Simulator

The [sim] extra ships a MuJoCo-backed physics simulator, so you can develop robot programs without a hub on the desk:

$ pipx install 'openbricks[sim]'
$ openbricks sim run examples/full_robot.py --viewer

The sim runs the same script you’d push to the hub — a driver shim maps the openbricks API onto simulated motors and sensors, so ST3032Motor, DriveBase, color sensors, and distance sensors behave like their hardware counterparts.

Commands

$ openbricks sim preview [--world WORLD] [--x X] [--y Y] [--headless] [--duration S] [--seed N]

Loads the named world (an alias or a path to an MJCF file), splices in the default chassis, and opens the MuJoCo viewer so you can inspect the scene. --headless steps the physics for --duration seconds without opening a window — useful as a smoke test.

$ openbricks sim run SCRIPT [--world WORLD] [--x X] [--y Y] [--viewer] [--no-shim] [--seed N]

Loads the world plus the default chassis and executes SCRIPT against the simulated robot. --viewer opens the interactive MuJoCo window; without it the sim runs headless (CI-friendly). --seed makes randomized worlds reproducible.

Run openbricks sim --help for the full, always-current option list.

Notes

• The sim needs the [sim] extra (mujoco, numpy). Without it, openbricks sim … prints an install hint instead of crashing.

• Firmware-only users never need the simulator — it’s strictly host-side tooling.