mechanical components used in Botball are Lego Technic bricks. The electrical components have included a variety of robot controllers, of which each team's kit contains two (enabling them to build two fully autonomous robots out of each kit), as well as a number of different sensors and motors. Robot controllers used in Botball KIPR Wallaby iRobot Create, with an XBC or CBC attached. Previously used: Handy Board, with and without the expansion board Lego RCX, v1 and v2 XBC – v1, v2 and v3 CBC – v1 and v2 KIPR Link Sensors and motors Motors Servo motors In Botball, servo motors are generally used to power an arm or attachment on the robot. They are standard hobby servos, commanded to a position using a standard pulse-width signal as for remote-control cars and airplanes, but in this case the signals are generated by the CBC (or earlier controllers). The servos have an angular range from 0 to 180 degrees and provide motor torque to hold the commanded position. Servos can be calibrated from a special control screen on the CBC w/o any programming to test/adjust their mechanical positions for a desired angular command. Electric DC motors In Botball, the electric DC motors are generally used for powering wheels. Using the Wallaby, however, they can be commanded to run at an accurate speed and stop at a precise rotational position. This is provided at the operating system level in the CBC by periodically sampling the EMF as the motor turns and adjusting the power. The user code only needs to specify the desired speed (and stopping position, if required) using motor functions. Sensors Passive sensors Touch sensor A touch sensor detects when the sensor is hit. Light sensor A light sensor detects light. Light sensors are used in the beginning of the round when a bulb lights up to signal the beginning of a round. Color camera In Botball, the camera is used to keep track of moving objects or move to objects. The camera can track the center of areas (or "blobs") of color (this is called the "blob tracker"). The blob coordinates can, in turn be used to point an arm, or to guide the robot to the object, using a guidance program. IR break beam sensor This sensor uses a beam passing between an emitter and receiver to test for small obstructions. Active sensors Infrared emitter/receivers Sonar sensor These