排序方式: 共有4条查询结果,搜索用时 15 毫秒
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Geiss J. Bühler F. Cerutti H. Eberhardt P. Filleux Ch. Meister J. Signer P. 《Space Science Reviews》2004,110(3-4):307-335
Space Science Reviews - The Apollo Solar Wind Composition (SWC) experiment was designed to measure elemental and isotopic abundances of the light noble gases in the solar wind, and to investigate... 相似文献
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Christian Schlaile Oliver Meister Natalie Frietsch Christoph Keßler Jan Wendel Gert F. Trommer 《Aerospace Science and Technology》2009,13(7):349-357
The use of natural features for vision based navigation of an indoor Vertical-Take-Off-and-Landing (VTOL) Micro Aerial Vehicle (MAV) named Air-Quad is presented. Air-Quad is a small four-rotor helicopter developed at the ITE.Such a helicopter needs reliable attitude information. The measurements of the used MEMS gyroscopes and accelerometers are corrupted by strong noise. To be useful, the MEMS sensors have to be part of an integrated navigation system with aiding through complementary sensors like GPS or the computer vision module presented here.In the computer vision module, feature points are detected and tracked through the image sequence. The relative rotation and translation of the camera are estimated using the two-dimensional motion of the feature points.The three-dimensional points in the scene are modeled with the image coordinates of their first sighting and their inverse depths. Only these inverse depths are estimated for the feature points. An efficient sparse bundle adjustment algorithm is used to improve the estimation of the scene structure and the navigation solution.It is shown that the use of the computer vision module greatly improves the navigation solution compared to a solution based only on MEMS sensors. 相似文献
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C.-V. Meister 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,19(12):1951-1954
Nonlinear calculations of the anomalous electrical conductivity in the plasma of the earth's plasma mantle, the tail plasma sheet boundary layer and the ionospheric F-region density-trough are presented provided that lower-hybrid-drift turbulence exists. It is shown that in these regions the stabilization of the wave growth is mainly caused by current relaxation. Further, the fluctuations of the electrical currents are estimated via Ampère's and Ohm's laws. It is found that the lower-hybrid-drift turbulence causes maximum anomalous collision frequencies of the order of 10−2 Hz in the magnetosphere. The maximum current fluctuations are about 3 10−9 A/m2. The theoretical results are in agreement with ISEE and Prognoz-8 measurements. 相似文献
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Adaptive path planning for VTOL-UAVs 总被引:1,自引:0,他引:1
Meister O. Frietsch N. Ascher C. Trommer G.F. 《Aerospace and Electronic Systems Magazine, IEEE》2009,24(7):36-41
This describes the development of path planning algorithms of a small unmanned four-rotor helicopter. A powerful simulation environment of the whole UAV system - including the characteristics of the important ranging sensors for collision avoidance was developed. This is essential for developing, testing, and verifying of the algorithms. Different collision avoidance strategies for VTOL-UAVs are presented. Enhancements and miniaturization will offer more powerful sensor technologies regarding size, range, and power in the future. Very promising are improvements of sensor modules and new technologies like three-dimensional LASER range-finder, PMD sensors, RADAR range-rmnder, and stereo camera tracking system. Because of the general high level simulation tool introduced herein they can he easily validated and tested without the need and effort of a real hardware implementation. The results showed that adaptive path planning, including collision avoidance, is already applicable on-board small UAV vehicles. With the mentioned new sensor technologies and more calculation power, further improvements like advanced collision notice and global path planning on-board small UAVs are attainable. 相似文献
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