Robust Control of Translational Cable-driven Robots

In this paper, a robust H-infinity controller is designed for a three-dimensional cable-driven robot. This robot is designed to have translational motions and the rotational motion is restricted. The proposed H-infinity controller guarantees the system stability during trajectory tracking tasks; however, it has less computational complexity in comparison with previous robust and adaptive controllers. The variation of robot's Jacobin matrix that causes nonlinearity in the system dynamics is taken into account as an uncertainty. In addition, the end-effector inertia and the friction coefficients of cable pulleys are also considered as other parametric (structured) uncertainties, and bounded disturbances are assumed in the system. The appropriate robust tracking performance of the controller is illustrated by performing some simulation studies on an uncertain cable-driven robot.