Research And Realization Of Paper Color Control System In Paper-Making Process

Paper color is one of the external quality indicators which can be discerned by human eyes. As the improvement of people's living condition, the need of color on paper has been shown more diversity. At the same time, the demand of the color uniformity on paper is becoming stricter and stricter. As a result, the control on paper color and color difference seems to be very important.This thesis, combined the actual needs of paper-making corporations, has researched and realized the control system of paper color in this background. The thesis firstly explored the paper-making craft and the kinds of control method of paper color. Then we have studied the dyeing mechanism of paper and the color matching methods on computer, especially the Kubelka-Munk theory and the color matching theory of tri-stimulus values which is based on the Kubelka-Munk theory. Then we have analyzed the working and color measure principle of the color sensor illustrated by the example of TCS230.Considering the reality and application need, we have chosen the PID control method which has been maturely and widely used in the field of industrial process control. Then we have carried out the ordinary parameter tuning of PID controller, the simulation and analysis of the system according to the actual mathematical model. In order to improve the tuning efficiency of PID control parameters, we have brought in the Genetic Algorithm and realized the Genetic Algorithm according to the actual design issue. Next we have successfully found the optimal PID parameters with it and carried out simulation and analysis of the system.Finally, we have carried out the hardware design of the color control system based on FPGA chip. After broken the system into various sub-function modules, we have directly used the Hardware Description Language to design the error calculation module, the PID control module, the frequency division module, the Timer module and the PWM module. While we have realized the module of parameters calculation and color conversion in an approach of embedded IP soft core, combined with the SOPC technology. We have also carried out the function simulation and validation of every module.Seeing from the simulation diagrams of color control method, the control effect is fine and the final color indexes can tend to be stable at the settings. While the controller can successfully achieve the paper color control.The simulation waveforms of accomplished function module of the system have indicated that each module has already achieved the designated function and the intended target has been basically attained. So we have basically completed the design and realization of control system of paper color.The research works in this thesis provide some references for paper-making enterprises to control the paper color in the actual production. Combined with the paper-making corporations, further exploration and research can be taken to develop into products, which can be ultimately used in the actual paper manufacture.