IEEE Robotics & Automation Magazine - June 2013 - 89

As illustrated in Figure 11, the reactivity of the sensor, in agreement
with the optical measurements, is
defined when the first recovery
deformation occurs (interval of the
time between states C and D).

1 cm

PVC

Tapered Profile
Application: A Brief
Embedded in GNM
Introduction to Tactile Sensing
2 cm
for Robot Systems Architecture
(a)
The proposed sensor can be easily
implemented in robotic tactile systems. By using small laser diode
sources and small photodiode
detectors, the pressure sensor
requires small spaces and assures
very fast detection responses. A
possible schematic representation is
illustrated in Figure 12, where an
(b)
(c)
array of sensors indicates the fingers of a robotic hand. The sensor
Photo
Applied
can be coupled to a little laser diode
Detector
Pressure
Weight P
source by means of a coupler or
Sensor
fiber bundle. The signals coming
Light Source
Electronic
Electronic
from each sensitive sensor can be
(Broad
Lamp)
Circuit
Analyzer
detected by photodiode detectors
and can be processed by a logic network, providing by a controlled
Coaxial Cables
Optical Fiber
feedback system, commands about
the possible movements of the sen(d)
sors. The first prototype of the tactile finger robotic sensor is shown
13. (a) Design of robotic finger by GNM. (b) and (c) Images of the light coupled
in Figure 13. In this prototype, a Figure
inside the GNM: the light is emitted from the tapered profile and propagates inside the
tapered fiber [see Figure 13(a)] GNM (the light losses will increase as the pressure is applied to the finger). (d) A schematic
passes inside a polyvinyl chloride diagram of the experimental setup suitable for robotic finger implementation.
(PVC) support representing the
shape of a finger. To improve
mechanical stability, the tapered profile is glued to the of pressure forces. In particular, we proposed a highsensiPVC support by means of Thorlabs epoxy glue for fiber tivity sensor that allows the measuring of pressure forces
optic connectors. The high sensitivity of pressure detec- corresponding to weights of 5 g and can be easily impletion is performed by embedding all the PVC support in mented in tactile robotic
GNM. Figure 13(b) and (c) show the reported images of systems including shape
the robotic finger prototype. A possible experimental and dielectric permittivThe sensor is designed and
setup scheme for electrical measurements suitable for ity sensing. According to
robotic systems and signal processing is illustrated in Fig- robotic systems, the
optimized by means of
ure 13(d), where a broad lamp is connected with the mechanical control systapered fiber sensor, which transmits the signal to a pho- tem, the signal processexperimental optical and
todetector that has the ability to convert the optical signal ing, and the analysis of
into an electrical one.
some important aspects
preliminary mechanical
such as sheer force detecConclusions
tion, angle of incidence,
characterizations.
In this article, we presented a new concept of an optical tac- sensitivity, electronics,
tile sensor based on PDMS-GNM. The sensor is designed and signal saturation repand optimized by means of experimental optical and pre- resent the final goal of our work. The implementation of
liminary mechanical characterizations. For mechanical sta- the proposed robotic system, including the shape detection
bility, the proposed technology is suitable for a wide range algorithm, is also in progress.
june 2013

IEEE ROBOTICS & AUTOMATION MAGAZINE

Table of Contents for the Digital Edition of IEEE Robotics & Automation Magazine - June 2013