The Development Of Fluxgate Magnetometer Based On An μCOS System

The fluxgate magnetometer is a kind of vector measurement device that applies fluxgate sensor to measure the magnetic fields. Compared with the traditional measuring magnetic field instruments, the fluxgate magnetometer has advantages such as high resolution, small volume, and good efficiency. The static magnetic fields and alternating magnetic fields can be measured with great speed, and directly. The fluxgate magnetometer has been widely used in many fields such as scientific research, national defense construction, industrial production and daily life.Traditional fluxgate magnetometer based on analog signal processing is more easily affected by the surrounding environment when measuring the magnetic field. With the development of electronic information technology,a fluxgate magnetometer has developed in the direction of digitization. For now the digital fluxgate magnetometers mostly use the computer for data acquisition and processing,which do not meet the requirement of equipment miniaturization. With the advent of high-performance single-chip computer in recent years, it greatly improves the performance of embedded computers, the miniaturization of fluxgate magnetometer.Aiming at the problems existing in the traditional fluxgate magnetometers, the author proposed a overall design scheme of the high speed fluxgate magnetometer based on the μCOS kernel. The μCOS kernel is applied in the embedded development environment of the preemptive operating system with great portability and tailor. Instrument software system adopts the μCOS operating system on ARM microcontroller, and divides tasks into different instrument functions. The managing and scheduling tasks of μCOS operating system ensures tasks synchronization between resources and actions at the same time. This can greatly improve the efficiency of system, and meet the requirement of real-time high-speed data collection system. Because the fluxgate magnetometer needs to save data in real-time.For a long time, the storage and management of sampling information is particularly important. System adopts the Fat Fs file system to establish and manage files, which greatly improves the efficiency of file management. Instrument hardware system adopts MCU STM32F103 with high performance and low power consumption as the main control unit.Through mag-03 fluxgate sensor probing and the 24 high precision synchronous ADC sampling signal from three axis, it can acquisite the weak magnetic signal in high-speed way. The STM32 microcontroller displays the data of three axes as waveform on the touch screen.The data after preliminary treatment would be stored as a fixed text format in the SD card. This article introduces the overall structure of the fluxgate magnetometer in detail, including design of instrument hardware system and software and analysising and validating data.Compared with the PXI collection device, the offset of X axis of fluxgate magnetometer is-6 nT, the offset of Y axis of fluxgate magnetometer is-5 nT, and the offset of Z axis of fluxgate magnetometer is-8 nT. The display and storge of three axes waveform all reach the design goals.