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Question Carbon Frame 6DoF questions.

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Psionic001, May 24, 2018.

  1. Psionic001

    Psionic001 Active Member Gold Contributor

    Joined:
    Mar 5, 2017
    Messages:
    138
    Location:
    Sydney
    Balance:
    1,002Coins
    Ratings:
    +59 / 1 / -0
    My Motion Simulator:
    Motion platform, 6DOF
    Hi all.

    I’m building a 6DoF linear actuator rig and hope to share it here once construction has started, but I had some lingering questions to start and hope I can get some feedback from you guys.


    Frame
    Has anyone built a great light weight Carbon Fibre rig for lower inertia and better fidelity? (I have some good experience with composites so I’m not afraid of the frame build. ) I imagined there would have been some builds here but I couldn’t find any.


    Is a sunken frame really worth the planned effort Vs a simple seat on top platform? I’m hoping to sink the seat in the frame to lower the CG and keep the frame size smaller but it is a significant extra effort in design time and construction (moulding)


    U-Joints
    Does anyone use 4 bolt flange bearings as a base for their actuators to provide the rotation component of the actuator movement? I’m thinking they would serve as a good base, and have a vertical shaft with cross bolt hole in it to connect to actuator end forks if that makes sense.


    Actuators
    Currently my actuator travel is 400mm at 500mm/s and can push 100kg each. Collapsed actuator is 78cm long. Is that enough speed? I’m kind of locked in, but could always get bigger motors. Stroke length of 400 I imagine is enough.


    Seating
    For seats I like the idea of a tilt adjust seat (for flight sim comfort and driving), but a one piece seat (race car style) is much much lighter. Any opinions or recommendations here? Currently looking at a Sparco R333 seat but I’ll be sacrificing fidelity with every kilo I add.


    VR sickness
    Does it generally diminish when a motion rig/platform is introduced, Vs no rig at all?


    Rig Size
    Which brings me to my big question.
    Any tips to keeping my platform as small and compact as possible, yet allow the full travel and movement expected from my large actuators? This is a home office rig, so the smaller the better physical size combined with the largest delta movement is the aim. But my gut feel is that they are mutually exclusive.


    Hope these weren’t stupid questions, they seem fundamental to nail down before I get stuck into this build.


    And I welcome any other input as I’m really unsure if there’s anything significant I’m missing.


    Thank you.
    Last edited: May 24, 2018
  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Joined:
    Jul 13, 2014
    Messages:
    20,463
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    144,614Coins
    Ratings:
    +10,741 / 52 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    • Agree Agree x 1
  3. SeatTime

    SeatTime Well-Known Member

    Joined:
    Dec 27, 2013
    Messages:
    2,574
    Occupation:
    Retired
    Location:
    Brisbane Australia
    Balance:
    28,370Coins
    Ratings:
    +2,844 / 38 / -0
    My Motion Simulator:
    AC motor, Motion platform
    Frame
    Has anyone built a great light weight Carbon Fibre rig for lower inertia and better fidelity? (I have some good experience with composites so I’m not afraid of the frame build. ) I imagined there would have been some builds here but I couldn’t find any. Yes, see my build thread, although it's just one picture now. The frame weighed less than 2kg. Have gone in a different direction now. Once you add a heavy DD wheel, it becomes a bit irrelevant, so I needed to find other solutions to that problem. .


    Is a sunken frame really worth the planned effort Vs a simple seat on top platform? I’m hoping to sink the seat in the frame to lower the CG and keep the frame size smaller but it is a significant extra effort in design time and construction (moulding). Depends, as Simtools does not currently use 6DOF math with an adjustment for were the roll center is, it is almost mandatory. As without this, it would be like driving your car from near the roof. Of course, this will effect how much your rig can move.


    U-Joints
    Does anyone use 4 bolt flange bearings as a base for their actuators to provide the rotation component of the actuator movement? I’m thinking they would serve as a good base, and have a vertical shaft with cross bolt hole in it to connect to actuator end forks if that makes sense. I and many others used a uni-joint.


    Actuators
    Currently my actuator travel is 400mm at 500mm/s and can push 100kg each. Collapsed actuator is 78cm long. Is that enough speed? I’m kind of locked in, but could always get bigger motors. Stroke length of 400 I imagine is enough. Depends on the design of your rig and how heavy your rig will be. But your specs look fine for most current designs.


    Seating
    For seats I like the idea of a tilt adjust seat (for flight sim comfort and driving), but a one piece seat (race car style) is much much lighter. Any opinions or recommendations here? Currently looking at a Sparco R333 seat but I’ll be sacrificing fidelity with every kilo I add. Depends on your budget. Buy the best/lightest you can afford - your going to be spending some time in it .


    VR sickness
    Does it generally diminish when a motion rig/platform is introduced, Vs no rig at all? From my and others experience , Yes.


    Rig Size
    Which brings me to my big question.
    Any tips to keeping my platform as small and compact as possible, yet allow the full travel and movement expected from my large actuators? This is a home office rig, so the smaller the better physical size combined with the largest delta movement is the aim. But my gut feel is that they are mutually exclusive. Agree, but FI, when I added G-systems to my rig - long surge and sway movements are now not so necessary.
    Last edited: May 25, 2018