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GENSYS in short


In Sweden modeling of railway vehicles in computers started 1971 at ASEA AB in Västerås. The development started with a linear program in the frequency domain. The very first program was named LSTAB which comprised a bogie with two wheelsets.

However it was soon realized that a linear program was not satisfactory for railway vehicle dynamics. Therefore already in 1973 the development of a non-linear time-domain simulation program began. In the new program a whole railway vehicle could be modeled. The program was named SIMFO and was a code with specific-generic-structure. The program consisted of the following two parts: SIMFO-L taking lateral-, roll- and yaw- motions into account and SIMFO-V taking longitudinal-, vertical- and pitch- motions into account. These two programs were used in the design of the high speed train X2000, built by ASEA, later ADtranz and now belonging to Bombardier Transportation.

The first official presentation of SIMFO was made by Evert Andersson in Graz 1977. The name of the presentation was "Simulation von Spurkräften und Laufeigenschaften", ZEV-Glasers Annalen 101 (1977) Nr 8/9, p.339-347.

In 1992 began the development of a three-dimensional general multi-body-dynamic program, and it was given the name GENSYS. At the same time the development of the software package moved into a new company named AB DEsolver, which has the sole task of developing and supporting the package. Since ADtranz (now Bombardier Transportation) wanted to focus on building railway vehicles.

The main calculation programs

The main calculation programs in GENSYS are:
QUASI quasistatical analysis
MODAL modal analysis
FRESP frequency-response analysis
TSIM time-domain integration

All the four major calculation programs are very general in their basic design, and with the GENSYS input data syntax it is easy to create models of mechatronic systems. If the mechatronic electronic system already is written in a m-file for Matlab or Octave it is possible to make a co-simulation with the cosim_server-command.

The coupling between wheel and rail can be modeled in many ways, see analyse_wheel-rail_coupling


To simplify the generation of input data, the GENSYS package consists of the following preprocessors:

TRACK Generation of track irregularity files
KPF Generation of wheel-rail geometrical properties
MISC Miscellaneous programs
NPICK Adding flexible modes to rigid bodies
OPTI Runs sequences of calculations


GENSYS includes three powerful postprocessors GLPLOT, GPLOT and MPLOT.

Program GPLOT is a 3-D visualisation and animation program. GPLOT can also animate the wheel/rail-contact conditions.

Program GLPLOT is similar to GPLOT but is written in OpenGL to give a nicer appearance. The model is shown in perspective and all masses are made of solid and/or transparent surfaces. Light sources and their positions that sheds light on the model can be choosen by the user.

Program MPLOT is used for postprocessing and plotting of the results. Plotting can be 2- or 3-dimensional, consisting of curves and/or scalars. Postprocessing in MPLOT consists of: algebraic operations, filtering operations, Fourier transform operations, different ride comfort assessments and different statistical evaluation methods.
MPLOT can handle data from several MPdat-files simultaneously.

Validation and development

The program package has for different kinds of railway vehicles continuously been validated by ASEA, later Adtranz and today Bombardier Transportation. Validation of the program package has also been carried out for the following benchmarks:

The development of GENSYS is carried out by AB DEsolver in cooperation with the Royal Institute of Technology (KTH) Stockholm and Chalmers University of Technology Gothenburg Sweden.


GENSYS is available from AB DEsolver under a license agreement. The annual license fee includes: telephone and e-mail support, introduction course, maintenance and updates.


The following document shows a couple of examples how GENSYS can be used:

Workshop on Rail Vehicle Dynamics
12-14 April 2011
Faculty of Mechanical Engineering Kraljevo
International Association for Vehicle System Dynamics-IAVSD