Study On Automatic Control System Of Variable Spraying Based On Machine Vision

Herbicides and pesticides are spayed evenly in the whole fields or crops lines by general plant protection machinery, not considering the regional distribution of weeds and crops in space, which not only resulted in a large number of pesticide waste, but also pollution of the ecological environment and influence in the growth and yield of crops. Domestic and international studies have shown that it can save 40% -60% of pesticides if accurate application at the crop or weeds is used. At the foundation of summarized the domestic and foreign related research, this article studied an inter-variable spray control system which is based on the machine vision, also designed the software and hardware test platform for block spray control, determined the image processing algorithms and adjust various algorithms under the simulation in the laboratory. Ultimately the spray point between the variables is realized. The main research content of this article is as follows:(1) The methods of acquiring real-time motion image have been studied, and the rational allocation of collection equipment and the methods of obtaining a clear image of movement under light conditions have been analyzed. The real-time dynamic image acquisition prepared for further study of real-time processing of images in the fields.(2) The background of green plants has been divided through automatic threshold method. By comparing a variety of methods, it ultimately adopted the ultra-green method of image gray level, using Otsu automatic threshold method to detach green plants and the background of the partition. Tests showed that this algorithm has good adaptability, and has a good segmentation for the dynamic image.(3) Methods of positioning the center of the crop strains have been studied. As the crops are bunch planting and are regularly planted at uniform intervals along the line of growth, this paper presents the location of the characteristics of crops based on the over-segmentation positioning block projection method to locate the heart of crops. That is, on the gray-scale images of over-segmentation, most weeds are filtered out. The heart was determined in the over-segmentation, so that the positioning accuracy was greatly improved. Pixel blocks divided spray statistical discrimination according to the located crop heart, and ultimately to generate the corresponding control code spray.(4) A drive circuit using computer parallel port to control the solenoid valve was designed. After analyzing the current studies which adapted master-slave method to control solenoid valve, we proposed a control method based on the parallel port. Saving the Under-bit machine, we directly used the host parallel port resources idle to control solenoid valve. Experimental results show that the method can achieve good control of solenoid valve.(5) In order to precisely control the implementation of the spray hole, we need to determine relationship between the absolute coordinates with the world and that of the heart image the According to the principle of the camera lens imaging, we derived conversion formula between the coordinates of crop heart and coordinate, and its accuracy was verified by experiments.(6) A model that matches the Inter-hole variable spray control system was built. A machine vision-based inter-hole variable spray control system test platform has been build. The coordination of the various parts of the match in the system is the key to the accuracy of spraying. According to the features of hardware system for solenoid valves, pressure sprinkler systems and the mechanical properties, the experiment determined delay time of the system, integrated image acquisition and processing and finally derived the Inter-hole variable spray control system. It was certificated that it can meet the test of real-time processing requirements and the applied software. The use of VB and Matlab mixed programming method prepared machine vision-based inter-hole test variable spray control system software, laying the foundation for the further development of sprayer.