RRT Planner (ROS1)

A Rapidly-exploring Random Tree (RRT) implementation in ROS1 for planning a collision-free path from a start position to a goal position in a 2D occupancy grid map.

RRT.Demo.mov

---

Features

• Publishes planned path using nav_msgs/Path
• Visualization of tree growth and path in OpenCV window
• Map loading via map_server
• Customizable parameters via YAML config
• Easily integrates with RViz for visualization

---

Prerequisites

• ROS1 (Melodic or Noetic recommended)
• map_server, rviz, cv_bridge, OpenCV
• Properly sourced ROS workspace with the rrt_planner package

---

How to Run

1. Build the workspace

cd ~/catkin_ws
catkin_make
source devel/setup.bash

2. Launch the system

roslaunch rrt_planner rrt_planner.launch

This will:

• Start map_server to publish the map
• Start rviz with the given config
• Start rrt_planner_node to begin planning

3. Provide Map File

Make sure your map.yaml file and corresponding image (JPG/PGM/PNG) are correctly placed under cfg/. The launch file will load it automatically.

4. Restart the planner

To run the planner again, kill the ROS Node and repeat steps 1 - 3

---

Providing Start & Goal

Use RViz tools:

1. Click 2D Pose Estimate to set the start position
2. Click 2D Nav Goal to set the goal position

---

Configuration

All tunable parameters can be set in cfg/config.yaml:

map_topic: "/map"
init_pose_topic: "/initialpose"
goal_topic: "/move_base_simple/goal"
path_topic: "/path"

max_iterations: 2000
step_size: 30
threshold_distance: 40
draw_tree_delay: 100
enable_visualization: true

You can adjust these values to influence the RRT behavior and visualization.

• max_iterations: The number of iterations the algorithm runs for before termination
• step_size: The maximum incremental distance that a new, random point is placed away from the nearest node in the existing tree
• draw_tree_delay: The delay in milliseconds between each tree update during visualisation
• enable_visualisation: Boolean that toggles whether each step of the RRT algorithm is shown when running. Setting to 'true' shows each step.

---

Visualization

• If enable_visualization: true, tree growth and path are shown in an OpenCV window.
• Tree is drawn in blue, path from start to goal in orange, goal in red, start in green.

---

Topics

• Subscribed:

  • /map (nav_msgs/OccupancyGrid)
  • /initialpose (geometry_msgs/PoseWithCovarianceStamped)
  • /move_base_simple/goal (geometry_msgs/PoseStamped)

• Published:

  • /path (nav_msgs/Path)

---

Debugging Tips

• Use rqt_graph to inspect topic connections
• Add ROS_INFO_STREAM logs for runtime data
• Confirm map_server is correctly loading the map

---

Author

Shawn Chan