The performance of servo actuators is significantly affected by factors such as friction and backlash. Simplified analytical models have difficulty meeting the increasing demands of control systems. Therefore, this study proposes a new data-driven method for modeling nonlinear factors. Through experimental verification, the newly proposed modeling method significantly improves the accuracy of nonlinear models. This achievement provides strong support for the precise control of servo actuators.

Friction is widely present in moving mechanical systems, and it has a negative impact on the performance of mechanical systems, such as tracking errors during low-speed motion. To overcome the impact of friction on the control accuracy of the system, this paper proposes a dynamic continuous friction model based on numerous current friction models. Based on this friction model, the velocity control mode of the direct-drive system is compensated for, and good results have been achieved.

A novel hollow-ring permanent magnet brake integrated in robot joints is proposed, which allows the brake to require much less axial space and provides more than 1.5 times braking torque for the same volume as the conventional electromagnetic-spring friction brake. A coupled dynamics model of the proposed brake is developed from machine-electric-magnetic aspects. The 3D model of the brake is simulated through finite-element software. The theoretical models are verified through experiments.