Many vehicle platforms typically use sensors such as LiDAR or camera for locally-referenced navigation with GPS for globally-referenced navigation. However, due to the unencrypted nature of GPS signals, all civilian users are vulner-able to spoofing attacks, where a malicious spoofer broadcasts fabricated signals and causes the user to track a false position fix. To protect against such GPS spoofing attacks, Chips-Message Robust Authentication (Chimera) has been developed and will be tested on the Navigation Technology Satellite 3 (NTS-3) satellite being launched later this year. However, Chimera authentication is not continuously available and may not provide sufficient protection for vehicles which rely on more frequent GPS measurements. In this paper, we propose a factor graph-based state estimation framework which integrates LiDAR and GPS while simultaneously detecting and mitigating spoofing attacks experienced between consecutive Chimera authentications. Our proposed framework combines GPS pseudorange measurements with LiDAR odometry to provide a robust navigation solution. A chi-squared detector, based on pseudorange residuals, is used to detect and mitigate any potential GPS spoofing attacks. We evaluate our method using real-world LiDAR data from the KITTI dataset and simulated GPS measurements, both nominal and with spoofing. Across multiple trajectories and Monte Carlo runs, our method consistently achieves position errors under 5 m during nominal conditions, and successfully bounds positioning error to within odometry drift levels during spoofed conditions.

翻译：许多车辆平台通常使用LiDAR或摄像头等传感器进行局部参考导航，同时结合GPS进行全局参考导航。然而，由于GPS信号的未加密特性，所有民用用户都容易受到欺骗攻击——恶意欺骗器会广播伪造信号，导致用户跟踪到错误的位置修正。为防御此类GPS欺骗攻击，研究人员开发了芯片消息鲁棒认证（Chimera）技术，该技术即将在今年晚些时候发射的导航技术卫星3号（NTS-3）上进行测试。但Chimera认证并非连续可用，对于依赖更高频GPS测量的车辆而言，可能无法提供充分保护。本文提出一种基于因子图的状态估计框架，该框架集成LiDAR与GPS信号，同时能够检测并缓解两次连续Chimera认证之间发生的欺骗攻击。该框架将GPS伪距测量与LiDAR里程计结合，提供鲁棒的导航解决方案。基于伪距残差的卡方检测器用于检测并缓解潜在的GPS欺骗攻击。我们利用KITTI数据集中的真实LiDAR数据及模拟GPS测量（包括标称信号与欺骗信号）对方法进行评估。在多个轨迹和蒙特卡洛实验中，我们的方法在标称条件下始终能实现低于5米的位置误差，并在欺骗条件下成功将定位误差限制在里程计漂移水平内。