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Question DIY 3DOF (actuator) with Traction loss

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Horseweed, Sep 1, 2022.

  1. Horseweed

    Horseweed New Member Gold Contributor

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    Hello, as the title says , I am trying to build an actuator style 3DOF motion platform with traction loss. My plan is to build the Stewart platform on top of another frame with a wiper motor driving my yaw.

    Is there a "turn key" Arduino code that would work for this?

    if not,

    Can I use SMC3 with an Arduino Mega? does SMC3 support 4 motors?
    Also considering Jumping two Arduino Uno's via I/O ports to drive the 4th motor.

    Just looking at my options.

    I currently have 4 IBT_2 motor drivers I plan to use.

    Thanks in advance.
    Last edited: Sep 1, 2022
  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    I am not sure what you actually have in mind, as you mention a 3DOF then in the next sentence a Stewart rig, which is normally understood to be a 6DOF. Without understanding the design more clearly it is hard to determine if a wiper motor would be adequate for yaw, my guess would be that it likely would require a lot of inherent design leverage and may not meet desired sped parameters, but you may have some creative solution so please do explain further.

    SMC3 can handle up to 3 axis and was designed for the Uno, as per its relevant thread, IBT_2 is supported in Mode 2: https://www.xsimulator.net/communit...3dof-motor-driver-and-windows-utilities.4957/
  3. Horseweed

    Horseweed New Member Gold Contributor

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    My plan is to build something like the picture attached. I pulled this image from a google search. the concept I am going for would be similar, however my budget is limited on this project so there will be slight differences.

    But as you can see it will be limited compared to a full 6DOF Stewart platform. Which is why I am wanting to add the extra motor for yaw. My main use for this would be sim racing so I don't mind if there isn't a dramatic amount of yaw. Just enough to feel the tail slide out. I will probably make some sort of leverage linkage to get more range out of it if needed.

    I am still in the brainstorming process of the actual frame, so I am open to ideas. This is why I wanted to be sure it was possible and there was software backing for it before moving forward. I have an extra actuator if needed, but I think this design will be compact, and effective.

    Attached Files:

    Last edited: Sep 1, 2022
  4. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Just a clarification to keep in mind, yaw rotates around a center point and is most prominent in flight based circumstances, traction loss has a pivot point near the feet and is more applicable to sim racing where the rear end breaks lose.


    Personally I think the likes of @SeatTime's 3DOF design if far less subject to torsional twist forces acting directly on the actuators, but as always look forward to others pushing the design envelope.
  5. Horseweed

    Horseweed New Member Gold Contributor

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    Yes, I say yaw only because that is the typical name of the axis, but I plan to use a pivot point on the front in my design. for my upper actuator mounts, I'm going to use heim joints. unfortunately the bottom of the actuator will have to have some sort of wishbone mount so the platform doesn't collapse on itself.

    honestly my setup is super cheap for now. My dogs chewed up my couch and it had 2 29v dc actuator motors rated at 1000N torque. I ordered some 400mm 1605 ball screws and tossed the recliner ballscrew and made a makeshift mount for them. they actually have a pretty decent speed to them. However, this whole project is likely going to be underpowered, and not entirely structurally sound. but if I can get a good foundation, I will make improvements once I see it work!

    I'm setting up my electronics now, and I'm waiting on parts to make DIY hall pots from normal pots seen on a post here. I forget who did it. but that's where i'm at.

    For some reason I can't see SeatTime's page. but I'm interested to see what he's got!
  6. Horseweed

    Horseweed New Member Gold Contributor

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    Here’s my electronics so far. Part of the reason I posted this thread is I am at the point of wiring in all of my signal wires to the Arduino’s. But I’m at a crossroads because I don’t know if i should stick with one UNO, two UNO’s, or put a Mega in there. Haha

    I’m using a thermaltake mini itx pc tower to hold all of my electronics just so it’s tidy.

    Attached Files:

  7. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    @SeatTime's thread is a par excellent journey through DIY motion rig development, touching on most established approaches and also innovatively breaking new ground, so while long it is worth reading chronologically to understand the evolution of motion simulation thinking and creative design possibilities: https://www.xsimulator.net/community/threads/seattimes-sims.11757/
  8. Horseweed

    Horseweed New Member Gold Contributor

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    Hey noorbeast, quick question. I remember reading somewhere that you could combine smc3 arduino’s in sim tools. If I read it right, that means I can run the 3DOF on one board with smc 3 and the TL motor on a separate board with smc3. Is that correct?
  9. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    Yes you can use and configure multiple control boards and axis in Interface Settings.
  10. Horseweed

    Horseweed New Member Gold Contributor

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    Awesome, thank you! I’m getting closer. I’ll post a video when I get it running!
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