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My 2dof project for $200 and NO welding (+$100 for Traction Loss + $200 for G-seat)

Discussion in 'DIY Motion Simulator Projects' started by Qlittles, Sep 27, 2017.

  1. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    There is always the possibility of a runaway motor, if something goes wrong.

    Hall sensors can fully rotate without breaking, these would work and are available via element14 sites worldwide: http://au.element14.com/bi-technolo...fs/sensor-hall-0-2v-20v-to-10v-pin/dp/2319662
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  2. Qlittles

    Qlittles Active Member

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    Ah, the cost of $33 will break my budget ceiling -- but it looks like the perfect solution. Are there cheaper hall pots around the price of $10?
    Last edited: Oct 31, 2017
  3. Qlittles

    Qlittles Active Member

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    Oh no.... I finally got around to testing out the wiper motors. They work, but for some reason, they sound pretty loud... oh well ... I'll still use them. (I'd advise against getting the volvo s40 wiper motors)
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  4. armpit

    armpit Active Member

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    Did you test them with straight 12v or was the testing through the motor controllers?
    If it's through the controller there are various things you can do with the PWM frequency or update rates to reduce the 'electrical noise'. (if you are using the SMC3 code, look into increasing the Fpid value and reducing the Kd value to zero for testing)
    If it was with just straight 12v you could try opening them up to add a little extra grease in the worm gearbox which will reduce mechanical noise.

    Or like you said, just use them anyway. Are you married? ;)
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  5. Qlittles

    Qlittles Active Member

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    Haha, yes, I am married, and the sim chair is actually set up in my bedroom for the lack of space. I'll be racing at very specific and limited times.

    I was testing the motors with straight 12v. I had opened the gears and there were plenty of grease on them, and I also tried running it without the top, as there were some metal leads that touch the gear wheel from the top... but the sound seems either to be the motor itself or the gears.

    But wow, I didn't think what you mentioned about changing the output was even possible. I'm a bit mind-blown, as I don't know much about electric circuits in general. A possible solution or a way to mitigate the problem may exist thanks to your help :) I'm really appreciating this forum because of such helpful members!
  6. Qlittles

    Qlittles Active Member

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    Next, I prepared the motors for the pot.

    Here is the motor opened
    20171027_112240.jpg
    Close up of the cover
    20171027_112246.jpg
    I drilled a hole in the middle
    20171027_112824.jpg
    I put the cover back on and drilled in the center using a thin metal drill. I drilled maybe 1/2 centimeter, then put a screw in with super glue at the tip.
    20171027_163935.jpg
    It feels secure enough, and when I rotate the arm, it spins freely.
    That's all for today
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  7. Qlittles

    Qlittles Active Member

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    My Motion Simulator:
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    Next, I attached wooden blocks to the motor to keep it secure.

    Here is one side
    20171027_164013.jpg
    And here is a pic from the other side
    20171027_163959.jpg
    The bottom side of the square metal piece is flush to the ground so that the majority of the weight transfers directly to the platform rather than through the wooden blocks. I thought about buying some metal L bars, but went the cheaper wood route...
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  8. Qlittles

    Qlittles Active Member

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    Next, I mounted the wiper motors to the base platform.
    20171027_194421.jpg
    the little wooden piece is screwed down from the top, but the other bigger block is screwed from the bottom with a long wood-nail
    zoomed out to show all the motors
    20171027_194427.jpg
    the seat is placed on the platform for the final time (I hope)
    20171027_171409.jpg
    that's all for today!
  9. Qlittles

    Qlittles Active Member

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    Here is some more work done

    I put the heim joint on the motor arm
    20171031_113829.jpg
    The heim joint has a 5/8 inch openings, which i thought was thick enough for my application.
    However, since the biggest drill i had was 1/4, i put a 1/4 bolt through the arm and the heim joint, and filled in the gap with JB Weld (I did the same for the traction loss motor arm).
    A little messy, but snug and tight.
    Here is the arm attached to the seat frame
    20171031_141422.jpg
    I ran into a problem when I sat on the chair after -- the chair would wobble vertically about an inch on the left and right side. I noticed that the seat frame would wobble because the frame towards the feet is attached to the seat frame with only a knob (so, it's not a solid one piece). Here is where it wobbles:
    Inked20171027_171409_LI.jpg
    The solution? I think I will put some aluminum metal bars to enforce the frame where the motor arm attaches to it (I thought about moving the wiper motors to the back of the base and attaching it to the back of the seat frame... but there is no space because of the traction loss motor).
    Oh man, I think if I had to do it again, I would put the wiper motors on the back and have them attached to the seat frame itself.
    This mistake sets me back $10 (for the aluminum metal bar).
  10. Qlittles

    Qlittles Active Member

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    Next I installed aluminum support bars
    20171101_221656.jpg
    After I installed the bars, the wobbling from the seat frame stopped. However, I noticed that the base frame would wobble where the wiper motors were. I think this happened because the base was made out of wood, and because the only thing supporting it was the center caster wheel (modified). As a solution, I bought 2 wheels to place under the wiper motors so that the weight would go directly to the floor.
    20171102_182758.jpg
    Once again, I think if I put the wiper motors on the back, I would not have run into this problem (or alternatively, if I went just 2dof and not traction loss).

    Well, since I bought the aluminum bar, and also ordered a seat belt ($5), the price for 2dof has gone up to $204.
    Also, since I had to buy the extra wheels ($7) for traction loss, my spending for traction loss is now $97.

    I hope I don't have to spend any more $$
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    Last edited: Nov 6, 2017
  11. Qlittles

    Qlittles Active Member

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    next, i attached heatsinks to moto-monster boards.
    i thought about buying the heatsinks and either use double sided thermal tape, or buy heatsinks with thermal tape on them, but looking online, they would cost at least $8.
    since i am $1 over the total budget, i opted to go the "free" route and took apart a broken PSU, took out the PSU heatsink, and sawed it down to 3 pieces.
    i had to position the moto-monster vertically since the heatsink is vertical.
    20171103_125936.jpg
    this is a sandwich of wood, lego, moto-monter board, thermal paste (which i already had), heatsink, and CPU heatsink holder.
    this took me a while to put together, but it feels secure, and the heatsink is bigger than what i could find for cheap online.
    here are the other 2 moto-monster boards
    20171103_175150.jpg
    the one with the larger heatsink is the moto-monster board that will control the wheelchair motor.
    here they are in 1 pic
    20171103_175208.jpg
    this will be placed under the top case of the PSU that holds the fan. good thing i kept the broken PSU instead of throwing it away!
    it's a Frankenstein, but i need to test it to see if it is alive :)
    next is wiring.
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  12. Qlittles

    Qlittles Active Member

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    i'm looking at the wiring, and it looks like i can combine these 2 wiring diagrams for my 3 half moto-boards and 1 arduino
    dual uno.png SMC3_3DOF_online.jpg
    upon closer inspection, the wires are placed in differently between the 2 diagrams... i'm assuming that the wiring doesn't need to be exact?
    ok, now i'm going into the "unknown" territory of electronics and programming.
    there is a reason why i put this part off until now -- i just don't know what to do, and i'm feeling my way in the dark.
    for example, i have 3 motors... is there arduino code for 3 motors? i found one for 3dof, but mine is 2dof + traction loss. does it make any difference for arduino since simtools will control the motors? if i need to get the code for 2dof + traction loss specifically, where would i find it? or would i have to learn coding for arduino?
    help would be greatly appreciated!
  13. llluis

    llluis Active Member Gold Contributor

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  14. Qlittles

    Qlittles Active Member

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    Wow, what a quick response! Thank you mucho for pointing me in the right direction -- i will check it out tonight and see how far i can get on my own :)
  15. llluis

    llluis Active Member Gold Contributor

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    All the info you need is in the first page. Keep us posted.
    Your connection will be very similar to your first image, just pay attention to the right wires at the arduino.
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  16. Qlittles

    Qlittles Active Member

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    thank you !
  17. Qlittles

    Qlittles Active Member

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    ok, i got as far as tinkering with SMC3 Utils.

    MOTOR1
    I can successfully move MOTOR1, both clockwise and counter-clockwise. No problems.

    MOTOR2
    As with motor1, I can move the motor, but clockwise turns REALLY slowly and at times not at all. Counter-clockwise moves without problems. I did notice that when I was trying to turn it using a wrench, clockwise was almost impossible to turn... does this mean that some kind of braking is in effect? it's weird because it's the exact same model as motor1... do i need to buy another motor?

    MOTOR3
    The graph and behavior on SMC3 Util looks perfect. When I turn the pot, the green graph goes up or down, and the yellow graph goes down when I hit the blue line. HOWEVER, the actual motor does nothing.... this is weird, and even more weird because one time, I turned on the UNO, then turned on the motors, and it worked or about 15 seconds then stopped. I cannot duplicate this phenomenon no matter what I do with SMC3 Util. I might have thought that something was wrong with the wiring if it never moved... but it DID move... hmmmmm
  18. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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  19. Qlittles

    Qlittles Active Member

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    Thank you Noorbeast! The speed fix looks like a viable option to try, though I don't know if I have all the tools to get different parts of the motor off.

    I think you are right about the grounding (though I'm not sure yet). I say this because:

    1. When I turn off the wiper motors and only turn on the power supply for motor3, the wheelchair motor works. However, it runs at full-speed even when all the values are 0 on the sm3 utility.
    2. When I turn on the wiper motor power supply, motor3 does nothing.
    3. When I did have it work that one time, I think it was a weird combination of something like motor2 off and motor1 in a certain configuration. When I stopped motor1, motor3 stopped as well.

    What I deduce from this is that either
    1. Somehow the wiper motor casing is coming in contact with something (so, the isolation problem). I think this is the most likely scenario, although I did due diligence to isolate the motors by using a wooden frame. Wood was not conductive last time I checked...
    2. I messed up on the wiring.

    I think when I get home today, I'll try disconnecting the wiper motors altogether and just to run motor3 (wheelchair motor) with its own power supply to see if it works normally. Depending on what happens, I might try moving motor3 with motor1's setup. I'll also try direct 12v to the motor that doesn't spin counterclockwise well.

    I hope I can identify the problem, and hopefully, the solution won't be too difficult.
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  20. armpit

    armpit Active Member

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    The way you describe this issue matches exactly what happened to me when I had a motor controller with an internal short (3 out of 4 single chip controllers like you're using that I tried had this issue, I was able to refund them). Forward would work fine, reverse was very slow and over the course of 10 seconds or so would slow to a crawl or even stop. The heatsink would be extremely hot to the touch after that compared to the same amount of time going in the forward direction.
    Have you tried using the known-good motor controller for MOTOR1 with MOTOR2 wired into it instead just for testing?
    Electrical gremlins are so frustrating!
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