Jason, Gigio and I just got back from a day of test flying four ArduCopters, which is the most we've ever had out at one time. These were of different designs, with different props, motors, ESCs, batteries, frames etc. The point was to try to see why some people have great-performing ArduCopters and others have issues. We assumed it was due to hardware differences, but we needed to test to know more.

Unfortunately, the wind was around 20Mph, gusting to 30, so it was a pretty tough environment for flying. Serious stress testing! We had our share of "hard landings", but all quads lived to fly another day.

Here's what we learned (and are doing):

  1. Quads with the gyro filters enabled do seem to fly better, but this seems to be most obvious only if they've got vibration issues to begin with.
  2. Balance your props! Out-of-balance props lead to vibrations that can cause IMU errors to accumulate, leading to the "I have to hold the stick all the way over to stay in place" problem. Jason is going to put a better software filter on the accelerometers to try to compensate for that, but the main difference between good-flying quads and bad-flying ones seems to be vibration.
  3. While you're at it, double check that your motors and props screws are tightened down. Check them often. We had one motor fall off in flight (d'oh! It wrapped itself around the one arm on way down and pulled out a wire. need a new motor now) and one prop fly off. One of those (the former) was mine, so I feel pretty dumb about not checking.
  4. We've fixed that bug where the quad gains altitude quickly in alt hold at the transition between using the sonar and the baro sensor. That will be in the next code pushed in a day or two.
  5. Position hold ("loiter") in 25 mph winds is hard ;-). Jason is going to tweak the algorythm for that situation, where the quad has to tilt by 20 degrees just to fight the wind. That's near the max angle of tilt in the code, so if it gets blown downwind, it can't tilt further to come back. For these kind of steady-state tilts, he's going to allow it to tilt further to return to position.
  6. Something I learned: if you want to reset "forward" in Simple mode, just disarm the motors, point the quad in the direction you want forward to be and rearm. That will reset the direction.

 

Jason is going to be releasing 2.0.24 in day or so. If that solves most of these issues and passes beta testing, we'll take AC 2.0 out of beta!

 

 

 

 

 

 

 

Views: 388

Comment by Ritchie on June 11, 2011 at 5:46pm

Good going guys

You might have fixed the problems before I've even built mine :D

Comment by CyborgCNC on June 11, 2011 at 6:20pm
Thanks for that report chris. The code is awesome, is all I can say, even with these minor issues. I tried kk, uavx, pirates....nothing compares to this code for stability, ease of use, and features! The team here is rewriting the book on what quads can do, and to think that this is only the beginning, makes it all the better....

Thank you all for all your hard work you put into this project, and i look forward for all the more great things to come....

Distributor
Comment by Dany Thivierge on June 11, 2011 at 7:02pm

Great report indeed... I am quite happy with my 2.0.23 with gyro filters pads soldered so .24 will be sweet! 

I have one question around balancing props... no no I am not asking how/why and all... I did mine and it's all fine... What I am wondering is whit the addition of the prop savers  (washers and nuts instead of the "regular" prop holder) would that unbalance the entire thing or not? They come handy as they do really save the props but will it make the quad unstable? 

If no one is able to comment on those I will probably test it out as I have both systems, just need to swaps it out. 

 

Great work guys! keep up the awesome work and we will keep reporting and flying!

Comment by Russell B. Sutton on June 11, 2011 at 7:05pm

Awesome!  Everything you talked about seem to be what caused my quad to crash earlier this week.  I had all these issuse. 

@ Chris  LOL " I hate it when I do that"  Sorry to hear about the crash. 

Comment by I.S. on June 12, 2011 at 1:58am

I had some strong wind issues, so really looking forward to steady-state tilt.

 

It's not only the great code you make but the pace you keep.

Thank you (all the team) for every test, feature, fix, tweak you make.

Comment by I.S. on June 12, 2011 at 2:00am

About the filtered gyros: I heard that filtering gyro signal will be bad for DCM algo effectivity.

In which occasions you recommend enebling filters?

Thanks again

Comment by Peter Seddon on June 12, 2011 at 2:28am

Dany, Not sure what type of prop savers you are intending using but my experience is that they cause more problems as the prop is not held rigidly to the motor. I flew with them and had every problem in the book. Changing to proper prop adapters cured virtually all my problems. 

 

Peter


Distributor
Comment by Dany Thivierge on June 12, 2011 at 5:22am

I was referring to these http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...  (not sure of the size I got but mine fits nicely on the jdrones motors... 

 

I will use them on and switch back to prop adapter and report how it is...

 


Distributor
Comment by Dany Thivierge on June 12, 2011 at 5:23am
Oh another thing... will the motor LED code be changed/upgraded in non beta version? I know Jani was working on this a bit... I agree this is just nice to have and fly stability is more important than lights but it would be nice to see this working for "final" version.   Actually only the rear one blinks...
Comment by Paul on June 12, 2011 at 6:26am
hey chris, good to hear about the progress. i just noticed in the http://code.google.com/p/arducopter/wiki/AC2Assembly - Covering the barometric pressure sensor. ive just noticed this, does this still apply and recommended?

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