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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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    My Motion Simulator:
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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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  9. pooh

    pooh Member

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    Update :)

    @Erik Middeldorp you were unfortunately right :) upper mount was bending and finally broke - fortunately in my bare hands when trying to bend it back :)
    i've redesigned it a bit but was kind of limited because of the hole pattern already drilled so i've bought the biggest bearing i could in the same enclosure which is 17mm in diameter. then took outdoor door mounts that are 20mm and cut it down to 17mm (thread basically). it should withstand WW3 now...
    bottom ones are good because there is no almost 90deg angle so the force goes differently.

    IMG_1170.jpg IMG_1171.jpg IMG_1173.jpg IMG_1174.jpg IMG_1175.jpg IMG_1176.jpg IMG_1177.jpg IMG_1178.jpg IMG_1179.jpg
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  10. pooh

    pooh Member

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    and on top of that i have another update - silencing of actuators.
    it's a 2mm bituminous mat and then 6mm foam type mat. it's mainly used when silencing cars / doing car audio.




    IMG_1478.jpg IMG_1479.jpg IMG_1480.jpg IMG_1481.jpg IMG_1483.jpg
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  11. Dirty

    Dirty Well-Known Member Gold Contributor

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    Ha,.... I saw (heard) exactly this type of sound deadening on @PeterW 's actuators two weeks ago :) Or rather,... I DIDN'T hear it, because his actuators were crazy silent. Using Alu-Butyl (or similar material) really helps with silencing those actuators. I am trying to incorporate it into the inside of my new actuator design, but space contraints might prohibit that in the end.
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  12. pooh

    pooh Member

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    Wickie did that inside this pipe (shaft) that moves - and this is something that i will not be able to do and that actually makes 50% of the noise. in my case it is mainly due to the fact that my pipe is like 3mm thick only...
    but my plan for that is to buy bike/cross rubber lag covers and that will silence it to some extent as well as provide some dust covering. no to mention aesthetics ;)
  13. Justin_2

    Justin_2 New Member

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    Hello! Fantastic built!
    I just registered because I want to build a Motion Sim soon too. I Have some kind of different requirements than your project I guess, and I am still looking for the right concept. So to find it, I interested for instance how much weight such a system like yours would be able to carry?
  14. pooh

    pooh Member

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    sorry for late reply... i have no idea but my best guess is that upper part weights around 50kg plus me 100kg so 150kg and it moves without any issues. should be able to handle much more but universal joints are the weakest part probably and would need to be strengthen for that purpose...
  15. pooh

    pooh Member

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    My Motion Simulator:
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    and since i'm already here, one of recent videos:

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  16. Kenshiro27

    Kenshiro27 Active Member

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    My Motion Simulator:
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    Really very impressive
    very nice job:thumbs
    a bit cumbersome all the same but when you love you don't count