Stop line design

Stop Line

Role

This module plans velocity so that the vehicle can stop right before stop lines and restart driving after stopped.

Activation Timing

This module is activated when there is a stop line in a target lane.

Inner-workings / Algorithms

• Gets a stop line from map information.
• insert a stop point on the path from the stop line defined in the map and the ego vehicle length.
• Sets velocities of the path after the stop point to 0[m/s].
• Release the inserted stop velocity when the vehicle stops within a radius of 2[m] from the stop point.

Module Parameters

Parameter	Type	Description
stop_margin	double	a margin that the vehicle tries to stop before stop_line
stop_check_dist	double	when the vehicle is within stop_check_dist from stop_line and stopped, move to STOPPED state

Flowchart

This algorithm is based on segment. segment consists of two node points. It's useful for removing boundary conditions because if segment(i) exists we can assume node(i) and node(i+1) exist.

First, this algorithm finds a collision between reference path and stop line. Then, we can get collision segment and collision point.

Next, based on collision point, it finds offset segment by iterating backward points up to a specific offset length. The offset length is stop_margin(parameter) + base_link to front(to adjust head pose to stop line). Then, we can get offset segment and offset from segment start.

After that, we can calculate a offset point from offset segment and offset. This will be stop_pose.