Question for people using wiper motors or scooter motors

So I am just starting a joyrider build, but thinking a bit in the future, how do the electronics know the positioning of the motors? If they are wiper motors or scooter motors I would think the electronics need some kind of encoders to properly position the motors. Am I missing something, or is there something I dont understand....

Reason I ask is I saw this inexpensive solution to knowing the position of the motor.. http://letsmakerobots.com/blog/aniss1001/homemade-wheel-encoder

Hi @wthierry, Most people use a resistive POT (potentiometer) for the position feedback somehow mechanically connected to the the motor shaft. There are lots of different ways of doing this, but again the most common and probably the easiest is to connect the POT shaft direct to the motor shaft with a suitable coupling. Others use gears or belts or other ingenius ideas. If you search some of the existing designs you are sure to find examples. It's a pretty common design topic.

As for pot mounting, drill a hole in the back of the motor bolt, and slip the pot shaft in, then instead of drilling right through like I did (pain in the butt) tap a 3mm hole in the top part of the hex on the bolt and screw in a 3mm grub screw or bolt to hold the shaft steady.

As for wipers on a joyrider,

ignore the information about how I mounted a pot, this is old and back of the motor shaft works better

Sounds good, Looking at motors to drive it, I was looking at something like this: http://www.ebay.com/itm/like/351158629824?ul_noapp=true&chn=ps&lpid=82

They are 180 watt 12v motors similar to this: I am wondering if they will be strong enough to move a rider that weighs about 250 pounds. Or should I shoot for something more hefty....

Yes they would

The 2nd rig i built for a buddy uses those motor's. No issues really, But buddy hasn't played with it much since i built it (less than an hours worth)

My main concern is reusability. I want to build a joyrider because its a relatively simple rig and inexpensive. But I want to move up to a 3dof or even a stewart type design in the future, and wonder if these are good enough to take along to another project. Or would I be better off selling the Joyrider with motors and starting fresh?

choice is yours, although I re-used the wipers off my old joyrider onto the next 2 2 DOF sims.
If you are worried about the motors, use 50:1 or 60:1 boxes on them for greater torque.
For 3 DOF (2 DOF balanced and drift) , these are fine,
For 3 DOF lift, look at larger powerful motors, like 24 or 240v motors.
For 6 DOF, several ways, 12v motors on custom actuators @SeatTime I recall was up to something, or 240v motors.
Just for reference, my joyrider would have cost me more than the next build if I had to buy the steel. I used a LOT more steel in my joyrider than my 2 DOF balance sim.

Im doing the PVC joyrider, at least for the outer frame, maybe the seat contraption will be steel havent got there yet. But will order a couple of those motors and finish my frame and attach caster bearings in the meantime

One more question, I have searched the forums, but not finding much info on how to mount say a bike chain gear to an arbitrary motor shaft. Also, where to find these kinds of items that are fit to mount to motor shafts.... thanks in advance.

You can do something like this with standard bike parts (from my old sim)

or purchase a motor with the cog already fitted - similar to what is shown in this link: https://www.motiondynamics.com.au/united-my6812-12v-dc-100w-2750-rpm-electric-motor-chain-en.html

so many decisions to make... Frame will hopefully be done this weekend, so going to order some motors tonight... Thanks for all the tips guys! Will post some pics over the weekend of how the build is going.

I use wheelchair motors

Powerful quiet and have a built in gearbox