Design and validation of symmetrical elastic elements in series elastic actuator

In recent years, as robots are frequently required to interact with the external environment, the demand for robot joint flexibility has been increasing. Series elastic actuators (SEAs) are widely used in robot joints as typical compliant actuators. However, the stiffness model based on the classical beam theory has a large error with the reality, which raises the design difficulty. In this paper, the data obtained from finite element analysis is analyzed theoretically. A theoretical model of the stiffness of a typical symmetric elastic element is obtained. The design experiments are verified and the fitting accuracy is 98.27%, which is significantly higher than that of the stiffness model based on classical beam theory. It can be used to design elastic elements that meet specific stiffness requirements.