My project 2DOF plus Traction loss

Hello,

After long hours of research and consideration I decided to start designing and building my own 2DOF + TL motion platform. Initially I planned to start big and go with a 6DOF, but research and the financial comitment made me rethink the whole project.

Once the project is finished I hope to have a platform I can use for driving mainly Rally and RallyCross with currently DirtRally2.0 and I am also looking forward to get my hands on WRC9.

With the planning so far, I will go with one display mounted to the rig itself, so that the display moves with the rig. At a later stage I plan to go VR, but currently I am not sure which headset to use.

My driving gear is a Thrustmaster TMX PRO, which I am pretty happy so far. I think it has a good price for value ratio, especially when you are able to get a very good price from your local shop.

The seat I plan to use, because I have it already is a used SAAS bucket seat, quite heavy but also quite comfortable.

Inspiration, ideas and "headaches" I found in the post from @noorbeast (https://www.xsimulator.net/community/threads/dx-compact-simulator.5866/)

I use:
Motors:
12V 200W DC with a 60:1 Worm Gear (3x)
(https://www.motiondynamics.com.au/worm-drive-motor-12v-24v-200w-180-rpm-20nm-torque.html)

Motor Controllers:
IBT-2 H-bridge (3x)
(available on AliExpress, eBay or Amazon or your local parts dealer, if you have one)

Power supplies:
12v 500W (3x)
(available on AliExpress, eBay or Amazon or your local parts dealer, if you have one)

Other electronic parts:
Potentiometer 10K linear (3x), Switches, Cables, ...

Important mechanical parts:
Heavy duty Universal Joint from an unknown 4x4, Low Profile Heavy Duty Rigid Caster Wheels (3x)

The rig will be welded together by a friend of mine, out of 25mm and 32mm aluminium round tubing.

Here are some pictures from rigs my mate Peter build already for himself and friends. These rigs are non-movable at the moment, but together we will work on modifications to make them movable too.

More pictures of hardware I intend to use for the rig, one is the drive shaft part with the two universal joints, it looks a little old, but is just surface rust. The joints themselves move easy, freely and without issues.
The other picture shows the rods this with the rod ends from a sprint car. The other item in the picture is a used steering system from a kart. The latter will be used for the traction loss movement, the other two for the 2DoF movements. At the moment the parts are a bit long, but this is not a problem with a good reliable saw.

Today I will post picture of my concept, I use Autodesk Fusion360 to make it. The drawing is not finished yet, so please see it as s work in progress design concept.
I planned to make it adaptable for different body heights, because my son is interested to use the simulator too.
The hight of the steering wheel is adjustable and the pedal stand is movable to and from the seat, to adapt to different leg length.
The rig itself will be movable along the longitudinal axis to align the centre of gravity of the rig with the user to the best possible position aka. over the u-joint.

Please let me know what you think and if you see potential issues, please also come forward, your help is much appreciated.

New

hello chrisgeo i'm also making mine with iron and you used aluminum, you have an idea of the total weight of the cockpit

Hello Fernando,

currently the overall weight is calculated to be around 5 to 6kg for just the frame.
The weight might go up a bit, if we have to attach more metal for stability purposes.
I will post the total empty weight here, once the frame is completely welded together.

I was a bit quiet in the last few days due to an issue with my back.
Nevertheless and thank to modern chemistry, I was able to almost finish the pre-wiring for my
test rig. As you can see in the picture it is messy and and not good looking at this stage. It is safe and can be used, but to make sure no-one get zapped, it will be covered by a perspex sheet and all the switches will be accessible from above the perspex sheet. When you start doing this I recommend that you get a good, adjustable wire stripper from the tool shop of your choice. I used heat shrink tubing for all soldered and some crimped connections, for safety and reliability reasons. Once the the rig is finished, all the cables will be wrapped in spiral tidy.

Missing in the pictures are the illuminated 240V switches for the AC connections to the power supplies, the 5V DC power supply for the IBT-2 and the Arduino, the 40x40mm fans for the IBT-2 and the IEC-C13 socket for the mains connection.

I had a bit of time in the last few days, to put a very quick and dirty test bed together. The idea behind is, to find failures and fix them before it goes to the fabrication of the frame.

I used 25mm MDF, I had over from another project I built recently, furthermore some basic cheap hardware I bought from our local hardware store. I tried to buy stuff I can use in the future for other things.


I experienced the following, building and setting up this thing:
I had to re-solder one of the potis, because it was turning in the wrong direction.
Hot glue does not like zinc coated bolts, I had to reapply the glue a few times to fix the potentiometers to the bolts I use. The hex-bolts will be replaced with proper stainless steel bars for the final rig, but for the test they are sufficient. The hot-glue will be replace with proper torque limiting couplings.


For the traction loss movement I used small rigid casters attached to the bottom of the plate in an angle to follow the movement.

The cabling is still very chaotic, but I learned I made the cables to short, and I will use a screw terminal shield for the Arduino to remove potential issues wit the cables coming loose.


Today I also received my Chinese made USB handbrake, I had no time to attach them to my computer to test, but the built quality is quite good. I will keep you updated how they work.


I will upload some videos of the motors moving to Youtube and attach the links to the post.
The tuning for the motors is not done yet, but they move and the rig did not catch fire and the main fuse did not trip.

Hello,

I am back after a longer than expected break due to a busted back.
Now with me slowly recovering, I am able to to work a bit on the simulator again.

The first aluminium welding (more tacking) is done, to undo the joints just in case. The main tubes are 32mm with a 25mm tube inside as a reinforcement.
I will use my Oculus Rift S for the setup, however the rig is also planned to accommodate up to 3 screens if necessary (I case I get sick while driving in VR).

Giving the weight of myself and the seat, I have to mount the universal joint pretty much straight under the seat for balance reasons. The position of the universal joint will be adjustable for multiple reasons such as, I am loosing weight (unlikely), going with displays rather than VR headset, lighter person is using the sim, ...

Today I received back the universal joint from the welder. The total height of the joint is 200mm. I think it is sturdy enough to hold even the heaviest person. I sourced it from a wrecker and the past it was a front drive shaft from a Landcruiser.

Here is a small picture of the way I think I will implement the traction loss.

Today was another day in the workshop to do something on the rig.
First we determined the centre of gravity, which will be used as the mounting point for the universal joint.





To mount the universal joint we use a 100x50 aluminium box, currently it is only tacked to the frame, in case it needs some changes.

Here are some detailed pictures of the seat mount. It is nice and sturdy, just in case I will change the seat to a different type in the future. The large cross member will also accommodate the butt kicker transducer.

Some funny pictures showing the maximum forward and backward (exaggerated) angle of the rig, The final movement range will be restricted to +-10deg, which will give a movement of 150mm in either direction (up and down). As you can see in my mates faces, the rig makes fun already.

Here is the link to a short video showing the rig. My mate is a bit lighter than me, therefore the balance is a bit off.

Just a short update, started to design the motor mounts. First on the computer and than on the real material. Otherwise I was a bit short of time recently.

To have a nice look and make it easier to install a the mechanics, I changed over the the orientation of the axis of motor, so both longer ends face outwards.

Another day in the workshop with building the motor mount. I decided to go with a boxed design for the motor mounts to give it enough strength and prevent unwanted deforming when in use. The other good thing is it nice to hide and protect the electronics in it.

I used today to upgrade my PC, because what is the best motion sim without proper content.

I had a few parts sitting in my desk, just waiting to be installed. Btw, my normal day-to-day computer is a Mac, therefor I had no need to install the parts more urgently.

Here is what I upgraded:

i9 9900KF for an i5
RTX 2080S for an ATI 570
32GB for 8GB
Corsair H115 for a stock fan
1TB NVME SSD for 256 GB Sata SSD
additional rear and front fan

With the hardware done, I will optimise and slightly over clocking the system in the next few days.

Today I received the seatbelt / racing harness and the geared motor for the SimSeat.
I will try the geared motor over a servo first, because the motor has a bit more torque and I can use
12V instead of 7.4V for proper servos.
The geared motor has 163rpm at 12V, so should be fast enough as a seatbelt tensioner.

We will see.