gps-denied-onboard/_docs/02_document/risk_mitigations.md

Risk Assessment — Architecture Review — Iteration 01

Evaluator Pass Summary

Check	Result	Notes
Single Responsibility	Pass	Components each own one primary concern: ingest, VIO, safety, Satellite Service sync/retrieval, verification, Tile Manager storage/generation, MAVLink, FDR, validation
Dumb Code / Smart Data	Pass	Complex behavior is mostly expressed through DTOs, mode labels, covariance fields, manifests, and gates
Interface Consistency	Pass with fix	Safety wrapper no longer directly depends on Tile Manager for anchor acceptance; cache freshness/provenance travels through AnchorDecision
Circular Dependencies	Pass with caution	Runtime flow is acyclic at component ownership level; MAVLink remains a bidirectional protocol adapter but owns no localization policy
Missing Interactions	Pass	Pre-VIO occlusion, IMU-only blackout, relocalization, tile writes, FDR, and SITL validation are all represented
Security Considerations	Pass	Signed cache sidecars, source/system ID checks, spoofing rejection, and no in-flight satellite-provider or Satellite Service access are covered
Performance Bottlenecks	Pass	Jetson latency, VPR/local matching, FDR append pressure, PostgreSQL availability, and thermal limits are identified
API Contracts	Pass	Core DTO handoffs are documented: FramePacket, VioStatePacket, AnchorDecision, PositionEstimate, FdrEvent

Risk Scoring Matrix

	Low Impact	Medium Impact	High Impact
High Probability	Medium	High	Critical
Medium Probability	Low	Medium	High
Low Probability	Low	Low	Medium

Acceptance Criteria by Risk Level

Level	Action Required
Low	Accepted and monitored
Medium	Mitigation plan required before implementation
High	Mitigation + contingency plan required, reviewed during implementation
Critical	Must be resolved before proceeding to next planning step

Risk Register

ID	Risk	Category	Probability	Impact	Score	Mitigation	Owner	Status
R01	ADTi 20MP 20L V1 public specs conflict with planning assumptions for resolution, FPS, lens, interface, and temperature	Technical / External	Medium	High	High	Pin manufacturer datasheet and exact lens/interface before implementation; make camera calibration/spec task a bootstrap blocker	Camera ingest/calibration	Mitigated by gate
R02	BASALT may underperform or lose tracking on nadir fixed-wing low-parallax terrain	Technical	Medium	High	High	Public replay with MUN-FRL/ALTO/Kagaru/EPFL where applicable, representative target replay, OpenVINS reference comparison, Kimera backup path	BASALT VIO adapter	Mitigated by validation
R03	BASALT confidence/covariance may under-report real error	Safety	Medium	High	High	Wrapper owns covariance calibration; compare against ground truth, satellite residuals, and OpenVINS reference; never emit optimistic horiz_accuracy	Safety/anchor wrapper	Mitigated by wrapper design
R04	Total occlusion detector may false-negative and feed unusable frames into VIO	Safety / Technical	Medium	High	High	Conservative pre-VIO occlusion gate, FDR status, tests for total blackout, and fallback to IMU-only dead_reckoned mode	Camera ingest/calibration	Mitigated by spec/test
R05	IMU-only blackout propagation could be trusted too long	Safety	Medium	High	High	Monotonic covariance growth, dead_reckoned label, fix_type=0/horiz_accuracy=999.0 when >30 s or covariance >500 m	Safety/anchor wrapper	Mitigated by AC gate
R06	DINOv2-VLAD + ALIKED/DISK-LightGlue exceeds Jetson latency/memory budget	Performance	Medium	High	High	Trigger-only execution, CPU FAISS first, top-K caps, model profiling, TensorRT only after fidelity checks	Satellite Service / Anchor verification	Mitigated by profiling gates
R07	PostgreSQL/PostGIS local DB is unavailable or too heavy for onboard runtime	Technical / Operational	Medium	High	High	Run local onboard PostgreSQL, health-check before flight, keep large payloads in files, fail mission cache validation if DB unavailable	Tile Manager / FDR	Mitigated by deployment gates
R08	Generated tile cache poisoning corrupts future anchors	Security / Safety	Low	High	Medium	Sigma gate, provenance sidecars, post-flight Satellite Service voting, no direct promotion to trusted basemap	Tile Manager	Mitigated by policy
R09	Public datasets do not cover final target terrain or commercial license needs	External / Schedule	Medium	Medium	Medium	Use public data for de-risking only; representative synchronized target data remains mandatory for acceptance	Validation harness	Mitigated by acceptance rule
R10	MAVLink GPS_INPUT parameters or Plane behavior differs from assumptions	Integration	Medium	High	High	Plane SITL release gate with production parameters, spoofing/failsafe tests, raw field validation with pymavlink	MAVLink/GCS integration	Mitigated by SITL gate
R11	FDR appends or PostgreSQL indexing interferes with hot-path latency	Performance	Medium	Medium	Medium	Append asynchronously, use CBOR payload segments for high-volume data, keep PostgreSQL as event index/query surface	FDR/observability	Mitigated by design
R12	GPL/non-commercial tooling accidentally enters production or acceptance evidence	Legal / Compliance	Low	High	Medium	Keep OpenVINS/ORB-SLAM3 reference-only; license-tag datasets before CI; SuperPoint only after legal approval	Validation harness / Architecture	Mitigated by gates

Detailed Risk Analysis

R01: Camera Specification Mismatch

Description: Public ADTi pages show 5456 x 3632 stills, 2 fps continuous capture, Sony E mount, and -10..40 C operation. The project needs the exact production lens, camera interface, sustained capture behavior, thermal behavior, and calibration model.

Trigger conditions: Manufacturer documentation or hardware testing contradicts assumed FPS, interface, temperature, or lens characteristics.

Affected components: Camera ingest/calibration, BASALT VIO adapter, validation harness, deployment procedures.

Mitigation strategy:

1. Make camera specification verification a bootstrap task.
2. Require manufacturer datasheet or hardware measurement before implementation claims 3 fps or hot-environment operation.
3. Version calibration data by exact camera/lens/interface.

Contingency plan: Reduce frame rate assumptions, adjust latency tests, or select a different navigation camera/lens/interface.

Residual risk after mitigation: Medium.

Documents updated: glossary.md, architecture.md, components/01_camera_ingest_calibration/description.md, deployment/deployment_procedures.md.

---

R02: BASALT Nadir Fixed-Wing Fit

Description: BASALT is a strong VIO candidate, but fixed downward cameras over planar terrain can cause low-parallax and texture-degeneracy cases.

Trigger conditions: Public or representative replay shows high drift, frequent tracking loss, or poor initialization.

Affected components: BASALT VIO adapter, safety/anchor wrapper, validation harness.

Mitigation strategy:

1. Run MUN-FRL first for synchronized nadir camera + IMU + ground truth.
2. Add ALTO/Kagaru/EPFL slices where available for aerial/fixed-wing realism.
3. Compare against OpenVINS reference and Kimera backup.

Contingency plan: Keep Kimera backup or build a project-owned fallback estimator around OpenCV + IMU only after replay evidence requires it.

Residual risk after mitigation: Medium.

Documents updated: architecture.md, components/02_basalt_vio_adapter/description.md, tests/test-data.md.

---

R03: Covariance Under-Reporting

Description: Incorrect confidence is more dangerous than no estimate because the flight controller may trust a false fix.

Trigger conditions: Replay error exceeds reported covariance, or anchors are accepted despite inconsistent residuals.

Affected components: Safety/anchor wrapper, MAVLink/GCS integration, FDR/observability.

Mitigation strategy:

1. Make wrapper covariance the product authority, not BASALT raw confidence.
2. Validate calibration against ground truth, satellite residuals, and OpenVINS reference.
3. Map horiz_accuracy so it never under-reports the 95% semi-major covariance axis.

Contingency plan: Degrade to no-fix sooner and require operator relocalization or mission abort behavior.

Residual risk after mitigation: Medium.

Documents updated: architecture.md, components/03_safety_anchor_wrapper/description.md, tests/blackbox-tests.md.

---

R04: Total Occlusion Detection Failure

Description: If total occlusion is not detected before VIO, BASALT may receive unusable frames and produce misleading state updates.

Trigger conditions: Lens cover, cloud/whiteout, decode failure, underexposure/overexposure, or textureless frame reaches VIO as usable.

Affected components: Camera ingest/calibration, safety/anchor wrapper, BASALT VIO adapter.

Mitigation strategy:

1. Camera ingest exposes OcclusionReport and sets usable_for_vio=false for total occlusion/blackout.
2. Total occlusion bypasses BASALT for that frame.
3. Safety wrapper switches to IMU-only dead_reckoned propagation with monotonic covariance growth.

Contingency plan: Tune detector conservatively and accept temporary false-positive IMU-only degradation over false VIO confidence.

Residual risk after mitigation: Medium.

Documents updated: components/01_camera_ingest_calibration/description.md, components/03_safety_anchor_wrapper/description.md, system-flows.md, diagrams/flows/flow_normal_localization.md, tests/resilience-tests.md.

---

R05: IMU-Only Mode Over-Trust

Description: IMU-only propagation drifts quickly and must be treated as an emergency bridge, not a long-duration solution.

Trigger conditions: Blackout lasts longer than 30 seconds or covariance exceeds 500 m.

Affected components: Safety/anchor wrapper, MAVLink/GCS integration, FDR/observability.

Mitigation strategy:

1. Emit source_label=dead_reckoned during IMU-only mode.
2. Grow covariance monotonically.
3. Emit fix_type=0, horiz_accuracy=999.0, and VISUAL_BLACKOUT_FAILSAFE at thresholds.

Contingency plan: Stop publishing valid fixes and require relocalization/operator action.

Residual risk after mitigation: Low.

Documents updated: components/03_safety_anchor_wrapper/description.md, system-flows.md, tests/blackbox-tests.md, tests/resilience-tests.md, tests/traceability-matrix.md.

---

R06: Trigger Path Performance

Description: DINOv2-VLAD and learned local matching can exceed Jetson latency/memory limits.

Trigger conditions: Relocalization exceeds p95 latency, memory budget, or causes thermal throttling.

Affected components: Satellite Service, anchor verification, validation harness.

Mitigation strategy:

1. Keep VPR/local matching trigger-based.
2. Use CPU FAISS first and bounded top-K.
3. Accept optimized engines only after descriptor-fidelity tests pass.

Contingency plan: Reduce descriptor resolution/model size, reduce top-K, or fall back to classical features for emergency operation.

Residual risk after mitigation: Medium.

Documents updated: architecture.md, components/04_satellite_retrieval/description.md, components/05_anchor_verification/description.md, tests/performance-tests.md.

---

R07: Onboard PostgreSQL/PostGIS Availability

Description: PostgreSQL/PostGIS is now the structured metadata store. If local DB availability or resource use is poor, cache/FDR queries may fail.

Trigger conditions: Local DB does not start, DB files corrupt, DB consumes too much memory/I/O, or migrations fail.

Affected components: Tile Manager, FDR/observability, deployment procedures.

Mitigation strategy:

1. Require local onboard PostgreSQL health check before flight.
2. Store large imagery/descriptors/CBOR payloads as files, not DB blobs.
3. Treat DB unavailability as a mission-cache validation blocker.

Contingency plan: Abort mission-cache activation and run only no-cache degraded modes or resync/rebuild DB before flight.

Residual risk after mitigation: Medium.

Documents updated: data_model.md, architecture.md, components/06_cache_tile_lifecycle/description.md, components/08_fdr_observability/description.md, deployment/environment_strategy.md.

---

R08: Cache Poisoning

Description: A bad generated tile could be written back and later used as a trusted anchor.

Trigger conditions: Generated tile is promoted despite high parent covariance, stale source, bad sidecar, or inconsistent overlap voting.

Affected components: Tile Manager, safety/anchor wrapper, Satellite Service integration.

Mitigation strategy:

1. Require tile-write sigma gates.
2. Store generated tiles as candidates with signed sidecars.
3. Promote only through post-flight Satellite Service validation/voting.

Contingency plan: Quarantine generated tiles and invalidate affected cache regions.

Residual risk after mitigation: Low.

Documents updated: architecture.md, components/06_cache_tile_lifecycle/description.md, tests/security-tests.md.

---

R09: Dataset Coverage / Licensing

Description: Public datasets may not match target terrain, may lack raw synchronized IMU, or may have non-commercial restrictions.

Trigger conditions: MUN-FRL/ALTO/Kagaru/EPFL slices are unavailable, unrepresentative, or license-incompatible for acceptance.

Affected components: Validation harness, BASALT VIO adapter, anchor verification.

Mitigation strategy:

1. Use public datasets for de-risking only.
2. License-tag datasets before CI jobs.
3. Require representative synchronized target data for final acceptance.

Contingency plan: Collect a target replay dataset before final acceptance.

Residual risk after mitigation: Medium.

Documents updated: tests/test-data.md, deployment/environment_strategy.md, deployment/ci_cd_pipeline.md.

---

R10: Plane GPS_INPUT Integration

Description: ArduPilot Plane EKF and GPS_INPUT handling may differ from assumptions, especially around accuracy fields, ignore flags, velocity fields, and spoofing transitions.

Trigger conditions: Plane SITL rejects or mishandles emitted GPS_INPUT, or QGC status is insufficient.

Affected components: MAVLink/GCS integration, safety/anchor wrapper, validation harness.

Mitigation strategy:

1. Use pymavlink for exact GPS_INPUT field control.
2. Gate release on Plane SITL with production parameters.
3. Validate spoofing/failsafe and QGC status behavior.

Contingency plan: Adjust parameter guidance/output fields before hardware deployment.

Residual risk after mitigation: Medium.

Documents updated: components/07_mavlink_gcs_integration/description.md, tests/environment.md, deployment/ci_cd_pipeline.md.

Architecture/Component Changes Applied

Risk ID	Document Modified	Change Description
R04	components/01_camera_ingest_calibration/description.md	Added explicit detect_occlusion, OcclusionReport, and pre-VIO bypass behavior
R04/R05	components/03_safety_anchor_wrapper/description.md	Added propagate_imu_only, total_occlusion, monotonic covariance behavior, and no direct Tile Manager dependency
R07	data_model.md	Replaced embedded DB references with PostgreSQL/PostGIS structured metadata and CBOR FDR payload segments
R07	architecture.md	Added PostgreSQL/PostGIS ADR and FDR storage decision
R05	tests/blackbox-tests.md / tests/resilience-tests.md	Made total occlusion and IMU-only blackout behavior explicit

Summary

Total risks identified: 12
Critical: 0 | High: 7 | Medium: 5 | Low: 0
Risks mitigated this iteration: 12
Risks requiring user decision: None immediately. Future decisions are tied to exact camera hardware proof, dataset license approval, and representative data collection timing.