Surround Obstacle Checker

Purpose

surround_obstacle_checker is a module to prevent moving if any obstacles is near stopping ego vehicle. This module runs only when ego vehicle is stopping.

Inner-workings / Algorithms

Flow chart

Algorithms

Check data

Check that surround_obstacle_checker receives no ground pointcloud, dynamic objects and current velocity data.

Get distance to nearest object

Calculate distance between ego vehicle and the nearest object. In this function, it calculates the minimum distance between the polygon of ego vehicle and all points in pointclouds and the polygons of dynamic objects.

Stop requirement

If it satisfies all following conditions, it plans stopping.

• Ego vehicle is stopped
• It satisfies any following conditions
  1. The distance to nearest obstacle satisfies following conditions
     • If state is State::PASS, the distance is less than surround_check_distance
     • If state is State::STOP, the distance is less than surround_check_recover_distance
  2. If it does not satisfies the condition in 1, elapsed time from the time it satisfies the condition in 1 is less than state_clear_time

States

To prevent chattering, surround_obstacle_checker manages two states. As mentioned in stop condition section, it prevents chattering by changing threshold to find surround obstacle depending on the states.

• State::PASS : Stop planning is released
• State::STOP ：While stop planning

Inputs / Outputs

Input

Name	Type	Description
~/input/trajectory	autoware_auto_planning_msgs::msg::Trajectory	Reference trajectory
/perception/obstacle_segmentation/pointcloud	sensor_msgs::msg::PointCloud2	Pointcloud of obstacles which the ego-vehicle should stop or avoid
/perception/object_recognition/objects	autoware_auto_perception_msgs::msg::PredictedObjects	Dynamic objects
/localization/kinematic_state	nav_msgs::msg::Odometry	Current twist
/tf	tf2_msgs::msg::TFMessage	TF
/tf_static	tf2_msgs::msg::TFMessage	TF static

Output

Name	Type	Description
~/output/trajectory	autoware_auto_planning_msgs/Trajectory	Modified trajectory
~/output/no_start_reason	diagnostic_msgs::msg::DiagnosticStatus	No start reason
~/output/stop_reasons	tier4_planning_msgs::msg::StopReasonArray	Stop reasons
~/debug/marker	visualization_msgs::msg::MarkerArray	Marker for visualization

Parameters

Name	Type	Description	Default value
use_pointcloud	bool	Use pointcloud as obstacle check	true
use_dynamic_object	bool	Use dynamic object as obstacle check	true
surround_check_distance	double	If objects exist in this distance, transit to "exist-surrounding-obstacle" status [m]	0.5
surround_check_recover_distance	double	If no object exists in this distance, transit to "non-surrounding-obstacle" status [m]	0.8
state_clear_time	double	Threshold to clear stop state [s]	2.0
stop_state_ego_speed	double	Threshold to check ego vehicle stopped [m/s]	0.1

Assumptions / Known limits

To perform stop planning, it is necessary to get obstacle pointclouds data. Hence, it does not plan stopping if the obstacle is in blind spot.