Information Technology Reference
In-Depth Information
:S
S
10
[0
;
1]
A
A
Here the two horizontal lines describe the behaviour of
S
and
A
in isolation.
The arrow describes the link between
. Semantically the diagram repre-
sents an implication in the assumption-commitment style: If for a duration of 10
seconds
S
and
A
:S
was observed (
assumption
) then within 1 second a period where
A
holds has to occur (
commitment
). The boxes around
1] indicate that
these are commitments whereas the remaining parts are all assumptions. The
dashed parts of the lines represent arbitrary behaviour of
A
and [0
;
S
and
A
.
4.1 A Real-Time Filter
A technical problem is that sensors may stutter, i.e. issue more than one output
signal when in reality only a single tram has passed the sensor. To avoid wrong
data in the drive controller for the trams a suitable
lter
is needed for each
sensor. We consider here a lter
FES
reading input values
no tr; tr
and
Error
in
out
FES
{no_tr, tr, Error}
{N, T, X}
Fig. 3.
Filter
from the entry sensor
ES
and transforming them into output values
N
(for
no
tram
),
T
(for
tram
)and
X
(for
exception
). This is indicated by Fig. 3 and the
corresponding observables:
in
:
Time
−! f no tr; tr; Errorg
st
:
Time
−! f N; T; Xg
The desired real-time behaviour is shown in the timing diagram in Fig. 4. When
an input
tr
from the sensor
ES
is detected the lter
FES
should (after a reaction
Search WWH ::
Custom Search