Bills of materials

EBOM, MBOM and SBOM generated from the kinematics and checked against each other; approved manufacturer list with source and price where verified

Open on GitHub Mở trên GitHub

Snapshot of this document in the GEMs repository. The repository itself is the current version. Bản chụp tài liệu này trong repo GEMs. Bản đang chạy nằm ở chính repo.

The three bills of materials of the GEMs reference design, in the form hardware teams use:

• EBOM — engineering BOM: the product as designed, a multi-level structure.
• MBOM — manufacturing BOM: the same parts regrouped into routings — build operations at work centres — plus the consumables the design never shows.
• SBOM — software BOM, in two senses the industry uses side by side: software images carried as virtual part numbers in the EBOM, so a shipped body records what it runs; and a machine-readable component inventory in CycloneDX, for supply-chain security.

To read them, open EBOM.md and MBOM.md. The CSV and JSON files are the data; those pages are generated from them.

python hardware/bom/build_bom.py            # regenerate
python hardware/bom/build_bom.py --check    # verify only; non-zero on any error

Python 3, standard library only. This is work package B of plan/.

Why this shape

A flat list of what the specification names is a requirements list, not a BOM. Industry practice, and the open humanoid projects that publish theirs, converge on a few features, and each one is here for a reason.

Columns

parts.csv — part_number, rev, description, category, make_buy, uom (EA, SET, M2), unit_mass_kg and mass_basis, maturity (TM or LAB, as in spec 00), design_level (L0–L5, as in plan/), lifecycle (all CONCEPT until a design is released), spec_ref, requirement, notes.

ebom.csv — parent, find_no (10, 20, 30… per parent), child, qty, qty_basis (required when qty is empty), ref_des (for PCBA lines, once they exist), notes.

avl.csv — part_number, rank, status, manufacturer, mpn, supplier, supplier_pn, source_url, unit_price, currency, price_qty (the order quantity the price is for), price_date, price_url, notes.

Rules the check enforces

• Every part is used by an assembly, every line points at a part, and the structure has no cycles.
• An empty quantity carries a basis saying why it is empty.
• A price carries all of its currency, order quantity, date and page. A price that cannot be re-checked is refused.
• A SELECTED AVL entry carries a manufacturer, a manufacturer part number and a source.
• A LAB part carries no manufacturer part number: none exists to give.
• The generated files match what the generator produces now.

MBOM

Routings are generated for every assembly and every PCBA that carries software. Leaf parts — machined, composite and bought-in — have no routing here; theirs is fabrication to drawing, and belongs with the drawing.

Commissioning is a work centre of its own because the specification makes it one: attestation tier 2 compares a body against the fingerprint taken here, so a body that skips it cannot be attested later.

Consumable quantities are "as consumed" and set by work instructions, which do not exist yet. Cycle times and labour are not estimated.

SBOM

sbom.cdx.json lists the software that exists in this repository: each module with its SHA-256, licence, supplier and the modules it imports, and the Python interpreter they all run on. There are no third-party packages. Its version field is a content hash, so a changed file is a changed version, and the check fails until the SBOM is regenerated. The timestamp is set at generation and is the one field the check ignores.

The firmware images and the edge module's OS image are in the EBOM as virtual parts but not in the SBOM, because none of them has been built. They join it when they exist — with the RTOS, the EtherCAT master stack and the operating system distribution as the third-party components they will bring, each with its licence to be checked against this repository's.

Where it stands

The summary at the top of EBOM.md is the current count. At the time of writing: 296 part numbers, including 10 software images and 6 consumables; 497 operations across 60 routings; one selected manufacturer part (the Jetson T5000 module), candidates for seventeen parts, one verified price (the AKH70-16, on eight candidate lines), and a mass roll-up of 44.2 kg out of the 96.2 kg budget — the rest is blank rather than guessed.

Prices were looked for on 2026-09-26. Most supplier pages were unreachable from the environment this was written in, so the AVL rests on search results and on the pages that could be read, and each entry's notes say which.

What building it turned up

The actuator density has one motor behind it, at two ratios. At 16:1 the module peaks at 78 Nm and 10 of the 18 joint types — 17 of the 31 joints — need more. At 48:1 the same motor peaks at 222 Nm and only hip pitch, knee and trunk pitch fall short, by 4–8 Nm, at about a third of the output speed; both are in the AVL, and whether the slower one is fast enough is D-2's question.

The reducer classes and the actuator family disagree. hardware/mechanical §2 assigns cycloidal reducers to hips and knees and harmonic drives to wrists and neck; hardware/electrical §2 selects a hollow-shaft planetary module for every joint. The reducer rows carry the conflict until D-2 decides.

Ankle and waist have no reducer class. The mechanical table stops at hip, knee, shoulder, elbow, wrist and neck.

References