One-Piece 3D-Printed Legs Using Compliant Mechanisms That Produce Effective Propulsive Force for Hexapod Robot Locomotion

Bio-inspired soft robotic legs can be designed by utilizing continuous deformation to perform desired functions such as increasing propulsion force. Previous studies of legged robots have improved locomotion performance by simplifying animal legs as a single spring and mimicking the function of its elasticity during locomotion. This study proposes a one-piece 3D-printed leg that can kick the ground backward strongly by increasing the horizontal component of the elastic force (i.e., by designing two-dimensional elasticity). The geometry and stiffness of the leg were optimized via a combination of physical simulation and a genetic algorithm to achieve the function. Experiments using a prototype hexapod robot were conducted to compare a leg designed using the proposed method and two additional deteriorated types of legs by measuring locomotion speed. Angle of attack (angle at which the legs touch the ground) was also changed in this experiment. The experimental results indicate that designing the two-dimensional elasticity of legs can contribute to increasing propulsion force, resulting in higher locomotion speed. This study suggests that soft robotic parts with various functions, such as hands and arms, can be designed using continuous deformation and one-piece 3D-printed parts.