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3D RoboticsPermalink Reply by Chris Anderson on June 8, 2011 at 2:04pm

Thanks for the beta test report. Alt hold is something we're working on is being revised in 2.0.24.  It should be pretty solid at all altitudes by the time we take AC2 out of beta in a week or two.

 

I assume you checked your altitude sensor readings in the CLI test menu and they looked fine. 

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Permalink Reply by vaeddyn on June 8, 2011 at 2:12pm

Yup - well, at least as far as I can tell eyeballing it.  Sonar is pretty accurate as I move the copter up and down from my desk/floor, not much fluctuation.  Baro has a lot of noise to it but it does appear to be working.

 

I would love to be able to see what it was reading in the air.  Guess telemetry is my next hookup.

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Permalink Reply by Jim Phoenix on June 8, 2011 at 2:40pm

I first flew my Arducopter without sonar and baro alt hold worked pretty good, a couple days later, I installed sonar and my experience is exactly the same as yours now, sonar hold works good, but when it gets out of sonar range, it climbs until I return to stab mode. See my videos, one is baro alt hold, the other video is sonar alt hold and you can see the quad climb when it loses sonar lock.

Www.rofldrone.com

Jim

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Permalink Reply by vaeddyn on June 8, 2011 at 8:55pm

Jim - come to think of it that's exactly my experience too, my first flights were baro only and I didn't see this happen, it only started after the sonar went in.  Good catch.  I'm going to try and disable the sonar and see if baro hold comes back.

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Permalink Reply by Jim Phoenix on June 8, 2011 at 9:55pm

Let us know how it works, I'm curious if that is the problem.

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Permalink Reply by Al Ros on June 8, 2011 at 10:56pm

Hi Guys

 

I was testing Alt hold tonight and loiter. What I found was the sonar worked much better if during power up it had a foot or more off the ground rather than sitting on the ground.

Also If i activated altitude hold when the quad was in the sonar range, it held altitude well, then I activated it when I was well above sonar range, and it also held reasonably well by baro. However, in one of the tests I think I was around the boarder between sonar and baro, and the quad did what you guys described. For a few seconds it held ok presumably with sonar, then it rose slightly to what I think was into the transition altitude zone, at which point it shot up at near full throttle

 

can you guys confirm if yours will hold well when low in the sonar altitude range and when fairly high in the baro altitiude, then check the middle transitiona altitudes?

 

p.s. I have mag and GPS enabled

Thanks

Al

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Permalink Reply by vaeddyn on June 8, 2011 at 10:59pm

in my case:

• If started in sonar range, it holds well.
• If started near the top of sonar range and fluctuates out of range, it takes off
• If started up high in baro range, it takes off.

I haven't done an exhaustive test but that's my observation at this point.  Tomorrow assuming weather cooperates I plan to test a bit more and also try running with the sonar disabled and see if anything changes when baro's all it's got to work with.

 

For what it's worth, I have never powered up when not sitting on solid ground and my sonar hold is great.  In what way is it working better if you boot up a foot in the air?

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Permalink Reply by vaeddyn on June 9, 2011 at 5:12pm

Update:  Today I removed the sonar (which, as I never specified, is an LV-MaxSonar-EZ0 from the diydrones store), disabled it in the CLI through APM Planner, and went for a flight.  Altitude Hold and GPS Loiter now work at all altitudes I tested, I could not get the copter to take off vertically the way I'd seen before, it held onto its altitude well though with more fluctuation than I saw with the sonar at low altitudes.  I would expect that to be the case.

 

In alt hold mode I was even able to maneuver a bit aggressively and it sustained its alt.

 

It looks to me like at least with my sonar unit, the copternever seems to pay much attention to the output from the baro.  As much as I miss my rock-solid low altitude stuff I think the sonar's going to stay disabled for now until we know more.

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Permalink Reply by John L. on June 9, 2011 at 6:22pm

I have the LV-MaxSonar-EZ4 mounted and don't seem to be getting consistent altitude hold at lower altitudes.

I noticed that now in the manual it has the XL series shown.

Are the output scalings the same between the 2 series?

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Permalink Reply by Limebear (Rob) on June 10, 2011 at 1:35pm

The advantage of the XL over the LV, is that when you power up the LV it calibrates and needs to be at least some distance away from anything (about a foot I think, see datasheet) which is a pain, because it means holding the Quad off the ground every time you connect the battery, which needs 3 hands. The XL doesnt have this restriction, plus it has other advantages, except for higher cost! Yes, it seems the LV has been quietly dropped.

Rob

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Permalink Reply by Al Ros on June 10, 2011 at 9:42am

Ok very interesting - I will try again - I just received an XL sonar

 

Al

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Permalink Reply by Vincent Mees on June 10, 2011 at 12:11pm

Also just received my sonar.

It works veru accurate but in the planner I get 33 cm when the sonar is against the floor. Also the alt err is 33cm.

It seemsit doesn't go below 33. Is this normal?

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