Star camera system and new software for autonomous and robust operation in long duration flights
Star camera system and new software for autonomous and robust operation in long duration flights
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星型相机系统和新软件可在长时间飞行中实现自主且稳健的操作
DOI：
10.1109/aero.2015.7119013
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Y. Vinokurov
中科院分区：
文献类型：
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作者：
D. Chapman;A. Aboobaker;D. Araujo;J. Didier;W. Grainger;S. Hanany;S. Hillbrand;M. Limon;Amber D. Miller;B. Reichborn;I. Sagiv;G. Tucker;Y. Vinokurov
E和B实验（EBEX）是一种气球载望远镜，旨在探测宇宙微波背景中的极化信号。它于2012年12月/ 2013年1月在南极洲上空完成了为期11天的飞行。EBEX需要10角秒精度用于飞行后数据分析的姿态确定，30角分精度用于飞行过程中的实时姿态控制。用于实现这些指向要求的主要指向传感器是两个冗余恒星相机和两个冗余正交陀螺仪。本文的研究重点是恒星相机。EBEX星相机必须能够抵御长时间气球载环境中可能出现的多种挑战。这些挑战包括白天的天空亮度，明亮的极地中间层云，未编目的卫星，对相机焦点的热效应，以及来自其他机载子系统的异常输入的可能性。在长时间飞行中，低通信带宽限制了用户的实时监控和人工干预。每个恒星相机都由一个装有数码相机、嵌入式计算机、硬盘和各种辅助电子设备的加压容器组成，还有一个光学挡板，用于限制反射和减少大气噪声。我们开发了一个可靠的、线程安全的c++软件应用程序，它可以处理图像的潜在问题，并防止其他子系统中的故障。它采用了广泛的特征选择，具有鲁棒和高效的算法，为长时间的环境做好了最好的准备，并以可靠性为重点进行了开发。这些功能从相对新颖到成熟，其中许多功能最终在最近的EBEX飞行中被证明是至关重要的。我们将报告EBEX星相机及其相关定制软件在具有挑战性条件下的设计、实现、测试和成功的飞行性能。
The E and B Experiment (EBEX) is a balloon-borne telescope designed to probe polarization signals in the cosmic microwave background. It completed an 11 day flight over Antarctica in December 2012 / January 2013. EBEX requires 10 arcsecond accuracy on attitude determination for post-flight data analysis, and 30 arcminute accuracy for real-time attitude control during flight. The primary pointing sensors employed to achieve these pointing requirements are two redundant star cameras and two redundant sets of orthogonal gyroscopes. This paper is focused on the star cameras. The EBEX star cameras must be robust against multiple classes of challenges that may arise in the long duration balloon-borne environment. These challenges include daytime sky brightness, bright polar mesospheric clouds, uncataloged satellites, thermal effects on the camera focus, and the potential for abnormal inputs from other on-board subsystems. Real-time monitoring and manual intervention by the user is limited by the low communication bandwidth on long duration flights. Each star camera consists of a pressurized vessel containing a digital camera, an embedded computer, a hard disk, and various supporting electronics, along with an optical baffle to limit reflections and reduce atmospheric noise. We developed a dependable, thread-safe, C++ software application that can tackle potential issues with the images and defend against failures in other subsystems. It employs a wide selection of features with robust and efficient algorithms to best prepare for the long duration environment, and was developed with a focus on reliability. The features range from relatively novel to well-established, and many of them ultimately proved critical in the recent EBEX flight. We will report on the design, implementation, testing, and successful in-flight performance under challenging conditions of the EBEX star cameras and their associated custom-written software.