I have found several sources that state that a Joint space trajectory model is not capable of dealing with obstacles in the manipulator workspace. These sources include:
slide 10 of "Manipulator Trajectory Planning":
and also Mathworks in their presentation on Trajectory Planning for Robot Manipulators on Youtube at timestamp 3:16.
The problem I am facing is that these sources do not explain why joint space models can not deal with obstacles.
Is there somebody here that can shed some light on this?