The Research Of Liquid Level Measurement Based On Linear CCD And Optical Design

Liquid level is one of the most important and most common parameters in the industrial field and liquid level measurement is widely applied in chemical industry, petroleum, power plant and some other liquid storage devices. With the development of the modern optics technology and the optoelectronic technology, the precision manufacturing technology and the performance of the charge coupled device (CCD) have been developed quickly. So it is possible to detect the tiny changes of the liquid level by using the linear CCD.It is proposed that the liquid level images are directly projected onto the linear CCD without any optical lens by using light emitting diode to achieve liquid level measurement and a measuring device is designed for the proposed method.This paper firstly makes a detailed introduction about the liquid level measuring technology based on linear CCD, which mainly includes the working principle of the linear CCD,the research status and the superiority of the liquid level measuring technology based on the linear CCD and so on; At the same time, it mainly introduces the optical design of the liquid level measuring system. By using the PCI data acquisition card, the optical field distribution curves of LED are recorded. The analytic expression is given by processing the data with the conic fitting algorithm of Matlab. And it is needed to design the optical model and get the optimal solution of the model; The system is based on FPGA,DSP and some other digital technology. In the measuring system, FPGA is used as the control core to generate timing pulses and to control the main chips and DSP is used to process the image data and send data to the chip with the inter-integrated circuit (IIC) interface. At last, the measuring device of liquid level is treated with the calibration and error analysis.Finally, it is proved that the indexes of the liquid level measuring device are able to meet the expected requirements through the experiments in different environments, which provided some references for the further improvement and application.