Control of a 3-DOF Parallel Wire Driven Stiffness-Variable Manipulator

Parallel wire robot (PWR) is a bionic mechanism manipulator, whose flexibility of wires is similar to the compliance of human muscles. In this paper, a 3-dof parallel wire driven (PWD) manipulator configuration is presented, and the modeling and the tracking control of this kind of robot is studied. In PWD manipulators, the elastic units (wires) which are in parallel make the coupling and the nonlinearity of the model increased. So a singular perturbation theory, based on which the two-time scale control law can be obtained, is chosen as the control strategy. Then, according to the stiffness analysis results, a stiffness control law which can separate stiffness control from position control is designed to realize a variable manipulator. At last, a numerical simulation is provided for verifying the theoretical researches on tracking control and stiffness control