Improving Learning-based Ego-motion Estimation with Homomorphism-based Losses and Drift Correction

Visual odometry is an essential problem for mobile robots. Traditional methods for solving VO mostly utilize geometric optimization. While capable of achieving high accuracy, these methods require accurate sensor calibration and complicated parameter tuning to work well in practice. With the rise of deep learning, there has been increased interest in the end-to-end, learning-based methods for VO, which have the potential to improve robustness. However, learning-based methods for VO so far are less accurate than geometric methods. We argue that one of the main issues is that the current ego-motion estimation task is different from other problems where deep learning has been successful such as object detection. We define a novel cost function for learning-based VO considering the mathematical properties of the group homomorphism. In addition to the standard L2 loss, we incorporate losses based on the identity, inverse and closure properties of SE(3) rigid motion. Furthermore, we propose to reduce the VO drift by estimating the drivable regions using semantic segmentation and incorporate this information into a pose graph optimization. Experiments on KITTI datasets show that the novel cost function can improve ego-motion estimation compared to the state-of-the-art and the drivable region-based correction further reduces the VO drift.