This article 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 1) we propose an algorithm to recursively construct safe trajectories by numerically forward propagating the system over a (short) finite horizon, and 2) 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.

中文翻译：

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Gatekeeper：动态环境中非线性系统的在线安全验证和控制


本文介绍了 Gatekeeper 算法，这是一种实时和计算轻量级的方法，可确保非线性系统的轨迹在传感限制下满足安全约束。Gatekeeper 通过引入额外的验证步骤与现有的路径规划器和反馈控制器集成，以确保可以安全地执行建议的轨迹，即使非线性动力学受到有界干扰、输入约束和对环境的部分了解。我们的主要贡献是 1） 我们提出了一种算法，通过在（短）有限范围内以数字方式向前传播系统来递归构建安全轨迹，以及 2） 我们证明跟踪这样的轨迹可以确保系统在未来所有时间（即超出有限视野）保持安全。我们在动态消防任务的模拟以及四旋翼飞行器在在线感知的障碍物环境中导航的物理实验中演示了该方法。我们还提供了针对类似问题的最新技术的比较。