Magnetic position and speed sensors are rugged and durable. While DC magnetic sensors use permanent magnets as a field source and usually have only mm or cm range, inductive sensors use electromagnetic induction and they may work up to a distance of 20 m. Eddy current inductive sensors equipped with magnetoresistive sensors instead of inductive coils can operate at low frequencies, allowing detection through a conductive wall. In this paper, we make an overview of existing systems and we present new results in eddy current velocity and position measurements. We also present several types of inductive position sensors developed in our laboratories for industrial applications in pneumatic and hydraulic cylinders, underground drilling, large mining machines, and for detecting ferromagnetic objects on conveyors. While the most precise inductive position sensors have a resolution of 10 nm and linearity of 0.2%, precision requirements on the industrial sensors which we develop are less demanding, but they should have large working distance and large resistance to environmental conditions and interference.

The magnetic field created by technical devices is a source of information. This information could be used in contactless diagnostics and predictive maintenance or for resolving problems along with standard NDT (nondestructive testing) methods, especially if we consider large, slow-speed devices, such as electromotors, transmissions, or generators. Identification of causalities of device failure processes with near magnetic field is one of the suitable NDT methods improving sustainability of systems. The measurements presented in the article were performed with the VEMA 04 fluxgate vector magnetometer with the DC-250 Hz bandwidth and 2 nT sensitivity. Postprocessing of the results was performed in the means of standard methods of discrete Fourier Transform, spectrogram creation and Wavelet Transform. The article presents data gathered during the measurement of a pair of extraction fans with power of 140 kW each and maximum revolutions up to 740 rev/min controlled by frequency converters and a single semi-Kaplan water power plant with 400 kW peak power at 1005 rev/min maximum generator speed. The measurements were performed before and after repairs of one of the ventilators in the ventilation system at 60% and 100% of maximal output power. The rotating magnetic fields of the fan electromotor stator, fan rotor revolutions, rotor slip frequency and ball-bearing frequencies were identified in frequency spectrums in the distance of 700 mm from fan electromotor axis in both cases. During the measurements on the semi-Kaplan turbine, the changes in states of mechanical and electrical components of the machine were monitored in the magnetic fields with increase of the power in the range of 0–95%, before and after phasing to the electrical grid. Standard processing methods, Discrete Fourier Transform, spectrograms and Discrete Wavelet Transform were used. In the spectrograms of the measured magnetic fields, the 1st–4th harmonics of the turbine shaft, generator shaft and also their side frequencies were identified. Significant changes of magnetic fields in time were identified in the area of 60–95% power. With the help of the Wavelet, transform intervals were identified where it is desirable to operate the turbine. The analyses of magnetic fields measurements performed on the power plant were compared with vibro-diagnostic principles.

The development of non-destructive methods for material testing and diagnostics has been, in the last few decades, focused mainly on optical, infrared, thermography, ultrasonic, acoustic or X-ray principles. This article deals with the possibility of adaptation of magnetic sensors for the diagnostics of aircraft structures. The developed sensors are based on the enhanced induction method, allowing contactless diagnostics of the material structure. In the role of the sensing element, amorphous magnetic microwires were used. Thanks to their dimensions, microwires can either be placed on the material surface or be embedded directly into the composite material without structural violations. In the article, the measurement principles of the developed microwire-based tensile stress sensors, together with the experimental measurements with the sensors originally tested in the aircraft wing, are presented.

This article deals with quadcopter modeling using a system for the measurement of unmanned aerial vehicle (UAV) parameters. UAVs are often equipped with various measurement devices and equipment for measurement, which significantly affects their weight. The currently available technical solutions and inventions do not allow corrections to be made to the on-board control electronics settings without the need to perform a test flight, or without the need to create complex and time-consuming mathematical models of the unmanned aerial vehicle; therefore, it is desirable to create a new method for modeling the characteristics of an UAV based on static laboratory measurements. The goal of this paper is to create a dynamic model of a quadcopter that will be adapted to a system for measuring UAV parameters, specifically the thrust of individual motors, which will be the next step to creating a new method for modeling UAV characteristics. This method can be used in the future for tuning flight control algorithms, based on static laboratory measurements.

The presented article briefly explains the history and the success of applied magnetism, which has been the main focus of the research and development scientist group originally seated at Slovak Air Force Academy of Milan Rastislav Štefánik in Košice. The group has focused on measuring magnetic fields since 1982 when they developed the first digital magnetometer in former Czechoslovakia. Knowledge gathered during the development of the magnetometer and its further use for research activities led to wide industrial applications of magnetism after 1990. The industrial version of the magnetometer has been developed for the mining and steel production industry. The scope of research has been spread again and topics such as non-destructive diagnostics of machines, non-destructive archeological prospection, or magnetic navigation have been successfully solved. In 2014, the skCUBE project was started and the development of the first Slovak satellite began. Most of the knowledge in the field of applied magnetism has been used in the development of magnetic actuators and calibration methods for onboard magnetometers. The success of this work leads to cooperation on the following satellite mission GRBAlpha. Nowadays, the research is continuing in the project consortium focused on the scaling of the magnetic actuator for satellites in the weight category from 70 to 500 kg. The article explains the results of the development of satellite actuators. Laboratory measurements show that the efficiency of the actuator is almost doubled with respect to the standard commercial products in the CubeSat category. Based on this research the actuator can provide higher performance within the same volume, weight, and input power, or provide the same performance and save volume, weight, and input power.