In the past two issues of Beanz we have thought a bit about the robotics that goes into building simple elevators. We even created two elevator systems using a stepper motor and Arduino to transport items from the ground on up to the top of a mini treehouse, as well as up the prototype of a more standard elevator shaft. These projects involved a bit of mechanics, some electronics, and a tad of code.
Even though mechanics, electronics, and code are the main components of robotics, these simple elevators are better described as electronics projects than robotic projects. The reason being is that they did not involve sensors and the finished products required too much human involvement to run properly. The line that distinguishes machines such as our simple elevators from robots is a bit fuzzy, but it is generally agreed that robots can make decisions for themselves, without humans controlling them through switches and buttons.
Most elevators today still require a human to push a button telling it what floor to stop at. However through the use of sensors and code, they can decide on their own when they have reached a specified floor. This ability makes them more robot-like than elevators of the past that relied on a human operator who traveled inside the car, telling the elevator when to open and close its doors.
Perhaps the most robotic elevators today are those that run on a system known as Destination Dispatch. Although for over half a century elevator industry lagged behind most others in terms of adopting new technologies, the increase in extremely tall buildings in the 21st century has created demand for more efficient people-transporting systems. From the Burj Khalifa in Dubai, to the Shanghai Tower in China, to the headquarters of Legg Mason in Baltimore, and on to the Marriott Marquis in Times Square, people are now transported up and down much more efficiently than ever before.
So what is Destination Dispatch and how does it work? Destination Dispatch is an optimization technique used in today’s most modern buildings with multiple elevators. It uses an algorithm that groups passengers with similar destinations together in the same elevator. A person using this system types in the floor they wish to travel to before getting into the elevator (as opposed to just pushing the up or down button that most elevators still have outside their doors). Destination Dispatch then quickly assigns the user to an elevator and tells them which elevator to board. Once inside, there are no buttons. The elevator already knows to stop at the floors corresponding to each passenger. Since it figures out which passengers to group together in advance without overcrowding the elevator, this system can increase elevator capacity by approximately 30%, which translates to much shorter wait times.
Our homemade elevator prototypes are still a far cry from the most robotic of elevator systems. And Destination Dispatch is a patented algorithm that we would not be able to replicate even if we had the parts and the technical skill. But those at home interested in designing a slick system to transport figurines up and down the mini-buildings that they reside in might consider adding a distance sensor to a rope-hobby motor-Arduino setup such as those described in the August and October issues of Beanz.
Sparkfun sells the Quiic Distance Sensor, a solder-free, Arduino-compatible, sensor and breakout board (necessary for connecting the sensor to the Arduino), for under $15. By attaching this either to the top or bottom of a homemade mini lift system and making a few adjustments to the code that Sparkfun provides, we get an elevator that stops “on its own” when it is a given distance from the sensor. Those with a bit more experience with wiring and coding can even think through how to add a couple more buttons to the elevator, and if-else statements to the code, so that if a certain button is pushed the elevator stops at a given distance from the sensor (allowing for stops on multiple levels). Although not quite as robot-like as the elevators running on Destination Dispatch, designing and building such a mini lift system would not only be a cool project, but would take you several steps closer to becoming a seasoned roboticist.
How Elevators Changed the World
The Elevator Museum
The Otis Safety Elevator
The History of the Passenger Elevator in the 19th Century
Marriott Marquis, Destination Dispatch video
Elevator System for the Burj Khalifa
Destination Dispatch on Google Patents
Sparkfun Quiic Distance Sensor and Ecosystem