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ESE601: Hybrid Systems. Review material on discrete event systems I. Contents. Examples (5) Transition systems and automata (6) Languages and regular expression (6) Reachability and blocking property (5) Composition of automata (5) I/O automata (5). A vending machine. Insert coin(s)
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ESE601: Hybrid Systems Review material on discrete event systems I
Contents • Examples (5) • Transition systems and automata (6) • Languages and regular expression (6) • Reachability and blocking property (5) • Composition of automata (5) • I/O automata (5)
A vending machine • Insert coin(s) • Choose tea or coffee • Put the cup on the tray • Drink is ready ready cup tea coin coffee cup
Printer data buffer Data in out in in out in out printer Data out overflow in
jam fix out print ready A printer The printer receives data from the buffer, and print it out. Once the printout is ready, the printer is ready to receive new data. While printing, the paper can jam and need to be fixed before the printing process can resume.
A slot machine • Insert coin • Pull handle • Win if the combination is good, otherwise lose. 7 7 7 7 7 win handle coin handle lose
Modeling recap • Events are time-abstract. • Just like modeling of continuous systems, the level of detail is ‘modeler dependent’. • Events are not necessarily equipped with any notion of ‘internal-external’ or ‘input-output’. • Compositionality is possible (to be discussed later). • There can be non-determinism.
Transition systems 4 jam fix out 1 2 print 3 ready
Automata 4 jam fix out 1 2 print 3 ready
Composition of automata a b 1,1 2,2 1,3 1 1 a a a b a a a 3 a 1,2 2,3 2,1 2 2 b
Composition of automata out in 4 jam in out out 1 2 print 3 in out ready overflow in
a a b c 1,1 2,1 3,2 5,1 d 4,2 Example 1 a 1 2 c a c b b d 3 4 2 c Only accessible states b 5