Modelling an elevator using Object-Oriented Analysis and Design [closed]

Answer 1

Detailed Answer:

http://www.angelfire.com/trek/software/elevator.html

Answer 2

I've seen many variants of this problem. One of the main differences (that determines the difficulty) is whether there is some centralized attempt to have a "smart and efficient system" that would have load balancing (e.g., send more idle elevators to lobby in morning). If that is the case, the design will include a whole subsystem with really fun design.

A full design is obviously too much to present here and there are many altenatives. The breadth is also not clear. In an interview, they'll try to figure out how you would think. However, these are some of the things you would need:

1. Representation of the central controller (assuming there is one).

2. Representations of elevators

3. Representations of the interface units of the elevator (these may be different from elevator to elevator). Obviously also call buttons on every floor, etc.

4. Representations of the arrows or indicators on each floor (almost a "view" of the elevator model).

5. Representation of a human and cargo (may be important for factoring in maximal loads)

6. Representation of the building (in some cases, as certain floors may be blocked at times, etc.)

Answer 3

Donald Knuth's The Art of Computer Programming Vol.1 has a demonstration of elevator and the data-structures. Knuth presents a very thorough discussion and program.

Knuth(1997) "Information Structures", The Art of Computer Programming Vol. 1 pp.302-308

Answer 4

Thing's to be Consider While Designing the Elevator System,

Elevator
Floor/Location Identifier
Number of steps
Rotation speed
Daterange
InstallationDate
MaintainenceDate
Department Identifier
AllowedWeight
Detail / Description
Poison Ratio (Statistics)
Start
Stop
SetDirection
SetRotationSpeed
EmergencyStop = Stop + Alert
EmergencyAccidentSenser Handler

Each button press results in an elevator request which has to be served. Each of these requests is tracked at a global place

The number of elevators in the building will be determined by the user. The building will contain a fixed number of floors. The number of passengers that can fit into the elevator will be fixed. The passengers will be counted as they leave the elevator at their destination floor. The destination floor will be determined using a "random" Poisson interval. When all of the passengers in the elevator have reached their destination floors, the elevator will return to the lobby to pickup more passengers

Answer 5

See:

Lu Luo, A UML Documentation for a Elevator System
Distributed Embedded Systems, Fall 2000
Ph.D. Project Report
Carneghie Mellon University

link

Answer 6

Main thing to worry about is how would you notify the elevator that it needs to move up or down. and also if you are going to have a centralized class to control this behavior and how could you distribute the control.

It seems like it can be very simple or very complicated. If we don't take concurrency or the time for an elevator to get to one place, then it seems like it will be simple since we just need to check the states of elevator, like is it moving up or down, or standing still. But if we make Elevator implement Runnable, and constantly check and synchronize a queue (linkedList). A Controller class will assign which floor to go in the queue. When the queue is empty, the run() method will wait (queue.wait() ), when a floor is assigned to this elevator, it will call queue.notify() to wake up the run() method, and run() method will call goToFloor(queue.pop()). This will make the problem too complicated. I tried to write it on paper, but dont think it works. It seems like we don't really need to take concurrency or timing issue into account here, but we do need to somehow use a queue to distribute the control.

Any suggestion?