Tricopter PID`s Help

Anybody had any success with APM2.0 and a Tricopter? after much messing around with PID`s I can get it to RTL in a fashion 70% of the time but once it gets bak to Launch it tends to lose it bearings and dissapear in another direction and I have to switch into stabilize mode before it crashes and the same with loiter it will hold the height most of the time but never the position, somebody please help..

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  • So I upgraded to 2.7.1 and tried using the stock configuration.  After three batteries, here are my thoughts:

    Stable mode isn't too bad, it's definitely flyable.

    Altitude Hold isn't working as well as it was before I upgraded.  Before it was rock solid, now it's just OK.

    Yaw is acting weird - it's super sensitive to the stick counter-clockwise, almost hard to get to turn clockwise.

    Loiter isn't working well at all, I always get a fairly rapid drift to the East/Southeast and have to switch out of Loiter mode.

    I didn't have the guts to try Auto mode - I figured I'd better get Loiter working well first.

    Attached are the log files from a typical flight.  I'm assuming I've got some PID and parameter tuning to do.  Unfortunately, I won't have much time to dedicate to this for a month or so.

    2012-08-15 19-17 6.kmz

    2012-08-15 19-17 6.log

    2012-08-15 19-17 6.log.gpx
  • OK, new problem.  I just finished rebuilding from a bad crash and I'm slowly getting things working again.  I'm stumped though by something which seems like it should be obvious.  The elevator stick on my Tx is causing the opposite movements that it should.  That is, when I push the stick forward, the front motors speed up.  When I pull it back, the back motor speeds up.

    At first of course I thought this was a Tx configuration reversal thing, so I went into the MP's Transmitter configuration and redid it.  Everything looked kosher, push the right stick up and the "Pitch" green bar goes up and visa versa.  So then I went and looked at the tuning graph and that's where things go weird.  Here's a video:

    The  weird thing here is that you can see when I push up on the pitch stick (green line) the front two motors speed up (red and blue lines).  Pull down on the stick and the back motor (orange line) goes up.  

    I can of course work around this by flipping the Reverse switch in the Transmitter config, but I'm not sure what else that might impact.

    I'm sure I'm doing something simple wrong here, but can't figure it out.  Thanks!

  • One more question - I'd like to watch in real time what the FC thinks it's doing with the Yaw mechanism.  Since the servo is controlled by channel 7, I just be able to go to the Flight Data window, turn on the Tuning check-box and make sure that ch7out is being watched.  I did that, but there doesn't seem to be any output on ch7out.  I can't correlate the yaw control to any of the out channels.

    Any ideas how I can see what the FC is doing?

  • I got out tonight and flew 3 batteries.  It felt great to be out doors and not get wet.

    These were my first flights with the new 2.6 release and Dean's 2.6 parameter settings.  I'm happy and had a good time (I'm alway happy whenever I don't crash) but it was kind of a mixed bag.  Some thoughts:

    * Stable mode just rocks.  It's almost as good as my Naza.  When there's absolutely no wind and everything is trimmed up right, the craft just hovers nice and steadily.  I'm very happy with it.

    * Given that I just have an altimeter and no range finder, altitude hold does an amazing job.  There's a wee bit of slow oscillating, but it's minimal.  I wouldn't expect it to be this good.

    * Loiter seems to be a bit better.  At least it seems more like a loiter and less like a wander.  When in loiter, I'd say it stayed in a 50m radius.  A bit more than I'd like, but not nearly as bad as in previous releases.

    * Simple mode just doesn't seem to work at all.  I couldn't make heads or tails of what it was doing - moving the sticks seemed to produce totally random directions.

    * Circle mode should be called semi-circle mode right now.  It looked like it just couldn't bring itself to turn that back boom all the way around the circle and face due west.  It'd usually stall around 200° or so.  Then try again.  After several tries I never saw it make it around 360°.  I never saw it face west unless it started in that direction.  Could this be a compass issue?

    * I couldn't get RTL to auto land.  It would head back near the launch area and loiter, but never land.  One time I let it loiter 3 minutes and it still didn't land drop altitude at all.

    * I didn't properly test auto mode.  At the first waypoint it started going up and up and up and I turned it off before I lost sight of the craft.  After I got back down I found that somehow I'd entered 100m for the altitude instead of 10m.  My typo.  Or maybe I forgot to change the defaults.  I'll try it again the next time I fly.

    * Yaw is weird.  I had a fairly difficult time getting the craft to yaw properly clockwise.  Counter-clockwise wasn't too bad, but I could watch the tail motor being controlled by the servo and whenever I was yawing clockwise and stopped by returning the stick to center, the motor would over-compensate when returning to center and turn maybe 20° to the right.  I'd really love to stop that action.  I'll video this the next time I fly.

    * Finally, when I look at my log files, there are some really strange points in space.  I'm not exactly sure what to make of them.

    I had fun tonight, I can't wait to play with it some more.  I've got to learn how to tune some of these things like circle mode.

    2012-06-19 19-49-30.tlog

    2012-06-19 20-18-50.tlog

    2012-06-19 20-45-24.tlog
  • Well the weather continues to be miserable here in the Pacific Northwest.  Every day I'm free it seems to be windy or rainy. If I'm not available to fly, it's sunny and calm.  Hopefully the two will coincide soon.

    While I'm waiting I updated to 2.6 and loaded your 2.6d params.  I assume there were no changes after the delta release?

    I can't wait to fly this puppy again.

  • One more noob question - are all of the parameters defined or explained in the documentation or one place in the source code somewhere?  I can't seem to find it.

  • Thanks for that pointer.  I just downloaded your config file and compared it to mine - interesting.  In general, it seems like you're making the craft a bit less aggressive than the stock params?  For example all of your NAV_* params are much less than the defaults.  All the SPEED_MAX params too.

    Unfortunately it's rainy here today so I won't get to try flying with your params.  Hopefully tomorrow.

    Thanks again!

  • Just went out for my APM2 maiden tonight.  I posted more detailed results in another thread, but thanks for the help here.

    My biggest problem was with the GPS.  I'm wondering a bit if that's an EMI problem too.  I may try some experiments totally moving the battery and receiver away from the APM2 board to see if that helps.

    Thanks again!  I had fun out there tonight.

  • It's the Tim Nilson Delrin kit.  I was going for as clean a build as possible, so right now my ESCs are in the middle deck of the central plates, directly underneath where the FC would go.  Maybe I should give up my addiction to the clean look and move the ESCs out on the arms.

    To keep balance, I'd still have to put the battery on the bottom underneath everything.  That's going to be about 3-4 cm below the FC.  I could put a thin aluminum shield above the battery.  Or maybe under the FC.

  • OK, those videos convinced me to give it a try -  I'll be setting up the electronics in the next day or so.  Anything I should keep in mind while finishing the build or before the maiden flight, other than using the latest version of the software?

    Thanks for the update.  I was kind of wondering what I was going to do with my fancy new APM2 if I didn't put it on the tri.

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