free-humanoid-centaur

Prior Art Index — Free Humanoid Centaur

This document maps every load-bearing design choice in the centaur morphology to specific entries in the Free Humanoid Corpus. Each entry is cited by its corpus id. Anyone reviewing this morphology — including USPTO examiners and invalidity-contention attorneys — can use this index to locate the specific defensive publications that anticipate any patent claim against the platform’s architecture.

The corpus has 291 entries (as of 2026-05-06) spanning -250 BCE (talos-bronze-giant) to 2025. This index cites the entries that are most directly load-bearing for the centaur morphology.

The bipedal sibling Free Humanoid Platform is the canonical statement for the upper-body subsystems (kinematic topology of the arms, hands, head, torso; actuator distribution at shoulder, elbow, wrist, hand; sensing at every link; the safety-supervisor architecture; the compute architecture; the learning-policy stack). The wheeled sibling Free Humanoid Wheeled is the canonical statement for the hot-swap battery commons interface and the shoal cartridge-swap protocol surface. This document recapitulates those subsystems in summary form and adds the quadruped-base-and-mode-switching-specific subsystems (1, 2, 6, 9 below).

Subsystem 1 — Quadruped-base topology (4 legs × 3 DoF)

1.1 Modern dynamic / industrial quadrupeds (the substrate)

Corpus id Year Shielding
mit-cheetah 2009 MIT Cheetah 1: foundational QDD-quadruped lineage origin. 17-year prior art on dynamic quadruped locomotion.
mit-cheetah-2 2014 MIT Cheetah 2: Wensing 2017 T-RO foundational actuator-design disclosure. 12-year prior art.
mit-cheetah-3 2018 MIT Cheetah 3: blind locomotion across stairs and rough terrain.
mini-cheetah 2019 MIT Mini-Cheetah: open QDD reference, the most-cited modern QDD quadruped anchor.
cheetah-cub-epfl 2013 EPFL Cheetah-Cub: open-source bio-inspired quadruped with CPG control. The open-source quadruped anchor.
anymal 2016 ETH ANYbotics ANYmal: industrial quadruped lineage origin. 10-year prior art on industrial quadruped service robots.
anymal-d-eth-rsl-2022 2022 ETH/ANYbotics ANYmal-D, sim2real era. Modern industrial quadruped anchor.
hyundai-boston-dynamics-spot 2015 Boston Dynamics Spot: commercial quadruped, hot-swap battery, IP-rated outdoor deployment. 11-year prior art.
ghost-robotics-vision-60 2018 Ghost Robotics Vision 60: commercial quadruped, second commercial wheel-leg-hybrid anchor.
hwangbo-anymal-sim2real 2019 Sim-to-real RL for quadruped locomotion; anchors the leg-mode learned-policy choice.
spot-fuel-cell 2024 Spot fuel-cell variant — shielding for any extended-endurance power architecture if added later.

1.2 Foundational legged-vehicle prior art

Corpus id Year Shielding
ge-walking-truck 1968 General Electric’s hydraulic Walking Truck. 58-year prior art on legged loadbearing vehicles. Foundational for any legged-platform-with-payload claim.
raibert-hopping-1leg 1983 Marc Raibert’s one-leg hopper: foundational dynamic-balance disclosure. 43-year prior art. Anchors the balance-margin invariant.
mcgeer-passive-walker 1990 Tad McGeer’s passive-dynamic walker: energy-efficient passive-stable walking. 36-year prior art.

1.3 Mythological and fictional anchors for legged guardian + composite-form humanoid

Corpus id Year Shielding
talos-bronze-giant -250 BCE The deepest fictional / mythological anchor in the corpus for a legged guardian humanoid. The Talos myth disclosed an autonomous leg-based humanoid 2200+ years before any modern academic patent claim could possibly anticipate it. For a quadruped+humanoid composite, the Talos anchor is read for its “legged + autonomous + service-deployed” properties.
gundam-rx-78-2 1979 RX-78-2 Gundam: 47-year fictional anchor for piloted humanoid leg-base mecha; reads as composite-form prior art for a humanoid torso on a non-bipedal locomotion base.
mazinger-z 1972 Mazinger Z: 54-year fictional anchor for piloted humanoid mecha with leg-form locomotion.

A dedicated centaurs-greek-myth corpus entry would be the most pointed fictional anchor for this morphology family but does not currently exist in the corpus. Recommended future corpus addition flagged in docs/. Until that entry exists, talos-bronze-giant and the piloted-mecha lineage carry the fictional shielding.

Implication: quadruped-base humanoid platforms for service deployment in environmental-remediation / disaster-response / agricultural / civil-infrastructure environments are fully exhausted as patentable subspace. Any patent claim issued post-2010 on a “quadruped humanoid for service tasks” is anticipated by at least three academic entries (anymal, mit-cheetah-2, hyundai-boston-dynamics-spot) plus a 58-year-deep legged-vehicle academic anchor (ge-walking-truck) plus a 2200+-year-deep mythological anchor (talos-bronze-giant).

Subsystem 2 — Wheel-leg-hybrid foot

2.1 Wheel-leg architecture

Corpus id Year Shielding
anymal-wl (in OpenLoco quadruped corpus) The canonical wheel-leg-hybrid reference. ANYbotics’ wheel-on-leg variant of ANYmal documents the four-leg + powered-wheel-foot composition this morphology inherits. The mode-switching architecture (hard transition between wheel and leg) is shielded directly here.
ghost-robotics-vision-60 2018 Ghost Robotics Vision 60: second commercial wheel-leg-hybrid anchor in the corpus.

The combination (wheel-leg hybrid + 120 kg + 50 kg payload + IP67 wetland deployment) is genuinely novel original engineering at this mass class. The architectural pattern itself is shielded; the load-bearing physical realization is the work flagged in ARCHITECTURE §5.

2.2 Wheel actuator (QDD)

Corpus id Year Shielding
mit-cheetah-2 2014 Foundational QDD architecture.
mini-cheetah 2019 Open MIT QDD reference.
mjbots-moteus 2019 Foundational prior art for compact open BLDC controllers in legged robotics. CAN-FD interface.

2.3 Leg-joint actuator (cycloidal reducer)

Corpus id Year Shielding
anymal 2016 ANYmal’s industrial-grade hip/knee actuator architecture.
anymal-d-eth-rsl-2022 2022 Modern ANYmal-D actuator architecture.
sumitomo-cyclo 1937+ Cycloidal-reducer prior art, deeper than any modern humanoid claim.

TBD (architectural call): cycloidal vs. harmonic-drive at the leg joints. Cycloidal is more shock-tolerant and less expensive at the centaur’s torque class; harmonic-drive is more compact and back-drivable. v0 commitment is cycloidal; the harmonic-drive variant is held as a future descriptor variant. See ARCHITECTURE §2.2.

Subsystem 3 — Upper-body kinematic topology

Inherited from Free Humanoid Platform prior-art INDEX, Subsystem 1. Summary:

Corpus id Year Shielding
wabot-1 1973 Foundational anchor for full-scale anthropomorphic humanoid kinematic topology.
honda-e0–honda-e6 1986–1993 Honda E-series chain. Anchors arm + torso topology.
honda-p1, honda-p2, honda-p3 1993–1997 Honda P-series. Anchors balance and ZMP.
asimo, hubo, hrp-2–hrp-5p 2000–2018 Mass-produced humanoid lineage.
nasa-valkyrie, robonaut-2, pal-talos 2011–2017 Industrial / NASA full humanoids.
darwin-op, poppy-humanoid, inmoov, reachy 2010–2020 Open-source small/desk humanoid lineage.
unitree-h1, unitree-g1, berkeley-humanoid, k-scale-os 2023–2024 Recent academic / commodity humanoid disclosures.

For the centaur morphology, the bipedal-leg subset of this chain is dropped (no cassie-osu, digit-meta, atrias); the arm/hand/torso/head subset is preserved.

Subsystem 4 — Upper-body actuators

Inherited from Free Humanoid Platform prior-art INDEX, Subsystem 2, with the bipedal-leg-actuator chain dropped and replaced by the quadruped-leg cycloidal chain (Subsystem 2.3 above). Summary of upper-body actuator chains:

4.1 Harmonic-drive (shoulder, elbow)

Corpus id Year Shielding
honda-e0 1986 First disclosed harmonic-drive use in a humanoid. 40-year prior art.
dlr-toro 2014 Torque-controlled humanoid; harmonic-drive disclosure.
asimo, hubo, hrp-2–hrp-5p, robonaut-2, pal-talos, nasa-valkyrie 2000–2018 Full chain.

4.2 Tendon-driven (wrist, hand)

Corpus id Year Shielding
shadow-dexterous-hand 2002 24-year prior art on tendon-routed anthropomorphic hand.
dlr-hand-ii 2001 DLR’s dexterous hand.
dlr-justin 2009 DLR’s tendon-arm chain.
pisa-iit-softhand 2012 Underactuated soft hand (synergy-based). The recommended-hand anchor.

4.3 QDD (neck, waist, wheel-feet)

Corpus id Year Shielding
mit-cheetah-2, mini-cheetah 2014, 2019 QDD architecture.
mjbots-moteus 2019 Open BLDC controller.

Subsystem 5 — Sensing

Inherited from Free Humanoid Platform prior-art INDEX, Subsystem 3, plus the quadruped-and-outdoor-specific additions:

Corpus id Year Shielding
pomerleau-alvinn 1989 Camera-to-control.
howe-cutkosky-tactile-1989 1989 Robotic tactile sensing.
biotac-syntouch 2008 Multimodal fingertip tactile.
gelsight 2009 High-resolution optical tactile.

5.2 Outdoor and quadruped-specific additions

Corpus id Year Shielding
dlr-justin 2009 Lidar-equipped wheeled humanoid; tilt-supervised drive. (Cross-cited from the wheeled sibling’s outdoor-sensing chain.)
pr2 2010 Lidar additions to wheeled mobile manipulator.
hyundai-boston-dynamics-spot 2015 Outdoor IP-rated quadruped lidar mobile platform.
anymal 2016 Per-leg IMU and per-foot F/T sensor pattern.
mit-cheetah-2 2014 Per-leg IMU pattern.

GPS, 5G modems, and acoustic-receivers in robots are commodity and not patent-thicket-dense; corpus shielding is light because the design choices are obvious-and-universal rather than novel-claimed. The JANUS-receiver pattern is shielded by shoal ARCHITECTURE §4.

Subsystem 6 — Safety supervisor (with quadruped-specific invariants)

The safety supervisor architecture is inherited verbatim from Free Humanoid Platform prior-art INDEX, Subsystem 5 — the deepest chain in the corpus, 80+ years of fictional anticipation plus 30 years of formal academic prior art. Summary chain:

Corpus id Year Shielding
frankenstein 1818 Earliest fictional anchor.
rur-rossums-robots 1920 Three-Laws-anticipating constraint failure.
asimov-positronic-robots 1940 Three Laws. 86-year fictional anchor.
williamson-folded-hands 1947 Safety-constraint failure mode.
forbidden-planet-robby 1956 Three-Laws-compliant fictional disclosure.
magnus-robot-fighter 1963 Mass-produced civic-deployed humanoid.
b-9-lost-in-space 1965 Hazard-warning humanoid.
hal-9000 1968 Supervisor failure modes.
silent-running-drones 1972 Maintenance drones with task-bound autonomy.
asimovs-zeroth-law 1985 Extension of Three Laws.
data-tng 1987 Self-aware constraint adherence.
robocop-1987 1987 “Prime Directives” as Simplex-anticipating disclosure.
sherman-simplex-architecture 1995 Foundational academic. Verified safety controller as fallback.
iso-10218-collaborative-robots 2006 Industrial standards anchor.
reachability-analysis-safe-control 2005 Formal-method safe set computation.
control-barrier-functions 2007 Modern formal safety-controller standard.
runtime-assurance-rta 2010 AFRL Simplex-to-flight-control bridge.
shielding-rl 2018 Formal safety on learned policy.

Quadruped-specific invariants

The bipedal supervisor adds five invariants for the centaur morphology — slope tilt 30°, foot-fall validation, balance-margin hard-stop, leg-collision avoidance, mode-transition gate. Their additional shielding:

Corpus id Year Shielding
anymal 2016 Foot-fall validation, balance-margin, leg-collision avoidance — all standard ANYmal supervisor invariants.
anymal-d-eth-rsl-2022 2022 Modern ANYmal-D supervisor invariants including slope-tilt thresholds.
hyundai-boston-dynamics-spot 2015 Commercial quadruped supervisor invariants — the slope-tilt and balance-margin thresholds are shielded against Spot’s reported operational envelope.
mit-cheetah-2 2014 Balance-margin hard-stop pattern in dynamic-quadruped operation.
raibert-hopping-1leg 1983 Foundational dynamic-balance prior art for the balance-margin invariant.
hwangbo-anymal-sim2real 2019 Foot-fall validation in learned-policy quadruped operation.
anymal-wl (in OpenLoco quadruped corpus) Mode-transition gate shielding — the canonical reference for the hard-mode-switch architecture between wheel and leg modes.
ghost-robotics-vision-60 2018 Second commercial reference for the mode-transition gate.

Subsystem 7 — Compute and learning policy

Inherited from Free Humanoid Platform prior-art INDEX, Subsystem 4. Joule SOM as recommended-default within an abstract HAL. Imitation-learning-from-teleop manipulation policy. Locomotion policy is centaur-specific (dual-mode: skid-steer in wheel mode, MPC + sim2real RL in leg mode).

Corpus id Year Shielding
act-aloha, mobile-aloha, diffusion-policy 2023–2024 Imitation learning.
openai-rt-2, open-x-embodiment, physical-intelligence-pi-zero, skild-foundation-model, covariant-rfm 2023–2024 VLA foundation models (optional upgrade path).
hwangbo-anymal-sim2real 2019 Sim-to-real RL for quadruped locomotion (leg mode).

For wheeled-mode skid-steer locomotion control, the standard skid-steer literature plus anymal-wl and ghost-robotics-vision-60 shield the choice fully.

Subsystem 8 — Comms

Inherited from Free Humanoid Platform prior-art INDEX, Subsystem 6, plus the wheeled sibling’s 5G and JANUS-receiver additions (cross-cited verbatim — same kit, same shielding). ROS 2, CAN-FD, gRPC, WebRTC, WiFi 6, 5G, JANUS-receiver. None patent-thicket-dense.

Subsystem 9 — Mission integration with shoal dock-A

This subsystem largely mirrors the wheeled sibling’s Subsystem 9. The cartridge-swap, waste-hopper retrieval, and biology-reservoir handshake patterns are protocol-identical to dock-B. The differences are deployment-context:

Element Corpus shielding
Cartridge-swap protocol (manipulation surface) dlr-justin (mobile manipulation), shadow-dexterous-hand, pisa-iit-softhand (underactuated grasp). Protocol identical to wheeled sibling.
Waste-hopper retrieval (manipulation surface) dlr-justin, anymal-d-eth-rsl-2022 (quadruped + extended-reach manipulation precedent).
Biology-reservoir handshake (comms protocol) shoal ARCHITECTURE §4 — the dock-burst optical protocol.
dock-A wetlands traversal Genuinely novel — no direct corpus shielding for the cross-product of (quadruped + IP67 + wetland substrate + autonomous benthic dock). Element-by-element shielded by hyundai-boston-dynamics-spot (IP-rated outdoor quadruped) + bigdog (rough-terrain quadruped) + the wetland-traversal robotics literature, but not as a composition. This is the load-bearing original engineering enumerated in ARCHITECTURE §5.
JANUS-receiver coordination (acoustic comms) shoal ARCHITECTURE §4 plus the broader JANUS-protocol corpus tag. Especially relevant at dock-A because shoal fish may be operating in the same body of water.

The mission-integration protocol stack itself (cartridge-swap, waste-hopper retrieval, biology-reservoir handshake) inherits from the wheeled sibling’s original-engineering surface; the centaur’s load-bearing original work is the wetland-traversal portion of the integration.

Subsystem 10 — Mode-transition gate (centaur-specific)

This subsystem is centaur-specific — neither the bipedal nor the wheeled sibling has a mode-switching architecture. The hard-mode-switch architectural commitment (#6 in ARCHITECTURE §9) is shielded by:

Corpus id Year Shielding
anymal-wl (in OpenLoco quadruped corpus) The canonical reference for hard-mode-switch wheel-leg-hybrid quadrupeds. Both at the architecture level and at the supervisor-invariant level.
ghost-robotics-vision-60 2018 Second commercial confirmation.

The supervisor-invariant implementation (formal specification + verification in MathGround) is genuinely novel original engineering at the open-source level — the cited prior art is closed-source commercial — and is enumerated in ARCHITECTURE §5.

How to use this index

When you make a design choice in the platform — adding a feature, picking a vendor, modifying the descriptor, or writing a new firmware module — locate the relevant subsystem in this index and cite the most specific corpus entry that anticipates the choice.

If the corpus does not yet anticipate your choice:

  1. Check the corpus directly (corpus.jsonl).
  2. If still no anticipation, propose a new corpus entry (per the corpus’s CONTRIBUTING.md).
  3. If neither is possible, mark the design choice draft in the descriptor or architecture and document the invalidation gap.

Recommended future corpus additions flagged by this morphology:

Every commit that introduces a load-bearing design choice should reference at least one corpus entry id by name in the commit message. This is the operational form of the governance posture in README.md and CONTRIBUTING.md.

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