Problems about the xml file?

[GAOYUAN-robot]

Dear Dr Xu

1. As shown in this picture, How is the collision file in this code generated? such as contacts/base_link.txt，contacts/one0_link.txt，contacts/one1_link.txt ...
   

2. If I want to insert a surface into the part as shown in the picture, how can I define its collision parameters so that it can come into contact with other objects?
   

[GAOYUAN-robot]

Dear Dr Jie Xu

1. I imported the file "qumian2.obj" into the file "unstable_grasp.xml" and created an object named "box_mesh". But this object named "box_mesh" does not appear to be an entity, because the object named "load" will pass through the object named "box_mesh" and they cannot contact with each other.
   

2. I noticed that I can import the obj file into the xml file using the method shown in the picture below (adopted from a task named "dclaw_rotate"), How is the collision file in this code generated? such as contacts/base_link.txt，contacts/one0_link.txt，contacts/one1_link.txt ...( I generated .obj files from Solidworks and 3D maxs)
   

3. If I want to insert an obj file into xml file and generate an object, how can I define its collision parameters so that it can come into contact with other objects?