Development of high-precision magnetic compass sensor based on magnetic induction

Abstract

In this paper, we design a kind of magnetic compass sensor based on magnetic sense effect. The core of 3D magnetic sensor in each axis using Pomo alloy material molded to form a cylindrical core structure. Three axial magnetic core fixed on the polycarbonate plastic base is tightly matched with epoxy resin adhesive between the core and the base, which forms three-dimensional integration core structure and ensures the orthogonal angle deviation of three axial corresponding surface of the core is less than 0.5 degrees. The excitation circuit applying excitation to the magnetic induction coil of the magnetic sensor forms a pulse signal by adjusting the parameters of the hysteresis comparator, which makes the magnetic field intensity signal converting to the frequency signal. Pulse signal excitation is used to effectively reduce the power consumption of the magnetic sensor detection circuit. In FPGA, there are three independent high-precision frequency meters, which take the synchronous sampling of 3D magnetic induction sensor of positive and negative excitation frequency signal, do the signal frequency time synchronization arithmetic processing, and real-time output the digital signal of three-axis magnetic strength. The method of circular rotating extreme value correction is adopted to compensate the interference of soft and hard magnetic in environment. At the same time, the DSP processor is used to collect the three-dimensional acceleration sensor signal with intelligent attitude self compensation technique, so the magnetic compass has a good ability to adapt to the environment. After verification, the magnetic compass sensor has characteristics of high precision, high stability, low power, small volume, intelligent self compensation function, and the absolute error is less than 0.5 degrees.