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G-SEAT

Discussion in 'DIY Motion Simulator Projects' started by gforce, Jul 26, 2020.

  1. gforce

    gforce New Member

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    Hi guys. Inspired by years of studying others building parts for sim rigs I am going to attempt to stand on the shoulders of giants and push the envelope a bit with my g seat build. Giants the likes of Michal Burisin, @RowanH , @Thanos , @SeatTime , @yobuddy , @pmvcda aka FLYPT, @HoiHman , saxxon66, and many more who I've learned from and drawn inspiration from. Thank you guys!

    I have been dreaming of doing this for some time and only now due to the passion and faith of a new friend can I see this project come to reality. I will be building one for him, then one for me.


    Only after building a dbox/sfx style rig did I realize just how important a g seat and g helmet are to the experience. One of my goals for this project is to confirm my suspicion that the chassis motion should come only as the “dessert” of a motion sim while the gseat/helmet are the “meat and potatoes”.


    I hope that my build log here will educate and inspire the way so many before me have done for me.


    My current idea is to combine a seat mover and a gseat for both the torso and the seat pan separably. I am also thinking the seat pan should be on sliders for surge. I will be using industrial servo motors from china.


    I have been playing with a cad model of this but its so rudimentary that I will save it for when it’s a bit more mature.
    Last edited: Sep 7, 2020
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  3. gforce

    gforce New Member

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    The current task on the list is to do a hinge study. I have always wondered where the best location for the hinge in a paddle style gseat should go.



    So I played around with some wood trying to get a good shape to the paddles.
    I am trying to use flat panels because down the road I will incorporate exciters and vibration isolation them. This will allow maximum energy transfer to the driver rather than the chassis.
    20200725_170139.jpg
    20200725_170136.jpg
  4. gforce

    gforce New Member

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    20200725_164956.jpg 20200725_165014.jpg 20200725_165022.jpg Then I drew the wood parts in cad and printed out some templates to make 3 sets.
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  5. gforce

    gforce New Member

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    I used the paper template to make several of the support blocks.
    20200726_134700.jpg
    20200726_135458.jpg


    I screwed some cables to the sides of the paddles.
    20200726_180221.jpg



    ...and actuated them with my feet to get a feel for the forces in game.
    20200726_180621.jpg

    I've got 3 hinge locations as shown. Other than the hinges, everything else is the same.
    test.jpg
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  6. early_m

    early_m Active Member

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    My Motion Simulator:
    2DOF, 3DOF, Arduino, Motion platform
    I would think that a narrow section down the back focuses more on providing acceleration forces and wider for cornering forces. So I would imagine the 4" option would be somewhere in the middle of offering both.
  7. gforce

    gforce New Member

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    I did prefer the 4 inch option the most. With a close second being the 2 inch. I didnt like the 2 inch because of the sharp sensation when the paddles were relaxed (braking). I don't know how far back I will prefer the paddles to go when I'm braking hard but the 4 inch felt much better.

    The 7 inch surprised me how uncomfortable it was. I though it would portray good side loading but it just didn't feel right.
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  8. gforce

    gforce New Member

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    Now that I had a good idea on the hinge distance I wanted to get the seat molded tightly to my body. I want to build tactile into the chair so I started playing with the Dayton DAEX32EP-4 exciters that everybody in the tactile thread over at race department is raving about.

    My idea was to use these little rubber isolators to isolate the vibration from the frame of the chair so you're body feels the maximum energy from these little things. I built a quick test on aluminum.
    20200808_110805.jpg

    I was very happy to find the rubber does a great job of isolating the energy from the table. The exciters were not very impressive though and I wondered how much I would like them in the seat.

    It wasn't until I put some foam between the exciter and my arm that these things came alive!
    As it turns out, they move quite a bit when they are isolated from both the frame and the body. It is the act of the plate and exciters moving that give excellent vibration feedback. They need a suspension system.
  9. gforce

    gforce New Member

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    Working on the seat shape I was inspired like crazy by mike patey.

    So I built a chair to cast my body into.

    20200806_131936.jpg


    20200806_231736.jpg


    And used some 2 part expanding foam in a large trashbag to build a seat insert like they do in f1 (aside from the material).

    20200807_214057.jpg

    It took me several pours this being my first time playing with the foam. I was afraid it would get so hot from the chemical reaction that it would burn me. By the time I finished, I was using much bigger batches and while it was hot, it never burned.
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  10. gforce

    gforce New Member

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    Then I painted it matte gray and gave it some sharpie lines where it was too smooth in preparation for photogrammetry.

    20200808_120722.jpg

    20200808_120732.jpg

    I took about 45 pictures of the insert and tossed them into Meshroom - a free photogrammetry program.

    20200808_140315.jpg

    Once I had a mesh I poped it into rhino and modeled this seat from the shape of my body.

    20200808_211929.jpg

    Its a work in progress. Especially the bottom piece.
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  11. gforce

    gforce New Member

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    Armed with a 3d model I wanted to see what it would feel like. I was confident I would need to change something so I opted to machine it in foam to see it in person.

    20200809_133502.jpg

    20200809_133400.jpg


    This is an entire 4' x 8' x 2" sheet of insulation foam from home depot.
    20200809_144903.jpg


    20200809_162210.jpg

    Roughed out.
    20200809_170104.jpg


    20200809_171529.jpg


    20200809_173619.jpg


    Sweet.
    20200809_180345.jpg
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  12. gforce

    gforce New Member

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    The torso part feels great. I love it. Definitely fits right to the body. But the shoulder wings are too high.
    20200809_183832.jpg

    So I built a little cardboard container for some two part foam.
    20200811_135138.jpg

    20200811_135141.jpg

    Then I filled it with foam.
    20200811_154548.jpg

    ... and now I have material to shape for my shoulder.
    20200811_154859.jpg
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  13. gforce

    gforce New Member

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    This foam is really great stuff. Sands quickly, adding more is simple and fast, great for shaping. I bet anybody could make a custom seat for themselves without all the fancy cad and cnc just using this foam.

    20200813_085104.jpg

    I'm letting another 3d scan cook in meshroom for now.
  14. cfischer

    cfischer Active Member Gold Contributor

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    Ok been a couple of weeks since an update. A lot has happened.

    I didn't take a picture but I put down bondo on the foam and sanded it sort of smooth. Then I put box tape over all the surfaces to get a quick non stick surface. I thought this was going to take a long time but it only took a couple hours total and most of that was the bondo.

    I cut out 7 layers of fiberglass 5 12oz inside layers and 2 6oz outside layers.
    20200816_171523.jpg
    I then wet out each layer on the bench with a sheet of plastic behind and transferred it to the mold like a sticker.
    The black was sharpie that didn't get cut off all the way and bled all over.
    20200816_190010.jpg
    20200816_190019.jpg


    Then I put peel ply and poly batting over everything and stuck it in a huge trash bag.
    20200816_195831.jpg


    And let that cure overnight with the cheap amazon pump running all night. In the morning it got hot enough to blow nearly all the oil out all over the floor. This was with a high output fan blowing directly on the pump to try to keep it cool. I'm going to need to add a tank to this system so the pump runs intermittently.
    20200816_195845.jpg
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  15. cfischer

    cfischer Active Member Gold Contributor

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    The next day I pulled the part and trimmed and sanded the edges.
    20200819_150602.jpg

    After some careful measuring and marking I cut out the paddles. Not shown here is the nearly 4" strip removed from the middle.
    20200821_142505.jpg

    Then using some epoxy filler I blobbed some gussets into these aluminum brackets I made and taped it in place while it cured. This is after I sanded it a bunch. 20200821_142601.jpg

    These were created from some quick cardboard templates I came up with.
    20200821_114402.jpg


    This is where I will attach the actuator.
    20200821_114357.jpg
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  16. cfischer

    cfischer Active Member Gold Contributor

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    I have this shape available as a 3d scan for later in case I want to iterate or make individual paddle molds or something.
    20200903_164726.jpg


    20200903_164757.jpg


    Next it was time to take the peg leg rig apart. I need to use the actuators for now. The plan is to come up with the forces needed so I can size the motors and gearboxes that will be used in the end.
    20190909_081931.jpg

    20200818_113639.jpg

    I will use this looong 230mm travel actuators. It will look silly.
    20200903_164906.jpg


    I 3d printed some rod ends. Hope they hold up. The gseat is mostly loaded in compression.
    20200821_090549.jpg
  17. cfischer

    cfischer Active Member Gold Contributor

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    So then i whipped up a quick wooden frame to prototype in. The piano hinge was cheap stainless one off amazon. It has no backlash and is nice and stiff.
    20200824_174204.jpg

    2x4s in plywood can be changed around in seconds. Very nice for prototyping.
    20200824_174338.jpg

    20200825_124713.jpg

    20200825_124724.jpg

    20200825_124729.jpg

    Looong actuators installed. Plywood is clamped to 8020 frame for speed.
    20200825_185331.jpg

    One of the links to the paddles is a 250lb loadcell. This is so I can see the forces being applied and work out what motors/gearboxes to purchase from china. Don't want to wait the month of shipping twice.
    20200826_093211.jpg
    Load cell display.
    20200826_093218.jpg

    How do you like my g seat?
    20200825_185331.jpg
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  18. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    Now that will definitely have some kick, enough to bruise your ribs...I hope the kill switch is in easy reach ;)

    [​IMG]
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  19. cfischer

    cfischer Active Member Gold Contributor

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    My first impressions with this setup: I'm impressed.

    I spent some time setting everything up in flypt mover. I love that software.
    Got things going in dirt rally 2 and after a while of figuring out distance to move paddles and whatnot I am impressed. I drove several stages for fun, not trying to set records, but records were broken. It was kinda weird. It just felt really easy to drive. I had a similar experience going from screen to vr in dr2. I only have surge and sway mapped to the two paddles plus a belt tensioner pulling on all 4 belts (not pictured above). Its incredible how much feeling I get from the car. Just incredible.

    Surge is the easiest.
    The paddles clamp down on me when I accelerate. The belt slacks(cant really tell). I am pushing about 45 to 65 pounds on my body with each paddle during acceleration. This force is very nicely distributed from my hip to my shoulder. It is very convincing but there is a fundamental problem. My body moves forward during acceleration. It might only be an inch but I can tell and its just not right. No worries, I am planning on adding a torso seat mover for this very issue.

    The paddles open when I brake and the seat belts pull tight. I really notice the paddles opening since they are normally stuck so closely to my body. Its a very pleasing cue of slowing down. My belts pull pretty hard, something like 60lbs each. I have a lot of nuance while I'm not fully braking. For instance, I can really tell the car slows when I lift the throttle. I can feel it. I can feel hills slowing me down. There is a lot room for information when the max force is so high. Lots of resolution lets call it. Braking is much more pronounced than acceleration. I will say it again, the release of the close paddles really adds to the sensation of slowing down.

    Sway is harder but maybe more important.
    Rally driving is violent. I love it. Tons of getting tossed around, getting airborne, landing turned, digging into ruts etc. Its the best. And now I have feedback from motors strong enough to convey the violence. I turned the travel way up to get a good range and force for sway. Its currently something like 3 times more travel for sway than surge. The inside paddle opens a few percent then stops while the outside paddle squeezes your body over hard. I was getting about 130lbs max readings with surge. My body gets pushed to the side quite a bit. Like inches. I'll post a video later. This will need the seat mover to correct this dramatic miss cue. I end up with the most noticeable pressure on my shoulder from the bolster. This is why I get such a high force on the motor too since there is much longer lever arm at the shoulder that the motor has to overcome. Let me tell you, the subtle back and forth I get while adjusting my position on the road coming up to a turn is amazing. The mind instantly recognizes the cars motion and you have a deep connection. Then you get to the turn and there is a ton of range in the force to give you an idea of how traction is going, what camber you're dealing with, if you slide from gravel to tarmac you can feel the cars traction bite into the road as the chair shoves into your shoulder (and everything else but you notice the shoulder the most). It's bad ass.

    If I could only choose between what I have here and the 3dof pegleg sim I took apart, I would happily choose this very incomplete gseat. Chassis motion is by comparison, pretty stupid. You get WAY less information about what the car is doing. It's amazing to me that most motion in sim racing is chassis motion. I think that will naturally evolve to gseats over time as people learn more and more.

    I am more than pumped to get into the rest of the seat. I am ordering a huge pile of motors from china. So far the plan is seat mover and paddles on the torso. On the bucket I want paddles like the torso, whole bucket moves up and down for heave, forward backward for surge, and maybe side to side for traction loss or sway. I think that part will take more experimentation.

    While the motors from china are in route, I will be looking into tactile, foam cushion, and seat cooling.
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  20. cfischer

    cfischer Active Member Gold Contributor

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    You're right, I think there is enough power here to easily break ribs - like if the travel limits I put in software aren't respected. These motors had enough power to jump my several hundred pound rig off the ground. I'm not too concerned with safety for these prototypes (famous last words) but on the final rig I will be adding hard bump stops and a kevlar strap across the back so it cant crush you. As well as a kill switch.
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  21. cfischer

    cfischer Active Member Gold Contributor

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    I'm thinking about working on the sliding seat bucket for surge next. I have a feeling that this will be desirable but I don't know for sure. This will be an experiment. I won't be able to actuate the torso seat mover yet. Still waiting on the servos with planetary gearboxes from china.

    As the torso seat mover rotates back and the paddles clamp down during acceleration, the seat slider will move back. At the moment I am thinking I can compound the feedback by pushing the hips into the base of the torso portion as shown in red.
    Surge 1.gif


    Also an assumption is that the seat bucket should move straight back level with the chassis rather than up the 20° angle the seat bucket is set to.

    Surge 2.gif

    I'm going to have to iterate the crease of the seat. I'm thinking a fair amount of padding is in order.
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    Last edited: Sep 6, 2020