Motor power settings ?
  • Hi !

    Didnt really find any tips on how to set the power on the gimbal motors. Is the best to use much power as long as the motors not getting too hot ?
  • yup that is correct !
  • OK, Thank You. I'll try that right away :-)
  • I got vibrations on pitch when the power was raised. Even after autotune the pitch motor was buzzing. I dont know if I should do some workaround for this or stay with low power.
  • What FW are you using? 2.59 has improved auto tuning.

    Dry different auto tuning settings, if P or D goes to 255 use advanced Gain, try also filters.

    And inspect your mechanical construction.
  • Yes, first 2.59 and now also the beta, 2.60b1.

    The gimbal is a Walkera G-3DH( > 360 degree free movement on yaw). Using 4s and the gimbal is specified 7-28v with the stock controller( I have the DYS 32-bit SimpleBGC with dual IMU's)

    It works fine with lower power setting but raising the power to 100 or more gives vibrations on pitch after running autotune. I was trying to use more power as the motors where very cool and then got vibrations. Dont really know how to find the right power setting. P ended up at very low values after raising the Power(Voltage),

    Mechanichally I think it is quite ok in balance, and moves quite freely. A little(very little) friction might be from the electrical swivels.
  • It sounds like the might be some loose play somewhere. How time is the IMU installation etc.

    If lower power works fine, nothing wrong using lower power, but you could try the filters, also you could lower gain from advanced tab to get P around 100, so the tuning has a bit better resolution.
  • OK, thank you. I'll try to get the P to 100 and also look at the filters.

    Cant feel any play at all except for just a minor play in the yaw engine / bearings. (guess about 5/100 of a millimeter up and down). I will check for play, just top be sure.

    IMU installation: I think it's ok. The camera IMU runs trough the aluminium frame together with the motor cables. I know you should avoid this, but I just had to try to make the gimbal able to free movement. It works ok, I think. I dont get much of I2C-errors. There kan be a few on power up, but I can work with the settings for 10-15 minutes and have about 10-20 I2C errors in total. Holding the quad above the head connected and starting the quads motors dont give any I2C-errors.
    One IMU on camera holding fram, mounted in stock IMU-position, the fram makes its position quite right in angles(should be very precise line up).

  • You should look into the I2C cable routing etc, to get completely rid of I2C errors. Not much related to your Power setting problem, but they will show on video.
  • Ok. I will look into that. Didnt know that single I2C errors could be seen on video, but then I'm new to this gimbal tuning stuff :-)
    I'm using ferrite rings, but current cables to motors are to short for more than one turn around the ring. I will change to longer cables and use at least three turns.
    I2C cables already have some turns.
  • Auto tune seems to give more oscilations than if I manually set the PID.
    Also, the filters seemed to give much higher amplitude if activated.

    When flying the quad I think yaw and roll is quite good, but on pitch there are some rather small irregular oscilation, not yello type, but close. This could be from dampening but as I remember it the stock controller worked fine( = OK) on pitch and roll but was terrible an yaw so my guess is that it should be fixable by tuning.
  • Most often to problems you describe are something else than tuning related. Changing controller should not dramatically change axis performance. The tuning can affect, but more likely something has changed mechanically.

    For tuning, see the filters.
  • Ok, thanks !
  • So, longer cables from motors to controller, making it possible to wind the cables 4-5 turns around the ferrite rings did not change the (quite low) amount of I2C-failures but if I disable the frame IMU(disabled in Basecam software, still mounted) there is no I2C failures at all.
    I don't see why ?

    I tried working with lower gain in advanced tab to get higher P, but it wouldnt go up to 100.

    P I D after autotune for the axes, with power set close to temperature limits(60 degree C?). They're about 50-55C now:

    Roll P: 58 I: 0.85 D: 60
    Pitch P: 30 I: 0.54 D: 18
    Yaw: P: 77 I: 0.63 D: 71

    I think Roll and Yaw works fine, but pitch is not smooth, giving a little shaky video.
    If I use the monitoring tab and increase the scale to max I can see that error for roll and yaw are small( mostly zero) if I hold the quad by hand in the air, but the pitch is not that smooth(error changing betwen - and + 4 to 6).

  • So, I dont se why I don't get I2C errors when the fram IMU is 'disabled' in the software but still connected. The fram IMU does not have any cables routed clos to motors or anything at all. (The camera IMU have cables routed together with motor cables inside the aluminium parts of the gimbal frame, through two slip ring connectors etc.) Might the frame IMU be faulty ?

    And I found some slop when following Garug's tips to look for it. It's fixed now and the only minimal slop still around is in the Yaw motor/ Yaw bearing. It is not much, I guess its about a few hundreds. I dont know if I can take it apart and fix without braking anything.

    Video looks much better now, what still pussels me is that there is a little shaking in pitch that can be seen in the video. I dont now if it comes from the slop, the pitch settings or the gimbal dampening...or probably, a combination... ?
  • I did just read this in the basecamelectronics site:
    "The lower is the value of Power, the better is the stabilization, but resistance to external influences is worse (such as bad balance, friction, air flows, etc.)"

    The pitch axis is very smooth, light Weight and balanced. There is only the weight of the Hero4 Black and a ND-filter(when mounted the pitch axis is in perfect balance), and som very small parts of aluminum so the power needed should be low. Perhaps go the other way around and try to use low power?
  • This is how it looks when holding the quad in the hand:

    This is same settings, quad standing on the table:

    There should be a reason for the pitch axis not holding as smooth as the other two.
    Lowered the power from 80( temperature limited) to 25. Now I get the P up to around 80 but the error in Yaw didnt change much.
  • Used manual tuning instead and worked with power as well.
    Ended up with power 40, and way more P and I then autotune and quite smooth in the monitoring tab. That actually made the big difference, now it produces ok video.
    The pitch motor makes some noise(buzzing) but only get about 32 degrees Celcius. Is it ok to use a setting that causes the motor to buzz ? ( cause right now I cant make the buzz go away and keep the smooth values in monitoring tab)
  • I've just updated to 2.60B4. The autotune seems to do a much better job than before.
    There's still some vibrations in pitch. Sometimes none, sometimes a little. I dont know if it is a setting or if it is vibrations that need to be damped better.

    I will make a movie, perhaps someone can tell from it where to contine the work...
  • Back tuning again after the winter.

    Not at home but studying the net and found ppl saying that the IMU shouldnt be mounted with double sided tape( not solid mounting enough?). I did mount the IMU in the stock IMU position for the IMU, but I did use double sided tape. Will check it up, per memory the only axle that the mount for the IMU doesnt support 100 % is pitch axle so a problem there is possible.

    Before I modded the gimbal it was really good at pitch and roll and actually the only part i wasnt happy with was yaw. Movement wasnt smooth but a bit choppy. Not all the time but enough to make me not happy. After the mod yaw became perfect and roll at least as good as before. This without any hard tuning, only used autotune and it was good.

    For the pitch, it doesnt seem to help with any settings. Autotune or manual, pitch still is not smoth when flying the quad. Can make it smooth and nice on the table.

    Mechanically nothing other is changed, balance is good(it was not stock, but I'did work a lot with this). I can leave the camera in any position and shake the quad, it doesnt change. For pitch, the balance is at least as good as the other axis.
    There is no slop on pitch axis and almost no friction.

    For now, I have deselected the frame IMU, and then there is no I2C-errors. I guess that the other axis would not perform good if there was I2C-errors present.