Design And Implementation Of The Multi-functional Borehole Televiewer Based On OMAP4460

The borehole televiewer can be used to observe the lithological changes of the pore walls,structural fractures,fault karst and rock mass concealed outside the pore wall.It is widely used in engineering geology,hydrogeology,disaster geology,pipeline inspection and geomorphological survey during major engineering construction.At present,the borehole televiewer system on the market is basically a digital panoramic drilling camera device based on optical imaging technology and image processing technology,which can better realize the panoramic digital display of the borehole wall.However,it does not satisfy the engineering requirements of simultaneously observing the borehole wall and the front of the borehole.Because the probe structure blocks the front viewing.In addition,the borehole televiewer system should also be able to measure the drilling trajectory for the purpose of integrated hole measurement.In order to meet the needs of more practical projects,expand the application field of borehole televiewer technology,and solve more drilling exploration problems.In this paper,a multi-functional borehole televiewer system based on forward-looking probes is studied,which combines the function of imaging,inclination measurement,depth measurement and so on.The main research contents are as follows.Firstly,the related theories involved in the drilling imaging system are studied,which include the borehole trajectory measurement,the borehole image expansion and the borehole image splicing.According to the actual engineering needs,by comparing the volume,accuracy and cost of fiber optic gyro and magnetic sensor,the attitude measurement technology based on magnetic sensor is selected to measure the azimuth,elevation and roll angle of the probe.The improved ring map is quickly converted to a strip plan using an improved map-based panoramic image expansion algorithm.The seamless stitching of the bored image is completed by extracting features between adjacent images and calibrating the image in combination with the roll angle.Secondly,the functional requirements of the multi-functional borehole televiewer are analyzed in detail,and the overall scheme of borehole televiewer is designed.The OMAP4460 platform is selected because of its powerful graphics processing capabilities and it can perform signal processing,image display and trajectory rendering in real time.The probe consists of a constant current LED lighting circuit,a front camera and a magnetic compass is used to acquire images and attitudes.And it's connected to the host via cables.In addition,accurate measurement of the drilling depth can be achieved by a incremental photoelectric encoder,which is also connected to the host via cables.Thirdly,combined with the use and display requirements of the imaging system,the software framework of the function module and the display interface is designed based on the Android system,and the dedicated APP software developed realizes the functions of panoramic display,data storage and parameter setting of the drilling information,and improves the user experience.Finally,in order to evaluate the performance of the multi-functional borehole televiewer system,the functions,illumination intensity,camera resolution,magnetic compass accuracy and depth measurement accuracy were fully tested in the laboratory,and a surface hydrogeological observation hole was selected to conduct field measurements.The test results show that the borehole televiewer system developed in this paper has the characteristics of simple operation and beautiful interface.It has good working condition and accurate measurement results.It can complete the expected image information collection,trajectory information drawing and depth measurement,etc.,and meet the actual engineering needs.