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Author Topic: motors / motorcontrolers for a 2 powered wheel, 2 lb robot  (Read 3630 times)

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Offline dellagdTopic starter

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motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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.
« Last Edit: April 13, 2009, 04:40:57 PM by dellagd »
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Offline SmAsH

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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?
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Offline dellagdTopic starter

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« Reply #2 on: April 12, 2009, 06:05:01 PM »
well I really don't know what kind of motor I would need.
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Offline SmAsH

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« Reply #3 on: April 12, 2009, 06:22:02 PM »
well first figure out which motor you need then we can talk.
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Offline Razor Concepts

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« Reply #4 on: April 12, 2009, 06:27:56 PM »

Offline dellagdTopic starter

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« Reply #5 on: April 12, 2009, 08:21:15 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 )?
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Offline dellagdTopic starter

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« Reply #6 on: April 13, 2009, 05:30:42 AM »
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Offline SmAsH

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Offline Canabots

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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?  :P)

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  :D)

Good Luck
« Last Edit: April 13, 2009, 08:50:24 AM by Canabots »
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Offline dellagdTopic starter

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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?
« Last Edit: April 13, 2009, 04:40:18 PM by dellagd »
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Offline robomow

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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

Offline dellagdTopic starter

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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?
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Offline Canabots

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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...
« Last Edit: April 14, 2009, 07:13:19 AM by Canabots »
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Offline dellagdTopic starter

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« Reply #13 on: April 14, 2009, 06:04:31 PM »
how hard would that be to solder, Canabots?
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Offline SmAsH

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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.
« Last Edit: April 14, 2009, 06:29:03 PM by SmAsH »
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Offline dellagdTopic starter

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« Reply #15 on: April 14, 2009, 06:44:21 PM »
ok I think I will attempt it.
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Offline SmAsH

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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 :P
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Offline Canabots

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« Reply #17 on: April 14, 2009, 07:02:10 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  :D) since it's easier and you won't run out of space.
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Offline SmAsH

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« Reply #18 on: April 14, 2009, 07:13:11 PM »
and to remember to solder inside, then make your way out (I forgot that while starting the L298  :D) 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?
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Offline dellagdTopic starter

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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?
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Offline SmAsH

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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.
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Offline Canabots

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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 ;)  :D

and to remember to solder inside, then make your way out (I forgot that while starting the L298  :D) 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  :P
« Last Edit: April 14, 2009, 07:44:56 PM by Canabots »
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Offline SmAsH

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« Reply #22 on: April 14, 2009, 07:47:40 PM »
Well, I say you follow the instruction booklet about soldering the parts to the board that comes with the kit ;)  :D
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  :P
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.
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Offline dellagdTopic starter

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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/
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Offline Razor Concepts

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Re: motors / motorcontrolers for a 2 powered wheel, 2 lb robot
« 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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