The triaxial fluxgate magnetometers (TFM) are widely used in space exploration, positioning and navigation, geological exploration, etc. As a high-precision vector magnetometer, the measurement accuracy will directly determine the accuracy of the obtained magnetic field data. The TFM has three kinds of own errors in measurement: zero offset error, proportional coefficient error and non-orthogonal error. These three kinds of errors will cause the TFM to deviate from the actual magnetic field value, and the fluxgate magnetometer needs to be calibrated. At present, the accuracy of the calibration method adopted by the fluxgate magnetometer depends on the stability of the natural environment magnetic field and the triaxial turntable (there is an uncontrollable residual magnetic interference), which limits the further improvement of the calibration accuracy. And due to the wide application of electromagnetic equipment, the natural electromagnetic environment is further damaged, and the calibration accuracy is subject to deterioration. In this paper, a magnetic shielded room (MSR) is used to provide a near-zero magnetic environment, and a triaxial uniform magnetic field coil (TUMC) is installed inside the MSR to construct a controllable arbitrary vector direction magnetic field, which solves the magnetic field disturbance problem of the original method. The TUMC and TFM error models were built and the MSR magnetic ambient noise model was added. The emphasis is on the degree of distortion of the magnetic field generated by the MSR as a ferromagnetic boundary condition and the influence of the deviation of the center point of TUMC on the calibration accuracy. Then, based on the above error model and magnetic environmental conditions, the calibration accuracy of the calibration magnetic field distribution is analyzed. Finally, the calibration experiment of the TFM is carried out by using the existing MSR, which proves the feasibility and effectiveness of the calibration method, and the method can greatly improve the calibration efficiency.

The scalar triangulation and ranging (STAR) method is a magnetic method based on magnetic gradient tensor invariants. Due to the asphericity parameter, there are distance error and direction error in the STAR method. There have been studies to compensate the direction error, but the distance error has not been compensated. This paper proposes a new STAR method (NSM) that uses an iterative method to compensate both the direction error and the distance error. Considering the convenience and feasibility of the operation, previous researchers analyzed the detection accuracy of the magnetic method by the detection error of the magnetic target on a latitude trajectory. But different latitude trajectories will lead to different analysis results. In order to analyze the influence of motion trajectory on the detection error, the omnidirectional magnetic detection model (OMDM) is established. Based on the OMDM, the warp trajectory that accurately measures the detection accuracy is found. Simulation results show that NSW reduces the localization error of the STAR method, Lv-STAR method, and Wang-STAR method by 87.5%, 58.8%, and 12.5%, respectively. Both simulation and experimental results show that when comparing and analyzing the detection accuracy of the magnetic method, the results obtained by a latitude trajectory are one-sided, but a warp trajectory is both operable and accurate.

Distributed Magnetic Sensor System (DMSS) can measure vector magnetic field and magnetic gradient tensor (MGT) and is widely used in magnetoencephalography, geological exploration, magnetic navigation, magnetic positioning, and other fields. The posture and position of the magnetic sensor are the key factors that affect measurement accuracy. For the first time, using a magnetic shielding room (MSR) and a composite coil that can switch between uniform and gradient fields in situ, a new correction method for various errors is proposed to reduce vector measurement errors. In addition, sensor position deviation can also lead to MGT calculation errors. This paper establishes a compensation model by using the magnetic field gradient formula. The simulation results show that the average calibration errors of the posture and position of the magnetic sensor are 0.08% and 0.53%, respectively, and the measurement error of the MGT is reduced by four times. Experimental results in the MSR show that the measurement error of the vector magnetic field is reduced by two orders of magnitude and that of the MGT by one order of magnitude. Therefore, the new calibration method can effectively enhance the measurement accuracy of the DMSS.

Magnetic positioning technology is safe, practical, and cost-effective, and is getting increasingly emphasized in many fields such as biomedicine and geophysics. However, magnetic positioning methods have a positioning-inaccuracy-area (positioning error is significantly greater than that in the adjacent area). This paper establishes an Omni-posture error model to explore the variation law of the positioning error and finds that the included angle φ between the magnetic moment vector and the position vector determines the distribution of the positioning error. Using wireless communication to send commands and adjusting the current vector to change φ, we propose an avoidance method of positioning-inaccuracy-area (AMP). Simulation results show that when using the AMP to track a wireless capsule endoscope (WCE) with an arbitrary posture, the positioning error is 5.5 mm and the orientation error is 1.64°. The experimental results in a magnetically shielded room show that the positioning error of the AMP is 12 mm, which reduces the positioning error before avoidance by 95.5%. The simulation and experimental results both prove that the AMP can effectively avoid the positioning-inaccuracy-area of the magnetic positioning method, thereby improving the positioning accuracy.

Standard gradient magnetic flux (GMF) is widely used in the research and development of biotechnology, and error calibration of magnetic detection systems, and can directly support the development of life sciences, geological exploration, ocean exploration, space exploration, and other fields. Because a magnetic shielding room (MSR) can create a noise-free environment (within a static magnetic field less than 0.2nT and magnetic noise less than 10fT/√Hz), the construction of a standard magnetic gradient source in MSR will further promote the detection accuracy of related technologies. The existing gradient coil design methods can’t achieve the best uniformity in a certain uniform zone. In addition, when the gradient coils are placed in the MSR, the magnetic and conductive materials of the MSR will further deteriorate the uniformity. In this essay, the calculation model for the magnetic flux gradient value of the coil in the MSR is formulated firstly. On the basis of the calculation model, a design method for gradient coil with optimal uniformity in any uniform zone is proposed. The new method can realize the design of improving the uniformity index for any uniform zone, and take advantage of the adverse factor of ferromagnetic boundary conditions introduced by MSR to make the gradient uniformity better. Meanwhile, in the research process of the design method, the coil volume utilization and efficiency are introduced into the design evaluation process through analysis, avoiding the singular result that the volume utilization and efficiency are less than 1/10 of the normal result, and the limitations of the design ability of the new method have been significantly improved. Finally, the core parameters of the new coil at different working conditions are summarized, which can be intended for leading the rapid gradient coils’ design. The validity and accuracy of the new approach are proved by finite element simulation and experiment. And the experiment shows that the uniformity of the new coil is improved from 44.79% of the traditional coil to 23.47% with ΔG decreasing by 47.6%.