Random Walk Global Planner Baseline

The Random Walk Planner serves as a baseline global planner for stress testing system autonomy. Unlike more informed and intelligent planners, the Random Walk Planner generates a series of random trajectories to evaluate system robustness. Using the map published by VDB, the planner will generate and publish multiple linked straight-line trajectories, checking for collisions along these paths.

The blue line is the global plan generated by the random walk. The yellow line shows the past trajectory followed by the local planner when pursuing the previous random global plans.

Functionality

Upon activation by the behavior tree, the Random Walk Planner will:

1. Generate a specified number of straight-line path segments.
2. Continuously monitor the robot's progress along the published path.
3. Once the robot completes the current path, a new set of paths will be generated.

This loop continues, allowing the system to explore various trajectories and stress test the overall autonomy stack.

Parameters

Parameter	Description
num_paths_to_generate	Number of straight-line paths to concatenate into a complete trajectory.
max_start_to_goal_dist_m	Maximum distance (in meters) from the start point to the goal point for each straight-line segment.
checking_point_cnt	Number of points along each straight-line segment to check for collisions.
max_z_change_m	Maximum allowed change in height (z-axis) between the start and goal points.
collision_padding_m	Extra padding (in meters) added around a voxel's dimensions when checking for collisions.
path_end_threshold_m	Distance threshold (in meters) for considering the current path completed and generating a new one.
max_yaw_change_degrees	Maximum allowed change in angle (in radians) between consecutive straight-line segments to ensure a relatively consistent direction.
robot_frame_id	The frame name for the robot's base frame to look up the transform from the robot position to the world.

Services

Parameter	Type	Description
~/global_plan_toggle	std_srvs/Trigger	A toggle switch to turn on and off the random walk planner.

Subscriptions

Parameter	Type	Description
~/sub_map_topic	visualization_msgs/Marker	Stores the map representation that is output from the world or local map topic; currently using vdb local map.
~/tf	geometry_msgs/TransformStamped	Stores the transform from the robot to the world.

Publications

Parameter	Type	Description
~/pub_global_plan_topic	nav_msgs/Path	Outputs the global plan that is generated from the random walk planner.