Time To Brake (TTB) =================== Description ----------- Please refer to the :doc:`TTM`. Properties ---------- Run-time capability ~~~~~~~~~~~~~~~~~~~ Yes Target values ~~~~~~~~~~~~~ 0.4 s [Tamke2011]_ (selection of a minimal risk maneuver), 1 s [Junietz2018a]_ [Huber2020]_ (threshold for critical) Subject type ~~~~~~~~~~~~ Optimal for road vehicles (automated and human), sub-optimal for VRUs Scenario type ~~~~~~~~~~~~~ Overlapping predicted trajectories for a significant time span in the scenario Inputs ~~~~~~ Static/dynamic objects and their state (pose, shape, etc.) at time t, MM for maneuver 'brake' Output scale ~~~~~~~~~~~~ :math:`\{-\infty\} \cup [0, \infty]`, time (s), ratio scale Reliability ~~~~~~~~~~~ High, under the assumption that collisions can be reliably predicted Validity ~~~~~~~~ High for two-actor scenes, medium for more actors when TTB is evaluated under a fixed perspective, but can be increased by aggregating over all actors as at least for one of them, the TTB will be valid Sensitivity ~~~~~~~~~~~ High, but depends on the DMM: if no collisions are predicted for critical scenarios, sensitivity is reduced Specificity ~~~~~~~~~~~ High for humans, as braking is a key choice in human reaction [Adams1994]_; medium for AVs as non-braking maneuvers can often avoid a critical situation, even if TTB :math:`\leq0` [Adams1994]_ Prediction model ~~~~~~~~~~~~~~~~ Time window ^^^^^^^^^^^ Unbound, but usefulness depends on DMM Time mode ^^^^^^^^^ Linear time