Fixed constraint on cable nodes

[Fokion-Sanoudos]

I am trying to use the cable constraint of SoftRobots as beam in order to push a surface. The problem is that when I try to extend the beam the node of the beam moves and rotates instead of being fixed. I don't want to use a pull point because I want to the whole structure to move but I was wondering if fixed rotation or general constraints can be added to the cable node.

Edit: I have uploaded a zip file with the simulation files.
Simulation.zip

[EulalieCoevoet]

There is a component in SOFA called PartialFixedConstraint that you can use in addition to the CableConstraint to do that I think.
With this component you can constrain some points of your model to be fixed in chosen directions.
I don't think adding this component to the cable node will work though, you should probably add it directly to the "surface" node.

[EulalieCoevoet]

I imagine your code looking something like that:

surface = rootnode.addChild('Surface')
surface.addObject('YOUR_SOLVERS_MESHLOADER_TOPOLOGY')
surface.addObject('MechanicalObject')
# You can use an engine to select the indices of your model to be partially fixed (BoxROI for instance)
surface.addObject('YOUR_ROI_ENGINE', name='roi')  
# Use this component to fix the selected points in all directions except x for instance
surface.addObject('PartialFixedConstraint', indices='@roi.indices', fixedDirections=[0,1,1])  
surface.addObject('YOUR_MASS_AND_FORCEFIELD')

# You can either directly pull/push a point of your FEM mesh that as been partially fixed
cable.addObject('CableConstraint', indices=[YOUR_INDEX])

# OR pull/push a point that is located inside an FEM element (tetrahedron I guess) that has been partially fixed 
# and use a mapping
cable = surface.addChild('Cable') 
cable.addObject('MechanicalObject', position=[YOUR_POSITION])
cable.addObject('CableConstraint', indices=[0])
cable.addObject('BarycentricMapping')

[EulalieCoevoet]

@Fokion-Sanoudos does it work with this idea?

[Fokion-Sanoudos]

I have already been doing that with my code. It kinda works but I was looking to constraint the rotation or generally constraint somehow the movement of the "pull point" of the cable. A solution I found is that I constrained the rest of the body in one direction to stop the rotations. It is not ideal but it will have to do.

[EulalieCoevoet]

Hi @Fokion-Sanoudos, could you write a comment with your final solution and mark it as the answer?

[Fokion-Sanoudos]

It's really not the answer to the question it is just a workaround that I implemented.

[Fokion-Sanoudos]

This is what I did at the end:
ring.addObject('BoxROI', name='roic', box=[15, 81/2, -420/2, -15, -81/2, 420/2], drawBoxes=True) ring.addObject('PartialFixedConstraint', fixedDirections= [1, 1, 0],indices=ring.roic.indices.getLinkPath())