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Another Beginner Here.

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Tr3y:
I'm just another person that is interested in Robotics and would like to get started as soon as possible.

I've been looking at this site for the last couple days, reading everything about making a robot.  From the different things I have heard, I have put together of what I think is somewhat of a Beginner Robotic Project :)

If you do not mind to take the time and help me, I would appreciate it greatly.


1 Base
   Already Supplied 
      Free

2 Wheels
   Already Supplied
      Free

3 Motor x2
   http://www.superdroidrobots.com/shop/item.asp?itemid=373
      x2 = $37.90
   
4 Batteries x2
   http://www.onlybatterypacks.com/showitem.asp?ItemID=10399.7
      x2 = $12.00

5 Micro-Controller ( One of the 2 )
   http://www.parallax.com/detail.asp?product_id=BS2-IC
      $49.00
   With Program Equip. *I think*
   http://www.parallax.com/detail.asp?product_id=28803
      $99.00

6 Sensors - Photoresistors
   http://www.radioshack.com/product/index.jsp?productId=2062590&cp=&origkw=Photoresistor&kw=photoresistor&parentPage=search
      x5 = $2.79   

7 Programming Software
   Listed with Micro-Controller

8 Misc. Materials 
   Already Supplied
      Free

Total Project Amount
   $151.69 + Shipping


*** The only thing I seem to be concerned in is the Programming and the Microcontroller, would you recommend something else then I posted above :s ?

Am I doing something wrong here.  This seems like a cool project I can do over the Summer.  Hopefully some time in the next 3 weeks I can start getting stuff together and begin building when I get out of school. 

Also do you believe this is a better way to learn more about robotics, or should I start out with a Kit?  My goal right now is to just learn the basics, and then start building up to more complex.  Whatever seems the best way to go please let me know :)


*Edit:  Also forgot to mention that I planned on making a 4-wheel robot.  I dont think it will be to hard, but kind of confused to what makes the two-wheels in the front move left and right.  Well, I understand how it will work, but what device do I hook to the Microcontroller that enables it to move back and forth.  I must be doing something wrong when thinking about this :o

*Edit Again: Just relized, after reading the beginner tutorial you posted again, that the 2 wheel robot is the best way to start out with.  This makes a lot more since to me now.  I still plan on using the 4 wheels, this should still be ok, correct ?

Plan on buying a book today or tomorrow that might help me better understand this kind of stuff ;)

Admin:
A servo is different than a motor.
http://www.societyofrobots.com/actuators_servos.shtml
http://www.societyofrobots.com/actuators_dcmotors.shtml
Just make sure you know the difference. I personally perfer servos just because control is a lot easier. The motors you selected will work fine though.

If you are going to use two motors, I assume you are using differential steering. What you would want is not 4 wheels, but two wheels and a castor. This is my very 2nd robot:
http://www.societyofrobots.com/images/materials_HDPEexample.JPG
The wheel on the far right is just an idle wheel used for furniture. If you used a fixed wheel, it would drag across the ground resisting your robot from turning. Just search the web for castors, there are many many types. You could however, by using a chain, link the front and back wheels together, almost like a tank but without treads. One motor would drive both wheels on a side. It would still be differential drive. I have done that before and it works really well for rough terrain, but as a tradeoff turning requires more energy.

As for batteries, a single lithium ion battery would be 3x better and still cheaper than the battery you chose:
http://www.onlybatterypacks.com/showitem.asp?ItemID=10920.23
http://www.onlybatterypacks.com/showitem.asp?ItemID=10978.23
Voltage and mAh are key. I personally recommend the 2nd battery . . .

You also need a battery charger. Search that site to check out the chargers.
The lithium battery chargers are generally more expensive tho. I think in the next few years lithium ion will be the best battery to use, so probably not a bad idea to just start using them.

Or for a litium ion charger you can do this instead:
"An adjustable power supply that current limits like
http://www.mpja.com/productview.asp?product=9303+PS works just as well. You
set the voltage limit to 4.2v * number of cells, then set the current limit to the cell capacity (1.4a for your cells) it will constant current charge until it reaches 4.2v/cell then constant voltage charge until its full, which is when the battery capacity has dropped to zero. Thats the recommended charge profile for lithium and lead acid batteries anyway." (quote from my friend, I havnt tried it yet)

For your microcontroller, you will need a programming board. Basically a way to hook it up to your computer to be programmed. Paralax should offer one. Just look around, it will be obvious when you see it.

You also need a bread board or protoboard to stick your wires in.

Being your first robot, I wish you luck. I totally failed on my first attempt  :P
Whatever you understand the easiest, do. Simplicity is best.

vikram:
hi,

      my name is vikram   I am a student of Mechatronics field  and want to know more about robotics field

      so i can do my undergraduat project on robots.

      I have seen that administrator replies 2 everyone who post messages here.

      I am sure he will help me

dunk:
repling to Tr3y,
you look like you are about to make exactly the same mistake as i did on my first robot.
the motors you are looking at are far too powerfull for a simple first robot.
you will have problems building motor controllers for 24volt motors like these.

for your first bot it would be far better to use either servos like Admin suggests or something like this:
http://www.superdroidrobots.com/shop/item.asp?itemid=408&catid=7
that motor/gearbox combo runs at 3volts but should have enough power to move a small bot around.
it will mean you don't need to put 24volt batteries on board too.

good luck.

Handmixer.com:
Vikram, I am not an expert in this field, and in fact, am also just starting, but I have read a lot of books about robotics and would be happy to share some ideas with you. What sort of functions did you have in mind for your project.

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