Page 154 - Mechatronic Systems Modelling and Simulation with HDLs

7.3 DEMONSTRATOR 2: INTERNAL COMBUSTION ENGINE WITH DRIVE TRAIN 143

do not proceed further. Such a debugger has been implemented and used. It can
represent the underlying software both on assembler and high-level language level.
The user interface of the debugger is shown in Figure 5.7.
The models were formulated in the analogue hardware description language
MAST and simulated using the Saber electronics simulator. On a SUN Sparc 20
workstation the simulation requires 22 CPU seconds. This includes the simulated
processing of 3.8 million machine instructions of the embedded processor.

7.3 Demonstrator 2: Internal Combustion
Engine with Drive Train

7.3.1 System description

This example relates to the modelling of the propulsion of a motor vehicle see also
[332]. If all components that are relevant in this context are to be considered, then
the modelling would extend from the accelerator pedal, via the actual engine and
the drive train, to the road, which has a certain gradient. If we impose narrower
limits on the model, then we can at best investigate specific parts of the system.
In what follows, the overall system will be investigated, whereby the necessary
foundations can be found for example in Roduner and Geering [349], Hockel
[146], Tiller et al. [400] or in the publication by Bosch [39], [40]. As in the
previous example, generic models are used where possible, which can be adapted
to the application case in question by suitable parameterisation. Again, the model
is based upon the assembly of the overall model from basic components.
The system under investigation is shown in Figure 7.5. The partitioning of the
system for the modelling mainly follows the function blocks shown in the illustra-
tion. At the top level, the system model consists of an electronic circuit diagram.
The components of this have been modelled using an analogue hardware descrip-
tion language, and so the whole of the overall system can be simulated without
further problems. Particular mention should be made of the fact that two types of
modelling have been used here.
The drive train primarily relates to the rotational and translational movements,
whereby here a line represents the duality of torque / angular velocity or force /
velocity. Kirchhoff’s laws in particular apply here, i.e. the forces and torques at a
node and the velocities and angular velocities in a closed loop add up to zero. The
lines in question are printed in bold.
All other lines are directional. They form a network that is comparable to the
block circuit diagrams of control technology. In particular, Kirchhoff’s laws do not
apply here. The main task of this partial network is to supply the torque generation
block and the automatic gearbox with the necessary data. This includes the control
of the combustion engine.
In the system description we start with the accelerator pedal, which in our case
represents the driver’s primary input. Its angle a pe sets the kickdown mode in train