2DOF DIY Seat Mover with aluminum frame

Hello!

I've been lurking long enough, and all of my supplies finally arrived, so it's time to start my build!

After looking through many threads, I decided to follow a (seemingly pretty common) pattern of using 24V wheelchair motors, cheap h-bridges, an arduino, and hall angle sensors.

I started by ordering a lot of things from AliExpress, but I did find a few things on Amazon so I mixed it up. For instance, the power supplies seemed to be the same price from either (after shipping) so I ordered them from Amazon so I could return more easily if needed. (so far not needed)

On the advice on @congb17, I ordered aluminum extrusions from TNutz.com, and I have to say that was good advice. Great prices, package was well protected, and everything was cut exactly as requested. I was going to go with wood originally, but after assembling the aluminum, taking some apart and re-assembling, I am happy with what I have. I used May Cad to figure out what I needed.

Now on with the fun!

I'll start by posting what I got from AliExpress. This was a bit difficult, because the listings are not always easy to understand, and I was worried about getting the correct size or specification of what I wanted. I learned quickly about checking for more options below the main listing, because sometimes (like the motor rpm) important things are down there and do not default to what I wanted.

Here are the things from Amazon.

I got adjustable voltage power supplies so as to not burn out the motor drivers.

I also already had some wire, ferrule crimping kit, Dupont connectors, solder, etc, but if anyone wants more details, ask and I will post them.

I mentioned tnutz.com in my first post, and I thought they deserved their own call out for the quality of their work.

This is the unwrapped package. I don't have a picture of the package as it arrived (I was so excited to open it I forgot), but there were multiple layers of cardboard on all corners and along all edges, as well as the wrap seen under the aluminum in the picture below.

There were multiple weights of extrusions available, with different prices. I ordered the light extrusion (because it was a couple hundred dollars cheaper), but after I ordered, I was worried that it would not be string enough. After opening, handling, and assembling the base, I think they will be just fine.

Here is a picture of the inside:



And here is everything laid out:



I also ordered some extra t-nuts (seen in the lower right of the last picture) to use for mounting the motors, arms, u-joint, etc. Compared to using an 8mm flange bolt I think the t-nut has more grab. I did not try a larger flange bolt, but I will think the t-nut would still be better. The t-nut has a good 20mm of bite along the extrusion. (not visible in the picture below, but somewhat visible above)

See the comparison below:

As far as hardware, I tried Lowes and Home Depot, but their inventory was woefully low. I did find a few things and bought multiple sizes of whatever they had, planning on returning what I did not need, but it would not be enough to complete the project. I started to search on Amazon...

Then I remembered Ace Hardware... This nearly forgotten gem has more metric hardware than Lowes and Home Depot combined, and they sell everything individually, instead of in packs (like the big box stores).

Ace is the place, and they had everything I needed, all nicely organized. (While I was there an employee was going through the bins and putting things in the correct places. I don't know if all Ace's have this same level metric inventory or service, but I was thankful that mine did!)

Ace is more expensive than the big box stores, but for me it was worth it.

I have to thank @scruck for the design of the motor arms and stl files for the Arduino and motor drivers.

I found a local company with a water-jet that would cut the aluminum motor arms for just the setup fee of $50. I had to do a little bit of filing because the water-jet left some curves where the nub fit into the motor shaft, but after that things fit nicely. The main arm is 1/2 in thick, and the smaller retainers are 1/4 inch.

I know I should have done a bench test first...

But as you can see, I started to assemble the frame and just kept going. (This has been over the course of the past week, spending evenings putting things together)

Once everything was together and I fired up SimUtils, and no motion.

I was regretting not testing first.

I had labelled all the wiring so I started checking everything against one of the diagrams on the site. Everything looked good, so I started to unplug wires and test them with a continuity tester. Ended up the jumper on both of the motor drivers was only working on one side. I had used some old wire which had not taken the solder well. I remember doing it and noticing the wires were old, but I tried pulling them apart and they did not budge. Lesson learned.

Always verify connections with a continuity tester!

Once I fixed those wires, I had motion. See the pictures below for the results:

Left side (motor 2):



Right side (motor 1):



And here are the screen grabs from SimUtils. Please let me know if anything looks out of the ordinary. I know some tweaking probably still needs to be done.

Now that I had verified the motion, it was time to mount the electronics.

I am going to state up front that I suck at wire management. But don't those 3d printed cases look nice! (thanks again, @scruck )

Oh, and I forgot to mention, I am using MFD and long 8mm bolts with tnuts to hold the bottom flange of the u-joint in place. There are a couple extrusions under the white. The top has a thin piece of hardboard with a circle cut out to help the flange have better contact with the two aluminum extrusions on top.

It was time to set up SimTools in demo mode and get LFS running. I was scratching my head a lot until I found this:

https://www.xsimulator.net/simtools-quickstart/

It's a bit old but seems to still be good.

I also found this post:

https://www.xsimulator.net/community/threads/2-dof-flight-race-build.16924/#post-226548

Which had a basic setup for axis assignments in SimTools. I set mine up the same and when I ran output testing everything seemed to work (and move) as described.

I downloaded LFS, installed, and ran it one time as instructed in the quick start. I had to fiddle with the control assignments, but other than that I could move and steer the car around the course in a training run.

Next I patched the game and when I ran it again I could see the base moving along with the car motions. Wow. That was so cool to see.

Just a pause here to say what a great community this is. I would never be as far as I am in such short a time if it weren't for all those who have gone before and figured this out and shared their experiences.

Thank you everyone!

I had to get the seat mounted and try this thing out for real!

I bought a used office chair from Facebook Marketplace a few weeks ago in anticipation of using it with the moving base. I was trying to think of ways to mount it, and decided to use some old aluminum computer rack rails. Looking at it in the pictures I think it is not an optimum seat angle, but the balance is good when I am sitting in it. I think the back of the seat needs to be lower. I can adjust the seat front to back in case the recline changes the center of gravity.

I still have some cable management to take care of, extrusion end caps to put on, and I am sure after using it for a bit I will need to tighten things up, but all in all I think I will enjoy this a lot!

Now to get a license key!

hello, very nice seat to play. more comfortable than a bacquet. Not too much weight for the engines?

The seat is not too much weight. I think the motors could handle more if needed. I removed all the hardware (lift, tilt, wheels, etc) and it works very well. I considered adding the tilt back but that would require some metalwork. I am more in need of a front/back motion for seating distance.