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Wyświetlanie 1-7 z 7
Tytuł:
Epistemocentryzm jako epistemologiczna przeszkoda nauk społecznych
Epistemocentrism as an Epistemological Obstacle in the Social Sciences
Autorzy:
Kuszyk-Bytniewska, Mariola
Powiązania:
https://bibliotekanauki.pl/articles/577326.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
BOURDIEU
EPISTEMOCENTRISM
EPISTEMOLOGICAL OBSTACLE
SOCIAL SCIENCES
Opis:
Rationality, intersubjectivity, and objectivity have been conceived as primary epistemological categories from the begining of modern epoch. They characterize knowledge or subjects of knowledge, or even their activity - cognition. Epistemocentrism - in P. Bourdieu view typical to modern thinking - and supporting it epistemological fundamentalism are nothing else but limitation of the meaning of these categories. In the bygone times, epistemocentrism was useful, but now is a simply anachronism in the face of modern roles of knowledge in societies and in the face of growing progress of social sciences. Today, science and its contribution in the social worlds are not the same as once. Therefore, the need arises for revision of epistemocentrism as well as for the fulfillment of the 'epistemological gap' which emerged from collapse of epistemological fundamentalism. I think that there is a room for the new 'philosophical partition of reality' emancipated from Cartesian despotism of ego cogito and recovering intuitional insights in the social life of the ancient thinkers as Aristotle. In the paper, I concentrate on thesis that epistemocentrism is an epistemological obstacle in the social sciences and source of their crises.
Źródło:
Zagadnienia Naukoznawstwa; 2011, 47, 2(188); 165-182
0044-1619
Pojawia się w:
Zagadnienia Naukoznawstwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An embedded beamformer for a PID-based trajectory sensing for an autonomous vehicle
Autorzy:
Mvemba, P. K.
Lay-Ekuakille, A.
Kidiamboko, S.
Rahman, M. Z. U.
Powiązania:
https://bibliotekanauki.pl/articles/221802.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
autonomous vehicle
beamforming
trajectory follower
ultrasonic obstacle detector
measurement
sensors
Opis:
Beamforming is an advanced signal processing technique used in sensor arrays for directional signal transmission or reception. The paper deals with a system based on an ultrasound transmitter and an array of receivers, to determine the distance to an obstacle by measuring the time of flight and - using the phase beamforming technique to process the output signals of receivers for finding the direction from which the reflected signal is received - locates the obstacle. The embedded beam-former interacts with a PID-based line follower robot to improve performance of the line follower navigation algorithm by detecting and avoiding obstacles. The PID (proportional-integral-derivative) algorithm is also typically used to control industrial processes. It calculates the difference between a measured value and a desired set of points, then attempts to minimize the error by adjusting the output. The overall navigation system combines a PID-based trajectory follower with a spatial-temporal filter (beamformer) that uses the output of an array of sensors to extract signals received from an obstacle in a particular direction in order to guide an autonomous vehicle or a robot along a safe path.
Źródło:
Metrology and Measurement Systems; 2018, 25, 3; 561-575
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of slim obstacle geometry on the flow and heat transfer in microchannels
Autorzy:
Kmiotek, M.
Kucaba-Piętal, A.
Powiązania:
https://bibliotekanauki.pl/articles/200994.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
microchannels
obstacle
finite element method
mikrokanały
przeszkody
metoda elementów skończonych
Opis:
This paper presents a computational study on hydrodynamic and heat transfer characteristics of the laminar flow inside a rectangular 2D microchannel of height H, which includes a slim micro obstacle of height h and width w placed on the lower wall of the channel. The Reynolds number varies between 20 and 200. Three different values of height h and two different shapes of the slim obstacles: triangular and rectangular one, are considered. Thus, a total of 24 geometrical configurations of fluid flow are analyzed. Fluid flow equations are solved using the commercial CFD package of ADINA R&D, Inc. 9.1. Detailed analysis of the fluid velocity field and streamlines is carried out to investigate the flows in recirculation zone behind the obstacle. Results obtained show that the rectangular obstacle caused larger vortex formation in fluid flow. For flows with larger value of the (h/H) ratio, an increase in the value of loss coefficient factors is observed. Meanwhile, the increased Reynolds number causes the vortex zone behind the rectangular obstacle to be larger than behind the triangular one.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2018, 66, 2; 111-118
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The obstacle vector field (OVF) method for collision-free trajectory planning of free-floating space manipulator
Autorzy:
Rybus, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/2173652.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
space robotics
obstacle avoidance
obstacle vector field
free-floating system
on-orbit servicing
robotyka kosmiczna
unikanie przeszkód
pole wektora przeszkód
system swobodnie pływający
serwis orbitalny
Opis:
Manipulators mounted on small satellites will be used to perform on-orbit servicing, removal of space debris, and assembly of large orbital structures. During such operations, the manipulator must avoid collisions with the target object or the elements of the assembled structure. Planning of the manipulator trajectory is one of the major challenges for the proposed missions because the motion of the manipulator influences the position and orientation of the satellite. Thus, the dynamic equations of motion must be used during trajectory planning. Methods developed for fixed-base manipulators working on Earth cannot be directly applied. In this paper, we propose a new obstacle vector field (OVF) method for collision-free trajectory planning of a manipulator mounted on a free-floating satellite. The OVF method is based on a vector field that surrounds the obstacles and generates virtual forces that drive the manipulator around the obstacles. The OVF method is compared with the classical artificial potential field (APF) method and the rapidly exploring random trees (RRT) method. In the presented examples the trajectory planning problem is solved for a planar case in which the satellite is equipped with a 2 DoF manipulator. It is shown that the OVF method is more efficient than the APF method, i.e., it allows us to solve the trajectory planning problem in some of the cases, in which the APF method is unsuccessful. The time required to find the solution with the use of the OVF method is shorter than the time needed by the APF and the RRT method.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 2; art. no. e140691
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Energy-efficient walking over irregular terrain: a case of hexapod robot
Autorzy:
Luneckas, Mindaugas
Luneckas, Tomas
Udris, Dainius
Plonis, Darius
Maskeliunas, Rytis
Damasevicius, Robertas
Powiązania:
https://bibliotekanauki.pl/articles/220953.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hexapod walking robot
irregular terrain
obstacle avoidance
energy consumption
leg trajectory optimization
Opis:
Adaptive locomotion over difficult or irregular terrain is considered as a superiority feature of walking robots over wheeled or tracked machines. However, safe foot positioning, body posture and stability, correct leg trajectory, and efficient path planning are a necessity for legged robots to overcome a variety of possible terrains and obstacles. Without these properties, any walking machine becomes useless. Energy consumption is one of the major problems for robots with a large number of Degrees of Freedom (DoF). When considering a path plan or movement parameters such as speed, step length or step height, it is important to choose the most suitable variables to sustain long battery life and to reach the objective or complete the task successfully. We change the settings of a hexapod robot leg trajectory for overcoming small terrain irregularities by optimizing consumed energy and leg trajectory during each leg transfer. The trajectory settings are implemented as a part of hexapod robot simulation model and tested through series of experiments with various terrains of differing complexity and obstacles of various sizes. Our results show that the proposed energy-efficient trajectory transformation is an effective method for minimizing energy consumption and improving overall performance of a walking robot.
Źródło:
Metrology and Measurement Systems; 2019, 26, 4; 645-660
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Navigation of autonomous mobile robot using different activation functions of wavelet neural network
Autorzy:
Panigrahi, P. K.
Ghosh, S.
Parhi, D. R.
Powiązania:
https://bibliotekanauki.pl/articles/229613.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
autonomous mobile robot
activation functions
obstacle avoidance
path planning
wavelet neural network
Opis:
An autonomous mobile robot is a robot which can move and act autonomously without the help of human assistance. Navigation problem of mobile robot in unknown environment is an interesting research area. This is a problem of deducing a path for the robot from its initial position to a given goal position without collision with the obstacles. Different methods such as fuzzy logic, neural networks etc. are used to find collision free path for mobile robot. This paper examines behavior of path planning of mobile robot using three activation functions of wavelet neural network i.e. Mexican Hat, Gaussian and Morlet wavelet functions by MATLAB. The simulation result shows that WNN has faster learning speed with respect to traditional artificial neural network.
Źródło:
Archives of Control Sciences; 2015, 25, 1; 21-34
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Obstacle avoidance method of autonomous vehicle based on fusion improved A*APF algorithm
Autorzy:
Qian, Yubin
Sun, Hongtao
Feng, Song
Powiązania:
https://bibliotekanauki.pl/articles/2204535.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
obstacle avoidance
path planning
fuzzy control
tracking control
unikanie przeszkód
planowanie ścieżki
kontroler rozmyty
kontroler śledzenia
Opis:
This paper proposes an autonomous obstacle avoidance method combining improved A-star (A*) and improved artificial potential field (APF) to solve the planning and tracking problems of autonomous vehicles in a road environment. The A*APF algorithm to perform path planning tasks, and based on the longitudinal braking distance model, a dynamically changing obstacle influence range is designed. When there is no obstacle affecting the controlled vehicle, the improved A* algorithm with angle constraint combined with steering cost can quickly generate the optimal route and reduce turning points. If the controlled vehicle enters the influence domain of obstacle, the improved artificial potential field algorithm will generate lane changing paths and optimize the local optimal locations based on simulated annealing. Pondering the influence of surrounding participants, the four-mode obstacle avoidance process is established, and the corresponding safe distance condition is analyzed. A particular index is introduced to comprehensively evaluate speed, risk warning, and safe distance factors, so the proposed method is designed based on the fuzzy control theory. In the tracking task, a model predictive controller in the light of the kinematics model is devised to make the longitudinal and lateral process of lane changing meet comfort requirements, generating a feasible autonomous lane-change path. Finally, the simulation was performed in the Matlab/Simulink and Carsim combined environment. The proposed fusion path generation algorithm can overcome the shortcomings of the traditional single method and better adapt to the dynamic environment. The feasibility of the obstacle avoidance algorithm is verified in the three-lane simulation scenario to meet safety and comfort requirements.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2023, 71, 2; art. no. e144624
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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