Author Topic: robot noob  (Read 3897 times)

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Offline serengetiTopic starter

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robot noob
« on: December 08, 2007, 06:41:17 PM »
Hello, I am building a robot for a school project. I need powerful motors for driving and lifting. What is the best way to control a 7.2v gear head motor with a standard transmitter/receiver combo.  Right now I am thinking about a

tamiya esc $40 http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXGMR5&P=7
and a gear head motor. $40  http://www.roboticsconnection.com/pc-51-7-dc-gearhead-robot-motor.aspx
 I don't wish to use a microcontroller and want it to be as simple as possible, like in an rc car. Is there a simpler way than an esc? All I need is basic forward/reverse. I am looking to save every penny because I need at least 3 of these combinations.
Any advice is appreciated

Thanks

Offline cooldog

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Re: robot noob
« Reply #1 on: December 08, 2007, 06:51:01 PM »
do you need more torqe or speed

if you need more speed then use these there not efficant but have great speed

http://www.goldmine-elec-products.com/prodinfo.asp?number=G15885

also get 1 of these ESC instead of 2 on the $40 ones

http://www.dimensionengineering.com/Sabertooth2X5RC.htm

wheels for the motors

http://www.goldmine-elec-products.com/prodinfo.asp?number=G13889
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Offline serengetiTopic starter

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Re: robot noob
« Reply #2 on: December 08, 2007, 09:07:31 PM »
I will need a lot of torque because I am moving a 5-7 lb robot and a 6 lb box on a thin carpet. Speed is not too important, aiming for 0.5 m/s. Are the Denso motors strong enough for the job? Does the sabertooth 2x5 directly connect the receiver to the motors? I do not have enough funds to buy a microcontroller/ bot board.  If possible, I prefer not to have to program anything or fumble with software. If it's really simple I don't mind but my programming knowledge is elementary.

Offline cooldog

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Offline serengetiTopic starter

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Re: robot noob
« Reply #4 on: December 08, 2007, 10:52:25 PM »
thanks for the info, if i don't plug the flip channel into anything, nothing will happen right?
And do you think those motors are strong enough to push 13 lbs of robot + box?

Offline serengetiTopic starter

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Re: robot noob
« Reply #5 on: December 08, 2007, 11:31:22 PM »
how would I connect 2 sabertooth motor controllers to one battery?

Offline cooldog

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Re: robot noob
« Reply #6 on: December 09, 2007, 06:37:23 AM »
y it will take both motors and give u differental drive with just 1 speed cotroller
« Last Edit: December 09, 2007, 06:48:08 AM by cooldog »
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Offline Admin

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Re: robot noob
« Reply #7 on: December 09, 2007, 10:03:06 AM »
you can only know if your motors are powerful enough for your robot by calculating it:

http://www.societyofrobots.com/RMF_calculator.shtml

Offline serengetiTopic starter

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Re: robot noob
« Reply #8 on: December 09, 2007, 12:41:22 PM »
I will be controlling 4 motors independently, 2 for driving, and 2 for a shovel mechanism, so I would need 2 2x5 controllers. Also, I am limited to 1 7.2v 6-cell battery pack, so it would have to power both motor controllers. Are there ways to power both with 1 battery?

Offline Rebelgium

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Re: robot noob
« Reply #9 on: December 09, 2007, 12:47:31 PM »
Quote
I will be controlling 4 motors independently, 2 for driving, and 2 for a shovel mechanism, so I would need 2 2x5 controllers. Also, I am limited to 1 7.2v 6-cell battery pack, so it would have to power both motor controllers. Are there ways to power both with 1 battery?
Just connect the two motor controllers in parallel...
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Re: robot noob
« Reply #10 on: December 09, 2007, 12:48:38 PM »
Why not use four servos, receiver, and RC transmitter?

Quote
Also, I am limited to 1 7.2v 6-cell battery pack, so it would have to power both motor controllers. Are there ways to power both with 1 battery?
Ok so most servos shouldn't go about 6V so maybe ignore my top comment, but you can easily use one battery for all DC motors.

Offline serengetiTopic starter

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Re: robot noob
« Reply #11 on: December 09, 2007, 02:47:39 PM »
aren't most servos rated at 6v? Is it possible to remove the servo casing, and replace the servo motor with a dc gearhead motor? I would save a lot of money because I have several cheap futaba servos. Can the servo circuits control the gear head motor? What 7.2v motors do you guys use? I calculated my RMF to be around 0.4-0.6

Offline ed1380

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Re: robot noob
« Reply #12 on: December 09, 2007, 03:10:13 PM »
the servo's are rated at 6v cause the controller circuit can't take more.

motors easily take extra voltage, they just wear out faster.
electronics on the other hand release their magic smoke
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Offline serengetiTopic starter

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Re: robot noob
« Reply #13 on: December 09, 2007, 03:22:55 PM »
thanks ed, does anyone have any 7.2vdc motor/gear head motor recommendations? RMF between 0.4 and 0.6
hopefully under $45 each

 


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