Modelling a box with friction to the "ground"

[Sietse Achterop]

Hello forum,
coming from robotics and using gazebo/ros, I have the following question.
I want to model a person in a (rowing)boat. This to learn about forces in rowing using different riggings.
To keep things realistic I want to model the boat simply as a box that rests on the ground and has some friction.
Also the blade is a box that can be put on the ground and should have a large friction.
The rower sits on a box that can slide on the boat.
In ros/gazebo this works remarkably well.

But how can I create a box which such properties. There is ContactSphere, but no "ContactBox" I can find.
How could I solve this in Opensim?
Thanks in advance,
Sietse

[Thomas Uchida]

It looks like there are a lot of modelling decisions to make here. Regarding your specific question, there are several ways you could model the translation of the person relative to the boat. For example, if you are not interested in modelling the details of the interaction between the person and the box, you could rigidly fix ("weld") the pelvis to the box and attach the box to the boat with a prismatic joint. If you require a compliant interaction between the person and the box, you could add a ContactHalfSpace (https://simtk.org/api_docs/opensim/api_ ... Space.html) to the box and a ContactMesh or one or more ContactSpheres to the human model. The most appropriate model will depend on your specific research question.

[Sietse Achterop]

Thanks for the response!
Earlier I created a model in gazebo/ros where the pelvis was welded to the seat using a prismatic joint like you suggested,
see the attached image.
Because of instabilities in the simulation and because the human can be better modelled in opensim I made the switch.
We now also have a project with our (Groningen, the Netherlands) university human movement sciences department, where they use Opensim.

My question was about creating a box to model the boat. I couldn't find a box, but I now use a <Brick> to create it.
I use it to model the floor (rowing course) and the boat.
My current problem is how to model friction between the floor and the box.

Still having some difficulties to finding/reading the documentation, but I am getting there.
The goal of this project is to model the rowing proces including the person, the rigging and the oars, but not
the hydrodynamics. Hopefully creating a useful tool to optimize the rowing movement and the rigging, given a certain athlete.

Thanks again, Sietse