Abstract:  Aiming at the problem that the dynamic accuracy was affected by the nonlinear factors in the ball screw fullclosedloop servo system, a hybrid control strategy was designed. Firstly, for the friction factors in the system, feedforward friction compensation based on the LuGre model was adopted. Then, in order to improve the accuracy of friction parameter identification, an improved chaos particle swarm optimization algorithm was proposed. The convergence process of the particle swarm was divided into three stages by the algorithm. The search methods of large inertia weight, variable inertia weight and chaos optimization, and small inertia weight were used to gradually improve the convergence accuracy and avoid falling into the local optimal solution. Finally, in view of the gap factor in the system, a speed compensation strategy based on reverse motion monitoring was designed to improve the dynamic characteristics of the reverse motion of the gap system. The simulation experiment shows that comparing with the conventional particle swarm algorithm, the improved chaotic particle swarm algorithm reduces the absolute error of parameter identification by 42.6% on average. Experiments based on the given experimental platform show that the hybrid control strategy using LuGre friction compensation and reverse speed compensation can shorten the speed following error by more than 50%, reduce the position error of the system during reverse motion, improve the overall position tracking accuracy, and meet the dynamic characteristics of the CNC system.

Key words:  fully closed loop control; friction compensation; LuGre model; gap compensation; chaos particle swarm

HUO Xiao-rui, ZHAO Xian-chao, SHI Ji-chao, et al. Ball screw servo system based on full closed loop control technology［J］.Journal of Mechanical & Electrical Engineering, 2021,38(9):1124-1131.