Scenario kind pagesEdit on GitHubSource: docs/kinds/by-kind/gnss-ins.md

gnss-ins (scenario kind)

Scenario kind of the engine v0.38.0, family Inertial, fusion and quantum sensors. Advisory: analysis output from a research and engineering tool, not type-approved navigation equipment and not a safety-of-life service. Every label here is the engine's or the verification matrix's; a kind is MODELLED unless the matrix says otherwise (how a label is earned: the README's Evidence section).

What it does#

Loosely- and tightly-coupled GNSS/INS error-state EKF.

One run of scenarios/gnss-ins.toml summarises as: scenario c55a6246bd6f | gnss-ins | quantum outage-RMS fused 1.9m vs free 130.7m (hold 60s, avail 1.00) | classical fused 3.1m vs free 314.3m (hold 60s, avail 1.00)

Inputs#

From the schema (kshana kinds --json):

  • Required fields: seed, threshold_m, time, gnss, imu_quantum, imu_classical
  • Optional fields: fix_interval_s, sigma_pos_m, sigma_vel_mps, lat_deg, lon_deg, alt_m, trajectory, tight

The example scenarios/gnss-ins.toml sets, among others:

Field Value Unit
alt_m 50 m
fix_interval_s 1 s
gnss.windows[0].state nominal text
gnss.windows[0].t0 0 not stated
gnss.windows[0].t1 100 not stated
gnss.windows[1].state denied text
gnss.windows[1].t0 100 not stated
gnss.windows[1].t1 160 not stated
imu_classical.accel_bias [0.03, -0.02, 0] m/s^2
imu_classical.gyro_bias [0, 0, 1.0000e-4] rad/s
imu_classical.id tactical-imu text
imu_classical.provenance Tactical-grade MEMS/quartz inertial unit: larger residual bi text

Run it#

kshana scenarios/gnss-ins.toml

6 bundled scenarios use this kind; the others are in scenarios/.

What it gives#

The scalar results of that run, with the units the engine states:

Result Value Unit
classical.fom.availability 1 1
classical.fom.drift_slope_m_per_s 0.090464 m/s
classical.fom.holdover_s 60 s
classical.fom.integrity no value not stated
classical.fom.pos_p95_m 5.713763 m
classical.fom.pos_rms_m 3.134426 m
classical.fom.security no value not stated
classical.free_outage_rms_m 314.335637 m
classical.fused_outage_rms_m 3.134426 m
classical.spec.id tactical-imu text
The chart the engine writes for scenarios/gnss-ins.toml, kind gnss-ins

Evidence#

No matrix row names this kind by name; the label on its result is the engine's own, above.

The rows the run itself exercised, with the oracle the matrix gives each (the public sources are named there):

  • MODELLED Cold-atom interferometer accelerometer from first principles (k_eff·T², QPN). Oracle (ExternalDataset): Published CAI primary-paper numeric vectors (Cheinet 2008 transfer function; Peters/Freier sensitivity): k_eff·T² matched exactly, shot-noise ASD a one-sided floor within ~2× of each published instrument (real devices carry technical noise above the quantum floor). A bracket, not parity. 0.30 round 2 (pre-registered fcb9ac64), a finding (stays MODELLED): the QPN-only rotation noise against the measured Gauguet et al.
  • VALIDATED 15-state error-state EKF, loosely coupled (validated on a real IMU/GNSS drive against NaveGo); a tightly coupled pseudorange/Doppler UKF and a coupled clock+pos. Oracle (ExternalDataset): NaveGo v1.4 (R. Gonzalez, LGPL-3.0, run as a tool under GNU Octave, never linked): its loosely coupled ins_gnss on its own real Ekinox IMU/GNSS land-vehicle drive, both solutions scored against the Ekinox reference trajectory. Both filters read the same 20 Hz float32 input, and Kshana's configuration is mapped mechanically from the dataset's published parameters. Kshana's horizontal and vertical position RMS and its
  • MODELLED Deterministic, scenario-hashed, SBOM + cross-platform golden gates. Oracle (ExternalDataset): SBOM conformance to the official CycloneDX 1.5 JSON Schema (+ valid SPDX identifiers) — an external published standard, zero validation errors over the full dependency graph; the FoM-determinism / byte-reproducibility part remains a pinned self-consistency check, so the row stays MODELLED

Limitations#

What the run's own report says is not modelled or not validated:

  • Quantum inertial sensor performance is MODELLED, not validated: a sub-claim is externally checked, but the whole capability composes modelled pieces, so the capability stays Modelled. (verification matrix (docs/MODELLED-RATIONALE.md))
  • Reproducibility & software assurance is MODELLED, not validated: a sub-claim is externally checked, but the whole capability composes modelled pieces, so the capability stays Modelled. (verification matrix (docs/MODELLED-RATIONALE.md))

See also#