VDMS Tour: VDMS PROGRAM ARCHITECTURE
VDMS is programmed in Simulink but run through the MATLAB Command Window.
Knowledge of Simulink is not required (unless the user wishes to modify the
model itself). A basic knowledge of MATLAB is required.
Below is the top level Simulink block diagram. This shows the general layout of
the VDMS simulation. Each box (block) is a subsystem containing another set of
blocks--possibly more subsystems. VDMS contains over 100 subsystems. Blocks,
subsystems and signals are labeled and units are often provided.
VDMS Top Level Simulink Block Diagram
All blocks and signals are accessible to the user with the following exceptions.
First, the Core Equations of Motion block contains several compiled
S-Functions. These are compiled versions of the source code shared with MMM,
LTS and VDS (and developed over the last 30+ years). MRA's Nondimensional Tire
Model is also compiled as an S-Function and the source code is not accessible
by the user.
This type of architecture offers distinct advantages:
Compiled code runs faster than regular Simulink blocks
Compiled code avoids unintentional modification of key equations
Compiled code is mostly physics and mathematics that describe the way our world
works--there should be no reason for the user to need to alter it.
The rest of the code is OPEN TO THE USER
Users can add-in proprietary blocks representing vehicle systems, active
systems, control algorithms, etc.
Subsystems are easily substituted when a new model of a particular item is
Program flow and execution are easy to determine and understand
VDMS uses multirate, fixed-stepsize integration. The wheel spin degrees of
freedom are integrated at a faster rate than the other degrees of freedom to
improve simulation accuracy. The integration rates are user-defined.
Solution time for a simulation is roughly 1 second of computer time for every
second of simulation time. Past versions of VDMS have been compiled for
real-time and hardware-in-the-loop applications.
<< Previous | Next >>
VDMS Home | Input |
Program Architecture | Tire Model |