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Author Topic: Building A Robot (Please help a beginner)  (Read 753 times)

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Offline chimpfunkzTopic starter

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Building A Robot (Please help a beginner)
« on: December 01, 2011, 08:36:21 PM »
Hey guys,

I'm a high school student, and I'm starting out building a robot based off of arduino, and I could really use some help with the electrical aspect of building a robot. Basically, the goal for this robot is to A) be able to follow a black line through a course and B) find an object after finishing the course. This would all be autonomous. Any feedback would be helpful.


Here are the components I plan on getting:

Arduino Mega 1x
Treads instead of Wheels 1x (http://goo.gl/TBmA0)
Twin motor gear box 1x (http://goo.gl/LFoyX)
PWM Motor Controller 1x (http://goo.gl/veCxE)
Ultrasonic Sensor 2x (http://goo.gl/bwxvT)
Light sensor Array (http://goo.gl/2j1q0)

The twin motor gear box would be wired to the PWM controller, which would connect to the Arduino chip. The sensors would all also connect to the Arduino chip. I had a few concerns about this setup, which I hope can get answered here.

1) The specs for the motors are 1.5-4.5 volts with .66 amps which would provide us with a torque of 4.6 g*cm. The PWM controller we were planning on buying seems to supply only between 12-55v at a minimum of 3 amps. Would this present a problem, and is the torque provided by the motor sufficient for moving a sub-1/2 pound robot?

2) Is there even a need for a PWM controller, or is the motor's electrical needs low enough to be powered from the arduino chip itself?

Thanks for the help

Offline newInRobotics

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Re: Building A Robot (Please help a beginner)
« Reply #1 on: December 02, 2011, 02:35:38 AM »
1) The specs for the motors are 1.5-4.5 volts with .66 amps which would provide us with a torque of 4.6 g*cm. The PWM controller we were planning on buying seems to supply only between 12-55v at a minimum of 3 amps. Would this present a problem, and is the torque provided by the motor sufficient for moving a sub-1/2 pound robot?
There will be a problem, as controller mismatches voltage of the motor. By any chance You can link us to the motor controller You want to use? To answer torque question, we need to know radius of wheels You plan to use.

2) Is there even a need for a PWM controller, or is the motor's electrical needs low enough to be powered from the arduino chip itself?
To start with, Your microcontroller can probably supply around 40mA (max) per pin and that is way less than 660mA. Power You get from uC is logic level only, therefore should be used for logic operations only and NOT to drive inductive loads. You can buy something like L298 Dual H-bridge driver and for diodes to have motor driver circuit for relatively low price and not too much soldering  ;)
"Computer games don't affect kids; I mean if Pac-Man affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music." - Kristian W

Offline chimpfunkzTopic starter

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Re: Building A Robot (Please help a beginner)
« Reply #2 on: December 02, 2011, 08:23:23 AM »
Thanks for the advice. To answer your questions,
We were planning on using treads instead of wheels, with the tread being a total of about 14 inches in length, in laid out in a flat line.
The PWM Controller we were planning to use is this one: (http://goo.gl/veCxE)
For the L298N chip, would that be all you'd need for driving  the 2 motors, or would you need something else as well?

Again, thanks for the help.

Offline newInRobotics

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Re: Building A Robot (Please help a beginner)
« Reply #3 on: December 02, 2011, 01:46:08 PM »
We were planning on using treads instead of wheels, with the tread being a total of about 14 inches in length, in laid out in a flat line.
You'll still have wheels (used to support threads), I need measurements of main wheel (the one that spins the thread).

For the L298N chip, would that be all you'd need for driving  the 2 motors, or would you need something else as well?
Well, if You have a look at the datasheet of L298N, somewhere in it You should find circuit diagrams. As You'll see, You also need 4x Diodes. L298N is a dual H-Bridge - meaning that it can drive 2 motors.
"Computer games don't affect kids; I mean if Pac-Man affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music." - Kristian W

 


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