speed and alt in Alt/Position hold mode

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speed and alt in Alt/Position hold mode

Postby Ruffio » Wed May 08, 2013 7:07 pm

I try to solve my to problems when flying in Alt/Position hold.
Witch PIDs schould I tune to get:
1. Speed up AQ - for now max speed is much smaller than in manual mode and in mission mode.
2. Descending alt - loos starting alt in horizontal fling. I tuned alt hold, spped in descend andclimb but when copter is moving only verticaly.

I cann't find any post about on these topics, where I can find suitable informations?
Please give me some hints.

ps. of course I read and use information on wiki http://autoquad.org/wiki/wiki/flying/tuning-and-troubleshooting/ and some post about alt tuning with success.
regards,
Rafal
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Re: speed and alt in Alt/Position hold mode

Postby Ruffio » Fri May 10, 2013 12:01 am

I hope to find (in code as Max suggest to looking for) answer for my first question:
"Speed up AQ" - NAV_MAX_SPEED parameter, default 5 m/s, available only in All parameters secion.

2nd question - I dont think I will find answer in code, please help.
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Re: speed and alt in Alt/Position hold mode

Postby Max » Fri May 10, 2013 2:55 am

Hi Rafal, wasn't ignoring you here... I don't know some of this stuff either, learning as I go! :)

You did find the right param to adjust for speed in PH. It's also in QGC under Special Settings, Navigation Max Speed. You could also try increasing the throws on your radio for roll/pitch, though possibly at the expense of some precision. Be careful if you extend the range a lot... it should be OK but test carefully before you go flinging the multi around like crazy. ;)

As for sinking during AH and horizontal movement, it could be a number of things. If you can't tune it out with Nav. Alt. Position and Speed PIDs, then it could be due to poor sensor calibration. You could check this post for some more information about checking calibration (besides what's already in the docs): viewtopic.php?f=35&t=2250&p=12277&hilit=magnitude#p12080 Also a related and very informative post by Bill regarding mag calibration: viewtopic.php?f=35&t=2286&p=12454&hilit=magnitude#p12454

Logs, pics, video... those will all help us help you. :)

Cheers,
-Max
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Re: speed and alt in Alt/Position hold mode

Postby Ruffio » Fri May 10, 2013 9:32 am

Max, thank You for answer.

I missed "Special Settings" tab, Navigation Max Speed parameter in GCS. THX for confirm.
Of course speed AQ up is one of my goal. I expect a few "problems" with other parametrs like "Dangerous divergence" http://forum.autoquad.org/viewtopic.php?f=36&t=2082.

Post about checking callibrations is realy grate (I did wroted about it) but about mag calibration I missed. Thanx.

Loosing alt is now my proiority and of course I will share success or defeat.

Regards,
Rafal
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Re: speed and alt in Alt/Position hold mode

Postby chschmid » Fri May 10, 2013 10:31 am

Ruffio wrote:I expect a few "problems" with other parametrs like "Dangerous divergence" http://forum.autoquad.org/viewtopic.php?f=36&t=2082.


Regards,
Rafal


Hi Rafal

I do not know how far your AQ project is. But after a good calibration following the wiki you should be able to fly very nice with standard settings unless you have a special Multi layout.
Make sure to have well balanced props with as little vibs as possible.
Follow Angel's findings for the finetuning. LOG is a very powerful tool to do aftermath and locate problems.

When you System is finetuned, start with your Speed Goals, but Keep in mind that AQ is made for stable flights and therefore has some limitations for speed. You MUST NOT tilt too much.

bn999 wrote:Ok, professor Stein :), no one's ask that question yet.

The max tilt angle is controlled by the these two parameters:

Code: Select all
#define DEFAULT_CTRL_FACT_PITC      0.05f       // user pitch multiplier
#define DEFAULT_CTRL_FACT_ROLL      0.05f       // user roll multiplier


They are multiplied by the elevator and roll channel data from the radio. So if you're radio produces -750 to 750 output, your max tilt range will be +-37.5 degrees.

While there is room for more tilt, be careful as you get to much higher values. This theory of operation breaks down as you approach the 90 deg singularities. For any accuracy over 45 deg on more than one axis, you will need to ditch the PID controller and go with something quaternion based.



You will succeed. :)

Cheers
Christof
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Re: speed and alt in Alt/Position hold mode

Postby Ruffio » Fri May 10, 2013 12:33 pm

I'm sure I will succeed, with Your precious help :-)

About horizontal speed and angle - I had a situation flying in realy strong wind (about 7 -10m/s). I now it was not very smart, but it was important tests.
Default NAV_MAX_SPEED was 5m/s.
It was no matter if copter flyes into the wind or with the wind - speed was constans.
When copter flyes with the wind it was very interested when angle of attac was in revers direction than fly direction :-).
It is pity I did not have a video recording of this test.
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Re: speed and alt in Alt/Position hold mode

Postby LPR » Sat May 11, 2013 4:13 am

Ruffio

Thank for asking the question about Max speed. On my octo I set Navigation Max speed to 20 and man you can get moving. At full speed I started to lose a little altitude. I find you have to slow down slowly or you get some up and down movement.
To get the octo to speed up faster I increased the Navigation Speed I to 0.007 and Navigation Speed IM to 30, and OM 40.
Only do this if you have a lot of props on hand and a lot of stick time on multicopters.
Lots of fun and I did not break anything, this time.

Larry
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Re: speed and alt in Alt/Position hold mode

Postby Ruffio » Sun May 12, 2013 10:13 pm

Larry, thanx for share your settings.
I decided to rebuild one of my copter (HEXA) because of poor magnetometer performance - ESC goes under motors, power lines rebuilted.
Where can I read about IM,OM meaning, in serch I found no result?

And 2nd, I didn't change previous calculated parameters (just test) and in Alt/Pos hold copter lost alt when flying forward. When flying backward increase alt.
When flying left/right alt is constance.
This is regular HEXA X, default mix, all motors are same level and same angle (horizontaly and verticaly), CG is in the middle. Baro is under GPS house but not covered by the sponge. If there will be covering baro problem HEXA should always lose alt. Where to look at?

After calculating new parameters I will do new attempts and share logs.
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Re: speed and alt in Alt/Position hold mode

Postby Max » Sun May 12, 2013 10:44 pm

Ruffio wrote:If there will be covering baro problem HEXA should always lose alt.


Why would you assume that?

Assuming your FC is NOT under a dome, if the baro hole is facing your flight direction, you're forcing air into it and are now partially measuring air speed instead of purely ambient pressure. In reverse you'd crate a bit of suction around the pressure sensor opening.

The foam also keeps sun/light off the sensor, which is very sensitive to that. Put the foam on.

-Max
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