Real Time Systems: Train Gate System II

1
Real Time SystemsTrain Gate System II

• Chieu Wang
• Vincent Ng

2
Current System

• A unidirectional railway track that crosses a one
  way road.
• A single gate at the crossing which may be
  lowered or raised under the control of a
  computer.
• There are two sensors present to detect incoming
  and outgoing trains.

3
Current System
Entry Sensor
Exit Sensor
Gate
4
Processes

• Se represents the entry sensor.
• Sl represents the exit sensor.
• G represents the gate.
• M the monitor that keeps track of the number of
  trains in the area.
• C controls the gate.

5
Train Gate CRSM Communication Diagram
tr

trout
trin
gok
og
cg
M
cont_og
cont_cg
6
Proposed Modifications

• Change to a two track unidirectional railway that
  crosses over a two way road.
• Model will include two gates at the crossing
  which may be lowered or raised that is under the
  control of a computer.

7
Proposed Modifications, Cont

• There will be four sensors in the system
• Two sensors for each track to detect incoming and
  outgoing trains.

8
Train Gate System II
Entry Sensor 2
Gate 2
Exit Sensor 2
Entry Sensor
Gate 1
Exit Sensor
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Details of Proposed Modifications

• Se2 represents the entry sensor on second
  track.
• Sl2 represents the exit sensor on second track.
• G2 represents the second gate.

10
Train Gate II CRSM Communication Diagram
tr
gok
trin

tr 2
og
cg
trout
trin 2
cont_og2
cg 2
cont_cg2
og2
cont_og
trout 2
cont_cg
gok2
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Recommended Implementation and Modeling
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Simplified Modeling Version
13
Advantages

• Existing classes does not need to be modified.
• ie. sensore.java, sensorl.java, gate.java
• Existing classes are easily cloned for reuse.
• Existing timing constraints can be applied to the
  new classes.

14
Disadvantages

• The monitor and controller process require
  substantial modifications to handle the new
  classes.
• Issues with sequence of processing.

15
Difficulties Encountered

• The monitor and controller class required major
  overhaul to accommodate multiple events that may
  occur at the same time.

16
Conclusion

• The modified system will provide a more realistic
  model of a train gate system.
• By incorporating multiple tracks and sensors, the
  model will further reinforce the basic concepts
  of concurrency and synchronization among processes