Complete article Abstract: This paper proposes four types of conceptual models of the 6-DOF variable stiffness robot arms based on the antagonistic driven joints (ADJs). For convenience of control, the equivalent quadratic torsion spring (EQTS) is selected as the elastic element of the ADJ. The relationship between the output stiffness and the angular displacement of the EQTS is fairly linear. The elastic actuating torque of the ADJ is related to …Read More