Dynamic Creep Phenomenon on Polymer Cable with Non-linear Characteristics for Cable-driven Parallel Robots

Cable-driven parallel robots (CDPRs) are widely used in precision industries owing to more advantages such as large work-space, lightweight, and high velocity. A CDPR is actuated by polymer cables connected to an end-effector. However, the polymer cables for CDPRs have complex non-linear characteristics including structural elongation, hysteresis, and dynamic creep. These characteristics of the cables cause the non-linearly change of cable length, which makes the position error of the end-effector. In this research, we propose a nonlinear dynamic model based on the viscoelastic cable dynamic model to describe dynamic creep behaviors. The dynamic model is easily integrated with a scheme position control to increase the accuracy by compensating errors by cable elongation.