C7: Biomechanics


Yi Sun, Xinquan Liang, Marcelo H. Ang Jr., Chen Hua Raye Yeow

National University of Singapore, Singapore

The research field of soft robots is currently growing at a staggering rate due to its friendly interaction with human and delicate objects, and the superior capability in biomimicry. As a typical type of soft robot and actuator, silicone-based soft pneumatic robots and actuators (SPRA) are widely utilized in a multiplicity of applications such as rehabilitation and manipulation. However, one of the fundamental and challenging problems is how to utilize soft silicone of low viscosity to produce SPRAs capable of high force/ torque output. From the prior art, it is believed that high force output highly relies on the high stiffness of the silicone rubber. However, high stiffness represents the high viscosity of silicone rubber prepolymer which usually raises the difficulty in fabrication greatly. In this work, we propose a method to mechanically program the soft silicone into hybrid materials of any stiffness. This approach, inspired by Pulse Width Modulation (PWM), is to combine two types of materials of different stiffness at certain ratio into a hybrid material with an aggregated stiffness. In our specific experiments, soft silicone (Ecoflex 0030) represents the soft material while non-stretchable fabric is chosen as the stiff material due to its strong adhesion with silicone rubber. To guide the elasticity customization, a generic model is established. Tensile tests were implemented on the hybrid materials of different fabric-silicone ratios. Results show that our method is able to modulate the elastic modulus of the hybrid material while the comparison between the model and experimental results indicates a proper accuracy of our model. Our future work will include the application of this material customization method to the fabrication of SPRAs and ultimately produce SPRAs of high force output from soft silicones.

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