This paper relates to a fuzzy flight control system in spot hovering for a single-rotor helicopter PZL Kania. The model of the fuzzy control system was developed on the basis of computer simulation experiments done by the expert's analysis (pilot's knowledge). The helicopter's mathematical model and its fuzzy flight control system were simulated using Matlab software package. In a series of numerous computer simulations the operation of the fuzzy control system was investigated and the system itself was tuned up. Simulation tests have been performed for the helicopter both in fixed hovering, and in hovering with disturbances. Disturbances were related to a gust of wind or to an accidental motion of one of the rudders. Obtained results give the good promise for building the Web simulator.

The paper presents the problem of design and simulation of a high-speed wide-band high-resolution analog-to-digital (ADC) converter working in a bandpass scenario. Such converters play a crucial role in software-defined radio and in cognitive radio technology. One way to circumvent the limits of today’s ADC technologies is to split the analog input signal into multiple components and then sample them with ADCs in parallel. The two main split approaches, time interleaved and frequency splitting, can be modeled using a filter bank paradigm, where each of these two architectures requires a specific analysis for its design. In this research, the frequency splitting approach was implemented with the use of a hybrid filter bank ADC, which requires an output digital filter bank perfectly matched to the input analog filter bank. To achieve this end, an analog transfer function, together with an assumption of strictly band-limited input signal, has been used to design the digital filter bank so far. In contrast, the author proposes dropping the band-limit assumption and shows that the out-of-band input signal has to be taken into account when designing a hybrid filter bank.

Rapid development of many scientific and technical disciplines, especially in material science and material engineering increases a demand for quick, accurate and cheap techniques of materials investigations. The EPR spectroscopy meets these requirements and it is used in many fields of science including biology, chemistry and physics. For proper work, the EPR spectrometer needs a microwave source, which are reviewed in this paper. Vacuum tubes as well as semiconductor generators are presented such as magnetron, klystron, traveling wave tube, backward wave oscillator, orotron, gyrotron, Gunn and IMPATT diodes. In this paper main advantages of gyrotron usage, such as stability and an increased spectral resolution in application to EPR spectroscopy is discussed. The most promising and reliable microwave source is suggested.

This paper proposes the use of close-distance optical flow measurements to enhance the Extended Kalman Filter (EKF) position and velocity estimation accuracy of Unmanned Aerial Vehicle (UAV) with the use of existing infrastructure in a GPS-denied environment. The scenario assumed in this project involves a UAV navigating through a mine shaft with a stationary central steel cable that passes through the shaft's center. The UAV has a special design with a hole in the center that allows it to fly up and down while keeping the central cable in its geometric center. The UAV is equipped with a camera facing parallel to the cable at a close and constant distance. Using optical flow algorithms, we can estimate the vertical velocity of the UAV. Using the EKF filter, we aim to integrate these velocity measurements with existing measurements from the Inertial Measurement Unit (IMU), magnetometer, and barometer, to improve the accuracy of the UAV's vertical velocity and height measurements.

This article investigates the causes of occasional flight instability observed in Unmanned Aerial Vehicles (UAVs). The issue manifests as unexpected oscillations that can lead to emergency landings. The analysis focuses on delays in the Extended Kalman Filter (EKF) algorithm used to estimate the drone’s attitude, position, and velocity. These delays disrupt the flight stabilization process. The research identifies two potential causes for the delays. First cause is magnetic field distrurbances created by UAV motors and external magnetic fields (e.g., power lines) that can interfere with magnetometer readings, leading to extended EKF calculations. Second cause is EKF fusion step implementation of the PX4-ECL library combining magnetometer data with other sensor measurements, which can become computionally expensive, especially when dealing with inconsistent magnetic field readings. This can significantly increase EKF processing time. The authors propose a solution of moving the magnetic field estimation calculations to a separate, lower-priority thread. This would prevent them from blocking the main EKF loop and causing delays. The implemented monitoring techniques allow for continuous observation of the real-time operating system’s behavior. Since addressing the identified issues, no significant problems have been encountered during flights. However, ongoing monitoring is crucial due to the infrequent and unpredictable nature of the disturbances.

The aim of the paper is to present a simplified implementation of quadrature phase shift keying (QPSK) based underwater communication system. The presented solution addresses the problem of developing inexpensive, compact ultrasound modems able to be mounted on underwater robots. Simplifications introduced into the modulation and demodulation of QPSK signals do not disturb any parameter of the data link. The paper indicates that it is possible to realize modulation and demodulation on a simple microcontroller. Many hints are given on how to use hardware blocks embedded in a microcontroller, such as ADC, DMA, timers, etc. Experiments performed with the prototype modems allow to reach 4 kbps data rate on a distance of about 18 m.