|"Design of an Optical Soft Sensor for Measuring Fingertip Force and Contact Recognition"
Haedo Cho, Hyosang Lee, Yeongjin Kim, and Jung Kim
International Journal of Control, Automation, and Systems, vol. 15, no. 1, pp.16-24, 2017
Abstract : "Among the various ways to estimate user intention in hand exoskeletons, a contact force measurement is
definitely the most straightforward and intuitive method. A force sensor, located at the center of a fingertip usually,
hinders the tactile sensation of the user by blocking the contact between an object and the fingertip. To overcome
this problem, a soft force sensor with horse shoe shape is utilized to measure the contact force and provide the
tactile sensation to the user. This work presents the mechanical design, implementation and evaluation of a soft
fingertip force sensor. To maximize tactile sensation of the user, we adopted a horse shoe shape structure to leave
the finger pad exposed. An optical sensing mechanism was selected for its relatively fast response compared to
other soft sensors. The whole sensor system has a soft exterior providing flexibility and a user-friendly interface.
To evaluate the sensor’s performance, we carried out sensor optimization process and calibration experiment with a
customized test bed. Then, we investigated both static and dynamic response and observed the mechanical behavior
and light intensity changes caused by the cross sectional shape and base/agent ratio of PDMS. Lastly, we applied
the proposed sensor to the glove type fingertip force monitoring system. The sensor estimates the index finger tip
force with high accuracy (R2 = 0:96) within 5N range."
Flexible sensor, force sensor, hand exoskeleton, open finger pad structure, optical sensor.
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