The end effector is the component of the CNC machine designed to interact with the world. In this application, the end effector actuator consists of a pen pulled towards the work area by a spring (or pulled away from the work area by a motor), as shown in Figure 2-2. The spring ensures there is sufficient force for the pen to draw when pressed down while preventing so much force that it catches on and rips the paper.
When the actuator pin is logic high, the pen can be pulled towards the work area by the spring. When the pin is logic low, the motor is activated and causes the pen to be pulled away from the work area.
Figure 1. Pen Actuator
