Aiming at the problem of the failure of the global positioning system in the satellite denied environment, and facing the needs of the navigation and positioning in indoor space, the technology of indoor magnetic field vector positioning and navigation have been studied. Based on the geomagnetic matching technology, the wavelet analysis method is used to estimate the noise components and statistical characteristics of the magnetic field three-dimensional signal; combined with the Kalman filtering algorithm, through estimating and optimizing the magnetic field vector signal, an indoor magnetic positioning signal processing algorithm with wavelet analysis and Kalman fusion is established, realizing the optimization of the measurement accuracy of the geomagnetic signal and the accuracy of the fingerprint map. The experimental results indicate that the signal-to-noise ratio of the test sequenceis increasedby 3db, the rootmean square error is reducedby about30%, and themaximumpositioning error reaches 1.34m, which can meet the requirements of indoor positioning.

The metal wear debris in mechanical transmission can feedback the characteristics of mechanical equipment failure, and its online monitoring efficacy directly affects the operating performance of mechanical equipment. Specific to the need for online fault detection of the mechanical transmission system, a double-coil reverse excitation method is adopted to provide a magnetic field environment for metal wear debris testing in the lubricating oil circuit of the mechanical transmission system. Based on the magnetic field distribution model of a single-coil solenoids, a coupling magnetic field distribution model of reverse-symmetric double-coil magnetic excitation is established. On the basis of detecting the coils to obtain the signals of magnetic field disturbance when metal water debris passing through the magnetic excitation field, an online monitoring sensor for metal wear debris with a reverse-symmetric double-coil magnetic excitation balance magnetic field is developed. Taking the monitoring of metal wear debris in a large-aperture flow channel as an example, a semi-physical simulation test has been carried out on metal wear debris in different grain diameters and textures, whose experimental results indicate that this sensor can detect $100 ~\mu \text{m}$ ferromagnetic metal and $1000 ~\mu \text{m}$ non-ferromagnetic metal in an 8 mm flow channel, which, as a detection sensor for metal wear debris, can also be used for metal wear debris monitoring in the mechanical lubricants of mechanical transmission and engines.

Specific to the full-range detection demand for the magnetic anomaly targets such as metal in shallow strata, transportation pipelines, and mined-out regions during the geophysical survey, based on the transient electromagnetic method, using the Gauss inverse Laplace transform, a magnetic excitation model for metal targets in medium-shallow strata is proposed. By using the adjustment of the electrical parameters such as frequency, amplitude, and phase of the excitation current, a spatial multimode magnetic excitation field is formed, an array magnetic excitation detection device is developed, and a distribution model for the array magnetic excitation field is established. The hardware-in-the-loop simulation results show that the frequency and amplitude of the excitation signal are directly proportional to the spectral amplitude and the induced amplitude of the secondary field of the signal, where the signal has the most spectral components when selecting a frequency of 25 Hz. The duty cycle of the excitation signal is of nonlinear correlation to the magnitude of the signal frequency spectrum. When the duty cycle is 50%, the signal spectral components are the least and concentrated in the part with lower frequency, and when the duty cycle is lower or higher than 50%, the spectral components increase and spread to the middle and high frequencies. The indoor test results indicate that changing the excitation signal parameters can also increase the detection range and depth to a certain extent without changing the sensor parameters. It can also reduce the detection blind area to a certain extent. Therefore, the conclusion of this article can solve the problem of large detection blind areas in transient electromagnetic detection, and the application field can also be extended from deep mineral detection to new areas, such as medium and shallow unexploded bombs, metal pipelines, and goafs.

In the complex indoor environment, geomagnetic matching is an effective way to realize indoor positioning of mobile robots. Aiming at the problem that the application of Particle Swarm Optimization (PSO) algorithm leads to the decline of geomagnetic matching accuracy, stability and convergence speed, an Iterated Local Search-Improved Particle Swarm Optimization (ILS-IPSO) algorithm is proposed. By analyzing the time-frequency characteristics and data distribution characteristics of geomagnetic survey data, geomagnetic data preprocessing and geomagnetic reference map construction are carried out. By introducing 3${\bm{\sigma }}$ contour Search domain constraint in the particle swarm optimization process, the weight factor, learning factors, step control factor of PSO algorithm are optimized, and finally the Local disturbance and search are implemented in combination with Iterated Local Search (ILS) algorithm. The experimental results show that the average matching accuracy error of ILS-IPSO is reduced to 0.0508 m, and the standard deviation of matching error is reduced to 0.0198m. Compared with PSO, Linear Dynamic time-varying Inertial Weight Particle Swarm Optimization algorithm (LDIW-PSO) and Cosine Decreasing Inertia Weight Particle Swarm Optimization algorithm (CDIW-PSO) algorithms, the average matching accuracy is increased by 94.72%, 92.37% and 87.98%, the standard deviation of matching error decreased by 87.13%, 83.26% and 89.81% respectively. The optimal fitness of ILS-IPSO algorithm is increased by 79.51%, 61.81% and 57.06%, and the iteration efficiency is increased by 69.23%, 55.56% and 33.33%, respectively. This method performs well in the accuracy, stability and convergence of geomagnetic positioning, and can be widely used in the field of indoor positioning.

A hi-speed rotation angular rate sensor based on an electromagnetic induction signal is proposed to provide a possibility of wide range measurement of high angular rates. An angular rate sensor is designed that works on the principle of electromagnetism (EM) induction. In addition to a zero-phase detection technique, this sensor uses the feedback principle of magnetic induction coils in response to a rotating magnetic field. It solves the challenge of designing an angular rate sensor that is suitable for both low and high rotating rates. The sensor was examined for angular rate measurement accuracy in simulation tests using a rotary table. The results show that it is capable of measuring angular rates ranging from 1 rps to 100 rps, with an error within 1.8‰ of the full scale (FS). The proposed sensor is suitable to measurement applications where the rotation angular rate is widely varied, and it contributes to design technology advancements of real-time sensors measuring angular acceleration, angular rate, and angular displacement of hi-speed rotary objects.

A magnetic induction-based angular rate measurement method is proposed to address the need for internal measurement of high-speed angular rate of carriers. This method relies on the rotational periodicity fed back by the magnetic field. Three coils aligned orthogonal one to another are employed as the feedback module that supplies the rotational periodicity information, the physical characteristic that contains the periodic signals, which in turn reflect the highly dynamic rotation of the carrier in its accelerating process. The periodic, instantaneous start point is extracted from the magnetic signal using zero-phase threshold technique, whereby the signal periodicity is established, enabling experimental measurement of the rotational angular rate of a high-speed rotation object. A semi-physical simulation was conducted at different speeds using a low maximum speed high-precision rotary table, and the results demonstrate that this measurement method is capable of measuring angular rate varying dynamically between 1 and 100 r/s, with a measurement error within 2 ⁰ / ₀₀ of the full scale. This method also provides a means for evaluating angular rate of other types of rotational movement.