Aerospace Systems and Control Laboratory, Korea Advanced Institute of Sciences and Technologies, Daejeon 34141, Korea.
Sensors (Basel). 2020 Apr 22;20(8):2388. doi: 10.3390/s20082388.
Star Trackers are often the most accurate instrument in an Attitude Determination and Control Systems, but often present a slow update rate, requiring additional sensor and sensor fusion algorithms to provide a smoother and faster output. However, the available rate gyros are either noisy, or expensive and heavy. The proposed work investigates the feasibility of high-speed star trackers with modern optics, sensors, and computing systems. Firstly, we investigate the sensitivity of an optoelectrical acquisition system stimulated by dim stars, secondly, we propose and evaluate an algorithm designed to operate at high speed and to be compatible with an Field-Programmable Gate Array implementation, before evaluating the performance of the implementation on FPGA. Finally, we debate the usability of such a system, both in terms of compatibility with a mission and CubeSat ecosystems, and in terms of performance. As a result, aside from removing the need for a rate gyro, Attitude Determination and Control Systems overall pointing performances can be increased. The proposed attitude determination system achieved a 0.001° accuracy, with a 99.1% sky coverage and an ability to reject false-positive while performing a single-frame lost-in-space star identification at a 50 Hz update rate with a total delay of 19 ms, including 13 ms.
星跟踪器通常是姿态确定和控制系统中最精确的仪器，但通常更新速度较慢，需要额外的传感器和传感器融合算法来提供更平滑、更快的输出。然而，现有的速率陀螺要么噪声大，要么昂贵且笨重。本研究探讨了利用现代光学、传感器和计算系统实现高速星跟踪器的可行性。首先，我们研究了微光恒星刺激的光电采集系统的灵敏度；其次，我们提出并评估了一种旨在高速运行并与现场可编程门阵列实现兼容的算法；最后，我们评估了该算法在 FPGA 上的实现性能。最后，我们从与任务和立方星生态系统的兼容性以及性能方面讨论了这样的系统的可用性。除了不需要速率陀螺之外，姿态确定和控制系统的整体指向性能也可以提高。所提出的姿态确定系统实现了 0.001°的精度，99.1%的天空覆盖率，并能够在 50 Hz 更新率下进行单次帧太空丢失星识别，同时具有抗误报能力，总延迟为 19ms，其中包括 13ms。
