Nauki Techniczne

Bulletin of the Polish Academy of Sciences Technical Sciences

Zawartość

Bulletin of the Polish Academy of Sciences Technical Sciences | 2024 | 72 | 2

Abstrakt

A global path-planning algorithm for robots is proposed based on the critical-node diffusion binary tree (CDBT), which solves the problems of large memory consumption, long computing time, and many path inflection points of the traditional methods. First of all, the concept of Quad-connected, Tri-connected, Bi-connected nodes, and critical nodes are defined, and the mathematical models of diverse types of nodes are established. Second, the CDBT algorithm is proposed, in which different planning directions are determined due to the critical node as the diffusion object. Furthermore, the optimization indices of several types of nodes are evaluated in real-time. Third, a path optimization algorithm based on reverse searching is designed, in which the redundant nodes are eliminated, and the constraints of the robot are considered to provide the final optimized path. Finally, on one hand, the proposed algorithm is compared with the A* and RRT methods in the ROS system, in which four types of indicators in the eight maps are analysed. On the other hand, an experiment with an actual robot is conducted based on the proposed algorithm. The simulation and experiment verify that the new method can reduce the number of nodes in the path and the planning time and is suitable for the motion constraints of an actual robot.
Przejdź do artykułu

Autorzy i Afiliacje

Zhiyong Yang
1
ORCID: ORCID
Lipeng Wang
1
ORCID: ORCID
Zejun Cao
1
Zhi Zhang
1
Zhuang Xu
1

  1. College of Intelligent Systems Science and Engineering, Harbin Engineering University, Harbin, 150001, China

Abstrakt

The purpose of the study was to evaluate selected mechanical properties and structural characteristics of samples manufactured using composite filament fabrication (CFF) technology from Onyx material, whichwas filled with continuous glass fiber. Selected mechanical properties were correlated with the density of the resulting composite to determine the specific strength of the fabricated parts. The test specimens were manufactured on a Mark Two Enterprise machine (Markforged, USA) using composite filament fabrication (CFF) technology. The material used was polyamide 6.6 with a 20% short carbon fiber content with the trade name Onyx. Continuous glass fiber was used to reinforce the fabrication. The density of the manufactured samples was determined using a hydrostatic method. Methanol was used as the liquid. By determining the density of the samples, it was possible to estimate through appropriate calculations what specific strength and specific modulus the obtained composites would have. Determination of tensile and flexural strengths was carried out in accordance with ISO 527-1:2012 and ISO 178:2003. Determination of the impact tensile strength of the samples was carried out in accordance with ISO 8256, the beams were tested using the A method. Due to the high impact tensile strength, two 1 mm notches with an angle of 45°were made on the specimens. The image of the sample structure obtained by the CFF method was recorded using a CT scanner. A thermogravimetric test (TG) of the Onyx matrix material was carried out. The samples were tested approximately 72 hours after fabrication. Filling the samples with continuous glass fiber above 50% leads to a slight increase in impact resistance. The density of the composite increased by only 16% relative to the reference samples, resulting in a 389% increase in the maximum average flexural strength. Despite significant discontinuities in the structure of the produced composite, it was possible to record an increase in tensile strength and Young’s modulus by 606% and 370%, respectively.
Przejdź do artykułu

Autorzy i Afiliacje

Dawid Marciniak
1
ORCID: ORCID
Dariusz Sykutera
1
ORCID: ORCID
Piotr Czyżewski
1

  1. Faculty of Mechanical Engineering, Department of Manufacturing Techniques, Bydgoszcz University of Science and Technology, Poland

Abstrakt

The article presents the assessment of the levels of radiated electromagnetic interference by commercial UAVs in the context of their popular use for various military tasks. The test was conducted in the frequency range from 30 MHz to 6 GHz, in an electromagnetically anechoic chamber, in accordance with the procedures provided for this type of checks. Apart from the control frequencies (which of course exceed the standards), it can be said that most of the tested UAVs using brushless motors do not exceed the emission levels specified by the military standard MIL-STD-461G. This opens the way to the use of COTS UAV as a carrier of electronic systems for the tasks of recognizing sources of radio signals in the investigated band.
Przejdź do artykułu

Autorzy i Afiliacje

Rafał Przesmycki
1
ORCID: ORCID
Jarosław Michalak
1
ORCID: ORCID

  1. Military University of Technology, ul. Gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland

Abstrakt

The objective of the research was to develop the Attitude Control System algorithm to be implemented in the Earth Observation Satellite System composed of leader-follower formation. The main task of the developed Attitude Control System is to execute attitude change manoeuvres required to point the axis of the image acquisition sensor to the fixed target on the Earth’s surface, while the satellite is within the segment of an orbit, where image acquisition is possible. Otherwise, the satellite maintains a nadir orientation. The control strategy is realized by defining the high-level operational modes and control laws to manage the attitude control actuators: magnetorquers used for desaturation of the reaction wheels and reaction wheels used for agile attitude variation. A six-degree-of-freedom satellite model was used to verify whether the developed Attitude Control System based on PID controllers for actuators performs attitude control in line with the requirements of an Earth Observation System. The simulations done for a variety of combinations of orbital parameters and surface target positions proved that the designed Attitude Control System fulfils the mission requirements with sufficient accuracy This high-level architecture supplemented by a more detailed control system model allowed proving efficient functionalities performance.
Przejdź do artykułu

Autorzy i Afiliacje

Janusz Narkiewicz
1
ORCID: ORCID
Szabolcs Grünvald
1
Mateusz Sochacki
1
ORCID: ORCID

  1. Faculty of Power and Aeronautical Engineering, Warsaw University of Technology, Nowowiejska 24, 00-665, Warsaw, Poland

Abstrakt

The current practice of reconstruction of oxidized turbine parts (due to hot corrosion) using arc welding methods facilitates restoration of the nominal shapes and dimensions, as well as other attributes and features. Intense development of 3D additive methods and techniques contributes to the repair/modification of different parts including gas turbine (GT) hardware. The article proves the viability of the concept of using a robotized additive arc welding metal active gas (MAG) process to repair and modify gas turbine diaphragms using different filler materials from the substrate. The industrialized robotic additive process (hybrid repair) shows that very good results were achieved if the diaphragm is cast of nickel-iron and the filler material for welding the passes is austenitic stainless steel (for instance 308 LSi). This is one of the novelties introduced to the repair process that was granted a patent (US11148235B2) and is already implemented in General Electric Service Centers.
Przejdź do artykułu

Autorzy i Afiliacje

Piotr Steckowicz
1
ORCID: ORCID
Paweł Pyrzanowski
2
ORCID: ORCID
Efe Bulut
3

  1. GE Power Sp. z o.o. – Oddział Engineering Innovation Center w Warszawie, Al. Krakowska 110/114, 02-256 Warsaw, Poland
  2. Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics, ul. Nowowiejska 24, 00-665 Warsaw, Poland
  3. GE Marmara Technology Center Müh. Hiz. Ltd. Sti. Tubitak-Mam Teknoloji Serbest Bolgesi, 41400, Gebze/Kocaeli, Turkey

Ta strona wykorzystuje pliki 'cookies'. Więcej informacji