There are two distinct phases when using PRM motion planning. These are performed separately in RoboDK, which improves the efficiency of the feature. The slower "construction phase" only needs to be performed once, whilst the quicker "query phase" can be repeated many times.

The two phases are:

Construction phase (slow) — The PRM algorithm randomly places points within the robot's free workspace. It then tries to connect these points together, to form a roadmap of collision-free paths within the workspace.
Query phase (fast) — The planner tries to find the shortest collision-free path between two target points by using the roadmap created in the construction phase.

For more information about how the RoboDK PRM algorithm works, please refer to this blog post.

This section shows how to use both of these phases in a RoboDK program. An example welding setup is used to demonstrate the functionality.

Using the PRM Motion Planner