DIY 3DOF two-seater

Fantastic! I appreciate this view of it! I am designing a frame very similar to yours. Are you using a U-joint for a pivot? May I ask what the length of your ball screws are and about how much travel you get/need? I was thinking about actuators that are much shorter than what it looks like you have but I have not yet figured out the travels.

Thank you very much,

Scott

Here is a better picture of the connections of the actuators to the rig. Although there are bearings with crossing axes it's not really an U-joint.

There has to be a kind of a "pendulum arm" to compensate the horizontal distance of the pivot points when one actuator moves upward and the other downward.
Although it works quite well I wouldn't take this build as model. We built it before joining this forum. With todays knowledge I'd probably design it more like @peter stolmeier 's platform.
We found out that +/- 150mm stroke is enough. But make sure to have 10..20mm pitch and not the most common 5mm.

That's great info. I will look at Peter's build as well. I am thinking of using a u joint near the CG as the pivot and then u joints at the actuator connection to the sim base. That would give me 2 DOF. Thanks for your information very helpful.

Scott

I assume this has to do with the speed of the actuator?

Yes. For a small "seat shaker" like shown in the ads that are inserted into almost every post 100mm stroke and 200mm/s speed is enough because the actuators are close to the center point, e.g. directly in the corners of the seat.

But if you have a larger rig where there is 1 or 2m between the actuators you need more stroke and speed. Also, if the ball screws rotate at lower RPM they are less noisy. Of course, for a higher pitch you need more torque to generate the same forse.

As a rule of thump, 5mm pitch and 1Nm torque at the motor shaft generates around 1kN linear force.

Thanks I think I need to dive in and start building some prototypes and see how it all works together. Thanks for sharing so far.

Scott