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 electrical-engineering area, it has been also called terminal, compartmental or multipole approach. Later, some software-engineering oriented people started to call it the object-oriented 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 mixed-signal hardware description simulation language MAST, a predecessor of the IEEE standard 1076.1, or VHDL-AMS. Academic users complain about the enormous cost and a steep learning curve of this industry-oriented 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 algebro-differential 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 web-based 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 differential-algebraic system of equations symbolically to state-space form if possible. Graph-theoretical 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.

Bond-graph approach

20-sim - CLP, University of Twente
20-sim uses modeling through iconic diagrams, block diagrams, bond graphs and equations. Fully observable, unlimited hierarchical model structure. Active support of top-down, inside-out and bottom-up modeling. Open component model libraries. Support of vectors and matrices, as well as multi-dimensional bonds and signals. Export of data and models to Matlab. Built-in runtime compiler. Parameter Optimization, ANSI-C 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)

Block-diagram approach

Simulink - MathWorks, Natick, MA
Simulink provides an interactive, block-diagram simulation environment. It includes a library of linear, nonlinear, continuous-time, discrete-time, 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 object-oriented 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 real-time 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 user-defined FORTRAN or C. Virtual prototypes of entire systems can be constructed via links to other CAE software. Source code is automatically generated to support real-time simulation.

VisSim - Visual Solutions, Westford, MA
VisSim executes MATLAB commands, functions and .m files. An extension of the MS C/C++ compiler for integrating user-developed programs into custom blocks. Create alphanumeric text strings that VisSim displays upon the occurrence of a conditional event. Real-time 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, arbitrary-precision numerics, both two-dimensional and three-dimensional 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

VHDL-AMS Parser

VHDL tools and models

SPICE to VHDL-AMS translator