G-SEAT

cfischer9009 · Sep 6, 2020

Hi guys, I started a thread on xsimulator to document my G-Seat project and I figured I would share it here too.

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, @Tronicgr_6DOF aka Thanos, seattime, yobuddy, @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 peg leg 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 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.

cfischer9009 · Sep 6, 2020

Currently I have made fiberglass paddles that are molded from my body so they fit tightly. I also did a study on the hinge separation as documented on xsim if you want to see that. I settled on 4" center to center for the paddle hinges.

The seat pan currently is rigid expanded poly foam cast around my body. Not bad for a comfortable seat insert. It will change over time.

I made a quick plywood frame to prototype in. I will be doing many iterations of things to learn how to make the best g-seat that I can. Wood is super quick for making changes.

While I wait on more Chinese servos I have taken my peg leg rig apart to use the actuators. They are 230mm travel and use the more powerful/longer 80st-m04025 motors so they look a bit silly hanging out the back right now.

One of the links to the paddles is a 250lb load cell so I can understand what kind of forces are required by the motors. This way I can size the motors and planetary gearboxes appropriately.

Read out of the loadcell.

cfischer9009 · Sep 6, 2020

I've spent a few hours driving with this rudimentary setup, mostly in dirt rally 2.
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.

cfischer9009 · Sep 6, 2020

My next task is to understand the sliding surge seat bucket.
The torso will have the two paddles as well as a seat mover setup as shown below. I don't have the motors yet to implement this so I will be moving on to the sliding seat bucket for surge.

I have this crazy idea that I can slide the seat bucket into the base of the seat back to give a stronger cue of surge. I don't know if this will work but I'm going to try.
It will look something like this.

Try to imagine the red region is some kind of cushion that makes this work. I'm not interested in making something that totally sucks so try not to let your mind go there.

Neilski · Sep 6, 2020

Looks great!
For some reason, the safety concerns for this seem more prominent in my mind than for a normal motion rig (where you're just riding on top of a rigid structure. If both servos push at maximum power at the same time, can it hurt you?

(PS: which software did you use to produce the cool animations?)

cfischer9009 · Sep 6, 2020

Currently there are only software limits keeping it from crushing me. When this grows up from the prototype stage i will have several things in place to ensure safety like hard bump stops, collapsable links, and a kevlar strap across the back to limit max squeeze.

I spent a chunk of time yesterday learning how to make those animations in blender. I normally use rhino for cad and its lacking in mechanism capability. Been wanting to learn blender for quite some time as its so powerful, free, and here to stay.

Neilski · Sep 8, 2020

Sounds good!
And yeah, Blender is great, but omfg the UI... just can't get my head around it. I've used many different image editing packages and CAD packages in my time, and they all "make sense" to me after some kind of learning curve. I really want to harness Blender but the UI keeps driving me nuts and putting me off

cfischer9009 · Sep 8, 2020

Neilski said:
Sounds good!
And yeah, Blender is great, but omfg the UI... just can't get my head around it. I've used many different image editing packages and CAD packages in my time, and they all "make sense" to me after some kind of learning curve. I really want to harness Blender but the UI keeps driving me nuts and putting me off

I highly recommend giving them another try since as of 2.8 and now 2.9 they have made much efforts in user friendlyness. Also i think i would give up in frustration if i didnt set blender up with left mouse button select and right mouse button navigation.

Right-Click Navigation (WIP)

I like to set up Blender to use the right mouse button for navigation, instead of using middle mouse. This is no small undertaking, so I decided to clean up my 2.8 config and share it as an add-on for anyone else who wanted to use it: Right-Click Navigation. I’ve seen a few similar keymaps...

blenderartists.org

cfischer9009 · Sep 17, 2020

The seat bucket surge turned out better than I had hoped. The feeling is fantastic.
By the way, all the audio you hear in the video is coming from 8 exciters playing game audio really loudly. Great engine tactile!

Neilski · Sep 17, 2020

Simply awesome! (How many ribs did you break in the crash at the end?

)

cfischer9009 · Sep 18, 2020

Thanks! The crash forces don't come through. The most force I feel is like second gear in a hard turn with lots of traction. You can see the forces on the load cell with the red readout on the cart next to me. Those are in pounds and show exactly what the motor is seeing through the linkage.

Usual races max out at 100-130 lbs (using the max readout setting). The max I've ever had so far is 200lbs (it just felt like a wild ride - Porsche 911 Germany Dirt Rally 2). Remember that force is distributed across my entire torso and shoulder, with the shoulder part of the seat having a longer lever arm.

I have yet to feel anything that had me spooked. On the contrary its easy to forget about the seat and concentrate on the driving. You really start to feel "present" in the car.

cfischer9009 · Sep 21, 2020

So a couple of pics from before.

I needed to convert my push only actuator into push pull.
So I milled some brackets and welded them on to the steel rod.

Worked great!

Printed a cylinder to flip the ball nut on the screw without loosing balls.

Some assembly and this actuator is all set.

I drilled a hole in the steel rod and bolted on this bracket. Now I can screw this down to the wood on the seat bucket.

cfischer9009 · Sep 21, 2020

Got my seat bucket wood mounted to a linear bearing.

Plywood board and seat pad go on top of these 2x4s as marked.

Here is that bracket I made for the steel rod. Kind of silly how small I made it. I used 3.5" long wood screws (predrilled) and it has survived pretty well.

I want this seat to be tried by many so I made the left hinge able to be adjusted. This has come in handy since the gseat has to be fit to each person to get the right feelings.

I can adjust the position of the stepper motors with a pot mounted to the rig. Sadly the little nema 17 motors will skip steps when moving if the body is relaxed in the seat. It will not skip steps when still so if you lean forward during an adjustment it works well.

Since this seat wraps around the body so far it really needs to be dialed to the person driving. This is a pain but I happily go through the work since the outcome is so excellent.

cfischer9009 · Sep 21, 2020

Since this seat has a lot of curvature i don't have good mounting options for the dayton daex32ep-4 exciters. So I jb welded these washers to the chair as they are a perfect fit.

In the video I posted above you can hear the exciters screaming all the game audio full spectrum through the seat. Feels great! I plan on diving deeper into tactile later. For now I just plugged in 4 4ohm exciters wired parallel and series(adds up to 4 ohm) into two HW-576 amps. One for each paddle. 8 exciters in total. Audio mirrored from the vive to the amps.

I really love hearing the different vehicles engine characteristics come through. As you can see I drive with headphones while the seat is screaming because they sound better than the seat with my body against it. The combo is excellent.

cfischer9009 · Sep 21, 2020

Next on the agenda is to add heave and traction loss to the seat bucket. Stay tuned.

cfischer9009 · Oct 3, 2020

cfischer9009 · Oct 30, 2020

Ok so as much as I am annoyed spending time showing you something I didn't use, I do think its cool to show failures or things that didn't work out in the name of learning. So hopefully somebody learns something from this.

I didn't like what I build, but I'm glad I tried it. If I didn't I would have always wondered.

Crank arms for the gearbox. I drilled and tapped a bolt right next to the key to clamp it to the shaft.

I made an aluminum spacer to hold the motor mount in place while welding.

cfischer9009 · Oct 30, 2020

If you want to see how the motion looks go to xsim and scroll down to the bottom of the post. I made gifs of the motion but RD is too cheap on its file sizes.

G-SEAT

The seat bucket surge turned out better than I had hoped. The feeling is fantastic. [MEDIA]

www.xsimulator.net

cfischer9009 · Oct 30, 2020

The simpler frame has mounts for two motors for thigh paddles. This was part of the plan all along but I left out the thigh paddles on the last attempt to keep it simpler.

You can see how everything goes together before the wood comes in.

So here are the thigh paddles. Again a prototype. They will be composite like the back paddles someday soon.
I really like the feel of the thigh paddles. They are super strong and bite down into your leg (rather than lift the leg as most seem to do) giving you lots of "resolution" of the force you're feeling.
Adding this really made the sim feel more "full bodied" and really made me wish a g helmet was already setup.
I'm sure a video will be along later.