Advanced Magnetic Materials for Aeronautics

In the field of magnetic sensors, magnetic microwires with positive magnetostriction are the materials of the future. Their mechanical and magnetic properties render them ideal materials for applications in aeronautics. A single microwire with a 40 μm diameter and a length of 10 mm is capable of capturing information about tensile stresses, magnetic fields, temperature and distance. This information is carried by a parameter called the Switching Field, HSW, which is specific for different types of microwire. Numerous physical qualities affect the HSW and through sensing of HSW, these qualities may be quantified. (A number of physical qualities affecting HSW can be sensed and quantified by means of a contactless induction method.) What distinguishes the system developed by the present authors from other measuring systems based on magnetic microwires is the positioning of a microwire outside the coil system. Thanks to this improvement it is possible to use microwires embedded directly in the construction material. Small dimensions microwires do not damage the structure of the construction material. The absence of a galvanic connection makes this technology even more interesting compared with traditional forge gauges. Offering the possibility of the simultaneous measuring of four parameters, this technology can be used in a wide range of aviation applications. Measurements of an external magnetic field can be used for the navigation and stabilization of an aerial vehicle. Tensile stress and distance measuring can be helpful to understand some processes occurring under the surface of the construction material and also to perform fatigue monitoring or structure load monitoring. Another big advantage of magnetic microwires is the low price. Just 1 gram of base material is sufficient to prepare about 40 km of microwire. All these features combine to offer us a material ideal for Smart Sensors, possibly available for use in the near future

Possibile Applications of Magnetic Microwires in Aviation

Magnetic microwires have been rediscovered due to a number of the unusual magnetic properties and their potential applications. The paper concerns glass-coated magnetic microwires composed of a ferromagnetic metallic core with a diameter of 0.6 – 30 μm and of a glass coat with a thickness of 2 – 20 μm. The fabrication process and magnetic properties of these microwires are described. Due to their unique properties microwires can be used as a sensing element of sensors. Microwire-based sensors can be used in a wide range of aviation applications as magnetic field sensors, tensile stress sensors or temperature sensors. The main advantages of microwire-based sensors are associated with their small dimensions and weight, which play a very important role in aviation

Possibile Applications of Magnetic Microwires in Aviation

Magnetic microwires have been rediscovered due to a number of the unusual magnetic properties and their potential applications. The paper concerns glass-coated magnetic microwires composed of a ferromagnetic metallic core with a diameter of 0.6 – 30 μm and of a glass coat with a thickness of 2 – 20 μm. The fabrication process and magnetic properties of these microwires are described. Due to their unique properties microwires can be used as a sensing element of sensors. Microwire-based sensors can be used in a wide range of aviation applications as magnetic field sensors, tensile stress sensors or temperature sensors. The main advantages of microwire-based sensors are associated with their small dimensions and weight, which play a very important role in aviation

Estimation of Multichannel Magnetometer Noise Floor in Ordinary Laboratory Conditions

The article deals with the method of the inherent noise estimation in each channel of a four channel relax-type magnetometer in general laboratory conditions. The day-long development of ambient magnetic field has been recorded and then the data were processed by correlation methods to separate inherent noises of the channels from ambient noise in the statistically best times. The method is applicable for noise estimation of any multi-channel sensoric system and also for the separation of deterministic and stochastic components of signals

Noise Characteristics of Microwire Magnetometer

Current trends in modernization and miniaturization of ferroprobe sensors lead to replacement of amorphous ribbon cores with magnetic microwires. The miniaturization often causes degradation in the parameters of sensors, so, considering measurement of weak magnetic fields, it is necessary to explore noise parameters, temperature drift and stability of the magnetometer output value. The article deals with analysis of microwire sensor noise characteristics based on the experimental data processing. Using one second periodograms, the linear spectral density was processed. Obtained data are compared with corresponding parameters of a relax-type ferroprobe magnetometer

Calibration of Magnetometer for Small Satellites Using Neural Network

The article presents the scalar calibration method that uses a neural network for the determination of parameters of the inverse model of the vector magnetometer. Utilization of the one layered, feed-forward neural network with the back propagation algorithm has suppressed the systematic errors of the vector magnetometers, namely the multiplicative, additive, orthogonality and linearity errors. Methodology shown in the article was designed and used for a pre-flight calibration of the magnetometer used in the first Slovak satellite skCUBE, where the magnetometer performs stabilization and navigation tasks. The experiment was performed in a 3D Helmholtz coil system, where the Earth magnetic field was suppressed and at the same time the stimulation field was created. Suppression of the Earth magnetic field was achieved by special positioning of the satellite. Honeywell HMC 5883L was used for the verification of the methodology

New Generation of Magnetic Relaxation Sensors Based on the Melt-Spun FeCoBCu Alloys

We report on the development of new generation of magnetic relaxation sensors based on soft magnetic melt-spun ribbons with the composition $Fe_{63}Co_{21}B_{15}Cu$. The as-quenched amorphous alloy was subjected to thermomagnetic heat treatment in order to obtain sensor cores with optimized magnetic properties. The relaxation characteristics obtained for these cores by employing upgraded sensor electronics were compared to those based on the model simulations using Matlab-Simulink environment. The operational field range of new developed sensor core reached 300 μT within the frequency band 0-500 Hz, i.e. it is markedly extended as compared to the currently used cores based on the commercial VAC 25X material while keeping the similar sensitivity

Noise Analysis of Magnetic Sensors Using Allan Variance

The article deals with the noise analysis of magnetic sensors using Allan variance. In comparison with the standard variance, based on the variations around the average value, Allan variance provides a measure of the behavior of the variability of a quantity as it is averaged over different measurement time periods, which results in a better convergence and the possibility to distinguish types of noise directly. A significant advantage of this method is that there is no need of any transformations and according to the IEEE recommendation the Allan variance approach is the preferred method for stochastic error identification and the noise type determination in inertial sensors (accelerometers and gyroscopes). Considering that magnetic sensors become even more often a part of inertial measurements units, the goal of this article is to prove that the method using the Allan variance analysis can be very successfully applied also for noise analysis in magnetic sensors

Advanced Method for Magnetic Microwires Noise Specification

The article points to the effects of the ambient noise and its possible influences on quantification of the inherent switching field noise of magnetic microwires. Based on the observed effects, an advanced methodology was developed to quantify the impact of the ambient noise. During measurements a multi-channel system with applied correlation methods was used. The proposed method determines the percentage contribution of the ambient noise deviation to the magnetic microwires switching field noise