Special Issue: Soft Robotics

International Journal of Control, Automation and Systems 2017; 15(1): 16-24

Published online January 19, 2017

https://doi.org/10.1007/s12555-016-0470-3

© The International Journal of Control, Automation, and Systems

Design of an Optical Soft Sensor for Measuring Fingertip Force and Contact Recognition

Haedo Cho, Hyosang Lee, Yeongjin Kim, and Jung Kim

KAIST

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.

Keywords Flexible sensor, force sensor, hand exoskeleton, open finger pad structure, optical sensor.

Article

Special Issue: Soft Robotics

International Journal of Control, Automation and Systems 2017; 15(1): 16-24

Published online February 1, 2017 https://doi.org/10.1007/s12555-016-0470-3

Copyright © The International Journal of Control, Automation, and Systems.

Design of an Optical Soft Sensor for Measuring Fingertip Force and Contact Recognition

Haedo Cho, Hyosang Lee, Yeongjin Kim, and Jung Kim

KAIST

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.

Keywords: Flexible sensor, force sensor, hand exoskeleton, open finger pad structure, optical sensor.

IJCAS
May 2024

Vol. 22, No. 5, pp. 1461~1759

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