thanks for the reply Soeren
Here's what I'm thinking as of now:
Find the Ball = 10 IR sensors all around the robot (IR sensors would be connected to a comparator so that I would get a digital output, On or Off)
Navigate around the field and other robots = 6 PING Ultrasonic Sensors . I'd use these sensors to move around so that I get a clear shot of the goal and so I dont run into walls/robots.
Know direction of goal = 1 Compass Sensor
Aim for a goal = 1 CMUcam. Goals are either blue or yellow, so to aim my robot's "kick" I would align myself to the goal so that the middle mass of the goal color ( yellow or blue, depending on what side of the field I'm on) is right about center. Then I'd shoot.
You want to remove any IR filters to make it more sensitive and then add an IR pass filter (that blocks out visible light).
ahh thats what I meant , a pass filter.
Push the IR ball - probably a linear actuator or a spinning motor wheel
A solenoid is the way to go.
A solenoid with a spring is a possibility, but I can't seem to find any small DC solenoids with springs attached. So far I've only found this one - http://www.surplusgizmos.com/Solenoid-12V-w-spring_p_818.html
, but its a bit too big (11cm). I'll keep searching...
Also, if I find solenoids that are rated for 24V, at 12V they will just run at 1/2 the speed and 1/2 the torque, right?