Stiffness and dexterous performances optimization of large workspace cable-driven parallel manipulators

Cable-driven parallel manipulators (CDPMs) provide an easy way to achieve large workspace since flexible cables can be readily stored on reels. Generally, cables are treated as massless and inextensible that can only be tensioned. But for large workspace applications, cable curve due to their self-weight must be considered. In this paper, a curved cable is modeled as the series of an inextensible parabolic cable and a flat elastic cable to accurately account for its curve effect. The stiffness and Jacobian matrices of CDPMs are derived, which provide quantitative representations of stiffness and dexterity of manipulators. An optimization model is presented to simultaneously improve the stiffness and dexterity by selecting proper sectional area of cables and other structural parameters. Numerical examples demonstrate the curve effect on the stiffness of manipulators and a remarkable improvement of the performances can be obtained by properly determining structural parameters.