An open hardware, open firmware, open data humanoid AUV reference design — the fourth morphology in the OpenIE humanoid family alongside the bipedal Free Humanoid Platform, the wheeled Free Humanoid Wheeled, and the centaur Free Humanoid Centaur. A bimanual humanoid upper body on a negatively-buoyant 8-thruster vectored pod, targeted at subsurface service work: shoal dock-A subsurface and underwater rake-array / intake-screen / bilge-line / hull-mating maintenance. Shielded by the Free Humanoid Corpus.
Status: scaffold (v0.0). This repository establishes the morphology's positioning and architectural commitments. It is not yet a buildable robot. The architectural decisions are resolved in ARCHITECTURE.md §9; each commitment is shielded by a corpus-cited prior-art chain. Detailed CAD, vendor-pinned BOM, and physical-build documentation are Phase 1+ deliverables.
Free Humanoid Submersible is the fourth morphology in the OpenIE humanoid family. It inherits the bipedal sibling's torso, arms, hands, head, sensing-of-the-upper-body, compute, manipulation stack, and safety supervisor architecture verbatim. It replaces the bipedal legs (and the wheeled sibling's wheeled-base, and the centaur's wheel-leg-hybrid quadruped base) with a negatively-buoyant streamlined underbody equipped with eight vectored thrusters that provide full 6-DoF station-keeping for in-water station-static manipulation. There are no legs, no wheels, and no contact with a hard ground plane during operations — buoyancy and thrust-vectored propulsion handle the locomotion task.
The design domain is the body of water itself, below the waterline. Anywhere a wheeled or legged humanoid cannot operate because the operating environment is fluid, but where bimanual dexterous manipulation is the load-bearing capability the platform must deliver.
The project sits at the intersection of five projects:
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OpenLoco — the substrate. The platform compiles from a single UDD JSON file to URDF, MJCF, STL, BOM, and assembly through OpenLoco. The submersible is a
humanoid_submersiblemorphology in the same compiler. Genesis MPM/fluid backends extend the simulation envelope below the waterline. -
Free Humanoid Corpus — the prior-art commons. Every non-trivial design choice cites a specific corpus entry, the same governance posture as the three sibling morphologies.
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Free Humanoid Platform — the bipedal sibling, the upper-body donor. The 21-DoF upper body of this morphology is the upper body of the platform; this repo cross-links rather than duplicates that work. One upper body, four lower bodies.
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Free Humanoid Wheeled and Free Humanoid Centaur — the other sibling morphologies. Submersible inherits the wheeled sibling's hot-swap battery commons (adapted for pressure-balanced subsea Li-ion) and the centaur's outdoor-rugged sensing posture (further adapted for through-water acoustic comms).
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shoal — the deployment partner. Submersible is designed against the shoal dock-A subsurface service mission: maintenance of subsurface rake arrays, intake screens, bilge lines, and hull-mating fixtures at autonomous benthic docks. See shoal ARCHITECTURE.
| Quantity | Bipedal | Wheeled | Centaur | Submersible |
|---|---|---|---|---|
| Locomotion | 2 legs | 2 wheels + casters + tower | 4 wheel-leg legs | 8 vectored thrusters |
| Operating medium | Air, on hard ground | Air, on paved ground | Air, on rough ground | Submerged — fresh / brackish / salt water |
| Total mass (in air) | ~50 kg | ~70 kg | ~120 kg | ~80 kg (slightly negatively buoyant in water) |
| Sustained payload (in water, at extended reach) | n/a | n/a | n/a | 5 kg |
| Operating depth | n/a | n/a | n/a | 0–50 m (Phase 2 target) |
| Endurance | 4–6 h | 4–6 h | 4–6 h | 3–5 h on battery; tethered ops indefinite |
| Comms | WiFi / 5G / CAN-FD | + JANUS-receiver | + JANUS-receiver | Acoustic (JANUS) + tether (Ethernet) |
| Mission domain | Indoor service | Paved outdoor (dock-B) | Wetlands (dock-A surface) | Subsurface (dock-A subsurface, hull / screen / rake) |
The deployment line is paved indoor → bipedal or wheeled; paved outdoor → wheeled; rough or wet → centaur; submerged → submersible. The four morphologies cover every mode-domain the shoal water-remediation mission needs.
Shoal docks (per shoal ARCHITECTURE) include benthic and partially-submerged maintenance surfaces that have to be serviced underwater: rake arrays that catch macro-debris, intake screens that bias the dock's flow, bilge / outflow lines, and hull-mating fixtures the dock uses to dock-and-charge shoal fish. These surfaces require bimanual dexterous manipulation underwater — the same use-case the centaur handles above the waterline at dock-A surface.
The subsurface use cases, in priority order:
- shoal dock-A subsurface service. Rake-array clearing, intake-screen brushing, bilge-line inspection, hull-mating-fixture maintenance at autonomous benthic docks deployed in remote rivers, marine, and wetlands sites.
- Marine infrastructure inspection. Pier piling inspection, mooring-line attachment, hull cleaning, intake-screen maintenance at marinas, harbors, and small-craft moorings.
- Submerged search-and-recovery. Dropped-tool recovery, lost-equipment recovery, environmental-sample collection at mid-depth (≤ 50 m).
- Aquaculture infrastructure service. Net-pen inspection, mooring-fixture maintenance at small-scale aquaculture sites.
The platform is not designed for deep-water service (depth target is 50 m at v0.2, well above oceanographic deep-water depths) and is not designed as an oceanographic research instrument (mass-spec / CTD / acoustic-doppler instrument suites are out of scope). It is a maintenance-and-manipulation tool sized for the shoal mission band.
A standard ROV is a thruster pod with a parallel-jaw or tooled manipulator on a single arm — adequate for grasp-and-cut tasks but not for the dexterous bimanual work the shoal docks require (e.g., rake-bar threading, intake-screen rebinding, fastener-by-fastener servicing of a hull-mating fixture). The same use-case argued for a humanoid centaur above the water — bimanual dexterous manipulation in a service-task envelope — argues for a humanoid AUV below it.
The four-morphology family thesis reinforces this: one upper body, four lower bodies. Reusing the bipedal humanoid's upper body across all four morphologies means the same descriptor, the same hand, the same imitation-learning manipulation policy, the same wrist + tactile fingertip stack, and the same safety supervisor invariants for the manipulation layer all work below water as well as above. The submersible is the most extreme test of the descriptor-share thesis: same arms, same hands, completely different lower body and operating medium.
Prior art for humanoid AUVs:
- Aquanaut (Houston Mechatronics, 2017) — humanoid-arm-equipped AUV with a hovering-pelvis form factor. The strongest commercial prior-art anchor for a humanoid-arm thruster-pod AUV.
- OceanOne / Ocean OneK (Khatib lab, Stanford, 2016 / 2022) — bimanual humanoid teleop AUV with anthropomorphic upper body. The strongest academic prior-art anchor for a humanoid-form free-floating manipulation platform.
Both are corpus-additions-recommended; neither is a closed-source-only platform that forecloses a humanoid AUV with an open descriptor and an open thruster pod.
| Quantity | Target | Notes |
|---|---|---|
| Total system mass (in air) | ~80 kg | 30 kg pressure-hull thruster pod + 50 kg upper body (bipedal sibling's 50 kg, with submerged-rated wrist seals) |
| Net weight in fresh water | ~+2 kg negatively buoyant | Slight negative buoyancy + thrust-active station-keeping — descend on power-off, ascend by thrust |
| Battery capacity (subsea Li-ion) | 2 kWh primary + 0.2 kWh UPS | 3–5 h endurance on battery alone; tethered ops indefinite |
| Operating depth (Phase 2) | 50 m | 6061-T6 aluminum hull, double-O-ring seals, Delrin endcaps |
| Thruster count / layout | 8 thrusters | 4 horizontal vectored + 4 vertical = full 6-DoF station-keeping (ROV-class layout) |
| Sustained in-water payload at extended reach | 5 kg | Limited by thruster station-keeping authority during one-handed work |
| Comms | JANUS acoustic + Ethernet tether | Acoustic for untethered ops; tether for dock-coupled high-bandwidth ops |
These numbers are scaffold targets, not validated specifications. Iterating them against a physical pressure-hull build, the thruster-pod architectural call (8-thruster vs. 6-thruster), and the shoal dock-A subsurface protocol is the Phase 1 → Phase 2 deliverable.
Same as the three sibling morphologies, with the same release-blocker note on canonical license-text inlining:
| Artifact class | License | Files |
|---|---|---|
| Hardware (CAD, schematics, PCB layouts, pressure-hull and thruster-pod mechanical designs) | CERN-OHL-S 2.0 | LICENSE-HARDWARE |
| Firmware, control software, simulation, tools | Apache 2.0 | LICENSE-SOFTWARE |
| Documentation | CC-BY-SA 4.0 | LICENSE-DOCS |
| Descriptors (UDD JSON), datasets, BOM data | CC0 1.0 | LICENSE-DATA |
CC0 on the descriptor is the load-bearing license choice. The license files in this repo currently contain SPDX-tagged headers; inlining the canonical text is a release-blocker before any public push.
- Phase 0 — scaffold (this repo, current). README, ARCHITECTURE, descriptor stub, sim/control/firmware/chassis stubs.
- Phase 1 — descriptor + sim model (target 2026-Q3). Iterate the UDD descriptor to a state where the OpenLoco compiler emits a Genesis-fluid + MuJoCo-rigid model that station-keeps in simulated water and performs a simulated rake-bar manipulation under fluid load.
- Phase 2 — pressure hull + thruster pod (target 2026-Q4). First physical pressure-hull + thruster-pod prototype, dry-bench testing of thruster control authority and pressure-cycle of the hull seals.
- Phase 3 — pool trial (target 2027-Q1). Tethered pool trial of the integrated platform with bipedal upper body, with manipulation-static at depth.
- Phase 4 — open-water shoal dock-A trial (target 2027-Q2). First open-water deployment at a partner shoal dock-A site.
- Free Humanoid Platform — bipedal sibling, upper-body donor.
- Free Humanoid Wheeled — wheeled sibling, hot-swap battery commons donor.
- Free Humanoid Centaur — centaur sibling, the surface-side wetlands counterpart of this morphology's subsurface mission.
- shoal — water-remediation deployment partner. dock-A subsurface mission target.
- Free Humanoid Corpus — prior-art shielding commons.
free-humanoid-submersible/
README.md this file
ARCHITECTURE.md canonical full-system spec, prior-art-cited
LICENSE-HARDWARE CERN-OHL-S 2.0
LICENSE-SOFTWARE Apache-2.0
LICENSE-DOCS CC-BY-SA-4.0
LICENSE-DATA CC0-1.0
descriptor/ UDD descriptor — source of truth
free-humanoid-submersible.udd.json
README.md
chassis/ trunk, arms-shared, hands-shared, thruster-pod, buoyancy, pressure-hull, penetrators, comms-module
sim/ Genesis (primary, fluid/MPM) + MuJoCo (rigid-body), Stonefish, Drake/Gazebo/Isaac tertiary
control/ thrust allocation, station-keeping, depth/heading, manipulation hand-over
firmware/ HAL (shared with bipedal at low level), thruster-ESC layer, depth/IMU layer, supervisor invariants
docs/ design notes beyond root README/ARCHITECTURE
Each subdirectory has its own README.md scoped to its concern.
- ARCHITECTURE.md — canonical full-system spec.
- descriptor/free-humanoid-submersible.udd.json — UDD source of truth (v0.0 stub).
- Free Humanoid Platform ARCHITECTURE.md — for everything inherited (upper body, sensing, compute, safety, manipulation, learning policy).
- Free Humanoid Centaur ARCHITECTURE.md — for the descriptor-substitution-of-lower-body pattern this morphology follows.
- shoal ARCHITECTURE.md — for the dock-A subsurface mission integration target.