We present the design of an active two-phase finger for mechanically mediated dexterous manipulation. The finger enables re-orientation of a grasped object by using a pneumatic braking mechanism to transition between free-rotating and fixed (i.e., braked) phases.

Our design allows controlled high-bandwidth (5 Hz) phase transitions independent of the grasping force for manipulation of a variety of objects. Moreover, its thin profile (1 cm) facilitates picking and placing in clutter. Finally, the design features a sensor for measuring fingertip rotation to support feedback control.

We experimentally characterize the finger's load handling capacity in the brake phase and rotational resistance in the free phase. We also demonstrate several pick-and-place manipulations common to industrial and laboratory automation settings that are simplified by our design.