The Study On Fuzzy-PID Film Feed System Based On PLC

As the people's standard of living becomes higher, packaging machine industry is developing quickly. The vertical form fill & seal packaging machine is an important one which is applied to powder or grain. The velocity control of film is a puzzle in this machine. The general resolution of this problem is in the mechanical domain.This thesis takes PLC as core controller using fuzzy-PID control to solve this problem. The study of this method has theoretical and actual significance.This paper takes BZA600 continuous milk powder packaging machine (CMP) as the test facility. At first, it analyzes the operating principle and mechanical character of CMP. Then, based on these, it analyzes the elements that have influences on film velocity. At last, the fuzzy-PID control strategy is determined.The hardware system is designed using Mitsubishi FX PLC and its pulse generator unit. This paper builds the mechanical model and calculates the processional moment and maximum moment of load. Then, it explains some key problems such as the application of servo motors, and designs the control and current circuit.A fuzzy control table is designed using fuzzy box of MATLAB. The rescaling factors of fuzzy variables are determined based on test. The system control program is designed by macking use of GX-Developer 7.0 and ADP 6.0. In the end, by making use of consulting table, the system realizes the fuzzy-PID control.The actual film velocity is measured in open-loop control, fuzzy control and fuzzy-PID control modes. The analysis of the film velocity error proves the feasibility of fuzzy-PID control in this problem.