非合作目标在轨服务最终接近段视觉导航算法

A vision navigation algorithm for on-orbit servicing final stage approaching of non-cooperative target

为解决在轨服务最终接近段传统单目视觉相对导航方法受相机视场限制以及非合作航天器无法设置人工靶标的问题,提出了以非合作航天器太阳帆板三角形支架的部分结构为测量目标的视觉相对导航算法.首先,设计了"自拍杆"相机安装结构和相机实时标定方案,给出了视觉相机安装角的计算方法;然后,基于逆投影原理构建满足三角形支架实际空间几何构型约束的优化模型,采用蚁群搜索算法求解特征点的景深,并应用绝对定位方法估计航天器之间的相对位置和姿态;最后,以非合作航天器在轨服务最终2 m^0 m的接近段为背景进行数学仿真,在相对距离小于1 m时,航天器之间的相对位置和相对姿态确定精度分别优于3 mm和0.2°,验证了算法的有效性和可行性.数学仿真结果表明:该相对导航方案可行,导航算法具有较高的精度,且相对导航的精度随着航天器之间的相对距离的逐渐减少而逐渐提高;同时,该算法对投影点测量误差具有较好的鲁棒性,在投影点测量误差较大时仍具有较高的精度.

At the on-orbit servicing final approach stage,the traditional monocular vision navigation method is limited by the camera field of view,and artificial feature markers cannot be placed on the non-cooperative target.To overcome the drawbacks,a vision navigation algorithm based on part of the solar array triangle support of noncooperative spacecraft is proposed.Firstly,a 'selfie stick'camera installation structure and a real-time camera calibration scheme are designed,and then the method of calculating the camera installation angle is provided.Next,the optimization model satisfying the real geometry structure of the triangle support is built based on the adverse projection theory.Then,the ant colony search algorithm is applied to solve the depth and the absolute position method is applied to calculate the relative attitude and position.Finally,the mathematical simulation in the background of on-orbit servicing final 2 m ~ 0 m approaching of non-cooperative spacecraft is carried out.The simulation results show that the relative attitude and position determination accuracy are better than 0.2° and 3 mm when the relative distance is less than 1 m,and it proves that this algorithm is effective and feasible.The simulation results have proven the feasibility of the relative navigation scheme,and indicate that the proposed algorithm has high accuracy,which increases with decreasing relative distance between the servicing and the target spacecraft.Furthermore,the algorithm has good robustness to the measurement errors of projection points,and keeps the accuracy for relative large measurement errors.