2. Objectives

• Define modular schema components reusable across datasets.
• Support both real-world and simulated sources transparently.
• Add analytical structures (derived metrics, context, labels).
• Enable validation, provenance tracking, and data confidence.
• Maintain full backward compatibility with v0.1.

3. Summary of Key Axes

4. Detailed Axes

🧩 Axis 1 – Modularization & Profiles

• Introduce $defs for core reusable objects (Position, Motion, IMU, Engine, Context, Source).
• Add a top-level field profile: "core" | "fleet" | "simulated" | "contextual".
• Add explicit schema versioning:

  "schema_version": "0.2.0",
  "schema_ref": "https://github.com/telemachus3/telemachus-spec/schemas/telemachus-core-0.2.json"

• Goal: Allow validators to accept subsets of data depending on the profile.

⏱️ Axis 2 – Time & Frequency

Axis 2 focuses on precise temporal alignment and frequency support for high-rate telemetry.
Key goals:

• Support high-frequency timestamps (sub-ms, ns precision).
• Allow flexible sampling rates (Hz, event-based, asynchronous).
• Synchronize multiple sensor streams (GNSS, IMU, CAN, etc.).

Example:

"timestamp": "2025-10-10T14:23:01.123456Z",
"timestamp_ns": 1696947781123456789,
"sampling_rate_hz": 100,
"sync_group": "imu_gnss"

Explanation:
This enables robust time alignment and resampling for analytics and sensor fusion.

🚗 Axis 3 – Vehicle & Powertrain

Axis 3 extends the schema to support a wide range of vehicle types, including internal combustion, electric, and hybrid powertrains.

Example:

"powertrain": {
  "engine": {
    "rpm": 2500,
    "load_pct": 70
  },
  "ev": {
    "soc_pct": 82.5,
    "battery_temp_c": 32.1,
    "power_kw": 45.2,
    "regen_kw": -5.7
  },
  "hybrid_mode": "charge-sustain"
}

Explanation:
This unified block supports data from ICE, EV, and hybrid vehicles under a single schema, facilitating cross-fleet analyses.

🛣️ Axis 4 – Trajectory & Geometry

• Add a new trajectory block:

"trajectory": {
  "curvature_radm": "number",
  "radius_m": "number",
  "road_class": "string",
  "segment_id": "string",
  "distance_m": "number",
  "lane_count": "integer"
}

• Aligns with Road Genome research and curvature datasets.

🌍 Axis 5 – Context Enrichment

• Evolve context → enrichments:

"enrichments": {
  "weather": { "temp_c": "number", "precip_mm": "number", "wind_speed_ms": "number", "visibility_km": "number" },
  "road": { "surface_type": "string", "friction_coeff": "number", "speed_limit_kph": "number" },
  "environment": { "altitude_source": "string", "urban_class": "string" },
  "confidence": "number"
}

• Adds richer environmental and operational context.

🔗 Axis 6 – Provenance & Confidence

• Rename source → provenance:

"provenance": {
  "provider": "string",
  "device_id": "string",
  "firmware": "string",
  "sampling_strategy": "string",
  "confidence": "number",
  "fusion_level": "string"
}

• Supports multi-source fusion and transparent traceability.

🧠 Axis 7 – Derived & Labels

• Add analytical extensions:

"derived": {
  "jerk_ms3": "number",
  "yaw_rate_rads": "number",
  "curvature_rate": "number"
},
"labels": {
  "road_type": "string",
  "driver_behavior": "string",
  "event_type": "string"
}

• Used for machine learning, segmentation, or simulation validation.

🧪 Axis 8 – Simulation Metadata

• Optional block for synthetic datasets:

"simulator": {
  "name": "RS3",
  "version": "3.2",
  "seed": 1234,
  "noise_model": "gaussian",
  "generator": "core2-altitude"
}

• Allows transparent distinction between real and synthetic datasets.

🔒 Axis 9 – Validation & Privacy

• Add validation_flags: boolean checks (gps_fix_ok, imu_dropout, odometer_valid).
• Add privacy block for anonymization metadata (vehicle_id_hashed, geo_masked).
• Require a license field (CC-BY-4.0, ODbL, etc.) for open datasets.

🌐 Axis 10 – Interoperability & Manifest

Introduce a companion manifest.json:

{
  "schema_version": "0.2.0",
  "profiles": ["core", "contextual"],
  "sampling_rate_hz": 10,
  "spatial_coverage": "France metropolitan",
  "temporal_coverage": "2024-01-01/2024-12-31",
  "sources": ["RS3", "Geotab"],
  "license": "CC-BY-4.0"
}

Explanation:
Includes dataset-level metadata and prepares for interoperability with:

• OGC SensorThings API
• OpenTelemetry
• ISO 39030 Vehicle Data Standard

5. Expected Impact

• Backward compatible with v0.1
• Enables lightweight and rich profiles
• Standardizes provenance and quality reporting
• Facilitates integration between simulated and real datasets
• Paves the way for public Telemachus Datasets v2.0

6. Next Steps

1. Implement schemas/telemachus-core-0.2-draft.json
2. Add example datasets in examples/core-v0.2/
3. Open discussion under RFCs category for feedback
4. Collect feedback → refine → tag v0.2-beta
5. Update documentation and validation tools in telemachus-py

7. References

• Telemachus Core v0.1-alpha Schema – September 2025
• RS3 Simulator Documentation – RoadSimulator3 project
• Telemachus Datasets v1.0 – telemachus-datasets
• ISO 39030, OGC SensorThings API, OpenTelemetry Trace Model

End of RFC-0001