Hesitation and deceleration can communicate yielding
Aliases: deceleration cue · implicit yielding · hesitation cue
What it is
A kinematic yielding cue uses early deceleration, a pause, or slight retreat before an intersection to cede priority to a person. Hesitation here is a legible negotiation move, not control oscillation or localisation failure. It must show both that the robot will not claim the gap and when the person can proceed.
Why it happens
Parties approaching a conflict zone infer priority from relative speed and time to arrival. Early slowing increases the robot's arrival time and provides an observable commitment; stopping is stronger evidence. Late, shallow, or repeated start–stop changes leave priority ambiguous, causing continued waiting or a diagnosis of malfunction rather than courtesy.
Studying it
Deceleration onset and magnitude, pause duration, and restart rule can be manipulated while measuring human entry, reciprocal waiting, path conflict, priority judgement, and misunderstanding. Velocity profiles should be compared at equal closest distance and across traffic density. First encounters and learned repeated encounters need separate reporting.
Where it stops holding
Visual slowing does not guarantee physical stopping on slopes, with high inertia, or on low-friction floors. A long pause may invite several people simultaneously, and crowds obscure the intended recipient. Where local convention does not read deceleration as yielding, orientation, light, or projection must clarify it.
Applying it
- Complete substantial deceleration before the conflict zone and stop without narrowing the pedestrian route.
- Restart only after the intended person clears the zone and newly arrived people are reassessed, not after a fixed timer alone.
- Test single, multiple, and opposing flows, logging first mover, reciprocal waiting, and emergency stops; ask whether slowing meant yielding, failure, or replanning.