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Seattime's Sims

Discussion in 'DIY Motion Simulator Projects' started by SeatTime, Mar 8, 2018.

  1. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
    DC motor, Motion platform, 6DOF
    I agree that heave, or Positive/Negative Gs in a Aircraft is the most predominate force that you mainly feel. I am expecting to fill most of these large forces with a combination of paddles, harness belts and a variation on my old vest system for my torso and thighs, maybe even a add-on for my head system, which as most people know is a very sensitive part of the body to these types of forces. Deceive the head and often the rest of the body will follow ;).
    Last edited: Nov 4, 2019
  2. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
    DC motor, Motion platform, 6DOF
    FI, the heave system uses two 'Second Class' levers to increase the effort of the motor 2.6 times. Obviously you will lose some travel to gain the extra effort, but I don't require allot anyway.
  3. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    My Motion Simulator:
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    For years I've had an image stuck in my head from something I saw at a theme park. After the passengers were seated the whole floor (probably 30 feet square) dropped down on ballscrews. I'm considering that approach for heave. The base upon which everything is built will be an aluminum frame that rides up and down on guide rails. This frame will need to be the length and width of the cockpit and no more. With that design I should also be able to minimize the weight of the cockpit, but until I have an idea of what the whole rig will weigh there's no way for me to know how much power I'll need to move the sim up and down fast enough to be effective.

    @SeatTime I'm a bit obsessed with your vest concept and for my G-seat I've been thinking in terms of taking that type of system as far as I possibly can. I've got some pretty cool ideas I think might work. Any comments based on your experience are welcome.

    Another amusing note @SeatTime a little while back when I was considering eliminating the 6DOF (and even made a post here about it) one of the key data points I used that lead me to stick with the 6DOF base was thinking "well, if the 6DOF wasn't really worthwhile I'm sure SeatTime wouldn't still be using it". LOL
  4. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
    DC motor, Motion platform, 6DOF
    The heave in my new setup is not meant to move allot and it will only be the base of the seat, harnesses and vests were required. In the seat base, on top the heave layer will be surge and then a sway layer with the same parasitic setup which I have used in the seat back (current seat base will be removed). I have purposely decided to drive both the bottom and back of the seat independently for good reason. As a example, a rundown on what would happen for the main forces is below:

    Note: The amount of force/movement being applied to either the seat base, or back can be adjusted independently as required.

    Heave : Aircraft is climbing - seat base will go down, parasitic paddles will be forced up on both sides, gripping your bottom to simulate being pushed down into the seat by positive gravity. You will also feel a differential with the stationary seat back just like you would in real life and any hand or feet controls. There will also be pressure applied to the top of the thighs, head and possibly chest.

    Heave: Aircraft is diving - seat base will go up, parasitic paddles will be forced down, releasing any grip on your bottom to simulate being lifted away from your seat by negative gravity. You will also again feel a differential with the stationary seat back and hand/feet controls as before, but this time in the opposite direction, just as you would in real life. Top and bottom harness will tighten, as they would in real life.

    Surge: Aircraft accelerates: Seat back will tilt back, parasitic paddles will be forced up on both sides, gripping your back, the seat base will also move back also pushing you into the seat back, like it would in real life. Depending on the acceleration the top vest may also pull you into the seat back.

    Surge: Aircraft decelerates: Seat back will tilt forwards, parasitic paddles will be forces back, releasing any grip on your back, the seat base will also move slightly forward moving your body away from the seat back like it would in real life. Depending on the deceleration the top and bottom harnesses will also tighten.

    Sway: Aircraft has a sway event, either left or right: Both seat back and base will move left or right as required, as this force increases the parasitic paddles will raise on the required side and push on that side of the body as would be the case in real life. Head system will also apply sway force were required.

    Hope that explains what I am expecting to achieve.
    • Informative Informative x 1
  5. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    Thank you for that SeatTime, it explains a few details I was confused about and inspires me further.

    I had typed up a nice description of what I'm thinking hoping for some comments, but I got distracted and never hit the post button and it disappeared. :/

    The short version is I've been thinking about expanding the vest concept to be full 6DOF and help lift me out of the seat a bit and push me down into it. Still a lot to figure out on that, like how to do negative surge. I'll still use harness tighteners and have heave in the bottom cushion to help with the lifting. The idea is to have this thing have stiffeners like a corset, and attached to the seat. When you sit down you just pull it around you and put the front together with velcro.

    I'll definitely leave some openings for friction against the seat as I move, that's a great detail.

    For the motion sim I'm thinking I might need to have the seat and probably the pedals and hands on controls be able to pitch and roll a bit mostly for Euler angles in helicopter pick-up, hovering, and touching down. Also useful for changes in angular velocity and Euler angles in cars on hills. I'll probably want to have a traction loss axis as well and then the whole thing will be on a ballscrew powered "elevator" for the heave axis.

    If I build the G-seat first and test it I can scratch any parts of the motion sim that I don't feel are needed, and I can also still add things I don't think I'll need like a surge and sway table. Sway is super important for helicopter simulation according to an old NASA/DARPA study I read. Yaw not needed at all.

    @SeatTime I'm going to need a bunch of Bowden's for this, any suggestions for buying them? I'd also like to know the wire size on yours so I can be somewhat confident the ones I order will work.
    Last edited: Nov 5, 2019
  6. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    My Motion Simulator:
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    Ok so I had to get back out of bed to say I've decided I was being an idiot, and I'll most likely stick with a standard Stewart rig under my G-seat. Why? Well the fact that I think I need a big heave axis negates most of the benefit of eliminating the 6DOF!

    It makes more sense to just build the 6DOF and use it for the heave and small cues on other DOF's, and then if I decide that I need more or stronger cues it's just a matter of software settings.

    The G-seat plan above remains the same.
  7. BlazinH

    BlazinH Well-Known Member

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    I hope I don't offend you by agreeing :). But mostly because you already have actuators coming. Bottom line though is there is just no way to replace the feeling of displacement from prolonged heaving imo.

    I'm still really liking my 2dof w/TL for racing with VR however. You say within the car and every thing is as it should be. I get great road surface awareness but do miss out on the feeling you get from elevation changes other than abrupt ones like curbs, etc.

    But when I was using 15 inches of heave I really loved how Super trucks felt for example when I would hit a jump, go up, and then hope I could control the landing. It felt almost feel to the best of my knowledge.

    However g-seat heave as SeatTime will implement is great to have with VR not only for haptics but for visual feedback too. In this case motion cancellation is opposite of what you want.
  8. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    How dare you agree! ;) I shall riposte by agreeing with you!

    As I've said before I'm an idiot. I have a high IQ, but I'm an idiot nonetheless!

    I bought the servos and the AMC to run them, but they could be used for anything since I haven't ordered the rest of the parts yet.

    I agree 101% though about heave. It's not even just that it's the thing you feel most in flight, for me it's also the feeling that brings my mind into an almost euphoric state for being in the air. I also think it's the most "fun" axis in racing even if it doesn't contribute much in terms of information.

    There was no way I was going to build without a heave axis. I've got 15" (381mm) now and its' pretty great. My new rig will have over 20" (508mm) and I'm hoping quite a bit more. =D
  9. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
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    Guys, like I said further back, not expecting anyone to go my route, just documenting some of what I am doing :). I am although confident of fooling my body with the setup that I am building. Big movements look cool and can feel great, but certainly come with their cons as I know from my own experiences. @Trip Rodriguez ,Look forward to seeing your big heave beast :thumbs. FI, I am not using a Bowden system for the main heave - nor would I recommend it. Bowden systems can have some flex when moving allot of weight and I like to feel the road texture through my heave. On that note, as part of my new heave system is the adding of a 'shock' adjustment system. Which enables me to easily change out 'inserts' which can physically change the suspension characteristics of the system for different cars or even aircraft. I think this will give a better and more realistic suspension feel then any software algorithm ever could. One of my 'shock' inserts is shown below: They will still feel reasonably hard, but not like you are riding on block wood suspension as it sometimes can feel with our systems.

    Heave shock-system.jpg

    Heave shock-system2.jpg
    • Creative Creative x 1
    Last edited: Nov 6, 2019
  10. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    Oh I was definitely not thinking of trying to actually lift my weight with bowden wires! I just meant to have the vest pull up along with the bottom cushion, which would be on a linear actuator or lever system,to perhaps distribute the pressure more evenly.

    Now I'm thinking of more heavily using moving seat panels. I love the idea of the parasitic wings.
  11. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    @SeatTime I'm in the process of deciding how to build my top frame for the new linear 6DOF. To build it in aluminum instead of steel I have to buy a welder for ~$500USD, get a bottle of Argon, get aluminum filler wire, and about $100 for the square tubing. Should I consider building it out of carbon fiber? I expect it to be too expensive for me but I'd like to have an idea of the cost before I rule it out. Not sure what material to use so I can't really price it out.

    I've worked a little bit (badly) with fiberglass, but I'd actually make an effort to learn the correct way via youtube tutorials before starting to lay anything up for this.
    Last edited: Nov 6, 2019
  12. adgun

    adgun Active Member

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    Aluminium welding isnt easy bether to let it do
  13. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    I've got some gas, MIG, and flux welding experience so I'll manage with the aluminum. I'm going to MIG it not TIG it so it's not that hard. A lot harder than steel yes, but I should be able to manage with a little practice on scrap first.

    Big advantage to doing it that way is I'll now own a spool gun MIG for future aluminum jobs so I'll probably go that route but I wanted to ask about the carbon fiber just to check it out.
  14. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
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    If your upgrading to high power AC servos, then just make it out of box steel, really not that heavy.
  15. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    My Motion Simulator:
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    My frame is larger than most (58" on the long sides between joints at the top frame) to allow for cockpit panels. Also it's going to have an upper structure for supporting overhead helicopter panels. I estimate the whole frame in aluminum around 30 pounds and steel around 115 pounds.

    I can always make a replacement frame out of aluminum later. If you think it's worth giving it a try I'll go for it. Your builds more than any other are what have made me conscientious of my heavy steel frame.

    I am going to have 6KW (8HP) of motors pushing the heave load up together so probably not a huge deal.

    Also I could likely reduce the weight and cost by going to smaller steel tube, but I have no idea what size it really needs to be to take the punishment. My main frame is 2"x 2"x .187" square steel. Probably pretty serious overkill.
    Last edited: Nov 6, 2019
  16. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
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    I had always gone as light as I can due to using 12VDC motors. I have seen those high power AC servos motors easily carry two people. I would just use your current rig, with maybe just the upper structure for the control panels made out of something light.
  17. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    I'll go with steel then, that saves me a lot of money so thanks! I have to make a new frame regardless, the new dimensions are radically different since I'm going from rotary actuators to linear. Also with the old rig the upper actuator joints were below the (cockpit) floor, this time they will be up nearer where the CoR should be. They will still be a little below proper CoR because of clearance concerns, but around 15" or so higher than the old sim.
    Last edited: Nov 7, 2019
  18. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    SeatTime, have you made much progress on the seat bottom mechanism? I'm starting to figure out my rig and hoping for a new inspirational photo. =)
  19. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
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    Been busy with Tensioners and my other hobbies, but have nearly finished the heave actuator and its attachment frame. Still waiting on parts to upgrade the seat bottom G system.

    Heave Actuator.jpg
    • Like Like x 3
  20. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
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    Have been testing out my new seat base heave setup (still waiting on parts for the surge/sway parts) The whole bottom seat raises up and down with the paddles parasitic in operation (they move up when the sea base goes down and move down with the whole seat base moves up, similar to how the back seat setup works. Really impressed with it, as because it is using a 2nd class lever to increase torque, it also increases operational smoothness and fine detail, even with 10 bit data and a standard DC motor and analog 5 turn pot. Edit - seat base sway/surge parts just turned up, so out it all comes again for modifications :).

    New Rig Heave system.jpg


    Heave Actuator setup.jpg
    • Like Like x 3
    Last edited: Nov 15, 2019 at 13:00