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1
Content available Obstacle avoidance method of autonomous vehicle based on fusion improved A*APF algorithm
Qian Yubin, Sun Hongtao, Feng Song
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2023
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Vol. 71, nr 2
art. no. e144624
EN
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.
2
Content available The obstacle vector field (OVF) method for collision-free trajectory planning of free-floating space manipulator
Rybus Tomasz
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2022
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Vol. 70, nr 2
art. no. e140691
EN
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.
3
Content available remote Analysis of methods and control systems of unmanned platforms
Adamski Mirosław, Żyluk Andrzej, Chodnicki Marcin
Journal of KONBiN
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2021
|
Vol. 51, iss. 4
143--156
EN
The key aspect affecting the safety of routing and the unmanned platform mission execution is the autonomy of control systems. To achieve the mission goal, control algorithms supported by advanced sensors have to estimate the obstacle location. Moreover, it is needed to identify potential obstacles, as well as algorithms for trajectory planning in two or three dimensions space. The use of these algorithms allows to create an intelligent object that performs tasks in difficult conditions in which communication between the platform and the operator is constricted. The article mainly focuses on unmanned aerial vehicle (UAV) control systems.
PL
Kluczowym aspektem mającym wpływ na bezpieczeństwo trasowania oraz realizacji misji platformy bezzałogowej jest autonomia systemów sterowania. Z tego względu algorytmy sterowania wspierane przez zaawansowane czujniki muszą oszacować lokalizację przeszkody. Poza tym, należy identyfikować potencjalne przeszkody oraz algorytmy dotyczące planowania trajektorii w dwóch lub trzech wymiarach przestrzennych. Zastosowanie wyżej wspomnianych algorytmów umożliwia stworzenie inteligentnego obiektu wykonującego zadania w trudnych warunkach, podczas których komunikacja pomiędzy platformą a operatorem jest ograniczona. Artykuł opisuje głównie systemy sterujące bezzałogowych statków powietrznych (BSP).
4
Content available Motion planning of planar and redundant underwater serial link manipulator based on minimization of energy consumption
Kumar Virendra, Sen Soumen, Roy Shibendu Shekhar
Archive of Mechanical Engineering
|
2021
|
LXVIII, nr 4
415--434
EN
The article describes motion planning of an underwater redundant manipulator with revolute joints moving in a plane under gravity and in the presence of obstacles. The proposed motion planning algorithm is based on minimization of the total energy in overcoming the hydrodynamic as well as dynamic forces acting on the manipulator while moving underwater and at the same time, avoiding both singularities and obstacle. The obstacle is considered as a point object. A recursive Lagrangian dynamics algorithm is formulated for the planar geometry to evaluate joint torques during the motion of serial link redundant manipulator fully submerged underwater. In turn the energy consumed in following a task trajectory is computed. The presence of redundancy in joint space of the manipulator facilitates selecting the optimal sequence of configurations as well as the required joint motion rates with minimum energy consumed among all possible configurations and rates. The effectiveness of the proposed motion planning algorithm is shown by applying it on a 3 degrees-of-freedom planar redundant manipulator fully submerged underwater and avoiding a point obstacle. The results establish that energy spent against overcoming loading resulted from hydrodynamic interactions majorly decides the optimal trajectory to follow in accomplishing an underwater task.
5
Content available Multiquery motion planning in uncertain spaces: Incremental adaptive randomized roadmaps
Khaksar Weria, Uddin Md Zia, Torresen Jim
International Journal of Applied Mathematics and Computer Science
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2019
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Vol. 29, no. 4
641--654
EN
Sampling-based motion planning is a powerful tool in solving the motion planning problem for a variety of different robotic platforms. As its application domains grow, more complicated planning problems arise that challenge the functionality of these planners. One of the main challenges in the implementation of a sampling-based planner is its weak performance when reacting to uncertainty in robot motion, obstacles motion, and sensing noise. In this paper, a multi-query sampling-based planner is presented based on the optimal probabilistic roadmaps algorithm that employs a hybrid sample classification and graph adjustment strategy to handle diverse types of planning uncertainty such as sensing noise, unknown static and dynamic obstacles and an inaccurate environment map in a discrete-time system. The proposed method starts by storing the collision-free generated samples in a matrix-grid structure. Using the resulting grid structure makes it computationally cheap to search and find samples in a specific region. As soon as the robot senses an obstacle during the execution of the initial plan, the occupied grid cells are detected, relevant samples are selected, and in-collision vertices are removed within the vision range of the robot. Furthermore, a second layer of nodes connected to the current direct neighbors are checked against collision, which gives the planner more time to react to uncertainty before getting too close to an obstacle. The simulation results for problems with various sources of uncertainty show a significant improvement compared with similar algorithms in terms of the failure rate, the processing time and the minimum distance from obstacles. The planner is also successfully implemented and tested on a TurtleBot in four different scenarios with uncertainty.
6
Legal and technical aspects of the safety of autonomous vehicles
Wicher J.
Zeszyty Naukowe Instytutu Pojazdów / Politechnika Warszawska
|
2018
|
z. 3/117
5--18
EN
The article is presented the predicted effects of the dissemination of autonomous vehicles and the consequences of exploiting the opportunities that modern traffic control systems can achieve. Attention has been paid to the need for using high processing power systems in vehicles and several planning strategies for traffic trajectories.
PL
W artykule przedstawiono przewidywane skutki upowszechniania pojazdów autonomicznych oraz konsekwencje wykorzystania możliwości jakie są do osiągnięcia przez nowoczesne systemy sterowania nimi w ruchu drogowym. Zwrócono uwagę na konieczność stosowania w pojazdach systemów o dużej mocy obliczeniowej oraz pokazano kilka strategii planowania trajektorii ruchu.
7
Content available An evasive manoeuvre, automatically controlled to avoid the one of a group of many obstacles moving in a vicinity of flying airplane
Graffstein J.
Zeszyty Naukowe Akademii Marynarki Wojennej
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2017
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R. 58 nr 2 (209)
39--49
EN
Detection of a collision threat and an appropriate decision on passing by an obstacle are necessary for solving the problem of collision avoidance in case of aircraft motion within the airspace. In the article a method for detecting a threat of collision with the obstacle is presented for the case of many moving objects appearing within the neighbourhood of the aircraft. The analysis of an algorithm for making a preliminary decision on avoiding a collision with more than one moving obstacle was carried out. The shape of a class of evasive trajectories was proposed, and its reliability was proved. Numerical simulations of flight were completed for the considered type of aircraft in aforementioned conditions. The scope of these simulations covered all phases of obstacle avoiding manoeuvre, including a return to a straight-line part of flight trajectory pre planned before the start.
PL
Do rozwiązania problemu unikania przeszkód przez poruszający się samolot w przestrzeni powietrznej niezbędne jest wykrycie zagrożenia kolizji oraz podjęcie właściwej decyzji o sposobie ominięcia przeszkody. W artykule przedstawiono sposób wykrywania niebezpieczeństwa zderzenia z przeszkodą dla przypadku, gdy w otoczeniu samolotu znajduje się wiele ruchomych obiektów. Przeprowadzono analizę algorytmu podejmowania wstępnych decyzji o sposobie unikania kolizji z więcej niż jedną ruchomą przeszkodą. Zaproponowano kształt klasy trajektorii manewru omijania i potwierdzono jej wykonalność na drodze symulacji numerycznej. Wykonano symulację numeryczną lotu przyjętego typu samolotu we wspomnianych warunkach. Zakres tych symulacji obejmował wszystkie fazy manewru omijania przeszkody, włącznie z powrotem do prostoliniowego odcinka lotu, stanowiącego fragment trasy zaplanowanej przed startem.
8
Content available Mobile Robot Path Planning with Obstacle Avoidance using Particle Swarm Optimization
Chołodowicz E., Figurowski D.
Pomiary Automatyka Robotyka
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2017
|
R. 21, nr 3
59--68
EN
This paper presents a constrained Particle Swarm Optimization (PSO) algorithm for mobile robot path planning with obstacle avoidance. The optimization problem is analyzed in static and dynamic environments. A smooth path based on cubic splines is generated by the interpolation of optimization solution; the fitness function takes into consideration the path length and obstaclegenerated repulsive zones. World data transformation is introduced to reduce the optimization algorithm computational complexity. Different scenarios are used to test the algorithm in simulation and real-world experiments. In the latter case, a virtual robot following concept is exploited as part of the control strategy. The path generated by the algorithm is presented in results along with its execution by the mobile robot.
PL
W artykule przedstawiono algorytm rojowy z ograniczeniami realizujący planowanie bezkolizyjnej ścieżki ruchu robota mobilnego. Problem optymalizacyjny został przeanalizowany dla środowiska statycznego i dynamicznego. Do stworzenia gładkiej ścieżki ruchu wykorzystano interpolację rozwiązania optymalizacji przy użyciu sześciennych funkcji sklejanych. Funkcja kosztu uwzględnia długość ścieżki ruchu oraz penalizację za naruszenie przestrzeni przeszkód. Wprowadzono transformację świata w celu redukcji złożoności obliczeniowej algorytmu optymalizacji. Przeprowadzono zróżnicowane scenariusze badawcze testujące algorytm w eksperymentach symulacyjnych i rzeczywistych. W przypadku tych ostatnich wykorzystano ideę podążania za wirtualnym robotem. Zaprezentowano wyniki obrazujące wygenerowaną ścieżkę ruchu oraz ocenę jej realizacji przez robota mobilnego.
9
Content available Computationaly simple obstacle avoidance control law for small unmanned aerial vehicles
Cieśluk J., Gosiewski Z., Ambroziak L., Romaniuk S.
Acta Mechanica et Automatica
|
2015
|
Vol. 9, no. 1
50--56
EN
The investigations of the system which allow to avoid obstacles by the unmanned aerial vehicles (UAV) are presented in the paper. The system is designed to enable the full autonomous UAV flight in an unknown environment. As an information source about obstacles digital camera was used. Developed algorithm uses the existing relations between the imaging system and the parameters read from the UAV autopilot. Synthesis of the proposed obstacle avoidance control law was oriented for computational simplicity. Presented algorithm was checked during simulation studies and in-flight tests.
10
Content available remote A learning paradigm for motion control of mobile manipulators
Abdessemed F., Monacelli E., Benmahammed K.
International Journal of Applied Mathematics and Computer Science
|
2006
|
Vol. 16, no 4
475-484
EN
Motion control of a mobile manipulator is discussed. The objective is to allow the end-effector to track a given trajectory in a fixed world frame. The motion of the platform and that of the manipulator are coordinated by a neural network which is a kind of graph designed from the kinematic model of the system. A learning paradigm is used to produce the required reference variables for each of the mobile platform and the robot manipulator for an overall coordinate behavior. Simulation results are presented to show the effectiveness of the proposed scheme.
11
Content available remote Route planning and obstacle avoiding for small robots in natural terrain
Gąsowski R.
Przegląd Elektrotechniczny
|
2004
|
R. 80, nr 4
351-353
EN
This paper describes a route planner and dynamic obstacle avoidance system to support operations for an autonomous vehicle in natural terrain. A search engine is used to search a specially prepared digitized map of the natural terrain and to generale a sub-optimal route in terms of distance, safety, and maneuvering. For obstacle avoidance, main concept is based on data from sensors mounted on the robot.
PL
Artykuł ten opisuje system planowania drogi oraz omijania przeszkód wspomagający poruszanie się autonomicznego pojazdu w terenie. "Silnik" moduły poszukującego wykorzystuje specjalnie przygotowaną do tego celu mapę naturalnego terenu. Na tej podstawie tworzona jest najoptymalniejsza droga, przy założeniu następujących kryteriów: dystansu, bezpieczeństwa oraz ilości manewrów. W przypadku omijania przeszkód główna koncepcja oparta jest na przetwarzaniu danych z sensorów umieszczonych na robocie.
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