Soft Bending Actuator for Body-Powered Application

Abstract

Soft actuators are inherently compliant, highly dexterous, and lightweight alternatives to traditional electromechanical actuators in many robotic applications, especially human-interactive robots. This research aims to develop a soft robotic actuator that leverages body movements to mimic the function of human fingers to perform gripping and grasping tasks. Unlike the predominantly used chamber-based actuation techniques, this study involves braiding fibres along the axis at two different angles on each half of the cylindrical actuator. This angle difference allows the actuator to bend in one direction when pressurized by a pneumatic or hydraulic source. Furthermore, winding the fibres continuously along the axis increases bending by limiting radial expansion. As a first step, the bending concept based on variable stiffness has been validated using numerical and finite element analyses. Secondly, manufacturing a fibre-based soft actuator using materials of low Young’s moduli with a split fibre-reinforcement (SFR) technique was studied, followed by altering the fibre braiding pattern using the continuous fibre-reinforcement (CFR) method. The third study investigated the effect of Young's modulus on the bending and force output of the actuator. Additionally, a comparison was made between pneumatic and hydraulic-powered actuators. As a final step, the shoulder movements of the body were studied and utilized to power a set of actuators capable of performing gripping and grasping tasks. The low modulus materials and the continuous fibre winding technique allowed us to develop a portable, standalone, cost-effective body-powered prosthetic device.