Question Motor lever size?

The wheelchair motors I will be using are 24V, 150+ RPM, with an 18:1 gear ratio, but I will be running them at 26V, achieving 165 RPM. Can I use a lever size of around 10 inches (250 mm)? The distance from the motor center shaft to the U-joint center will be approximately 40 inches (1 meter), depending on the center of gravity of the chair, which is still unknown. The width of the top frame is 25 inches (635 mm). Also, I was planning to use 1-inch, 16 gauge steel square tubing with bracing. Would that be good enough for rigidity? I really don't want to use 11 gauge since it might be overkill. See the picture below

It would be nice to use a design clone Reality H3 but I really don't think it's possible with the motors I have. Also, power consumptions is much higher with that design and not really suitable on a breaker 1500W, 120v running everything such as PC, monitor, 3d printer, lights and motion simulator.

There is a problem with SimCalc due to the interface between the chair and the monitor. For some reason, the numbers don't add up in my head, or maybe I don't fully understand what pitch and roll force mean. Regarding the driver, I'll be using a modified IBT 2, probably with BTN8962 drivers with custom radiator, or possibly 100 amp drivers of Ebay. At the moment, it's too early to say. What do you think about lever length? Is it doable with such a long arm to achieve the results I'm looking for?

Do you think with the motors I have would work with a clone Reality H3 designed by Gabriel the simracer member or gearing is way too low?

In my head, the plan was to have the longest distance between the motor and the U joint to work as leverage, and to have a longer lever to move the bed in order to substitute the travel angle. But, as usual, you turned down the idea. To be honest, I'm totally confused about which design to choose. I have no problems with building or electronics, that's the easiest part, but I'm completely stuck on which design to go for. Since I'll be welding most of the pieces, changing the entire design later on won't be fun.

Are there any other 3 DOF designs besides DMax and clone Reality H3 designed by Gabriel the simracer member?

If you have 250W 165RPM motors, that means they are weaker than 250W 75RPM motors, so using such a long lever will be impossible.
I understand that you are building a sim rig for car racing, in which case you don't need too much range of motion, but rather a more responsive signal from the road, gear changes, acceleration, etc.
The H3 design will work, just give it 5-6 cm levers for racing and that will be enough.
You can also download the SIMHUB program, even in the free version, enter the dimensions of your design, and it will show you a preview of the range of motion your design will have.
In general, SIMHUB works very well, is easy to use, and has a built-in soft start.
Download version 9.8.4. I have now noticed that the settings for the 2DOF rotary have disappeared in the latest versions.

As an example, I am posting a photo from my 6DOF.

Watch this thread and see how short the arms of this DOF are.

https://www.xsimulator.net/community/threads/my-finished-2dof-project-videotutorial.16214/

What matters most in a motion rig setup? I look at it pragmatically. No matter the lever arm length, it takes the same amount of power to tilt the rig by a given angle at a given speed—what changes is how that power is mechanically transferred.

My rig uses the same architecture as yours. Each motor movesthe rig about 13°, as measured on the rig. My lever arms are 80mm at the motor, mounted 550mm from the center, giving roughly a 7:1 ratio. That works well for me. To get the same mechanical effect using 200mm lever arms, you'd need them placed 1400mm from the universal joint. That 7:1 ratio should always give you 13°. (Theoretically that's the arc tangent).

EDIT: This assumes that an 80mm lever arm gives you 125mm of travel.

Is 13° enough? Yes. Side-to-side motion (one motor up, one down) gives you 26° of roll, which is more than I ever want. Pitch movement (both motors up or down) gives you 13°. In my experience, that’s enough—when I hit a wall in F1 at that angle, it hurts. On some RBR stages, it gets wild and throws me around hard.

One big benefit of the u-joint setup is how it carries the rig’s weight. For most people, the center of mass is near the front of the seat, so positioning the u-joint at the center is key. I made some effort during the build to find the rig's balance point. Mine is front-heavy thanks to a DD1 and the heavy 80x120 extrusions supporting the wheel.

I mounted the lever arms under the wheelbase support—it was convenient and solid. My rig is extremely stiff except for the pedal mounts. It’s strong enough to support the pedals, but not the best place to push with motors.


I need to add an RBR video.

https://www.xsimulator.net/community/threads/wood-andmetal-2dfo-rig-version-2-0.18854/