I built a robot capable of drawing and writing on a flat surface. You use two servomotors, each attached to an articulated arm. Each arm is made of two articulated segments, connected to a servomotor at one end and to the writing tool at the other end. The position of the writing end of the robot arms is completely determined by two angles controlled by the servomotors.
The computer will run a processing program which tracks the position of the mouse cursor, and send it over to the arduino board. The computer is connected to the arduino board through the arduino's USB cable. The position of the mouse cursor is converted to appropriate angles for the servomotors. The arduino is connected to servomotors through simple wires, Arduino controls the servomotors through another program.
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