The HopeJR specs

Caveats · stated by the package

• Upstream pins: TheRobotStudio/HOPEJr@0a60df1e326b092436edfb011b833fb9a3bc397b (main, 2026-05-04; last change: Robstride RS02 test STL, 2026-04-30). Arm/README.md dated 26/06/2025 (Hugging Face arm, hand and Homunculus teleop); Humanoid/README.md dated 02/07/2025; ChangeLog last entry v0.1.8 2024-12-02. LeRobot docs/source/hope_jr.mdx and src/lerobot/robots/hope_jr at huggingface/lerobot@e624f3f7f8411ec3a02635d06e79373341e5ef35 (2026-09-24).
• Scope: this package builds ONE arm + dexterous hand and its Homunculus exoskeleton + glove (the Arm/ directory). The full 66-DOF humanoid is not buildable from upstream: Humanoid/ has a right-leg + pelvis URDF (Onshape export referencing Cybergear and SM85BL actuators and SEA springs), a 2-file first-draft torso (chest, mantle), a legs STEP that is a Git LFS object (HJr_Legs_07k.zip is ~234 MB), and a single Robstride RS02 SEA spring/motor mount test STL (2026-04-30). No BOM, actuator list, electronics or assembly guide exists for legs, pelvis or torso.
• No assembly guide: Arm/README.md describes design changes only. Every assembly step here is reconstructed from BOM placement notes, STEP files and LeRobot motor maps; torques, times and print settings are not published.
• Print material, layer height, infill and supports are not stated anywhere for the Arm/ STLs. The arm STLs are large multi-body files (e.g. right_hand.stl ~10.6 MB); the number of spool covers needed is not stated.
• Servo mix conflicts: Arm/BOM.md lists 1 SM8512BL + 2 STS3250 + 4 STS3215 (12 V); LeRobot hope_jr_arm.py declares SM8512BL + 6 STS3250 (including all wrist joints); Humanoid/README.md and the Second_Arm_Draft BOM (older HOPELite arm) say 4 STS3250 + 3 STS3215 and plan to move to STS3250 for all shoulder/elbow joints. The BOM.md mix is used here.
• BOM units are loose: bearing headers say 'width x inner x outer' but values read as inner x outer x width (e.g. 20x27x4, 6x10x3); the robot side lists 18 x 20x27x4 bearings while the older arm BOM says 17. Spring wire (0.3 mm) differs from the older hand BOM (0.4 mm).
• PCB quantities are not stated: which boards (12-connector, 7-connector, Homunculus) and how many per build is inferred (one Homunculus board each for exo and glove). The 12-connector bom.csv has no LCSC part number. JLCPCB PCBA ordering needs an account and has minimum quantities.
• No USD prices anywhere upstream. Two EUR figures appear only inside AliExpress URL parameters (URT-1 EUR 8.89, fishing line EUR 16.19). The earlier '~$3,000' full-humanoid target is not backed by a BOM.
• Most vendor links are amzn.eu / amazon.fr / fr.aliexpress short links from a French build; availability outside the EU is unverified and short links can die. Alibaba listings are Feetech product pages with MOQ pricing.
• Licensing: the GitHub license API reports none for the repo. Humanoid/LICENSE is Apache-2.0 text prefixed with 'Copyright 2024 The Robot Studio. All rights reserved.' and sits only in Humanoid/; the Arm/ directory (the buildable HF arm, hand, exo, PCBs and code) carries no license of its own, so its reuse terms are unclear. LeRobot drivers are Apache-2.0. Project Homunculus (origin of the glove/exo) has no license either.
• Teleop firmware ships as .cs files that are actually Arduino C++ sketches; no build instructions, board definition or pin diagram accompanies them. exo.cs computes only 5 angles while LeRobot's homunculus_arm expects 7 joints; the exact exo firmware LeRobot expects may live in the Project Homunculus exo submodule instead.
• Record/replay/train are marked experimental in the LeRobot docs and only demonstrated on the hand; no published HopeJR policy checkpoint. Arm and hand teleop must run in separate processes.
• Upstream docs are stale in places: Humanoid/README.md and ChangeLog (last v0.1.8, 2024-12) predate the Hugging Face Arm/ release; Arm/README says STLs are in '3dprint files/STL' but the folder is '3dprint files/arm' and '/exoskeleton'. Community support is via WhatsApp/Discord links in the READMEs.