Fligth tests results with Ap/arduimu combo

I did some more flight tests and had mixed results.

Bear in mind that I only have interest in the stabilize mode and RTL mode (FPV in mind with a streamed easy glider treated to fly with the minimum of loss which means all the electronics inside except the RC antenna).

The test model is a Mpx Magister.

1st thing I discovered is that, to contrary of the Ap code version 1.x, this 2.6.1.1 version I am using in the Ap didn't assume the trim regulations we have in our radio Tx.  I had to adjust mechanically the model rods in order to have a model flying true with trims at zero, because when the stabilize is selected, the servos assume 0º in spite of the trim regulation we have stored in the radio. 

2nd The RTL mode works relatively well, did only small range tests but the model always return to my position.

3rd The stabilize mode work well... and very badly.

I explain, the rc input seems like it has (large) expo dial in, so we have some sort of have it all (which brings some instability due to excess reaction of the arduimu) or almost none.

The other problem with stability mode is the reaction to the throttle input.
If we are cruising with some speed or at WOT and  the stabilize mode is activated,  the model pitch down dangerously and we can only save the model returning to Normal.

If the stabilizing mode is active and we advance slowly the throttle, the model slightly pitch down but then maintain the height.

Now, in a situation of Fail safe with RTL enabled, this can be a severe problem if the RTL engage full throttle.

Found also that with stabilize mode active, the model steer well in the sky using the rudder, but steering with ailerons can bring some  problems, to the left the model steer hesitantly but steer, to the right the model fight against the rc input, rise its nose and fall from the sky, saved again by the Normal mode.

All of the above was tested with stock code (Ap2.6.1.1 and Aimu1.7).

Tweaking the code is  necessary to:
1. Smooth the Rc input looking for linearity (reducing the filtering in the rc input, but how?)
2. improve the stabilize mode (can be tweaked but not a easy, this 2.x code is much more complex than the previous 1.x and I am having some trouble to understand it in order to change something in the code )

 The above is not rant, only my 1st impressions about Ap/arduimu combination.

I know I have a lot of work to do in order to improve the results.

Any how, THANKS for your hard work.

PS.
This discussion could be posted in this sub-fórum or in the Ap forum, I decide to put it here, if you think this is the wrong place, pls change it.

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Replies

  • Developer
    Most of your issues appear to be tuning related. Gain values that worked well with versions prior to 2.5 will not work well with 2.6 or later. The uneven turning left to right is most likely due to inaccurate min/max radio values. Tweaking the code should not be necessary. Working on the parameters in the header file is where you should turn your attention. With properly tuned values in the header file 2.6 will fly your plane better than you can.
  • Developer
    I have some updates I'll be releasing tonight that should address many of these issues. I too fly a stripped down version for FPV.
    I can't say about the pitch throttle issue, I'll let Doug talk to that.
    Jason
  • Moderator
    Jalves,

    Check out this thread. There is a lot of good information here about the problem you are experiencing with relation to gyro drift with acceleration. Pay particular attention to the reply by Doug Weibel on June 9, 2010 at 5:02pm.

    Good luck
  • 3D Robotics
    As for the trim settings, if you set this to 1 you can teach it your radio limits at startup:

    //3-1
    #define SET_RADIO_LIMITS 0 // 0 = no, 1 = set the limits of the Channels with the radio at launch each time;
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