Sparse bins allow methods that avoid contact with other obstacles to be successful.
In APC 2015, once an object was grasped (whether by suction or by fingers), it could be directly extracted.
However, more tightly-packed bins may require brushing obstacles aside in order to reach and retrieve the
target object, as well as sliding the object along the bottom or sides of the bin.
The need to manipulate in contact may radically change both the software and hardware methods
used in the APC (e.g., shifting the emphasis toward compliant control and compliant hardware),
and the level of sensing required at the point of the manipulation (e.g., tactile and in hand vision sensors).
A key challenge to overcome in tightly packed bins is to perform the necessary manipulation under limited sensing and poor prior knowledge of the environment