Research On Color Registration Control Of Roll-To-Roll Process Based On MPC

Roll-to-roll(R2R)printing systems are widely used in industrial manufacturing systems due to their ability to mass produce continuous,flexible,and elastic materials.During the printing process,the web is transported from the unwind and infeed section to the printing section,where each printing unit prints a corresponding graphic(and marking)on it.Different patterns are printed sequentially by the printing unit,and the roll paper with complex patterns is collected into the winding part.Printing registration is the alignment of different patterns(marks),and color registration error is the gap between different marks.Preserving color registration errors at a high level of accuracy is critical as it determines the value of the product.However,the R2 R printing system is a rather complex coupling system,and upstream color control and fluctuations will cause downstream color registration errors.Therefore,it is a challenging problem to design a control method to preserve the registration error at a highprecision level.Based on the above problems,aiming at the steady speed and accelerated printing of the electronic axis printing system,this paper deduces the discrete mathematical model between the rotation speed of the printing plate roller and the color registration error,and on this basis,this paper focuses on the problems of model predictive control(MPC),error model fitting,compensation amount verification,improper decoupling,large amount of calculation,low control accuracy,and poor robustness in the steady speed and acceleration stages.The research details are as follows:(1)In view of the strong coupling of the roll-to-roll printing system,the difficulty of direct application of traditional MPC control,and the large amount of calculation,this paper decouples the roll-to-roll color registration system,simplifies the mathematical model,and obtains its corresponding state space model,and then apply the model predictive control algorithm to the model,and propose a fully decoupled model predictive control algorithm in the steady-speed stage.This method solves the problem that it is difficult to apply MPC to rollto-roll systems,and it has higher control precision and smaller error fluctuations compared with traditional MPC and fully decoupled proportional-derivative control.(2)In view of the problems that the roll-to-roll printing system will produce large tension fluctuations and large registration errors during the printing acceleration phase,and the acceleration phase model does not have a good decoupling method,this paper establishes the acceleration phase model,and calculate its compensation control quantity,then deduce the MPC optimization objective function,obtain the calculation method of MPC control quantity,and then obtain the piecewise linearization MPC control method.The correctness of the acceleration model is verified by open-loop experiments,and the superiority of this control method over model-based feedforward proportional differential control is verified by closed-loop experiments.Finally,the anti-interference analysis is carried out.Although this method improves the registration accuracy in the acceleration stage,it is not obvious,the control amount is relatively large,and the anti-interference is poor.This method preliminarily solves the problems of large tension fluctuations and color registration errors in the acceleration stage of the roll-to-roll system.(3)In view of the problems of the piecewise linearized MPC control method such as insufficient control accuracy,large control amount,and poor anti-interference performance,this paper improves its Laplace transform and discretization methods based on the existing timedomain mathematical model of the roll-to-roll printing system,and Applying model predictive control to it,a model-based model predictive control method is designed to reduce color registration errors caused by tension fluctuations.The validity of the method is proved by the simulation and experiment on the gravure printing machine model.The method significantly reduces the color registration error in the accelerated printing process,makes the control process more stable,has better anti-interference ability,solves the above problems,and verifies the effectiveness and feasibility of the control method.