三维升降转台是高海拔宇宙线观测站(Large High Altitude Air Shower Observatory,LHAASO)广角切伦科夫望远镜阵列(Wide Field of View Cherenkov Telescope Array,WFCTA)成像激光雷达标定系统的核心组成部分,主要由慢控子系统(Programm...三维升降转台是高海拔宇宙线观测站(Large High Altitude Air Shower Observatory,LHAASO)广角切伦科夫望远镜阵列(Wide Field of View Cherenkov Telescope Array,WFCTA)成像激光雷达标定系统的核心组成部分,主要由慢控子系统(Programmable Logic Controller,PLC)、机械子系统和标准零点子系统构成,用于精确控制激光束的出射方向。采用高精度数字图像处理技术对三维升降转台的性能进行研究,结果表明,旋转和升降定位精度分别为0.005°和0.056 mm,重复精度分别为0.003°和0.075 mm,满足成像激光雷达标定系统的实验要求。三维升降转台的自动控制巡航功能有效减少了人工干预,提高了系统远程使用的可靠性和效率。标准零点的校准功能可以有效监测三维升降转台的定位精度,并且在失准的情况下能够实现远程校准,确保三维升降转台长期高精度稳定运行。展开更多
The impact of the adaptive cruise control（ ACC）system on improving fuel efficiency is evaluated based on the vehicle-specific power. The intelligent driver model was first modified to simulate the ACC system and it ...The impact of the adaptive cruise control（ ACC）system on improving fuel efficiency is evaluated based on the vehicle-specific power. The intelligent driver model was first modified to simulate the ACC system and it was calibrated by using empirical traffic data. Then, a five-step procedure based on the vehicle-specific power was introduced to calculate fuel efficiency. Five scenarios with different ACC ratios were tested in simulation experiments, and sensitivity analyses of two key ACC factors affecting the perception-reaction time and time headway were also conducted. The simulation results indicate that all the scenarios with ACC vehicles have positive impacts on reducing fuel consumption. Furthermore, from the perspective of fuel efficiency, the extremely small value of the perception-reaction time of the ACC system is not necessary due to the fact that the value of 0.5 and 0.1 s can almost lead to the same reduction in fuel consumption. Finally, the designed time headway of the ACC system is also proposed to be large enough for fuel efficiency, although its small value can increase capacity. The findings of this study provide useful information for connected vehicles and autonomous vehicle manufacturers to improve fuel efficiency on roadways.展开更多
The software of behaviour-based algorithm~ was parted to several functional modules which represented different behaviours with different priorities. A basic algorithm with S-type arbiter and an improved algorithm wit...The software of behaviour-based algorithm~ was parted to several functional modules which represented different behaviours with different priorities. A basic algorithm with S-type arbiter and an improved algorithm with I-type arbiter were compared. The improved algorithm can reduce judging time and avoid some mistakes of the basic one. In mapping obstacles, the robot adjusted the spread angle according to different distances to obstacles in scaled vector field histogram （SVFH） algorithm, and then the robot turned more sharply in near obstacles than in far obstacles, which made the robot move more safely and smoothly in a cluttered room.展开更多
文摘三维升降转台是高海拔宇宙线观测站(Large High Altitude Air Shower Observatory,LHAASO)广角切伦科夫望远镜阵列(Wide Field of View Cherenkov Telescope Array,WFCTA)成像激光雷达标定系统的核心组成部分,主要由慢控子系统(Programmable Logic Controller,PLC)、机械子系统和标准零点子系统构成,用于精确控制激光束的出射方向。采用高精度数字图像处理技术对三维升降转台的性能进行研究,结果表明,旋转和升降定位精度分别为0.005°和0.056 mm,重复精度分别为0.003°和0.075 mm,满足成像激光雷达标定系统的实验要求。三维升降转台的自动控制巡航功能有效减少了人工干预,提高了系统远程使用的可靠性和效率。标准零点的校准功能可以有效监测三维升降转台的定位精度,并且在失准的情况下能够实现远程校准,确保三维升降转台长期高精度稳定运行。
基金The National Natural Science Foundation of China(No.51338003,51478113,51378120)
文摘The impact of the adaptive cruise control（ ACC）system on improving fuel efficiency is evaluated based on the vehicle-specific power. The intelligent driver model was first modified to simulate the ACC system and it was calibrated by using empirical traffic data. Then, a five-step procedure based on the vehicle-specific power was introduced to calculate fuel efficiency. Five scenarios with different ACC ratios were tested in simulation experiments, and sensitivity analyses of two key ACC factors affecting the perception-reaction time and time headway were also conducted. The simulation results indicate that all the scenarios with ACC vehicles have positive impacts on reducing fuel consumption. Furthermore, from the perspective of fuel efficiency, the extremely small value of the perception-reaction time of the ACC system is not necessary due to the fact that the value of 0.5 and 0.1 s can almost lead to the same reduction in fuel consumption. Finally, the designed time headway of the ACC system is also proposed to be large enough for fuel efficiency, although its small value can increase capacity. The findings of this study provide useful information for connected vehicles and autonomous vehicle manufacturers to improve fuel efficiency on roadways.
基金National Natural Science Foundation of China(No.60975059)Leading Academic Discipline Project of Shanghai Municipal Education Commission,China(No.J513032)Innovation Program of Shanghai Municipal Education Commission,China(No.09YZ343)
文摘The software of behaviour-based algorithm~ was parted to several functional modules which represented different behaviours with different priorities. A basic algorithm with S-type arbiter and an improved algorithm with I-type arbiter were compared. The improved algorithm can reduce judging time and avoid some mistakes of the basic one. In mapping obstacles, the robot adjusted the spread angle according to different distances to obstacles in scaled vector field histogram （SVFH） algorithm, and then the robot turned more sharply in near obstacles than in far obstacles, which made the robot move more safely and smoothly in a cluttered room.
