Design optimization for a 2-DOF cable-driven joint with large stiffness range

Cable-driven manipulator has the advantages of lightweight structure and adjustable stiffness. As such, it is intrinsically safe for human-robot interactions as a service robot. This paper proposed a 2-DOF cable-driven joint module with variable stiffness. To increase the stiffness range, a variable stiffness device (VSD) with a compact configuration is proposed and optimized. A design optimization method for the 2-DOF cable-driven joint module is proposed to obtain a large stiffness adjustable range. The average stiffness adjustable range in the workspace is employed as an objective function to optimize the dimensions of the joint module with VSDs. The optimization result shows that the stiffness range and the workspace have been increased significantly.