Investigation of the dynamic transmission accuracy of an industrial robot joint RV reducer under variable situations

The dynamic transmission error of the joint RV (rotating vector) reducer is one of the important factors affecting the positioning accuracy of industrial robots. However, the current studies on the transmission accuracy characteristics of RV reducers are based on the equal speed driving condition, which neglects the impact of the transmission error generated by the joint RV reducer on the positioning accuracy when the robot is in the start-stop variable speed phase. This study carries out an in-depth analysis of the dynamic transmission accuracy characteristics of joint RV reducers of industrial robots under variable-speed working conditions. Two typical mathematical models of variable-speed drive laws are constructed, and a multibody dynamic model of the RV reducer that takes into account the geometric errors of typical components is established, aiming to more accurately simulate the operating state of the RV reducer under actual working conditions. To confirm the accuracy of the theoretical RV reducer contact dynamics model, the dynamic transmission error test of the RV reducer under equal-speed conditions is carried out. The results show that the dynamic model can better reflect the actual transmission characteristics of the RV reducer. Thereafter, based on the theoretical model, the effects of different driving laws on the dynamic transmission error of joint RV reducers are analyzed in depth. The results of the study show that the transmission error of the RV reducer under variable speed drive is significantly larger than that under equal speed drive. Moreover, angular acceleration and load inertia are the main factors affecting the transmission error of RV reducers for industrial robot joints.