OpenArm ROS 2 Guide

OpenArm ROS 2 Guide (v1.0 bimanual, Jazzy, main branch)

Current version: V3

Earlier versions are kept unchanged in the version archive.

What changed in V3 (2026-10-09)

• New: Part III (§30–§43), a complete, beginner-level guide to running a trained policy with lerobot-rollout: concepts, checking the model files, every flag, what happens when, a first run in small steps, tuning, evaluation, DAgger, troubleshooting. It replaces the old §24.4–§24.11, which were short. §24.5 “Which policy” is now §24.4.
• Correction: lerobot-rollout refuses recording datasets whose name doesn’t start with rollout_. The V2.2 examples (eval_…, hil_…) would have failed at start-up. Fixed in §37 and §38.
• Correction: lerobot-record appends a date-time tag to the dataset name unless --dataset.no_stamp=true, so the V2.2 training command couldn’t find the dataset under the name it was recorded with. §24.1 now uses no_stamp.
• New pitfall: zeus logs in to a Wayland session, where the LeRobot keyboard controls (episodic, DAgger) probably don’t work (§37.3).

What changed in V2.2 (2026-10-09)

• Correction: V2.1 said that with interpolation_method: none the trajectory controller “ramps linearly” to the first point over time_from_start. That was wrong. It holds the current position for the whole time_from_start and then jumps to the target (confirmed in sim, see log 2026-10-09). On real motors that’s a full-speed step. Fixed in §4, §8.1, §12.3 and §16.
• New: how to switch the bringup controllers to interpolation_method: splines, and how to check it (§4). This is now a pre-flight item for the real robot (§12.1).
• Correction: the §12.1 checklist said can0 = right arm. On zeus it’s the reverse (left = can0, §22).

A practical reference for the OpenArm ROS 2 stack as installed in the openarm container on zeus: how it is built, how to run it in simulation, how to command it, and how to bring up and command the physical OpenArm v1.0 over SocketCAN. Part II covers teleoperation, data collection and policy learning with Hugging Face LeRobot, installed on the host, and how it relates to the ROS 2 stack. Part III is a step-by-step guide to running a trained policy on the robot with LeRobot, written for someone doing it for the first time.

Versions this guide was written against (inside the container, /root/ros2_ws/src):

Repo	Commit	Date
enactic/openarm_ros2 (main)	b9d7a67	2026-10-06
enactic/openarm_description	c103041	2026-10-02
enactic/openarm_can	f340d4b (v1.4.0)	2026-09-16
huggingface/lerobot (main, host, conda env lerobot)	b863b42 (v0.6.2)	2026-10-08

ROS 2 Jazzy, ros2_control 4.x, MoveIt 2. Everything below was checked against these sources. Where behaviour could not be verified without hardware, it is marked ⚠ verify.

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