Study On Filtering And Obstacle Imaging Of The GPR Detecting Signals For The Snow-plough

The phenomenon of snowing will persists 3 to 5 months every winter, in many cities in the north of our country. The heaped snow on speedways, highways and urban streets affects the traffic and people's living seriously, so the ways to clean heaped snow on the road in winter have been the research focus around the world over the years. To save the labour,the equipments and clean heaped snow on the road effectively, all kinds of snow-plough are being researched all over the world. We cooperated with the Chang Chun wan rong autocar refitting Ltd. to research and manufacture the sample of the multifunction snow-plough.When the snow-plough cleaning the snow on the road, the status under the snow is sightless for people's eyes, some obstacles may be buried under the snow. If the obstacles couldn't be found in good time and haven't taken any corresponding measures to avoid, the shovel and the road may be damaged, even the driver and other persons who are on the snow-plough will be hurt. So we use the ground penetration radar (GPR) to detect the heaped snow on the road, in order to find the obstacles under the snow in good time and exactly, and offer evidence for the shovel to fulfill real-time and automatic obstacle-avoiding.This research was conducted through the multifunction snow-plough project sponsored by the State Economic and Trade Commission. In this research the detecting of the heaped snow on the road is studied and the processing of the information which is obtained by GPR is researched. The specific work involves:Analyzing and choosing of detecting method for heaped-snow road. The feasibility of the sound-wave detecting method and the electromagnetic wave detecting method of the non-contact detecting methods to detect the heaped-snow road was discussed, and the electromagnetic wave detecting method was deemed fitting for the working circumstances of the snow-plough. In all the electromagnetic wave detecting methods, the marked virtues of the GPR detecting equipment are the diminutive size and the convenience of carrying about and so on. According to the theory of the electromagnetic wave radiating as well as the correlative experiments, the GPR was adopted to detect the heaped-snow road. The pivots of studying and the central matters in this paper is to analyze and process the reflected signals of the GPR and show the synchronous images of the obstacles which under the heaped snow on the road.One-dimensional analyzing and processing of the GPR reflected signal. The reflected signal of GPR in detecting the heaped-snow road contains multifarious interferential signals from its working environment. The central matter of the one-dimensional analyzing and processing of the GPR reflected signals is to filter the interferential signals. The one-dimensional analyzing and processing technology of the GPR reflected signals must be real-time with speediness and dependability to satisfy the real-time detecting of the heaped-snow road when the snow-plough works. The analyzing and processing method of the numerical signal contains the Fourier Transform (FT), the Shore-Time Fourier Transform (STFT) and the Wavelet Transform and etc. Their elements and characteristics are analyzed in this paper. The result of analyzing is that the Wavelet Transform is better to analyze and process the reflected signals of the GPR detecting than other methods.The Mallat algorithm of the Wavelet Transform that based on the Multi-Resolution Analysis is used to decompose and reconstruct the reflected signals of the GPR detecting, and the interferential signals can be effectively filtrated at the same time. The Daubechies wavelet of the Mallat algorithm is used to analyze and process the reflected signals of the GPR detecting, and its validity and real-time is simulated with the computer simulation technology. The validity and real-time of Daubechies wavelet of the Mallat algorithm for analyzing and processing the reflected signals of the GPR detecting is approved by the experiments of detecting the heaped-snow road with GPR.Two- dimensional imaging of GPR reflected signals. Based on the reflected signals of the GPR detecting, the purpose of constructing the planar image of the obstacles which under the heaped snow on the road is to provide the visual watching image of the obstacles for the snow-plough operator and enhance the security of the snow-plough when it is working. Based on the theory of the seismic wave radiating, the finite-differences time-domain algorithm, the Stolt migration algorithm and the Phase-Shift algorithm are the representative algorithms of the wave equation migration imaging algorithm. Their capabilities of the operating speed and the wave speed adaptability and the ability of full eliminating boundary influence and etc are discussed. The Stolt migration imaging algorithm is used to process the real-time imaging information. The GPR synthetic aperture imaging algorithm that based on the Stolt migration imaging algorithm is able to process the real-time imaging of the obstacles that is detected by the GPR. But the visualization of the image does not satisfy us. Based on the duality multi-resolution analysis algorithm of the Wavelet Transform, the image of the GPR synthetic aperture imaging which is based upon the Stolt migration imaging algorithm is decomposed and reconstructed. So the real-time image of the obstacles which are detected by the GPR is enhanced, and the visualization of the image which is provided the snow-plough operator to watch the obstacles which under the heaped snow is enhanced also at the same time.