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Permalink Reply by malcolm churn on July 9, 2012 at 5:46am

Off out again today to tune the ALt_hold, If i can get that to work well then the Loiter should be a lot easier to maintain. If all goes well and i can get down to see martin, i'll start using the xbee's for data transmission.

As for accuracy, i dont really know yet, but i'll keep testing. 

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Permalink Reply by malcolm churn on July 11, 2012 at 2:03pm

This is a great video showing the DJI Ace one against the Align APS system, I'm hoping that i can get somewhere near to this with the Ardupilot H. The Align system looks pretty good to me @ £499 against the £2500 of the DJI, if i can get the APM @ around £200 to work as well as well as these two systems then i'll be really happy. 

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DeveloperPermalink Reply by R_Lefebvre on July 11, 2012 at 2:47pm

Interesting.  Here's the only 3rd Party review I've seen yet:

http://www.helifreak.com/showthread.php?t=433504

You won't get anywhere near either of those performances with APM, at least not with the Mtek GPS.

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Permalink Reply by malcolm churn on July 11, 2012 at 3:46pm

So just to be clear, will the APM never hold my heli in a reasonable Loiter?

Randy was talking about the new Ublox. But after your statement above i wonder if its ever going to happen.

Well i'll test again tomorrow, maybe randy can shed some more light on this.

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DeveloperPermalink Reply by R_Lefebvre on July 11, 2012 at 3:54pm

In wind like that? I don't think so.  I have seen a few cases, but it seems like some magical alignment of the planets and is not repeatable.

Those guys MUST be using inertial dead reckoning, and we haven't been successful with that yet.  And I'm not sure we're going to get there with APM2.  With the ARM board, maybe.

In my opinion, we've maxed out the processor, and just can't do much more with it.  These other flight controllers are not burdened with all the same features we are.  The APS actually operates ON TOP of the Align 3GX.  So the 3GX is still doing rate control, and the APS is only doing Nav.  We have one flight controller doing everything, including logging, telemetry, etc. etc. etc.

But simply put, if you are hoping to get that performance out of the APM, I think you'll be disappointed.  At least as far as anything I have seen.  But I could be wrong.

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Permalink Reply by malcolm churn on July 11, 2012 at 4:13pm

So why dont we use a decent flybarless controller and use the APM for level control and nav?

Just a thought.  :)

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DeveloperPermalink Reply by R_Lefebvre on July 11, 2012 at 4:26pm

Yeah, you could do that.  But I still don't think it will fix the Loiter problems.  I could probably give you a code that would do what you want in a day.  But fixing Loiter is a much bigger problem.

Maybe once we get the DMP program running we will free up the overhead to run inertial nav.  We'll see.

But also, needing to slave the APM to an FBLC is really not the intent of the system, so nobody has considered it.

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Permalink Reply by Wesley Chuen on July 11, 2012 at 5:17pm

I think that's a great idea.  Most of my problem with the APM2 are just simple flying issue such as yaw stability and vibration/wobbling issues.  If APM2 only provide the direction and pitch (altitude) control, and not to try to do any "stability" stuff, it would make things much easier.

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DeveloperPermalink Reply by R_Lefebvre on July 11, 2012 at 5:21pm

I've solved the yaw stability problems.  You guys should get it in the next code.

I'm not quite sure what they are going to do for quads, etc, but I'll push it myself for helis if I have to.

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DeveloperPermalink Reply by Randy on July 11, 2012 at 6:10pm

I think it's possible we can get close to that level of performance...but the thing is, can they even consistently get that level of performance?

It looks like no wind, very low PID values in a no wind situation will give you a smooth loiter.  It's just that when the wind picks up you'll drift off.

They're also having some trouble with the alt hold right at the beginning.  It starts falling and then you hear a little 'beep, beep' probably as the pilot increased the throttle trim and then the copter recovers.

So I'm not so sure they're using any inertial compensation..i think they've just tuned it to that particular environment well and taken a video.

I think the new GPS will definitely help with loiter performance..although I also think it's time for us to move onto way points!  It's so much more fun than just simple loiter!

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Permalink Reply by Wesley Chuen on July 11, 2012 at 6:45pm

For me, the fail safe auto return home and land would be the best.  Can APM2 on heli can even land?  I know landing a heli is tricky.  I doubt it is even possible with APM2.

The reason I ask is that I recently tried multicopter.  The stability of it is mind blowing compare to helis.  I tried the fail safe auto land and it worked almost like magic.

http://www.youtube.com/watch?v=MAHfgxZyViU

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DeveloperPermalink Reply by R_Lefebvre on July 11, 2012 at 7:04pm

Wesley, that's a really good performance.  Is that APM or DJI?  It looks like a DJI nav puck mounted up high.

You think the multi is more stable than a heli?  I actually didn't find that.  My flybarred 600 is at least, if not more stable than my 3DR quad.  Especially during descents.  The heli, you can hear the turbulence when descending, but it doesn't upset it much.  The quad really wobbles.

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