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Topic: The Making of a Robot including Mcu for less than $20 (Read 3050 times) previous topic - next topic

_Gareth_

Nov 23, 2012, 04:58 pm Last Edit: Nov 23, 2012, 05:18 pm by _Gareth_ Reason: 1
This project was devised to show how easily it is to make a robot on limited funds.
Video of Build process :-
http://www.youtube.com/watch?v=fudOM3J5goE
It is a good "Starting Off" Robotic platform as it can be easily changed and transformed.

This is just the start of the project and there are many additions planned for it.

It is a cross platform base, meaning that any micro computing unit (Brain) can be used ie. Arduino Atmega range, Propeller or Picaxe.
Due to its low cost i foresee me building a "Swarm" of them .....this one is already the second.
The first one is here :-
http://www.youtube.com/watch?v=AWbuSU7ebhg
http://www.youtube.com/watch?v=zoB0fWV7iAw

The base uses Geared Stepper motors which means that it is very precise and repeatable in its movements. ( forget your sloppy continuous servos )

Regards Gareth

PaulS

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The base uses Geared Stepper motors which means that it is very precise and repeatable in its movements. ( forget your sloppy continuous servos )

A link to those stepper motors and drivers (and wheels) would be nice. What kind of speed are they capable of?

_Gareth_

If you search "5V Stepper Motor 28BYJ-48 With Drive Test Module Board ULN2003" on ebay it will throw up a host of suppliers (I paid £0.99 for mine).
Just check that the driver board is also included.
The speed is as seen in the video second two videos (it is real time) .. If you start pushing up the speed then steps will be missed, however i guess if you are willing to drive them with a higher voltage (mine are 5V) then speed would improve (however at the risk of burning them out ... (the driver board allows splitting of the data and motor supplies).
(With 5Volts  the current is circa 200mA under load/drive and 220mA in stall condition).
Regards Gareth

zoomkat

I've used plastic jar lids for wheels when I didn't have the usual wheels available. Wheel surface slippage will eventually require recalibration of the current bot position. Below looks like a typical "buy-it-now" setup.

http://www.ebay.com/itm/new-Stepper-Motor-Driver-Board-ULN2003-5V-4-phase-5-line-/110956260635?pt=LH_DefaultDomain_0&hash=item19d5822d1b
Google forum search: Use Google Advanced Search and use Http://forum.arduino.cc/index in the "site or domain:" box.

_Gareth_

Yes thanks, the link you give is in the right direction..... there are better deals however its always a balance of how "slow the boat"  is if you know what i mean.

I have also experimented with many types of homebrew wheels , i always fall back to rubber based compounds (grippy) rather than the plastic ones you see around (ie connected to yellow GM motors).

In the last few days i have found a way to use a simple "lego coupling collet" than slips over the motor shaft enabling any type of lego wheel (technic or normal) to be easily used with perfect alignment. Plus factor is that these wheels are easy to come by.  This lego transition part enables the flexibility of adding other standard lego motive parts to the motors (ie cogs and arm followers).

PaulS

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Yes thanks, the link you give is in the right direction..... there are better deals however its always a balance of how "slow the boat"  is if you know what i mean.

Good thing I don't mind wasting a few pennies, or waiting, then. I ordered a pair from zoomkat's link (thanks, zoomkat).

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In the last few days i have found a way to use a simple "lego coupling collet" than slips over the motor shaft

Well? We've got boxes and boxes of Legos around...

_Gareth_

#6
Nov 28, 2012, 09:48 am Last Edit: Nov 28, 2012, 04:09 pm by _Gareth_ Reason: 1
Then this trick is for you PaulS :-
Take one of these Lego cross axle extensions :-

and cut these two lugs out down to the middle of the cross axle extension (not an easy task :smiley-eek:)

Then push fit the cross axle extension onto the motor shaft and enjoy the flexibility that it brings.... :D

_Gareth_

Morse code anyone........

Port and Starboard indicators fitted...

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