Provisional prototype architecture for S1 printed dummy models.
This document defines the mechanical and software boundary between an ATOS sled and interchangeable mission modules. It is not a release-to-manufacture specification and does not certify structural, passenger, battery, electrical, or maglev hardware.
The S1 sled is a reusable mobility platform. It owns movement, coupling, identity, sensing, and the standardized mechanical interface. A mission module owns the passenger, cargo, energy, service, or experiment function installed on top of the sled.
Keeping the sled identity separate from module identity lets ATOS:
- swap modules without losing permanent sled health history;
- form software-defined consists from physical sleds;
- admit or reject routes based on the composed sled/module envelope;
- test center of mass, ballast, and route clearance before hardware is finalized;
- evolve modules without redefining the sled movement interface.
The current printable prototype uses configurable defaults:
| Parameter | Default |
|---|---|
| Length over coupler faces | 320 mm |
| Structural deck length | 280 mm |
| Overall width | 72 mm |
| Deck height above guideway datum | 30 mm |
| Module footprint | 240 x 64 mm |
| Module attachment stations | 4 |
| Prototype target module mass | up to 1.5 kg |
These values are starting points for printed fit and loading experiments. Measured replacements belong in the versioned CAD parameters, manifests, and docs/engineering/s1-vehicle-dynamics-loading-envelope.md.
S1 uses the coordinate system from the loading-envelope document:
- X longitudinal, positive toward the declared front;
- Y lateral, positive left when facing forward;
- Z vertical, positive upward.
The important datums are:
| Datum | Meaning |
|---|---|
| G0 | Guideway reference plane |
| D0 | Top of structural sled deck |
| C0 | Coupler pivot datum |
| M0 | Module interface datum |
| X0 | Longitudinal center plane |
| Y0 | Lateral center plane |
All printed reference parts should carry visible datum marks so physical measurements can be tied back to the software manifests.
An S1 sled owns:
- permanent sled identity and maintenance state;
- guideway interface, support or levitation nodes, and local movement enforcement;
- coupler pivots, drawbar interfaces, articulation sensors when fitted, and safe uncoupling features;
- module presence and attachment state;
- low-level power/data negotiation with the tile fabric and module;
- measured mass-property observations when available;
- route-admission state for the composed sled/module vehicle.
The sled must not assume that one module class maps to one route class. Route admission is based on the composed manifest and current measurements.
A mission module owns:
- module identity and type;
- tare mass and declared center of mass;
- payload capacity, payload shift risk, and envelope class;
- passenger, cargo, energy, service, or experiment capabilities;
- module-side attachment features;
- power and thermal requirements;
- route restrictions that are stricter than the sled baseline.
The module does not own sled movement authority. It contributes constraints that the sled, dispatch planner, and route checker must honor.
The S1 prototype keeps a four-point module interface unless a later reviewed engineering change replaces it. The four attachment stations provide:
- repeatable X/Y module location;
- anti-lift retention;
- anti-shear load paths for dummy testing;
- visible inspection access;
- clear separation between structural retention and any electrical connector.
The electrical connector must not be used as the primary alignment or retention feature.
S1 sleds can operate alone or as members of software-defined consists. Coupling is a mechanical constraint and a software relationship:
- the physical coupler defines yaw range, vertical play, drawbar length, and draft/compression limits;
- ATOS represents the consist as a temporary coalition of permanent sled identities;
- route admission checks the aggregate consist geometry and each local coupler angle;
- split, merge, and reorder operations are explicit transactions.
For the printed prototype, couplers are replaceable dummy parts used for low-speed geometry and articulation tests only.
The printable kit shall support controlled mass-property testing:
- ballast pockets in all four quadrants;
- a longitudinal ballast channel;
- an optional elevated ballast mount;
- module and sled CG marker locations;
- four support/load-cell fixture geometry;
- repeatable removable ballast for open-bin and asymmetric-load experiments.
Ballast features are test instrumentation, not production packaging.
Before a composed S1 vehicle enters a route, software checks should include:
- sled and module identity;
- interface-version compatibility;
- attachment state at every required station;
- total mass;
- CG X/Y/Z;
- support-node loads and imbalance;
- static envelope and swept envelope;
- minimum curve radius;
- coupler articulation;
- acceleration, braking, and jerk limits;
- power and thermal needs;
- platform and station clearance;
- payload-shift risk;
- degraded support, coupler, sensor, or power state.
The machine-readable manifests under schema/examples/ are examples of this admission contract.
Issue #17 creates the first S1 printable prototype kit:
- parametric OpenSCAD in
cad/s1/; - generated STL assets in
cad/s1/stl/; - printable fixtures for CG, articulation, and clearance testing;
- machine-readable manifests in
schema/examples/; - validation tooling in
tools/cad/; - the provisional loading envelope in
docs/engineering/.
All outputs remain prototype evidence until measured physical test results replace assumptions through reviewed revisions.