How to determine good altitude hold from logfile?

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How to determine good altitude hold from logfile?

Postby HeliHenkie » Fri Feb 08, 2013 4:59 pm

Hi all,

In search of the holy grail of altitude hold I was studying a couple of my logfiles.
Plotting [log_radio_channel5] against [log_gps_height] and [log_ukf_pres_alt].
During altitude hold the graph shows [log_ukf_pres_alt] a relatively level line and [log_gps_height] a slowly descending line.
Physically my quadcopter descends slowly.
If the controller uses [log_ukf_pres_alt] to determine height it doesn't do much, because it's level.

Now I'm wondering, how do I determine good altitude hold from logfile data?
And how does the AQ controller do that?

Best regards,

Jan Willem
HeliHenkie
 
Posts: 93
Joined: Wed Oct 24, 2012 5:33 pm

Re: How to determine good altitude hold from logfile?

Postby JussiH » Sat Feb 23, 2013 8:52 pm

Hi Jan

I have extensively tested the board you sent back, including making flight tests on it.

There is absolutely nothing wrong with it, altitude hold and position hold is working fine.

See below video, flown with your calibration parameters, default values on R65:

https://www.youtube.com/watch?v=b7YBS5l8bYg

That leaves us with the option that something in your setup is wrong. First place to look, is to make sure that your radio is at 700 when the throttle stick is centered. Use the radio tab in QGC to tune, and then set FACTOR_THROTTLE to a value that makes the craft hover at midstick in manual mode. I have a feeling that could be your problem all along.

Otherwise it may be because the altitude controller limit is kicking in and not allowing enough motor output. To tune that, increase NAV_ATL_SPED_IM & NAV_ATL_SPED_OM parameters
JussiH
 
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Joined: Thu Jun 21, 2012 9:25 pm

Re: How to determine good altitude hold from logfile?

Postby JussiH » Sat Feb 23, 2013 8:58 pm

Have you remembered to cover the barometer in foam like described in the wiki?
JussiH
 
Posts: 2103
Joined: Thu Jun 21, 2012 9:25 pm

Re: How to determine good altitude hold from logfile?

Postby HeliHenkie » Sat Feb 23, 2013 9:43 pm

Hi Jussi,

Your movie at YouTube convinces me that there is nothing wrong with the board.
I'd more than settle for that result and I'm convinced somrthing stupid will be the cause of my problems with alt hold.
To get back at your questions.

Yes, I've covered the pressure sensor with foam, so I assume that's not the problem. Or is it possible to put to much foam on the sensor? I've covered the baro sensor with about 3 cm of open cell foam, firmly stuck between the controller board and the gps shield. Is that too much?

Furthermore I'm almost certain my radio outputs around 700 when hovering. This is something I can check in my logfiles.
Can you direct me to the correct parameter name in the logfile so I can exclude simple settings as the cause of my problem?

Best regards,

Jan Willem
HeliHenkie
 
Posts: 93
Joined: Wed Oct 24, 2012 5:33 pm


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