Application of A Reliable Dynamic Friction Model for Accurate Dynamic Model Parameters Estimation of Robot Manipulators

A precise dynamic model is critical for collaborative robots to achieve satisfactory performance in model-based control or other applications such as dynamic simulation and external torque estimation. However, due to nonlinear friction behavior in robot actuation, it is difficult to identify precise dynamic parameters. In this paper, a reliable dynamic friction model, which incorporates the influence of temperature fluctuation on joint friction, is utilized to increase the accuracy of identified dynamic parameters. First, the friction of the joint module is investigated. Extensive test series are performed in the full velocity operating range at temperatures ranging from 23°C to 51°C to investigate friction dependency on joint module temperature. Then, dynamic parameter identification is performed using the inverse dynamics identification model and weighted least squares method. Based on the friction model identified in the first step, friction toque is computed, and the effect is eliminated by subtracting it from experimental data for dynamic parameter identification. Finally, the proposed notion is verified experimentally, and the results demonstrate that using a precise dynamic friction model improves the accuracy of dynamic parameters identification.