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G helmet system starting up. Idea phase and minor Hw building

Discussion in 'DIY Motion Simulator Projects' started by Trigen, Apr 7, 2020.

  1. Trigen

    Trigen Active Member

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    I've decided to start my G helmet system. It will be adjustable for width to easily accommodate either a helmet or fks a pimax HMD. It will most likely use gopro attachments for the sides so its easy to click in and out of and changing gear for VR/triples.

    Here's my train of thought at the moment.

    It uses 8020 profile

    It will have rigid frame that will just fit your head and is adjustable. This way you wont have it dragging the HMD around if you are using that. With a helmet the fit isnt as important. Ive added some extra foam to the DAS on my Pimax.

    It will have either a U joint (ill most likely use this one) to allow the head to tilt a little . I'll have to experiment with that or a static bearing. Main thing is that you will be able to turn your head. I will also 3 print some pads to spread the load and get around the headphones on the DAS.

    Here's the general layout but it will have a setup for moving back and forth and from side to side. Most likely using springs for extra dampening and some safety between the motors and the frame itself. It will also have physical stops. Since i dont have actuators i need to figure out the best way for it to move on a plane without tipping up or down. Ill have to experiment with this. Another thing i'd like to add is a flip up system with a quick slide lock for getting in and out without much hassle.

    Here's the general idea

    helmet.png
    Last edited: Apr 7, 2020
  2. Trigen

    Trigen Active Member

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    Current design. Getting parts next week so ill design some brackets for the motors and everything else for 3d print. Motors may be changed at a later date

    Here's a sketch of the preliminary design. I decided to go with a thread and spring based design for the sides as its easier to do in relation to Surge. I may 3d print a U joint, grease it up and cover it with a Ninjaflex flexible filament cover while i wait for a metal one



    Current design.png
    Last edited: Apr 8, 2020
  3. EduardoMoreira

    EduardoMoreira Member

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    I am curious about this project. Keep updating..
  4. dedraro

    dedraro Active Member

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    Nice concept, maybe you can find inspiration from the ADAS simulator, which has something very similar, I leave you a video and follow the topic

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  5. Trigen

    Trigen Active Member

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    Thanks! i've seen it before and was really wondering where the heck it was! I really wonder what motors they are using since he can move his head freely when its not on. I asked about it in a new post too. I've gotta try and figure it out. Really liking the setup, ive done the same on a joystick with dampers. Should not be so hard to do for a sidemounted system on the head either but ill have to see what angles works the best since they are a bit apart
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    Last edited: Apr 10, 2020
  6. Trigen

    Trigen Active Member

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    I'd definitively going with that design. I may actually add a couple of dampers for pocket bikes with compression spring on them given that wiper motors can be a bit harsh. Mine does 60 rpm so that's more than fine.
  7. BlazinH

    BlazinH Well-Known Member

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    How good does the loading feel on the helmet and your head when using such a high center of gravity? I'm using a head strap system instead that keeps the cog in the middle of your head except for acceleration surge due to the fact that there's a seat back there. The problem I had with its high loading was it pulling the head strap right off my head during acceleration. The solution was to add a chin strap to stabilize it but you still can't apply nearly as much force to it as you can in all other directions. Luckily for acceleration you don't need as much as the others to be effective.
    Last edited: Apr 15, 2020
  8. Trigen

    Trigen Active Member

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    I'll most likely be doing springs on my levers or in some other way for the same reason.
  9. Trigen

    Trigen Active Member

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    Any suggestions for spring strength?

    (see below post)
    Last edited: Apr 15, 2020
  10. Trigen

    Trigen Active Member

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    if split the rod in the middle inside the housing and have some preload on each of the springs. I probably need 4 to make this work or 3 with one in the middle. And using a weaker spring ( the outer ones) inside for acceleration. Conical springs is also an option for a compact solution

    4 spring.png

    triple spring.png
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    Last edited: Apr 15, 2020
  11. BlazinH

    BlazinH Well-Known Member

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    How do your springs limit torque or do they provide the torque?

    I use springs also but it appears for a different reason. I use torque only motor drivers therefore when a force ceases there is not a return to what would be considered neutral position because positional feedback is not present. In real life your head naturally snaps back to a position that feels natural and that's how my system works too. However there is some inherent resistance to movement in my actuators drivetrains so I use springs to provide just enough counterforce so your head doesn't feel a resistance when righting itself.
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  12. Trigen

    Trigen Active Member

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    Id really like to know the specifics of those torque only drivers but i can understand from a commercial perspective if you dont wish to share it. Feel free to PM me if you dont mind doing it privately though and no worries if you dont.
  13. BlazinH

    BlazinH Well-Known Member

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    A torque driver is a pretty simple thing. It works by outputting voltage that's proportional to input. So when an input is present a continuous and proportional voltage will be output. When an input is neutral then and only then output becomes zero volts.
  14. Trigen

    Trigen Active Member

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    Thanks but what I'm trying to figure out is if this is a hardware motor driver. While dosent seem to be i may need one with current sensing output or solely done by software? If the latter would I be close by saying I'd need to program a dynamic PID ( like kp in smc3) that takes the serial data and turns that into current? Would it be possible to modify the smc3 sabertooth sketches or get the jist of it from there? It's all done from the potentiometer position and at a set speed and current now right?

    I highly doubt my wiper motors are suitable for it and my spring system would be better (but it kind of forces your head back to neutral) but I'd really like to have a crack on it for for later and perhaps even combine the two. Then using a spring on the levers to help push them back to neutral. That's if it won't be to strong for the motor to push against
    Last edited: Apr 17, 2020
  15. Trigen

    Trigen Active Member

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    @SeatTime Do you happen to know what spring strength you have on yours?
  16. BlazinH

    BlazinH Well-Known Member

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    My normal thinking is a motor controller outputs a varying voltage so that's what I stated but maybe I should have said outputs variable current instead since it takes both to make power. Speed isn't involved since a torque driver outputs torque. In fact motors operate in a continuous stalled state for the most part. Because of this wiper motors are usually not suitable IMO. SMC3 may work as a torque driver by attaching pots to the arduino but not the motors. Set them at 2.5v or in the center of the graph in utilities. Use kp only. Might also need a little deadband added if pots aren't perfectly centered..
    Last edited: Apr 17, 2020
  17. dedraro

    dedraro Active Member

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  18. Trigen

    Trigen Active Member

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  19. BlazinH

    BlazinH Well-Known Member

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    While the positioning method works to an extent its quite unsophisticated. If you don't keep your head perfectly static and centered at all times the force response unrealistically diminishes (or increases) when it should stay constant regardless of your heads position . Torque drivers don't suffer this ailment and is why I use them instead :).
  20. Trigen

    Trigen Active Member

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    Feel free to give a link to your hardware or something similar then?...