Fluidic Tactile Sensor
A tactile sensing apparatus includes a distal phalanx of a robotic digit and a tactile sensor attached to the distal phalanx. The tactile sensor includes a core coupled to the distal phalanx and an elastic skin coupled to the core with an inner surface of the elastic skin extending over a ventral side of the core. A cell filled with a gaseous fluid is encapsulated between the ventral side of the core and the inner surface of the elastic skin. A fluid pressure inside the cell is responsive to a contact force applied to an outer surface of the elastic skin. A pressure transducer is communicatively coupled to the cell to measure fluid pressure in the cell.
1 . A tactile sensing apparatus comprising:
a distal phalanx of a robotic digit; and
a tactile sensor attached to the distal phalanx, the tactile sensor comprising:
a core having a dorsal side and a ventral side, the core coupled to the distal phalanx at the dorsal side;
an elastic skin having an inner surface and an outer surface, the elastic skin coupled to the core with the inner surface extending over the ventral side of the core;
at least one cell encapsulated between the ventral side of the core and the inner surface of the skin, the at least one cell filled with a gaseous fluid, wherein a fluid pressure inside the at least one cell is responsive to a contact force applied to the outer surface of the elastic skin; and
a pressure transducer communicatively coupled to the at least one cell to measure the fluid pressure in the at least one cell.
2 . The tactile sensing apparatus of claim 1 , wherein the gaseous fluid is air.
3 . The tactile sensing apparatus of claim 1 , wherein the core is nonplanar.
4 . The tactile sensing apparatus of claim 3 , wherein the ventral side comprises an outwardly curved surface at a tip thereof.
5 . The tactile sensing apparatus of claim 1 , wherein the core comprises a channel, and wherein the pressure transducer is communicatively coupled to the cell through the channel.
6 . The tactile sensing apparatus of claim 1 , further comprising a first circuit board coupled to the core proximate the dorsal side of the core and communicatively coupled to the pressure transducer.
7 . The tactile sensing apparatus of claim 6 , further comprising a second circuit board coupled to the distal phalanx and communicatively coupled to the first circuit board.
8 . The tactile sensing apparatus of claim 7 , wherein the second circuit board and core are on opposed sides of the distal phalanx, and further comprising a cover attached to the distal phalanx and disposed over the second circuit board.
9 . The tactile sensing apparatus of claim 8 , wherein the cover extends over a portion of the elastic skin proximate a perimeter of the distal phalanx.
10 . The tactile sensing apparatus of claim 1 , wherein an edge of the elastic skin sealingly engages the core to form a sealed environment between the inner surface of the elastic skin and the ventral side of the core, and wherein the at least one cell is formed in the sealed environment.
11 . The tactile sensing apparatus of claim 1 , wherein the core is rigid such that tactile sensing is primarily a function of the fluid pressure.
12 . The tactile sensing apparatus of claim 1 , wherein the core is semi-rigid such that tactile sensing is both a function of the fluid pressure and a stiffness of the core.
13 . A tactile sensing apparatus comprising:
a distal phalanx of a robotic digit; and
a tactile sensor comprising:
a core having a dorsal side and a ventral side, the core coupled to the distal phalanx at the dorsal side;
an elastic skin having an inner surface and an outer surface, the elastic skin coupled to the core with the inner surface extending over the ventral side of the core;
a plurality of cells encapsulated at a plurality of locations between the ventral side of the core and the inner surface of the elastic skin, each cell filled with a gaseous fluid, wherein a fluid pressure inside the cell is responsive to a contact force applied to the outer surface of the elastic skin; and
a plurality of pressure transducers each communicatively coupled to one of the cells to measure the fluid pressure in the cell.
14 . The tactile sensing apparatus of claim 13 , wherein a plurality of portions of the inner surface of the elastic skin sealingly engage the ventral side of the core to form the plurality of cells at the plurality of locations.
15 . The tactile sensing apparatus of claim 13 , wherein two adjacent cells of the plurality of cells share a cell boundary formed by a portion of the elastic skin, and wherein the cell boundary transmits a pressure applied to the cell boundary from one of the two adjacent cells to the other of the two adjacent cells.
16 . The tactile sensing apparatus of claim 13 , wherein the gaseous fluid is air.
17 . The tactile sensing apparatus of claim 13 , wherein the core is nonplanar.
18 . The tactile sensing apparatus of claim 17 , wherein the ventral side comprises an outwardly curved surface at a tip thereof.
19 . The tactile sensing apparatus of claim 13 , wherein the core comprises a plurality of channels, and wherein the pressure transducers are communicatively coupled to the cells through the channels.
20 . The tactile sensing apparatus of claim 13 , further comprising:
a first circuit board coupled to the core proximate the dorsal side of the core and communicatively coupled to the pressure transducers; and
a second circuit board coupled to the distal phalanx and communicatively coupled to the first circuit board.