Robust direct georeferencing of lightweight UAV

该子项目的目标是开发能够实时确定轻型飞行器（<5kg）的位置和方向的方法，具有高精度（<1cm, <1°）和高鲁棒性，以便提供直接的地理参考信息。高鲁棒性是实现车辆自主导航的必要条件。利用平台上不同的地图传感器重建地图，对地图的地理参考精度要求很高。因此不需要地面控制点。准确的位置和方向信息也为基于图像的三维重建算法提供了高质量的近似解。实时能力对于自主操作是必要的，并且还允许对地图进行快速的近实时地理参考，以便使飞行计划适应当前情况。由于车辆的尺寸和重量限制，多传感器系统的技术实现以及基于各种传感器模式确定位置和方向的算法的发展是挑战。在工程的第一阶段之后，可以根据预期的规格估计理想条件下的位置和方向。该估计基于GNSS载波相位观测、惯性传感器数据和三轴罗经模块。在飞行过程中进行计算，以便为自主导航过程和三维重建算法提供实时信息。该提案第二阶段的主要目标是通过添加Glonass系统的观测以及GNSS观测条件的位置和环境依赖预测来增强基于GNSS的位置确定。另一个目标是在没有任何或只有少数可用GNSS观测值的情况下增强位置确定。这是通过扩展估计算法来实现的，任何额外的传感器信息，例如来自相机或激光扫描仪，都可以用来弥补这些情况。另一个目标是评估飞行过程中的地理参考精度。

The goal of this subproject is the development of methods, which allow the real-time determination of the position and the orientation of a lightweight aerial vehicle (<5kg) with high accuracy (<1cm, <1°) and high robustness in order to provide direct georeferencing information. A high robustness is necessary for the autonomous navigation of the vehicle. A high accuracy is needed for the georeferencing of the maps, which has been reconstructed from the different mapping sensors on the platform. Therefore no ground control points are needed. The accurate position and orientation information also provide a high quality approximate solution for the image based 3D reconstruction algorithms. The real-time capability is necessary for the autonomous operation and also allows a fast near real-time georeferencing of the maps, in order to adapt the flight plan to the current situation. The challenges are the technical realization of the multi-sensor system due to the size and weight constraints of the vehicle and the development of the algorithms, which determine the position and orientation based on various sensors modalities. After the first phase of the project it is possible to estimate the position and orientation under ideal conditions in accordance with the intended specification. This estimation is based on GNSS carrier phase observations, inertial sensor data and a three axis compass module. The calculation is performed during the flight in order to provide real time information to the process of autonomous navigation and to the 3D reconstruction algorithms.The main goals of the second phase of the proposal are the robustification of the GNSS based position determination by adding observation from the Glonass system as well as the location and environment dependant prediction of the GNSS observation conditions. Another goal is the robustification of the position determination in situations without any or with only a few available GNSS observations. This is done by extending the estimation algorithms in a way, that any additional sensor information, e.g. coming from the cameras or the laserscanner, can be used to bridge these situations. Another goal is the evaluation of the georeferencing accuracy during the flight.