Question about GP2D12 Sharp sensor and Gear Motor

hallo sorry if the question sound stupid but i'm still new in robotic. i'm hoping to build a simple robot using arduino and a few part that i have .my question is can Gear motor been used a the driving force of my robot rather than 2 continuous rotation servomotors...and i have done some googling but not sure how to use the IR sensor(GP2D12 Sharp) and is it the suitable sensor for my robot to avoid obstacle,wall and etc...opinions and sugesstion are hugely welcome thanks :) :) :) :)

Yes, a gear motor can be used instead.

The continous servo motors are usually used because they have the motor drivers built in. The Arduino cannot give enough current to drive motors directly, so if you use gear motors, you will have to use a motor driver.

Two good choices for the motor controller: http://www.ladyada.net/make/mshield/ http://www.solarbotics.com/products/k_cmd/

The Sharp GP2D12 is a fairly standard sensor for your first robot. Basically you give it +5V and Ground, the third lead you wire into one of the Arduino's analog ports to read the value. The number you get back should typically vary between 0 and 512 with lower numbers meaning longer distance sensed.

Have a read over this page for some other information: http://letsmakerobots.com/node/2164

ic..thanks for the link but i'm not living in US,that make a bit hard to find the motor driver,nevertheless i have found local site that sell the motor driver

http://www.cytron.com.my/listProductGroup.php?pid=LiAOLjs2MxsyGisLCBE8DaezWYlKcKCCn2qHJWqd3IE=

my next question(sorry for asking too much question,still a noob) is which one of this driver should i use..should i buy two for two gear motor...thnaks again for your help.truly preciated it

This is just my opinion but those drivers feel too expensive for a first robot. If you have access to simple parts you can easily build an h-bridge to control your gear motors as long as they are not too large.

I'm in the middle of the same project and I found this design for an h-bridge which I really like for small gear motors.

http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/bjt-circuit.html

You connect it to three pins on the Arduino. One for forward, one for reverse, and one of the PWM pins to control speed. If you use two motors, one for each drive wheel (the recommended design for first robots) you need two of these, one for each motor.

There are a lot of similar designs out there and there are also integrated circuits which contain all of the parts of the motor driver in one package. As long as you keep it small you don't need to spend a lot of money on a motor driver (yet). ;)