inspect-robots-widowx

Run Inspect Robots evals on existing WidowX 250S arms with OpenVLA or openpi policy servers.

Note

Trossen discontinued the WidowX 250S in July 2025. This package supports existing 250S rigs. The successor WidowX AI uses a different stack and is outside this package's scope.

Inspect Robots has two swappable inputs, a Policy and an Embodiment. This package provides three registered components:

• openvla policy: a REST client for OpenVLA's first-party /act server.
• openpi policy: a websocket client for community Bridge fine-tunes.
• widowx embodiment: a client for the BridgeData WidowX robot server.

Every pairing uses the same 7-D eef_delta_pose contract. Slots 0 through 5 are xyz and roll/pitch/yaw displacements. Slot 6 is an absolute normalized gripper target, where 0 is closed and 1 is open. Both policy pairings pass compatibility with zero errors and zero warnings.

Install

Client machine

Create an environment and install the package:

uv venv && source .venv/bin/activate
uv pip install inspect-robots-widowx
uv pip install "edgeml @ git+https://github.com/youliangtan/edgeml@b4b8495b489e7c973187742d2f2fe9aa016d9aca"
uv pip install "widowx_envs @ git+https://github.com/rail-berkeley/bridge_data_robot@b841131ecd512bafb303075bd8f8b677e0bf9f1f#subdirectory=widowx_envs"

Caution

The PyPI project named edgeml is an unrelated Microsoft package. Do not install it for this adapter. Use the pinned git command above.

Both BridgeData repositories are frozen and have seen no upstream development since 2024. The exact commits above make the old robot stack reproducible and limit dependency substitution risk. Review and vendor them for long-lived rigs.

Install openpi-client only when using an openpi policy server:

uv pip install "openpi-client @ git+https://github.com/Physical-Intelligence/openpi.git#subdirectory=packages/openpi-client"

Robot host

The robot host runs the upstream ROS1 Noetic BridgeData server inside its Docker environment. Pin the same server source used by the client install:

git clone https://github.com/rail-berkeley/bridge_data_robot.git
cd bridge_data_robot
git checkout b841131ecd512bafb303075bd8f8b677e0bf9f1f

Build and enter the ROS1 Noetic image using the scripts under the repository's widowx_envs/docker directory, then start the service inside the container:

widowx_env_service --server --port 5556

The ZMQ request and broadcast ports are 5556 and 5557 by default. Expose both ports to the client network. Install the upstream Interbotix udev rules on the host, pass the robot USB devices into the container, and verify stable device permissions after every replug. Run the upstream manual motion checks inside the container before connecting a learned policy.

GPU machine

Install OpenVLA from source and serve a Bridge checkpoint:

git clone https://github.com/openvla/openvla.git
cd openvla
pip install -e .
python vla-scripts/deploy.py \
  --openvla_path openvla/openvla-7b \
  --port 8000

The client sends unnorm_key="bridge_orig". Use a checkpoint that carries the Bridge normalization statistics or override unnorm_key for the fine-tune. OpenVLA's server does not resize requests. The default client transport resizes the raw 640x480 frame to 256x256 with Pillow Lanczos and performs an in-memory JPEG encode/decode round trip to approximate the Bridge evaluation pipeline.

Openpi has no official Bridge checkpoint. The openpi entry point is for a bring-your-own community or local Bridge fine-tune served by openpi.

Note

inspect-robots-franka also registers a policy named openpi (the DROID client). With both packages installed, --policy openpi resolves to whichever distribution the registry enumerates first; a mismatch fails loudly at preflight with an action dimension error. Uninstall one package or use the Python API to disambiguate.

Preflight

Preflight constructs metadata only. It does not connect to the robot or a policy server.

inspect-robots-widowx-preflight
inspect-robots-widowx-preflight --task cubepick-reach
inspect-robots-widowx-preflight --dry-run
inspect-robots-widowx-preflight --json --dry-run

A green report verifies the action dimension, control mode, rotation representation, gripper kind, frame, camera, state requirements, and optional scene realizability. JSON output includes a dry_run field.

Run on hardware

Add defaults to ~/.config/inspect-robots/config.ini:

[defaults]
policy = openvla
embodiment = widowx
scorer = success_at_end
max_steps = 200
store_frames = true

[policy.args]
server_url = http://192.168.1.20:8000
endpoint = /act
unnorm_key = bridge_orig

[embodiment.args]
host = 192.168.1.10
port = 5556
control_hz = 5.0
move_duration = 0.2
move_to_start = true

Run a task or direct instruction:

inspect-robots run --task cubepick-reach --policy openvla --embodiment widowx
inspect-robots "pick up the red block" --policy openvla --embodiment widowx

For openpi, change policy = openpi and set host, port, action_horizon = 10, and replan_interval = 5 under [policy.args].

Reset first calls the server's neutral reset. By default it then performs a blocking move to [0.3, -0.09, 0.26] using the reference OpenVLA 4x4 rotation. The attended flow asks for scene readiness after reset. Press Enter during the episode and answer y/N to score it. WidowXConfig(unattended=True) skips all prompts and operator polling.

Safety

Warning

Keep an operator at the e-stop for first runs, after container or udev changes, and whenever a checkpoint or camera arrangement changes.

• Hard clamp: every step() rejects non-finite actions and clips all seven values to delta_low/high inside the embodiment, independent of an Approver.
• Mixed delta and absolute semantics: xyz and rpy are per-step displacements, but the gripper slot is an absolute target. It is never a gripper rate.
• Control rate: the server uses move_duration=0.2 and the embodiment self-paces at 5 Hz. These fields must remain reciprocal.
• Workspace: the BridgeData workspace boundaries are enforced server-side. Client action bounds do not replace collision checking, physical stops, or workspace validation.
• Discontinued hardware: use this adapter only for maintained existing 250S rigs. Confirm spare parts, e-stop behavior, and container recovery before unattended operation.
• First-run verification: with the arm clear, use small asymmetric actions, confirm all xyz and rpy signs, then command gripper values 0.25 and 0.75 while the pose slots remain zero. Verify that the larger value opens the gripper.

In displacement mode, DeltaLimitApprover derives no additional default limit beyond the configured action box. There is no reference tracking. Clamping is applied to the action value itself. Do not use a scalar --max-action-delta 0.05 with this contract. A scalar intersects every slot with [-0.05, 0.05], so the absolute gripper's [0, 1] range becomes [0, 0.05]. That pins the gripper nearly shut forever. It does not rate-limit the gripper.

Python callers can provide a per-dimension vector and leave the gripper limit at 1.0:

import numpy as np
from inspect_robots import eval
from inspect_robots.approver import ChainApprover, ClampApprover, DeltaLimitApprover
from inspect_robots_widowx import OpenVLAPolicy, WidowXEmbodiment

embodiment = WidowXEmbodiment(host="192.168.1.10")
space = embodiment.info.action_space
approver = ChainApprover(
    ClampApprover(space),
    DeltaLimitApprover(
        space,
        max_delta=np.asarray([0.05, 0.05, 0.05, 0.25, 0.25, 0.25, 1.0]),
    ),
)
logs = eval(
    "cubepick-reach",
    OpenVLAPolicy(server_url="http://192.168.1.20:8000"),
    embodiment,
    approver=approver,
)

Configuration

Action and state units

Slot	Label	Action meaning	Observed state meaning
0	dx	x displacement in metres	x position in metres
1	dy	y displacement in metres	y position in metres
2	dz	z displacement in metres	z position in metres
3	droll	roll displacement in radians	controller-relative roll in radians
4	dpitch	pitch displacement in radians	controller-relative pitch in radians
5	dyaw	yaw displacement in radians	controller-relative yaw in radians
6	gripper	absolute normalized target	normalized opening, 0 closed and 1 open

The action declares rotation_repr="none" deliberately. The dimension labels carry the rpy meaning while inspect-robots issue #143 tracks support for Euler pose displacement guardrails. Declaring euler_xyz today makes the default delta approver reject the space.

WidowXConfig fields

Field	Default	Meaning
host	localhost	BridgeData robot server host
port	5556	ZMQ request port, with broadcast on port + 1
control_hz	5.0	Self-paced command rate
start_move_duration_s	0.8	Duration of the blocking move to the start pose at reset
move_duration	0.2	Server step duration, required to equal 1/control_hz
delta_low	translation -0.05, rotation -0.25, gripper 0	Per-step hard lower bounds
delta_high	translation 0.05, rotation 0.25, gripper 1	Per-step hard upper bounds
move_to_start	True	Apply the OpenVLA evaluation start pose after neutral reset
start_eef_pos	(0.3, -0.09, 0.26)	Translation inserted into the reference 4x4 transform
start_transform	None	Advanced 16-value row-major 4x4 override; replaces position and rotation
obs_timeout_s	10.0	Maximum wait for a non-None server observation
unattended	False	Skip readiness and scoring prompts
docs_extra	empty	Rig-specific notes appended to embodiment docs

There is no start_eef_quat field. The reference controller's start rotation cannot be reproduced from the commonly documented quaternion because the controller composes an internal default rotation.

OpenVLAConfig fields

Field	Default	Meaning
server_url	http://127.0.0.1:8000	OpenVLA server base URL
endpoint	/act	REST endpoint
unnorm_key	bridge_orig	Action normalization statistics key
timeout_s	30.0	HTTP request timeout
name	openvla	Policy label in eval logs
resize_px	256	Default transport square resize
jpeg_roundtrip	True	Match Bridge evaluation image compression

OpenVLA always advertises action horizon 1 and no replanning interval. A custom injected post_fn receives the raw camera frame and owns all preprocessing.

OpenpiConfig fields

Field	Default	Meaning
host, port	127.0.0.1, 8000	openpi websocket server
api_key	None	Optional authentication, excluded from eval policy config
action_horizon	10	Maximum returned action chunk length
replan_interval	5	Actions consumed before reinference
name	openpi	Policy label in eval logs
resize_px	224	Default resize-with-pad size

Development

Use the local cache path required by this workspace:

export UV_CACHE_DIR="$PWD/.uv-cache"
uv sync --extra dev
uv run ruff check .
uv run ruff format --check .
uv run mypy
uv run pytest --cov

The tests inject clients, transports, clocks, sleeps, operator I/O, and end polling. They require no robot, server, camera, network, or stdin. Coverage is enforced at 100 percent with branch coverage enabled.

Dependency changes require uv lock. CI uses uv sync --locked; the weekly canary resolves current allowed versions without the lockfile.

Citation

@software{inspect-robots-widowx,
  author  = {Robocurve},
  title   = {Inspect Robots WidowX: OpenVLA and openpi adapters for WidowX 250S arms},
  year    = {2026},
  url     = {https://github.com/robocurve/inspect-robots-widowx},
  license = {MIT}
}

See CITATION.cff for citation metadata.

License

MIT