The objective of this paper is to present an improved design of a wireless inductive sensor with novel compressive parts and its integration with a suitable mechanical device. The proposed system can be used as a seat occupancy detector with adjustable weight threshold. It consists of a sensor (inductor, steel springs and ferrite plate), an antenna, and a mechanical device for transferring the scaled weight to the sensor. The sensor is designed in such a way that the weight applied to its surface causes the built-in springs to compression and as a result, the reduction of the distance between the inductor and the ferrite plate which in turn changes in the sensor’s inductance and consequently the antenna-sensor resonant frequency, which is used as the electric output. The mechanical device which serves as a weight-converter has also been developed. The prototype of the system is fabricated and experimentally tested in order to confirm its functionality and performance. A three-segment linear characteristic is obtained with the following sensitivities: 0.9 MHz/kg for the weights of 0 - 20 kg, 1.86 MHz/kg for the weights of 20 - 40 kg and 0.19 MHz/kg for the weights of 40 - 50 kg. These results show that the developed system can detect the presence of weight and therefore, can be used for seat occupancy detection in a vehicle safety restraint and airbag systems. It can be also used as the indicator in the airbag safety restraint systems when the occupant’s weight exceeds the defined weight threshold for the airbag activation.

This paper shows the structure of a mechanical system with 9 DOFs for driving robot eyes, as well as the system’s ability to produce facial expressions. It consists of three subsystems which enable the motion of the eyeballs, eyelids, and eyebrows independently to the rest of the face. Due to its structure, the mechanical system of the eyeballs is able to reproduce all of the motions human eyes are capable of, which is an important condition for the realization of binocular function of the artificial robot eyes, as well as stereovision. From a kinematic standpoint, the mechanical systems of the eyeballs, eyelids, and eyebrows are highly capable of generating the movements of the human eye. The structure of a control system is proposed with the goal of realizing the desired motion of the output links of the mechanical systems. The success of the mechanical system is also rated on how well it enables the robot to generate non-verbal emotional content, which is why an experiment was conducted. Due to this, the face of the human-like robot MARKO was used, covered with a face mask to aid in focusing the participants on the eye region. The participants evaluated the efficiency of the robot’s non-verbal communication, with certain emotions achieving a high rate of recognition.

Displacement sensors play a key role in many applications. In this paper, an inductive structure is presented which changes its inductance with deformation, which serves as a measure of displacement. The structure itself is produced by ink-jet printing on a flexible polyimide foil, using a conductive silver-based nanoparticle ink. The foil is subsequently cut in such a way to allow for extending in a direction perpendicular to the foil plane. The resulting dependence of the inductance on the amount of extension is analyzed both in calculation and experimental measurement. Calculation is done using a variation of the Neumann formula adjusted to calculating self-inductance. A simple mathematical model of the structure deformation is introduced which proved to give results very close to the results obtained by measurement. The displacement range of the experimentally verified structure is up to 25 mm; however, the structure is expected to be scalable and therefore it should be possible to adapt it to various measurement ranges.

This article presents a flexible inductive sensor fabricated using additive 3-D printing technology. The sensor is designed in the form of a double-spiral structure and consists of two parts: the body and the lid. The designed parts of the sensor were made of a polylactic acid (PLA) filament. Inside the body, a conductive wire is embedded. The structure is thin enough to be elastic and, therefore, it is suitable for displacement or force measurement. The structure can be easily extended, which causes the inductive coupling between the spiral traces to decrease, lowering in turn its self-inductance. When it is used as a sensor, self-inductance serves as the measure of displacement. Displacement measurements up to 26 mm with 2 mm steps were made using the $LCZ$ meter HP4227A. Three sensor structures with an outer dimension of 4.5 cm and a varying number of spiral turns (3/4, 5/4, and 7/4) were produced and examined. The change in inductance with displacement for all three structures was modeled and analyzed. The numerical simulation was compared with the obtained experimental results, and good agreement was found (the difference is below 10%). The measurement results confirmed the efficiency of the designed sensor. Additionally, measuring respiratory rate is proposed as one of its potential applications in medicine.

This paper presents an application of 3D printing technology for the production of a flexible inductive displacement sensor. In order to achieve wireless measurements, the sensor is designed in the form of an Archimedean spiral. An additional more complex structure consisting of two spirals was also examined. When displacement is applied to the spiral center, an increase in the distance between the adjacent turns of the spiral is achieved. As a result, there will be a decrease in inductance and a consequent change in the sensor’s self-resonant frequency. The change in resonant frequency is detected using an external coil (antenna) adapted to the sensor. The sensors are read by determining their phase-dip minimum or phase-peak maximum. This way the resonant frequency vs. displacement characteristics are obtained. The displacement measurement range is up to 30 mm. The calculated sensitivity of the proposed single and double sensor spiral systems are 1.54 MHz/mm and 0.19 MHz/mm respectively.

In the Master Academic Studies of Power, Electronics and Telecommunication Engineering, at the Faculty of Technical Sciences, University of Novi Sad, Electromagnetic Interference and Electromagnetic Compatibility in Electronics is a subject students can choose. Within this course, students gain theoretical and practical knowledge in this field. The most economical way of reducing electromagnetic interference (EMI) is to use appropriate methods during the system design phase. In this course the students learn to design electronic circuits and systems immune to EMI, to implement, test, and apply EMI protection components (such as ferrite EMI suppressors, varistors, etc.), to design good PCB layouts, and use proper grounding and shielding to meet EMC standards (electromagnetic compatibility standards). In this paper, the structure of the course is presented. Additionally, a few examples are shown of the simulation tasks and laboratory exercises, giving an insight into the laboratory equipment used for the course.