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Crosswalk design

CrossWalk#

Role For Crosswalk#

Judgement whether a vehicle can go into a crosswalk and plan a velocity of the start/stop.

crosswalk

Role For Walkway#

tbd.

Activation Timing#

Launches when there is a crosswalk on the target lane.

Limitations#

For Crosswalk#

In order to prevent perception failure, the detection area is limited by using pre-defined areas (deceleration area and stop area). Therefore this module does not respond to pedestrians or bicycles outside these areas.

For Walkway#

tbd.

Inner-workings / Algorithms#

Scene Crosswalk#

The crosswalk module considers the following objects as target objects.

  • pedestrian
  • cyclist
Stop condition#

If any of conditions below is met, the vehicle will stop at stop point.

  • A target object exists in the stop area.
  • A target object in the crosswalk area is predicted to enter the stop area within 3 seconds based on its prediction path.
Decelerate condition#

If any of conditions below is met, the vehicle will decelerate to be 10 km/h at slow point.

  • A target object exists in the deceleration area.

Scene Walkway#

  • TBD

Module Parameters#

Parameter Type Description
crosswalk/stop_line_distance double [m] make stop line away from crosswalk when no explicit stop line exists
crosswalk/stop_margin double [m] a margin that the vehicle tries to stop before stop_line
crosswalk/slow_margin bool [m] a margin that the vehicle tries to slow down before stop_line
crosswalk/slow_velocity double [m] a slow down velocity
crosswalk/stop_predicted_object_prediction_time_margin double [s] time margin for decision of ego vehicle to stop or not
walkway/stop_line_distance double [m] make stop line away from crosswalk when no explicit stop line exists
walkway/stop_margin double [m] a margin that the vehicle tries to stop before walkway
walkway/stop_duration_sec double [s] time margin for decision of ego vehicle to stop

Flowchart#

flow chart is almost the same as stop line.

Known Issues#

Crosswalk#

  • The logic for determining speed should be set more strictly from safety reasons.
  • The deceleration speed from the deceleration area logic is set to a constant value (10 [km/h]), which does not take into account the safety distance from obstacles.

Walkway#

  • If the vehicle exceeds the stop line more than the threshold distance, this module will get stuck in STOP state and will not start moving.
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