
Software for Multidisciplinary System
Simulation
Isomorphic approach
Software based on this approach allows for submitting dynamic models of real systems in a form
the topology of which is similar to the topology of the modelled real systems.
Thus the models can be set up based on mere inspection of the real system configuration
without forming any eqautions, block diagrams, of bond graphs. The underlying equations are formed
automatically based on constitutive relations of the system components component and on the
physical laws governing the component interactions. As this approach was first developed in
the electricalengineering area, it has been also called terminal, compartmental or
multipole approach. Later, some softwareengineering oriented people started to call it the
objectoriented approach.
Saber
 Introduced by Analogy, Beaverton OR, in 1987
This is definitly the most advanced software in the field of multidisciplinary modeling and simulation.
First developed for powerful workstations, later became available also for PC computers. Saber uses the
mixedsignal hardware description simulation language MAST, a predecessor of the IEEE standard 1076.1,
or VHDLAMS. Academic users complain about the enormous cost and a steep learning curve of this
industryoriented software.
Dynast  DYN, Prague
A predecessor of Dynast, developed at the end of seventies at the Czech Technical University in Prague,
admits system models characterized
by a set of algebrodifferential equations, by a block diagram, by
a physical model in the form of a multipole diagram or by a combination
of the above approaches. The multipole diagrams allow for portraying the
actual physical structure of the modeled real systems without deriving
any equations or constructing any graphs. Block and multipole diagrams
can be submitted to DYNAST in a graphical form using a webbased Java applet
or a more sophisticated OrCAD schematic capture editor.
Dymola  Dynasim AB, Lund
Dymola provides an object oriented modeling
using Modelica language. Dymola allows for graphical model composition
from library models, continuous/discret simulation and 3D animation.
Bond graph methodology can be used. Model details are given by ordinary
differential and algebraic equations, also in a matrix form. Dymola
converts the differentialalgebraic system of equations symbolically to
statespace form if possible. Graphtheoretical algorithms are used to
determine which variable to solve for in each equation and to find minimal
systems of equations (optionally using tearing) that have to be solved
simultaneously (algebraic loops). The equations are then, if possible,
solved symbolically. Linear systems of equations can be solved symbolically
or numerically. Dymola also supports instantaneous and discontinuous
equations.
Bondgraph approach
20sim  CLP, University of Twente
20sim uses modeling through iconic diagrams, block diagrams, bond graphs
and equations. Fully observable, unlimited hierarchical model structure.
Active support of topdown, insideout and bottomup modeling. Open component
model libraries. Support of vectors and matrices, as well as multidimensional
bonds and signals. Export of data and models to Matlab. Builtin runtime
compiler. Parameter Optimization, ANSIC Code Generation, Linearization,
Graph Animation and 3D Animation toolboxes. (demo)
HybrSim
HYBRSIM is an implementation of a hybrid
bond graph modeling and simulation. It embodies a set of physical principles
that govern discontinuous changes in physical system models which violate
the continuity of power constraint and at times instantaneous energy losses
may occur. (Java source files available)
Blockdiagram approach
Simulink  MathWorks, Natick, MA
Simulink provides an interactive, blockdiagram simulation environment.
It includes a library of
linear, nonlinear, continuoustime, discretetime, multirate, conditionally
executed, and hybrid blocks. Blocks can be grouped into hierarchies to
create a simplified view of subsystems. Simulink allows customization with
regard to incorporating user C code.
Simulink solvers support differential algebraic equations (DAEs) with
algebraic loops. The solvers also support stiff systems, systems with algebraic
loops, and systems with state events.
Simulink includes many features for linearization,
equilibrium point determination, animation, parameter optimization,
and parametric analysis.
With integration to MATLAB, Simulink offers immediate access to a
range of other analysis and design tools.
ACSL  AEgis Research
ACSL (Advanced Continuous Simulation Language) is a simulation and
modeling environment with several components. A visual programming
tool facilitates building ACSL models
in the form of objectoriented graphical block diagrams.
A mathematical analysis package provides
visualization and analysis of simulation data.
An optimizer allows for the estimation
and optimization of critical parameters in simulations.
A modeling environment generates
C code from specific portions of models.
A realtime set of software and hardware allows
to synchronize simulations to a real time clock.
A visualization package facilitates building dynamic
animations from simulations.
An open applicaiton program interface (API)
allows to build custom user interfaces to access
simulations.
Easy5  Boening Co., Seattle, WA
EASY5 software is used to model and simulate dynamic systems with continuous and digital subsystems.
Systems are quickly modeled with functional blocks and/or with predefined blocks representing system
components, as well as userdefined FORTRAN or C. Virtual
prototypes of entire systems can be constructed via links to other CAE software.
Source code is automatically generated to support realtime simulation.
VisSim  Visual Solutions, Westford, MA
VisSim executes MATLAB commands, functions and .m files.
An extension of the MS C/C++ compiler for integrating userdeveloped
programs into custom blocks. Create alphanumeric text strings that
VisSim displays upon the occurrence of a conditional event.
Realtime data interface.
Analytical approach
Maple  Waterloo Maple, Waterloo, Canada
Maple an interactive computer algebra system that provides a
mathematical environment for the manipulation of symbolic algebraic
expressions, arbitraryprecision numerics, both twodimensional and
threedimensional graphics, and programming.
Mathematica  Wolfram Research, Champaign, IL
Mathematica is an integrated computing system, combining interactive
calculation (both numeric and symbolic), visualization tools, and a
programming environment. Mathematica can perform symbolic calculations
in algebra, calculus, differential equations, and higher mathematics.
Mathematica also has a communications protocol which allows it to
communicate and share data with other programs.
It can also communicate between networked Mathematica processes.
Auxiliary software
VHDLAMS Parser
VHDL tools and models
SPICE to VHDLAMS translator
