タイトル平成27年度―平成28年度成果報告書 次世代ロボット中核技術開発/(革新的ロボット要素技術分野)次世代機能性材料/コンデンサ化マテリアル基材によるソフトアクチュエータ開発
報告書年度2015 - 2016
委託先名株式会社ブイ・アール・テクノセンター 国立大学法人岐阜大学
 上記、多層DEAの試作と並行して、シミュレーションの視点からは、多層DEAについて、いくつかの典型的な電気弾性計算を実施し、期待される性能評価を試みた。具体的には、CAEソフトウェアのANSYS R16.2を用いて、誘電体の線形静電場問題と、非圧縮性エラストマーの幾何非線形構造問題をカップリングできる要素により、薄膜化・多層化・電位差・変位量などの関係を確認するとともに、CAE計算時および作成時における問題点の洗い出しを行った。とくに、有限要素メッシュの偏平さの回避と、電界破壊強度への対策が重要なことを確認した。なお、物性値については既往の研究を参考に、比誘電率を4.5、機械的な構成則にYeoh超弾性モデルを用いた.
英文要約“Research and development of innovative robotic components and its effective manner of utilization using next generation functional materials: Development of soft actuator based on capacitor materials”
Towards practical uses of DEAs, we aimed at reducing actuation voltage, whose current typical value is several kV. Similar to capacitors, induced deformation of DEA depends on the amount of charge stored. This means that to induce large deformation with low actuation voltage, it is essential to increase capacitance. For this, we made DEAs with thin films of dielectric layers, and ones with large surface area by roughening. We found indeed the both strategy works. In addition, to compensate the decease of the deformation due to thinning of the dielectric layers, we made a prototype of multilayered DEA. Another issue to realize large deformation is to develop flexible electrodes which do not impede deformation of DEAs. For this, we searched for fillers to make elastomers conductive. And, we found that by mixing MWCNT with a dispersant, conductivity of elastomers significantly increased. From computational viewpoint of the DEA in advance, several typical numerical experiments have been performed for manufacturing physical multi-stacking DEA devices. Concretely, relations among membrane-thinning, multi-stacking, electric voltage, and mechanical displacement were verified and various problems for their CAE computing and physical manufacturing have been checked by using finite elements, which are suitable for coupling both linear electro-static problem for dielectric body and nonlinear electro-mechanical problem for elastomer. Especially, it is recognized that finite element meshes should be almost cubic and the breakage of electric field should be adequately treated. Material parameters have been chosen as 4.5 for relative permittivity and ones for Yeoh’s hyper-elastic model of mechanical constitutive law, which are based on values in a literature. We also developed evaluation methods of self-sensing control of DEA. A common problem in using sensor outputs for self-sensing actuation is contaminations of input and sensor voltages into measurement voltages. One way to avoid this problem is to measure only the sensor voltage with a bridge circuit. By making RC and CC bridge circuits by inserting a resister and a capacitor, sensor outputs proportional to strain rate and strain can be measured, respectively. Another choice would be use of current control system with a shunt resistor. We investigated various current control systems with a shunt resistor. The control method is now ready to use, once the multilayered DEA is developed and its physical parameters are identified. Finally, we made an estimate on required performances of the DEA by comparing with human muscles. We also proposed a fixture model to evaluate the DEAs. Considering devices and control methods for modularization of DEA, we designed whole actuator systems. We picked up 48 companies which may be interested in our actuators, and visited 8 companies among them. We propose to develop cooking robots with our DEA actuator, in terms of high demands and immediate impacts on the market.