| With the rapid development of digital products and office automation equipment,photocopiers are becoming an essential component of our daily life.However,there exist some limitations in current domestic laser copier domain.For example,foreign technology is monopolized so that domestic technology is weak,foreign products occupy most of the domestic market,and so forth.Therefore,the development of the copier technology can bring great economic benefits and strategic significances to the states.Especially in recent years,the government has emphasized more concerns on information security and the localization of office equipment,which can effectively protect the information security of citizens.Here we focus on the development project of our company's laser copier control system and some relevant researches have been carried out so as to improve the quality of reproduction.This thesis depicts in detail the working process and imaging principle of photocopiers.Based on the two-component photocopiers,we first analyze the importance of the total amount of toner dispensed in the developer mixing chamber to improve the quality of the copier.Then,the mathematical model for controlling the total amount of toner is constructed.And after that,a toner supply control system based on predictive control is designed and implemented so as to ensure the stability of the toner density and improve the quality of copies.Current toner supply control system has such characteristics as large time lag and nonlinearity that it is difficult to establish its precise mathematical model,and yet predictive control is an advanced control method which utilizes the input and output information of the controlled system in the past to predict the behavior of the system in the future.Due to the reasons that it does not rely on accurate mathematical models,predictive control can compensate for the inaccuracy of the control effect caused by inaccurate models,and predicts the characteristics of control-rolling optimization and feedback correction to make it highly robust and resistant to interference,and is therefore suitable for employing in the toner supply system.According to the development mechanism of the photocopier,a toner supply mathematical model is established,and based on which,we then construct a generalized predictive controller for toner supply control.The effectiveness of the generalized predictive control method for solving the toner supply control problem is verified by off-line simulation experiments.Considering with the overall design requirements of the photocopier control system,this thesis proposes an implementation scheme of Nios Ⅱ dual-core embedded system based on FPGA.Such scheme makes full use of FPGA's high computing performance and parallel computing features,as well as the advantages of SOPC system in simple software development,easy to write software code,short development cycle,and so forth.And then,this thesis discusses in detail the Nios Ⅱ dual-core hardware system design,including the Nios Ⅱ CPU processor and standard IP core configuration,Nios Ⅱ processor data communication program design and system software design.In order to improve the computing performance of the system,the FPGA hardware implementation of the basic operations in the predictive control algorithm is examined.Followed by analyzes the combination of the logic module with the Avalon bus module so as to guarantee the logic module becoming a true hardware accelerator which could be integrated into the dual-core system and called in the software program.To verify the validity and real-time performance of the FPGA-based Nios Ⅱ dual-core toner supply forecasting control system,experimental tests are performed on actual photocopiers.Experiment results show that the toner supply control system designed in this thesis has good control effectiveness.Compared with the predictive control algorithm implemented by software codes,the computing speed of the system is increased by about 7.3 times. |
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