Kazuhiro Iwata

3-D finite-element analysis of fiber-reinforced soft bending actuator for finger flexion

Towards the development of a safe, small, lightweight and human-friendly finger exoskeleton, device made from high elasticity material driven by pneumatic source; or simply known as soft actuator is currently being paid to attention. The study is to determine the optimum fiber-reinforced elastic soft actuator model to be employed in an exoskeleton for finger rehabilitation. Bending motion anticipated from a 3-D finite element actuator model is verified in the nonlinear finite element software, MARC™. The effectiveness of the proposed model is discussed based on the displacement data obtained from the large strain finite element analysis. Specific geometric properties, material properties, contact and boundary conditions related to the real experimental testing were applied to the analysis. Based on the results, the proposed model shows a good presentation of bending motion at applied pressure of 150 kPa. The behavior of bending motion which is greatly influenced by the angle of the fiber reinforced to the actuator is also discussed.

Long bending rubber mechanism combined contracting and extending tluidic actuators

This study aims at development of a multi-directional bending mechanism with thin and long body driven by fluidic rubber actuators. Generally bending mechanisms with fluidic rubber actuators can have advantages of smooth and continuous motion, however because of their low stiffness it is difficult to generate high output force. To solve this problem, we have proposed a novel bending mechanism combined with contracting and extending rubber actuators. By bundling rubber actuators with different types, the developed bending mechanism can have the high stiffness. In this report, optimized extending and contracting rubber actuators are made basis on a McKibben actuator, then they are combined to be the bending mechanism. Experimentally stiffness of the mechanism is measured and is compared with a bending mechanism bundled with same motion type actuators. Resulting high stiffness can be recognized by the proposed mechanism. Additionally, a very long bending mechanism, which is 7m in length, is developed and its motion is demonstrated.