Port-based pendulum modeling from a didactic point of view

This paper is focused on the didactic aspects of port-based modeling of simple planar mechanisms represented by bond graphs. The relation between energy-based equation derivation techniques like Lagrange's and Hamilton's methods and Newton- Euler based techniques will be explained by modeling variations on a pendulum model with an emphasis on obtaining insight and preparing for the framework of port-based modeling of spatial multibody mechanisms.. Even though final results may be equivalent, the intermediate bond graph representation of these approaches will show that some methods are superior to others, depending on the purpose and desired flexibility of the model. The approach is also motivated by the fact that many consider 'bond graph modeling' as an alternative to other modeling approaches, while the bond graph representation may be used to give a graphical interpretation of all sort of modeling approaches which facilitates their comparison, as long as they have some relation with an energy-consistent approach, which is a requirement for a sound description of physical phenomena.