Modular Multi-axis Elastic Actuator with Torque Sensing Capable p-CFH for Highly Impact Resistive Robot Leg

This study proposes a modular Multi-axis Elastic Actuator (MAEA) for legged robots that can effectively cope with impacts that may occur during dynamic maneuvering. MAEA has multi-axis compliance and can measure the torque without additional encoders. Therefore, effective impact resistance is possible with less volume and weight than conventional Series Elastic Actuators (SEA). The 6-axis stiffness analysis of paired-Crossed Flexural Hinge (p-CFH) is extended from small deformation to large deformation, and the accuracy is verified through Finite Element Analysis (FEA) and experiments. Based on the analysis, the torque of p-CFH is measured, and feedback torque control is also performed. Finally, the robot leg was constructed with MAEA, and the multi-axis impact resistance performance of MAEA was demonstrated by analyzing the applied impact during landing experiments at various angles.