老年人或者運動傷害者的下肢由於退化和運動傷害造成日常生活的不便。要能改善他們的生活，需要下肢輔具來進行復建治療。為了開發更人性化且穿戴便利的下肢輔具，設計上必須避免使用笨重的馬達、傳動機構等傳統機械裝置。有鑑於此，受到電刺激產生形狀和大小改變的電致動高分子(Electroactive Polymer, EAP)受到研究者的注意。
介電彈性體(Dielectric Elastomer)是EAP材料中，最具潛力的一種材料。介電彈性體致動器(Dielectric Elastomer Actuator, DEA)具有大致動力量、大應變(自由面積應變超過380%)、極佳的反應速度(釐秒的數量級)且兼具高分子典型的特性－輕、撓性、順從性和便宜。因此，相當有潛力成為驅動輔具的致動器來主動矯正關節、輔助行走。
本研究的目標是要作一項DEA來驅動踝部輔具，因此使用3M VHB4910為介電材料，製作出拮抗式的DEAs。但是根據實驗發現，致動器所能產生的線性位移對於輔具應用上有一定的的限制。有鑑於此，本研究提出一項拮抗式旋轉輸出DEAs的設計，藉由棘輪機構能夠單向地累積小位移至大位移的原理，將拮抗式的DEAs所能產生的位移規格提升。對單一側DEA施加弦波電訊號能讓整體致動器產生線性的往復式運動，透過棘輪組的轉換，可以將線性運動轉換成單向間歇式的旋轉運動。將規格較小的線性位移轉換成旋轉位移的累積。再配合致動器致動力量提升，拮抗式旋轉輸出DEAs能夠單向間歇式地舉起負荷。

The elderly and the sports injured people are inconvenient for their daily life. Respecting the issue we attempt to develop convenient, light and quiet equipment for lower limbs. Avoid the application of motor, transmission and traditional mechanism. Researcher of the field pay attention to the EPA (electroavtive polymer) could change shape and size by the simulation of electricity.
DEA (Dielectric Elastomer Actuator) is one of the most potential materials in EPA, which can generate large actuation force (>1N), stretch (up to 380% in area) and fast response (<100ms). Besides, DEA also keep the characters of polymer –light, compliant, flexible and cheap. As to the mention above, DEA are very helpful to become the next generation of actuator for bio-mimetic robots and biomedical, etc.
The goal of this research is to create an ankle orthosis made of polymer actuator. Therefore, we use 3M VHB4910 for dielectric material to make antagonistical DEAs. But by the outcome of experiences, the linear displacement forced by the actuator in the application had its own limits. Consequently, we devise a new design-antagonistically rotational actuator according to the principle of clutch(one way displacement accumulation) to increase displacement.
Antagonistical DEAs do linear and actreciprocating motion by apply voltage (sinusoidal signal) to one side of DEAs. Linear and actreciprocating motion can be transferred to intermittentone and one way rotational motion by the set of clutch. Finally, the rotational displacement is accumulated. While improving the actuation force, antagonistically rotational actuator can lift the weight.

[1] H. Herr,and R. Kornbluh, “New horizons for orthotic and prosthetic technology: artificial muscle for ambulation,” Smart Structures and Materials 2004: Electroactive Polymer Actuators and Devices (EAPAD), Proceedings of SPIE Vol. 5385 , pp1~9.
[2] G.S. Sawicki1, K. E. Gordon2, D. P. Ferris3, “Powered Lower Limb Orthosis：Applications in Motor Adaptation and Rehabilitation,” Proceedings of the 2005 IEEE 9th International Conference on Rehabilitation Robotics, June 28 - July 1, 2005, Chicago, IL, USA, P206~211.
[3] Y. Bar-Cohen, “Electroactive Polymers as Artificial Muscles – Reality and Challenges,” Proceedings of the 42nd AIAA Structures, Structural Dynamics, and Materials Conference (SDM), Gossamer Spacecraft Forum(GSF), held in Seattle WA, April 16-19 2001, pp1~10.
[4] X. Zhang, C. Lowe, M. Wissler, B. Jahne and G.Kovacs, “Dielectric Elastomers in Actuator Technology,” Advanced Engineering Materials 7. NO 5 2005 P361~367
[5] R. Pelrine, R. Kornbluh, and G. Kofod, “ High-Strain Actuator Materials Based on Dielectric Elastomers,” Adv. Mater. 2000, 12, No. 16, August 16, pp1223~1225
[6]. N. Bonwit, J. Heim, M. Rosenthal, C. Duncheon*, andA. Beavers,”Design of Commercial Applications of EPAM Technology,” Smart Structures and Materials 2006: Electroactive Polymer Actuators and Devices (EAPAD), Proceedings of SPIE Vol. 6168, 616805..
[7] M. Rosenthal, N. Bonwit, C. Duncheon, and J. Heim, ”Applications of Dielectric Elastomer EPAM Sensors,” Smart Structures and Materials 2006: Electroactive Polymer Actuators and Devices (EAPAD), Proceedings of SPIE Vol. 6524, 65241F.
[8] J. Plante, L. M. Devita, S.Dubowsky, “A Road to Practical Dielectric Elastomer Actuators Based Robotics and Mechatronics: Discrete Actuation,” Smart Structures and Materials 2007: Electroactive Polymer Actuators and Devices (EAPAD), Proceedings of SPIE Vol. 6524, 652406.
[9] Y.Y. Jhong, C.M. Huang, C.C. Hsieh, and C.C Fu,“ Improvement of viscoelastic effects of dielectric elastomer actuator and its application for valve devices,” ”Smart Structures and Materials 2007: Electroactive Polymer Actuators and Devices (EAPAD), Proceedings of SPIE Vol. 6524, 65241Y.
[10] H. R. Choi, K. M. Jung, J. W. Kwak, and S. W. LeeaMultiple ,”degree-of-freedom digital soft actuator for robotic applications,” Structures and Materials 2003: Electroactive Polymer Actuators and Devices (EAPAD), Proceedings of SPIE Vol. 5051 , pp262-271.
[11] Qibing Pei, Marcus Rosenthal, Scott Stanford, Harsha Prahlad, Ron Pelrine,”Multiple-Degrees-of-Freedom Electroelastomer Roll Actuators,”Smart Materials and Structures, 13, N86-N92 (2004).