Experimental Measurement of a UAV Propeller\u27s Thrust

At present, there are several types of propellers in the field of the use of Unmanned Aerial Vehicles (UAVs) with unknown parameters, where it is necessary to provide information about their thrust, current consumption and maximal rotational speed (RPM). Commonly used methods for measurement of a propeller\u27s thrust are mostly based on the usage of a single purpose system, on short measurements without data storage or on inaccurate sensors. The goal of this article is to develop a universal experimental measuring system for more accurate measurement of propeller\u27s parameters (thrust, current consumption, maximal RPM). For more accurate measurement, the battery voltage, temperature and humidity of the environment were also measured. To acquire, measure and store the data safely on a micro SD card, a processing circuit based on an ATmega2560 microcontroller was developed. This innovative approach allowed to analyse the behaviour of the propeller and to measure the dependencies of the RPM on pulse width, of the current on RPM and of the thrust on RPM at different input conditions. The measurements have shown that the dependencies can be approximated by cubic functions. The mathematical description allows predicting the behaviour of the propeller in unmeasurable conditions

Effect of Bismuth and Silver on the Corrosion Behavior of Lead-free Solders in 3.5 wt% NaCl Solution

Electroanalytical tests were carried out to investigate the corrosion behavior of various lead-free solder alloys in 3.5 wt% NaCl bulk solution under room temperature. Scanning electron microscope (SEM) method was applied to investigate the corroded surface structure and corrosion depth using cross-sectional samples. Furthermore, energy dispersive spectroscopy (EDS) method was also applied to identify the chemical elemental composition of the corrosion products of the solders. The results showed that the bismuth and silver bearing solders have lower corrosion resistance compared to other lead-free solders and to the widely used SAC305 as well. The different corrosion resistance was explained by the different silver and bismuth content and volume of the corrosion products, which can lead back to the differences of the original alloying components. This study is highlighted that the bismuth and silver content may pose a relative high corrosion risk related to lead-free solder alloys used in electronics

The effect of the number of inference rules of a fuzzy controller on the quality of control of a mobile robot

The application of intelligent control algorithms in the field of autonomous mobile robotics enables effective control of mobile robots with a minimal possible error. At present, most of commonly used systems to control an autonomous mobile robot are, however, too complicated to design. Our goal was to design a fuzzy controller with an optimal number of inference rules in a way to achieve the best possible level of quality of mobile robot control. The proposed controller was implemented in the mobile robot EN20, where the time of regulation and the absolute and the quadratic control surface were used to evaluate quality parameters. The analysis of the quality of control was performed with the use of a fuzzy controller with 9, 25 and 49 inference rules. We found from the results of modelling that the greatest influence on the quality of control of a mathematical model of the mobile robot had the number of inference rules of the fuzzy controller. Mathematical and graphical dependence of the quality of control on the number of inference rules was calculated from the parameters of the quality of control. The results of the research are equations of the curves of the individual parameters of control of quality, which show that for the control of the autonomous mobile robot EN 20, that the optimal fuzzy controller has 49 inference rules, triangular functions of the pertinence of individual linguistic values and it is defuzzificated by Centroid method