Design and Analysis of Fiber-Reinforced Soft Actuators for Wearable Hand Rehabilitation Device

Abstract

Fiber-reinforced soft actuators have great potential for the development of wearable technology. However, its complex structural design, nonlinear soft material body, fluid-driven dynamics and high manufacturing costs have brought huge challenges to system modeling, control and application. To improve this situation, a novel fiber-reinforced soft actuator is designed and analyzed. First, a wearable hand rehabilitation device based on fiber-reinforced soft actuators with three-air-chamber structure is designed. Next, using Yeoh model and principle of virtual work, we establish a bending mathematical model of the soft actuator, whose input parameters are air pressure <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$P$</tex-math></inline-formula> and winding number <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$N$</tex-math></inline-formula> , and output parameter is bending angle <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\beta$</tex-math></inline-formula> . Finally, through the finite element analysis, the optimal <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$N$</tex-math></inline-formula> is obtained, and the correctness of the model is verified. Additionally, the rehabilitation device is fabricated by using Kevlar fiber, silicone rubber and 3D printing. To verify the above research, an experimental platform is constructed. The results show that the relative error of the modelw is in an acceptable state. The device can imitate common gestures, produce a maximum fingertip force of 0.61 N, easily grasp objects with a volume of 1.6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dm^{3}$</tex-math></inline-formula> and mass of 335.7 g, which can realize the hand rehabilitation training.