Development of a user-friendly and open-source multibody framework with the help of symbolic tools

The present work deals with an open-source library, EasyDyn, developed for teaching the fundamentals of multibody system dynamics. Using EasyDyn requires some understanding
from the user but tries to avoid the tedious parts of programming. Inwards, Easydyn is a set of C++ routines implemented to automatically build and integrate the equations of motion of a given mechanism from two user-written routines, describing on one hand the kinematics, viz. the position, velocity and accelerations according to a minimal coordinates approach and on the other hand the applied forces. A symbolic tool called CAGeM (Computer Aided Generation of Motion) is able to generate a basic C++ program directly compilable against the EasyDyn library. More particularly, the velocities and accelerations are squeezed out by symbolic differentiation from the only body positions, expressed through the formalism of homogeneous transformation matrices. Originally, CAGeM was a MuPAD script but has been recently ported to the opensource XCAS/Giac environment.
We should notice that Easydyn is available for free and runs under Unix and Windows. The code has been written with the concerns of readability and compacity and not efficiency. Beyond teach-ing purposes, EasyDyn has been well approved for the study of some complex systems such as in robotics, vehicle dynamics and biomechanics.