Input, controller, actuator, controlled object, control quantity, output,

The infrared detector sensed that someone was approaching. The "microcomputer" (calculation part) that converts optical signals into electrical signals and transmits them to the automatic door-the input is electrical signals. The controller is a "microcomputer"

Then, the controller sends instructions to the motor, which will start, open and open the door. The actuator is a motor, the controlled object is a door, the control quantity is an electrical signal, and the output is a door switch.

This thing is still to think and understand by yourself. Just repeat it several times.