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Found this photo of a 6DOF and it might have advantages?

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Zed, Jun 2, 2019.

  1. Zed

    Zed VR Simming w/Vive

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    I was looking at various designs for a compact 6 and came across this photo as part of a google search. Instead of putting all the motors on the base, there are two levels. The obvious disadvantage is height but it’s just the height of the motors/gearboxes.

    You guys would know - any disadvantages to this arrangement? The output arms all look the same length but the geometry is obviously asymmetric. Would it make a difference?

    The search link was for http://servosandsimulation.com/products/six-axis-6dof-motion-base-platform-systems/ They have some interesting articles but don’t care much for homebrew/hobbyist systems: http://servosandsimulation.com/2018/08/10/should-a-motion-platform-cost-5k/

    This one looks like a bulldog, though, and this arrangement would let you use bigger motors/gearboxes than would otherwise fit a desired footprint.

    61C77AE3-8B26-46DC-A3AA-9D431C27F58F.jpeg
    Last edited: Jun 2, 2019
  2. BM114

    BM114 New Member

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    Speaking for the motors and gearboxes: so long as they have the required power capability I wouldn't see a problem with it as long as you can individually tune each actuator profile.
    Software wise it looks like it might be a little difficult to tune though I'm not familiar with simtools and its capabilities yet.
    I would be concerned with the size of the base looking at it, as while it would have a dense center of gravity I would wanna test it out in simulation for tipover hazard with your intended load.
    In conclusion, since the price of the 6dof platforms like that are primarily in the actuators (especially in the one I hope to build) it seems like you could waste a lot of range for the price you pay. (If range is what you are after)
  3. Zed

    Zed VR Simming w/Vive

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    Since I run in VR I’m not so interested in range - just getting all the various motions and having sufficient range to feel it. Not looking for really extreme movement at least until the motion cancelling gets more sorted. I think the short link rods might limit the range of motion and that’s OK. I just don’t want weirdness but I think as long as movement is never extreme for the short link rods, the geometry would be essentially as if all link rods were the same length. Differences would maybe only show up at extreme motion. This geometry is a bit hard to wrap my head around but it might just work and let me use bigger/cheaper motor/gearboxes but keep it all in the frame size I can do for my space. I guess I need to break down and learn how to model this kind of thing to see it in virtual action.

    That’s not my rig in that photo, looks like a lot of muscle there, and is just an example of the stacked actuator layout I’ve been considering. I’m trying to get a small footprint when not in use, but swing-out outriggers/feet to get additional stability when in use are certainly in the mix. My rig is 2' x 4' right now and I’m hoping to stay in that footprint.

    Cheers!
  4. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

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    Might be worth modelling first to work out the geometry, as it is a bit of an unusual design.
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  5. pmvcda

    pmvcda aka FlyPT

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