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Author Topic: Chosing DC Motors!  (Read 682 times)

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Offline SulemanTopic starter

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Chosing DC Motors!
« on: January 01, 2012, 11:01:43 PM »
Hi guys!

We're trying to build a fast maze solving / line following robot, and we're facing a problem in chosing motors,we've built small robots before, but they were of the "off-theshelf-toy-car-motor" type, this time we want to learn more about chosing motors, AND we
want some pretty zippy motors.

Our robot's weight is around 5 kg, and the size is 25x25x30cm (width x length x height) , it will travel only on a smooth and level surface, we have two drive motors with wheels directly attatched to the motors (its a differential drive robot), we do not plan on building a gearing system (so we need a geared motor) and our price limit is around 50-55$ per motor, the motors should be preferrably 12v, but we can go up to 24v. Our desired speed is somewhere along the lines of this thing:

NERC 2011 infinity form c@se(fastest robot in nerc 2011)


We've read up on motors , torque ,stall current, what all the stuff given in the motor parameters means, but we still cant decide which motors to chose, so what motors wll you guys recommend for our application. (We're currently using an H-bridge L298, but we're thinking of switching over toa custom made MOSFET hbridge because the L298 heats up too much with the kind of speed we want).

Currently, were looking at these motors, but we cant figure out if theyll work for us or not, and we dont want to order until we have confirmed that they're the type of motors were actually looking for:

http://www.robotcombat.com/products/0-BHG31.html

http://www.robotcombat.com/products/0-PD27M.html (A bit TOO powerful maybe? AND, a 35 A stall current! We're definittely going to need MOSFETS for these)

Feel free to recommend any other motors as well, any and all advice, critiscism will be appreciated
« Last Edit: January 01, 2012, 11:04:32 PM by Suleman »

Offline Soeren

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Re: Chosing DC Motors!
« Reply #1 on: January 02, 2012, 05:23:08 PM »
Hi,

We're trying to build a fast maze solving / line following robot, [...]

Our robot's weight is around 5 kg, [...]
You know the relationship between weight and "zippyness" is a square one, right?
This mean that if you halve the weight it will be 4 times as "zippy" and while that may be impossible for you, remember that each little weight reduction you are able to make will count.


[...] Our desired speed is somewhere along the lines of this thing:
Give us a speed in m/s or whatever, not a video please - our time can be spend on better stuff than analyzing semi-bad videos :)


We've read up on motors , torque ,stall current, what all the stuff given in the motor parameters means, but we still cant decide which motors to chose, so what motors wll you guys recommend for our application.
[...]
Currently, were looking at these motors, but we cant figure out if theyll work for us or not, [...]
Those motors are very different, so perhaps you should read a bit more ;)

The main parameters you need to establish is weight (not just a loose estimate), wheel size, top speed and acceleration.
Without these numbers, you (or anyone else) won't be able to select a suitable motor.


Feel free to recommend any other motors as well, any and all advice, critiscism will be appreciated
Feel free to give us the data without which nobody can help :)
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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