9 feedback and control

Feedback and control systems include sensing, computation and actuation.
Sensing, means sensing part of the environment.
Computation, taking the sensed input and figuring out what action to do.
Actuator the action that you do as a result of the sensing

Some real life examples of feedback and control systems are found in the bathrooms.
These are some examples
Automatic hand dryer:
They sense the presence of your hands in the dryer, probably with ultrasound and then they turn on the dryer as your hands are in there, and turn it off when you aren't there
Automatic flush toilets:
These can be seen in some airports. They sense movement away from the toilet.  They don't flush when something approaches the sensor but when people leaves the toilet, they know to flush the toilets. The actuation is probably unplugging a plug to push water into the toilet bowl
automatic lights:
these lights sense any movement in the room.  When they sense movement, they turn on the lights, and then they also compute a time from the last time that they sense movements. and then cut the power to the lights to turn off the lights.
automatic water faucet:
they sense when there is a hand placed underneath the faucet and during that time, they let water run over your hands.   This is probably done with a sensor that senses distance and position of the hands and anytime something is within that range of distance and position(that should match up with just below the faucet), then it knows to turn on the water, but only during that time for which that is true.

automatic soap dispenser:
This is like the automatic water faucet, it does not dispense soap for as long as you hand is underneath it.  As soon as it senses that something is underneath the dispenser, it dispenses one serving of soap and then it waits for the next time that something comes into the correct position and distance (underneath the soap dispenser)

Automatic paper towel dispenser:
This is like the soap dispenser, except that it notices motion at a certain position and distance away from its sensor, and then dispenses one serving of paper towels.


Additionally a lot of things relating to driving and cars feature feedback and control.
Car doors in motion :
Cars will sense when it is moving and when it is moving it will automatically lock the doors to the  car such that you can't accidentally open the doors to the doors.

oil lights
oil lights senses the level of gasoline and displays it. once the level of oil reaches a critical point, then it turn on an indicator light that says you might want to add oil

check seat belt:  the car senses if there is something of significant weight in the front seat and senses if the seat belt in the front seat is buckled.    If there is something of significant weight in the front seat (indicating a person and not )




pedestrian crossings:
that sense when there are pedestrians waiting to cross and when they do sense the presence of pedestrians on the pedestrian crosswalk, not just passing by but waiting for a certain amount of time that it keeps track of at a certain location, then it turns the crossing lights to stop car traffic to let the pedestrian cross.   Using Ultrasound seems like a good idea here.

Red light cameras:
They sense when the red light has been turned and they take a picture.  They compute if there is a car in the image, then the camera saves the image of the red light passing car and then

Letting cars pass:
sometimes in the early morning, certain traffic lights at certain junctions will recognize that if there are cars in one direction and there are no cars in the other direction, that they will change the lights for the cars.  They have to sense when there are cars in all four directions in order

Letting ambulances pass:
lights can sense when there is an ambulance or a firetruck passing through and change the lights such that the lights are green for the firetrucks and red for potentially interfering lanes


Computers:
will automatically shut off if you haven't interacted with it for a certain time.
It senses the lack of keyboard or mouse or touch pad inputs.  It calculate how long that since the last interaction input, and if it is more than a certain length of time, its actuation is to lock your screen and turn off the screen, both to protect your privacy and to save power on the light intensive screen.