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Question Wobble up and down problem as soon as I plug in USB cables

Discussion in 'DIY Motion Simulator Projects' started by motiondynamics, Dec 17, 2022.

  1. motiondynamics

    motiondynamics Member Gold Contributor

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    Hi noorbeast,
    Let's see if I understand correctly: Has the wobbling problem in Simtools V3 been fixed?
    But the problem of the oscillation of my simulator arises without using Simtools, that is, I explain better:

    I connect the power supply of the electronics (BLDC drives + Arduino), I turn on the computer, connect the 2 USB cables and suddenly the oscillation of about 5 millimeters up and 5 millimeters down starts with a time of about half a second up and half a second down . So without using Simtools.

    Hello Tomsix, yes it is certainly not possible to know many languages, this was not my request. I just wanted to say that: since this defect has been reported by other users as well, it would have been better if the problem had been solved directly on the SMC3 code, not changing the Windows language.
    It's like having a flat tire on a car and trying to fix it by inflating it every time. No, it would be better to repair the hole in the tire. No?
  2. Gadget999

    Gadget999 Well-Known Member

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    just send a video of the problem
  3. motiondynamics

    motiondynamics Member Gold Contributor

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    I will try to send you the video (but I don't know if I can...)
    Some screenshots of SMC3Utils with the defect will be easier to send you. Already I can immediately tell you that when the oscillation problem occurs, the green line (potentiometer) of SMC3Utils is not linear, but makes very small curves up and down, up and down, constant (like a sinusoid, but very small and flattened).
  4. superwhitewish

    superwhitewish Member

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    Hi, can you tell which bldc motor controller that you are using?
  5. motiondynamics

    motiondynamics Member Gold Contributor

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    Homemade BLDC controller operating frequency 1Khz
    • Like Like x 1
  6. motiondynamics

    motiondynamics Member Gold Contributor

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    Hi everybody.
    I carried out the first tests to locate together with
    you the cause and resolution of the problem:

    This is the 1st test: I removed the 100 kgm payload, the simulator swings up and down by 2mm (2 down, 2 up) constantly.
    As soon as I put on the 100 Kg payload, the oscillation ends (see the graph)

    What could be the cause?
    How could you solve the problem?

    Attached Files:

    • 1.jpg
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  7. Gadget999

    Gadget999 Well-Known Member

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    Set pwmmax and pwm rev to 255

    Set frequency to 20khz

    Reduce kp to 1

    Not start a sine test

    Slowly increase kp till it tracks correctly
  8. motiondynamics

    motiondynamics Member Gold Contributor

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    Hi Gadget999, I did the test you suggested. Now the motors are stable, they don't oscillate (with SMC3Utils running).
    But as soon as I close SMC3Utils, after about 15 seconds it swings up and down constantly, 2mm down and 2mm up.
    I am using version V1.0
    How do I attach the video of the problem here?
    I tried to insert the video of about 1Mb (Avi, MP4) but it won't let me upload the video.
  9. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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  10. motiondynamics

    motiondynamics Member Gold Contributor

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    Hi Gadget999, I did the test you suggested. Now the motors are stable, they don't oscillate (with SMC3Utils running).
    But as soon as I close SMC3Utils, after about 15 seconds it swings up and down constantly, 2mm down and 2mm up.
    If I put a weight of about 25Kg on the actuator, it stops oscillating.
    Sto utilizzando la versione V1.0

    I am using version V1.0
    Last edited: Dec 29, 2022
  11. Gadget999

    Gadget999 Well-Known Member

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    What happens when you open the sim game and motion starts ?
  12. motiondynamics

    motiondynamics Member Gold Contributor

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    When I start "Assettocorsa" the engines position themselves well, in the centre, they don't oscillate. All perfect.
    The problem occurs only when I connect the USB cable, without using SMC3Utils, without using Simtools.
  13. Gadget999

    Gadget999 Well-Known Member

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    Try a bigger kd number
  14. motiondynamics

    motiondynamics Member Gold Contributor

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    I have now tried putting Kd 100.
    But the problem is still there
  15. Gadget999

    Gadget999 Well-Known Member

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    Unplug the potentiometer, does the oscillation dissapear ?
  16. motiondynamics

    motiondynamics Member Gold Contributor

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    Do I have to disconnect the potentiometer??
    But if I disconnect the potentiometer I no longer have the feedback...
    Do I have to disconnect the 3 potentiometer wires (gnd, 5v, out)?
  17. Gadget999

    Gadget999 Well-Known Member

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    Disconnect any wire and see if the oscilation stops
  18. motiondynamics

    motiondynamics Member Gold Contributor

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    I carried out the test of disconnecting the potentiometer: the actuator goes all the way down until it hits mechanically (mechanical stop). I put the potentiometer in right away to avoid burning the motor or the electronics.
  19. motiondynamics

    motiondynamics Member Gold Contributor

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    Dear friends, I showed you the video, I explained the tests I did, but nothing, the oscillation problem doesn't go away.
    The strange thing is that the oscillation is done without using software (SMC3Utils or Simtools), i.e. as soon as I connect the usb cable the motors go to the center (ok), but after 15 seconds the interminable oscillation starts which is very annoying.

    The question is: is it possible to modify the SMC3 V1.0 code, so that the movement of the motors starts only when you start the game?
    That is, is it possible to prevent the motors from activating as soon as the usb cable is connected?
    It would be enough to do this already, because then when I start AssettoCorsa, the oscillation disappears.

    Is there anyone who could tell me what to change in the sketch?
  20. Gadget999

    Gadget999 Well-Known Member

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    The oscillation is coming from your bldc driver imo

    The way to fix it it to time the interval of serial inputs, if the interval goes over 2 seconds then shut the motors down