Purpose: define a manufacturable, modular CAD “archetype” (envelope + interfaces + bays + fastener grid + harness + thermal + serviceability) so multiple teams can design parts that converge to one scalable platform (Model-T principle).
1) Design Objectives
Primary objectives
- Standardization: fixed envelopes + repeatable mounting + common connectors.
- Modularity: hot-swappable subassemblies (compute, power, actuation, skin).
- Serviceability: tool access, fast replacement, diagnostic ports.
- Scalability: ZT-1 → ZT-10 variants share the same “hard points”.
- Manufacturability: parts optimized for CNC + sheet metal + injection/compression molding + additive where justified.
- Safety & governance: physical segregation of critical systems (SEC/GOV/SAFE) in dedicated protected bay.
Non-functional constraints
- Maintainable with standard tools (hex/Torx) + minimal custom jigs.
- No single module replacement requires removing >2 adjacent modules.
- Thermal and power envelopes enforced at the mechanical layout level (ducts, heat paths, isolation).
2) System Family: CAD Envelopes and Variant Logic
Define one Master Envelope and controlled down/up-scales.
2.1 Master Envelope (ZT-10 reference)
- Overall height: 1.72 m (±20 mm)
- Shoulder width: 0.48 m (±15 mm)
- Hip width: 0.36 m (±15 mm)
- Mass target: 78 kg (±12 kg)
- Payload: 15 kg sustained, 25 kg peak (arms)
- Ingress protection target: IP54 baseline; IP65 option kit
2.2 Family scaling (common hard points)
- ZT-1 / ZT-3: same chassis spine, simplified limbs, fewer actuator cartridges.
- ZT-7: reinforced hip/ankle, higher thermal capacity, redundant power.
- ZT-10: full dual-plasticity compute + full sensor skin + redundancy.
Rule: all variants keep the same:
- Spine rail geometry
- Compute bay footprint
- Power bay footprint
- Pelvis + shoulder ring hard points
- Fastener grid and datum scheme
3) CAD Master Coordinate System & Datums
3.1 Coordinate system
- Origin O at pelvis center of rotation (hip midpoint).
- +Z up (head direction), +X forward, +Y left.
3.2 Primary datums
- Datum A: spine rail center plane (XZ)
- Datum B: pelvis ring plane (XY at O)
- Datum C: shoulder ring plane (XY at Z = +620 mm)
All module mounting surfaces reference A/B/C.
4) Structural Architecture (Chassis)
4.1 Core structure: Tri-Frame Spine + Rings
- Spine: modular internal “tri-frame” beam (3 longitudinal members) for torsional rigidity.
- Pelvis ring: closed composite/aluminum ring; load distribution to legs; houses main power bus.
- Shoulder ring: closed ring; houses upper harness junction + thermal manifold branch.
Materials (baseline)
- Spine: 7075-T6 aluminum skeleton + carbon composite outer shear panels.
- Rings: forged aluminum or carbon composite with metal inserts for hard points.
4.2 Hard points (critical)
- HP-P1..P8 around pelvis ring (legs, power bay, spine).
- HP-S1..S8 around shoulder ring (arms, sensor mast, service panels).
- HP-C1..C6 inside thorax for compute bay frame.
- HP-B1..B4 inside abdomen for battery bay frame.
Hard points use metal inserts with helicoils.
5) Module Bay Layout (Industrial “Architecture”)
5.1 Bays (stacked, front/service accessible)
Bay 1 — Compute Bay (thorax, behind sternum panel)
- Houses: NSC, HNL, WMM storage, SEC/GOV enclave (segregated).
- Access: front sternum hatch + two side service hatches.
- Mounting: slide-in cartridge rails + keyed alignment pins.
- EMI: conductive gasket perimeter.
Bay 2 — Power Bay (abdomen, behind “belt” panel)
- Houses: BMS, PMU, primary DC bus, high-current contactors, fusing.
- Access: front belt hatch + underside inspection port.
- Isolation: fire/thermal barrier to compute bay.
Bay 3 — Thermal Bay (back spine cavity)
- Houses: heat exchanger block, pumps (if liquid), duct manifold (if air), phase-change optional.
- Access: rear spine panel.
- Routing: dedicated thermal “trunk line” to compute and joints.
Bay 4 — Sensor Hub Bay (upper chest / collar)
- Houses: time sync, sensor fusion pre-processor, IMU mast, audio.
- Access: collar panel.
Bay 5 — Service & Diagnostic Bay (left flank)
- Houses: DIAG module, debug connector, audit storage physical security.
- Access: lockable door (tamper evident).
6) Compute Bay CAD Specification (Critical)
6.1 Cartridge form factors
Define two cartridge standards:
(A) “C-Tile” Compute Cartridge (NSC / accelerators)
- Size: 240 × 160 × 45 mm
- Mass: ≤ 2.5 kg
- Mount: 4-point rail + 2 dowel pins
- Connector: blind-mate high-speed + power
(B) “H-Tile” Hexagon Lattice Cassette (HNL)
- Cassette frame: 260 × 200 × 60 mm
- Internals: hex tiles on backplane
- Service: removable tile tray
- Connector: blind-mate backplane
6.2 Backplane & buses (mechanical implications)
- High-speed fabric bus uses a fixed backplane PCB with stiffeners.
- Separate physical channels:
- Data fabric (shielded)
- Power (busbars)
- Safety/control (separate small connector; cannot be disabled by compute module)
6.3 Physical segregation
Within compute bay, create a locked micro-enclosure for:
- SEC (root of trust)
- GOV/SAFE gate
This enclosure is mechanically separate and has no user-serviceable access without special tooling.
7) Power Architecture (Mechanical CAD Impacts)
7.1 Battery pack standard (B-Pack)
- Pack geometry: 300 × 180 × 120 mm
- Weight: 8–14 kg depending chemistry
- Mount: shock-isolated sled + quick disconnect
- Venting path: dedicated downward duct (no shared compute vent)
Option: dual smaller packs for redundancy (ZT-7/10)
7.2 Busbars and routing
- Main DC bus: copper/aluminum busbars inside pelvis ring.
- High-current runs to legs/arms through protected conduits.
Rule: power conduits never share the same channel as high-speed data.
8) Actuation & Joint Cartridge Standard
Define Actuator Cartridge Units (ACU) for hips, knees, ankles, shoulders, elbows.
8.1 ACU module spec (example)
- Envelope: 120 × 90 × 70 mm (joint dependent)
- Mount: 3-bolt triangular pattern + anti-rotation key
- Service: removable without disassembling adjacent limb structure
- Integrated:
- motor/drive OR EAP driver pack
- joint encoder
- thermal sensor
- health microcontroller (optional)
8.2 Structural bones
- Upper/lower limbs are hollow composite shells with internal rails for cable/thermal channels.
- Standard cross-section ensures interchangeability.
9) Synthetic Skin System (Panels + Tactile Mesh)
9.1 Skin panel architecture
- External skin uses standardized removable panels:
- Torso: 6 panels
- Arms: 6 panels/arm
- Legs: 6 panels/leg
- Head: 4 panels
- Panels mount to hidden snap + 2 security screws.
9.2 Two appearance modes
- Human-analog: matte polymer + microtexture + thermal compliance layer.
- Transparent / artificial: translucent polycarbonate/PU blend, visible light channels.
9.3 Tactile mesh routing
- Skin sensor harness connects to Skin Hub in collar bay.
- Quick-disconnect flex connectors at each limb root.
10) Sensor Mast & Head CAD
10.1 Head module “H-Cap”
- Envelope: 210 × 180 × 190 mm
- Mount: 4-bolt to neck ring
- Internal rails for:
- camera block
- depth/IR optional
- microphone array
- cooling micro-duct
10.2 Neck ring
- Contains:
- slip ring (optional)
- data/power junction
- IMU secondary mount
11) Thermal Architecture Specification
Two options; CAD must support both:
Option A — Air Ducting (baseline)
- Spine trunk duct (rear)
- Intake: under rib cage side inlets (filters)
- Exhaust: upper back vents (angled to avoid recirculation)
- Compute bay heat sink + heat pipes to duct
Option B — Liquid Loop (ZT-7/10)
- Pump + micro-radiator in thermal bay
- Quick disconnects at:
- compute bay cold plate
- hip joints (high load)
- shoulder joints
Rule: thermal lines must be serviceable without removing compute modules.
12) Harnessing & Connector Standardization
12.1 Harness corridors
- Dedicated corridors:
- Data corridor (left side spine)
- Power corridor (right side pelvis)
- Safety/control corridor (internal protected channel)
12.2 Connector classes
- Class D: data fabric blind-mate
- Class P: power quick disconnect
- Class S: safety/control (locked, keyed, tamper-evident)
13) Serviceability, Assembly, and Manufacturing
13.1 Assembly sequence (top-level)
- Build spine + pelvis ring subassembly
- Install power bay (PMU/BMS/busbars)
- Install compute bay frame + backplane
- Install thermal bay trunk
- Install limb skeletons
- Install ACU cartridges
- Install harnesses + diagnostic bay
- Install sensor mast + head module
- Install skin panels + tactile mesh
- End-of-line calibration + acceptance tests
13.2 DFM rules
- Reduce unique fasteners (≤ 12 fastener types).
- Use captive screws for service panels.
- Use keyed connectors to prevent mis-mating.
- Avoid hidden fasteners requiring deep disassembly.
14) Documentation Outputs Required from CAD Team
Minimum CAD package:
- Master Assembly (full system)
- Top-level subassemblies:
- Spine + rings
- Compute bay
- Power bay
- Thermal bay
- Each limb (arm/leg)
- Head module
- Skin panel set
- Interface control drawings (ICDs) for every bay and module
- BOM with variant tables (ZT-1/3/7/10)
- Tolerance stack-up report for joints + bay alignment
- Cable & thermal routing drawings
- Service manual exploded views
15) Acceptance Criteria (CAD Freeze Gate)
A “CAD Freeze” is allowed only when:
- All hard points validated against load cases (FEA summary)
- Compute bay cartridges fit with tool access clearance
- Battery removal possible in < 3 minutes (service target)
- At least one limb actuator cartridge removable without full limb disassembly
- Thermal path meets notional envelopes in simulation
- Harness corridors pass bend radius + EMI separation rules
16) Comparative Positioning (Why This Spec Matters)
Without a fixed archetype, R&D diverges and integration becomes sequential and expensive.
With ZT-ICAS:
- multiple teams can design modules in parallel
- suppliers can quote standardized parts
- variants can be produced with predictable amortization
- the series evolves toward ZT-10 with controlled complexity
This is the Model-T production logic applied to AIAndroid architecture.
