A flat torsional spring with corrugated flexible units for series elastic actuators

With the fast development in physical Human-Robot Interaction (pHRI), researchers have been focusing on compliant joints to ensure the safety of humanity. Series Elastic Actuator (SEA), basically consisting of a motor in series to a spring connected to the load, is an effective solution of compliant joints. In this paper, a novel flat torsional spring with corrugated flexible units for SEA is proposed to meet the requirement for the elbow joints of humanoid robots. Then a series of tests are performed in Ansys Workbench 15.0. Under 30 N-m torque, the torsional angel is 0.105 rad. The torsional stiffness is 288.5 N· m/rad. Compared to the simulation results of other existing flat torsional springs, the proposed structure has a lower torsional stiffness, which provides workers a better protection. What's more, it has a higher radial stiffness and a higher axial stiffness, which decreases the vibration and increases the control accuracy.