3D measurement method of underground displacement based on Hall and MR effect

摘要

When the cylindrical NdFeB magnet was magnetized along the axle wire, the magnetic field around the magnet was symmetric about the axle wire. The output voltage of Hall sensor was proportional to magnetic induction induced by itself. Around the magnet, the magnetic induction component along the axle wire could be measured by Hall sensor. The contour line and contour surface of magnetic induction could be plotted by MATLAB. A sensor array was composed of three Hall sensors in triangular distribution, and 3D Cartesian Coordinate System was established. 3D coordinate of magnet can be measured with this sensor array based on contour surface. Underground soil deformation will change the relative position of sensor array and magnet. The size of geotechnical displacement can be calculated after getting the new 3D coordinate of magnet. Along with dual-axis magnetic sensor based on MR effect, the orientation of geotechnical displacement can be measured, and so able to measure the underground displacement.