blacknode-robot

Blackndoerobotvisiondemo2-github.mp4

Generic robot setup nodes for Blacknode.

Install this Blacknode extension package to add robot hardware setup to the visual workflow editor: find USB serial robot devices, fix Linux serial permissions, launch and stop a driver process, and emit reusable robot profiles for downstream control nodes — drivable from workflows or AI agents over MCP.

This package owns the user-facing robot abstraction:

• find USB serial robot devices
• explain Linux serial permissions
• describe how a robot driver should start
• start/stop a driver process
• build, save, duplicate, load, and calibrate reusable robot profiles

Robot-specific packages provide protocol driver descriptors and hardware bridges. Transport packages such as blacknode-ros2 verify and control the standard interface exposed by the driver.

Nodes

Coding agents should read AGENTS.md before changing this package. It defines the package boundary, calibration identity contract, motion safety, and verification commands.

Node	What it does
RobotDriverDescriptor	Declares a driver command template and standard topics
Robot	Selects a robot, automatically finds its connection, applies calibration, and optionally starts its driver
RobotJointDefinition	Defines one named joint, servo ID, range, zero, and direction
RobotJointList	Combines any number of joint definitions; another socket appears as the list fills
RobotDefinition	Builds a reusable robot profile and driver contract visually
RobotProfileSave	Saves a profile under robots/<profile_id>/profile.json
RobotProfileLoad	Loads a profile and the calibration for a connected hardware ID
RobotProfileList	Lists built-in and locally saved profiles
RobotProfileDuplicate	Copies a built-in or local profile under a new editable name
RobotCalibrationRecorder	Safely records released-arm limits and a home pose for one physical robot
RobotDriverLauncher	Starts/stops a driver process from the descriptor
RobotConnectionDashboard	Shows USB, driver, ROS interface, live joint positions, home references, safe ranges, and calibration source in one view

Changing the generic Robot.profile_id invalidates the old dashboard. Press Run to apply it: if its generated driver command differs, Blacknode safely stops the prior managed process before starting the selected profile. A PROFILE DEFAULTS dashboard has no saved calibration for that profile and hardware ID.

For one robot, use only Robot; it automatically discovers available hardware and uses selection: 0. Duplicate it and choose selection: 1 for a second robot. If the discovered order is reversed, swap those two indexes. Camera and future sensor facades use the same selection convention. The selected entry's serial number (or port path when no serial is available) becomes the robot's hardware_id; discovery's index-0 shortcut values never override a different selected entry.

The Properties panel keeps transport controls under Advanced. They are not required for normal setup: probe_open actively opens candidate serial ports for diagnostics, vendor/product IDs narrow discovery to a USB adapter model, and hardware_filter pins a node to one stable adapter identity. Stable identity is recommended after calibration or for unattended motion so two identical robots cannot silently exchange roles. Hidden compatibility nodes still provide low-level diagnostics for old workflows, but USB is an implementation of a robot connection rather than the public abstraction.

The SO-ARM101 Leader Follower template uses robot indexes 0 and 1, separate driver run IDs, and /leader and /follower ROS topic prefixes. It releases only the leader, starts the follower controller in disarmed preview, and requires saved calibration for both physical devices. For a permanent installation, promote hardware_filter from Advanced and bind each role to its adapter serial. Its default configuration uses tracking_mode=direct at 60 Hz with no deadband or relative step limiter. The Feetech driver batches all joint reads and all goal writes into synchronized bus transactions, while calibration limits, stale-stream suppression, and explicit arming still apply.

Contract

The generic pipeline is:

Robot -> discovered connection + calibrated profile + managed driver

Driver descriptors use {serial_port} as the placeholder for the discovered USB path:

python scripts/my_robot_driver.py --port {serial_port}

The resulting robot profile carries:

• state_topic
• command_topic
• optional config_topic
• usb
• driver
• interface

Robot-specific packages should fill in the descriptor. Transport packages should verify and use the interface.

Robot Selection and Drivers

Use the generic Robot node in new workflows. Its dropdown includes built-in and locally saved profiles; it discovers the selected connection, applies the matching calibration, and checks, starts, or stops the driver itself. The old discovery and profile-loader types remain hidden for workflow compatibility.

RobotDefinition.driver_script is also a dropdown populated from installed drivers/*_driver.py files when Blacknode starts. Adding a driver file and restarting Blacknode makes it selectable without changing the node. A custom executable or non-Python launch path can still use protocol=custom with an explicit command_template.

The curated SO-ARM101 preset uses the same profile schema as a visual custom robot. Supporting another arm on the bundled Feetech protocol normally means assembling joint nodes and saving a profile; it does not require changing Python. Only a genuinely new wire protocol needs another bus driver.

Custom Robot Profiles

Open Editable SO-ARM101 Profile as a working example. Each RobotJointDefinition names a stable joint and sets its servo ID, provisional range, center tick, and direction. RobotJointList preserves their order; RobotDefinition creates the profile; and RobotProfileSave makes it reusable.

To reuse the same mechanical definition under another identity, use RobotProfileDuplicate with source_profile_id=so_arm101 and choose a new ID. For structural changes, copy the Editable SO-ARM101 Profile workflow and edit its visible joint nodes before saving. Profile and joint IDs normalize to lowercase snake_case, limited to 64 characters, and must be unique. Display names are free-form and can change without breaking workflows.

Connect Robot.hardware to RobotDefinition.hardware. The definition copies the real USB vendor ID and product ID reported internally; these four-digit values identify the hardware manufacturer/product and are not random robot IDs. Manual vendor_id and product_id values remain advanced overrides. The adapter serial—or its device path when no serial exists—selects the calibration for one physical assembly.

Local robot data is deliberately separate from the package source:

robots/
  my_robot/
    profile.json
    calibrations/
      usb_serial_or_device_id.json

Set BLACKNODE_ROBOTS_DIR to move this library elsewhere. The default robots/ directory is ignored by Git because calibrations describe a specific physical assembly. Copy or version it deliberately when sharing a machine configuration.

Guided Calibration

Open Robot Guided Calibration after saving a profile:

1. Load the profile and start discovery with the robot connected.
2. Press Release + live pose on Manual Move and physically support the arm.
3. Confirm live joint values are changing, then press Start recording.
4. Slowly move every joint through the safe physical range you intend to use. Do not force a hard stop.
5. Put the robot in the pose that should read as zero and press Capture Home.
6. Press Stop recording whenever you want to pause extrema collection without losing samples. Current pose remains live; press Resume recording to continue.
7. Press Save calibration. The recorder applies the configured safety margin inside the observed extrema and saves it under the hardware ID.
8. Press Hold position only while the arm is supported and the workspace is clear.

Recording never commands movement. It refuses to start while torque is on, and it will not save until every configured joint has been observed and a home pose has been captured. Its CURRENT pose, observed ranges, sample count, dashboard, report, and connected Output nodes update through the live runtime. Robot automatically applies the matching device calibration when given the discovery hardware output; another physical robot with the same profile keeps a separate calibration.

While recording, the most strongly moving joint is labeled CAPTURING. Its row turns blue, and a newly extended limit flashes amber with MIN ↓, MAX ↑, or RANGE. This distinguishes ordinary motion inside an already observed range from a sample that actually changed the saved extrema.

SO-ARM101 (preset: so_arm101)

Drives a real SO-ARM101 — 6x Feetech STS3215 serial-bus servos (shoulder_pan, shoulder_lift, elbow_flex, wrist_flex, wrist_roll, gripper; servo IDs 1-6; 1 Mbps) — through drivers/feetech_bus_driver.py. The preset defaults to transport=auto: it uses native rclpy when available and otherwise uses rosbridge. The transport can still be forced for advanced deployments. In rosbridge mode the serial connection remains local to the driver machine.

pip install -r packages/blacknode-robot/requirements.txt   # servo SDK + roslibpy

1. Plug in the arm, then run Robot with action=check to confirm its connection is found and accessible. This confirms the adapter is enumerated, not that robot power or servo communication is healthy; use the driver connection state for that.
2. Load the SO-ARM101 Motion Test template (templates/so-arm101-motion-test.json): Robot (so_arm101, starts the driver) → ROS2Status → ROS2JointState → ROS2SetJoint (armed=false by default) → ROS2MotionDashboard.
3. Press Run. With armed=false this only proves the pipeline: the driver starts, ROS2Status selects native ROS 2 or rosbridge, and ROS2JointState shows the arm's live pose. The arm must not move or twitch during this step — see Safety below for why.
4. Set a joint name and armed=true on ROS2SetJoint, recook. It syncs to the current pose, ramps to the target, and the dashboard shows before/after.

Manual Move + Live Pose

The motion-test template includes ROS2ManualMove between connection status and motion. Its safe default is Monitor only, which changes no torque state and starts an explicitly labeled live pose monitor.

• Press Release + live pose to disable servo torque while the driver keeps publishing joint positions. Support the arm before pressing it; it may go limp.
• Move the supported arm by hand. The Teach node's unconnected dashboard output refreshes from the runtime monitor and shows the latest pose.
• Press Hold position to hold again. The driver reads every servo and writes those exact positions as goals before enabling torque. Motion is blocked during the transition. The selected button and dashboard report the actual current mode rather than only the last requested action.
• Stop all remains the emergency-safe shutdown: it stops the driver and disables torque, so live state publishing also stops.

Safety

• Torque-enable sequencing. Feetech STS servos snap toward whatever is already sitting in Goal_Position the instant Torque_Enable switches on — that register is not guaranteed to already equal the physical position. feetech_bus_driver.py always reads every servo's current position first, writes that same value back as Goal_Position while torque is still off, and only then enables torque — so there is nothing for the servo to snap toward. If the arm moves or twitches the moment the driver starts, stop and investigate before arming anything.
• Shutdown behavior. By default the driver disables torque on every servo when it stops (clean shutdown, crash, or RobotDriverLauncher action=stop) — the arm goes limp rather than holding its last position indefinitely with no watchdog. Override with --no-torque-off-on-exit in the preset's command_template (or a custom RobotDriverDescriptor) only if holding position is actually the safer failure mode for your specific mounting.
• Rosbridge reconnects without restarting the hardware driver. A dropped WebSocket no longer leaves an alive-but-silent process. The driver keeps the serial session open, waits for roslibpy to reconnect, then republishes its safety configuration and current joint pose before resuming state updates. Command writes and state reads share one bus lock so Feetech packet transactions cannot overlap. Confirmed command writes consume each servo's status response, and malformed short read packets retain the last valid pose instead of terminating the driver. Late driver exits retain their error text in runtime status instead of disappearing as a generic offline process.
• The editor's "Stop all" reaches the driver process too. robot.py exposes runtime_status()/stop_runtime_services() (registered in the main Blacknode editor's _RUNTIME_MODULES), so pressing "Stop all" sends SIGTERM to every driver this session launched — which is what actually triggers the torque-off-on-exit shutdown above. Before this was wired in, "Stop all" only stopped camera/tracking/reasoning stream helpers and left the robot driver (and torque) running silently in the background.
• Joint limits are placeholders until calibrated. The min_deg/max_deg values in the SO-ARM101 base profile are not a verified safe envelope for your assembly. Use Robot Guided Calibration with torque released to record intended physical ranges and a safety margin before commanding broad motion. Never discover limits by driving an armed joint into its hard stop.
• Calibration details. feetech_bus_driver.py initially assumes each servo's raw center tick (2048 of 4095) is that joint's mechanical zero and that none of the joints are mirror-mounted. Saved profiles carry direction and center information, while device calibrations supply measured home ticks and safe ranges automatically. The --home-ticks and --invert CLI flags remain available as advanced driver-level overrides.
• Verify the control-table addresses before ever writing. Run python packages/blacknode-robot/drivers/feetech_bus_driver.py --dry-run --port <serial_port> --joints "<name:id:min:max,...>" first: it only reads Present_Position for every servo ID and prints the result — it never touches Goal_Position or Torque_Enable. Confirm every servo responds with a plausible tick (0-4095) before trusting the driver with real writes.

Keep a physical power cutoff within reach and clear the workspace before arming.

License

Apache-2.0, same as Blacknode.