A Granary Storage Quantity Detection System Based On Laser Calibration And Image Processing

Grain is an important strategic material of peace and stability.Chinese grain reserves have the following characteristics: nationwide distribution,more species granary,large capacity of granary and so on.Chinese grain reserve is about 4million tons,which plays a decisive role in the macroeconomic control of national grain and the stability of grain market.Grain quantity detection is an important part of maintaining “Food Security”.At present,grain quantity detection include following methods: weighing method,pressure thansducer method and laser scanning volume method.Weighing method is inefficiency,a waste of manpower and material resources;Buried pressure thansducer measurement realizes the real-time detection of grain quantity,however,a large investment in construction is essential and precision is not high enough;For laser scanning volume method,although precision is high,scanning volume is time consuming,which cannot satisfy real-time requirements.In this paper,combining with advantages of both laser scanning and image processing,the laser calibration method is introduced into the image measurement,in order to develop a set of data acquisition and processing system.The main tasks are as follows:1)The device selection of a webcam.The control system based on stepper motor drive is designed.According to PELCO-D protocol and based on the C Programming Language realizing all kinds of motion control;based on high precision angle sensor,Laser calibration lamp and Laser range finder,with STM32 as the controlling core,the hardware platform of the slave computer is set up to meet the needs of the grain quantity detection system.2)Establish world coordinate system,camera coordinate system,and two-dimensional coordinate system.Using the classical checkerboard calibration method,calibrate the webcam and obtain the camera internal parameters,in order to accurately measure length and width of grain’s surface.3)Set up the nonlinear distortion model of webcam,according to Zhang distortion correction method,based on chessboard image obtained from multi angle shooting,call the “CalibrateCamera” method to obtain the webcam distortion parameter and distortion correction of the webcam.Lay the foundation for the calculation of grain surface area based on image.4)Call the EmguCV image processing library function,CvInvoke.cvRemap,to get two value images by Perspective transformation,Otsu adaptive threshold image segmentation and image enhancement.Prepare for accurate measurement of area under different angles of inclination.5)In the Visual Studio development environment,develop host computer system by C# language.Through the system,laser light can be controlled on and off,and the pan can be rotated to settle the laser light in the suitable position of the grain surface,so that pictures with laser spot will be taken;Based on the actual distance between light spots,obtain image spatial resolution,solve actual areal of grain surface.Multi range measurement of grain surface base on laser range sensor,grain height can be obtained.Finally,the quantity of stored grain is calculated.After several measurements in the laboratory,the overall measurement error is about 5%,Preliminary to achieve the desired results.