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Zen 6DOF Motion Simulator

Discussion in 'DIY Motion Simulator Projects' started by pooh, Apr 27, 2020.

  1. pooh

    pooh Member

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    It is a bit faster this way Thanos however i had buttons speed set to 100...
    Bearing itself is not that loud as you can hear on the video and the ballscrew is even less noisy but aluminum enclosure resonates and the work table itself makes it more noisy. One thing i will need to probably exchange is ball nuts as they have plastic ends and one broke off and around 10 balls were inside enclosure. I've managed to assemble it again - we'll see...






    1E2CB8A4-2C78-45A1-B6FA-1389DEB25D0F.jpeg
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    Last edited: Sep 10, 2020
  2. pooh

    pooh Member

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    Other actuators were working better. Only the one that i had issue with ball screw was giving strange sounds so I've dissassembled it and regreased. It behaves like others now - we'll see for how long...

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  3. pooh

    pooh Member

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    update on upper mounts. as a bonus - it was very easy to include @Dirty's comment about rubber between upper platform and actuators (10 euro washing machine 600x600x8mm rubber pad from Leroy Merlin). lower platform already stays on 15mm rubber pads:

    IMG_8363.jpg

    Attached Files:

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  4. pooh

    pooh Member

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    just when you think it's over...
    i've started moving it by 2 back actuators and i think there's too much play on the joints that makes it quite noisy and shaky...
    take a look (it can be heard rather than seen):


    i already asked my locksmith to manufacture new pins so there is absolutely no play there.

    since i've disassembled it totally i'm thinking about adding this 8mm rubber mat below those bearings that are on the lower platform - should help with silencing as well as some floor shaking.
    @Dirty , what do you think?
  5. Dirty

    Dirty Well-Known Member Gold Contributor

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    I think that so many people got quite acceptable results with using "pins in holes" or cheap(-ish) U-joints without ball bearings, that it is safe to assume that you will too :) I have no hands-on experience with this type of U-joint construction though.

    If I remember correctly, I think @PeterW did make some efforts to get his hands on precision pins for his U-joints and those worked absolutely flawlessly. So much so that I was almost going to abandon my own "integrated-all-ball-bearing-mulitaxis-U-joint" development:
    Rig_COnstruction_2020-Mar-03_01-14-26PM-000_CustomizedView3622226751.png Rig_COnstruction_2020-Mar-03_01-57-17PM-000_CustomizedView18111842447_png.png IMG_0333 2.jpeg
    ...which in the end I didn't, and I am very happy with my choice. :)

    In my opinion a rattle-free platform is very important! And a common misconception is that on a 6DOF rig those joints will be under a constant positive load, which is NOT the case. I'd estimate that, even when using the rig for smooth flying, my joints undergo a load direction change once every few seconds. Probably once a second on more action packed types of operation.

    I did build those super smooth U-joints, but if you can achieve a tight tolerance with pins and holes it should get the job done.

    Cheers,...:)
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  6. pooh

    pooh Member

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    I'm redesigning those pins so theres no play. You can clearly hear and feel it while actuator moves at higher speed so it has to go. Especially at 500mm/s you can expect negative load.
    My question was actually more about this 8mm rubber mat below the bearing block on bottom platform.
  7. pooh

    pooh Member

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    finally an update. beast is alive! it works extremely well - much better than i expected. initially i had some challenges with tuning FlyPT Mover (@pmvcda ) as i started completely from scratch but then i recalled there are some examples added with this soft and so i took @SilentChill 's settings and started with that. it was a blast! i only had to do very little adjustments to suit my needs. There is still one thing i need to explore when it comes to tuning - i think it can be better tuned for traction loss of RWD cars - i feel well when the car grabs traction back but when it looses it initially it could be felt better (more violently so to speak) so it is caught faster by me. i think "how fast we reach this position" can be increased for starters.
    another thing i need to take care of is squeaking of one of the actuators. i believe i know what is causing it - it's the 3d printed rotation blocking piece that moves on those smaller rods inside actuator. it's very small issue (and only acoustic one) and i'm too happy with the performance of the platform to disassemble it now (i play in headphones anyway).
    one observation that i have is that this kind of stroke/speed combination is completely unusable when it comes to F1 cars - it ends up with jerking back and forth caused by too much force being applied to my body so that i unintentionally move my feet from the brake pedal and then apply it again and so it goes... it has to be tuned down for that type of cars :)
    next items are DD wheel (already got TDD from @Thanos and assembled wheel - just need to buy servomotor) and loadcell pedals (for now i 3d printed them and made it using Hall sensors with lots of rubber on brake pedal - they work surprisingly well).

    here are some initial videos:











    https://www.youtube.com/watch?v=iS4dEUSMisA
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    Last edited: Oct 23, 2020
  8. Dirty

    Dirty Well-Known Member Gold Contributor

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    That's even an issue in real life fly-by-wire aircraft and also in older high performance sports cars. It was so common, that it got it's own acronym: PIO. Stands for pilot induced oscillations. You can use a small deadzone on your joystick, but I think that is not an option for a pedal in a car

    The silver bullet for that problem would be...
    1. A flight stick with realistically high forces. I use a stick with almost 100N of force and in real life that can go A LOT higher than that.
    2. Mechanical dampening (all Airbus aircraft)
    3. Software dampening (e.g. F-16)

    Back in the days, the software dampening was actually implemented in DCS.

    Dirty :)
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