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By mechnerd
#104326
Does anyone know the best way to measure velocity? I am working on a device that measures velocity of a moving vehicle over a rough hilly curvy terrain. The vehicle doesn't have any wheels or axles so I can't use an encoder.

It needs to be pretty accurate and there are serious turns and rapid changes of altitude.

I was thinking gyros and accels...thoughts?
By esklar81
#104328
mechnerd,
It sounds to me that you're on the right track. A couple of things for you to consider:
1) If your precision and update needs are low enough, GPS can be used for velocity.
2) There are lots of folks working with UAVs and lots of products for that market. Have you considered, for example, ArduPilot or ArduPilot Mega? If nothing else, I suggest you read the documentation and commentary for them.

Have Fun,
Eric
User avatar
By phalanx
#104344
May I ask what kind of vehicle has no axles or wheels but is capable of navigating hilly terrain?

Serious question... I'm just curious because nothing is coming to mind.

-Bill
By mechnerd
#104366
Haha. Maybe I'll just letting the guessing continue! Kind fun.

Actually, it's a product I'm developing for the boardsports industry.

I like the auggested boards. I'm a mechanical engineer by trade so I've got a little learning curve!
By NleahciM
#104391
GPS is by far the best solution, IMHO. You're going to have significant drift in your velocity signal if you're using accelerometers.
By meexmachina
#104412
Hey there,

If I would need an accurate measurement, I would most probably invest in a good accurate GPS receiver and an accelerometer. To avoid velocity drift, synchronize yourself every so much time to the GPS signal. The problem is that the accurate GPS receivers have 1 measures per second. The others have 10 Hz or so... I would take a high rate GPS and average velocity every half second. then synchronize the accel. calculations to it...

David
By mechnerd
#104421
Thanks for the suggestions.

David -

Will I have GPS signal issues in mountainous and off the beaten path areas?
Does GPS require a subscription by the user?

Thanks!
By skimask
#104431
phalanx wrote:May I ask what kind of vehicle has no axles or wheels but is capable of navigating hilly terrain?
Serious question... I'm just curious because nothing is coming to mind.
-Bill
The Human Vehicle! :)