Impedance control and force estimation of a redundant parallel kinematic manipulator

Abstract

This paper presents impedance control through force estimation of a redundantly actuated Parallel Kinematic Manipulator. The impedance control is a model based control that sets a stiffness, damping and apparent inertia in the task space of the robot. The control is based on the feedback linearisation of the dynamics. The impedance control is achieved through an optimization promoting the even distribution of torques over actuators. Next, a force estimator is applied through an nonlinear disturbance observer. Finally, the estimated force is used in the impedance controller to set an apparent inertia of the moving platform of the robot. The approach shows a good response in low frequencies and good external force estimation required for impedance controlled tasks.