Beginning a 2 DOF Seat Mover Build

Hey All,

After gathering resources, hardware suggestions, and design ideas I'm beginning to order for my build. Here's my main components list:

• 2x Crab Pot Motors:
  • http://www.ebay.com/itm/GEAR-MOTOR-...PULL-FEED-150-160-rpm-25-1-ratio/351066992384
• PSU DPS-600PB:
  • http://www.ebay.com/itm/361318608455
• 2x JRK Motor Controllers:
  • https://www.pololu.com/product/1393
• 2x Hall Effect Pot:
  • http://www.digikey.com/product-detail/en/0/987-1393-ND
• Seat: Junkyard pull of a Toyota Yaris Seat.

I haven't begun with the exact metalwork for the frame, but I'll be heavily borrowing from existing 2dof compact seatmover designs with pedals and wheel/sticks on the moving platform, versus stationary.

So for now, I'm interested in feedback on part selection, if anything is a glaringly poor choice. For example I read that 360 degree pot may not have been the best choice? Will resolution suffer enough where I should get something more like 180 degree pots to take advantage of their full range?

Secondly, what is a good target weight for the seat? My junkyard seat weighs in at 30.4 pounds (13.7kg)

Thanks!

Completed video:

360 deg pots , single turn are good, they might only use not even half that turn to read, but if the motor goes mad, and spins over and over, you dont have a broken pot.
Ive used 270 deg, 180 deg and 360 deg pots on JRKS. I only use 360 deg pots, single turn, continuous turn because they cannot be broken from accidental overshoot.
Seat weight is ok, just balance the whole set up right.

Good to know. Seeing as how I'm a total beginner not breaking my pots sounds like a good thing.

Yeah, some times it pays to spend a little more to get less headaches. Like you, I use JRKS, granted they cost more, but they are simpler to set up overall.
Although some Arduino users will disagree.

I've used programmable boards like adruino before and 1 out of 2 had some bad blocks of memory, making large sketches not function.
I'll pay a bit more for no programming and simplicity.

For the project I won't have updates for a small while. I plan on waiting for the important parts to get a better overall feel of sizes/mounts/etc.

Update! I've finished the majority of the seat frame. I'm going for shoulder mounted with onboard pedals/wheel/joystick. The frames on car seats aren't actually symmetrical, which caused a bit of trickiness when making the shoulder bar. If I could do it again, I wouldn't use a car seat. Lots of adjustability for the pedals and joystick height as well.

Carseats cheap, but can be heavy.

Yes I agree. I think the motors should be able to handle it with the shoulder mount. Do you think I'm cutting it close on weight?

could be, see how it goes, balance it right THE FIRST TIME

Hey @WhiteGoblin - first off, good luck with your build!
The lighter you can make it, the better. I agree with @bsft, make sure you spend enough time on balancing the whole thing. And when you do, make sure you have everything that will be part of the final rig on there, including yourself.
One other thing to consider is that the 25:1 gearboxes won't hold the entire thing in position when they are not powered.
Other than that, it's looking good already.

Thanks for the feedback. Yes I've got the balance point marked and I'll check it a few more times before I commit to welding, just to make sure it is correct. I'm tempted to change out the seat for something lighter, but I'll see how it goes. As far as the motor gearing is concerned, 25:1 compared to something like 50:1 means a faster motor, but less overall torque, correct? So I should go with a shorter arm to make up for the lower torque value? Also, what angle should the motors be mounted. I've mostly seen the arm extending backwards, but what would change if I mounted the motors so the arm is parallel to the shoulder bar, or even at a 45 degree angle?

Without getting technical and measuring Exact #'s for degrees, This is Close to ideal for your angles....straying too far away from these angle's will only lead to more load on the motor's and slower performance.

Awesome, thanks. I've decided I'm just going to do it right and ordered a lightweight racing seat.
It'll shave off 20 pounds of the final weight, a lot of that being topheavy weight on the chair back.
I'm also going to take the opportunity and make the frame symmetrical.
Now I just wait for Santa... I mean USPS.

Quick update. I've gotten the new chair and redesigned the entire frame. It's much more compact and focused. Next up is competing the bottom frame.

I'm currently harness shopping, and noticed that some people use springs on the harness to simulate tension during braking. Can anyone let me know if that effect is worth the cost? Any adverse effects on the motors? Also, would trampoline springs work? They seem to be the cheapest option:

amazon.com/Upper-Bounce-Trampoline-Heavy-Duty-Galvanized/dp/B005OCYUMI

Congratulation cool design

I have not tried it without springs so I can't say what is would like that way. But I do like it with the springs, it works well. This is what I bought http://www.ebay.com.au/itm/SPRING-K...49?pt=LH_DefaultDomain_15&hash=item3aa916be91. I then set it up with 6 of the strongest springs of that kit. They are all mounted next to each other to give the whole setup more strength. I first thought all of those springs might be to small and I wasn't sure if it would work or if I even like it. But for the cost of this kit I thought I'd give it a try.
As for affecting the motion, I personally can't tell the difference between wearing the harness or not. If anything, wearing the harness adds to the immersion especially under brakes as you feel the pressure of the harness on your shoulders.
I think it works well.

Thanks for the advice. I've gotten the seat mounted to the frame and everything is looking good. I made one small mistake in that I could've mounted the ujoint a half inch closer to the seat but accidentally left some unneeded material in. My question is: is a small improvement like that worth grinding and rewelding? It would be pretty time consuming. Does .5 inches matter for the ujoint?