In this paper, we present a fast, lightweight odometry method that uses the Doppler velocity measurements from a Frequency-Modulated Continuous-Wave (FMCW) lidar without data association. FMCW lidar is a recently emerging technology that enables per-return relative radial velocity measurements via the Doppler effect. Since the Doppler measurement model is linear with respect to the 6-degrees-of-freedom (DOF) vehicle velocity, we can formulate a linear continuous-time estimation problem for the velocity and numerically integrate for the 6-DOF pose estimate afterward. The caveat is that angular velocity is not observable with a single FMCW lidar. We address this limitation by also incorporating the angular velocity measurements from a gyroscope. This results in an extremely efficient odometry method that processes lidar frames at an average wall-clock time of 5.8ms on a single thread, well below the 10Hz operating rate of the lidar we tested. We show experimental results on real-world driving sequences and compare against state-of-the-art Iterative Closest Point (ICP)-based odometry methods, presenting a compelling trade-off between accuracy and computation. We also present an algebraic observability study, where we demonstrate in theory that the Doppler measurements from multiple FMCW lidars are capable of observing all 6 degrees of freedom (translational and angular velocity).

翻译：本文提出一种快速、轻量的里程计方法，该方法利用调频连续波（FMCW）激光雷达的多普勒速度测量值，无需进行数据关联。FMCW激光雷达是一种新兴技术，可通过多普勒效应实现每次回波的相对径向速度测量。由于多普勒测量模型相对于6自由度车辆速度呈线性关系，我们可以构建速度的线性连续时间估计问题，随后通过数值积分获得6自由度姿态估计。需要注意的是，单一FMCW激光雷达无法观测角速度。为克服此限制，我们引入陀螺仪的角速度测量值。该方法极为高效，在单线程环境下处理激光雷达帧的平均墙钟时间为5.8毫秒，远低于我们测试所用激光雷达10赫兹的工作频率。我们在实际驾驶序列上展示实验结果，并与最先进的基于迭代最近点（ICP）的里程计方法进行比较，展现了精度与计算量之间的良好平衡。此外，我们通过代数可观测性分析，从理论上证明了多个FMCW激光雷达的多普勒测量值能够观测全部6个自由度（平动速度与角速度）。