Like in Shopko the doors that swing out how do they work. How do they swing out automatically?
There is a sensor that detects someone approaching the door. It could be a switch in a floor mat or an ultrasonic device that receives an echo from an approaching customer. The sensor operates some sort of electric motor that drives a mechanism that opens the door.
Generally speaking there are three components. I don't know how good you are with computers and electronics so I'll try to keep it simple. 1. A sensor- The sensor is what looks out to make sure someone is there that needs the door to open for them. Sensors come in many forms. It could send out sound waves to see if anybody is near by. There could be an LED that sends out a light to a reciever and if the receiver doesn't receive the light it could mean somebody is walking by. And there are many more. 2. The second component is the motor. Once the sensor realizes that door needs to be opened the computer will tell the motor to operate and open door. The motor does all the mechanical work. 3. The computer is the third component. It does all the smart work. Think of the computer as the line of communication betweent the motor that closes and opens the door and the sensor that detects people. The only thing a sensor does is put a voltage depending on what it senses. The computer has to read those voltages and decide what is happening.
Expensive shops have the motor to swing the doors in the floor or wall above the door to not look mechanical. Cheap shops and places that require rapid access for maintenance, like health facilities, put a box above the door and an arm that runs to the door and it is in plain sight. These days the sensor is most often infrared and is in a bar above the center of the door. These are cheaper and more reliable in a noisy environment than ultrasonics. One proof of this is that if you stand still, the door will close because IR works by noticing changes in the heat profile and standing still removes the changes. Ultrasonic sends out a signal for an echo. Finally, there has to some kind of timer to keep the door open for as long as needed but not forever. Most use a small microprocessor to handle this and deal with errors. Many moving doors have current sensors that watch and if there is an increase in power while moving, it is assumed the door is hitting something and reverses or stops.
