Position vector of the "Spatial Contact Force" reaction.

Hello.

I am currently employing the "Spatial Contact Force" block to model the contact reaction between two bodies. I need the position vector of the contact point between the two bodies. That is, either the global or local position vector of the instantaneous point of contact. This information seems not to be included in the block menu.

Is there any way to measure it?.

Thanks in advance.

Answer 1

[Juan Sagarduy]

Hello Camilo

This is not trivial to derive. You can have a sensor between selected points in the two bodies and then sample this when the sensed separation distance given by the block becomes very low (contact).

Then, the contact point vector consists of the vector position of one body + fraction of the sampled vector. To know exactly, you need knowledge on the mesh. This is easiest for contact between two spheres.

Good luck / Juan

[Camilo Manrique]

Hello Juan,

Thanks for answering. Yes, it is not a trivial computation. Unfortunately, I am not dealing with spheres, so an analytical estimation does not seem to be the way to go. I am hoping to get the information from the simulation. Is there any way in which I can extract data from the mesh?. There is no mention in the documentation about this.

Thanks!

[Juan Sagarduy]

Hi Camilo

There is a function called stlread that extracts the triangulation mesh from a STL file from CAD.

So, if u use STL files in Multibody, the approach i proposed might be plausible. In any case, it remains an ambitious goal.

Cheers Juan