Discover · Technology

Three instruments, three answers, and a filter that has to pick one before the next control cycle.

Format
Explainer
Published
30 January 2026
Read
7 min

Demo story Written as an example of the format. Real stories will be edited and fact-checked before publication.

Every sensor is wrong

Inertial units drift. Satellite navigation is precise but can drop out. Air data is direct but responds to weather and blockage. None of them is trustworthy alone, and the vehicle needs one number.

Fusing them

An estimator holds a model of the vehicle’s state and how confident it is in each part of it. Measurements update that estimate in proportion to how much they are trusted. The result is usually better than any single input.

When it goes wrong

Several accidents have come from a single faulty input being trusted too much. Modern designs vote across redundant sensors and are built to discard an outlier rather than follow it.

More on technology