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archcvd
07-10-2008, 09:03 PM
These are GORGEOUS: http://www.trossenrobotics.com/store/p/5761-Motor-Mount-Wheel-Kit-with-Position-Controller.aspx?a=blog

Very nice guys!

I totally want a pair.. :eek:

darkback2
07-10-2008, 09:24 PM
Those are the same motors I use on Vivian. My students used them also. They are GREAT!!! I've had students ride on robots used making these motors.

It only sucks that we had to send out to have the aluminum mounts we used cut on a CNC machine, and I had to mount the wheels myself using wooden dowels and a drill press. Seriously if you don't have a set of these buy them!!! you won't be disappointed.

DB

metaform3d
07-10-2008, 09:47 PM
Ooo, I like those. How much weight can they bear? I didn't see that in the specs.

Adrenalynn
07-10-2008, 10:21 PM
If there are specs on 'em, we can figure it out easily enough...

And that's what I'd like to see - what are the torque numbers on 'em?

Parallax is in Rocklin? [boggle] Just up the street and I never knew it?!?! Wonder if they're hiring? :)

[edit] That gearmotor is used for power windows and power seats in cars. Darned if I can find torque-specs on it though... The motors sell used-surplus for ~$40ea. With all those machined parts and encoders, that's a pretty good price for the kit.

darkback2
07-10-2008, 11:25 PM
While I don't have any specs on the denso motors, they were originally power seat motors for cars. They have a plastic gear inside, and work via worm drive. I run them at 12 volts, and using 5 amp hour batteries I get about 20 minutes using 4 motors. I know I'm not being very specific...I don't have a specific weight on vivian, but with 6 inch wheels she does a good walking pace. She feels like about 20LBs...maybe a bit more.

Adren, PM me your address and I'll see if I can't send you two of them...you can get all the specs you want that way.

DB

Adrenalynn
07-10-2008, 11:27 PM
If you're sure you want to do that, I can stall them at a few different voltages and measure torque, as well as real RPM under load, and send 'em back. I'll PM shortly.

darkback2
07-11-2008, 12:56 AM
I spent some time under the house and dug out a right and left hand version. I wasn't able to find any of the aluminum mounts that I had made for them...

In anycase...They are all boxed up and waiting to go.

DB

ScuD
07-11-2008, 05:41 AM
Now THIS is a community.
It amazes me how "close and personal" this board is..

Beautiful system indeed, those machined parts look amazing.
Price is indeed very affordable given the parts included!

Adrenalynn
07-14-2008, 05:08 PM
Thanks to Darkback2 for his incredible generosity (and fast shipping! :) ) - I now have a left-and-right matched set, and know a lot more about these motors.

I don't know the history of the set I have here, so I'll need to chat with DB a bit before putting my foot in my mouth, but they appear to have very little operating hours on them.

They are carbon brushed motors. Just under 1.5lb average over my sample of two.
11/32" [9mm] shaft
1-1/4" shaft length
1-3/4" motor diameter
Overall Length: ~7-3/4"

They are very torquey. I ran them from 3v to 12v DC to generate various nominal graphs. My curve fit over n=2 was 99.7742%

I'm ready to post the 12v graph, and I'll follow-up with others as time allows. I wanted to get this one up quick with the Thank You! to DB2!

So in summary, we should observe something approaching 420 oz-in pretty easily, peaking much higher, and 153 RPM unloaded in my samples with just under 100RPM being the sweet spot where HP/Torque curves intersect.

archcvd
07-14-2008, 05:12 PM
Good stuff Adrenalynn! Thanks for the info.

Adrenalynn
07-14-2008, 05:17 PM
No problem! I'll get more complete graphs up shortly, but that should get people started thinking. That's a lot of torque-to-weight.

darkback2
07-15-2008, 02:11 AM
Thanks for creating the sweet graph. I'll incorporate it in my class. It will be good for my students to have the actual data when they burn through our batteries in about 15 minutes using 4 of those motors.

Adrenalynn
07-15-2008, 02:24 AM
My pleasure! More to come!

What kind of batteries do you use? I can also account for terminal resistance and efficiency from the power source. When you run all the numbers, it still surprises me how close my models get to reality...

darkback2
07-15-2008, 03:01 AM
12 VOLT 5 AH GEL CEL BATTERY
http://www.allelectronics.com/mas_assets/image_cache/image_product.height.500;width.500;modified.120785 6470.GC-125.jpg

darkback2
07-15-2008, 03:02 AM
they are pretty cheap though. both me and the school are on a pretty tight budget.

DB

Adrenalynn
07-15-2008, 11:07 AM
Standard fare, though. Alarm systems, garage door openers, starter backups, ... Those little gel cells own the world. They deliver a tremendous amount of quick amperage, and are really stable. They're also heavy by today's battery standards.

I still use more than a dozen gel cells in personal projects today. Good clean fun for not a lot of money. :)

We'll toss a gel cell into the equation. :)

droidcommander
08-07-2008, 03:13 PM
Anybody have further numbers on what a bot using these motors could handle payload-wise? I'm thinking of building a rover/cleaning bot for my home and want it to be able to pick-up and carry multiple items left on the floor before disposing of them at a common location.

Thanks

Adrenalynn
08-07-2008, 03:31 PM
That's a sorta complicated question, so let's just make some assumptions:

You wanted to be able to drive up a 10% incline. Your wheels are 6". You can live with a 0.5mph top speed. Then these motors will easily handle a 75lb total weight robot.

Let's say that you want 1mph out of it, then you're going to be looking at a 50lb 'bot.

This really depends a lot on *all* the parameters of your application.

revoltage
09-13-2008, 10:58 AM
Thanks for these graphs Adrenalynn

4mem8
09-13-2008, 03:44 PM
Adrenalynn, you are so generous, thanks a million for the info, I was one of the first 5 to order a set of these Parallax motor drives at a reasonable price and may use them in my next project, so having this info is of great help to me as Parallax have not got this info on their site. Thanks again. + 1 rep for you