Realization of Fuzzy Control in an Auto Focusing System

The surface error of the workpiece, mechanical axis error, etc. will cause the defocus of the marking focal spot in the laser marking process and affect the marking accuracy. An important way to avoid defocusing is to introduce a focusing servo system to detect and compensate defocusing in real time. The critical angle method is selected to detect the focus, and the focusing servo system is established. According to the characteristics of linear and nonlinear coexistence of defocusing error curve, a focusing servo fuzzy controller is designed, which completes the linear control of defocusing error in linear area and the fuzzy control of defocusing error in nonlinear area. The focusing experiment results show that the focusing servo fuzzy control system can realize automatic focusing, and the focusing servo adaptive fuzzy control algorithm enhances the robustness of the control system and expands the dynamic range of focusing.