Stability of impedance control of a series elastic actuator with a torque controlled actuator for improving the system performance

As a driving source of a robot arm, a series elastic actuator added with another actuator was used in this research in order to achieve a smooth movement at high power and with minimal size. A series elastic mechanism using a torsion bar and a high reduction actuator drove the arm, and the added low reduction actuator reduced the vibration characteristics of the arm according to the response delay of the high reduction actuator and the elastic system. In order to drive the proposed mechanism in low impedance, an impedance control method was adapted to the system. By comparing the results of the theoretical analyses and simulations, to those of the direct drive motor only and to those of the system without the low reduction actuator, we showed the effectiveness of our proposed system.