2DOF low cost motion platform for Rfactor 2 and GP Bikes

Hello,
I'm Rado, a 3d modeler and maker from Madagascar, i'm also a simracer since 2017. I'm planning to build a very simple and low cost 2DOF compact motion platform. I will use it mainly with Rfactor 2 and gp-bikes but also sometimes with Xplane but very rarely.
I think it will be a "modulable" simple seat mover so i can swap my chair with a bike seat when playing gp-bikes.
I already purchase some item such as the wiper motors / the U joint / 4 ball joints / an Arduino Uno.

I already own a DIY static playseat so i will use the same car seat and the wheel and pedal platform(wich will be static to maximise my wiper motor efficience )
Now i need to purchase 2 IBT 2 motor drivers and the PSU, surely next week.

My first problem is that i have zero welding knowledge so i will surely ask friends to make the frame or pay someone else.

As a Maker i have 3d printer at my disposal so things like the potentiometer holder, the arduino and IBT casing .... etc will be surely 3d printed.

So, here is my first question :

Do i still need to make a "shoulder mount" style compact platform, even if i just need to move my self and the seat ? or the wiper motor (normal car wiper motor, not truck ) can be efficient if i choose the same design as the image below ?





Thanks !

Ok thank for your advise, i will use SimCalc once i'll start the cad drawing but just for validate the concept, i need something like this ? (no precise mesurment yet, just concept) :

Cool ! so i'll start this way. But as i plan also to use it with gp bikes (by swaping the car seat with a bike seat) how could i calculate the optimal center of mass ? cause sitting in car and in bike doesn't surely had the same mass repartition.
My first idea was to calculate the center of mass in "bike position" and the add a rail for car seat so i could always re balance it after.

Awesome project!

I think it will be difficult to find a good compromise between both positions. You'll probably want the roll center much higher when using the bike. Maybe you could have an extension on the universal joint? The motor mounts would probably work fine for both if you have them high like on your last sketch.

Thanks Chris, yes it surely will not be as optimal as if i just build the rig for only gpbikes, the amout of lean doesn't realy matter for me cause as I only play in VR it is just to trick the brain, surely i will need a larger base cause when on bike position when leaning by reflex i'll surelly move my body outside the frame.
Those motor is just to start, if it can handle it, i will surely stay with it but if it doesn't i would surely order dedicated DC motors, my only problem is that i can only purchase from Amazon.fr from my country, so i'm really confused about which to order if i had to, cause things like ZYT90 doesn't exist on amazon.fr

Let's just hope those motor will handle, in a worse case, i always have the option to buy 2 additional wipper motor and double the motor of each axes, but i don't know if synconisation will be hard in that case.

I am a firm believer of small movements for bike rigs as you probably have seen if you followed my thread at the piboso forum, so I absolutely don't think that will be an issue. However, to be able to rotate the mass you want to rotate you really would gain a lot by moving the pivot up. It could probably be made quite modular so it's not too difficult to swap between car and bike. Or do you plan on doing a more sitting down type bike sim?

I'm thinking something like this. It would require you to remove the seat of course, so maybe a little too much of a hassle..

For the seat position, i think it will only a matter of how low the handle bar support will be, to get a "sport" bike position, so it will just be related to the height of the bike seat. But i think you're talking about moving the U joint. It would be possible to make 2 U joint one for each seat and had a "modular attachement" to the base, so to switch from car to bike, i'll have to unscrew the to ball joint and the base of the u joint and put the one with bike seat, it is not a big deal for me cause i'm not switching from bike to car each hour lol.

I'll surely start with the car position with the modular base on my mind and just add the one for bike if needed !

Just got all the remaining electronic parts today, i forget to buy the fan for the electronic case but i think i got one from a computer anywhere here, i just had to find it lol

So for now i had :

2 wiper motors
1 arduino uno original
1 central U Joint
4 ball joints
1 meter threaded rod
2 IBT2
4 10kohm pot (just bought 2 extra in case i broke some )
A 12V 30 Amp power supply
An emergency stop button
Some wire

Just missing the fan if i'm wright.

The IBT's have a tendency to break. A good investment is removing the heatsink and putting come thermal paste on there, usually there is none! With the amps you'll be pushing, I think you will need it.

Start to isolate the motor from ground, i think i made it wright since only one connection (supposed to be the ground) is reacting to the motors body, but what i dont understand is that i think that in a 5 wire wiper motor you have :
1 Ground
1 low speed
1 high speed
2 stop position

if i want to rotate the motor right now, i have to wire the low speed and the high speed to a 12v battery, before i cut the ground, i could wire the ground to the low speed and it rotate slowly, the if i wire the ground and the high speed it rotate with high speed, now i cannot do that anymore. i'm sure i've cutted the ground cause it was the only that was in contact with the motor's body

Thanks for the advice Chris, ok i'll do that, i have thermal paste lying around !

I have only worked with a wiper motor once. Then I just opened it up and connected the driver + side to the cable coming from the rotor that's not connected to gnd. There are strange fwd/back mechanisms in the wiper that you have to bypass..

Not sure if that helps, or did you already solve it?

I’d definitely check if the case is grounded first before opening it, I had a wiper motor off a silverado that was already ground isolated. I didn’t have to open it at all.

Already done that before opening it, check with a multimeter and found continuty for 3 of the 5 connection (i guess it's ground / low speed / high speed) . Then open it and cut the ground connexion, then retest it so now only one have continiuty with the motor body (normally the ground) but now if i connect the ground (the one with the continuity) to the low speed or high speed to a 12V batterie, the motor is not working. I have to connect the low speed and the high speed to the batterie to have the motor working at high speed.

It is working as it is mean to work now (high speed rotation) but i'm confused about which connector is what, i though that the Ground (as it's named) is the one connected to ground and to make the motor work i had to connect the Ground (the only one left connected to ground) to the low speed or high speed connector to make the motor work at desired speed, but no, i have to connect the low speed and the hi speed (the two that is no longer conected to ground) to make the motor spin !
I'll try to make a video

Depending on the construction wipers often need to rotate both ways, so even if you have polarity checked in one position that doesn’t have to be true in the next is what I mean. Try connecting 12V straight on the cable that goes to the motor and gnd on the chassis (looks like one of the motor cables is connected to chassi)

Never mind, according to this tutorial, it is mean to work like that, hihihi, and the reason why we isolate ground for the low and high speed is exactly to not use ground hihihihi, anyway thanks for your advise, i'm no trying to wire it all with the arduino / IBT / PSu etc to test if all is working !

Here i am, trying to wire everything to test if all electronics is working before start welding the frame. Meanwhile, does anyone already made an enclosure for the arduino + 2 IBT 2 enclosure and is kind enough to share the STL ? I could model on but if somebody already done it and is able to share, it will save me a lot of time and to not reinvent the wheel !
Thanks in Advance