3DOF motion seat "fifty-thirty" with heave

Hi guys


this is my first motion rig. I was inspired by this forum. I saw, i read and than i think “i want to build a motion rig like yours”.


My current setup is a playseat challenge with Thurstmaster T248. My first idea was to build a 2DOF motion platform for the Playseat. After a few weeks of research the idea switched to a 2DOF platform with traction loss. And it will be final a 3DOF motion seat.


My budget requirement? Cheap but solid and compact


So, I bought the mechanical muscles first. 3 wheelchair second hand motors. 24V and a lot of torque. The big one comes with 60nm! The two little ones, i dont know.


Then i bought 3 20A power supplies, a joint from a little truck, 3 motor driver BTS7960 and other electric and mechanical stuff. A office chair mechanic (@noorbeast like your smart idea) and a car seat from a BMW E46 ( i’m a german guy ;-) )


I want to use DIY hall sensors.


The 50x30mm steel profiles are sponsored by a bro.


First i visualized my thoughts:





i start to build the rig from top down

i’ve never welded before

I extended the point where the joint is extended for a longer lifting path





These are the first steps.


more coming soon…

My first quetion is about the software i need.
Do i need boot, SMC3 AND Simtools2.6?
What i understand, simtools is the interface between game and moves (Arduino). But without licence useless to test my rig.

Do i need SMC3 ONLY to test my rig and not longer after that?

@noorbeast thank you very much! I understand

let's go forward


at the building time, i change the construction





now the steering wheel rod and floor is installed






more coming soon…

by the way, i installed SMC3 on a Arduino Mega 2560. The original code is for an Arduino Uno R3 and do not work on a Mega 2560. With code adjustment (pin mapping will not work) it works without any problems but the easier way is to buy an Uno R3.

let’s go forward


i have installed belt drive and DIY linear hall sensor 49e





time for color, felt carpet and the muscles







the first wiring (3x 0-24V 480W PSU, Arduino R3, 3x BTS7960) and a successful tests in SMC3

I chose adjustable PSUs because I read that the BTS7960 often cause problems at 24V and I will probably work with 18-19V. Or, if possible, even lower. I found out, that the motor drivers work most safely between round about 8-18V.





My first issue was a low signal from 2 of the 3 hall sensors. Only 3,5V instead of 5V at maximum value. I changed sensors, tried other magnets.But after 45 minutes i found the problem. The sensors receive a weak input voltage. The breadboard has a voltage drop (maybe a sign of aging). Now, it works


more coming soon…

let's go in the "final lap"

the building is done and SMC3 and Simtools allows the seat to move.




now, i will get the electrics in a box

a video will follow in the coming days

Here is my first Video. I tested LFS and wow, it works





Now, i search 3DOF examples for Axis Assignments.

At my first ride, i miss curb-effects. Wich axis is responsible for this?

you refer to my middle axis. there is "heave" movement

i. The fact, I have the exact same motors, and I would like to add heave can you please tell me, what kind spring system are you using? Maybe the specs of it. Thank you very much

Cool project, i wanted such a compact rig also but since i only have wiper motor i did a "shoulder mounted" one, i'm still in welding phase now, big motivation to see other finish their rig !
Keep up the good work

There are no springs, just a mechanism to keep the upper part of the seat from rotating and the lower part
Components included
1 top five cardan shaft
5 bottom 10mm nuts
3 iron plates about 12cm
and components as shown in the picture below

metal bars and round sliders with a diameter of 16mm

I use surge 25% sway 25% and heave 50% on a 2DOF wiper motor rig, and can feel some curbs effect but since my motor is not strong and reactive enough, i get it only on some curbs and not on other.

Maybe you can add some photos, because the video is ab bit dark. I send you PM. Thank you!