barracuda-navigation

User Guide

Start up docker container: docker compose up [-d]

• -d flag runs container in detached mode

Gracefully shutdown container & remove image: docker compose down --rmi local --remove-orphans

Service Interface

The planner provides a ROS service for path planning:

Service: /plan_path Type: barracuda_msgs/PlanPath

Request:

geometry_msgs/PoseStamped goal_pose

Response:

barracuda_msgs/Waypoints waypoints

Topics

Subscribed Topics

• /robot_pose (geometry_msgs/PoseStamped)

  • Current robot position

• /obstacle_pointcloud (sensor_msgs/PointCloud2)

  • Point cloud representing obstacles in the environment

Published Topics

• /planned_path (barracuda_msgs/Waypoints)

  • The planned path as a series of waypoints

• /planned_path_viz (nav_msgs/Path)

  • Visualization of the planned path for RViz

• /rrt_tree (visualization_msgs/MarkerArray)

  • Visualization of the RRT tree structure

Waypoint Interpolation

The navigation system includes a waypoint interpolation node that converts discrete RRT* waypoints into smooth, high-resolution paths suitable for robot control.

Features

• Smart Interpolation: Uses linear interpolation for 2 waypoints, cubic spline for 3+ waypoints
• Speed Control: Ensures path execution never exceeds maximum safe speeds
• High Resolution: Generates dense waypoint sequences from sparse RRT* output
• Constant Timing: Provides consistent time intervals for smooth controller operation

Parameters

Parameter	Type	Default	Description
~velocity	double	1.0	Base velocity for time parameterization (m/s)
~max_speed	double	2.0	Maximum allowed speed safety limit (m/s)
~base_dt	double	0.1	Controller time step for speed estimation (s)
~output_dt	double	0.02	High-resolution sampling interval (s)

Topics

Subscribed:

• /rrt_waypoints (barracuda_msgs/Waypoints)
  • Sparse waypoints from the RRT* planner

Published:

• /interpolated_path (nav_msgs/Path)
  • High-resolution interpolated path with speed control

How It Works

1. Speed Estimation: Analyzes waypoint distances to estimate maximum speeds
2. Global Scaling: If any segment would exceed max_speed, the entire path timing is scaled proportionally
3. Interpolation: Creates smooth curves (linear or cubic spline) between waypoints
4. High-Resolution Sampling: Generates dense waypoints at constant output_dt intervals
5. Safety: Guarantees speeds remain within limits while maintaining smooth motion

Target Odometry Publisher

The target_odometry_publisher node converts the interpolated_path into a constant-speed target trajectory for downstream controllers (e.g., an LQR). It selects a lookahead waypoint along the path and publishes the corresponding pose and linear velocity as nav_msgs/Odometry.

Node

• Executable: barracuda_navigation/scripts/target_odometry_publisher.py

Subscribed Topics

• interpolated_path (nav_msgs/Path)
• odometry/filtered/global (nav_msgs/Odometry)

Published Topics

• target_odometry (nav_msgs/Odometry)
  • Note: When launched inside the barracuda namespace, the fully-qualified topic appears as /barracuda/target_odometry.

Parameters

Parameter	Type	Default	Description
~path_topic	string	interpolated_path	Input path topic
~odom_topic	string	odometry/filtered/global	Input robot odometry topic
~target_topic	string	target_odometry	Output target odometry topic
~frame_id	string	map	Output frame if path has no frame
~desired_speed	double	0.8	Constant translational speed (m/s)
~lookahead_dist	double	1.5	Lookahead distance along path (m)
~max_lookahead_dist	double	3.0	Cap for lookahead distance (m)
~publish_rate	double	30.0	Publishing rate (Hz)
~hold_at_end	bool	true	Hold final waypoint; publish zero linear velocity within ~hold_distance
~hold_distance	double	0.3	Distance threshold to trigger final hold (m)

Behavior

1. Finds the nearest path index to the current position and enforces forward progress (no backtracking).
2. Chooses a target index where the along-path distance from the nearest index ≥ lookahead_dist (capped by max_lookahead_dist).
3. Publishes:
   • Pose: position with orientation aligned to the 3D path tangent (roll=0, pitch from slope, yaw from XY).
   • Twist (linear): constant speed along the local 3D path tangent (vx, vy, vz); zeroed when holding at the final waypoint.
   • Twist (angular): zeros (attitude control handled by your controller).

Launch

• barracuda_navigation/launch/waypoint_interpolator_demo.launch runs:

  • waypoint_interpolator
  • waypoint_test_publisher
  • target_odometry_publisher

• barracuda_navigation/launch/barracuda_navigation.launch runs:

  • rrt_star_planner
  • target_odometry_publisher

Example (demo):

roslaunch barracuda_navigation waypoint_interpolator_demo.launch

Then monitor:

rostopic echo /barracuda/target_odometry