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Elevator Scheduling

Elevator Scheduling. Lingfeng Luo Zhao Han. Elevator Scheduling Problem. Elevator as a control System Behavior depends on programmed algorithms Different solution depending on building type and number of elevators working together Assignment of job External elevator request

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Elevator Scheduling

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  1. Elevator Scheduling Lingfeng Luo Zhao Han

  2. Elevator Scheduling Problem • Elevator as a control System • Behavior depends on programmed algorithms • Different solution depending on building type and number of elevators working together • Assignment of job • External elevator request • Internal floor request

  3. The Building Setting: 15 floor building 2 elevators Goal: Simulate and analyze three major elevator scheduling algorithms by JAVA Use simulation results to find optimal algorithm.

  4. Tools we used • Use JAVA to program different elevator scheduling algorithms. • Use Excel to analyze simulated results and plot chart.

  5. Algorithm A • FCFS ( First come first serve) • Elevators work depends on the order of every request. The first one who sends the request can take the elevator first.

  6. Algorithm B • SSTF- Shortest Seek time first • It will find out which floor is the closest to the elevator. Then, the elevator goes to that floor, and search the next requested floor according to their distance.

  7. Algorithm C • Scan • SCAN makes elevators moving from top to the bottom. Elevators turn back when they reach the top or the bottom.

  8. Performance Metrics • We will evaluate these metrics below for simulated outcome of 3 different elevator scheduling algorithms. • Waiting time of a client: the time in between the client makes a outer request till he gets to the destination floor • C: Total passenger carried in given time interval.

  9. Results – Original Data (FCFS)

  10. Imperfections of the programand things need to improve • 1. the arrival rate is the same for day and night, hour to hour. • 2. requested rate is the same on every floor • 3. the client is always patient • 4. no interface

  11. Limitation of each Strategies • FCFS: not efficient, slows down the process for accessing the floor than it must • SCAN: takes longer for the average request, (won’t starve the process for the sake of others • SSTF: leave some request for very long time

  12. Result Pattern

  13. Avg Waiting Time

  14. Thank you! Questions

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