AW: [Paparazzi-devel] Re: Paparazzi-devel Digest, Vol 43, Issue 5

[Ethan Arnold]

Hehehe, good answer Anton :-)
Yes, sometimes the simplest solutions are the best...
 
Ethan

________________________________

Von: address@hidden
[mailto:address@hidden Im Auftrag von
address@hidden
Gesendet: Freitag, 12. Oktober 2007 15:29
An: address@hidden
Betreff: RE: [Paparazzi-devel] Re: Paparazzi-devel Digest, Vol 43, Issue 5


David,
In short, no this sensor is not all you need.  The reason for this is that
it is an inertial based sensor.  It will output both rates and
accelerations, but give you no information on attitude.  Without attitude
the aircraft wont know which way is up as we like to say.  People who use
these sensors apply various filters, the most common of which is a kalman
filter to take the data from these noisy and drifting sensors, and try to
get an accurate attitude model.  They are prone to getting confused simply
because the new position is always based on the previous one, so care must
be taken when writing the filter, and to put limits and bounds on the inputs
from the sensors.  
 
In the case of hte IR, although "Crude" as you say, they output an angle.
This absolute attitude means the plane can not get confused of 1 blip of
data is bad, because it will just use the next.  These sensors have proved
they work over water, in deep cold, and even in snow I think(iceland team
chime in here).  So although crude, the proof is in the demonstration
success.  Look at the record of MAV competitions the last 3 years and you
will see its a IR based airplane on top almost every time.  Not bad for some
FMA hobby crap huh?
 
Anton


        -------- Original Message --------
        From: "David Conger" <address@hidden>
        Date: Thu, October 11, 2007 11:25 pm
        To: address@hidden
        
        Greetings again,
        
        I realize even after building the tiny to "fly" the plane I will
need some way for the autopilot to know the attitude and pitch/yaw/roll that
is going on and correct...IR sensors to me seem super crude. 
        
        Has anyone seen these:
http://www.analog.com/UploadedFiles/Data_Sheets/ADIS16350_16355.pdf
        
        Seems to have everything necessary in one place. Would this work
with a Tiny? Anyone willing to hint me to the right resource to learn how I
would do that? I'm assuming tiny would just need to "read" the outputs from
this and simply apply the same PID logic correct? 
        
        I'm guessing in short time these parts will come down in price
considerably. 
        
        Also, I have been lucky. Someone I work with has offered to build me
2 Tiny's. I work for a large company that has labs with all the equipment.
So, he's an awesome resource for me. Seems he found several issues with
either the Mouser Parts and the Circuit Board I'll share when he debriefs me
on completion of the first board. I also hear there is a company nearby that
will build/fabricate circuit boards for me from designs. I will ask him
about the tiny 2.1. So, a big leap forward on my end. Is the Eagletree
design ready for fabrication that's in CVS?
        
        Best Regards,
        David Conger
        
        
        
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