APM Aerial Tracker improvement

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Firstly I must say that this bit of software is outstanding, you are working 
really hard to provide a brilliant bit of kit, well done.

Now the issue, I was setting up an aerial tracker and my fiend has used a Hitec 
winch servo http://www.cornwallmodelboats.co.uk/acatalog/hitec_hs785.html. 
Unfortunately this one rotates 1260 degrees over 1000 pwm, not 360 like the GWS 
in your set up guide. I have tried all combinations that I can with just one 
pwm field and although can get it to sort of work, it is way too sensitive. Its 
range for 360 degrees is 1400 to 1780 pwm. I have tried putting in 140, 380, 
500, 1000 etc in the pwm field but that just causes the servo to either rotate 
without stopping if it is lower than 400 (the figure that causes this) or be 
too sensitive.

It would be helpful if a range could be entered instead of just one value, i.e. 
min pwm and max pwm (it could work out the neutral from that), then any servo 
could be used, not just a GWS as used in the setup details.

Original issue reported on code.google.com by QandG...@gmail.com on 25 Sep 2012 at 9:19

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if your using the maestro, the pwm field doesnt actualy do anything. its all in 
the maestro setup.

Original comment by Meee...@gmail.com on 25 Sep 2012 at 10:18

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in maestro set the range as 380 / 2 = 190
neutral as 1590
min and max as you said.
and that should take care of it.

Original comment by Meee...@gmail.com on 25 Sep 2012 at 10:19

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Original comment by Meee...@gmail.com on 25 Sep 2012 at 10:21

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Yes I we are using a maestro, I will try that as it is slightly different to 
what we have setup already.

Original comment by QandG...@gmail.com on 25 Sep 2012 at 10:24

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let me know how you go.

Original comment by Meee...@gmail.com on 27 Sep 2012 at 12:37

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Tried it today, not quite there, starts to track, then loses it and wanders 
away,eventually comes back close to target. I'll try tweaking it a bit more 
over the next week when the weather improves.

The 3DR trim function, does that only work with the 3DR radio or does it work 
with any radio? We are using an xbee 2.4GHz on one drone and an XRF 
http://shop.ciseco.co.uk/xrf-wireless-rf-radio-uart-rs232-serial-data-module-xbe
e-shape-arduino-pic-etc/ would the auto trim work with those?

Original comment by QandG...@gmail.com on 28 Sep 2012 at 6:12

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Tried lots more times, once I worked out that the aerial needs to face North it 
improved. I was using the trim, but didn't realise the it was based around 
North.

Sort of works, just overturns now, not sure the best way to deal with that, 
maybe reduce the min max settings as the 8 bit is at the the minimum 156? Tried 
190 was too sensitive, so slowly reduced it.

Original comment by QandG...@gmail.com on 10 Oct 2012 at 12:14

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if you are using the trim, make sure the plane is 20m+ away from you. otherwise 
the calculation isnt updated

Original comment by Meee...@gmail.com on 10 Oct 2012 at 12:16

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Hmm, that may explain it. We have the tracker on our vehicle roof and usually 
the drone is armed quite close by, at least a few metres. I'll test it again.

Original comment by QandG...@gmail.com on 10 Oct 2012 at 12:26

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ie detailed version.
if the plane is within 20 m and not been outside of that 20 m the tracker will 
point north. as the angle to the plane is still 0. ie north.
once the plane is outside of the 20 m radius the tracker should turn to that 
angle. and the trim value should be adjusted then. This was to prevent ranndom 
360 degree spins if the plane was close the ot tracker location.

Original comment by Meee...@gmail.com on 11 Oct 2012 at 2:28

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Yes that makes sense, thanks for the more detailed answer. Is that on the wiki, 
it would help others. 

Original comment by QandG...@gmail.com on 11 Oct 2012 at 7:13