Study On The Intelligent Grain Monitoring Device Based On The Auto-focus

Intelligent grain depot monitoring system can be used to measure and real-time monitor grain depot,which is of ignificance to grain depot safety management.A set of intelligent grain depot monitoring device based on automatic focusing is studied.Based on the existing automatic focusing technology the monitoring device is achieved measuring distance according to the function of the system parameters of the positive state,and image acquisition device real-time monitoring is achieved,so the comprehensive management of the granary both the real-time management and the automatic measurement are realized.The main research of the thesis include:(1)By comparing five kinds of measurement technology,the measurement method based on distance measurement sensor technology which is suitable granary static environment is selected.The principle and method of automatic focusing technology based on image processing is introduced.(2)Based on the principle of automatic focusing,the principle of the distance measuring system is put forward.The imaging principle of optical imaging system is analyzed,which shows that based on the Gauss formula the system is achieved imaging clearly through changing the focus.By analyzing and comparing the two auto focusing methods,the depth from focus is selected to realize automatic focusing.The method is suitable for the distance measurement system of the granary.Based on the depth from focus the improvement of the distance measurement system is proposed.(3)The evaluation of image definition and the search algorithm are two key steps in the depth from focus.The pretreatment method of image sharpness calculation is introduced,and the color image is converted to grayscale image.The four kinds of evaluation function curves are fitted by experiments.According to the criteria of single peak,non bias,high sensitivity,robustness andreal time,the Brenner function is selected.The principle and steps of four typical search algorithms are introduced.According to the criteria of accuracy,the amount of calculation,the feasibility,the hill-climbing search algorithm is selected.In order to solve the problem of low searching speed and low precision in the practical application of mountain climbing search method,the optimization method of setting reasonable focusing step is put forward to ensure the speed and accuracy of the ranging system.(4)The overall scheme of the distance measuring system based on automatic focusing is designed.The upper computer to display monitor screen,process image,and the lower computer to collect images,motor search.Five modules of the system are designed.The image acquisition module selects the USB camera,and the image sensor is CMOS.The image processing module uses the MATLAB software to realize the image definition evaluation.In the motor search module,two stepper motors are used to control the zoom ring and the focal ring of the lens,and the focusing is realized by changing the position of the mirror in the optical system.The transmission scheme and mechanical fixing structure are designed.MCU control module by setting the five step angle to achieve the mountain climbing search.The number of pulses corresponding to the focal ring and the focusing ring is measured by 20 sets of experiments,then distance curve is fitted,so piecewise function to calculate the distance is obtained.According to the principle of distance measurement system,the experiment process is described.(5)The relative error of the system is not more than 10% by the 40 groups of experiments,which satisfies the accuracy requirements.The error sources are analyzed from the motor search,curve fitting and human factors.The maximum variance of the same distance measured by 5 groups of repeated experiments is2.8117,which satisfies the stabilized requirement.The feasibility of the system is proved by the results.