STP file in SimMechanics

I have some questions regarding SimMechanics, especially in its handling of STL and STP files. Because, our ultimate goal is to build real-time simulation of vehicle system, we are very keen on the simulation efficiency difference between these two file formats.

Apparently, STP file is significantly larger (5~6 times) than STL file of a same component, which is understandable since STP has all the solid information. But we don’t understand the implication on the simulation speed by these file size difference. So, first question is whether you have existing benchmark on these two file format regarding simulation efficiency?

Second question is regarding the detailed mass property handling in STP file. For a component, does SimScape re-calculate its moment of inertia very time step through integration, or just apply a coordinate transfer?

Third question, In case we will go with STL file and would like to get the mass property from STP file, how can we extract information like moment of inertial out of the STP file.

Answer 1

[Steve Miller]

> Benchmark on these two file format (STP, STL) regarding simulation efficiency?

There is no difference in the simulation execution for these two file formats. The calculation of the mass and inertia happens before simulation begins. STEP files tend to be more detailed so rendering the animation can take longer, but since that is typically handled in a separate processor thread it doesn't normally slow down the simulation speed.

> Does SimScape re-calculate its moment of inertia very time step through integration, or just apply a coordinate transfer?

No, the masses and inertias are calculated at the start of simulation.

> How can we extract information like moment of inertial out of the STP file.

You can usually get it from the CAD system. If you use Simscape Multibody Link, the masses and inertias are exported automatically. If you export STEP files, you can get the calculation of the mass and inertia from the Simscape Multibody Solid block (see Solid Simscape Multibody Solid Block Documentation), section "Derived Properties".

--Steve

[Jithinraj N]

how to get the Inertia tensor values from a mechanical assembly in simulink. So that values can be used in eulers equation of motion to find the euler angles.