inspect-robots-yam 0.4.0

Inspect Robots adapters for I2RT YAM bimanual arms driven by MolmoAct2.

inspect-robots-yam

Run Inspect Robots evals on real I2RT YAM bimanual arms driven by MolmoAct2.

Note: This project is in early development. The API may change between releases, so pin a version before depending on it.

Inspect Robots has two swappable inputs: a Policy (the VLA brain) and an Embodiment (the robot body + world). This package provides both for the YAM + MolmoAct2 stack, so any embodiment-agnostic Inspect Robots task (e.g. all of KitchenBench) runs on real arms:

• molmoact2 policy: a thin client for MolmoAct2's first-party bimanual-YAM /act server (the model owns the GPU + weights in its own process).
• yam_arms embodiment: the I2RT joint-position driver, with a hard safety clamp, operator-in-the-loop success, and self-paced control.

Both declare the same 14-D joint-position contract (2 arms × [6 joints + gripper], cameras top/left/right, packed joint_pos state), so Inspect Robots's compatibility check passes with zero errors and zero warnings. This is verifiable before any motion.

inspect-robots run --task kitchenbench/pour_pasta --policy molmoact2 --embodiment yam_arms

Note: the CLI forwards scalar key=value knobs only. It cannot inject a camera_reader, which hardware runs require. Launch from Python (see Run on hardware) or register your own entry-point factory that bundles the cameras; otherwise yam_arms fails fast with a ConfigError at reset(), before any driver connect or motion.

Install (on the robot/GPU machine)

uv pip install "inspect-robots-yam[client]"
# The i2rt driver is GitHub-only (not on PyPI), so the [yam] hardware extra
# can't resolve from PyPI — install the driver directly instead:
uv pip install "i2rt @ git+https://github.com/i2rt-robotics/i2rt"

• client → requests + json-numpy (the /act transport).
• i2rt → the I2RT YAM arm driver, required for real hardware (the [yam] extra declares it, but only resolves in a git/dev install where [tool.uv.sources] applies: from PyPI, install it directly as above).

Then download the model weights (needs a Hugging Face token) and start the server, from the MolmoAct2 repo:

huggingface-cli download allenai/MolmoAct2-BimanualYAM
python examples/yam/host_server_yam.py          # serves /act on :8202

Preflight: prove compatibility before any motion

inspect-robots-yam-preflight                                  # dims/semantics/cameras/state
inspect-robots-yam-preflight --task kitchenbench/pour_pasta   # + scene realizability
inspect-robots-yam-preflight --dry-run                        # affirm no motion

A green preflight means action dim (14), control mode (joint_pos), cameras, and state keys all line up. It does not prove the joint values are interpreted the same way. See Safety below.

Run on hardware

You must provide a camera_reader (there is no universal camera API) returning {"top_cam", "left_cam", "right_cam": HxWx3 uint8}. From Python:

from inspect_robots import eval
from inspect_robots.approver import ClampApprover
from inspect_robots_yam import MolmoAct2Policy, YAMEmbodiment, YamConfig

emb = YAMEmbodiment(YamConfig(left_channel="can0", right_channel="can1"),
                    camera_reader=my_camera_reader)
pol = MolmoAct2Policy(server_url="http://127.0.0.1:8202")

(log,) = eval("kitchenbench/pour_pasta", pol, emb,
              approver=ClampApprover(emb.info.action_space))  # defense in depth
print(log.status, log.results.metrics)

At each episode end the embodiment asks the operator (y/N); a yes records termination_reason="success", which KitchenBench's task_success scorer reads. The operator prompts need an interactive terminal: a dead stdin raises EmbodimentFault (the framework's always-halt path). For runs with no operator, set YamConfig(unattended=True) (CLI: -E unattended=true): all operator prompts are skipped and every episode runs to max_steps, scoring as a failure.

Safety

• Hard clamp backstop. Every command is clipped to YamConfig.joint_low/high inside step(), independent of any Inspect Robots Approver: unclamped model outputs can never reach the motors. Set the arm slots to your real YAM joint limits (the defaults are conservative placeholders: joints ±π, gripper 0–1). But note the limits are in policy units per the table below: gripper slots 6 and 13 stay normalized 0–1, only slots 0–5 and 7–12 are radians.
• Use ClampApprover on hardware for a second layer.
• Zero-gravity handoff jump. The arms connect in zero-gravity mode by default (YamConfig(zero_gravity_mode=True), passed through to the i2rt driver), so the first stiff PD command (homing or the first action) can jump from wherever the arm was idling. Nothing bounds the per-step joint delta yet (tracked as a known issue); stand clear at reset() and prefer a home_pose near the resting pose.
• Absolute vs. delta joints: verify first. MolmoAct2's YAM actions are treated as absolute joint targets by default. If your checkpoint emits deltas, set YamConfig(joints_are_delta=True) (the embodiment converts to absolute internally so the declared joint_pos stays honest). Inspect Robots's compat check cannot tell these apart: confirm with --dry-run and a single slow jog before running a task.
• Gripper polarity/trim. The i2rt driver already exposes the YAM gripper as normalized 0–1 in both directions, so the defaults (gripper_open=0.0, gripper_closed=1.0) are an identity map and correct for standard grippers. YamConfig(gripper_open=..., gripper_closed=...) is a polarity/trim remap over that already-normalized range. Its main use is a gripper wired with inverted polarity (gripper_open=1.0, gripper_closed=0.0). The remap is a bijection: commands are de-normalized on the way out and observations are re-normalized on the way back, so the model always sees 0–1. Warning: values outside [0, 1] are forwarded on a path i2rt does not clip. Avoid them unless you have verified your firmware's behavior.

Configuration

Units: every 14-D vector uses the same layout

joint_low/joint_high, home_pose, actions, and the observed joint_pos state all use policy units:

Slots	Meaning	Unit
0–5, 7–12	left / right arm revolute joints	radians
6, 13	left / right gripper	normalized 0–1 (0 = open, 1 = closed)

Hardware gripper units (via gripper_open/gripper_closed) exist only at the driver boundary; nothing you configure here is in hardware gripper units.

YamConfig: left_channel, right_channel, gripper_type (i2rt GripperType enum name, e.g. LINEAR_4310; grippers only: NO_GRIPPER/YAM_TEACHING_HANDLE would break the 14-D packing and are rejected), control_hz, cam_height/width, joint_low/high, home_pose, gripper_open/closed, joints_are_delta, zero_gravity_mode (default True; see Safety), unattended (default False; skip operator prompts). MolmoActConfig: server_url, endpoint, num_steps, timeout_s, camera_order, state_key, cam_height/width.

Scalar knobs are settable from the CLI: inspect-robots run -P server_url=http://gpu:8202 -E left_channel=can0 ....

Development

Dependency changes: after editing dependencies in pyproject.toml, run uv lock and commit the updated lockfile. CI installs with uv sync --locked and fails with "the lockfile needs to be updated" if you forget. Day-to-day conventions (PR-only main, the required ci-ok check, one-click releases) are documented in CLAUDE.md.

uv venv && uv pip install -e ".[dev]"     # inspect_robots + kitchenbench from PyPI
uv run pre-commit install
uv run pytest --cov                        # 100% coverage required
uv run ruff check . && uv run mypy

The whole suite runs with no hardware, no server, and no stdin: the i2rt driver, cameras, the /act transport, the clock, and operator I/O are all injected. The default hardware seams are excluded from coverage (# pragma: no cover).

Citation

If you use Inspect Robots YAM in your research, please cite it:

@software{inspect-robots-yam,
  author  = {Robocurve},
  title   = {Inspect Robots YAM: Adapters for I2RT YAM bimanual arms},
  year    = {2026},
  url     = {https://github.com/robocurve/inspect-robots-yam},
  version = {0.3.0},
  license = {MIT}
}

License

MIT