Static and dynamic analysis of a 6 DoF totally constrained cable robot with 8 preloaded cables

In this paper, the static and dynamic performances of a cable-driven parallel robot (CDPR) are analyzed over all its entire workspace. The considered robot has 6 degrees of freedom and it is completely constrained with 8 cables. This paper aims at highlighting the effects of cable preloads on the robot’s behavior. To this end, the stiffness matrix of the robot is computed from a second order approximation of the deformation energy of preloaded cables. Lagrange formulation is used to obtain dynamic equations of the robot for vibration mode calculation and trajectory tracking simulations. Static and modal analyses show that, for a given preload, the increase in the robot’s stiffness and modal frequencies is relatively more significant using soft cables, made of nylon, rather than stiff cables made of steel. These results are confirmed by dynamic simulations illustrating the effects of preloaded cables on the accuracy of trajectory tracking performance.