DIY VR DBOX STYLE 3DOF W/ 24V WHEEL CHAIR MOTORS

Hey Guys!

I am new here but recently got bitten by the sim racing bug and its hitting me hard!

I built a basic PVC sim rig after getting into VR a few weeks ago and it was a blast. The level of immersion the VR and force feedback bring to the table is just incredible. However, it instantly left me wanting more and I couldn't help but imagine the possibilities that a little more feedback could bring. I started researching motion rigs and was initially taken aback by the price, but after a bit more digging I came across DOF reality and the amazing systems they are offering. After watching Sim Racing Garages reviews on the seat mover, H2, and H3's I was surprised at how relatively straightforward the electronics seemed. A few more late nights researching and I came across this gold mine of a website!!

I am a mechanical engineer by trade with access to CNC mills, Swiss lathes, 3d printers, MIG welding and advanced CAD software so I have no concerns with tackling the design and manufacturing of the motion platform and with the help of this site I feel I now have a firm grasp on what is required from an electronics/software standpoint.

Initially I had intended on building a 3 axis rig similar to the DOF reality H3 with pitch, roll, and traction loss, but after digging through this site I realized what I really want is a 3 axis rig similar to a D-BOX with an actuator at each corner. Based on all footage I have seen this seems to give the best results for rapid oscillating style movements typically seen in automotive racing. I intend on exclusively using this rig for sim auto racing so I have little desire for long throw movement. If this works I will add traction loss and potentially surge in the future.

Every single 3 DOF rig I have seen with this style movement utilizes linear actuators, I do intend on building my own DIY linear actuators using the DC motors I have purchased in the future. But for now I would like to try making this rig work with the worm drive gearboxes that came with the motors I believe this is possible based on what I have seen from the awesome work from the guys at https://fasetech.com/ and their RC4 4DOF RacingCUBE . The teams early designs used what appear to be off the shelf DC motors with worm drive gearboxes.

Anyway, here is my B.O.M. :

PC:
Windows 10 Home Premium
Intel I7 2600k OC'd to 4.9 Ghz (needs upgrading TBH)
16gb 1666Mhz DDR3
Nvidia EVGA Geforce RTX 2080 Super XC-Ultra
2x Samsung SSD Evo 500 GB
1x Samsung SSD Evo 250 GB (OS)

Visuals:
Sharp Aquas 75" 4K (for spectators to watch, since rig is in living room)
Valve Index VR HMD (also have HTC Vive Pro W/ Wireless, but I prefer the index for racing sims)
7" LCD mounted to rig for games that don't support VR menus *cough* Assetto Corsa *cough*

Controls (for now, I intend on building my own pedals using a willwood pedal assembly and hydraulic pressure sensors with a guide I found on here) :
Thrustmaster T300RS Wheel
Thrustmaster T3PA Pro Pedals
Thrustmaster TH8a Shifter

Audio/Haptics:
Klipsch Promedia 5.1 Ultra surround sound
6x Dayton 'puck' bass shakers w/ 3x 50w amp boards, 12v 20 amp LED PSU and usb sound card

Motion:
4x 24v 250w wheelchair motors purchased on eBay
2x 24v 30 amp LED PSU's
2x Sabertooth 2x32 motor control boards
2x Arduino Uno's
4x 10k ohm potentiometers (currently got some el cheapo's coming from amazon, I need suggestions on where to purchase nice contact-less hall effect potentiometers in the states)

Chassis:
Welded steel with NRG racing FRP-300 fiberglass bucket seat and Tanaka 4pt harness.

Sim Software:
Assetto Corsa
Project Cars 2
iRacing

Motion Software:
SimTools
Arduino SMC3-SPS sketch
Sim Racing Studio (for bass shaker haptics)

I have everything listed on the BOM and received my motors yesterday so I can finally start working on the CAD model for the frame. Hopefully I will have something for you guys to take a look at before the end of the weekend!


Muh PC.... I like RGB Haha

I would definitely recommend the Index over the Vive Pro if you can get your hands on one, image quality is noticeably better IMO.

Initial PVC build using an old seat out of my Mustang. The PVC is great to work with when getting initial dimensions to determine what 'felt' best for me.



NRG FRP-300 seat and Tanaka 4Pt Harness (you know, so I don't get thrown through a virtual windshield HaHa), great deal on amazon. I will be adding extra foam to the lumbar area and seat pad when I embed the Dayton shakers. Another nice thing about the PVC is how easy it is to disassembly when mocking things up!


Dayton shakers, I have mocked these up in the seat and using the Sim Racing Studio software after some tuning the haptic feedback is pretty dang awesome. I am running two in the front of the seat wired to FR and FL channels, two in the back of the seat wired to RR and RL. I also have two under the pedals wired to FR and FL as well as a pair under the seat buttkicker style wired to SUB. I got the idea for this from Sim Racing Studio's ShakeSeat and ShakePedals. They seem to be a great over the counter solution for this kind of haptic feedback! https://www.simracingstudio.com/product-page/srs-shakekit-shakeseat-integrated-with-shakebox-lite

4x 250w continues 1050w peak 24v DC Motors w/ Worm drive gearboxes

All the other goodies, minus those dang potentiometers.

Thank you for the words of encouragement @noorbeast. I've already read through most information in the FAQ but I do appreciate the link.

Unfortunately work deadlines reared there ugly head and I wasn't able to get as much done with the simulator as I would have liked, but I did manage to squeeze in some tinker time this weekend.

My Amazon potentiometers showed up early so I got to wiring everything up in a test capacity.


The Sabertooth 2x32 supply's a return current to the power supply via regenerative breaking. When using a PSU rather than a battery you must create a voltage clamp with appropriately sized resistors to dissipate this current. My local Fry's electronics did not have nearly large enough resistors to create the appropriate circuit to dissipate the motors regenerative current. Per the convenient calculator provided by dimension engineering I determined I would need a 1x 200w 3 ohm resistor per motor.

Resistor Calculator:
https://www.dimensionengineering.com/calculators/power-resistor

200W 3 Ohm resistors are relatively expensive at around $20 USD each on eBay. I found a great deal on eBay for 18 100w 6 ohm resistors for only $30 USD shipped! I intend on wiring two each per motor in parallel to create the appropriate 200w 3 ohm circuits.

I used the amazing guide provided by BlazinH to wire and configure both the arduino's and Sabertooths. Following his guide made this so easy I would honestly say its barely DIY for the electronics and programming. Its just so simple!

BlazinH's Arduino and Sabertooth guide:
https://www.xsimulator.net/communit...ket-serial-pid-motor-driver-w-softstart.9277/

After some tinkering I was able to get all 4 motors working within Simtools on individual axis and DOF's. After playing with this program some more I can really see the power this software has. I was so happy with its performance and intuitive programming I went ahead a purchased myself a pro license! I realize I can get a free DIY license once I complete this build but honestly I just wanted to support the guys that wrote this game changing software, without it my sim rig dreams would be going nowhere!

Finally, I spent a small amount of time dreaming up some concepts for the cockpit. Using the dimensions from my PVC rig I mocked up these 3 concepts. I don't necessarily like/dislike any of them but none will be the final design. I'll probably go through quite a few more concepts before I land on something I like. Since this rig will be in the living room aesthetics are important, I'm drawing on the Vesaro and Next Level Racing rigs for inspiration. While these are just early concepts of the seat and wheel/pedal base frame I though I would post them encase anyone can draw some inspiration from the designs. They are based around 1x1 and 2x1 steel stock I happen to have laying around in my shop.