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Try Topological Navigation in Your Browser

ROSCon UK 2026, workshop "ROS in the Field"

Slide deck

https://github.com/LCAS/topological_navigation/wiki/ROSCon-UK-2026

Topological Navigation

This page lets you run the complete topological navigation stack, with a simulated robot on a real farm map, in a GitHub Codespace. You need a web browser and a free GitHub account. Nothing is installed on your own machine, and no robot is needed.

You will:

  1. start a Codespace from the roscon26 branch of this repository,
  2. launch the stack with one command, and
  3. click on the map in your browser to send the robot to a node.

Open in GitHub Codespaces

(you are advised to use a "4-core" Machine Type for better performance)

Direct link: https://codespaces.new/LCAS/topological_navigation/tree/roscon26

Repository and branch: https://github.com/LCAS/topological_navigation/tree/roscon26

1. Start the Codespace

  1. Open the link above and sign in to GitHub if asked.
  2. Check that the branch shown is roscon26, then choose Create new codespace. If you start from the repository page instead, use Code, then the Codespaces tab, then ..., then New with options, and pick the roscon26 branch.
  3. Wait while the environment is built. The first start takes several minutes, because it prepares a ROS 2 Jazzy container with RViz and all dependencies and builds the workspace. Start it before you need it.
  4. When VS Code appears in your browser, this page opens automatically. Open a terminal with Terminal, New Terminal (or press Ctrl+`).

The terminal starts in /workspace/src (this repository). ROS 2 and the pre-built workspace are already sourced in every new terminal.

About cost and tidying up. Codespaces use your own GitHub account's monthly free allowance; see GitHub's billing page for the current figures. A Codespace stops by itself after a period of inactivity. When you are finished, stop or delete it at https://github.com/codespaces so that it does not use up storage or hours.

Alternative: run it locally in VS Code

If you prefer not to use Codespaces, you can run the same environment in VS Code on your own machine.

You need: Docker (running), VS Code with the Dev Containers extension, and Git.

  1. Clone the roscon26 branch and open it in VS Code: 
    git clone -b roscon26 https://github.com/LCAS/topological_navigation.git
code topological_navigation
  2. When VS Code offers Reopen in Container, accept. Otherwise press F1 and run Dev Containers: Reopen in Container.
  3. Wait for the container to build. The first build takes several minutes, and later starts are much faster.
  4. Open a terminal in VS Code (Terminal, New Terminal). It runs inside the container, in /workspace/src, with ROS 2 sourced.
  5. Continue with step 2 below. The ports are forwarded to your machine:
    • web app: http://localhost:8083/
    • RViz desktop (novnc): forwarded port 5801; open it from the Ports tab if the address does not work directly.

If a forwarded port does not respond, remove and re-add it in the Ports tab as described under Troubleshooting.

Alternatively, to use your local VS Code with a Codespace that is already running, install the GitHub Codespaces extension, press F1, run Codespaces: Connect to Codespace, and pick it. The ports are then forwarded to localhost as well.

2. Launch the stack

In the terminal:

ros2 launch topological_navigation topological_navigation.launch.py

RViz starts by default and is available on the noVNC desktop at port 5801. If your Codespace has limited resources (for example, a 2-core machine), you can disable RViz by adding rviz:=false to the launch command.

This starts, in order:

Component What it does
Map manager Loads the Riseholme farm map (92 nodes) and publishes it
Localisation Works out the current and closest node from the robot pose
Fake Nav2 and virtual robot Stand in for the real navigation stack and robot
Topological navigation server Plans routes over the graph and runs the action on each edge
RViz Visualises the map and robot on the noVNC desktop (port 5801)
Web app Browser interface on port 8083
RViz Visualisation, shown on the remote desktop on port 5801

The virtual robot starts on the Office node. Leave this terminal running. Stop everything with Ctrl+C.

3. Open the web app and RViz

Open the Ports tab at the bottom of VS Code. Two ports are forwarded:

Port Label What it shows
8083 Topological Navigation web app The browser interface: the map, the robot, and the controls to send goals
5801 novnc A remote desktop in your browser, showing RViz with the map, the robot and the planned route

For each, click the globe icon (Open in Browser) in its row, or copy the forwarded address into a new browser tab. The notification that appears when the stack starts offers the same.

Keep both ports private (the default). The web app has no authentication, so anyone who could open it could move your robot.

4. Things to try

  • Explore the map. Zoom with the mouse wheel, drag to pan, use Fit map and Centre on robot. Hover over a node to see its pose, its outgoing edges with their actions, and its properties. Compare the properties of different nodes and edges to see what metadata the map carries.
  • Send the robot. Click the node QC, then confirm. The planned route turns orange, the edge being traversed turns red, and the dark disc with an arrow is the robot.
  • Go further, then cancel. Send the robot to t1-a1-cz (the far end of a row), and press Cancel goal half way.
  • Use the command line. Open a second terminal and send a goal. The browser follows along: 
    ros2 action send_goal /topological_navigation \
    topological_navigation_msgs/action/GotoNode "{target: 'WayPoint10'}"
  • Open a second browser tab. Every tab shows the same robot, goal and route, because all state lives in the backend.
  • Watch RViz alongside the web app. Open the forwarded port 5801 (labelled novnc) in a second tab to see the remote desktop with RViz, and compare it with the web app while the robot moves.
  • Change the map. Copy the example map, edit a node property or an edge action, and launch with your copy: 
    cp topological_navigation/test/fixtures/riseholme.tmap3.yaml my_map.tmap3.yaml
ros2 launch topological_navigation topological_navigation.launch.py \
    map_path:=/workspace/src/my_map.tmap3.yaml
    The edge actions (row_traversal, navigate_through_poses) and their behaviour trees are defined in topological_navigation/config/topological_navigation_config.yaml, which the launch file loads by default (argument navigation_config_file).

Useful launch arguments (all optional):

Argument Default Meaning
map_path Riseholme map google maps Absolute path to a .tmap2.yaml or .tmap3.yaml map
rviz true Start RViz (shown on the noVNC desktop, port 5801); use rviz:=false to switch it off
web_app true Start the web app
web_app_port 8083 Port of the web app
robot_speed 1.5 Simulated speed in m/s
initial_x, initial_y, initial_yaw 25.75, 2.8, 0.0 Where the virtual robot starts (the Office node)

5. Edit code and rebuild

The repository is mounted at /workspace/src. After changing code, rebuild with the build alias and re-source the workspace:

build

Troubleshooting

Symptom What to check
Port 8083 or 5801 shows 502 Bad Gateway (or another error) See "Forwarded ports show a 502 error" below
Nothing appears on port 8083 Is the launch command still running in a terminal? Look for errors in its output, then reload the page
RViz does not appear on port 5801 Check that the stack was launched without rviz:=false, then reload the noVNC tab
The map shows but clicking a node does nothing Run ros2 action list in a second terminal. /topological_navigation should be listed. If not, restart the launch
The page looks stale Reload the browser tab; the live connection reconnects by itself
The environment build failed Choose Codespaces: View Creation Log from the command palette (F1) and send us the end of the log
"Port already in use" An earlier launch is still running. Stop it with Ctrl+C, or use web_app_port:=8090

Forwarded ports show a 502 error

If the page for port 8083 (web app) or 5801 (novnc, the RViz desktop) shows 502 Bad Gateway, the port forwarding has gone stale. Remove and re-add the ports:

  1. Make sure the launch command from step 2 is running in a terminal.
  2. Open the Ports tab, right-click each of the rows for 8083 and 5801, and choose Stop Forwarding Port (or click the bin icon).
  3. Click Forward a Port, type 8083, and press Enter. Repeat for 5801.
  4. Open each port again with the globe icon. Optionally set the labels back to Topological Navigation web app (8083) and novnc (5801) with right-click, Set Port Label.
  5. Keep both ports private. If a 502 persists on 5801, right-click the port, choose Change Port Protocol, and try HTTPS instead of HTTP (or the other way round).

Video

toponav-demo-hd.mp4

Learn more