Real-world feedback/control systems (psst: its not just magic!)

Identify four feedback/control systems you encounter in your everyday environment.


1. Air Conditioning/Heating System

• sensing mechanism -- the thermometer senses the approximate temperature of the room
• control computation mechanism -- the computation (using closed loop bang-bang control or ) decides if the room temperature is below a certain threshold (say 5 degrees F below the desired threshold)
• actuation mechanism -- the heater/air conditioning unit runs until the air is a little above the desired temperature

2. Seatbelt Warning

• sensing mechanism -- a sensor senses if there is a certain amount of weight in the seat; senses if the seatbelt is locked into the buckle
• control computation mechanism -- using bang bang control, check if the weight is above the minimum threshold and if the the seatbelt is buckled; decides whether the actuating mechanism needs to be turned on or not
• actuation mechanism -- the seatbelt warning light (sometimes this is paired with an annoying sound)

3. Auto-Flush Toilets

• sensing mechanism -- sensor (perhaps one more accurate than the ultrasonic ones we used?) senses the distance of the object directly in front (stall door or person)
• control computation mechanism -- checks if the distance to the object directly in front is below (say, 1 foot) and decides whether to flush or not
• actuation mechanism -- the valves that deal with flushing water (pumping water in and pushing waste out)

4. Light Sensor/Grocery Store Door Sensor

• sensing mechanism -- sensor that could detect body heat (infrared sensor) or a variation on the ultrasonic sensor that senses the distance to multiple objects
• control computation mechanism -- if body heat is detected in the room, tell the light to turn on; if there is a change in the distance to an object, tell the light to turn on
• actuation mechanism -- the light or door motor (bang-bang controlled) on or off