,设计了一种基于轮盘赌轮选择的MPTCP路径选择算法,称作基于轮盘赌轮的MPTCP路径选择(roulette wheel based MPTCP path selection,RWSMPS)。RWSMPS通过软件定义网络(software defined network,SDN)控制器监控和分析网络状态信息,基于轮盘赌轮方式进行子流路径选择,用分组检查将子流分配到路径上,充分利用所有可用路径,并保证路径间的负载平衡。在Mininet平台上的实验证明,相比于广泛使用的等价多路径路由(equal cost multi path,ECMP)算法和链路不相交算法,RWSMPS的吞吐量分别提高了43.9%和41.8%,抖动分别减少了41.6%和40.7%。展开更多
文摘A new castor wheel mechanism for omni-directional mobile platform is presented. A motion of translation is transformed into a rotation to steer the wheel with the help of a helical path fits into a translation joint and three rollers whose axes are connected to the driving shaft of the wheel. When the path moves in translation it acts on the rollers for steering. The path-roller friction transmission, the wheel kinematics and the maneuverability have been analyzed.
基金supported by National Natural Science Foundation of China (Grant No. 50975059, Grant No. 61005080)Postdoctoral Foundation of China (Grant No. 20100480994)+1 种基金Postdoctoral Foundation of Heilongjiang Province, Foundation of Chinese State Key Laboratory of Robotics and Systems (Grant No. SKLRS200801A02)College Discipline Innovation Wisdom Plan of China (111 Project, Grant No. B07018)
文摘Virtual simulation technology is of great importance for the teleoperation of lunar rovers during the exploration phase, as well as the design of locomotion systems, performance evaluation, and control strategy verification during the R&D phase. The currently used simulation methods for lunar rovers have several disadvantages such as poor fidelity for wheel-soil interaction mechanics, difficulty in simulating rough terrains, and high complexity making it difficult to realize mobility control in simulation systems. This paper presents an approach for the construction of a virtual simulation system that integrates the features of 3D modeling, wheel-soil interaction mechanics, dynamics analysis, mobility control, and visualization for lunar rovers. Wheel-soil interaction experiments are carried out to test the forces and moments acted on a lunar rover’s wheel by the soil with a vertical load of 80 N and slip ratios of 0, 0.03, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.6. The experimental results are referenced in order to set the parameters’ values for the PAC2002 tire model of the ADAMS/Tire module. In addition, the rough lunar terrain is simulated with 3DS Max software after analyzing its characteristics, and a data-transfer program is developed with Matlab to simulate the 3D reappearance of a lunar environment in ADAMS. The 3D model of a lunar rover is developed by using Pro/E software and is then imported into ADAMS. Finally, a virtual simulation system for lunar rovers is developed. A path-following control strategy based on slip compensation for a six-wheeled lunar rover prototype is researched. The controller is implemented by using Matlab/Simulink to carry out joint simulations with ADAMS. The designed virtual lunar rover could follow the planned path on a rough terrain. This paper can also provide a reference scheme for virtual simulation and performance analysis of rovers moving on rough lunar terrains.
文摘多路径传输控制协议(multipath TCP,MPTCP)利用设备的多个网络接口传输数据,通过聚合带宽来提高传输效率。在进行路径选择时MPTCP通常使用不相交路径选择算法,由于优先选择负载小的路径,这种贪心策略容易造成网络拥塞和带宽利用率不足。轮盘赌轮选择通过概率的方式,在路径选择时加入随机性和动态性,能够克服该贪心策略造成的问题。为此,设计了一种基于轮盘赌轮选择的MPTCP路径选择算法,称作基于轮盘赌轮的MPTCP路径选择(roulette wheel based MPTCP path selection,RWSMPS)。RWSMPS通过软件定义网络(software defined network,SDN)控制器监控和分析网络状态信息,基于轮盘赌轮方式进行子流路径选择,用分组检查将子流分配到路径上,充分利用所有可用路径,并保证路径间的负载平衡。在Mininet平台上的实验证明,相比于广泛使用的等价多路径路由(equal cost multi path,ECMP)算法和链路不相交算法,RWSMPS的吞吐量分别提高了43.9%和41.8%,抖动分别减少了41.6%和40.7%。
