Smart piezoelectric fabric and its application to control of humanoid robot

ABSTRACT

We have developed a piezoelectric fabric for sensing applied stress and strain using piezoelectric poly-l-lactic acid (PLLA) fibers, and tailored smart clothing having the function of sensing complex human motion using the piezoelectric PLLA fabric. To provide a high-quality PLLA fabric with large piezoelectricity, simultaneously satisfying the characteristics of softness, stretchability, and wearability, we first attempted the to improve the balance of the physical properties of PLLA fibers. We investigated the use of an acrylic copolymer as a plastic additive for improving the piezoelectric and mechanical properties of PLLA fibers, since the acrylic copolymer has extremely high dispersibility and compatibility, and the optimized furthermore the PLLA fiber fabrication conditions to improve the physical properties. To realize a piezoelectric fabric with the ability of sensing complex human motion, plain, twill, and satin weaves with improved the piezoelectricity, softness, stretchability, and wearability were produced using the PLLA fibers by Teijin Limited, Japan, a joint research company. Moreover, we developed a prototype system that allows human movement, detected through the motion sensing of smart clothing obtained by sewing together pieces of piezoelectric fabric, to be linked with that of a humanoid robot. At present, simple procedures such as bending of the arms and twisting of the wrists can be replicated by the humanoid robot but not complex movements of the arms.

KEYWORDS:

• Piezoelectric polymer
• fiber
• chiral polymer
• poly-l-lactic acid
• sensor
• fabric

Acknowledgments

We would like to thank Teijin Co., Ltd., for kindly preparing the piezoelectric PLLA fabrics and smart clothing. This work was also supported in part by Grants-in-Aid for Scientific Research (Nos. 24655108 and 15K13714) from the Ministry of Education, Culture, Sports, Science and Technology of Japan. We express our deep gratitude for receiving the prize for Science and Technology in the Commendation for Science and Technology (2016) by the Minister of Education, Culture, Sports, Science and Technology.