Multibody Simulation using sympy, scipy and vpython

The talk is about the implementation of multibody simulation in the scientific python world on the way to a stage usefull for engineering and educational purposes. Multibody simulation (MBS) requires two major steps: first the formulation of the specific mechanical problem. Second step is the integration of the resulting equations. For the first step we use the package sympy which is on a very advanced level to perform symbolic calculation and which supports already Lagrange’s and Kane’s formalism. The extensions we made are such that a complex mechanical setup can be formulated easily with several lines of python code. The functionality is analogous to well known MBS-tools, with that you can assemble bodies, joints, forces and constraints. Also external forces even in a cosimulation model can be added on top. The second step, the integration is done via ode-integrators implemented in scipy. Finally for visual validation the results are visualized with the vpython package and for further analytics with matplotlib.

Conclusion: not only highly constrained pendulums with many rods and springs but also driving simulation of passenger cars an be performed with our new extension using python packages off the shelf.