Double Position Loop Design of AC Servo Drive System

Abstract

The loop controller of double position fully closed makes the AC servo drive system acquire a very high position accuracy and speed following which is hard to be achieved for time-varying parameters, load disturbance, AC motors and severely nonlinear controlled objects. For the system, the dynamic nature can be ensured by the inner position loop adopting PI regulation of half closed loop structure, while the stability and the immunity can be achieved by closed loop structures with the rings outside adopting dual-mode fuzzy control. This article analyzes the cause of positioning errors for servo motor and semi-closed loop structure. The article also explains how to design a two position closed-loop servo system based on fuzzy control by adopting the AC servo motor drive, the motor shaft back-end incremental photoelectric encoder to form the inner position loop and using the motion control card, the inner ring of servo system and the work platform of grating ruler to make up the outer position loop. Based on double position loop composed of three-dimensional laser processing gear, the accuracy of the three-axis linkage workbench position control and the speed following can be ensured, thus meeting the requirement of the laser subsurface engraving machine for high speed and high precision motion.