Dynamics Identification and Control of Large Load Robots Considering Nonlinear Friction

In operation scenarios such as large component handling and machining, robot friction varies significantly with different loads, requiring accurate modeling of friction, dynamics identification and control of the robot system. In this paper, we propose a kinetic parameter identification and adaptive sliding mode control method considering the viscous friction nonlinear term. First, a robot dynamics model with viscous friction terms is established and the parameter space is reduced to obtain the minimum inertia parameter set; second, the excitation trajectory is designed and optimized, and a hybrid identification method combining the least-squares method with the interior-point iteration method is used to obtain the inertia parameter values with viscous friction indices; finally, the adaptive sliding-mode controller with friction compensation is designed based on the results of the identification model. Simulation results show that compared with the traditional method, the root-mean-square error of the theoretical and measured moments in the identification method of this paper is smaller, and the jitter of the system trajectory tracking process is reduced. The method is characterized by the integration of the viscous friction nonlinear term in the dynamics modeling, the inclusion of the viscous friction index parameter in the identified dynamics parameters, and the control process to compensate the friction feedback, thus realizing the high-precision tracking of the robotic system under the condition of large load.