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Intelligent Indian Elevators

By Clay Breshears (Intel) (196 posts) on August 6, 2007 at 11:25 am

While staying at the Shangri-La Hotel in New Delhi, I was riding up to my room one evening and noticed that the elevators (Otis 300VFE) were being hailed as "The Intelligent Elevator". I thought nothing of this at the time, passing it off as mere marketing hype.

One morning as I waited on my colleague to join me for breakfast, I watched the floor indicators of the four elevators at the 18-story hotel. When there were no requests for the elevator, I relaized that the cars set themselves at fixed locations. One was at the lobby, one on the fifth floor, one at the tenth, and the fourth at the fifteenth. From this configuration, when a passenger entered the elevator at the lobby and went to the eighth floor, the car parked at floor 5 came down to the lobby and the car that had gone to the 8th floor settled back down on the fifth floor.

This all got me thinking back to when we studied disk fetch strategies in Operating Systems. We wrote a simulation to determine the best request handling strategies with regards to the best way to move and the best place to park the disk head when not in use. By putting an elevator car at every fifth floor, when there were no calls to be serviced, any request from a guest would require that a car move no more than three floors to meet that guest. Plus, the system could automatically rebalance the car locations to provide this minimal wait time.

Once I had observed the elevators for a few minutes and realized what was going on, I had to admit that the tagline wasn't just marketing hype. With my room on the 16th floor during this stay, I was always nice to have an elevator make a quick appearance, rather than have to wait for one to travel the whole 16 floor between me and the ground. It was especially pleasant to see something from my CS background being applied to a real-world situation.

Picture is me at the India Gate in New Delhi.

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Comments (3)

August 6, 2007 6:39 PM PDT Gunjan Rawal

Great picture Clay! And a very nice post :-)I did observe that the elevators always took the same amount of time to get to a floor, but did not think of the intelligence behind it...

September 6, 2007 8:13 PM PDT David Stewart (Intel) Total Points: 12,570 Black Belt

I always wondered why it was that the elevators at the Kerry Center hotel in Beijing (another Shangri-La hotel) always seemed to be really quick to my floor. Must be this "intelligent" behavior. The elevator algorithm is a good one in disk I/O schedulers, I usually remember it reordering the request queue so that the head travels as much in one direction as it can before switching directions. Of course, when high performance applications eventually all switch to solid state disks, these algorithms will be pretty much moot. :-)

September 11, 2007 6:12 AM PDT Clay Breshears (Intel) Total Points: 30,566 Black Belt

While I've been to Beijing twice, I've not stayed at the Kerry Center. I am going to be in Shanghai and Hangzhou next week, but we won't be staying in a Shangri-La hotel in either place. I wonder if these elevators are only in use overseas. Maybe I should check out the Otis Elevator website to see if there is any information on this model and where it might be found.

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