Mechanical Model-Based Decoupling Register Control For Roll-to-Roll Gravure Printing Systems

Roll-to-roll(R2R)gravure printing systems are a kind of complex industrial manufacturing system,which offer mass manufacturing of film products with color patterns through the continuous printing by the printing units.Registration is the position alignment between the patterns printed by different printing units.For R2 R gravure printing systems,precise matching of the different printed patterns can be achieved by accurate registration,which ensures and improves the product quality.However,the acceleration of the printing system,the tension fluctuation and register control in the upstream printing units will affect the registration of the downstream counterparts,which results in complex coupling phenomena and increases the difficulty of high-precision register control.In this dissertation,different mechanism models are established for the accelerating and steady-speed printing process of the electronic/mechanical shaft R2 R gravure printing systems.Based on the models,in-depth researches have been carried out on the problems in the existing register control methods,i.e.,the acceleration coupling,indirect decoupling,improper decoupling,incomplete decoupling,tension propagation coupling,complex computation.The details are summarized as follows:To solve the difficulty in the register control caused by the acceleration coupling in the accelerating printing process of the electronic shaft system,the dynamic characteristics of the accelerating printing process are analyzed in this dissertation.And a mechanism model is established by deducing the relationship among acceleration,web tension fluctuation,the register control quantity and register error of each printing unit according to the law of conservation of mass.Based on the model and dynamic decoupling concept,a feedforward proportional differential control method is proposed in which a feedforward compensation is derived to relieve the complex coupling among the acceleration,web tension fluctuation,register control quantity and register error.The effectiveness of the proposed mechanism model and register control methods is verified by an industrial example.For the problems of indirect decoupling,improper decoupling and incomplete decoupling of the existing register control methods for the steady-speed printing process of the electronic shaft system,a register error mechanism model is established in this dissertation on the basis of the law of mass conservation and Taylor approximation theorem.The coupling source is traced based on the model.With the consideration of the modeling error,the stability condition of the system is derived by using Lyapunov theory.Thus,a direct decoupling proportional differential register control algorithm is proposed to directly decouple the real coupling source.In addition,a new register error model is established to fully express the couplings in the system,which avoids the implicit coupling between the register errors of different printing units.Based on this model,a fully decoupled proportional differential register control algorithm is proposed.Finally,the effectiveness of the proposed model and control methods is verified by two industrial electronic shaft R2 R gravure printing systems.Aiming at the tension propagation coupling problem caused by the control action of the dancer rolls in the mechanical shaft system,the dynamic characteristics of the system is analyzed and a register error mechanism model is established in this dissertation.On this basis,a cooperative compensation is proposed to synchronously coordinate the feedback controls of the dancer rollers.In addition,the proportional differential feedback control parameters are adjusted and optimized according to the Lyapunov stability theory,the proportional and differential feedback control parameters are optimized.Finally,a cooperative compensation proportional differential register control algorithm is proposed,which can eliminate the coupling between the tension fluctuation and conduction,and the register error.The effectiveness of the proposed control algorithm is verified by an industrial example.To solve the problem of the complex computation of the model predictive control method for the R2 R gravure printing system caused by the complex coupling,a compensation is proposed in this dissertation to simplify the complex mechanism model of the system,which is designed on the basis of the decoupling matrix concept.According to the simplified model,a decoupling model predictive register control method is proposed.The effectiveness of the proposed method is verified by simulations.