Accurate Estimation of the Spring Stiffness in Series Elastic Actuators

In this paper the stiffness coefficient of springs using in Series Elastic Actuator (SEA) is obtained. The springs are assembled between the motor and the load of SEA. It is important to estimate the stiffness of SEA for controller design. By analyzing the mathematical model, an estimate method is proposed with the least squares method. The relationship of the rotation angle of the motor and the torque generated by the spring turns out to be linear and the coefficient of springs is obtained. The effectiveness of the proposed estimate method is verified by experiments.