Experiments of impedance control on an industrial robot manipulator with joint friction

This paper describes the experience of implementing impedance control on an industrial robot manipulator in contact with a compliant environment. Due to the presence of gear trains at joint axes, friction effects strongly influence the dynamic behaviour of the controlled manipulator at low velocities. Since a manipulator in contact with an environment is typically required to operate at low velocities, counteracting such effects is of the utmost importance. For this purpose, two different control strategies are experimentally tested and a performance comparison is developed in terms of position tracking capability and force response.