Introduction to collision groups

You can split an existing collision group within a kinematic chain into multiple collision groups that can be collision checked against one another.

The kinematic chain is the section in an .mtd file that contains the information that defines the behaviour of the axis-components (the moving parts) of a machine tool or, in this case, a robot.

Often, the axis-components of a machine tool are grouped in one collision group. This means for the following robot , with its axis-components in one collision group , PowerMill does not recognise this orientation of the robot (like many other orientations) as a collision .

By splitting the collision group into multiple collision groups, you can collision check axis-components against one another. With the collision group split into multiple collision groups , PowerMill now recognises the same orientation of the robot as a collision .

Note: The single collision group is split into four collision groups, as the components in each group have the potential to collide with the components in the other collision groups. It is not necessary to split B and C nor D and E into smaller groups, as B cannot collide with C and D cannot collide with E. Also, it is best practise to create as few collision groups as possible, as each collision group increases the time PowerMill takes to collision check.

Note: PowerMill does not collision check adjacent axis-components, as PowerMill often registers a collision between two adjacent axis-components due to inaccurate modelling of the joint between them, which is, in reality, safe. The adjacent rule also applies to axis-components that are adjacent but are in different collision groups.

PowerMill collision checks these axis-components:

• A against C, D, E, and F.
• B against D, E, and F.
• C against A, E, and F.
• D against A, B, F.
• E against A, B, and C.
• F against A, B, C, and D.

For more information, see Splitting a collision group.