SO-101 follower arm bring-up: joint states + safe joint control#50
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SO-101 follower arm bring-up: joint states + safe joint control#50MJohnson459 wants to merge 1 commit into
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Bring the mounted SO-101 follower arm under software control: live joint states, safe soft-limited joint commands, a jog CLI, and bench tools. There is no leader arm and none is assumed anywhere. Stack decision (documented in mote_arm/README.md): direct Feetech control, not LeRobot. The arm servos are the same STS-class Feetech bus as the drive wheels, so this reuses the servo approach rather than pulling torch onto the lean Pi env (which the repo keeps torch off, isolating inference off-board). The only new dep is the pure-Python feetech-servo-sdk (scservo_sdk). New mote_arm package (Python/ament): - config.py: parses robot.yaml `arm:`; encoder<->rad conversion + soft-limit clamping. ROS-free and unit-tested (15 tests) so the safety maths is verified without hardware. - bus.py: FeetechBus, a thin scservo_sdk wrapper (lazy import so build/lint/test stay hardware-free); register map matches mote_hardware. - arm_driver (node, `pixi run arm`): single bus owner. Publishes /joint_states for the arm, accepts soft-clamped goals on arm/goal, exposes arm/set_torque. Starts LIMP and goes limp on shutdown — nothing moves without an explicit command. - jog (CLI, `pixi run arm-jog`): interactive per-joint jog; a client of the driver (no bus contention), clamped both sides, torque-off on exit. - arm_check (`pixi run arm-check`): standalone enumeration/health + a ready-to-paste udev line + --save-home calibration snapshot. Supporting changes: - robot.yaml: `arm:` section (port, baud, IDs, per-joint soft limits, home, invert) — the single source of truth; limits are conservative placeholders to calibrate at the bench. - mote.urdf.xacro: arm links/joints behind arm:=true (sim passes arm:=false) so robot_state_publisher animates the arm in TF from /joint_states. - 99-mote.rules: commented /dev/mote_arm rule (pin by serial; arm_check prints the line). - pixi.toml: feetech-servo-sdk dep; arm / arm-jog / arm-check tasks; mote_arm added to the test set. Torque policy and calibration in mote_arm/README.md; human bench runbook in mote_arm/BENCH.md. GitHub #2 (camera doesn't fit with the arm) noted as an unresolved mechanical clash, not addressed here. Verified: pixi run build, pixi run test (104 passed incl. 15 mote_arm), pixi run lint all green; xacro generates with the arm on (real) and off (sim). Co-Authored-By: Claude Opus 4.8 <[email protected]> Claude-Session: https://claude.ai/code/session_01TQqUVutHYLPLToYtiP8BSj
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SO-101 follower arm bring-up: joint states + safe jog control.
Branch worktree-arm-so101-bringup, committed (not pushed). No leader arm assumed anywhere.
STACK DECISION (documented in mote_arm/README.md): direct Feetech control, NOT LeRobot. The arm servos are the same STS-class Feetech bus as the drive wheels, so this reuses the existing servo stack instead of pulling torch onto the deliberately-lean Pi env (the repo isolates all torch to off-board inference envs). Sole new dep: pure-Python feetech-servo-sdk (scservo_sdk) — the same SDK LeRobot uses, so a LeRobot path stays open. Episode-recording path = ROS rosbags (already used for map provenance).
WHAT LANDED — new mote_arm Python/ament package:
Supporting: robot.yaml arm: section (single source of truth; port/baud/IDs/soft-limits/home/invert), URDF arm links behind arm:=true (sim passes arm:=false), commented /dev/mote_arm udev rule, pixi tasks + feetech-servo-sdk dep + mote_arm in the test set. CLAUDE.md package docs updated.
VERIFIED: pixi run build, pixi run test (104 passed incl. 15 mote_arm), pixi run lint all green; xacro generates correctly with the arm on (real) and off (sim).
NOT verified on hardware — needs Michael at the bench (runbook: mote_arm/BENCH.md). Bench must resolve 3 open items the design already supports both ways: (1) does the arm share the wheel bus or have its own USB adapter (set arm.port accordingly), (2) real servo IDs, (3) udev serial. The robot.yaml soft limits / home / invert are conservative PLACEHOLDERS to calibrate at the bench.
GitHub #2 (camera doesn't fit with the arm attached) noted as an unresolved mechanical clash, not addressed here; mote_arm is not part of mission bringup and is run explicitly.