CSci 405: Computer Simulation
Spring Semester 2000

Assignment #1
Due Wednesday, 9 February, 11:00 A.M. (Revised)


Prepare this assignment paper by the above deadline in accordance with the instructions given in the Professional Conduct and Assignments sections of the Syllabus .

This assignment may be done individually or by groups of two people.

Consider the following informal specification of an elevator problem. Beginning with an analysis of the text, develop a class model for the problem. Prepare a document that describes your class model, giving appropriate class diagrams using the Unified Modeling Language (UML). The model should identify the classes, their responsibilities (i.e., operations and key attributes), and their collaborations (i.e., the relationships among the classes). You will probably want to use Rational Rose to draw the class diagrams.

Suppose the University plans to build a new M-story building on campus. The building will have N elevators to move people among the M floors. The elevators and control mechanisms are supported by the manufacturer. The internal mechanisms of these are assumed (i.e., given). Your task is design the control software to move elevators between floors in the building. The control logic is subject to the following constraints:

  1. Each elevator has a set of buttons, one for each of the M floors. These buttons illuminate when pressed and cause the elevator to visit the corresponding floor. The illumination is cancelled when the elevator visits the corresponding floor.

  2. Each floor, except for the bottom and top floors, has two buttons, one to request an up-elevator and one to request a down-elevator. These buttons illuminate when pressed. The illumination of a button is cancelled when the elevator visits the floor and then moves in the desired direction.

  3. When an elevator has no requests it enters the standby state. (For example, one possible standby state would be to remain on the last floor it visited with its doors closed.)

  4. All requests for elevators from all floors must be serviced eventually.

  5. All requests for floors within elevators must be serviced eventually, with floors being serviced sequentially in the direction of the elevator's movement.

  6. Each elevator has an emergency button which, when pressed, causes a warning signal to be sent to the site manager. The elevator is then deemed "out of service". Each elevator has a mechanism to cancel its "out of service" status.

Note: Carry out this assignment carefully. You may be asked to write a simulation program in a future assignment. The purpose of the simulation is to help in the design of the building, allocation of space to different purposes within the building, determination of the number of elevators, determination of different scheduling algorithms for the elevators, etc.


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Copyright © 2000, H. Conrad Cunningham
Last modified: Mon Feb 7 10:06:59 2000