• 摘要: 光学标记突出锥套圆形结构常被用于无人空中安全对接,然而在强太阳光、高辐射云层,以及锥套遮挡等复杂干扰场景下,锥套识别与位姿估计的准确性大大降低,甚至无法定位。因此,提出了一种基于锥套成像特性的识别与位姿估计方法。首先,基于灯珠成像圆形特征,采用圆形结构元的形态学滤波压制非规则的强太阳光、高辐射云层,增强灯珠信噪比和提取准确度。接着,结合灯珠成像圆度、灯珠之间距离和数量约束等空间特性,以及面积相似性和角度均匀性等锥套光斑簇一致性,删除大量背景干扰,提高锥套识别和抗遮挡准确性。在此基础上,提出基于重投影误差优化PnP (perspective-n-point)算法的位姿估计算法高精度估计锥套位姿和抗遮挡性能。地面锥套实测结果表明,相对于经典方法,该方法显著增强了强太阳光、高辐射密集云层和锥套遮挡等复杂干扰背景下锥套识别和位姿估计精度和抗干扰能力,在距离10 m处距离和方位测量误差分别小于3.5 cm和0.2 cm,而在距离2 m处距离和方位测量误差分别小于0.15 cm和0.10 cm,锥套遮挡面积达到60%时识别准确度高于95%,平均处理耗时为16.0 ms。该方法具备自主空中对接所需的准确性、实时性和场景适应能力,有助于提高自主空中对接成功率。

       

      Abstract: Highlighting the circular structure of the cone-drogue with optical markers is widely used for safe autonomous aerial refueling (AAR) docking. However, the complex interference scenarios such as strong sunlight, high-radiance clouds, and cone-drogue occlusions significantly reduce the accuracy of cone-drogue recognition and pose estimation, and may even prevent reliable localization. To address these complex interference scenarios, a cone-drogue recognition and pose estimation method based on cone-drogue imaging characteristics is proposed. Firstly, the morphological filtering with circular structuring elements is applied to suppress irregular strong sunlight and high-radiance clouds based on the circular imaging features of the LED markers, thereby enhancing the signal-to-noise ratio and the extraction accuracy of the LED markers. Subsequently, the cone-drogue is successfully recognized from a large amount of background interference by combining spatial characteristics such as the circularity of LED markers, inter-marker distances and marker-count constraints, as well as the consistency of the cone-drogue marker cluster (e.g., area similarity and angular uniformity). Finally, a pose estimation algorithm based on perspective-n-point (PnP) optimization with reprojection error minimization is proposed to accurately estimate the cone-drogue pose and enhance its occlusion robustness. Ground-based experimental results on the cone-drogue measurements demonstrate that the proposed method significantly improves the accuracy and anti-interference capability of cone-drogue recognition and pose estimation under complex interference backgrounds such as strong sunlight, high-radiance dense clouds, and cone-drogue occlusion compared to state-of-the-art algorithms. Specifically, the measurement errors of distance and azimuth are less than 3.5 cm and 0.2 cm, respectively, at a distance of 10 m. The measurement errors of distance and azimuth are less than 0.15 cm and 0.10 cm, respectively, at a distance of 2 m. The recognition accuracy exceeds 95% when the cone-drogue occlusion area reaches 60%, with an average processing time of 16.0 ms. The method could be employed in autonomous aerial refueling docking to increase the success rate of AAR operations by virtue of high accuracy, real-time performance, and scene adaptability.