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Trip's G-seat project (primarily for flight)

Discussion in 'DIY Motion Simulator Projects' started by Trip Rodriguez, Nov 19, 2019.

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  1. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    @MarkusB I had time just now to sit and check out your thread on the G-vest. Using a medieval plate armor was epic! I got quite a bit of useful information from your thread, thank you.

    Here's my plan for the vest at this point after reading your thread:

    The sway and heave action of the vest is going to mostly just help my body move with the sway and heave action of the backrest. I think that to some extent it will be kinda attached to the backrest in fact. This way instead of only the back rest friction against your back pulling you over, the force is against your back and also the rest of your torso.

    My concept is that the vest will be attached to the backrest and when you sit down you will pull it around you just like the harness and attach it at the front.

    I'm planning to try to use something that is stiff, but not completely rigid to distribute the pressure over as much surface area as possible.

    My #1 main goal with the vest is to crack my ribs if I pull too many G's in the F-14, F-16, and F-18. =D Seriously though, I want to have enough pressure applied that when G-lock starts coming on I ease up on the turn because it's legitimately unpleasant.

    I should be able to play around with having the vest sway and heave exactly 1:1 with the back cushion, and also having it move more and move less via a simple mechanical way to change the ratio. I'll see what works best for me. If I really just don't like it I can disable everthing except positive surge.

    I never had any plans to have the vest pull me forward for braking etc. I'm going to rely on the G-seat to move me. At least, that's the plan.

    All of this really is such a tricky balancing act!

    The one thing I think would be really beneficial that I don't have in my design is to actually pitch the entire G-seat forward for negative surge accelerations. I find that the feeling of "falling out" (forward) of the seat is very powerful. To best achieve this I feel like I'd have to lower the front edge of the seat a bit. I will instead only be able to raise the rear edge and tilt the back forward.

    Damn, now I'm going to be thinking about how I can achieve a little of this with my existing system! Off the top of my head I kinda think there might not be anything preventing me from replacing the front "legs" of my seat (pictured above) with moving parts and attaching that to the surge actuator. I'm not talking about a huge dramatic movement, just lowering the front edge maybe an inch or so under max negative surge.
    Last edited: Feb 14, 2020
  2. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    Ok, already got it figured out. =)

    Instead of the four legs under the bottom cushion part there will be a "see-saw" with two arms coming down to push and pull (forward and back) on.

    Even if this isn't useful for cues it will simply give me a better way than originally planned to adjust the angle of the bottom cushion which I had planned to be able to do anyway.

    Edit: I don't think I'm going to play with actuating this unless I decide I need something more for sustained surge after using the seat. I do think I'm going to plan on having the seat bottom angle adjusted to a little less angle than I had planned initially which will make the heave tilt of the bottom cushion have better effect in this regard.
    Last edited: Feb 18, 2020
  3. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    Wow, I haven't posted here in longer than I thought!

    My brain has still be going crazy with various different ideas I've had for possible G-seat innovations. I've got something I'm going to be experimenting with. =) So the G-seat design is still up in the air after all.

    In the meantime, construction of the elevator is underway!

    I decided that it was just a bad idea to try to operate the elevator with only two actuators in an effort to free up one additional actuator for the G-seat. I'm going back to the original plan of using three ballscrews for the heave motion. If I feel I need more independent axes for the G-seat after some testing I can deal with it then.

    Since I'm going back to three actuators I decided I could really clean up the looks of the elevator. I'll attach a drawing, though it's incomplete and I broke part of it. =P

    Design Progress:

    I've got the design and dimensions for the elevator finalized. (image attached)

    Today I took several hours of time working everything out to tackle the motor mount problem, and found that there was no problem! It was such a simple design it makes me nervous that I missed something! A couple pieces of angle, and a laser cut 1/4" acrylic motor mount that bolts to the angles. (image attached)

    Physical Build Progress:

    The moving platform frame is cut and some of the holes are drilled for the SBR12 bearings. I'm holding off welding it until I can use the finished front actuator to make absolutely sure that I'm making the holes for the linear guide blocks the correct distance apart.

    Yesterday I pilot drilled and final drilled the 120(!) mounting holes in the towers for the SBR12 guide rails. They are all done.

    Next comes welding the tower halves together. I probably won't get to work on that until Wednesday but things should progress quickly from there. Once they are welded I can drill the mount holes for the ballscrews and then use the finished unit to check drilling dimensions on the lift platform frame. Drill those holes, weld the frame, and then set everything up and finalize dimensions for the lift tower support frame (now made of angle on the floor) Finally weld the lift towers to their frame and then it's time for finish work and paint.

    elevator.png motor mount.png
  4. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    Well, once again I think I'm basically done designing. =P

    I don't have all the dimensions and framework figured out for the latest G-seat design but I believe all the juicy bits are there.

    I'm much more satisfied now, as the design contains some significantly different ideas from what everyone else has done. I'm actually not sure I'm going to want to reveal all the details in case there's a chance I can turn this into a source of income, but I probably will give up that idea and tell all in the end.

    The basic gist is that my experiments made me feel like the positive G cues not applying pressure to the tailbone and Ischium was unsatisfactory. As a result my final (yeah yeah, I know!) v.1 design is working somewhat opposite SeatTime's and similar.

    For positive heave instead of dropping the center down and raising up the edges, I'm dropping down everything except the part under those bones (and also the very edges of the seat which will squeeze up and in a bit on the thighs). This way I still am being lowered down, but when I do so, there is increased pressure where I think I feel it most. The panel for the tailbone and Ischium bones is stationary, though I might find that I need to make it move somewhat after testing.

    There's another trick up my sleeve as well, but for now that remains top secret. =)
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  5. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    Alright, so this is hopefully the final design (for v.1 anyway) for the G-seat. Dimensions are not yet final and there are bits missing. Not set up for animation, just a still shot.

    The yellow frame moves in the roll axis. The red frame is stationary. This frame is what I'll mount adjustable side bolsters (a la SeatTime) onto and also supports the upper seat back which doesn't move to hopefully provide friction on my upper back to make the lateral G cues more convincing. If that doesn't really work out I can just extend the moving part of the seat back all the way up. I'll make that frame bolt on, so it can easily be removed.

    I'm not sure yet how I want to mount adjustable/removable side bolsters for the seat bottom. I also might just make those wings on the bottom get pushed all the way vertical when the seat rolls, but that still requires adding a non-moving frame extension of some sort. No big deal, but I'd like it to look decent.

    The fancy paint job is just to make it easier to see the various components.

    March_2nd_G-seat_render.png
  6. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    Not very impressive I know, but I've finally got a photo of a little bit of real progress.

    Tonight I washed the oil off the parts and welded up my actuator towers for the heave elevator.

    I did make the kind of mistake typical for me, but it's not the end of the world. I decided when preparing to drill the holes for the linear guides that it would be a good idea to offset them slightly to the bottom end, just in case space wound up tight at the top mounting the motors. Well that's all well and good, except I failed to realize that angle iron is asymmetrical, and half of them were rights and half lefts so I needed to offset three to one end, and three to the other. The only real consequence is the hardware on the outside of the towers will be visibly a little bit off, which will probably drive me insane cosmetically on the front tower where they are side by side. I'll probably add some kind of trim to cover it up when I'm doing the finishing work. LOL, Oh well, I've done much worse! You can see it in this image, the drilled holes in the center tower.

    Next I'll be drilling/test-mounting the 1500mm ballscrews to these and checking alignment Progress at last.jpg . After that I can verify the dimensions to make the bottom frame that will hold all these in place, weld it together and paint everything, and the elevator will be well on it's way to completion.
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  7. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    A quick update for my friends here since I've long been silent. My Dad's health took a serious turn for the worse in March so all of my free time was dedicated to him after that. He passed away a couple weeks ago and I'm left extremely busy with being his executor and preparing his house (which needs quite a few major repairs) for sale so we can pay off the mortgage etc. At present I'm buried in paperwork, cleaning everything out of the house and property, disposing of what we aren't keeping, and moving all the rest to my own home and/or my brother's home which is five hours drive away. Once that is all done I will still be busy with lots of repairs and some renovations so we can try to sell the house for a bit more than is owed to boost our finances a bit.

    As soon as all of that is done and things settle down I'll be back to working on my projects, though renovating my own home will once again likely become my top priority. That project got put on hold a couple years ago when I made the decision to move back in to Dad's place to care for him, so the inside of my home is still all torn out.

    But have no fear (or maybe for some of you, it would be hope!) that I'm gone! You'll be hearing from me again plenty, starting probably in the fall or winter. For one small silver lining, this means from here on out I'll be building the sim in what is likely to be it's permanent location rather than initially having it at Dad's and then having to move it which was the plan previously.

    Trip
  8. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My condolences for your loss, take care and I look forward to the resumption of your project when you get through the plethora of other pressing commitments.
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  9. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    Thank you Noorbeast.
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  10. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    Sorry for your loss. I hope the succession is not to much of a burden after that. Take care and see you soon.
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  11. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    Thank you Pierre
  12. SeatTime

    SeatTime Well-Known Member

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    Very sorry for your loss, also lost my Father to Cancer a few years ago - never a easy time.
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  13. SeatTime

    SeatTime Well-Known Member

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    Just a question on your new rig when you have the time - for your three heave motors - what happens if one, or two motors don't drive for any reason, as it looks like the failed/disabled motor will stop the others from moving.
  14. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    @SeatTime Thank you, and sorry to hear about your father as well.

    I had the same thought and question and discussed it in Thanos's Discord a while back. The reaction I got was "they won't fail!" based on the fact that they are proper servos with proper drives and not home made.

    I'm certainly not willing to bet real consequences on that, so I do feel like I need to do something to protect the machine and user if/when that should happen.

    I've had a couple of ideas but haven't actually chased this down yet. The two ideas I came up with are an emergency stop "mercury" switch setup that triggers as soon as the sim goes much off level as a result of one of the motors not doing what it is supposed to, and perhaps having all three actuators attached to the platform with "shear pins" so that severe damage is unlikely to occur while the sim malfunctions and tilts enough to trigger a sensor. There would be a hard stop above each actuator shear pin attachment point, so the sim could never fall from the shear pins breaking. I figure that when one actuator shears the pin and becomes unsupported one one or two sides the sim will quickly tilt enough to trigger a tilt switch and activate a complete emergency stop. I'd need adjustable tilt switches, and I'd tune them so that they have only a little bit more dead zone than is needed to prevent them from triggering during normal operation.

    If you have any better ideas let me know! I'm fairly concerned about this particular issue.
  15. SeatTime

    SeatTime Well-Known Member

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    "they won't fail!" Maybe he would not be so confident, if he was standing next to me a few years ago when a multi-million dollar radar we were commissioning had a -servo drive failure of a similar type and proceeded to rip itself apart :eek:. Solution? - working through this as we speak for my own new rig.
  16. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    LOL yeesh, that doesn't sound like fun. Let me know what your solution is.

    What do you think of the tilt/mercury switch idea? The only problem I see is being able to have it sensitive enough to stop the machine before damage occurs, while also having it not so sensitive that it triggers during rough normal operation.

    Wait a sec, your new rig? Did you decide to add motion back to the sim? I'll have to take a look at your thread. The way I see it the ideal setup is a G-seat setup like yours, plus 6DOF but not using pitch or roll to simulate accelerations.

    I have another very unique top secret design I want to try too, but it will take up a lot of space and figuring out how to drive it may be an issue. Not sure if I'll be able to try it or not but I'm thinking about it. ;) I'll revolutionize the industry! =P
  17. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
    DC motor, AC motor, Arduino, Motion platform, 6DOF
    Current sim is working well, so really in no rush. I really love the easy access of the 'seat only' design (see latest posts in my build thread)as allot of my older friends struggle to get into even my current sim (the 6DOF was impossible), but there are issues in hanging a heavy DD wheel off it for cars.

    As for ideas - I have always wanted to build a 'Arm type' centrifugal capable sim, but don't have the space or spare cash.
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  18. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
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    Maybe a misconception about my current sim... it is not just a pressure base sim, but does move in all DOFs like my old Stewart Platform - but different. Just checked: Yep all there: surge, sway, heave, pitch, roll :). It's just that my current heave moves the body down to replicate being pushed down into your seat. I would just like to have back also the heave lift to close it all out - note that my seat does heave slightly via the seat base paddles heave, but that is meant to be more of a pressure based effect.
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  19. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    I've never seen an arm type motion sim that had all the requisite features IMO, but it would be really fun and cool to design one! Ah, the things people like us would do if we had ridiculous amounts of money.

    I don't play the lottery, but if I won it the main thing I'd be spending money on is this hobby. With an eye toward commercializing the resultant design too, if I end up with something good enough. Thinking of the way most lottery winners waste their winnings ruining their lives kills me. D;
  20. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
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    I only build DIY for pleasure and cost effectiveness as I think there are more then enough players in the commercial sim market as it is. If you have something special, it will just be copied as soon as it is released.
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