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Mobile phone accelerometer apps, do they work at all?


John K

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Chaps,

I'm extremely sceptical about how ( or even if ) any of these smart phone 0 to 60 apps work.

Has anybody tried any and compared them to a proper timing rig?

If they are even close to accurate, I am happy to waste a few pennies on getting one.

BTW would have to be Windows phone compatible, I only have a work phone and they swapped my beloved Nokia 3109 for some Carlos Fandango all singing all dancing Nokia Lumia thing.

Which I can't use...

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Satellites just wouldn't keep up with my car :yellow-westy: , I'd be doing 60 before they realised I moved. :)

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Tried some, The refresh rate of a phones gps is not up to the task.

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Useful for tracking a blat about the hills if that's your bag but not for a single 0-60 shoot out, nowhere near accurate enough.

 

Mountain bikers and runners use them a lot for training and local king-of-the-mountain records are highly prized on a pedal bike, the GPS trackers are pretty iffy at best and regularly get confused with what trail you're riding on at walking pace, let along being accurate enough to time a 0-60 run in a car. 

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I thought they worked off the phones internal accelerometer, rather than a GPS signal?

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It would only be measuring the G force of the car, other new cars have them these days.   It's time over distance that measures the 0-60 and would need satellite tracking for that, besides they are only accurate to 10metres I believe for public consumption.

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It would only be measuring the G force of the car, other new cars have them these days. It's time over distance that measures the 0-60 and would need satellite tracking for that.

If you sampled regularly enough you could use the equations of uniform motion to calculate 0-60 if you know the acceleration rate (i.e 'G force')

http://en.m.wikipedia.org/wiki/Equations_of_motion

ETA: Here you go, second paragraph :)

http://www.bunsentech.com/products/dynolicious/index.php

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The basic problem is the error rate on the accelerometer increases with the square of time, you need an external reference (such as GPS) and some fairly serious maths to keep the errors under control.

 

Upshot I guess is that some app/phone combinations will work much better than others due to sensor differences and how well the app handles the errors for that sensor. 

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I had one but it couldn't keep up with the mighty cross flow powered red and black beast

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If you sampled regularly enough you could use the equations of uniform motion to calculate 0-60 if you know the acceleration rate (i.e 'G force')

http://en.m.wikipedia.org/wiki/Equations_of_motion

ETA: Here you go, second paragraph :)

http://www.bunsentech.com/products/dynolicious/index.php

 

Inertial navigation. Used by people with ICBM's to drop a nuke on a city from half way round the world. As has been mentioned the inaccuracy builds quickly. One of the reasons GPS was invented was to increase the accuracy so you could drop a bomb on some ones front porch from half way round the world.

 

Not tried one of these phone apps, but the accelerometers in phones are used to supplement the GPS for navigation. Especially useful in places like cities where tall buildings can restrict the number of satellites the phone sees. It will help keep you on track till the next decent GPS fix.

 

Jen

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The biggest problem I see is the speed of the built in GPS receivers. The iphone only has a 1hz receiver and allot can happen in a second. You can buy after market Bluetooth ones around 10hz but that just makes it expensive.

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