Axmann - Forschungsprojekte

Masterarbeiten (abgeschlossen)

  • Investigation of Maximum Consensus Techniques for Robust Localization
    High integrity localization is a fundamental task for an autonomous driving system. Standard localization approaches are usually accomplished by point cloud registration, which is often based on (recursive) least squares estimation, for example, using Kalman filters. However, due to the susceptibility of least squares minimization to outliers, it is not robust. This thesis focuses on robust localization and aims at the investigation of maximum consensus techniques using LiDAR data. The state-of-the-art maximum consensus approach is evaluated from various perspectives and its shortcomings with respect to straight street scenarios are revealed. Against that, a methodologically optimized normal vector based formulation of maximum consensus is proposed, which uses the distribution of the normal vectors to formulate the accumulator of consensus sets. With doing so, the system is able to achieve a robust localization on all common road conditions. The performances of both approaches are tested and analyzed on a data set containing 1915 epochs. The influence of search parameters is examined with respect to localization accuracy and run time. Results show a considerable improvement of the robustness using the normal vector based formulation.
    Leitung: Axmann, Brenner
    Team: Yimin Zhang
    Jahr: 2021
  • Using Dynamic Objects for Probabilistic Multi-View Point Cloud Registration and Localization
    Registering two point clouds involves finding the optimal rigid transformation that aligns those two point clouds. For a connected autonomous vehicle (CAV), an accurate localization for an `ego’ vehicle can be achieved by registering its point cloud to LiDAR data from other connected `cooperative’ vehicles. This paper utilizes an advanced object detection algorithm to select observation points that are on detected vehicles. As a prerequisite, a general probability distribution (cf. left figure) based on the observation points from all detected vehicles is established. For the registration, in the first step, observation points from a cooperative vehicle are assigned to detected bounding boxes. Then, each set of points belonging to one bounding box is registered to the general probability distribution resulting in a `probability map’. In the second step, the probability map is used as shared information and the point cloud of the ego vehicle is registered to it. Different from the Euclidean distance metric of the Iterative Closest Point (ICP) algorithm and the consensus count metric of the maximum consensus method, a new probability-related metric is proposed for a coarse registration. It is used to provide an initial transformation, which is used afterwards in a registration refinement by ICP. The registration is completely based on the vehicle information in the scene. The algorithm is evaluated on the collective perception data set COMAP. Especially for some scenes that are challenging to existing registration algorithms such as scenes in a traffic jam or in an open space where no efficient overlaps of observed static objects exists. For those scenarios, from the perspective of accuracy and robustness, the algorithm has shown good performance. The left figure shows the general distribution of observation points, while the figure on the right shows the registration result between 'probability map' of cooperative vehicle and Lidar points of ego vehicle.
    Leitung: Brenner, Yuan, Axmann
    Team: Peng Chang
    Jahr: 2021


  • Localization and mapping using maximum consensus
    The long-term goal of this research topic is the creation of a localization and mapping algorithm, which is robust against outliers and disturbances. The research project is embedded in the Research Training Group “Integrity and Collaboration in Dynamic Sensor Networks (i.c.sens)” and primarily aims at improving integrity measures. The research is devided into two steps. In the first step, the localization considering the map as known is examined. In the second step, the problem will be extended treating the map as unknown as well.
    Team: Axmann, Brenner
    Jahr: 2020