We present the Field of Safe Motion (FSM), a quantitative safety model for determining whether a driver maintains a collision-free escape route, or "out," at any given moment by accounting for that driver's physical capabilities and the foreseeable actions of other road users. The Field of Safe Travel (FST) provides a framework for representing the types of sensory information and actions available to drivers. However, the FST has remained conceptual in nature since its initial publication almost 90 years ago -- and a concrete computational operationalization is still lacking. At the same time, reachability analysis provides a quantitative basis for assessing the possible actions available to road users, using interpretable kinematic models, but reachability models have so far remained confined largely to the engineering and robotics literature. Bringing these two approaches together provides for an interpretable, quantitative tool for assessing driving behavior across a wide range of driving scenarios. Beyond being interpretable, our approach relies on a relatively small set of basic assumptions that are easy to enumerate and reason about. Furthermore, an interpretable reachability model paired with kinematic assumptions provides a way to bound uncertainty about road users' reasonably foreseeable future locations. We demonstrate the applicability of the FSM to different driving scenarios and discuss the strengths and weaknesses of the model.

翻译：我们提出了安全运动场（FSM），一种通过考虑驾驶员的身体能力及其他道路使用者的可预见行为，来判定驾驶员在任何给定时刻是否保持无碰撞逃生路径（即“出路”）的定量安全模型。安全行驶场（FST）提供了一个框架，用于表示驾驶员可获取的感官信息类型及可采取的行动。然而，自约90年前首次提出以来，FST一直停留在概念层面——目前仍缺乏具体的计算操作化实现。与此同时，可达性分析利用可解释的运动学模型，为评估道路使用者可能采取的行动提供了定量基础，但可达性模型迄今主要局限于工程和机器人学文献。将这两种方法相结合，可形成一种可解释的定量工具，用于评估广泛驾驶场景中的驾驶行为。除了具备可解释性，我们的方法仅依赖于一组易于列举和推理的基本假设。此外，结合运动学假设的可解释可达性模型，为约束道路使用者在合理可预见未来位置的不确定性提供了途径。我们展示了FSM在不同驾驶场景中的适用性，并讨论了该模型的优势与局限。