Research On Predictive Control Of Mixed And Used Glue Process For Particleboard

During the process of producing particleboard,control level of mixed and used glue process has a direct influence on the physical and chemical properties of particleboard and formaldehyde emission.This paper combines with National 948 project,the title of which is"Key technology of diagnosis and control for wood-based board used glue"(2006-4-109) and HeiLongJiang Province scientific and technological project,the title of which is"Research on intelligent NC system of mixed and used glue for particleboard"(GB06A505). Through studying predictive control theory and related technology,put forward the process of particleboard an advanced predictive control technology is proposed basis on deeply analyzing production technology control mechanism of mixed and used glue for particleboard,Main research contents are as follows:For dynamic weighing accuracy problem of various raw materials in mixed glue process, dynamic weighing model is established by the means of analyzing control mechanism of this process.Then an kind of iterative learning control method for used glue is designed.Through controlling mixed glue system,the deviation between output track and given track is used to rectify the non-ideal control signal.By doing so,new control signals will be generated.With these new signals,system could be able to deal with mixed glue control system with a higher incorrect degree in a simple approach.And it only depends on less prior knowledge.During the process of used glue,problems such as delay of tracking in real-time and inaccuracy of used glue are generated.An improved generalized predictive control method is proposed.This method based on theory of generalized predictive control.And the method describes predictive control model of the glue flow used on surface layer by controlled autoregressive moving average model CARIMA.And through analyzing equivalence of GPC and DMC control laws,parameters of optimal control law could be inquired.The simulation results show that the method could effectively improve the accuracy of controlling used glue' s volume and exhibits strong robustness to problems exited in used glue on particleboard surface layer control system,such as delay,variation of paramaters.For the nonlinear property existed in the process of used glue,a research is carried on typical nonlinear Hammerstein model with identification method.However,consistency of linear parameters estimation can not be guaranteed by common algorithm.In these circumstances,this paper presents a new idea.The nonlinear static module of model is described by using LS-SVM model.And the linear dynamic module is identified by structure of state space model.The sparse problem caused by converting problem of quadratic planning into problem of linear equations is also solved.The simulation results show that the method enhances the robustness of Hammerstein model,improves the accuracy of the model identification,and reduces the time consumption of model identification.In the process of used glue,there are problems,such as the response of glue flow to core layer particle flow is slow,significantly delay and obvious nonlinear.The predictive founction control(PFC)method based on improved Hammerstein model is proposed.The method will be used to structure glue control input,and to consider every control input added in every moment as a series of pre-selected linear combination of basis functions.Therefore,the input regularity of control value is more evident.And through utilizing Hammerstein model,nonlinear system' s control of used glue on core layer is divided into two parts.The one is dynamic optimization of linear system' s module.The other is statically finding roots of nonlinear module.Simulation results show that the method can improve the rapidity which is used to measure the response of used glue on core layer,and enhance robustness of used glue control system.Research on anti-interference problem of used glue process control system for particleboard.Used glue control system is designed based on KPFC-PI.In system,ratio device and PFC work as system' s outer loop used to improve tracking speed and robustness.PI controller is worked as system's inner loop and used to improve anti-interference of system. Through adjusting PI parameters and fitting simplified inner loop,the entire inner loop worked as generalized object of the outer loop.By doing so,the deviation caused by interference will be reduced.The simulation results show that the method can effectively improve the accuracy of used glue on core layer for particleboard,maintain stability of used glue volume and possess a strong performance of anti-interference.Combined with theoretical researches mentioned above,a simulation experiment is carried on.Mixed glue simulation results show that the use of iterative learning method for constructing iterative learning factor q can adjust advance closure volume u to ideal setting value with rapid speed;Mixed glue experimental results show that the use of iterative learning control can effectively improve the accuracy of mixed glue,and ensure the accuracy of additive ratio.Used glue simulation results show that among three types of control methods mentioned in this paper,KPFC-PID control method has the strongest anti-interference ability, generalized predictive control method responds better,and predictive functional control method based on the H model deals with nonlinear situation much better.