Arducopter 2.8.1 Test Flight on 450 FBL

I now have 2.8.1 code working for TradHelis. For anybody who has not been following along, this now brings attitude rate control to TradHelis for the first time. When combined with Leonard and Randy's Earth to Body frame rate rotation algorithm, the performance is excellent! Please watch this video, and remember this is a flybarless 450 heli. Normally these fly like a rabid squirrel!

http://youtu.be/zYpq8fXuaGI

Sorry about the shakiness and my daughter's commentary, she had to come out with mommy and daddy. ;)

It is now really easy to fly around very sporty, yet precisely even at high speeds. It has no nasty tendencies. There are a few spots where I zoomed upward, but that was completely intentional.

The only weakness I can see is an occaisional "bobble" of the pitch axis at high speeds, but this is actually present with many professional FBL controllers. I may be able to tune it out yet.

There is still ongoing work, but it's looking really promising!

Rob

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  • Developer

    What pids are you guys running for a trex 600 FBL? a param file would be good

  • Well, I just bit the bullet and ordered Assymetrical rotor blades for all my helis.  Can't wait to try them out!  I should be able to double my flight times.

    I ordered 325, and 600's plus 95mm assym tail blades.  I also ordered some 710's and 105's for the radical camera-ship design I'm working on. :)  Unfortunately this is going to be closed-source.  ;)  It's pretty extreme.

  • Two more battery packs last night, tuning up the Alt_Hold gains even more.  Alt_Hold is working totally awesome.  Last night, from a hover, I push the stick hard over to the left, and the heli zips off to the left only losing a few meters of altitude.  Then when it's moving fast, you can throw the stick hard right so the heli comes to a screeching stop, and it rises just a few meters.  I'm not sure I can do better myself.

    It's actually almost surreal flying like this now, not having to manage the collective.

    I'm pretty sure we will now be able to fly missions at 20m/s without all the problems we had before.  It might still get into an altitude/velocity oscillation called a "phugoid" but I don't think it will simply crash into the ground as before. 

  • I just tested 4 more battery packs on my 450, this time testing what is to become 2.9 release (all the changes I've talked about in this post still apply.)  The main difference being that I used the new Accelerometer augmented Alt_Hold.

    My testing showed it was good, really REALLY GOOD!

    Major props to Randy and Leonard for all their work on this.  Simply put, the altitude is rock-solid. Very stable even with the flighty 450.  I was expecting to have some problems, and have to hack it to get it to work on a helicopter the same way I had to for rate based attitude control, but I didn't.

    I even tested it in some fast forward flight, and it was perfect.  I could just cruise around the skies without touching the cyclic.  Even if I got going forward fast, and pulled back hard on the cyclic, it only gained about 10 feet, and I'm still working on tuning it, I think it can get even better.

  • In testing, I've had some evidence to support the theory that the much stronger filter I'm running in the MPU6000 will make this much more resistant to "leans".  I can hear a noise that makes me suspect a bearing is going on the 450, it's got that slight buzz to it.  But I had no problems with the MPU filtering at 10Hz.  Last night, I changed it back to the standard 98Hz filter, and I instantly had about 20° "leans"!  I put the filter back at 10Hz, and the leans were gone.

    I plan to release the next revision with the default TradHeli filtering rate at 10Hz.  This is obviously a HUGE deal if we've solved this problem!

  • Looks great.  Is it recommend to run a flybarless setup now?

  • Just test flew the latest.  It's so good I want to cry.  I can't wait for you guys to try it!  

    I even got rid of the tail waggle I always had!

  • Awesomeness!

    I've just come down from the loft with the remains of a blade400. I will get it flying like the rabid squirrel that it is then steal the APM 1 off the tri. 

    I need more APM's!

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