Author Topic: motors / motorcontrolers for a 2 powered wheel, 2 lb robot (Read 2717 times)

dellagd · « **on:** April 12, 2009, 02:07:53 PM »

I know what you all are saying:
"look at this!"
http://www.societyofrobots.com/robotforum/index.php?topic=7634.0
I saw it but I thought he might have a different situation than me and I don't want to take over his topic, so...
I want to convert my servo driven robot to a motor driven one (don't ask why)
could I just hook this up straight to my board? it takes 5v?
http://www.quality-deal.com/osCommerce/product_info.php?products_id=84
or if I can't use that, then what H-bridge / motor controller should I use and what motors?
any help will be appreciated.

SmAsH · « **Reply #1 on:** April 12, 2009, 03:34:31 PM »

in short no. you need a motor driver. the reason for this is that the motor will draw too much current and fry the pin, i think most can only supply like 30-50MA. is your motor 5V too?

dellagd · « **Reply #2 on:** April 12, 2009, 06:05:01 PM »

well I really don't know what kind of motor I would need.

SmAsH · « **Reply #3 on:** April 12, 2009, 06:22:02 PM »

well first figure out which motor you need then we can talk.

Razor Concepts · « **Reply #4 on:** April 12, 2009, 06:27:56 PM »

You will need a geared motor, something like this
http://quality-deal.com/osCommerce/product_info.php?cPath=24&products_id=134

dellagd · « **Reply #5 on:** April 12, 2009, 08:21:15 PM »

Quote from: Razor Concepts on April 12, 2009, 06:27:56 PM

You will need a geared motor, something like this
http://quality-deal.com/osCommerce/product_info.php?cPath=24&products_id=134

that is in my price range, but I'm not sure how to make sure it has enough torque.
also, http://www.societyofrobots.com/RMF_calculator.shtml I'm not too sure how to use this.
so is 0.4kgf.cm greater than 49 oz-in (which is the servo I am currently using )?

dellagd · « **Reply #6 on:** April 13, 2009, 05:30:42 AM »

ok.
how would this motors work?
http://scientificsonline.com/product.asp?pn=3041860&bhcd2=1239621754
or some of the gear boxed motors on this page?
http://scientificsonline.com/category.asp?start=16&c=421187

SmAsH · « **Reply #7 on:** April 13, 2009, 06:16:50 AM »

Quote from: dellagd on April 13, 2009, 05:30:42 AM

ok.
how would this motors work?
http://scientificsonline.com/product.asp?pn=3041860&bhcd2=1239621754
what do you mean by how?

Canabots · « **Reply #8 on:** April 13, 2009, 08:48:29 AM »

I think what he means by "how" is how well it would work for his robot platform.

Well, looking at the first link, the gear motor(s) (scroll down to view pricing) is apparently really strong, but it is also very slow (the majority being only 30RPM or less). The speed of your robot may be and important factor to your purchase. Also, the cost appears to be about $25 each. Is that within your budget? (What exactly is your budget?

)

Have you looked at the Solarbotics Gearmotors (http://www.solarbotics.com/motors_accessories/gear_motors/)? I find their quality is good for the price.

For torque conversions (if you need to convert different torque units) I typically use this: http://www.linengineering.com/flash/Calculator.swf though there are many more on the internet that are MUCH more precise (they go to 10 decimal places or something

)

Good Luck

dellagd · « **Reply #9 on:** April 13, 2009, 03:13:55 PM »

my price range is "cheapest possible that will work"
I'm going to look on ebay now.

EDIT:
how is this?
http://cgi.ebay.com/One-Mini-12V-DC-High-Torque-Gear-Motor-300rpm-for-Hobby_W0QQitemZ270368883354QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item270368883354&_trksid=p3286.m20.l1116
looks pretty high torque

also then what motor controller / H-Bridge would I need?

robomow · « **Reply #10 on:** April 13, 2009, 11:57:02 PM »

I would define how fast, total weight of vehicle, maximum slope to travel, etc. to define the specs for your vehicle then work backswards to get torque, then watts then divid by volts to get current draw of motor in amps.

Does your robot need to go forward and back. do you need one or two driver motors. Ie. differential steering with two drive motors easy to program? Or one drive motor and one steer wheel using servo?

That 8watt 12V motor will pull .667 amps with no load but will probably pull 2 or 3 Amps at least with resitance. So You need a controller that will handle that current without burning up. Also, some of the smaller current controllers need 13 or 14V supplies to get 12V to the motor.

Also, if you want to pull more amps/more power for less dollars. Then head to radio shack and buy some 3055s MOSFETs and get some big pieces of aluminum to attach to them with four of these you can build your own controller cheap. If it need to be bidrirectional then gets some tip120 darlingtons to switch the direction of the motor current(needs extra pins from controller.) Make sure to test the software so you don't short the control outputs.

here is a simple bidirectional controller for smaller motors http://www.me.umn.edu/courses/me2011/robot/technotes/bidirectional/bidirMotor.html

dellagd · « **Reply #11 on:** April 14, 2009, 06:04:28 AM »

ok so I have decided that I will use the motors I found on ebay.
so I need a motor controller that can havdle at least 3 amps and 12v.
I did find this:
http://www.dimensionengineering.com/SyRen10.htm
but that kind of blows my budet. I don't know if this is unreasonable, but can anyone show me a tutorial on how to make a motor controller / h-bridge for ~$20?

Canabots · « **Reply #12 on:** April 14, 2009, 07:11:33 AM »

Perhaps Try this: http://www.solarbotics.com/products/k_cmd/

It can handle up to 4 amps, and up to 50V, so there shouldn't be an issue in terms of power.

It's also within your budget so there's another plus...

dellagd · « **Reply #13 on:** April 14, 2009, 06:04:31 PM »

how hard would that be to solder, Canabots?

SmAsH · « **Reply #14 on:** April 14, 2009, 06:16:25 PM »

looks relativly easy, the hardest part i can see the the 298 chip itself. everything else looks good.

dellagd · « **Reply #15 on:** April 14, 2009, 06:44:21 PM »

ok I think I will attempt it.

SmAsH · « **Reply #16 on:** April 14, 2009, 06:52:22 PM »

good, i might have a go at making one of my own from their schematics. as that is hell expensive for me

Canabots · « **Reply #17 on:** April 14, 2009, 07:02:10 PM »

Quote from: dellagd on April 14, 2009, 06:04:31 PM

how hard would that be to solder, Canabots?

It isn't that hard. I think it took me around 30 to 45 minutes max to solder the thing together. It's all Through-Hole components too.
I'd say don't heat the IC anymore than you have to (so you don't damage it) and to remember to solder inside, then make your way out (I forgot that while starting the L298

) since it's easier and you won't run out of space.

SmAsH · « **Reply #18 on:** April 14, 2009, 07:13:11 PM »

Quote from: Canabots on April 14, 2009, 07:02:10 PM

and to remember to solder inside, then make your way out (I forgot that while starting the L298 ) since it's easier and you won't run out of space.

isnt it easier to go from bottom to top putting the soldering iron on top of the leg and applying solder to the bottom of the leg?

dellagd · « **Reply #19 on:** April 14, 2009, 07:32:51 PM »

shouldn't I do the IC first because it has 2 rows of pins and can only really be done from one direction?

SmAsH · « **Reply #20 on:** April 14, 2009, 07:33:59 PM »

well, its a matter of preferance really, i would say do the ic first as it has the most pins and is small then the other components in whatever order you choose.

Canabots · « **Reply #21 on:** April 14, 2009, 07:43:37 PM »

Well, I say you follow the instruction booklet about soldering the parts to the board that comes with the kit

Quote from: SmAsH on April 14, 2009, 07:13:11 PM

Quote from: Canabots on April 14, 2009, 07:02:10 PM
and to remember to solder inside, then make your way out (I forgot that while starting the L298 ) since it's easier and you won't run out of space.
isnt it easier to go from bottom to top putting the soldering iron on top of the leg and applying solder to the bottom of the leg?

I actually find it easier to apply the iron where the pin meets the pad so both get heated evenly. Then I apply the solder on the opposite side of the pin. I find that it ensures a nice stong solder joint. I also find it faster

SmAsH · « **Reply #22 on:** April 14, 2009, 07:47:40 PM »

Quote from: Canabots on April 14, 2009, 07:43:37 PM

Well, I say you follow the instruction booklet about soldering the parts to the board that comes with the kit
I actually find it easier to apply the iron where the pin meets the pad so both get heated evenly. Then I apply the solder on the opposite side of the pin. I find that it ensures a nice stong solder joint. I also find it faster

yes that would be a good idea lol, i didnt know it came with a booklet. and to the soldering thats pretty much what i meant. i just find it easier to hold i iron on the top side of the pin as i can see it a lot better than when the irons at the side. now i gotta go finish up some etching

cya round guys.

dellagd · « **Reply #23 on:** April 15, 2009, 10:15:41 AM »

hey how would these motors work they will cut my motor price in half.
http://www.solarbotics.com/products/gm3/specs/

Razor Concepts · « **Reply #24 on:** April 15, 2009, 10:19:39 AM »

43RPM... it will work (plenty of torque), but it will be kind of slow.

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Author Topic: motors / motorcontrolers for a 2 powered wheel, 2 lb robot (Read 2717 times)

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