| Water level meter is an application equipment, which is able to measure the water level of the boiler, using the principle of the communicating vessels . The meter , which utilizes the water and steam have different refractive indexes , can display different colour between steam and water i.e. steam presents read and water is green and if the boiler is full of water, the pair of water ducts only show the green . In the practice ,it is hard that the workers close to the boiler to read the position of the water level . To solve this problem , some apparatuses are used ,such as vidicon,monitor and so on ,to watch the water level meter , but the effect of objective image are influenced by background lightness diversification which brings on chroma distortion and image as well as staff suage blur, and other colour interference around water level meter . So the water level read by workers is unreliable.Based on above problem , this paper proposed one scheme which processes the watching images collected by vidicon ,restrains the background disturbance ,enhances the chroma information of the water level ducts, ensures the position of the water level and computes the high of the water . This scheme improves the traditional supervisory system . Then the watching images having been proposed are transmitted to the monitor. After characteristic of watching image of the water level meter is analysed carefully, with the colour recognition being a developing point ,this manuscript proposes three water level intelligent interpretation algorithms .And three methods are simulated separately by computer. 1,Water level meter interpretation based on feedback information. Because the colour structure of the water level ducts is that the upside is red and the underside is green, if the pixels of one columniation include the red as well as green pixels in the monitored image , it may be the position of the ducts . Based on this characteristic , this context proposes the scheme of water level meter interpretation based on feedback information , which is more effective than the one without feedback information in the aspect of restraining background interference and enhancing the chroma .So this scheme reduces the complexity of water level meter interpretation at the same time computes the high and ensures the position of the water level more exactly.2,Water level meter interpretation based on row processing . Because the background lightness value is smaller nearby the water level ducts , which is different from rest part except a pair of ducts in monitor image , one water level meter interpretation algorithm is presented , which handles the chroma ,background lightness and scale correlation characteristic synthetically , based on the row processing . Using this algorithm , the position of the ducts is fixed , the background interference is restrained and the chroma of the objective is enhanced . At last ,the level intelligent interpretation is realized.3,Water level meter interpretation based on multi- wavelets. Wavelet is an"time-scale plane"analysis method. Note that wavelet analysis is compact support both in time and in scale(frequence),so that it can provide an"adaptive transform"window structure in time-frequence i.e. it can adjust the time and frequence resolution based on praxis need. As we know, one of wavelet characteristics is wavelet multi-resolution analysis. In low frequence part, it has higher-frequence resolution and lower-time resolution and in high frequence part, it has lower-frequence resolution and higher-time resolution, which overcomes the shortcoming that the short time Fourier transform analyses unstable signal with single resolution. The wavelet resolution analysis is more suitable for checking signals as well as unfolding the components, so wavelet transform is called to the'microscope of analysis signal'. Based on the feature of two integral signals of the red and green chromatism and the lightness , water level meter interpretation algorithm based on multi-spatial'hybrid wavelets'is presented . The step of this method is threefold. Firstly, the position of the ducts is fixed, the background interference is restrained and the chroma of the objective is enhanced by the scheme of multi-wavelets analysis. Secondly, the landscape orientation integral signal of the red and green chromatism is analyzed by wavelet resolution analysis method. Thirdly , the water level is ensured and the high of the level is computed.In this paper, the mathematical description is presented separately for above three algorithms, at the same time, many pictures shot from the scene are tested by MATLAB simulation tool , using the three independently , and at last capability analysis and the result of the experiment are given .Simulation results show that water level meter interpretation algorithms are feasible and robust adaptability.For carrying out embedded application of water level meter interpretation, in this paper ,an embedded video process platform is designed and realized , based on DM642.The selected DM642 video signals processer ,which is one processer chip of TI company, is designed specially for video process. It remains'strong'computational capacity of the series of C64xx and provides many video process interface, based on the C64xx , which predigest peripheral circuit designment remarkably . The embedded video process platform, which is based upon DM642 , includes five parts : DM642 processer chip, video input , video output , data memory and I/O interface. Note that the main function of the video input is that it converts analog video image to digital ,and it transmites to DM642 cache by video port ,and then the digital image is processed by DM642. When it is done that the digital video image is processed by CPU ,video output converts the digital to analog signal , and then the monitor displays the image .Such is just main function of video output. Data memory consists of SDRAM and FLASH . Note that SDRAM is extended memory of DM642 ,which satisfies the need of high computational cost when the video image is being processed . FLASH is a nonvolatile memory memory ,which is used to save procedure and runs the procedure automatically . I/O interface , which adopts CPLD , achieves to control man-machine interface .In the end , based on the embedded platform , the embedded appalication test realizes level intelligent interpretation , using above three water level interpretation algorithms . Experimental results show that interpretation system ,which achieves to moniter and interprete water level very well , can show the high of water in the boiler automatically ,so it provides one chance for carrying out closed loop self-motion control of the boiler and insures the boiler works in one safe condition. |
PDF Full Text Request