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 ID: 273375
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Slide1
Elevator Scheduling
Lingfeng Luo
Zhao HanSlide2
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 requestSlide3
The Building
Setting:
15
floor building
2 elevators
Goal: Simulate and analyze three major elevator scheduling algorithms by JAVAUse simulation results to find optimal algorithm.Slide4
Tools we used
U
se JAVA to program different elevator scheduling algorithms.
Use Excel to analyze simulated results and plot chart.Slide5
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.Slide6
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.Slide7
Algorithm C
Scan
SCAN makes elevators moving from top to the bottom. Elevators turn back when they reach the top or the bottom.Slide8
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.Slide9
Results – Original Data (FCFS)Slide10
Imperfections of the program
and 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 patient4. no interfaceSlide11
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 timeSlide12
Result PatternSlide13
Avg Waiting TimeSlide14
Thank you!
Questions