  We present pneumatic shape-shifting fingers to enable a simple parallel-jaw
gripper for different manipulation modalities. By changing the finger geometry,
the gripper effectively changes the contact type between the fingers and an
object to facilitate distinct manipulation primitives. In this paper, we
demonstrate the development and application of shape-shifting fingers to
reorient and grasp cylindrical objects. The shape of the fingers changes based
on the air pressure inside them and attains two distinct geometric forms at
high and low pressure values. In our implementation, the finger shape switches
between a wedge-shaped geometry and V-shaped geometry at high and low pressure,
respectively. Using the wedge-shaped geometry, the fingers provide a point
contact on a cylindrical object to pivot it to a vertical pose under the effect
of gravity. By changing to V-shaped geometry, the fingers localize the object
in the vertical pose and securely hold it. Experimental results show that the
smooth transition between the two contact types allows a robot with a simple
gripper to reorient a cylindrical object lying horizontally on a ground and to
grasp it in a vertical pose.
