High precision altimeter

Discussions and questions about the Crazyflie Nano Quadcopter
Post Reply
gruffman
Beginner
Posts: 6
Joined: Tue May 28, 2013 8:30 pm

High precision altimeter

Post by gruffman »

Hi, what are or could the high altimeter sensor be used for? (height hovering)?

The resolution is at 10cm but what are the accuracy? +-1.5mBar, what is that in height from zero calibration?

MS5611-01BA03

Kind regards
tobias
Bitcraze
Posts: 2339
Joined: Mon Jan 28, 2013 7:17 pm
Location: Sweden

Re: High precision altimeter

Post by tobias »

There are some ongoing development of a hover mode which should be achievable.
gruffman
Beginner
Posts: 6
Joined: Tue May 28, 2013 8:30 pm

Re: High precision altimeter

Post by gruffman »

and what about the accuracy? I got it to be +-10 meter's ? That have to be wrong.
BillyBag2
Member
Posts: 45
Joined: Wed Jul 10, 2013 8:54 am

Re: High precision altimeter

Post by BillyBag2 »

I think accuracy is not that relevant to the flie. The barometer is designed to be used for measuring heights. You need to calibrate it for absolute height because of the weather. However, assuming stable weather, it could then go on to be used to measure the height of a mountain that you walk/drive/fly up.

The usage in the flie is probably very different.You turn it on, take a reading, count that as zero and fly from there. You can make a simple assumption that you are fling at sea level and use a simple calculation for mb to meters. (I think I used 7mb = 100m)

When flying you just want to go up a bit or down a bit. Resolution is important but absolute accuracy or even scale accuracy is not that important.

Having said all that a few things do not seem to add up. I think the calculation given on the data sheet is in 0.01 mb resolution. Which I think is more like 14cm than 10.
I may have this wrong.

Also, in practice, as you can see from the data sheet, there are many sources of error. In practice it seams only possible to get a good reading by filtering, which will introduce a lag that then upsets the control system.
Post Reply