dora-openarm

A Dora node that controls OpenArm.

Usage

Use this node from a dora-rs dataflow configuration. For a full configuration example, see enactic/dora-openarm-data-collection.

nodes:
  # ...
  - id: follower-right
    build: pip install dora-openarm
    path: dora-openarm
    args: "--side right --align-trigger gripper"
    inputs:
      # Only the event ID is used. The event value is ignored.
      request_position: leader/right_follower_position
      move_position: leader/right_follower_position
    outputs:
      - position
      - status

  - id: follower-left
    build: pip install dora-openarm
    path: dora-openarm
    args: "--side left --align-trigger gripper"
    inputs:
      # Only the event ID is used. The event value is ignored.
      request_position: leader/left_follower_position
      move_position: leader/left_follower_position
    outputs:
      - position
      - status
  # ...

Node arguments

Argument	Description
--side	OpenArm side to control. Default: right.
--config	Path to the OpenArm configuration file. Default: openarm_cell.yaml.
--can-interface	SocketCAN interface to use, overriding the one in the configuration file. Default: the configuration file's value.
--align-trigger	Optional trigger for the initial alignment step. Supported value: gripper.
--align-threshold	Alignment threshold in radians. Default: 0.1.
--align-delta-limit	Maximum joint delta per initial-alignment command in radians. Default: 0.001.
--[no-]align	Whether to align to incoming position commands after the arm starts. Default: enabled.
--[no-]stop	Whether to stop the arm when the node exits. Default: controlled by the STOP environment variable, or true when it is unset.
--[no-]refresh-every-request	Whether to refresh OpenArm state before each request. Default: controlled by the REFRESH environment variable, or true when it is unset.

Inputs

Input	Description
request_position	Requests the current arm position. The event ID is used and the event value is ignored.
request_state	Requests the current arm state. The event ID is used and the event value is ignored.
move_position	Sends a new target position to the arm. The value may be a struct containing qpos ([{"qpos": [...]}]), a position array directly, or a legacy struct containing new_position. When initial alignment is enabled, this input drives the alignment until it completes.

Outputs

Output	Description
position	Current arm position as a length-1 struct containing a float32 array: [{"qpos": [...]}].
state	Current arm state as a length-1 struct: [{"qpos": [...], "qvel": [...], "qtorque": [...], "tmos": [...], "trotor": [...], "motor_status": [...], "bus": {...}}]. qpos, qvel, and qtorque are float32 lists; tmos (MOS temperature) and trotor (rotor temperature) are int32 lists per motor, in °C. motor_status is a string list with one entry per motor in qpos order: the motor's own status name, or SILENT if it has stopped answering. bus is a struct describing the CAN interface: carrier (bool, whether the link is up) and the cumulative fault counters bus_off, error_passive, error_warning, ack_error, tx_overflow, rx_overflow, and net_down (int64). The counters only grow while the node runs, so compare against a baseline to see what happened during a given period.
status	Current control state as a string array: stopped, started, or aligned. With alignment enabled, aligned is emitted once initial alignment completes.

request_state publishes only state; request_position publishes only position. Each observation includes observation_timestamp: integer Unix wall-clock nanoseconds captured after the snapshot is read. Request metadata is preserved except for timestamp, which is removed so Dora supplies the output message timestamp.

Every output includes a process-local start_epoch, starting at zero and incrementing after each successful start, including --start-on-startup. Commands with an epoch must supply a non-boolean integer matching the current session; malformed or mismatched epochs are ignored. Commands without an epoch remain accepted for compatibility. The epoch resets on process restart and does not detect reordered commands within a session.

License

Licensed under the Apache License 2.0. See LICENSE for details.

Copyright 2026 Enactic, Inc.

Code of Conduct

All participation in the OpenArm project is governed by our Code of Conduct.