Research On The Theory About Orientation Method Underground Using Electromagnetism

Our research mainly focuses on the three-dimensional position and attitude angle of drilling tool underground by means of electromagnetic distribution. Using three-axis accelerometer and three-axis magnetometer installed in drilling tool, measure its inclination, azimuth angle and instrument-oriented angle by means of coordinate transformation. By analyzing electromagnetic model of magnetic dipole source, design a suitable solenoid to transmit and receive magnetic field. By researching the spatial magnetic distribution of electric solenoid, analyze the subaerial orientation method based on single coil. While its measurement at a certain point can not directly determine the location of emission source, searching for the location should judge characteristic peak amplitude based on the relative amplitude of frontal and posterior received signal. Because single-coil orientation method is very cumbersome and time-consuming, we advance a subaerial orientation method based on dual coil. Arrange two coils plumbed each other at the ground. Orientate by comparing the positive and negative relationship between two signal amplitude instead of the size range of receiving amplitude. This orientation only determinate the two-dimensional position in the horizontal plane. In order to determine its position in space, it is necessary to determine the depth of drilling tool. This paper analyzes several methods of depth measurement--the calibration method, the double-coil method and the backwards and forwards anchor point method. Therefore, we can determine the three-dimensional position of drilling tool in the ground space. By researching error of measurement model of single-coil and double-coil theoretically, analyze the precision of two orientation methods. By determining the attitude angle and three-dimensional position of drilling tool underground, it is expected to control drilling direction real time.