problem of slow simulation for the imported CAD files of robot

MiladSh · August 14, 2018, 11:49am

Hello,
I have simulated my humanoid robot in the Choreonoid and I have exported the CAD files of my robot from solidworks file to VRML files,
There is a problem that by increasing the size of VRML file the simulation time increases drastically. I have tried a lot of methods to decrease the size of the VRML file but it was not successful.
I guess the Gazebo simulation software solve this problem by separating the visualize part of the model with the collision part, therefore we can have a complicated geometry for the visualize robot and a simple model for modeling the collision.
Would anyone help me that I use the visualization of my whole robot in Choreonoid without increasing the time of simulation?

Thanks in advance

yosuke · August 15, 2018, 6:29am

Yes, using coarse mesh for visualization and primitive shape for collision detection is effective in this case, and is possible to use in Choreonoid as well.

If you use body format (recommended), you can use Visual and Collision elements to define each shapes:

github.com

s-nakaoka/choreonoid/blob/master/share/model/PA10/PA10.body#L17


      
          -
            name: BASE
            jointType: fixed
            mass: 3.04
            centerOfMass: [ 0, 0, 0.075 ]
            inertia: [
              1, 0, 0,
              0, 1, 0,
              0, 0, 1 ]
            elements:
              Visual: { resource: { uri: "parts/BASE.wrl" } }
              Collision:
                shape:
                  rotation: [ 1, 0, 0, 90 ]
                  translation: [ 0, 0, 0.1 ]
                  geometry:
                    type: Cylinder
                    height: 0.2
                    radius: 0.115
          -
            name: J1

If you prefer VRML, it is possible by using Surface node:

github.com

s-nakaoka/choreonoid/blob/8a098d78c2ffc3b49449d377a0729b4c3cefc806/share/model/GR001/GR001.wrl#L338


      
          			     rotorResistor 1.0
          			     children[
          			       DEF R_ANKLE_R_LINK Segment{
          				 centerOfMass -0.012299329345648103 -0.011256454634381104 -0.018194268448920348 
          				 mass 0.01792 
          				 momentsOfInertia[
          				  5.102862742548993e-06 -1.4311400561157794e-08 -1.2500454265702693e-08 
          				  -1.4311400561157794e-08 1.1932351766822529e-05 -4.1556885057173572e-07 
          				  -1.2500454265702693e-08 -4.1556885057173572e-07 1.5962207274521142e-05 ]
          				 children[
          				   Surface {
          				     visual [ Inline { url "parts/R_ANKLE_R.wrl" } ]
          				     collision [
          				      Transform {
          					translation -0.0125 -0.0135 -0.0202
          					children [
          					  Shape { geometry Box { size 0.086 0.057 0.002 } }
          					]
          				      }
          				     ]
          				   }

MiladSh · September 2, 2018, 7:24am

Thank you very much for your help. I have used .wrl format and It works fine. I have attached the image of the imported humanoid robot to Choreonoid