Skip to content

PR/FAQ: Nav-Trust C2

Mock press release for a simulation prototype, dated at the planned end of the project; nothing in it was released and no company or customer is involved. Every figure is from this repository's measurements and says "in simulation".


6 December 2026 (planned). A new open-source prototype, Nav-Trust C2, gives the operator of a small team of survey drones something they usually do not have: a plain answer to "can I trust this vehicle's position right now?". It was built and tested entirely in simulation.

When satellite navigation degrades, a drone's own estimator can keep reporting a position with unwarranted confidence, and the operator reacts late or not at all. Nav-Trust C2 watches each vehicle's navigation, marks it GREEN, AMBER or RED with a reason in plain language, shows how far the position can be off, and recommends what to do. It never acts on its own: every command waits for the operator's approval and is written to an audit log.

In simulation, it raised an alert a median of 1.2 seconds after satellite navigation was switched off, with no false alerts in nine fault-free runs. For one dangerous failure, a receiver that keeps reporting a good fix while its position freezes, the vehicle accelerates away and no failsafe fires. Nav-Trust C2 flagged it within 3 to 4.5 seconds, while the vehicle was still within a few metres of where it believed it was, and recommended landing it, the only action that stopped the vehicle safely in the tests.

"I honstely could not believe the results..."

The position it displays is not the estimator's own figure, which was wrong far more often than it claimed. It is a bound measured against the simulator's ground truth: within 3 metres in 99% of reports, checked on a separate set of runs.

Nav-Trust C2 is an MIT-licensed prototype for PX4 in Gazebo. make demo runs the console without a simulator, on recorded data, and labels it as a replay.


FAQ

Who is it for? An operator supervising three to five small survey drones, a commander who wants the fleet picture, and an engineer who needs to reproduce incidents. These are hypotheses; no operator has been interviewed yet.

Does it fly the drones? No. The drones fly their missions and run their own failsafes. The console recommends; the operator approves; only then does a command go out. A test enforces that nothing else in the backend can send one.

How does it decide a position cannot be trusted? Two independent checks. One watches whether GNSS is present, degraded, lost or silent. The other watches whether the data that is arriving agrees with the vehicle's own sensors. A receiver that reports a good fix but a frozen position is caught by the second, not the first.

What does "within 3 metres, 99%" mean? In 9,348 simulated reports with the vehicle marked GREEN, the true error was within 3 metres in 99.8% of them (100.0% on the development set, 99.72% on the held-out set). It holds for this simulator, this vehicle and 5 to 12 m/s. It says nothing else.

What if the operator does not answer? The recommendation expires after 60 seconds and is raised again while the vehicle is still RED. The vehicle's own failsafes act regardless.

Why recommend landing, not returning home? Because it was tested. With a frozen position the vehicle does not know where it is, so return-to-launch and hold ended in fast, uncontrolled descents hundreds of metres off; landing stopped it. One run per action, so this shows what is possible, not how often.

What did you test, and what did you not? 32 simulated runs across five kinds of scenario (one without a fault): 14 recorded after the engine was built, and 18 in a held-out set with different speeds and zones. Not tested: real receivers, real interference, other vehicles, link loss, an operator under stress. One held-out expectation was missed: a 6-second stall of the whole simulation produced one false alert, and the report says so.

Is it safe for real use? No. It is a simulation prototype with no authentication, a simulator's failure model and a handful of runs per scenario. The scope is search-and-rescue and area survey; it has no weapons, targeting or effector logic and is not designed for any.

What would you do next? Measure mission completion with a real operator in the loop (the fleet measurement uses a scripted one); try more loss patterns than one lost vehicle; run it with real operators; add link loss; test against real receivers.

How was it built? docs/how-this-was-built.md.