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Jonota - 3 DOF (or is it 2 DOF w/Traction loss?)

Discussion in 'DIY Motion Simulator Projects' started by Jonota, Oct 18, 2023.

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  1. Jonota

    Jonota Semi-jack of all trades, master of pun

    Joined:
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    Nuclear
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    Kansas
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    95Coins
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    +3 / 0 / -0
    My Motion Simulator:
    3DOF
    It *appeared* that it was easy to adjust the pin #8 vs. #9 - but time will tell.

    Now I'm into the testing portions. I was able to figure out verify/compile/upload to the arduino and everything seemed to go well there. I then went forward with the SMCutility testing and ran into several problems.

    First problem is mechanical - I used hot glue (specifically the strong stuff for automotive dent repair) to connect the motors to the potentiometers. I didn't think there'd be a lot of torque between the 2. My "weakest" looking glue attempt has held strong throughout testing (motor #2), but after 3 attempts on motor#1 it keeps just twisting out from under the glue. I'll do some searching on other methods - I've seen just tubing used though so I don't understand why this is being iffy.

    Second problem may have to do with my attempts at adjustment in the arduino. At first motor #3 was relatively unresponsive. Discovered the pin 5/6 on the IBT wire had let go, so that seemed like an obvious fix. After soldering, I thought maybe the motor was in the clipped portion of the feedback, so I bumped it trying to get back to a normal position - and bumped it the wrong way. This made it hit my potentiometer mount and dislodge it, so some work there. Then when I went to fire it all up again and re-test, when I loaded SMCutil, motor #3 just started oscillating in place, and either the IBT or Arduino is "beeping" constantly. I turned everything off and inspected over all of the wiring again and couldn't find an issue. Has anyone run into this?

    I feel so close..... but so far away....
    Jonota, Nov 14, 2023
    #21
  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Ratings:
    +10,902 / 54 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    It is a good idea to use a flexible coupling between the motor and pot, see the FAQs here: https://www.xsimulator.net/community/faq/how-to-connect-protect-a-potentiometer.13/

    Can you please post pictures of all of your current settings.

    With the oscillation have you tried adding some Dead Zone in the SMC3 settings. You can also try swapping the IBTs around and see if the problem follows, if it does the IBT is likely the culprit.
    noorbeast, Nov 14, 2023
    #22
  3. Jonota

    Jonota Semi-jack of all trades, master of pun

    Joined:
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    Occupation:
    Nuclear
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    Kansas
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    95Coins
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    +3 / 0 / -0
    My Motion Simulator:
    3DOF
    upload_2023-11-13_18-13-1.png
    I have no tried to edit any SMC3 settings.
    Jonota, Nov 14, 2023
    #23
  4. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    148,565Coins
    Ratings:
    +10,902 / 54 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    PWMmax is not set, these are the initial setup steps, please see 9: https://www.xsimulator.net/communit...3dof-motor-driver-and-windows-utilities.4957/
    1. Disconnect the motor power supply
    2. Make sure Simtools is not running – we’re not ready for that yet!
    3. Wire up the Arduino (with SMC3 installed) to your H-Bridges and connect to your computer via USB
    4. Run the Windows SMC3 Utility software and make sure it communicates with the Arduino (There is no need to set baud rates, they are not configurable)
    5. Set the Kp, Ki, Kd, PWMmin, PWMmax, PWMrev to 0 for ALL motors (This will make sure the motors don’t move)
    6. Set Clip to 255 (you need to do this first) and Limit to 255 (This will give you plenty of margin if something goes wrong while setting up)
    7. Turn on the power to your motors – nothing should move at this stage!
    8. Set Kp to about 400
    9. Now slowly, increase PWMmax… at some point the motor should start to move. When it does check the “Green” feedback line is moving toward the “Blue” target position.
      • If it is then that motor and feedback is wired correctly - proceed to test other motors.
      • If it is moving away turn off motor power immediately (or quickly reduce PWMmax again). In this case you need to either reverse the wires to the motor being tested –OR– reverse the +5V and GND wires to your feedback pot for the motor being tested (do not do both). Restart the test from the beginning.
    10. Do the above for each motor
    noorbeast, Nov 14, 2023
    #24
  5. Jonota

    Jonota Semi-jack of all trades, master of pun

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    15
    Occupation:
    Nuclear
    Location:
    Kansas
    Balance:
    95Coins
    Ratings:
    +3 / 0 / -0
    My Motion Simulator:
    3DOF
    Yes, that is what I've done. Motor #2 worked perfectly. Now as soon as I connect the USB #3 oscillates and I have the beeping noise. I turned the PWMmax back down so I didn't get any movement. Both motor #1 and 2 started to move around 46, motor #3 around 50.
    Jonota, Nov 14, 2023
    #25
  6. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Joined:
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    Balance:
    148,565Coins
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    +10,902 / 54 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    That may be a hardware fault, as I suggested you can swap IBTs around to confirm.
    noorbeast, Nov 14, 2023
    #26
  7. 90kgOver300m

    90kgOver300m Member

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    Does it only oscillate when mechanically connected to the pot? Could potentially be a bit of backlash or flex / movement causing the pot value to change slightly.

    Maybe try disconnect the pot, and turn the pot by hand until the motor stops and see if the oscillation also goes.
    90kgOver300m, Nov 14, 2023
    #27
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