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Comment by appletrotter | Hacker News Reader

> You cannot achieve g-forces dancing anywhere close to a serious crash.

did you just make up that fact?

https://www.bernards.cz/news/irish-dancers-get-pilot-g-force...

“pilot g-force” is nothing compared to a crash. Pilots get up 9G sustained because that’s when people start passing out.

A 30mph car crash into a solid obstacle spikes at 30G https://www.jrlawfirm.com/blog/auto-accidents/car-accident-g...

Race car drivers have walked away from g-force as high as 78G https://www.essentiallysports.com/f1-news-from-max-verstappe...

We’re talking an order of magnitude here. Algorithms should be able to tell the difference.

It's worth noting that a phone bouncing around in a pocket can experience substantially more acceleration than the person carrying it.

I had one of these alerts go off once from my watch. After a really hard fall from tripping during a trail run. I still have the scars.

The alert said: “You had a hard fall and stopped moving. Press this button or we call help”

The “stopped moving” part seems like the perfect proxy here. People in a car crash experience a huge spike in G-force once. Then it stops. Or maybe it goes for a few seconds if you’re rolling down the highway.

Car crashes don’t go on for minutes upon minutes. This seems like something a machine learning algorithm could handle. At the cost of calling 911 3min after a crash instead of 3sec. That’s still much faster than how long it takes people to call for help.

Should this not have been accounted for when designing the feature?

Yes, but it explains why the problem is not as easy as the g-force comparison makes it sound.

how much more?

are we sure it's enough to excuse the failed crash detection described in the article (IE do we know the bouncing around generates multiple tens of Gs like an accident)?

without such a confirmation, the error is still inexcused

with it, the error seems like the feature is just poorly implemented or perhaps even poorly thought out

4.5g exceeds the threshold for a mild accident. A person, especially depending on any pre-existing conditions, can be injured with this much force.

https://www.researchgate.net/figure/Thresholds-g-forces-for-...

I believe 4.5gs would be like a 9-10mph crash.

What percentage of 9-10mph crashes do you think result in any emergency services being called? I would hazard a guess that it's less than 50% including a non-emergency call to police and less than 10% for EMS. It absolutely does not warrant an automatic call to 911.

I believe you are mistaking crashing a car with driving a car.

There are wildly different G-forces involved.

Not confused, here's a table which breaks things down a little:

https://www.researchgate.net/figure/Thresholds-g-forces-for-...

My assumption is that they want to trigger the alarm even for mild accidents.

Note that the Gs experienced by the dancers in my previously shared article approach the threshold for a mild accident. I wonder how they conducted the experiment, and if a phone held in a person's hand while they are dancing might experience even more Gs than the person's body.

edit: I think 4.5gs is equal to a 9-10mph crash.

4.5G is nothing.

"A concussion occurs at roughly 90 to 100 g-force, which equates to smashing your skull against a wall at 20 mph" - https://news.umich.edu/football-helmet-sensors-help-research...

These comments are making it quite clear why stuff like this makes it to production.

4.5G is a mild accident. You're unlikely to sustain major injury, but it's not nothing.

https://www.researchgate.net/figure/Thresholds-g-forces-for-...

90-100g is a pretty extreme amount of force.

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