Design of Reduced Order Disturbance Observer of Series Elastic Actuator for Robust Force Control

This paper proposes a new Reduced Order Disturbance OBserver(RODOB) for Series Elastic Actuators (SEAs). The SEAs assess the externally applied force by measuring the spring deformation. To control SEAs, Disturbance OBserver (DOB) has been widely researched to reject nonlinear disturbances and nominalize target plants to nominal models. However, parameter identification of the plant has a complicated process and demands expensive device. To address these identification difficulties, a novel DOB design which is simple and easy to apply is proposed.