Elevator Scheduling Lingfeng Luo Zhao Han S Elevator

Elevator Scheduling Problem S Elevator as a control System S Behavior depends on programmed

The Building Setting: 15 floor building 2 elevators Goal: Simulate and analyze three major

Tools we used S Use JAVA to program different elevator scheduling algorithms. S Use

Algorithm A S FCFS ( First come first serve) S Elevators work depends on

Algorithm B S SSTF- Shortest Seek time first S It will find out which

Algorithm C S Scan S SCAN makes elevators moving from top to the bottom.

Performance Metrics S We will evaluate these metrics below for simulated outcome of 3

Imperfections of the program and things need to improve S 1. the arrival rate

Limitation of each Strategies S FCFS: not efficient, slows down the process for accessing

Result Pattern 3 Algorithm Comparison FCFS SSTF SCAN 1 3 5 7 9 11

Avg Waiting Time Total Average Waiting Time 275 270 265 260 255 250 245

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Elevator Scheduling Lingfeng Luo Zhao Han S

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

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.

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

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

Algorithm B S SSTF- Shortest Seek time first S 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.

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

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

Results – Original Data (FCFS)

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

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

Result Pattern 3 Algorithm Comparison FCFS SSTF SCAN 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95

Avg Waiting Time Total Average Waiting Time 275 270 265 260 255 250 245 240 FCFS SSTF SCAN

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