Many elevator models are controlled by a computer system that tells them what to do. The computer needs to know basic information, including where passengers want to go, where each floor is, and where the elevator car is. It also considers the weight of the passengers in the car to ensure safety.
The easiest part is figuring out where people want to go. The computer gets this information when people press the up and down buttons on each floor and the numbered buttons inside the elevator car.
One of the most common ways for the computer to know where the elevator car is located in the shaft is by using a light sensor or magnetic sensor on the side of the car that reads a series of holes located on a long vertical tape in the elevator shaft. The computer counts the holes as the elevator moves, which tells it where the elevator is in the shaft. The computer controls the speed of the motor to make the car slow gradually as it approaches a floor, ensuring a smooth ride.
Computers have to follow strategies to keep elevators running efficiently. An older system does this by not reversing the elevator’s direction until all of the passengers traveling in one direction have been delivered to their destinations. An elevator car that is traveling up will not begin to travel down until all of the passengers who are traveling up have gotten off. Then it will descend to pick up passengers who are going down.
More modern systems can take into account factors such as traffic patterns. They know which floors are most popular at specific times of day and use this information to transport passengers as efficiently as possible. In systems with multiple elevators, the computer will direct cars based on the position and direction of other cars.
A new technology allows passengers in a lobby to request a specific floor, rather than merely pressing an up or down button. The computer groups passengers according to their destinations and tells them which elevator will get them to their destination the fastest. This can speed up travel times for passengers, especially in tall buildings.
Most elevators also have load sensors in the floor that tell the computer when the elevator is near its weight limit. The computer will not allow the elevator to pick up more passengers until some have gotten off. If the car is filled beyond its weight limit, the doors will not close until some of the weight has been removed. Load sensors are an important elevator safety feature.