A Planar Cable-Driven Mechanism as a New Variable Stiffness Element

Design and utilization of a planar cable-driven mechanism as a variable stiffness element is investigated for the purpose of the noise and vibration control. The components of the stiffness matrix of a cable-driven mechanism as well as the tensionability criterion and the effectiveness of the stiffness control through antagonistic force control are studied. Two designs of planar mechanisms with variable stiffness are proposed and different aspects of their stiffness are presented and compared. The results showed that the total stiffness of these two designs can be changed 57% and 26%, respectively which means it is possible to build an effective variable stiffness mechanism by controlling the antagonistic forces. The results were verified using a nonlinear simulation. Finally, the linearity is improved by introducing a dual mechanism design.