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1. A robust sequence image matching algorithm for solving flight position and heading | |||
Ru Jiangtao,Leng Xuefei,Wu Songsen,Mao Xingyun,Gong Zhe | |||
Aviation 19 September 2015 | |||
Show/Hide Abstract | Cite this paper︱Full-text: PDF (0 B) | |||
Abstract:As for the transformations of translation and rotation exist between sequence images in the image matching navigation system, it is hoped that the algorithm can simultaneously solve the position and heading parameters. Therefore, an algorithm for sequence image matching based on Harris corner and modified hausdorff distance was proposed. In this method, the coordinates of the corners are described in both polar coordinates and Descartes coordinates. Considering the rotational invariance of radius set in polar coordinates, Hausdorff distance is used to match radius sets between sequence images. Then, the rotation angle and the translation distance will be calculated. Experimental analysis has been carried out for the influence of different Gauss noise and the number of Harris corner. Results show that images can still be matched with rotation angle of ${0^ circ }$, ${60^ circ }$, and ${90^ circ }$ under Gauss white noise with 0.01 variance while the position error is less than one pixel, heading error is less than 5 degrees, and matching time is about 4 seconds. The algorithm has robustness and can meet the requirements of real-time and accuracy of sequence image matching for navigation system. | |||
TO cite this article:Ru Jiangtao,Leng Xuefei,Wu Songsen, et al. A robust sequence image matching algorithm for solving flight position and heading[OL].[19 September 2015] http://en.paper.edu.cn/en_releasepaper/content/4654929 |
2. Optimal ZEM/ZEV Feedback Guidance for Mars Powered Descent Phase | |||
ZHOU Liuyu,,XIA Yuanqing | |||
Aviation 07 November 2013 | |||
Show/Hide Abstract | Cite this paper︱Full-text: PDF (0 B) | |||
Abstract:This paper applies the zero-effort-miss (ZEM) and zero-effort-velocity (ZEV) optimal feedback guidance algorithm to the Mars powered descent problem. Detailed descriptions have been given to this algorithm. The main advantage of this optimal guidance law is that it can not only meet the final position and velocity requirement at the same time, but also be fuel-optimal. For future Mars landing mission, the thrust-limited engine is most likely to be used. The optimal final time will be studied and determined by simulation which can minimize the fuel usage while ensuring precision landing and no-subsurface constraints. And the optimal sliding-mode guidance(OSG) which is a modification of optimal guidance law(OGL) will also be discussed and compared with the pure optimal guidance law for the Mars powered descent phase. Monte Carlos are run to test the robustness and reliability of the two algorithms which show that the two algorithms can achieve precise landing perfectly and have nearly identical performance in robustness and reliability. | |||
TO cite this article: ZHOU Liuyu,,XIA Yuanqing. Optimal ZEM/ZEV Feedback Guidance for Mars Powered Descent Phase[OL].[ 7 November 2013] http://en.paper.edu.cn/en_releasepaper/content/4568642 |
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