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models of the driver and the assistance system developed in the project and
components for monitoring and recording. The most convenient way to cope
with continuing changes of these modules is to refrain from a deep integration
into one system and rather combine them via a co-simulation environment.
For that purpose, we use a commercial implementation of the IEEE standard
1516 [3] for coupling simulators (HLA, “High Level Architecture”). This stan-
dard defines how a joint run of different component simulators is orchestrated
by a central component (RTI, “Run-Time Infrastructure”).
The HLA term for a set of combined simulators is
federation
,andeach
partner is called a
federate
. HLA offers a time management service which
enables to synchronize federates running at different and even variable step
resolutions. A federate is
time regulating
if it influences the advance of other
federates, and it is
time constrained
if its own evolution is restricted by others.
Time management permits to keep the data exchange in accordance with
the progress of logical time, opposed to best-effort simulation where data
are consumed as they become available during simulation. To limit variation
between different simulation runs with the same parameters, i.e., to achieve a
high degree of reproducibility, we used this time management. For technical
reasons, in particular the nature of the commercial trac simulation software,
even this does not suce for full reproducibility. It is, though, planned to
replace that component with another one what we expect to remove these
problems.
Fig. 1. Architecture of the federated simulation.
Fig. 2 depicts the structure of the main components and their integration
by the RTI. In particular, the main components are models of the driver and
assistance-system (Advanced Driver Assistance System, ADAS) on the left of
the figure and a simulation of the ego car, which is the car controlled by the
driver model, and the trac environment on the right. Further components
