Quan Fenghuan, Liu Shi, Sun Gaofei, Zhang Jian, Zhang Yu, Zhao Bin, Zhang Jierui
Aerospace Ground Simulation Test and Testing Technology Institute, Changchun University of Science and Technology, Changchun 130012, China.
Sensors (Basel). 2024 Jun 26;24(13):4147. doi: 10.3390/s24134147.
Dark-and-weak-target simulators are used as ground-based calibration devices to test and calibrate the performance metrics of star sensors. However, these simulators are affected by full-field-of-view energy nonuniformity. This problem impacts the quality of output images and the calibration accuracy of sensors and inhibits further improvements in navigational accuracy. In the study reported in this paper, we sought to analyze the factors which affect full-field-of-view energy uniformity in dark-and-weak-target simulators. These include uneven irradiation in backlight sources, the leakage of light from LCD display panels, and the vignetting of collimating optical systems. We then established an energy transfer model of a dark-and-weak-target simulator based on the propagation of a point light source and proposed a self-adaptive compensation algorithm based on pixel-by-pixel fitting. This algorithm used a sensor to capture the output image of a dark-and-weak-target simulator and iteratively calculated the response error matrix of the simulator. Finally, we validated the feasibility and effectiveness of the compensation algorithm by acquiring images using a self-built test system. The results showed that, after compensating an output image of the dark-and-weak-target simulator, the grayscale standard display function (SDF) of the acquired sensor image was reduced by about 50% overall, so the acquisition image was more accurately compensated, and the desired level of grayscale distribution was obtained. This study provides a reference for improving the quality of output images from dark-and-weak-target simulators, so that the working environments of star sensors may be more realistically simulated, and their detection performance improved.
暗弱目标模拟器被用作地面校准设备，以测试和校准星敏感器的性能指标。然而，这些模拟器会受到全视场能量不均匀性的影响。这个问题会影响输出图像的质量和传感器的校准精度，并阻碍导航精度的进一步提高。在本文所报道的研究中，我们试图分析影响暗弱目标模拟器全视场能量均匀性的因素。这些因素包括背光源照射不均匀、液晶显示面板的光泄漏以及准直光学系统的渐晕。然后，我们基于点光源的传播建立了暗弱目标模拟器的能量传递模型，并提出了一种基于逐像素拟合的自适应补偿算法。该算法使用传感器捕获暗弱目标模拟器的输出图像，并迭代计算模拟器的响应误差矩阵。最后，我们通过使用自行搭建的测试系统采集图像，验证了补偿算法的可行性和有效性。结果表明，对暗弱目标模拟器的输出图像进行补偿后，采集到的传感器图像的灰度标准显示函数（SDF）总体降低了约50%，因此采集图像得到了更精确的补偿，并获得了所需的灰度分布水平。本研究为提高暗弱目标模拟器输出图像的质量提供了参考，从而可以更真实地模拟星敏感器的工作环境，并提高其探测性能。
