Quantitative Analysis of Load Characteristics of Six-Axis Force/Torque Sensor for Robots Based on Dynamic Model

The dynamic behavior of the six-axis force/torque (F/T) sensor mounted on the robot system’s wrist is notably impacted by the end-effector, thereby compromising the robot’s performance in physical interactions with the external environment. To achieve a comprehensive understanding of the dynamic performance, this article integrates the sensor and the end-effector into a unified dynamic system. By taking into account the inertia effects, a dynamic model is developed to capture the coupling between flexural and torsional deformations within the sensor structure beneath the end-effector, aiming to provide a more accurate description of natural frequencies and vibration modes. Based on Timoshenko beam theory, it is found that equivalent parameters in ${F} _{x}$ / ${F} _{y}$ are affected by both translational and rotational inertia of the end-effector. Moreover, simulations and experiments validate a linear relationship between the generalized mass (mass, rotary inertia, and coupling of mass and rotary inertia) and the reciprocal of the natural frequency square. The experimental results demonstrate the efficacy of the dynamic model in accurately determining the natural frequencies of various load masses across all sensor channels, with a maximum relative error of 1.006% between the calculated frequencies and the response frequencies.