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The freespace_planner#

freespace_planner_node#

freespace_planner_node is a global path planner node that plans trajectory in the space having static/dynamic obstacles. This node is currently based on Hybrid A* search algorithm in freespace_planning_algorithms package. Other algorithms such as rrt* will be also added and selectable in the future.

Note Due to the constraint of trajectory following, the output trajectory will be split to include only the single direction path. In other words, the output trajectory doesn't include both forward and backward trajectories at once.

Input topics#

Name Type Description
~input/route autoware_auto_planning_msgs::Route route and goal pose
~input/occupancy_grid nav_msgs::OccupancyGrid costmap, for drivable areas
~input/odometry nav_msgs::Odometry vehicle velocity, for checking whether vehicle is stopped
~input/scenario tier4_planning_msgs::Scenario scenarios to be activated, for node activation

Output topics#

Name Type Description
~output/trajectory autoware_auto_planning_msgs::Trajectory trajectory to be followed
is_completed bool (implemented as rosparam) whether all split trajectory are published

Output TFs#

None

How to launch#

  1. Write your remapping info in freespace_planner.launch or add args when executing roslaunch
  2. roslaunch freespace_planner freespace_planner.launch

Parameters#

Node parameters#

Parameter Type Description
planning_algorithms string algorithms used in the node
vehicle_shape_margin_m float collision margin in planning algorithm
update_rate double timer's update rate
waypoints_velocity double velocity in output trajectory (currently, only constant velocity is supported)
th_arrived_distance_m double threshold distance to check if vehicle has arrived at the trajectory's endpoint
th_stopped_time_sec double threshold time to check if vehicle is stopped
th_stopped_velocity_mps double threshold velocity to check if vehicle is stopped
th_course_out_distance_m double threshold distance to check if vehicle is out of course
vehicle_shape_margin_m double vehicle margin
replan_when_obstacle_found bool whether replanning when obstacle has found on the trajectory
replan_when_course_out bool whether replanning when vehicle is out of course

Planner common parameters#

Parameter Type Description
time_limit double time limit of planning
minimum_turning_radius double minimum turning radius of robot
maximum_turning_radius double maximum turning radius of robot
theta_size double the number of angle's discretization
lateral_goal_range double goal range of lateral position
longitudinal_goal_range double goal range of longitudinal position
angle_goal_range double goal range of angle
curve_weight double additional cost factor for curve actions
reverse_weight double additional cost factor for reverse actions
obstacle_threshold double threshold for regarding a certain grid as obstacle

A* search parameters#

Parameter Type Description
only_behind_solutions bool whether restricting the solutions to be behind the goal
use_back bool whether using backward trajectory
distance_heuristic_weight double heuristic weight for estimating node's cost

RRT* search parameters#

Parameter Type Description
max planning time double maximum planning time [msec] (used only when enable_update is set true)
enable_update bool whether update after feasible solution found until max_planning time elapse
use_informed_sampling bool Use informed RRT* (of Gammmell et al.)
neighbour_radius double neighbour radius of RRT* algorithm
margin double safety margin ensured in path's collision checking in RRT* algorithm

Flowchart#

uml diagram