SimFlake

Unity simulator for the UBC Snowbots rover. It works with the ROS 2 Jazzy stack in RoverFlake2 on Ubuntu 24.04.

Workflow document (internal for rover members): https://docs.google.com/document/d/1W4p3Dt0q54WnVc1O408SYnV7q7jjMJXXKghRvAwRw5M/edit?tab=t.0

Setup (once)

You need Ubuntu 24.04 with ROS 2 Jazzy (RoverFlake2's setup installs it).

git clone https://github.com/UBC-Snowbots/SimFlake.git
cd SimFlake && ./setup.sh

setup.sh installs ros-jazzy-rosbridge-suite (the only ROS package the sim needs). It also offers to install Unity Hub and the exact Unity version the project uses. Then, in Unity Hub: Projects > Add > Add project from disk > SimFlake/rover_sim, and open it.

Using the sim

1. Open a scene in Assets/Scenes. TaskWorlds/WaypointTask has everything; ArmScene is the arm on a table.
2. Press Play. The sim starts rosbridge for you and the top-right of the Game view shows ROS: connected. It uses the ROS setup from your ~/.bashrc, or from the terminal you launched Unity from. You don't need to source anything first.
3. Use it like the real rover:

   python3 tools/sim_check.py --drive        # is everything publishing? drives the rover a bit
   ros2 run teleop_twist_keyboard teleop_twist_keyboard
   ros2 run rover_hmi main_hmi_node          # cmd_vel + arm panel (the sim arm listens on /arm/command, no sim_helper needed)
   rviz2                                     # /camera/image_raw, /scan, /odom ...

Topics, conventions and how the ROS link works are documented in CLAUDE.md.

Adding things

• Unity assets (Asset Store or otherwise): import them into rover_sim/Assets and commit. Everyone gets them on pull.
• URDF robots: copy the ROS description package into Assets/, right-click the .urdf and choose Import Robot from Selected URDF file (VHACD for exact colliders). Then add MotorController / ArmController and sensors.
• New sensors / topics: see "Writing sim code" in CLAUDE.md. It's a few lines with Ros.Advertise / Ros.Subscribe.

Troubleshooting

• "ROS: waiting for rosbridge": check the Console for [rosbridge] lines. Run ./setup.sh if rosbridge is missing, or start it by hand: ros2 run rosbridge_server rosbridge_websocket.
• Topics don't show up in ros2 topic list: your terminal and the sim are on different ROS_DOMAIN_IDs. The sim uses the one from ~/.bashrc (or from the terminal that launched Unity).
• Unity says the project is locked: another Unity instance has it open.