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: cameras are configured with three plain device paths (top/left/right_cam_device), so the whole rig is drivable from config.ini or -E key=value flags with no custom code. A Python camera_reader remains available for exotic camera stacks. With neither configured, yam_arms fails fast with a ConfigError at reset(), before any driver connect or motion.

Install (on the robot/GPU machine)

uv venv && source .venv/bin/activate
uv pip install inspect-robots-yam
# The i2rt driver is git-only and not on PyPI. Install it directly.
# The build-constraints file works around a build failure in i2rt's ruckig
# dependency (source-only releases that no longer build under scikit-build-core
# 1.0; the pin below 0.10 matches i2rt's own in-repo workaround):
echo 'scikit-build-core<0.10' > build-constraints.txt
uv pip install --build-constraints build-constraints.txt "i2rt @ git+https://github.com/i2rt-robotics/i2rt"

The base package includes the /act transport and builtin OpenCV camera reader. Only i2rt, the I2RT YAM arm driver required for real hardware, needs the separate git install. The scikit-build-core build constraint can be dropped once ruckig ships a release with the fix from pantor/ruckig#261 and i2rt moves off ruckig==0.15.3. The camera reader depends on opencv-python-headless; if your environment also carries opencv-python, the two share the cv2 module and the last one installed wins.

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

Check dims, semantics, cameras, and state keys:

inspect-robots-yam-preflight

Also check a specific task's scenes are realizable:

inspect-robots-yam-preflight --task kitchenbench/pour_pasta

Affirm that no motion will occur:

inspect-robots-yam-preflight --dry-run

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

Write your defaults once. The interactive wizard interviews this plugin's declared devices (three cameras and both arms' CAN channels) with live probes, including unplug-to-identify:

inspect-robots setup

Or write the file yourself, replacing the three camera paths with your rig's V4L2 color nodes (use stable /dev/v4l/by-id/... or udev-symlink paths; bare /dev/videoN numbers reshuffle on every replug):

mkdir -p ~/.config/inspect-robots && cat > ~/.config/inspect-robots/config.ini <<'EOF'
[defaults]
policy = molmoact2
embodiment = yam_arms
scorer = success_at_end    # scores the operator's y/N answer at episode end
max_steps = 1200           # 120 s at 10 Hz
rerun = true               # live viewer of cams/state/actions (inspect-robots[rerun])
store_frames = true        # keep the policy's camera frames per run

[embodiment.args]
top_cam_device = /dev/v4l/by-id/YOUR-TOP-CAM
left_cam_device = /dev/v4l/by-id/YOUR-LEFT-CAM
right_cam_device = /dev/v4l/by-id/YOUR-RIGHT-CAM
EOF

Then tell the robot what to do:

inspect-robots "place the fork on the plate"

The attended flow: position the scene, press Enter to start, press any key to end the episode, answer y/N to score. The status line counts up against the run's real step limit (t = 42s / 120s) with no configuration needed (requires inspect-robots newer than 0.8.1; on older cores set max_steps_hint).

For exotic camera stacks (or full programmatic control), the Python API takes a custom camera_reader returning {"top_cam", "left_cam", "right_cam": HxWx3 uint8}:

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.

Drive the arms with an LLM (agent mode)

With the inspect-robots-agent plugin installed, a frontier LLM can drive the arms directly: it sees the cameras and the labeled 14-D state, and moves joints by name (left_j0..left_gripper, right_j0..right_gripper) through smooth, approver-checked motions.

Copy the env template and add your API key:

cp .env.example .env

Install the add-on:

uv pip install inspect-robots-agent inspect-robots-yam
inspect-robots config set embodiment yam_arms     # once, per machine

Cameras come from the builtin reader: set the three *_cam_device paths in ~/.config/inspect-robots/config.ini (see Quickstart above) or pass them as -E flags per run. Then run the LLM on the robot:

inspect-robots "place the fork on the plate" --policy agent \
    -P model=anthropic/claude-fable-5

Note: Invoke the CLI as plain inspect-robots, not uv run inspect-robots. Inside a uv project, uv run first re-syncs the environment to the project's lockfile, which uninstalls add-ons that are not declared dependencies (the run above then fails with no policy named 'agent'). To use uv run anyway, pass --no-sync or make the add-on a real dependency with uv add inspect-robots-agent.

Safety guardrails (a bounds clamp plus a per-step delta limit derived from the declared action space) are wired in by default for every CLI run; turning them off requires an explicit --disable-guardrails.

Warning: Before any unattended agent run, verify on your rig that the arms hold position while the LLM thinks (seconds between action chunks). Run the bundled check per arm and per mode, arms mid-workspace, e-stop in hand:

inspect-robots-yam-holdcheck can_left --zero-gravity true
inspect-robots-yam-holdcheck can_right --zero-gravity true

(Channel names match your rig's CAN interfaces; can0/can1 on default setups.) PASS in the mode you run agents in closes the verification. The default zero_gravity_mode=true puts the i2rt driver in a gravity-compensated, compliant mode; if it drifts but --zero-gravity false holds, run agents with -E zero_gravity_mode=false. If both drift, file an issue with the numbers. Keep a hand on the e-stop for the first runs.

YAM ships with a factory resting pose at encoder zero for every joint and 0.0 (the closed end of the stroke) for both grippers, so standard upright rigs end with a gentle 3-second park instead of going limp mid-air. Override it per rig when needed. Pose fields accept comma-separated values from the CLI and config.ini:

[embodiment.args]
rest_pose = -0.002,0.002,0.002,-0.089,0.007,-0.026,0.0,-0.006,0.002,0.001,-0.087,-0.007,-0.019,0.0

Set rest_pose = none to opt out of the factory target and park at the pose captured before the first commanded motion instead.

In delta mode (-E joints_are_delta=true) the declared action space is the per-step displacement box (YamConfig.step_limits, default 0.2 rad per joint and a full gripper stroke per step); the absolute joint limits still clamp the summed command inside the embodiment as a backstop. A delta-configured rig must be paired with a delta-declaring policy (-P joints_are_delta=true for molmoact2); a mismatch fails the compatibility check before any motion.

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). Homing and rest-pose motions ramp at control_hz, but the first policy action is still a stiff PD command that can jump from wherever the arm ended up. Nothing bounds the per-step joint delta yet (tracked as a known issue); stand clear when the episode starts, and set home_pose so episodes begin from your checkpoint's trained start state.

• Park pose must rest under gravity. On close, the arms ramp back to an explicit per-rig rest_pose or the factory all-zero target, and torque is released once the ramp finishes. Set rest_pose=none to opt out and fall back to the pose captured at the first reset. Verify that the factory target is a supported resting pose on your rig, or start runs (or set rest_pose) with the arms in one, not held mid-air: whatever pose the park ends in is the pose the arms go limp from. The park path is not collision-checked, so keep the workspace clear at episode end. The default parks with both grippers closed (wire 0), so anything still held stays gripped at park: clear the grippers before ending the run, or park open with a per-rig rest_pose whose gripper slots are 1.0. Override rest_pose on rigs whose joint limits exclude zero, since the park target is clamped through the same per-joint box as every command.

• 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 wire convention is normalized 0–1, with 1 open and 0 closed. The defaults (gripper_open=1.0, gripper_closed=0.0) preserve an identity map for the standard i2rt driver. These fields are the measured driver-native positions at the open and closed ends of the stroke. Configure an inverted or offset gripper with its actual endpoints, for example gripper_open=0.72, gripper_closed=0.04. Commands are de-normalized on the way out and observations are re-normalized on the way back, so the model always sees the wire convention. Warning: values outside [0, 1] are forwarded on a path i2rt does not clip. Avoid them unless you have verified your firmware's behavior.

  Compatibility (pre-1.0): earlier releases interpreted these fields with the opposite endpoint mapping. A config that explicitly copied the old defaults (gripper_open=0.0, gripper_closed=1.0) now inverts its gripper. A config that followed the old inversion recipe (gripper_open=1.0, gripper_closed=0.0) no longer inverts because those values are now the identity defaults. On identity-calibrated rigs, home_pose, rest_pose, and custom joint_low/joint_high retain their numeric behavior, but their gripper-slot meaning is now 1 open and 0 closed.

Configuration

Units: every 14-D vector uses the same layout

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

Hardware gripper units (via gripper_open/gripper_closed) exist only at the driver boundary; pose and limit vectors never use driver-native 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 (reset ramps here smoothly over rest_secs rather than jumping), rest_pose (close park target; defaults to the factory all-zero pose, accepts a per-rig override, and accepts none to fall back to the pose captured at the first reset before torque is released), rest_secs (ramp duration, default 3.0), gripper_open/closed, joints_are_delta, zero_gravity_mode (default True; see Safety), unattended (default False; skip operator prompts), top/left/right_cam_device (V4L2 paths for the builtin camera reader; all three or none), max_steps_hint (deprecated: on inspect-robots newer than 0.8.1, framework runs feed the status line the real horizon automatically; the hint is only a fallback for direct rollout() calls or older cores; bounds nothing). The current factory value is available for inspection as inspect_robots_yam.config.DEFAULT_REST_POSE; this is an informational constant, not a stable import. MolmoActConfig: server_url, endpoint, num_steps (the wire field: the server's flow-matching denoising steps, not the chunk length), action_horizon (the checkpoint's advertised chunk length, 30 for the bimanual YAM tag; metadata only), 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

Every public module, class, and function needs a docstring, enforced by Ruff D1; state the contract instead of restating the symbol name.

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