A new methodology for joint stiffness identification of heavy duty industrial robots with the counterbalancing system

This paper deals with the joint stiffness modeling and identification of the heavy duty industrial robot with the counterbalancing system (CBS), which is important for the workspace optimization and deflection compensation in the robotic manufacturing. Shortcomings of the traditional method for the joint stiffness modeling and corresponding identification are analyzed in this paper. Motivated by the advantage and limitations of the traditional approach, a new identification methodology based on the servo motor current and corresponding position deflection is proposed to obtain the accurate joint stiffness. To validate the effectiveness of the proposed method for the joint stiffness modeling and identification, an identification and validation experiment is carried out using the HH-150 heavy duty industrial robot. The results show that the proposed methodology is able to identify the joint stiffness of the heavy duty industrial robot with the CBS, and the proposed new methodology outperforms in terms of accuracy, convenience and efficiency for the joint stiffness identification.