Design And Realization Of Masterbatch Machine Control System Based On Revised Butterworth Filter

In practice, it is normally concentrated on regulator and control strategy in designing automatic control solutions. However, the quality of sensors signal is often ignored. According to the practical experiences, the resolution of the sensors signal should be at least10times than the control precision requirement. It is stated therefore that assuring the sensors signal quality is important and necessary.At present, the weighing sensors have been widely used in the industrial process control. The weighing sensors have become inescapable parts and play a very important role in the field of manufacturing supply chain, import and export trade, intelligent logistics and so on. But because of electromagnetic interference, mechanical vibration and the other uncertain factors, the sensor signal is always contaminated by lots of noise which can cause a big effect on the signal reality. So we must take measures to undo noise.Now, most domestic weighing apparatus manufacturers use first order inertial filter or moving average filter to undo noise. Although the filter can weaken the noise to some extent, the filter did not met the needs of modern technical requirements in the place where requested high precision, such as Masterbatch machine of plastic and packaging industry. Therefore, this thesis has strong practical significance.In this thesis, we introduced historical background, current state and developing trend of the weighing technology firstly. In the following paragraphs we introduced operating principle and applications of several common weighing sensors. Then we described the design process of several common digital filters, including FIR filter, IIR filter and Kalman filter. And we also did some simulation to evaluate their filtering effects. Next, we introduced the complete system design about Masterbatch machine project. Firstly, we described the basic process of the machine and configure suitable hardware and software aimed at control area. Secondly, we tested these digital filters to watch their static effect or dynamic response in the project. In order to consider both the static performance and dynamic performance, we chose the filtering method by means of Butterworth filter in combination with Kalman filter at last. Finally, for the sake of achieving excellent control effect, we used fuzzy self-turning PID controller to improve the system control precision with fuzzy-control rules that engineers get from industry scene. We also gave the experimental results.In this thesis, an improved butterworth filtering method is successfully used in the engineering project. And the result of the experiment has been proved that the digital filter plays an important role in improving the signal quality of weighing sensors.