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Senior Project: 2DoF Motion Sim!

Discussion in 'DIY Motion Simulator Projects' started by S.N., Nov 4, 2018.

  1. S.N.

    S.N. New Member

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    Hi everyone!

    I’m super excited to be building my first sim at long last! :)

    Last summer, I thought I could save up a few hundred dollars and build a sim in my spare time, but I got too busy and couldn’t even decide between seat shaker or a Joyrider. I was short on money, time, and knowledge. But, I recently proposed building a 2DoF sim for my senior thesis project, and my proposal was approved by the Mechanical & Aerospace Engineering Department and I’ve been granted a little over $1K to work with! :D So, now, I’ve got the money, the time (2 semesters) and resources to make this dream happen! I’m so excited to get started!

    A little bit about my sim idea: I’m pretty set on designing a simple seat shaker with a welded rectangular steel frame (I want to learn how to weld and will be taking lessons from the instructor in our machine shop). My only concern about steel is weight/modularity (in case I need to lug my sim across campus), but I think I can design around this and enjoy the ease of welding steel (as compared to aluminum).

    However, I’m very new to sim design and really designing/machining in general, so I have a few questions as pick my materials and create a design:
    + Any recommendations for the seat - my main concerns here are ease of attachment to base and cost (aiming for ~$100 if possible)
    + I am consider cutting this in half to get a cheap universal joint (and a backup one too!)
    amazon.com/XMT-MOTO-TRX500-2005-2009-TRX680-2008-2009/dp/B07CVXXBYD
    Any thoughts?
    + I have been working on the base (it's my first design using rectangular tubing, so modeling it in Creo was a bit of a challenge, so don't judge too harshly :p). Below is a picture of it, and a link to my Creo .prt and the exported .obj file of the design. All units are inches and are set as parameters in Creo, so it should be easy to modify any dimension with a few clicks. Any feedback you have regarding the base's design would be incredibly helpful!

    [​IMG]
    Link to .prt and .obj Files: https://drive.google.com/drive/folders/1q2vG8CEGec-C24d9xtN_APEOmm2RrIu-?usp=sharing

    Thank you in advance for your help with my senior project. The DIY motion simulator community is fantastic!

    Can't wait to make my own! :D

    Sincerely,
    Larry


  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    Getting an old tailshaft from a wreckers and cutting off and using the universal joint is an even cheaper way to go.
    • Like Like x 1
  3. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
    AC motor, Motion platform
    All the best for your Senior Engineering Project. Recommend you start your research in the 'FAQ'.
    • Like Like x 1
    • Agree Agree x 1
  4. S.N.

    S.N. New Member

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    Thanks, noorbeast and SeatTime for your quick responses! :)

    I will definitely keep my eyes out for parts I can source from labs/shops on campus, but unfortunately I don't have a car so it might be hard to visit junkyards. That said, I do have over $1K in my budget, so as long as I'm reasonably careful with it, I should not have a problem (I hope). I guess I should have been more clear in my original question: do you think the shaft I found on Amazon would suffice?

    I've been looking around online for a good racing seat for around $100 and I've been having a tough time finding one outside of eBay/Craiglist. Any recommendations for brand, website, or what to look for?

    Lastly, any thoughts on my base's design? Do you think the proportions/shape are reasonable?

    Thank you again for your help!

    I will be sure to continue to read the FAQ posts in my spare time - they are pretty helpful!

    Sincerely,
    Larry
  5. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    Personally I consider a traditional uni joint is best for a 2DOF rig, as there is no lateral twist and the flat flange makes it easy to mount to a seat.

    The dimensional design leverage matters more at this stage than the shape of the frame, use SimCalc to get an idea of the physics and movement of your design: https://www.xsimulator.net/communit...e-linear-speed-and-forces-of-your-design.270/

    You should look at a harness when checking out seats, as a harness helps convey the motion cues and can itself be motion driven.
  6. S.N.

    S.N. New Member

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    Hi, everyone!

    Sorry it has been so long since my last post. My previous semester was quite busy, but now I have a few weeks where I will be able to focus primarily on my build.

    A few updates:
    - The frame is cut and I just need to solder the last few pieces onto it
    - The motors have been tested using the JRK 18v27 and work using a simple potentiometer.
    - My Hall Effect position sensors have just arrived - I will test them shortly
    - I have the seat, harness, bracket to attach the seat to the base, etc.

    What still needs creating:
    - The frame and seat need to be connected to each other using my universal joint
    - I need to select and order parts to make my crank arm and shaft for the motors to control the seat (so, I should make a CAD design for my whole sim to figure this out)
    - Eventually, I need to get simtools running with my controllers

    TL;DR there's a whole lot left to do in April, but I am finding more and more time to devote to the project :) Excited to be making a simulator! :D

    -Larry

    PS: I will post some photos in a reply to this post shorrly
  7. S.N.

    S.N. New Member

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    Yes, I did screw up cutting the diagonal pieces, and my welding will need some touch-up, but overall, it's getting there…

    Attached Files:

    • Like Like x 1
  8. S.N.

    S.N. New Member

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    Another update as the deadline looms nearer...

    I now have modeled the full assembly in Creo and you can see how the chair will respond as the motors move in the attached photos.

    I also have finished machining ALL components for the project at long last, and now it's just a matter of screwing and bolting it all together :) Some pictures are attached.

    My goal today and tomorrow is to get it assembled and play around with SimTools (I still need to download that program plus a game or two...). Also, my computer for the project currently is not the best for gaming so if anyone has recommendations for low-quality free racing games just to test out SimTools and my build before I eventually get a new computer, it would be greatly appreciated! :)

    Thanks!

    Attached Files:

  9. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    The demo version of Live For Speed works fine for testing and the plugin for it is included in SimTools specifically for testing purposes.
    • Like Like x 1
  10. S.N.

    S.N. New Member

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    Thanks - I just tested it to make sure all programs installed and ran successfully and it is good so far…

    Now to get the electronics done and test the whole system together (manually first, then with a game). :)
    • Like Like x 1
  11. S.N.

    S.N. New Member

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    Ok. My build is finished and has been tested. I'll send some photos and drawings soon. It's not the best, and if I could do it again, I'd definitely make some changes but it works well enough and after some tuning and a bit of welding to strengthen a few connections, it will be perfect! :) So excited!!
  12. S.N.

    S.N. New Member

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    Here are some photos of different parts of the build + an overview of the simulator. I'll be taking it apart soon to paint it black and then reassembling it stronger and wiser ;)

    I've also included the drawings for machining the motor/gearbox mounting plates, base frame, seat frame, and lever arms, as well as a MATLAB script that can send commands to the JRK to test and plot things like sinusoidal tracking of different frequencies, step functions, etc. It's another tool to use to test PID coefficients.

    Thank you all for your help. (sorry for posting so infrequently!) Feel free to ask any questions you have - I'd love to share my first sim-building experience :)

    Attached Files:

    • Like Like x 1