EtherCAT-based Impedance Control of a 6-DOF Industrial Robotic Manipulator

This paper presents an etherCAT-based impedance control method for a 6-degrees-of-freedom (DOF) industrial robotic manipulator. After describing the overall system structure of this impedance controller using EtherCAT communication network, the forward kinematics of the manipulator is then derived using its Denavit-Hartenberg (DH) parameters. Based on the forward kinematics model and geometrical configurations of the robotic arm, an analytically inverse kinematics method is proposed to find the six joint angles of the manipulator moving from one point to another. For impedance control, a PI impedance controller along with a 6-DOF force/torque sensor and six independent PID torque controllers is proposed to achieve impedance control with satisfactory performance. The effectiveness and merit of the proposed inverse kinematics method and impedance controller are well exemplified by conducting two simulations one experiment on a really 6-DOF industrial robotic manipulator from HIWIN.