[MoveIt!] How do the motion planners work concretely in MoveIt! ?

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Hello everyone,

I was looking at the planning algorithms used in MoveIt!. The OMPL library is mostly sample-based algorithms. I understand how these algorithms sort of work, but I read somewhere that these algorithms have no concept of the robot. So isn't it possible that the trajectory these algorithms generate are unfeasible for the robot (collision of a robot link with environment for example)? It's obvious that we want these trajectories to be feasible for the robot, so how is the robot eventually taken into account?

Thanks in advance