Odometer-aided visual-inertial SLAM systems typically have a good performance for navigation of wheeled platforms, while they usually suffer from degenerate cases before the first turning. In this paper, firstly we perform an observability analysis w.r.t. the extrinsic parameters before the first turning, which is a complement of the existing results of observability analyses. Secondly, inspired by the above observability analyses, we propose a bidirectional trajectory computation method, by which the poses before the first turning are refined in the backward computation thread, and the real-time trajectory is adjusted accordingly. Experimental results prove that our proposed method not only solves the problem of the unobservability of accelerometer bias and extrinsic parameters before the first turning, but also results in more accurate trajectories in comparison with the state-of-the-art approaches.

中文翻译：

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里程表辅助视觉惯性SLAM的双向轨迹计算

里程表辅助的视觉惯性SLAM系统通常在轮式平台导航方面具有良好的性能，而它们通常在首次转弯之前就处于退化状态。在本文中，首先，我们在首次转向之前使用外部参数进行了可观察性分析，这是对现有可观察性分析结果的补充。其次，在上述可观察性分析的启发下，提出了一种双向轨迹计算方法，该方法可以在后向计算线程中细化第一次转弯之前的姿态，并相应地调整实时轨迹。实验结果证明，本文提出的方法不仅解决了初次转向之前加速度计偏差和外在参数无法观测的问题，