Experimental Study On Magnetic Field Characteristic Of Magnetic Marker

In Automated Highway System based on magnetic marker guidance, the navigation facilities refer to magnetic markers in the central road with same interval. It can be used to judge whether the vehicle is deviated from the central road by detecting the magnetic signal with the help of sensors installed in vehicle and the deviation degree between sensors and magnetic marker called horizontal deviation as well. The objective of vehicle automation control is to reduce the deviation to the minimum. The value measured by magnetic sensor is the magnetic field intensity or magnetic induction generated by magnetic markers. In order to achieve the horizontal deviation through the real value of magnetic induction, it is necessary to gain the magnetic field distribution of magnetic marker firstly. Therefore, this study has carried out the research on the characteristic of magnetic marker and the relationship between the value of magnetic field measured by sensor and horizontal deviation.The equivalent magnetic charge model and electric current model of cylindrical permanent magnet have been established and presented in this thesis. In cylindrical reference frame, the analytical expression of calculating the magnetic field of magnetic dipole has been proposed. Furthermore, the integral expression as well as the approximate analytical expression of any position outside the cylindrical permanent magnet has been gained using the expression of magnetic field distribution of magnetic dipole. Using the analytical expression system computing the magnetic induction with Matlab, it can be easy to get the distribution of X, Y, Z component of magnetic induction. Through designing experiments to measure the magnetic induction of different size and model of cylinder permanent magnet using 3-Channel Gaussmeter, the actual component distribution chart and magnetization of actual permanent magnet can be gained through comparing measuring and computing results. As well as gained the remnant flux density B_r. Through ANSYS finite element analysis software, the simulation and comparison has been conducted to the magnetic field of the different contour permanent magnet and different installation height for the same permanent. Thus, optimization plan to magnetic marker shaping and the installation has been proposed.The ratio function expression of magnetic induction 2 component to X component has been analyzed in this study. Taking X direction component B_x and Z direction component B_z as the coordinates horizontal, ordinate axis, the along track bias, the horizontal deviation surveys the spacing distinction same spot B_x, B_z forms in the plane disperses a distribution map, to the spots whose horizontal deviation are the same, utilizing the fitting a straight line method, establishing the horizontal deviation isoline. In the experiments, it is easy to gain magnetic induction X component and Z component at some position. The horizontal deviation can be gained through examining whether the spot in the horizontal deviation isoline is located on an isoline, or in two isolines. The experimental results indicated the establishment horizontal deviation isoline method is feasible. In the process of establishing isolines, if the measuring point density is bigger and the isolines are denser on the distribution, the pointing accuracy is higher.A platform has been developed based on magnetic field characteristics research of magnetic marker, magnetic signal examination, the relative motion between vehicle and magnetic marker, which can be used to simulate vehicle auto-driving on the test field based magnet navigation. Vehicle moving straightaway, S shape moving forward as well as accelerated motion etc has been designed respectively on the platform. The relationship between magnetic induction and horizontal deviation can be gained through measuring the magnetic induction in movement.