Image Processing Reference
In-Depth Information
Hardware
model
Comm.
timing
Assignment
model
Function
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Split
Schedule export
Partial
function
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Appl.
timing
Software
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FIGURE .
OEM-supplier development process.
functional model describes the functions of the system and their structure consisting of subfunctions.
As subfunctions have to exchange information in order to provide the intended function output, the
functional model inherently also defines the signals that are transferred from one subfunction to
others. he functional model is complemented by the architectural model, which defines the system
topology and the ECUs that are present in the system. he mapping between these two models results
in a concrete system architecture for a particular system in a particular vehicle. his is described in
the distributed functional model.
Based on the distributed functional model, the OEM performs communication scheduling. During
this operation, signals are packed to messages, which in turn are scheduled for transmission at a
specific point in time. Communication scheduling concludes the global design steps and thus the
OEM's tasks.
The suppliers base their local design steps on the global information given by the OEM. The
so-called split of the distributed functional model tells the supplier which functions or subfunctions
the ECU has to perform, that is his responsibility. he supplier conducts software architecture design
and creates the software model for each function or subfunction. The resulting list of processes is
scheduled for the ECU taking into account local constraints as well as the global constraints defined
in the communication schedule.
Note that for performing the local design, the supplier solely requires parts of the global informa-
tioncreatedbytheOEMaswellashisownknowledgeontheECU.Inprinciple,thesuppliersdonot
influence each other.
16.4.1 Development Models
The use of development models with a clear purpose and information content is the answer to the
challenge of reuse of components for different car lines. Each model focuses on a certain type of
information. The full picture of the system consists of these individual models and the mappings
between them.
When developing a new car only those models affected by the differences between the previous
versionandthenewvehiclehavetobeadaptedwhiletheothermodelsremainunchanged.Tobe
more specific, the reuse of system parts calls for the separation of the architectural and the functional
