Question Small motors and gearbox selection for Thanos AASD

Hello all, it's been a minute!

I have my Thanos AASD electronics already that I bought around 2019 before my life changed much and I had to put my sim projects on hold.

Right now I'm planning my own homebrew G/Motion seat as the first step to getting motion back.
I need motors and actuator assemblies appropriate for a reasonably beefy G-seat type project.

Do I pretty much just need to go with the smallest AASD motors and drivers or is there something perhaps smaller and/or less expensive that would be compatible and a better choice?

I'm also looking for some kind of home brew equivalent to the SRF threaded ball screw gearbox from DOFReality I can hopefully build to use with those motors to try to keep things compact.

Cost is a major factor so keep that in mind!

Thanks for any help!

Or, alternatively should I be going with a totally different solution for this application like large RC servos?

I know nothing about this kind of stuff, and so far have stayed away from anything that won't run on 110 or 220v house current directly.

I do have my set of six AASD M04025 4N.m 1.0KW on hand I could use despite them being massive overkill and not as compact as I'd like, but still have been planning to use those for a motion platform later. I might consider using these for the G-seat as I would definitely benefit from later buying bigger AASD's that have significantly more torque for the motion platform I plan to build.

Certainly if there aren't any alternatives that would be a lot cheaper than buying another set like these or bigger I'll just want to use what I have.

If I decide to go that route, I just need guidance on creating my own SRF Threaded Ballscrew gearbox equivalent to fit the MO4025's.

Welcome back!

The motors I use are long and slender so they are nice for packaging against a seat. If you want to focus on cost the motors you have will certainly get the job done.

I would stay far away from rc servos. They are like a moped to a race car compared to proper ac brushless servos.

Excellent, thanks guys! I'll sit down and read that thread right after lunch.

@cfischer Your thread was great help for getting some ideas and seeing how you built your seat. I'm building for flight vs. you for racing but I will still likely use some of your ideas. Particularly your u-joint usage, and maybe some of your servo layout.

I'm very interested in the results of your bottom bucket surge testing. I'm going back now to look closer at that but you didn't show it later on so not sure what the final design was. You mention not liking a "shear" effect there, and trying to see if what I was planning was contrary to that as I'm not sure I understand. The bucket surge pushing my lower back against the back of the seat is one of the things I'm expecting to be particularly effective in my very different seat design.

@noorbeast Are you aware of any threads or anything that may help specifically for trying to build a DIY version of the DOFReality SRF Threaded Ballscrew gearbox equivalent? I'm sure I could learn from seeing how others have constructed their own versions!

Without going back and reading my words I think I was saying is moving the seat bucket side to side was no good and moving front to back is a huge win. Be sure to pay attention to the angle of the motion relative to the seat. My seat is pitched back 25° or so. The seat motion is level. This shoves my body back into the rear of the chair. The result is more noticeable pressure on my low back than my legs.

If I moved the seat back at the same angle of my legs then I would primarily feel a shearing on my skin and that sucks.

The videos show the latest seat bucket motion. I would do the same for flight any day.


The most important sensation for flight (in my ignorant opinion) is low frequency heave. How do you plan on providing that sensation in your sim?

I built a pair of ballscrew gearboxes for my P3. They work very well, although I really should have gone with a 3:1 planetary coupled to the original motors instead of the fidget motors. I don't do any driving games and tool around in a Cessna 172 or Bell 206 most of the time so the speed is good enough. I'm currently building a Bergison motion G-seat, and will be selling the P3 and gearboxes when the G-seat is finished.
Here is the second version of the gearbox in motion.
And the first version. https://www.xsimulator.net/community/threads/sort-of-diy.19294/

@Thick8 Awesome! Can you share any info on how you built them, especially any drawings or 3D models?

Edit: I have pretty much decided to use Bowden Cables (bicycle brake/shifter type cables) actuated by basic ballscrew/servo motor assemblies for the G-seat motion assemblies that have no real load on them.

That's mostly the seat back heave and sway parts of the seat.

My design calls for six functions, using six servos:

Seat Back: Heave (vertical slide), Sway (horizontal slide), Surge (forward back tilt hinged at bottom).

Seat Bottom: Heave (hinged front edge, actuator lifting from rear), Roll, Surge (forward/aft slide of entire bottom assembly parallel to the floor of the cockpit).

The back surge, bottom heave, and bottom surge will probably be standard ballscrew DIY linear actuators and slides.

That leaves the bottom tilt, for which I might try to do something like the threaded ballscrew gearbox type of thing

That's exactly what I had in mind after giving exactly that question some thought, and I looked at your videos to confirm you did it the same way I planned to. The bucket surge motion is going to be the final assembly at the bottom, parallel to the floor of the aircraft.

That's no ignorant opinion, that is scientific FACT!

Eventually I'll have the whole thing on a platform with big heave travel (somewhere around one meter of heave) for exactly that reason. In fact, it will basically be just a heave platform and almost nothing else. The only other thing I have decided to add is a surge tray mostly for carrier launches and arrested landings, but will also help a lot with firewalling the throttle in combat aircraft and braking after landing on terra-firma.

As far as how I plan to do heave with the G-seat itself, well one part is the seat back will move up and down for a less effective but equivalent effect to the surge motion you use, scrunching my butt down into the rear of the bucket a little. I have another super secret innovation for heave on the G-seat I'm going to be trying that I won't reveal yet, and it may not work at all. Oh, and another semi-secret addition that would mostly just take too much typing to describe right now, that will help with heave some but especially surge. Well, that's if it works!

When I started planning this project years ago this was the thread https://www.xsimulator.net/community/threads/trips-g-seat-project-primarily-for-flight.13975/ This all started when I learned/decided that a stewart platform really is kinda trash for high performance flight (and racing) after having built my first one seen in my avatar image. Anyway, I've continued to think on it in the years since those posts and have a couple very different ideas now.

In the process of all that I found the ACME DMS seats which were extremely similar to a lot of the design elements I'd come up with, so I'm actually trying to replicate them to a degree. I'll attach an image of their design. That said, I disagree with a few things they do, and have a few crazy ideas of my own.


The biggest thing I got from them that I hadn't come up with on my own is how they tilt the seat bottom for the sway/roll effect and I'm definitely planning to try that.

Much of what my plan currently calls for is almost exactly opposite what your rig and most others do. Unlike racing there isn't so much in the way of side bolsters you'd be getting pressed against. When I roll left wing down, the seat back will actually just slide to the right to move my upper body in that direction. Hugely different from a racing design! Also the seat bottom will roll/tilt to the right at the same time, so the system is basically trying to dump me out the right side of the seat, and I come up against what little side bolster type support there is which is stationary, but perhaps mostly feel the movement against the harness keeping me in the seat. Also my shoulders will be contacting the sides of the metal lower canopy frame when I get pushed outboard, which should be excellent for motion cues!

If nothing else it will be good science, I can always modify it heavily afterward.

That's exactly what I wanted Noorbeast, thanks!

Here's my Fusion360 drawing. It includes the CNC tool paths as well. Hope you find it useful.

This reminds me of my attempt.


The effect was pretty uncomfortable. I was surprised and disappointed. But maybe there are tweeks to make it better. Not sure, but I abandoned it.

The ACME seat is interesting. They have a youtube video for others reading along.

I hope you share what you find. Will be interesting to see.



I always wished I could have driven seattimes gseat. It sounds like some of your ideas are implemented there.
He took down all his excellent content a long time ago but luckily I downloaded some of it.