EasyDyn, Easy Simulation of Dynamic Problems

EasyDyn is a C++ library for the simulation of problems represented by second-order (or first-order) differential equations and, more particularly, multibody systems.

The library is free and distributed under the GPL. To have some more information, please, have a look at the user guide or this paper

The library is organized in 4 modules

vec: C++ classes relative to vector calculus (vector, rotation tensor, homogeneous transformation matrix, inertia tensor) + assignment methods and operators
sim: routines for integration of second-order differential equations;
mbs: front-end to sim building the equations of motion from kinematics and applied efforts;
visu: easy creation of files describing scenes composed of moving 3D objects for further visualization.

Moreover, it provides a utility, called CAGeM (Computer-Aided Generation of Motion), which automatically generates the kinematics of a multibody system only from the position matrices. CAGeM is actually a MuPAD script, which uses the symbolic features of MuPAD to derive the position matrices. MuPAD is a computer algebraic system which was free for non commercial applications when EasyDyn was started. Unfortunately, it is no longer the case. We investigate but we have not found so far an open source computer algebraic system with all features of MuPAD. Wait and see.

The visualization will be performed with the help of EasyAnim that can also be downloaded from this site. You will find in the archive the necessary information to use it. Binary versions can also be downloaded directly. For immediate information, have a look at the Readme. Herebelow some screenshots of EasyAnim.

Note that EasyAnim is used as an animation tool for the multibody simulation package MBDyn developed at the Dipartimento di Ingegneria Aerospaziale of the « Politecnico di Milano ». See this page to know how EasyAnim is used and actively developed in Milano.

Download

EasyDyn-1.2.4.tgz (july 31 2008)

EasyDyn-1.2.4.zip (july 31 2008)

EasyDyn-1.2.3.tgz (november 30 2004)

EasyDyn-1.2.3.zip (november 30 2004)

EasyAnim-1.3.1.tgz (december 2006)

EasyAnim-1.3.1.zip (december 2006)

EasyAnim-1.3.tgz (january 2005)

EasyAnim-1.3.zip (january 2005)

Binary versions of EasyAnim: Linux/Motif, Linux/Athena (unstable) and Windows.

Related software

To use EasyDyn, you will need a C++ compiler, the Gnu Scientific library (GSL) and, eventually, LAPACK. All these packages are included in the popular Linux distributions.

Under Unix, you should have a C++ compiler. If not, I recommend the excellent gcc from the FSF. Please note that you need a version over gcc 3.0 due to a change in the C++ ABI.

You can also download freely the GSL and LAPACK. Note that version 1.2.4 of EasyDyn no longer needs LAPACK but needs GSL 1.10 (or above).

Under Windows, I recommend mingw, an implementation of gcc for Windows and the related environment Dev-cpp. To make your job easier, please download this precompiled version of GSL-1.11 for mingw.

Problems

EasyDyn comes along with a set of problems that can be solved by EasyDyn, but also with any MBS tool. These problems can be a good source of inspiration for all professors involved in teaching MBS dynamics. You will find below the description of all problems in English and in French. You will find not only the data to solve the problem but also some expected results. We have of course completely described solutions, which are not distributed for the simple reason that our students have to solve some of them.

Wheel on a circular path EN FR	2 wheels on a circular path EN FR	Robot EN FR	Composed pendulum EN FR
Rotating pendulum EN FR	Sliding pendulum EN FR	Airplane nose suspension EN FR	Slider crank mechanism EN FR
Truck braking EN FR	Valve EN FR	Vertical motion of a simplified vehicle EN FR	Watt regulator EN FR