Choosing motors for an arduino robot to compete in robocup jnr

[keyboard1333]

Hey Guys!
Me and a friend recently started plans to build a robot using an Arduino Uno to compete in the Australian Robocup Junior Soccer competion.

A friend who has competed in previous years, used 200rpm 12v 1.2A motors.
Do you think that that is enough power to move a robot weighing a couple of kilos rather quickly?
(Like half a meter a second)
If not, what are the specs for the kind of motor that we want?
Thanks, keyboard1333

[newInRobotics]

You didn't mention wheel diameter 

[keyboard1333]

Between 1 & 2 inches.

[newInRobotics]

Then max velocity achievable (without taking friction into consideration) will be between ~0.27 m/s to ~0.53 m/s. It's clear that 1" wheels don't really cut it, hence let's go with 2" wheels.

• Circumference = Diameter * pi
• Velocity = Circumference * RPM

To have acceleration of 0.25 m/s² (to be able to reach 0.5 m/s velocity in 2 seconds) each motor has to be capable of at least 63.5 mN*m torque.

• Force = Mass * Acceleration
• Torque = Radius * Force

You probably don't want to run motors at 100% duty cycle all the time, so to be on a safe side lets say that You want to achieve aforementioned results while running motors at 75% duty cycle. So, max motor RPM has to be at least ~252 RPM and stall torque has to be at least ~85 mN*m.

For what You want, something like 300 RPM 12V 0.39 N*m motor would be more that enough. Of course if plan on using 12V. What voltage are You planning to use?