This paper presents the gatekeeper algorithm, a real-time and computationally-lightweight method that ensures that trajectories of a nonlinear system satisfy safety constraints despite sensing limitations. gatekeeper integrates with existing path planners and feedback controllers by introducing an additional verification step to ensure that proposed trajectories can be executed safely, despite nonlinear dynamics subject to bounded disturbances, input constraints and partial knowledge of the environment. Our key contribution is that (A) we propose an algorithm to recursively construct safe trajectories by numerically forward propagating the system over a (short) finite horizon, and (B) we prove that tracking such a trajectory ensures the system remains safe for all future time, i.e., beyond the finite horizon. We demonstrate the method in a simulation of a dynamic firefighting mission, and in physical experiments of a quadrotor navigating in an obstacle environment that is sensed online. We also provide comparisons against the state-of-the-art techniques for similar problems.

翻译：本文提出门卫算法，一种实时且计算轻量的方法，确保非线性系统的轨迹在存在感知局限性的情况下仍能满足安全约束。门卫算法通过引入额外的验证步骤，与现有路径规划器和反馈控制器集成，以确保所提议的轨迹能够安全执行，尽管系统存在受有界扰动影响的非线性动力学、输入约束以及对环境的部分认知。我们的核心贡献在于：（A）提出一种算法，通过在（短）有限时域上对系统进行数值前向传播，递归地构建安全轨迹；（B）证明跟踪此类轨迹可确保系统在所有未来时间（即超越有限时域）保持安全。我们在动态消防任务的仿真中，以及四旋翼无人机在在线感知的障碍环境中导航的物理实验中验证了该方法。我们还提供了与针对类似问题的最新技术的比较。