The Study Of Fuzzy-PID Control To Glue-spreading In Middle Density Fiberboard

During the production of middle density fibreboard, glue-applying is the crucial working procedure. It affects the manufacture quality and the cost of production for middle density fibreboard greatly. In order to make glue-applying quality and fibre quality keep a exact mix ration and keep dynamic balance highly, the main task of glue-applying is to mix in reason and apply glue quantificationally to middle density fibreboard according to the change of the fibre quantity.This paper introduces the hardware and software structure of the glue-applying system according to the technology of glue-applying. The system adopts the top and down position machine structure, PLC being as the down position machine and PC being as the top position machine. The system realize adopting datum automatically, long distance transmission and the process control, achieving the real time - dynamic simulation and the monitoring the running state. The application of the OPC interface technology on the data disposal achieves the communication among different software and the datum incepting. The application of the frequency conversion technology and Fuzzy-PID technology on the glue-applying control achieve the frequency conversion and timing control for the glue-applying engine. The application of Fuzzy-PID technology solves the real time control problem without,building exact mathematic model and makes the glue-applying control accurately.It is very difficult to build the glue-applying model because it is disturbed by many different ingredients during the glue-applying process. It is difficult to reach high control precision because the common PID control can't reach system demands and the capability of the fuzzy controller is bad at eliminating system steady state error. This paper combines the common PID technology with the fuzzy control technology. The system steady state error may be zero by the integral accommodating function of the PID adjustment. The system has good function in eliminating steady state error. We can reach the real time control for the system by the system input and output result data in according to the fuzzy control characteristic without building mathematic model. The glue-applying quantity and the fibre quantity always keep the dynamic balance in theory.