Hardware Reference
In-Depth Information
24
m
5
m
4
23
c
3
m
6
c
2
04
20
c
1
c
4
c
7
34
14
c
7
Fig. 15.9
Supervisory controller for cat and mouse from Example
15.22
as a consequence the states in the subgraph rooted in the state (1,0) are made
unreachable (we did not show in the picture the subgraph rooted in (1,0) to keep
the drawing simple).
Delete transitions to previously removed states, e.g., from state (0,3) delete
transitions to (3,3) under
m
6
.
Eliminate unreachable states, e.g. state (1,0) and successors.
2. Step 2: Delete state (0,3) since it is not co-reachable, because after deleting (1,3)
it became a blocking state with no transitions out of it, and delete all transitions
to it.
c
4
and to (0,0) under
What remains is the supervisory controller shown in Fig.
15.9
.
At each state some doors must be closed or open, while the rest are don't cares
conditions (and
c
7
is uncontrollable), as follows:
c
3
D
1
m
5
D
1
c
1
D
c
2
D
c
4
D
c
5
D
c
6
D
,
m
1
D
m
2
D
m
3
D
m
4
D
(2,4):
,
,
m
6
D
(0,4):
c
1
D
c
4
D
m
5
D
c
2
D
c
3
D
c
5
D
c
6
D
,
m
1
D
m
2
D
m
3
D
1
,
1
,
0
,
m
4
D
m
6
D
(1,4):
c
2
D
1
m
5
D
0
c
1
D
c
3
D
c
4
D
c
5
D
c
6
D
,
m
1
D
m
2
D
m
3
D
m
4
D
,
,
m
6
D
(3,4):
c
5
D
0
m
5
D
0
c
1
D
c
2
D
c
3
D
c
4
D
c
6
D
,
m
1
D
m
2
D
m
3
D
m
4
D
,
,
m
6
D
(2,0):
c
3
D
m
1
D
m
4
D
c
1
D
c
2
D
c
4
D
c
5
D
c
6
D
,
m
2
D
m
3
D
0
,
0
,
1
,
m
5
D
m
6
D
(2,3):
c
3
D
0
m
6
D
1
c
1
D
c
2
D
c
4
D
c
5
D
c
6
D
,
m
1
D
m
2
D
m
3
D
m
4
D
,
,
m
5
D
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