Architecture

Modules

• navfusion.core: canonical state and event types, time/reorder primitives
• navfusion.models: motion and measurement models
• navfusion.filters: filter contracts plus EKF and UKF implementations
• navfusion.engine: orchestration and async event handling
• navfusion.results: run histories and summaries
• navfusion.analysis: consistency metrics (NIS, NEES)
• navfusion.sensors: raw packet to event adapters
• navfusion.viz: plotting helpers

Data path

1. Raw packet -> sensor adapter -> MeasurementEvent
2. Event enters reorder buffer (reorder_window_ns)
3. Events emitted in deterministic timestamp order
4. IMU events drive prediction
5. GNSS events trigger catch-up prediction + update + gating
6. Histories and diagnostics emitted as RunResult

Runtime flow

flowchart LR
    A[Sensor Packets] --> B[SensorAdapter]
    B --> C[MeasurementEvent]
    C --> D[EventReorderBuffer]
    D --> E[FusionEngine]
    E --> F[Predict IMU]
    E --> G[Update GNSS]
    G --> H[Innovation Gating]
    F --> I[ErrorStateEKF]
    H --> I
    I --> J[RunResult]
    J --> K[Consistency Reports and Plots]

State

Nominal state:

• Position (3)
• Velocity (3)
• Attitude quaternion (4)
• Gyro bias (3)
• Accel bias (3)

Error covariance state (15):

• dp, dv, dtheta, dbg, dba