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DeveloperPermalink Reply by Randy on March 27, 2012 at 7:29am

Veikko,

     Well..actually in a number of places in the code we check is the lat is zero..and this is our way of checking if we have a good GPS value.  I don't think it's likely that you'd crash but you might have trouble setting a way point at exactly lattitude zero.  Now, if you live near zero lattitude please give it a try and report back!  :-)

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Permalink Reply by Gábor Zoltán on March 26, 2012 at 7:09am

Ahhhh thank you Randy,

 

A was afraid that my APM might be broken. I was hopeing, that it is some kind of software issue. :)

Thank you for your attention.

 

Gábor 

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Permalink Reply by Veikko Vierola on March 26, 2012 at 7:17am

Randy, could it be possible to change the APM code so that the barometer would be calibrated last in the sequence, for example 45-60 seconds after power up. This way the GPS would have enough time to get satellites and steady position for the initial altimeter calibration?

Or maybe after a reasonable VDOP value is achieved..

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DeveloperPermalink Reply by Randy on March 26, 2012 at 7:32am

I'd guess that's do-able.  What we do on the arducopter side is we redo the barometer calibration when you arm the motors..which is something you normally do just before take-off (and usually something like 30 seconds after power-up).  I guess it's worth having a chat with Doug or Tridge who know a lot more about this kind of thing.  I'll point them towards this chat.

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Permalink Reply by Gustav Kuhn on March 26, 2012 at 7:44am

Thanks Randy,

Fortunately it was too windy to test the new code this weekend :-)

Think the fix will be out before the weekend ?

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DeveloperPermalink Reply by Randy on March 26, 2012 at 7:58am

I would guess that once Chris knows, he'll be keen to push the fix but I can't make any guarantees as it's really up to Tridge, Doug and Chris.  I've sent them an email and I expect it won't be too long.  It'll probably need someone to do a test flight with the latest code though.

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Permalink Reply by Gustav Kuhn on March 26, 2012 at 11:48am

Sorry to be a pest, but can I tell the APM to only, or at least mostly use GPS data for altitude ?

Is this a new bug, if so, what version of the ArduPlane code would not have it ?

Here in Africa it is not uncommon to have daytime shade temps deep in the 30's

Must admit, I haven't seen this bug in any previous flights, using older code, will check later if I still have a copy.

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Permalink Reply by Veikko Vierola on March 26, 2012 at 12:06pm

You can choose how much APM uses baro vs gps (ALT_MIX)

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DeveloperPermalink Reply by Randy on March 26, 2012 at 4:47pm

It is a bug i added and is only in 2.3. Older versions are fine.

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Permalink Reply by Veikko Vierola on March 26, 2012 at 7:49am

Thanks, that would be great :)

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Permalink Reply by Andke on March 26, 2012 at 12:40pm

Randy , could you please comment on how this is possible ?

bad GPS fix, gives me realistic,changing altitude with a huge offset.

http://youtu.be/LhRxeRjXG5Y

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Permalink Reply by Charles Breingan on April 22, 2013 at 11:35am

I'm having the same issue. Before GPS lock, the altitude fluctuates around zero as expected. When the system gets GPS lock, it seems to be a random number between 60 and 500 that is a constant offset in altitude that persists as long as the system is powered. When you restart the ardupilot the number changes, but it is never near correct.

Using a MediaTek GPS with most recent Arduplane on APM 2.5.

Any thoughts on what could cause this?

Thanks.

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