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DIY G-Seat

Discussion in 'DIY Motion Simulator Projects' started by early_m, Feb 23, 2017.

  1. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    Due to lack of space I could never afford the luxury of a full size simulator. But I still wanted to experiment and started producing a mini build using servos - just for fun https://www.xsimulator.net/community/threads/2dof-mini-arduino-motion-platform-protoype.9739/

    I've learnt so much from doing a mini version, one of which is that high torque servos can be used to make a 'g-seat'. The idea popped into my head that I could design a g-seat that fitted onto my existing office chair - I could at last experience some motion!

    So over the last week I have built a proof of concept. It's not perfect, and an improved slimline V2 is already in the works. But what it did do was prove to me that a g-seat can give a great sense of motion - especially in VR - and is a brilliant alternative to a motion sim.

    I'm no where near finished, but I am going to try and cover everything that I did and discovered as, while these forums are superb, I sometimes struggled to find the information I was looking for.

    More to come...
  2. Ads Master

    Ads Master

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  3. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    I've currently only made the back section, so can estimate that the total price will be a bit more than double (planning on using 4 servos for the bottom plates)

    GSEAT Parts/Price List

    12mm 607x1220 MDF (could be thinner but screw length an issue) £10.69
    4x Butt Hinges £7.38
    2x 90 degree timbre joining plates £2.99
    Assembly Joints £0.69
    Screws £0.59
    2x SM-S8330M Servo 30kg / 0.22sec £32.00
    2x M3 33-43mm track rod £8.99
    M3 machine srews £2.68
    [Sintron] UNO R3 ATMEGA328P (Arduino Uno clone) £7.95
    L293D Motor Drive Shield for Arduino UNO (only used for ease of connectors) £5.95
    9V 2.5A Mains Power Supply £19.99
    Hobbywing Switch Mode UBEC 6V 5A £5.25
    USB 1m Extension £1.39
    4x 1m servo extension cables £6.40
    Terminal blocks £0.50

    Total £113.44
  4. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    The built frame

    IMG_3021.JPG
  5. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    Some weight saving

    FullSizeRender.jpg
    IMG_3023.JPG

    I plan to do the same to the back plate (and cut off excess material)
    • Like Like x 1
  6. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    Video of first test

    • Like Like x 11
    • Winner Winner x 3
  7. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    Nice one, that has come together really well.

    How does it go under load with you sitting in it, with the 2 X 30kg servos driving it?
  8. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    Absolutely fine, before I bought them I put some scales behind me and forced myself back as hard as I could and only mangaed to get it up to 10kgs - so plenty of room left. Im hoping 2 on each side for the base will be ok. Im 70kgs so should be fine. Running at 6V the speed is also good

    EDIT: I now understand I got this totally wrong. For anyone else who is unsure, 30kg doesnt mean it can lift 30kg. It is torque in kgcm. To work out what it can lift you need to use moments to calculate the force at the lever length you're using

    30kg.cm means the servo can lift 30kg with a 1 cm lever, 15kg with a 2 cm lever, etc.
    • Like Like x 1
    • Useful Useful x 1
    Last edited: Mar 18, 2017
  9. RacingMat

    RacingMat Well-Known Member Gold Contributor

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    My Motion Simulator:
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    well done!
    like @noorbeast said, it'd be interesting to see how it behaves under your weight :)
  10. early_m

    early_m Active Member

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    My Motion Simulator:
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    Thanks, currently the back plates have no problem moving me and I'm 70kg. But it would be very easy to add a second to each side if required. Im going to initially try 2 under each leg in the base. Will update with my findings as soon as Ive had time to build it
    • Like Like x 1
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    Last edited: Feb 24, 2017
  11. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    Made some progress over the weekend. Put version 2 together which is lower profile allowing me to sit further back in my seat

    image.jpeg

    image.jpeg

    Also narrower and much lighter
    Last edited: Feb 26, 2017
  12. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    Also made a 'control box' to keep everything nice and tidy

    image.jpeg

    Servo wires and ard usb port

    image.jpeg

    Power in and switch (for servo supply)

    image.jpeg
    • Like Like x 4
  13. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    The servos are able to move me but they make a groaning noise and vibrate minutely under load. Is this 'jitter'? And does it mean I'd be best off adding a second servo to each side?
  14. RacingMat

    RacingMat Well-Known Member Gold Contributor

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    Um, that's not a good news...
    Groaning noise is a small amplitude jitter, yes. But jitter can be with high amplitude (like if the PID is not well tuned).

    You can reduce the length of the lever and hear if the motor is less stressed
    or add a second servo
    • Like Like x 1
  15. early_m

    early_m Active Member

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    My Motion Simulator:
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    I assumed it was stress related, so thanks for confirming. I am running a 30mm lever so will try adding a second set of servos to see if that resolves the issue. If not, reduce the lever length as suggested
  16. early_m

    early_m Active Member

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    My Motion Simulator:
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    Another concept - will call this V3! V2 gave a good sense of G in the corners, but want more down the side of my body. Have come up with this design - anyone see any issues with it? Shouldn't be any load on the side panels so have gone with HK15328A servos (12.8kg/cm)



    Should hopefully get some time over the weekend to put it together and test
    • Like Like x 2
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  17. RacingMat

    RacingMat Well-Known Member Gold Contributor

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    My Motion Simulator:
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    very nicely drawn!
    but it will be very hard to setup because movements will combine and mix...

    you may consider a V4 with side panels independant from back panel ;)
  18. early_m

    early_m Active Member

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    My Motion Simulator:
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    I think I can make this way work, and I'm trying to keep it compact as possible. Will give it a go and report back as will only cost a sheet of mdf

    And im sure it wont be long till we're on version 20
    Last edited: Mar 2, 2017
  19. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    Version 3.0

    image.jpeg

    The back paddles now have 2 servos each. One was enough to apply pressure but jitter sometimes occurred. Being so cheap adding a second was a no brainer. They deal with Surge, Sway and a little Pitch.

    I have also added side paddles to apply pressure down the side of the body. This simulates lateral G force (Sway) much more effectively than back paddles alone. It really feels like you're being pushed into the sides of the seat when cornering. I didnt think the servos would need much torque but for realistic pressure they need to be quite high torque. My current ones are about 13kgcm and struggle a little so will source another.

    In total there are 3 Axis. I'm using @eaorobbie 's RC code, modified to include an additional servo.

    Lastly I will add some padding to make a little more comfortable.

    Next step is to put together the base which will simulate surge(breaking), heave and sway. I plan on using 3 30kgcm servos under each leg (6 in total).

    Also needed more power so have put together a new power/control box giving 6VDC 20A output

    image.jpeg
    • Like Like x 2
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    Last edited: Mar 16, 2017
  20. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    Video (sorry for the low res, filmed using front facing camera)

    • Like Like x 4
  21. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
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    • Like Like x 2
    Last edited: Mar 17, 2017