DEMYDENKO, S. Detection of absolute position of object based on relative change of phase [online]. Brno: Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií. 2023.
The student Serhii Demydenko has written his bachelor thesis on the design of a system for absolute position detection of objects using phase change detection of the received radio frequency signal. The thesis is in the field of automation and robotics. The text of the thesis is 56 pages long including appendices, which is the usual length for a bachelor thesis. The thesis is logically divided into 4 parts, supplemented by a list of references and appendices. The student used the recommended template, the thesis is written in English. I have to appreciate the student's independence in preparing the whole thesis. He chose the topic himself, after initial research in chapter 1 he proposed his own method of detecting the position of an object equipped with a transmitter, which is closer to the detector than the wavelength of the signal used. The author presents a theoretical analysis of the proposed method, proceeding from a basic arrangement with two receivers placed at a defined mutual distance, to an arrangement with two quads of receivers to determine the object's position unambiguously. He chose 433 MHz as the appropriate transmitter frequency, as this is a commonly used value in communication modules and is therefore readily available, in addition to being in a free usable frequency band. The proposed method is fully described in Chapter 2, including implementation in a Matlab script in which the author performed simulations to verify the functionality of the design. Then, in Chapter 3, he discusses the practical verification through laboratory experiments, as well as the analysis of the effect of signal reflections and used antennas type. He also proposes a theoretical arrangement of the receiving beacon as a basic detector cell with six antennas and three phase detectors. The student worked practically independently on the thesis and showed creative inventiveness. I consider the objectives of the thesis to have been met and the proposed method to be applicable for the intended purpose of object position detection. The submitted text meets the requirements for a bachelor thesis, I recommend it for defense with a grade of B, 83 pts.
The presented bachelor thesis of the student Serhii Demydenko deals with the theoretical design and experimental verification of the determination of the absolute position of the tracked object based on the measurement of the phase of signals from the detection antennas. The student studied the available literature and proposed several variants of Matlab scripts to verify the proposed conguration. For testing he used phase measurements using an oscilloscope, but here it is not clear whether he chose a suitable mode, for example averaging, so that the phase reading is not burdened by noise (he gives a measured variance of up to 5°). He also tested the effect of signal reflections in the test room, here it would be appropriate to make a reference measurement in a reflection-free chamber available at the supervisor's workplace. As for the proposed system, it is not clear whether the amplifiers will be used directly at the antenna, which would be preferable, or via a patch cable, which introduces unwanted uncertainties into the measurements. The measurement chain will certainly introduce additional phase shift in the input signals, so it would be good to account for it and correct for it. At the input of the AD8302, it would be advisable to keep the level of both inputs constant for maximum measurement accuracy, the input signal level may vary according to the position of the transmitter relative to the antennas. The required phase measurement accuracy is not considered. The AD8302 has the largest phase measurement error around 0° and 180°, so it is always advantageous to include a possible switchable phase cell in the measurement channel.
eVSKP id 152617