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Question My 3DOF motion simulator

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Cameron Olson, Mar 30, 2021.

  1. Cameron Olson

    Cameron Olson Member Gold Contributor

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    My Motion Simulator:
    3DOF, DC motor, Arduino, Motion platform
    Hey all! I purchased a motion simulator off another forum user here. (See previous build thread https://www.xsimulator.net/community/threads/my-3dof-motion-simulator.14908/ ) I got it all wired up and working in SMC3 utility. Clip and limit set to 225 and Kp 400. Moved PWMmax so green,blue and gray lines all match up. Using manual settings on the left and moving the blue line all motors move as intended. Am I ready to move to simtools and start testing? Do I keep those settings the same in SMC3 while testing in simtools? Currently waiting on new crank arms to arrive because the ones that were originally fabricated for this project were too long and blew out a motor. Can I do some test without the top platform attached while I wait? Thanks!

    Pic of bottom platform with motors attached and wired.
    [​IMG]
    Top platform
    [​IMG]

    Attached Files:

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  3. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    Yes you can start testing in SimTools once SMC3 is properly configured and working as expected and yes you can do initial testing without the top frame attached.

    SMC3 sets the Arduino configuration, once that is done shut it down and don't run SMC3 at the same time as SimTools, as that will cause a port conflict.

    Gab a copy of the SimTools manual and keep it handy for reference: https://www.xsimulator.net/community/faq/rtfm-start-with-the-official-simtools-documentation.117/

    See the tips here on how to refine a motion profile, though you won't be able to fully do that until you can attach the top frame: https://www.xsimulator.net/community/faq/steps-to-create-a-motion-profile.228/

    This is how to configure the interface settings in SimTools for your 3DOF:

    [​IMG]
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  4. Cameron Olson

    Cameron Olson Member Gold Contributor

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    My Motion Simulator:
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    Awesome thanks for the confirmation on that. Those were the settings I had in simhub as well so looks like I'm on the right track
  5. Cameron Olson

    Cameron Olson Member Gold Contributor

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    My Motion Simulator:
    3DOF, DC motor, Arduino, Motion platform
    I'm having a lot of trouble with simtools output testing. No matter what I do my motors won't move. I must be missing some small detail. I followed the guide/documentation above and nothing.

    Interface settings are good.
    [​IMG]

    Did a run on Dirt Rally 2 and recorded then modded the min/maxs
    [​IMG]
    Testing 1 axis at a time but when I turn on DOF output the game selected in the tuning center automatically switches to default and very high values appear

    [​IMG]

    What the hell am I doing wrong. About to pull my hair out. Just spent 6 out trying everything. Reading documentation, forum posts, searching YouTube for setup videos and still no progress. Xsimulator you're my only hope...:sos

    Attached Files:

  6. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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  7. Cameron Olson

    Cameron Olson Member Gold Contributor

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    WOW this is what I get for pulling an all nighter working on my sim rig... I forgot to plug in the motors... my brain is fried but making progress lol. Think ill take a break from the computer and start sketching out yaw and monitor mount fabrication design ideas. Thanks for the quick replies though. You guys rock!
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  8. Cameron Olson

    Cameron Olson Member Gold Contributor

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    My Motion Simulator:
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    Is there a version on that example with 3 motors in a triangle shape like my rig? Wont some motions like pitch use all 3 motors while tilt will use 2?
  9. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    Sway and roll will use 2.

    But once set in practice SimTools mixes axis on the fly, so for example roll in practice tends to have other related movement such as heave and pitch mixed in, like running over a curb, pitch up then roll, likely some heave for bumps, then pitch down as you run off the curb. If done while cornering there will also be sway leaning away from the corner.

    You initially set the axis as SimTools expects: https://www.xsimulator.net/community/faq/which-way-to-set-simtool-axis-movements.230/

    Then tune each axis individually, then turn them all on and complete refinement tweaks: https://www.xsimulator.net/community/faq/steps-to-create-a-motion-profile.228/
  10. Cameron Olson

    Cameron Olson Member Gold Contributor

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    My Motion Simulator:
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    Got a default profile setup and working in Dirt Rally 2.0 is the a way so I can increase the range of movement? So the starting position of the cranks would point and the ground and rotate around 160-170° to their max height pointing up?
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  11. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    The effective use of torque for a leaver is most effective at 90 degrees and falls off rapidly at anything over about 38-40 degrees up and down, anything over that puts lots of additional strain on the motors.

    Think of it like pushing a heavy door open, at 90 degrees you could do it with your little finger, once you get 40 degrees over that the effective force is greatly reduced, as you start to push more toward the hinge of the door than the direction you want to open it.

    SMC3 is used to set the range, with the Max and Clip limits.
  12. Cameron Olson

    Cameron Olson Member Gold Contributor

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    I get that. That why I ordered shorter cranks they will be 70mm max from center. At 70mm the theoretical calculated weight the 3 motors will be able to lift is 750lbs the top platform + chair + devices + monitor + my weight is less than half that. Hypothetically what would the max and clip limits to achieve 280 degrees rotation?
  13. Cameron Olson

    Cameron Olson Member Gold Contributor

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    My Motion Simulator:
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    I attached a wooden platform to the top to better assess the motion. Looks surprisingly smooth without having done any fine tuning yet.

    (Edit: surge axis has been reversed since filming this)
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    Last edited: Apr 1, 2021
  14. Cameron Olson

    Cameron Olson Member Gold Contributor

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    My Motion Simulator:
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    Still waiting on the new motor cranks so I've been working on the upper part of the platform. Got the pedal mount and monitor mount welded on. Still need to add a support beam that attaches to the frame from the back of the monitor mount and mounts for my sequential shifter and ebreak but getting pretty close.

    20210411_210623.jpg

    20210411_210652.jpg
    20210411_210848.jpg
    20210411_210933.jpg
    20210411_210816.jpg
    20210411_210552.jpg
    20210411_210350.jpg
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  15. Cameron Olson

    Cameron Olson Member Gold Contributor

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    We moving boys!


    I do have one issue. From the perspective of the video the front right motor is running really hot. The others a fine. I have reset the starting position so the crank pointing up just a hair to hopefully reduce torque on the motor. Any other ideas on how to alleviate this issue?

    (Edit: the motor on the opposite side was overheating before and I applied the same technique. That one runs cool but still having issues with the other motor)
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  16. Cameron Olson

    Cameron Olson Member Gold Contributor

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    Tilting the cranks up and really tightening the screws seems to have fixed the heat issues. Any suggestions/feedback on tuning based on the last 2 videos?
  17. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    Nice job :thumbs

    In terms of feedback heave and surge seem either very limited or are not configured, there should be plenty of both for DR2.
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  18. Cameron Olson

    Cameron Olson Member Gold Contributor

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    Thanks! Feels great to finally get it running and actually sit in it. I turned down sturge because that seemed to aggregate the overheating issue. Now that that's fix ill turn it back up. Also have heave set pretty low. Will mess around with that. Thanks for the suggestions. I don't know if this is allowed but do you know any US based websites to order another motor similar to the ones I have? Time to get working on yaw!
  19. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    Yaw or traction loss, I would have expected the latter.

    Perhaps US based members may have suggestions re locally sourced motor possibilities.
  20. Cameron Olson

    Cameron Olson Member Gold Contributor

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    Yaw? I was planning on doing it with wheels like dof reality does theirs. Now that I'm thinking about it whats the difference between the 2?
  21. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    Yaw pivots around the center, and is particularly important to simulating helicopters, while traction loss pivots somewhere near your feet and is used to simulate the rear end of a car breaking loose, which is common to race sims. They are two different forces.

    With wheels at the back and a pivot point at the front that is traction loss.