  High resolution tactile sensors are often bulky and have shape profiles that
make them awkward for use in manipulation. This becomes important when using
such sensors as fingertips for dexterous multi-fingered hands, where boxy or
planar fingertips limit the available set of smooth manipulation strategies.
High resolution optical based sensors such as GelSight have until now been
constrained to relatively flat geometries due to constraints on illumination
geometry.Here, we show how to construct a rounded fingertip that utilizes a
form of light piping for directional illumination. Our sensors can replace the
standard rounded fingertips of the Allegro hand.They can capture high
resolution maps of the contact surfaces,and can be used to support various
dexterous manipulation tasks.
