Title: Requirements%20Specification%20of%20an%20Automotive%20System%20with%20Hybrid%20Sequence%20Charts
1Requirements Specification of an Automotive
System with Hybrid Sequence Charts
- Radu Grosu
- CIS University of Pennsylvania
- Ingolf Krueger, Thomas Stauner
- TU Muenchen
2Motivation
- The design of hybrid systems is a difficult task.
One has to consider many different aspects like
data, behavior, architecture and distribution. - Moreover it usually involves people from
different engineering disciplines. - Many modern SE methods like UML, ROOM and SDL
recommend the use of visual specifications.
3Motivation
- In the projects BeQuest at TU Muenchen and CHARON
at Upenn we developed HyCharts, a visual design
language supporting the hierarchic specification
of architecture and behavior of hybrid systems. - The aim of this work is to complement HyCharts
with HySequenceCharts, a visual requirements
language supporting the hierarchic specification
of interaction between hybrid systems.
4Electronic Height Control System (BMW)(Informal
Requirements Specification)
- Whenever the chassis level is below a certain
bound, a compressor is used to increase it, - If the level is too high, air is blown off by
opening an escape valve, - The chassis level is measured by sensors and
filtered to eliminate noise, - The filtered value is read periodically by a
controller which operates the compressor and the
escape valves and resets the filter when
necessary, - A sensor tells the controller whether the car is
in bend (in a curve).
5EHC Architecture
bend
aHeight
sHeight
fHeight
Filter
D
dReset
reset
EHC
6EHC Description by Trajectories
sHeight
fHeight
aHeight
reset
time
t
t
t
7EHC Description by Timing Diagrams
8EHC with Hybrid Sequence Charts
D
Filter
Control
d2i
t_o
reset
set
dReset
9Basic Segment of a HySC
A
B
C
input x1,..,xi output y1,..,yj local z1,..,zk
i1 -gt
im-1-gt
i1
s1 cond1
im
...
o1
on
...
im-gt o1 .. on
sm cond2
B
10High Level Sequence ChartsEHC-Root
11High Level Sequence Charts(outBend)
outBendC
i2i
i2o
o2i
o2o
12High Level Sequence Charts(i2o and o2i)
i2d
d2i
u2i
13Basic Sequence Charts(i2d)
D
abv
14Conclusions
- We introduced a new visual requirements
specification language HySequenceCharts for
describing interaction between hybrid systems. - HySequence charts can be advantageously used in
the early phases of the development process. - In particular, in the requirements capture phase,
they improve the dialog between customers and
application experts. - The semantics for HySC is very different from the
well known MSC. Most notably, we use shared
variables and a global continuous clock.