MATLAB: How to add inertia to a SimScape circuit that is interfaced with SimMechanics blocks in SimScape 2.1 (R2008a)

Question

The documentation for Revolute-Rotational Interface block says not to use inertia element in a SimScape circuit that is interfaced with Simulink and instead add a body in the SimMechanics side. However my design leads to a singularity without an inertia in the SimScape circuit.

Answer 1

This is due to a limitation in interfacing SimScape and SimMechanics. In the attached model the SimDriveline circuit should ideally "see" the inertia of the SimMechanics body. But in practice the solver complains about a singularity and recommends inertia added to the SimDriveline circuit.

This is done by adding dampers between the Revolute-Rotational Interface and the mechanical reference. This is a workaround for the configuration limitation of adding inertia mentioned in the documentation of Revolute-Rotational interface block.