Showroom Compact, Budget 6-ish DOF g-seat with integrated motion using office chair and RC servos

Since the rig has become more than what I originally set it out to be, I decided to to start a new thread. The original thread can be found here: https://www.xsimulator.net/communit...ct-for-beginners-no-power-tools-needed.15307/

To summarize from the previous thread, both my knowledge of electronics and my DIY skills are pretty limited. I started off using 60 kg rc servos for air wedges on the gseat. Because these servos are so easily plug and play (only a few wires and they're up and running), I've since found all sorts of other use cases for them. The rc servos, while very weak compared to most other motors, still pack a big punch in a small package.

My approach has been:
1) Leverage the driver's weight as much as possible. For example, the driver is used as a compression spring for the surge movement. By placing my feet on pedals attached to a dolly, which itself is ziptied to the chair, when the dolly/chair is pulled forward and backward on surge, the driver's legs remove all the slack. This means that when you brake and the chair moves forward an inch, you feel pressure in your legs. (You also feel it in your hands since the steering wheel is stationary.) The driver also gets thrown back into the seat when it slides back an inch during acceleration.

2) Use the seat belts to drive some aspects of motion. The hip belts are connected to servos on the pedestal, so when the servos pull, the chair spins in that direction. In addition, per the latest update, the shoulder belts are now connected to a servo on the far back of the pedestal, which pitches the chair backwards. As for the new sway side paddles, the driver's weight holds them down.

3) Use as little hardware, tools, and materials as possible. No power tools have been used except a drill. Materials include 1.5"x0.75" lumber (perfect size for attaching servos), a dolly for the pedals, some metal plates, drawer slides used as linear sliders, a bit of plywood, plenty of zipties, furniture rollers, and the office chair/wheelstand itself. I chose an office chair since it already had built-in potential for 5 dof: surge, sway, yaw, pitch, and heave. (I haven't yet tapped into the heave functionality of the office chair and use other mechanisms to simulate heave. However, I am curious as to ways to implement true heave in the future.)

Currently there are 5 servos on the seat belt (2 connecting the hip belts to the pedestal for spinning the chair, 2 connecting to the ribs to simulate roll, and 1 pulling the shoulders for pitch); 4 servos for the g-seat air wedges; 1 for a g-headband to simulate accelation; 2 servos pushing chair and dolly forward/backwards; 1 servo for spinning the wheelstand on traction loss; 1 servo for sliding the chair sideways for traction loss; 1 servo moving the lumbar support sideways on traction loss; 1 servo moving seat back up and down; and 2 servos for side paddles (one on each side).

TLDR: Building on my previous version, I've implemented 5 additions:

1) Added metal side paddles for g-seat sway
2) Added pitch by connecting shoulder seat belt straps to back of chair pedestal
3) Raise/lower seat back cushion for sustained heave (ie hilly terrain, freefall, bottoming out)
4) Move lumbar support sideways for sustained traction loss
5) Added pitch to the pedal tray for flight sims

Here's a quick video of the sim in action (apologies for the lack of cable management, that's next on the list):


1) Added metal side paddles for g-seat sway
I took some 1.5" x0.75" wood and built a thin frame over the sides and top of the seat, then attached 7"x3" metal plates to squeeze the ribs. Using @007's trick (https://www.xsimulator.net/community/threads/007-g-seat-ultra-compact-servo-based.10470/#post-135388), a servo with a wheel pushes the plate forward on sway. (At rest, the user's weight keeps it in place.) While a single 60kg servo isn't powerful enough for positioning under/against the back ala the Simxperience GS-5, it's plenty powerful for rib squeezes from the side. Previously, the air wedges were not bad for sway, but it was really hard to position them so that they applied side pressure. Using plates for sway really changes that. I covered the plates with elbow rest cushions with memory foam to soften the squeeze.


2) Added pitch by connecting shoulder seat belt straps to chair pedestal.
I attached another length of 1.5"x0.75" wood to the back of the chair pedestal with a servo at the end, and I connected the shoulder straps to the servo.
The chair has an adjustable rocking/reclining feature with springs, and I loosened the rocking to 100%. I keep the seat a little too close to the pedals, so that when I sit in position, the chair will naturally recline just a bit to get into a comfortable position. Then I tighten the shoulder straps to keep the position, furthering the idea using the driver's body as a compression spring. This means that when you accelerate, you get sucked into the chair, and when you brake you get tossed forward. The pressure on the shoulders is actually minimal; just enough that you feel a small pull on acceleration. Some might prefer to feel the pull on braking instead, but I like how it contributes to the feeling of getting sucked into the seat.
https://youtube.com/shorts/Zhb-P5Lm2S0?feature=share

3) Raise/lower seat back cushion for sustained heave (ie freefall, hilly terrain)
Inspired by @MarkusB's heave elevator (https://www.xsimulator.net/community/threads/my-3-dof-motion-enhanced-g-seat.14950/), I placed a servo behind some plywood, which moves the seat back up and down. When falling downward, the seat back slides upward 1 inch to simulate rising out of your seat during freefall, and pushes downward so that you sink into the seat when bottoming out. Two air wedges placed on the seat also help accentuate the feeling of rising and sinking. Adding some cushion and two other surge air wedges over the plywood backing makes a decent enough cushion for now. I'm really surprised how well this simulates hilly terrain.
https://youtube.com/shorts/TDSfA6NXpV8?feature=share

4) Move lumbar support sideways for sustained traction loss
With the same idea for sustained heave, I added sustained traction loss. Using a 14 inch drawer slide connected to a small piece of plywood, I added a lumbar support that moves sideways one inch in either directly for traction loss. It's a simple trick, but it has helped to maintained sustained traction loss and better catch slides. Previously, I mostly just felt the onset of traction loss since the back of the chair was only sliding an inch in either direction.


Here's a picture of the back of the frame, which is velcroed to the actual chair:


5) Added pitch to the pedal tray for flight sims
I've also experimented with giving pitch and roll to the pedal tray. It gives a bit too much flex for driving, but seems to work well enough for flight. During racing, I keep the pedals in place with some 2"x4"s, and then remove them for flight.

Here's the my latest configuration for racing:
Acceleration
1) Shoulder straps tighten slightly and seat pitches back
2) Chair and pedals slide backwards
3) Back seat airbags inflate
4) G-headband pulls back

Braking
1) Shoulder straps loosen and seat pitches forward
2) Chair and pedals slide forward, wheelstand is stationery so more pressure on hands/arms
Cornering
1) Side plate pushes against rib on opposite side of turn
2) Servo attached to pedestal pulls hip belt (on opposite side of turn), causing chair to spin and mild pressure on hip
2) Rib belt pulls slightly downward on opposite side of turn

Heave
1) Seat back cushion goes up and down to simulate hilly terrain
2) Air bags on seat bottom inflate
2) 30% of chair sliding forward and backward to simulate heave for kerbs, grass, etc.
3) 30% of shoulder strap pitch forward and backward to simulate heave for kerbs, grass, etc.

Traction loss
1) Lumbar support moves sideways
2) Rear seat wheels are pulled sideways
3) Wheel stand spins
4) Rib belt pulls down to one side (g-seat version of roll)
And here's the latest list of motion for flight:

Here's the latest list of motion for flight:

Pitch/Heave (combined because currently using Joystick plugin)
1) Shoulder straps tighten slightly and seat pitches forward/back
2) Seat back cushion goes up and down to simulate heave
3) Airbags under calves and on lumbar support inflate
4) Pedal plate pitches forward/back

Roll
1) Hip seat belt strap pulls on side of roll
2) Chair slides to opposite side of roll
3) lumbar support slides to opposite side of roll
4) Pedal tray rolls to one side

Acceleration
1) Shoulder straps tighten slightly and seat pitches back (only 20%)
2) Chair and pedals slide backwards
3) Back seat airbags inflate
4) G-headband pulls back

Braking
1) Shoulder straps loosen and seat pitches forward (only 20%)
2) Chair and pedals slide forward, wheelstand is stationery so more pressure on hands/arms
Yaw
1) Side plate pushes against rib on opposite side of turn
2) Servo attached to pedestal pulls hip belt (on opposite side of turn), causing chair to spin and mild pressure on hip

I'm seriously considering building this, how many hours do you think it would take?

Hi @miketunes! Thanks for your interest in my thread! The most time intensive part for me was the R&D. For better or worse, I only used 60KG servos, so while they are rather limited in their power, they are really easy to repurpose and have a variety of uses, not to mention that they move really quick. Basically, because of their limitations, it took me a while to dream up new use cases through trial and error. However, the use cases themselves are pretty simple to apply.

Since these servos are so easy to implement, and I only use simple materials (zipties, plywood, 1x2 lumber, drawer slides, etc.), it would only take a few days to implement. Depending on which aspects you decide to implement, you might be able to copy the bulk of the project in a weekend. For example, the seat belt tensioner/chair spin can be set up in like an hour, maybe a little more if some trial and error is needed to find the optimal position on the seat. The g-headband can be implemented in 15 minutes. There are a lot of moving parts (probably over-engineered), but I had fun dreaming up new applications. In fact the most difficult part may actually be wiring/cable management. Since each component can work independently, you can pick and choose which ones work for you, and even find new use cases that I haven't thought of.

In case it helps, I've also added a few more components that I haven't had the chance to post about yet. These include:
1) I've updated the g-headband to also pull side to side to feel lateral g-force in the neck muscles
2) I've added a servo that pulls the legs downward on breaking
3) I added a drawer slide to move sideways the part of the seat that touches the shoulders

In any case, let me know if you have additional questions, and keep me posted on your progress! Best of luck!

Is the parts list from your 1st post accurate, or what should I add for the more recent changes? I'll probably do everything you like - gheadband, leg servo, ect.

I think it's pretty accurate, and most of the major items should be listed, although I can't say for certain. I don't think I described the screws, bolts, etc., but all that can be easily improvised. I've repurposed some of the parts as the project evolved, so you may need to follow along with the progression, but that shouldn't be difficult. I've also added a few bits here and there to increase stability, which might be completely posted. In addition, you'll need to find the right dimensions for the components so that the project fits your body type and preferences. As you progress, you may need to adapt, but that's the fun part of DIY; you get to make it uniquely yours.

Ok, mind if I keep posting here as I have questions. Do I need 16 total Servos?

• 5 servos on the seat belt
  
  
• 4 servos for the g-seat air wedges
  
  
• 1 g-headband
  
  
• 2 push char and dolly forward/back
  
  
• 1 lumbar support sideways
  
  
• 1 moving up and down
  
  
• 2 for side paddles
  

Hi @miketunes, sure thing; please continue to post any questions here. Happy to provide answers.

Currently I'm using a total of 20 servos:
In addition to the 16 you mentioned, I also have:

• 1 servo between the rear wheels for traction loss (not sure if the added complexity was worth it for this servo)
• 1 servo spinning the wheelstand for traction loss (not sure if the added complexity was worth it for this servo)
• 1 servo attached to the top of the seat to move the shoulders sideways (same idea as the lumbar support)
• 1 servo connected to the bottom of the seat to pull downward on a separate belt around the thighs to better feel brake g-force (I haven't updated the thread to show this)

Note that the first two traction loss servos that I mention earlier in this post are probably the most over-engineered part of the project. While it's been a fun exercise to design it, it was a pain to get it to work, and it only adds marginal gains. What makes it difficult is that the sideways movement has to work in conjunction with the forward/backways movement.

To solve this, I added furniture sliders to the back wheels and connected them to drawer slides, which then made the back wheels higher than the front wheels, and so I had to level everything out. By cutting out these 2 servos, I feel like the complexity of the project is reduced by 75%. All of the other parts play together really nicely. I recommend building everything else first and only adding these 2 servos if you still feel like something is still missing.

Yeah I'll skip those last two. So I'll need 18 ac adapters too, or is there something more efficient that will allow me to power them more from a single box or two? How does changing from 6v to 7.5volts effect things?

I started out with just the air wedge g-seats and kept building upon that, so I used a separate AC adapter for each servo, and kept building up from there. I used these:

Someone with a better knowledge of electronics would probably use a single power source, but this is what worked for me.

7.5v seems like the sweet spot for these servos, so it gives a bit more power over 6v.

Does 180 or 270 degree matter? I was looking at these?
https://www.aliexpress.us/item/3256...045454!&curPageLogUid=Hxx0jfvPAXjL#nav-review

I think I will buy 18 adapters, do you know how I figure out how much wattage or amps those servos will draw? Is 45 watt the minimum or just what you used.

Do you mind linking the power adapters you used? It looks like 45 watt adapters usually max out at 3amps. Most of the 60k servos seem to want up to 6.2amps.

180 or 270 degrees doesn't matter much, although I prefer 270. 180 degree is slightly easier to program, whereas 270 gives much more flexibility. This is because the arduino library uses integers from 0 to 180 for servo position; when using a 270 degree servo, that same 0 to 180 arduino code, in actuality, scales the servo from 0 to 270. However, these servos seem to be few degrees below the advertised rotation, so 180 degrees is really like 175 degrees. Hence, you might have to tinker a bit more with the settings for the 270 servos, but you get more flexibility.

As for wattage/amps, I'm not sure how much power they draw. I've never tripped a circuit breaker yet with my setup. However, I'm not very skilled in electronics, and this was my first foray into DIY, so please keep in mind that these are the ramblings of an absolute amateur, lol.

Here's a link to the adapter that I used, which apparently is 45 watts: amazon.com/gp/product/B01MT5WVCG

One last thing...18 servos + 18 adapters can be a bit pricey and a big investment all at once. If you're definitely all in, then go for it; but if not, there's no harm in buying 3 or 4 servos and doing the super easy stuff like g-headband, seat belt tensioner, etc. so that you get familiar with the servos and what they can/can't do before taking the full plunge...just my 2 cents. Also, these servos are very chirpy, so make sure that the noise levels are acceptable for you. I'd hate to see you buy all that stuff, and then as you get more familiar with the project, decide that a better setup might be possible with different components.

One more "one last thing" lol, if you don't have a chair in mind already, I'd recommend buying one that has has a reclining function so that you can use the reclining for pitch via the shoulder seat belt straps. Here's the one that I used for reference: amazon.com/gp/product/B07D4LV9GY

*posted edited to show links to Amazon. For some reason they weren't showing up originally.

Yeah it's getting a bit above the original $500 mark, but that's before all your enhancements. I like your idea of starting a bit more simple. What should I remove from the order parts list to just get the basics you talked about? Or should I just order everything except less servos and power adapters?

I'd order less servos and power adapters. I'd also skip on the air wedges for now and focus only on the belts, since these will give you the biggest ROI. If I were in your shoes, I'd focus on the items in this order:

1. If your chair has a recline spring function, take advantage of that for pitch. Connect a servo to some 1x2 lumber (lumber attached to back of chair pedestal) and connect the shoulder seat belt straps to it. I only needed one servo, but it might require 2 depending on the power and your weight. For reference, I'm 5'7'' 160 lbs. and one servo seems to work well with my setup, but it might benefit with a second servo. (Start with one and add a second if needed.) This pitch also helps to give a g-seat feeling if you use it for surge since the shoulder seat belt straps will tighten slightly pulling you into the seat. Some people feel that the shoulder belts should tighten for braking, but I find that it feels better for squishing me into the seat during acceleration. I feel like there are other ways to represent braking.
2. Connect each hip seat belt strap to to a servo on either a) the chair pedestal for chair spin + seat belt tensioner or b) to the chair arms for just seat belt tensioner and no spin.
3. G-headband. If you do this, make sure you have an elastic headband! The purpose of the g-headband is to engage the neck muscles, not to cause whiplash. The elastic headband will add an increasing pull but won't whip your head band. If you're in the US, I picked up some elastic headbands from Dollar Tree.
4. Connect a separate servo to the bottom of the seat and have it pull a separate belt around your thighs for braking.
5. Lumbar support lateral movement to represent traction loss. This is where you'll have to start to really get DIYing. You'll need to build a simple frame or something on the seat to move the lumbar support sideways.

Note that I used a simple 4 point harness for my project since it was already elaborate and I only wanted to have to buckle only once. (5 or 6 point harness may require buckling in each harness). A 4 point harness can ride up a little sometimes, but I prefer the simplicity and cheap price. I think I picked up mine for like USD $30. However, you might be able to think up more uses with 6 point harness.

For now, I'd also skip on the air wedges. While they air wedges are nice, they can be a bit annoying because you constantly have to refill the air. They can be an easy way to add some heave, but you'll need to buy air wedges, hinges, hoses, and connectors, which can add some complexity. The wedges work well, but if I had to choose between belts and wedges, I'd definitely choose the belts; belts are much simpler to add, easier to configure, and give a stronger feeling than the air wedges.

As for the remaining components of the project, you can always add them later. Nothing interferes with anything else except the forward/backward slide and the traction loss rear slide. Implementing one of these isn't too much of a challenge, but implementing both adds some complexity. Nothing that can't be surmounted, but get it working first and then decide where to go. As you get more familiar, you may find other/better uses than what I came up with.

TLDR: if you just want to get your toes wet, you can just buy a single servo and power adapter, and get familiar with that. If you're more invested and up for a nice starter project, I'd get 5 or 6 servos and power adapters and work on the items listed above. This would get you 80% of the benefits for only 20% of the effort; you'd get some good g-force simulation and remain under budget. If you're absolutely all-in and want to completely recreate my project, you can get all 18 servos and adapters. However, there's nothing preventing you from getting a few servos and slowly building up, since most components work independent of the others.

I forgot to mention that you should also get some M3 eye hooks to put into the servo arms and then attach to the seat belt via heavy duty zip ties: amazon.com/gp/product/B08F7S6H9F

Thanks.. trying to get my shopping list together. I think this is what you said I should order to start out with?
Chair w/ reclining spring
1x2 lumber
shoulder seat belt straps
Servos - 5-6
hip belt straps
elastic headbands from dollar tree
4 or 6 point harness
m3 eye hooks
heavy duty zip ties


Or is that in addition to everything below- or wasn't sure what to take off this list except for the additional servos/power/and air wedges.

Two 13x13x11 heavy duty plastic milk crates (one for the device, and another to store the seat cushion on top) https://www.homedepot.com/p/GSC-Tec...orage-Tote-in-Graphite-STMC13131115/306330052
Five 60 KG servo motors (four for g-seat, one for office chair spin)
Five “45W Universal 5V 6V 7.5V 9V 12V 13.5V 15V AC DC Adapter Power Supply”. I chose ones with a small plug (rather than a large wall wart) to save space when connecting to the wall. I’m currently running them at 6 volts, but I like the ability to change to 7.5 volts if desired.
Four 10x10 inch zinc plated hinges https://www.homedepot.com/p/Everbil...Plated-Heavy-Duty-Strap-Hinge-15406/202034149
Arduino board (I used a Mega 2560, but really an Uno would work just as well)
Four 11x4 inch air wedge bladders for seat https://www.ebay.com/p/4011529979?i...OGIY3AkWtWYWj-qi2p_2ObJDRScAiedxoCFbMQAvD_BwE
Four 6x6 inch air wedge bladders connected to servo/hinge
15 feet of cable 5mm (3/16 Inch) inner diameter high performance silicone vacuum hose line (for connecting servo air bladder to seat air bladder). FYI I recommend getting 20 feet .
Four 5mm (3/6 inch) nylon tee vacuum connector (one for each pair of air bladders)
11 inch male-to-male dupont wires
Three 3x7 inch galvanized plates for attaching servo for office chair spin as well as office chair caster wheel stoppers https://www.homedepot.com/p/Simpson...X-Galvanized-Heavy-Tie-Plate-HTP37Z/202329565
One 8 inch zinc-plated corner brace for connecting office chair to servo for spin https://www.homedepot.com/p/Everbilt-8-in-Zinc-Plated-Corner-Brace-15215/202033926
Two 4 inch zinc-plated corner braces for attaching three 3x7 galvanized plates to milk crate https://www.homedepot.com/p/Everbilt-4-in-Zinc-Plated-Corner-Brace-2-Pack-15309/202033899
Four 3 inch zinc-plated corner braces as a safety stopper in case the zip ties ever break https://www.homedepot.com/p/Everbilt-3-in-Zinc-Plated-Corner-Brace-4-Pack-15307/202033902
Two 2 inch zinc-plated corner braces for connecting chair spinning servo to three 3x7 inch galvanized plates https://www.homedepot.com/p/Everbilt-2-in-Steel-Zinc-Plated-Corner-Brace-4-Pack-13611/203170052
Two silicone caster wheel stoppers (I like the ones with a dip in the middle to prevent any kind of wheel slide
RC camber linkage rod (to attach to servo to extend arm for office chair spin)
One 8.75x6.25 inch plastic cutting board (for attaching 8 inch corner brace to chair for spin https://www.ikea.com/us/en/p/ikea-3...BoL05uw65uQg4nvwYifua1BKS4xTnE3BoCcWYQAvD_BwE
Old to-go food container for propping up wires and Arduino (in case anyone ever spills something on the floor)
Reusable plastic bag for base of g-seat
Two foam pool noodles (for side support) (https://www.walmart.com/ip/SwimWays...epjABOXCfyksCRDTJh-NY6jXVfhCnTHxoChoEQAvD_BwE
Velcro strips to position air bladders to seat via reusable plastic bag
Velcro wire tie for connecting 8 inch corner brace to servo for spinning chair
Duct tape for connecting foam pool noodles to reusable plastic bag
Electric tape
4 inch 8.2KGF zip ties for servo arms (I then used the 11 inch 22.6 KGF zip ties to connect to hinge) (https://www.homedepot.com/p/Commercial-Electric-4-in-UV-Cable-Tie-Black-100-Pack-GT-100MCB/203531918)
14 inch zip ties for securing cutting board to seat
11 inch 22.6 KGF zip ties for connecting hinges to milk crate and 4 inch zip tie to hinge. (https://www.homedepot.com/p/Commerc...able-Tie-Black-20-Pack-GT-280STB-20/300645008)

I think you can skip most of the items on the list. You'll still need:

1) Arduino card
2) Breadboard
3) Wires
4) adjustable cord to connect servo to g-headband. I used this: https://www.homedepot.com/p/ProGrip...-Particle-Rope-Lock-Paracord-055160/206957471

Also just an FYI, hip and shoulder seatbelt are usually one single piece.

Few more questions on the shopping list.
M3 Eye hooks - how many - will these work?
Zip Ties - do I need a certain strength rating or number, will these work?
Arduino kit - will this work or do I need more wiring?

Here's the rest of my shopping list if there's anything else I'm missing:
Chair w/ recline
https://www.ebay.com/itm/394856877185
1x2 lumber
https://www.homedepot.com/b/Lumber-Composites-Dimensional-Lumber/1x2/N-5yc1vZc3tcZ1z0ywxz
Servo - 5 (270)
https://www.aliexpress.us/item/3256804747183904.html
power adapters - 5
amazon.com/gp/product/B01MT5WVCG
elastic headbands from dollar tree
https://www.ebay.com/itm/394848837421
4 or 6 point harness
https://www.ebay.com/itm/152367745958
adjustable cord to connect servo to g-headband
https://www.homedepot.com/p/ProGrip...-Particle-Rope-Lock-Paracord-055160/206957471

Hi, I'm not seeing a link to the Arduino, but I'd advise a new person to get a genuine Arduino Uno or Mega card, and not a clone. (The clones are a bit cheaper but require extra preparations to get to work.)

You'll need one eye hook per servo, but it can't hurt to have some backups in case the threads get worn down.

Otherwise, I think most of your shopping list looks good with the exception of the chair. I'd recommend a racing gaming chair (with rocking / reclining function), something like this:
Homall Gaming Chair, Office Chair High Back Computer Chair Leather Desk Chair Racing Executive Ergonomic Adjustable Swivel Task Chair with Headrest and Lumbar Support (White) https://a.co/d/b4oGBmr

A chair like this will have slots for the seat belt behind the shoulder and hips.

Oh and for zipties, mine are rated for 22.6 kgf. Depending on how you use them, they may break over time, but they are cheap and easy to replace.