Articoli di riviste: "Collision search"

1

Rakholiya, Kalpesh R., e Dr Dhaval Kathiriya. "Efficient Black-Box Collision Search in cryptanalysis". Paripex - Indian Journal Of Research 2, n. 1 (15 gennaio 2012): 30–31. http://dx.doi.org/10.15373/22501991/jan2013/11.

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Kim, Dong-Gyun, Katsutoshi Hirayama e Gyei-Kark Park. "Collision Avoidance in Multiple-Ship Situations by Distributed Local Search". Journal of Advanced Computational Intelligence and Intelligent Informatics 18, n. 5 (20 settembre 2014): 839–48. http://dx.doi.org/10.20965/jaciii.2014.p0839.

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Abstract (sommario):

As vital transportation carriers in trade, ships have the advantage of stability, economy, and bulk capacity over airplanes, trucks, and trains. Even so, their loss and cost due to collisions and other accidents exceed those of any other mode of transportation. To prevent ship collisions many ways have been suggested, e.g., the 1972 COLREGs which is the regulation for preventing collision between ships. Technologically speaking, many related studies have been conducted. The term “Ship domain” involves that area surrounding a ship that the navigator wants to keep other ships clear of. Ship domain alone is not sufficient, however, for enabling one or more ships to simultaneously determine the collision risk for all of the ships concerned. Fuzzy theory is useful in helping ships avoid collision in that fuzzy theory may define whether collision risk is based on distance to closest point of approach, time to closest point of approach, or relative bearing – algorithms that are difficult to apply to more than one ships at one time. The main purpose of this study is thus to reduce collision risk among multiple ships using a distributed local search algorithm (DLSA). By exchanging information on, for example, next-intended courses within a certain area among ships, ships having the maximum reduction in collision risk change courses simultaneously until all ships approach a destination without collision. In this paper, we introduce distributed local search and explain how it works using examples. We conducted experiments to test distributed local search performance for certain instances of ship collision avoidance. Experiments results showed that in most cases, our proposal applies well in ship collision avoidance amongmultiple ships.

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Fan, Yunsheng, Xiaojie Sun, Guofeng Wang e Dongdong Mu. "Collision Avoidance Controller for Unmanned Surface Vehicle Based on Improved Cuckoo Search Algorithm". Applied Sciences 11, n. 20 (19 ottobre 2021): 9741. http://dx.doi.org/10.3390/app11209741.

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For the dynamic collision avoidance problem of an unmanned surface vehicle (USV), a dynamic collision avoidance control method based on an improved cuckoo search algorithm is proposed. The collision avoidance model for a USV and obstacles is established on the basis of the principle of the velocity obstacle method. Simultaneously, the Convention on the International Regulations for Preventing Collisions at Sea (COLREGS) is incorporated in the collision avoidance process. For the improvement of the cuckoo algorithm, the adaptive variable step-size factor is designed to realize the adaptive adjustment of flight step-size, and a mutation and crossover strategy is introduced to enhance the population diversity and improve the global optimization ability. The improved cuckoo search algorithm is applied to the collision avoidance model to obtain an optimal collision avoidance strategy. According to the collision avoidance strategy, the desired evasion trajectory is obtained, and the tracking controller based on PID is used for the Lanxin USV. The experimental results show the feasibility and effectiveness of the proposed collision avoidance method, which provides a solution for the autonomous dynamic collision avoidance of USVs.

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Chen, Jian Zhe, Gui Tang Wang, Mei Shao e Ying Ge Li. "An Improved Multi-Label Anti-Collision Algorithm of RFID". Applied Mechanics and Materials 336-338 (luglio 2013): 1887–91. http://dx.doi.org/10.4028/www.scientific.net/amm.336-338.1887.

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Abstract (sommario):

When there are multiple electronic tags in the reading range of reader, It arises problem of multiple tags data collision in the data communication process of RFID system, causing the data reader have obtained error. This paper will contrapose the problem of tag collision, analysizing the search number and the system throughput rate of the existing anti-collision search algorithm based on binary, to propose an improved anti-collision algorithm. The improved algorithm reduces the redundant information of the sequence number that the reader have sent, and no longer searchs the tags of one bit collided ,but identify the two collided tags directly, thus reducing the search number of algorithm. Matlab simulation show that this algorithm can reduce the search number of reader identifying tags, improving the identifying efficiency of the RFID system, solving the problem of tag collision effectively.

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Zhang, Hang, e Jing Sha He. "An Anti-Collision Algorithm for Applications with Massive RFID Tags". Advanced Materials Research 756-759 (settembre 2013): 4011–15. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.4011.

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Anti-collision is a key technology in systems and applications in which Radio Frequency Identification (RFID) is used since it determines the efficiency of RFID tag identification. Although binary-tree search algorithms can effectively resolve collisions, they may not be very efficient in systems with a large number of RFID tags. In this paper, we propose a new flat-tree anti-collision algorithm and show that the proposed algorithm is more suitable for resolving collisions involving a massive number of RFID tags. Through analysis and experiment, we show that the flat-tree algorithm outperforms the binary-tree search algorithms when the number of RFID tags reaches a massive scale, i.e., exceeds a certain number.

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Watanabe, Kento, Jun’ichi Kaneko e Kenichiro Horio. "Development of Tool Collision Avoidance Method Adapted to Uncut Workpiece Shape". International Journal of Automation Technology 11, n. 2 (1 marzo 2017): 235–41. http://dx.doi.org/10.20965/ijat.2017.p0235.

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This study developed an automatic planning method for tool collision avoidance, with posture adapted to the uncut shape of a workpiece to avoid collisions between the tool and workpiece in five-axis machining. This method sequentially judges the likelihood of collision between the holder and shank parts of the tool and the workpiece while machining, which is updated with tool motion. Then it automatically determines tool postures in which no collisions occur. The process of setting the search range for collision avoidance postures of the tool when collisions occur is made more efficient; it is possible to prevent rapid changes in tool posture at the time of avoidance, while reducing the time for geometric operations necessary when searching for compatible orientations.

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Xu, Qingyang, Chuang Zhang e Ning Wang. "Multiobjective Optimization Based Vessel Collision Avoidance Strategy Optimization". Mathematical Problems in Engineering 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/914689.

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The vessel collision accidents cause a great loss of lives and property. In order to reduce the human fault and greatly improve the safety of marine traffic, collision avoidance strategy optimization is proposed to achieve this. In the paper, a multiobjective optimization algorithm NSGA-II is adopted to search for the optimal collision avoidance strategy considering the safety as well as economy elements of collision avoidance. Ship domain and Arena are used to evaluate the collision risk in the simulation. Based on the optimization, an optimal rudder angle is recommended to navigator for collision avoidance. In the simulation example, a crossing encounter situation is simulated, and the NSGA-II searches for the optimal collision avoidance operation under the Convention on the International Regulations for Preventing Collisions at Sea (COLREGS). The simulation studies exhibit the validity of the method.

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Byun, Hayoung, e Hyesook Lim. "Comparison on Search Failure between Hash Tables and a Functional Bloom Filter". Applied Sciences 10, n. 15 (29 luglio 2020): 5218. http://dx.doi.org/10.3390/app10155218.

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Hash-based data structures have been widely used in many applications. An intrinsic problem of hashing is collision, in which two or more elements are hashed to the same value. If a hash table is heavily loaded, more collisions would occur. Elements that could not be stored in a hash table because of the collision cause search failures. Many variant structures have been studied to reduce the number of collisions, but none of the structures completely solves the collision problem. In this paper, we claim that a functional Bloom filter (FBF) provides a lower search failure rate than hash tables, when a hash table is heavily loaded. In other words, a hash table can be replaced with an FBF because the FBF is more effective than hash tables in the search failure rate in storing a large amount of data to a limited size of memory. While hash tables require to store each input key in addition to its return value, a functional Bloom filter stores return values without input keys, because different index combinations according to each input key can be used to identify the input key. In search failure rates, we theoretically compare the FBF with hash-based data structures, such as multi-hash table, cuckoo hash table, and d-left hash table. We also provide simulation results to prove the validity of our theoretical results. The simulation results show that the search failure rates of hash tables are larger than that of the functional Bloom filter when the load factor is larger than 0.6.

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Li, Jiaoyang, Zhe Chen, Daniel Harabor, Peter J. Stuckey e Sven Koenig. "MAPF-LNS2: Fast Repairing for Multi-Agent Path Finding via Large Neighborhood Search". Proceedings of the AAAI Conference on Artificial Intelligence 36, n. 9 (28 giugno 2022): 10256–65. http://dx.doi.org/10.1609/aaai.v36i9.21266.

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Multi-Agent Path Finding (MAPF) is the problem of planning collision-free paths for multiple agents in a shared environment. In this paper, we propose a novel algorithm MAPF-LNS2 based on large neighborhood search for solving MAPF efficiently. Starting from a set of paths that contain collisions, MAPF-LNS2 repeatedly selects a subset of colliding agents and replans their paths to reduce the number of collisions until the paths become collision-free. We compare MAPF-LNS2 against a variety of state-of-the-art MAPF algorithms, including Prioritized Planning with random restarts, EECBS, and PPS, and show that MAPF-LNS2 runs significantly faster than them while still providing near-optimal solutions in most cases. MAPF-LNS2 solves 80% of the random-scenario instances with the largest number of agents from the MAPF benchmark suite with a runtime limit of just 5 minutes, which, to our knowledge, has not been achieved by any existing algorithms.

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Jiang, Ruoxi, Shunying Zhu, Pan Wang, QiuCheng Chen, He Zou e Shiping Kuang. "In Search of the Consequence Severity of Traffic Conflict". Journal of Advanced Transportation 2020 (13 luglio 2020): 1–15. http://dx.doi.org/10.1155/2020/9089817.

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Currently, many studies on the severity of traffic conflicts only considered the possibility of potential collisions but ignored the consequences severity of potential collisions. Aiming toward this defect, this study establishes a potential collision (serious conflict) consequences severity model on the basis of vehicle collision theory. Regional vehicles trajectory data and historical traffic accident data were obtained. The field data were brought into the conflict consequences severity model to calculate the conflict severity rate of each section under different TTC thresholds. For comparison, the traditional conflict rate of each section under different TTC thresholds that considered only the number of conflicts was also calculated. Results showed that the relationship between conflict severity rate and influencing factors was somehow different. The conflict severity rate seemed to have a higher correlation with accident rate and accident severity rate than conflict rate did. The TTC threshold value also affected the correlation between conflicts and accidents, with high and low TTC threshold indicating a lower correlation. The results showed that conflict severity rate that considered each single conflict consequence severity was a little better than the traditional conflict rate that considered only the numbers of conflicts in reflecting real risks as a new conflict evaluation indicator. The severity of traffic conflicts should consider two dimensions: the possibility and consequence of potential collisions. Based on this, we propose a new traffic safety evaluation method that takes into account the severity of the consequences of the conflict. More data and prediction models are needed to conduct more realistic and complex research in the future to ensure reliability of this new method.

11

Shi, Haiyun, Jie Li e Zhi Li. "A Distributed Strategy for Cooperative Autonomous Robots Using Pedestrian Behavior for Multi-Target Search in the Unknown Environment". Sensors 20, n. 6 (13 marzo 2020): 1606. http://dx.doi.org/10.3390/s20061606.

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Searching multiple targets with swarm robots is a realistic and significant problem. The goal is to search the targets in the minimum time while avoiding collisions with other robots. In this paper, inspired by pedestrian behavior, swarm robotic pedestrian behavior (SRPB) was proposed. It considered many realistic constraints in the multi-target search problem, including limited communication range, limited working time, unknown sources, unknown extrema, the arbitrary initial location of robots, non-oriented search, and no central coordination. The performance of different cooperative strategies was evaluated in terms of average time to find the first, the half, and the last source, the number of located sources and the collision rate. Several experiments with different target signals, fixed initial location, arbitrary initial location, different population sizes, and the different number of targets were implemented. It was demonstrated by numerous experiments that SRPB had excellent stability, quick source seeking, a high number of located sources, and a low collision rate in various search strategies.

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Zhu, Yongtai, Wenqing Shen, Xiaoqing Hu, Yuanxiang Xie, Wenlong Zhan, Xiang Zhu, Songlin Li et al. "Search for incomplete deep inelastic collision". Nuclear Physics A 488 (ottobre 1988): 409–22. http://dx.doi.org/10.1016/0375-9474(88)90278-3.

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13

van Oorschot, Paul C., e Michael J. Wiener. "Parallel Collision Search with Cryptanalytic Applications". Journal of Cryptology 12, n. 1 (gennaio 1999): 1–28. http://dx.doi.org/10.1007/pl00003816.

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14

Li, Chao, e Hai Ling Xiong. "Improved Binary Tree Search Anti-Collision Algorithm". Applied Mechanics and Materials 397-400 (settembre 2013): 2012–18. http://dx.doi.org/10.4028/www.scientific.net/amm.397-400.2012.

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Abstract (sommario):

According to the issue of tag collision in the radio frequency identification technology, this paper proposes a binary tree search anti-collision algorithm, which takes different processing methods according to how many continuous collision. Compared with the dynamic binary tree search algorithm, the improved algorithm reduces the query information send by the reader. At the same time,the algorithm in the process of identifying tags reduces the query information, the query number and tag response times, so as to shorten the recognition time, further improve the search performance.

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Liu, Yumei, Jiaojiao Zhuang, Shurong Wang, Xiaoning Cao e Ningguo Qiao. "Workspace analysis of the bogie 6-degree-of-freedom dynamic simulation test bench". Advances in Mechanical Engineering 11, n. 3 (marzo 2019): 168781401982714. http://dx.doi.org/10.1177/1687814019827146.

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The bogie 6-degree-of-freedom dynamic simulation test bench can simulate various operating conditions of the bogie through coordinated movement of the three parallel 6-degree-of-freedom motion platforms; however, the motion of the platforms will be interfered by some space obstacles. In order to obtain the collision-free workspace of the 6-degree-of-freedom motion platforms, a limit boundary–search method based on the collision-detection model is proposed. The structure of three parallel 6-degree-of-freedom motion platforms is analyzed, and its inverse kinematics model is established. Considering its internal constraints, the constraint models of the actuators’ stroke and the spherical hinges angle are established. Based on the collision-detection method between convex polygons, the minimum distance-detection models between platforms and obstacles as well as between actuators and obstacles are established. Then the limit boundary–search method is used to search for all boundary points that satisfy the constraint conditions. Finally, the correctness and feasibility of the proposed method and models are verified by some simulation examples. The proposed research avoids collisions effectively and provides a reference for the optimal design of the test bench.

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Ma, Wen Yao, e Jia Xuan Yang. "Collision Avoidance Strategy Optimization of Ship’s Speed Alteration with Bacterial Foraging Algorithm". Applied Mechanics and Materials 278-280 (gennaio 2013): 1318–22. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.1318.

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Abstract (sommario):

When ship navigates at sea, collision avoidance of ship’s speed alteration is frequently adopted by officer on watch in order to prevent from forming collision situation with target ship(s). Bacterial foraging algorithm (BFA) that imitates the social foraging behavior of Escherichia coli is an optimal search method suitable for complex problems. This research adopts the bacterial foraging algorithm to find the speed alteration collision avoidance strategy from an economical viewpoint, combining the international regulations for preventing collisions at sea (COLREGS) and the safety domain of ship. An optimal time of changing speed, amplitude of speed alteration and navigation restoration time will also be provided. The effectiveness of the algorithm has been verified by simulation. The study offers new thinking and a practical method for collision avoidance decision.

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Kim, Jongwan. "Hybrid Dynamic-Binary ALOHA Anti-Collision Protocol in RFID Systems". International Journal of Engineering & Technology 7, n. 2.15 (6 aprile 2018): 171. http://dx.doi.org/10.14419/ijet.v7i2.15.12566.

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Abstract (sommario):

The main techniques for identifying objects in an Internet of things environment are based on radio frequency identification, in which a specific object is identified by the reader through the tag mounted on the object. When there are multiple tags in the reader’s interrogation zone, they respond simultaneously to the reader’s request, thus causing a collision between the signals sent simultaneously to the reader from those tags. Such collisions reduce the data accuracy and prolong the identification time, thus making it difficult to provide a rapid service. This paper explores a hybrid anti-collision protocol, namely, the hybrid dynamic-binary ALOHA anti-collision protocol, which is designed to prevent tag collision and to enable more stable information transmission by improving the existing tag anti-collision protocols. The proposed protocol has achieved performance enhancement by shortening the tag identification process when tag collision occurs by combining the ALOHA and binary search protocols. In contrast to the existing protocols, whereby the reader’s request is repeated after detecting a collision, the proposed protocol shortens the tag identification time by requesting only the collision bits. This contributes to a substantial reduction in the object identification time in an IoT environment.

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Handke, Artur. "SIMPLIFIED COLLISION DETECTION IN 4R SERIAL MANIPULATORS". Acta Mechanica et Automatica 7, n. 1 (1 marzo 2013): 11–14. http://dx.doi.org/10.2478/ama-2013-0002.

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Abstract This paper concerns the problem of designating criteria for assessing the possibility of a collision between the elements of serial manipulators with three rotary joints allowing to flex the segments in common plane oriented by rotating the fourth connection. The issue of contactless and efficient functioning of described group of manipulators has been considered in the spatial system. Equations were derived determining the possibility of a collision between selected segments of both manipulators. Collision detection model isn’t based on the information from the tactile sensors, but only on the relative position between the segments of manipulators. Based on the parameters defining the collision, the search for method of impossible collision was set on designing level, in order to minimize the time needed to examine all possible scenarios of collisions between segments. The results were included in development of methods and algorithms for planning and controlling movements of finger modules in anthropomorphic manipulator during grasping objects of indeterminate shape.

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Liu, Hongyan, Daokui Qu, Fang Xu, Zhenjun Du, Kai Jia e Mingmin Liu. "An Efficient Online Trajectory Generation Method Based on Kinodynamic Path Search and Trajectory Optimization for Human-Robot Interaction Safety". Entropy 24, n. 5 (6 maggio 2022): 653. http://dx.doi.org/10.3390/e24050653.

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With the rapid development of robot perception and planning technology, robots are gradually getting rid of fixed fences and working closely with humans in shared workspaces. The safety of human-robot coexistence has become critical. Traditional motion planning methods perform poorly in dynamic environments where obstacles motion is highly uncertain. In this paper, we propose an efficient online trajectory generation method to help manipulator autonomous planning in dynamic environments. Our approach starts with an efficient kinodynamic path search algorithm that considers the links constraints and finds a safe and feasible initial trajectory with minimal control effort and time. To increase the clearance between the trajectory and obstacles and improve the smoothness, a trajectory optimization method using the B-spline convex hull property is adopted to minimize the penalty of collision cost, smoothness, and dynamical feasibility. To avoid the collisions between the links and obstacles and the collisions of the links themselves, a constraint-relaxed links collision avoidance method is developed by solving a quadratic programming problem. Compared with the existing state-of-the-art planning method for dynamic environments and advanced trajectory optimization method, our method can generate a smoother, collision-free trajectory in less time with a higher success rate. Detailed simulation comparison experiments, as well as real-world experiments, are reported to verify the effectiveness of our method.

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Zhang, Qing-hui, Qi-ming Wang e Shuying Qin. "Research on An Improved RFID Collision Algorithm". MATEC Web of Conferences 232 (2018): 03012. http://dx.doi.org/10.1051/matecconf/201823203012.

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Abstract (sommario):

Radio Frequency Identification (RFID) is a kind of information that using radio Identification technology. Anti-collision algorithm has always been a research topic for researchers. The anti-collision algorithm of labels is mainly divided into two major categories: ALOHA-Based Anti-Collision Algorithms and Anti-collision algorithm based on binary search. Both algorithms have their own advantages and disadvantages, Anti-collision algorithm that based on ALOHA is simple and fast, but it will lose labels. Binary-based anti-collision algorithm can be searched for every tag, and it is not easy to lose tags, but it is relatively complicated and has poor security. Therefore, this paper proposes an Anti-collision algorithm which combines the dynamic frame slot Anti-collision algorithm with the return binary search algorithm.

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Le, Duc-Tai, Giyeol Im, Thang Le Duc, Vyacheslav V. Zalyubovskiy, Dongsoo S. Kim e Hyunseung Choo. "Critical-Path Aware Scheduling for Latency Efficient Broadcast in Duty-Cycled Wireless Sensor Networks". Wireless Communications and Mobile Computing 2018 (22 ottobre 2018): 1–16. http://dx.doi.org/10.1155/2018/5017319.

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Minimum latency scheduling has arisen as one of the most crucial problems for broadcasting in duty-cycled Wireless Sensor Networks (WSNs). Typical solutions for the broadcast scheduling iteratively search for nodes able to transmit a message simultaneously. Other nodes are prevented from transmissions to ensure that there is no collision in a network. Such collision-preventions result in extra delays for a broadcast and may increase overall latency if the delays occur along critical paths of the network. To facilitate the broadcast latency minimization, we propose a novel approach, critical-path aware scheduling (CAS), which schedules transmissions with a preference of nodes in critical paths of a duty-cycled WSN. This paper presents two schemes employing CAS which produce collision-free and collision-tolerant broadcast schedules, respectively. The collision-free CAS scheme guarantees an approximation ratio of (Δ-1)T in terms of latency, where Δ denotes the maximum node degree in a network. By allowing collision at noncritical nodes, the collision-tolerant CAS scheme reduces up to 10.2 percent broadcast latency compared with the collision-free ones while requiring additional transmissions for the noncritical nodes experiencing collisions. Simulation results show that broadcast latencies of the two proposed schemes are significantly shorter than those of the existing methods.

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Le, Duong, e Erion Plaku. "Cooperative, Dynamics-based, and Abstraction-Guided Multi-robot Motion Planning". Journal of Artificial Intelligence Research 63 (31 ottobre 2018): 361–90. http://dx.doi.org/10.1613/jair.1.11244.

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Abstract (sommario):

This paper presents an effective, cooperative, and probabilistically-complete multi-robot motion planner that enables each robot to move to a desired location while avoiding collisions with obstacles and other robots. The approach takes into account not only the geometric constraints arising from collision avoidance, but also the differential constraints imposed by the motion dynamics of each robot. This makes it possible to generate collision-free and dynamically-feasible trajectories that can be executed in the physical world.The salient aspect of the approach is the coupling of sampling-based motion planning to handle the complexity arising from the obstacles and robot dynamics with multi-agent search to find solutions over a suitable discrete abstraction. The discrete abstraction is obtained by constructing roadmaps to solve a relaxed problem that accounts for the obstacles but not the dynamics. Sampling-based motion planning expands a motion tree in the composite state space of all the robots by adding collision-free and dynamically-feasible trajectories as branches. Efficiency is obtained by using multi-agent search to find non-conflicting routes over the discrete abstraction which serve as heuristics to guide the motion-tree expansion. When little or no progress is made, the routes are penalized and the multi-agent search is invoked again to find alternative routes. This synergistic coupling makes it possible to effectively plan collision-free and dynamically-feasible motions that enable each robot to reach its goal. Experiments using vehicle models with nonlinear dynamics operating in complex environments, where cooperation among robots is required, show significant speedups over related work.

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Bai, Le Qiang, e Xi Yang. "An Parallel Anti-Collision Algorithm Based on Adaptive Multi-Tree Search". Applied Mechanics and Materials 556-562 (maggio 2014): 3707–10. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.3707.

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Abstract (sommario):

In order to improve the unstable system throughput and reduce the "misjudgment" issues, this paper proposes a kind of parallel multi-tree search anti-collision algorithm. The algorithm embeds pseudo collision time slot with OVSF spreading code in RFID systems for identifying tags. As there are more than one code channels in a pseudo collision time slot, the slot can identify tags concurrently, reducing the accumulated collision. Theoretic analysis proves that the system throughput is improved with the increasing of code length. Simulation results show that the new algorithm has more stable and higher system throughput.

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Liu, Xiao Yue, e Pei Lei Zhang. "Research on Anti-Collision of Personnel Positioning in Underground Coal Mine Based on RFID". Applied Mechanics and Materials 380-384 (agosto 2013): 1820–23. http://dx.doi.org/10.4028/www.scientific.net/amm.380-384.1820.

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in order to avoid signal collision when two or more tags send recognizable signals to the reader of underground coal mine personnel tracking system , the binary tree search algorithm along with algorithms which improved from them is discussed, an adaptive anti-collision algorithm is proposed .In the respects of time and space the algorithm shows obvious advantages than the binary tree search algorithm ,so the probability of collision reduces greatly and the problem of collision maybe effectively solved.

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Zou, Jian, Yongyang Liu e Le Dong. "An Efficient Quantum Multi-Collision Search Algorithm". IEEE Access 8 (2020): 181619–28. http://dx.doi.org/10.1109/access.2020.3028736.

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Kim, Dong-Gyun, Katsutoshi Hirayama e Tenda Okimoto. "Ship Collision Avoidance by Distributed Tabu Search". TransNav, the International Journal on Marine Navigation and Safety of Sea Transportation 9, n. 1 (2015): 23–29. http://dx.doi.org/10.12716/1001.09.01.03.

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Hu, Zhong Yue. "Research on Anti-Collision Algorithm of Short Distance Data Communication Based on Binary-Tree Disassembly". Applied Mechanics and Materials 686 (ottobre 2014): 354–58. http://dx.doi.org/10.4028/www.scientific.net/amm.686.354.

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Abstract (sommario):

This paper puts forward adaptive anti collision algorithm based on two fork tree decomposition. New search algorithm built on the basis of binary-tree algorithm, using the uniqueness of the label EPC, to estimate the distribution of label by slot allocation, the huge and complicated two fork tree is decomposed into several simple binary-tree by search the collision slots for binary-tree, so, it can simplifies the search process. The algorithm fully considers4 important performance parameters of the reader paging times, transmission delay, energy consumption and throughput label, the simulation results show that, the improved anti-collision algorithm is obviously improved performance than other two fork tree algorithm, it is more suitable for RFID anti-collision protocols.

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Zhang, Xinyu, Chengbo Wang, Kwok Tai Chui e (Ryan) Wen Liu. "A Real-Time Collision Avoidance Framework of MASS Based on B-Spline and Optimal Decoupling Control". Sensors 21, n. 14 (19 luglio 2021): 4911. http://dx.doi.org/10.3390/s21144911.

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Abstract (sommario):

Real-time collision-avoidance navigation of autonomous ships is required by many application scenarios, such as carriage of goods by sea, search, and rescue. The collision avoidance algorithm is the core of autonomous navigation for Maritime autonomous surface ships (MASS). In order to realize real-time and free-collision under the condition of multi-ship encounter in an uncertain environment, a real-time collision avoidance framework is proposed using B-spline and optimal decoupling control. This framework takes advantage to handle the uncertain environment with limited sensing MASS which plans dynamically feasible, highly reliable, and safe feasible collision avoidance. First, owing to the collision risk assessment, a B-spline-based collision avoidance trajectory search (BCATS) algorithm is proposed to generate free-collision trajectories effectively. Second, a waypoint-based collision avoidance trajectory optimization is proposed with the path-speed decoupling control. Two benefits, a reduction of control cost and an improvement in the smoothness of the collision avoidance trajectory, are delivered. Finally, we conducted an experiment using the Electronic Chart System (ECS). The results reveal the robustness and real-time collision avoidance trajectory planned by the proposed collision avoidance system.

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Kwon, Ki-Youn, Namkug Ku e Jaeyong Lee. "Design of a Display Structure for an Anti-Collision System of Offshore Drilling Units Based on the Digital Twin Concept". Journal of Marine Science and Engineering 10, n. 12 (28 novembre 2022): 1825. http://dx.doi.org/10.3390/jmse10121825.

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The drill floor of an offshore drilling facility is equipped with a collision avoidance system to prevent collisions between moving equipment. In this paper, we present the visualization of the collision avoidance system using the digital twin concept. By classifying the core technologies of the digital twin, the elements necessary for the visualization of the collision avoidance system are derived, and the information for visualization is organized. We conduct 3D visualization of equipment and design IO devices necessary for the visualization. The movement of the floater is considered, and a database is built to efficiently search for the information required for the retrieval of stored 3D information. A collision detection situation is generated by operating the equipment using the input device required for simulation. Collision information is displayed as designed, and it is confirmed that the switching of the display between the present and past time is operating normally. The entire system functions normally as designed, including the input/output with other databases and equipment operation. Implementing a digital twin for an offshore platform is a time-consuming and costly process. It is expected that the improved anti-collision system can be expanded for the digital twin of an entire offshore platform.

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Yang, Zhen Yu, Juan Xing e Xin Gang Wang. "Segment Slot Partial Competitive Anti-Collision Algorithm for RFID System". Applied Mechanics and Materials 148-149 (dicembre 2011): 753–56. http://dx.doi.org/10.4028/www.scientific.net/amm.148-149.753.

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Slot partial competitive (SPC) anti-collision algorithm is based on the ISO/IEC18000-6C UHF radio frequency identification (RFID) standard, which introduces dynamic binary tree search technology into the competitive collision avoidance mechanism. Moreover, the SPC algorithm applies the specific technologies to idle slots and collision slots. This paper proposes a segment slot partial competitive (SSPC) anti-collision algorithm based on the SPC, and introduce the segment algorithm. The performances of the dynamic binary tree search, the SPC algorithm and the SSPC algorithm are compared via simulation experiments. Simulation results indicate that the SSPC algorithm is improved significantly.

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Chan, Shao-Hung, Roni Stern, Ariel Felner e Sven Koenig. "Greedy Priority-Based Search for Suboptimal Multi-Agent Path Finding". Proceedings of the International Symposium on Combinatorial Search 16, n. 1 (2 luglio 2023): 11–19. http://dx.doi.org/10.1609/socs.v16i1.27278.

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Multi-Agent Path Finding (MAPF) is the problem of finding collision-free paths, one for each agent, in a shared environment, while minimizing their sum of travel times. Since solving MAPF optimally is NP-hard, researchers have explored algorithms that solve MAPF suboptimally but efficiently. Priority-Based Search (PBS) is the leading algorithm for this purpose. It finds paths for individual agents, one at a time, and resolves collisions by assigning priorities to the colliding agents and replanning their paths during its search. However, PBS becomes ineffective for MAPF instances with high densities of agents and obstacles. Therefore, we introduce Greedy PBS (GPBS), which uses greedy strategies to speed up PBS by minimizing the number of collisions between agents. We then propose techniques that speed up GPBS further, namely partial expansions, target reasoning, induced constraints, and soft restarts. We show that GPBS with all these improvements has a higher success rate than the state-of-the-art suboptimal algorithm for a 1-minute runtime limit, especially for MAPF instances with small maps and dense obstacles.

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Mitsou, Vasiliki A. "First search for magnetic monopoles through the Schwinger mechanism". Journal of Physics: Conference Series 2375, n. 1 (1 novembre 2022): 012002. http://dx.doi.org/10.1088/1742-6596/2375/1/012002.

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Abstract Magnetic monopoles are hypothetical fundamental particles predicted in several theories beyond the standard model, however they have never been experimentally detected. The Schwinger mechanism predicts that an extremely strong magnetic field would produce isolated magnetic charges, if they exist. Looking for the existence of magnetic monopoles via the Schwinger mechanism had not been attempted before, but it is advantageous, owing to the possibility of calculating its rate through semi-classical techniques without perturbation theory. This paper focuses on the first search for magnetic monopoles produced by the Schwinger mechanism in heavy-ion collisions. It was carried out by the MoEDAL experiment, whose trapping detectors were exposed to 0.235 nb−1 of Pb-Pb collisions with 5.02 TeV energy per collision at the LHC, that provided the strongest known magnetic fields in the universe. A superconducting quantum interference device magnetometer scanned these detectors for the presence of magnetic charge. Magnetic monopoles with 1, 2 and 3 Dirac charges and masses up to 75 GeV were excluded by the analysis. This analysis, which has been published in the journal Nature, provided a lower mass limit for finite-size magnetic monopoles from a collider search and greatly extended previous mass bounds.

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Aleksandrowicz, Iwo, e Piotr Aleksandrowicz. "Optimising post- collision repair costs with the use of the audanet system with 3d intelligent graphics". MATEC Web of Conferences 351 (2021): 01024. http://dx.doi.org/10.1051/matecconf/202135101024.

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Transporting people and goods poses a risk of participating in road collisions which results in damage to be eliminated to bring the car back to operation. When running a business, it is essential to optimise the repair costs. Also, the insurance companies search for repair cost determination methods adequately to the damage incurred. Currently the post-collision cost calculations are supported by specialised IT tools offering various spare parts assortments to be used for repair, painting methods as well as the process of technological replacement of the elements damaged. Cars, due to their complex structure, require a new approach to the process of determining the size of damage and the resulting repair cost. The article covers the problem of optimising the post-collision repair costs while using 3D Intelligent Graphics of AudaNet. The procedures presented in the article can be used by researchers modelling technological post-collision repair processes and they are applicable.

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Du, Fangwei, Hong Wang e Zhi Ma. "Quantum collision search algorithm against New FORK-256". Journal of Electronics (China) 31, n. 4 (agosto 2014): 366–70. http://dx.doi.org/10.1007/s11767-014-3146-2.

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Lin, Yue, Jianming Wang, Xuan Xiao, Ji Qu e Fatao Qin. "A snake-inspired path planning algorithm based on reinforcement learning and self-motion for hyper-redundant manipulators". International Journal of Advanced Robotic Systems 19, n. 4 (1 luglio 2022): 172988062211100. http://dx.doi.org/10.1177/17298806221110022.

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Redundant manipulators are flexible enough to adapt to complex environments, but their controller is also required to be specific for their extra degrees of freedom. Inspired by the morphology of snakes, we propose a path planning algorithm named Swinging Search and Crawling Control, which allows the snake-like redundant manipulators to explore in complex pipeline environments without collision. The proposed algorithm consists of the Swinging Search and the Crawling Control. In Swinging Search, a collision-free manipulator configuration that of the end-effector in the target point is found by applying reinforcement learning to self-motion, instead of designing joint motion. The self-motion narrows the search space to the null space, and the reinforcement learning makes the algorithm use the information of the environment, instead of blindly searching. Then in Crawling Control, the manipulator is controlled to crawl to the target point like a snake along the collision-free configuration. It only needs to search for a collision-free configuration for the manipulator, instead of searching collision-free configurations throughout the process of path planning. Simulation experiments show that the algorithm can complete path planning tasks of hyper-redundant manipulators in complex environments. The 16 degrees of freedom and 24 degrees of freedom manipulators can achieve 83.3% and 96.7% success rates in the pipe, respectively. In the concentric pipe, the 24 degrees of freedom manipulator has a success rate of 96.1%.

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Pal, Kamalendu. "RFID Tag Collision Problem in Supply Chain Management". International Journal of Advanced Pervasive and Ubiquitous Computing 11, n. 3 (luglio 2019): 1–12. http://dx.doi.org/10.4018/ijapuc.2019070101.

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The use of Radio Frequency Identification (RFID) technology has attracted a huge attention from the supply chain business community. This is due to the use of RFID technology wide range of applications in the fields of logistics and supply chain management. This paper presents a brief overview of a simple industrial RFID system and then describe the basic concept of tag collision problem. Despite many useful applications, the RFID tag collision creates a major problem for fast tag identification process. There are different algorithmic solutions available to overcome tag collision problem in industrial supply chains. Based on binary search algorithm (BSA) of dynamic and backtracking, two variations of binary anti-collision search algorithms for tag identification processes are described in this paper. Simulation-based experimental results on the performance of these algorithms are evaluated when handling multiple RFID tags simultaneously. The backtracking binary search algorithm has obvious advantages in terms of tag identification process compared to the other two algorithms.

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Xiang, Bo, e Yongqiang Zhuo. "CIPSO-Based Decision Support Method for Collision Avoidance of Super-Large Vessel in Port Waters". Applied Sciences 13, n. 19 (9 ottobre 2023): 11100. http://dx.doi.org/10.3390/app131911100.

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Effective and timely collision avoidance decision support is essential for super-large vessels navigating in port waters. To guarantee the navigational safety of super-large vessels, this work proposes a collision avoidance decision support method based on the curve increment strategy with adaptive particle swarm optimization (CIPSO). Firstly, the objective function is constructed based on the multi-objective optimization method. Here, a fuzzy comprehensive evaluation (FCE)-based vessel collision hazard model and vessel speed-varying energy-loss model integrating the Convention on the International Regulations for Preventing Collisions at Sea (COLREGS) are involved. Furthermore, in response to the limitations of the PSO algorithm, which is prone to falling into local optima in the later stages of iteration, a curve increment strategy is incorporated. To improve the performance of the global optimization, it is optimized using a local followed by global search method. The iterative evolution of CIPSO is used to obtain the optimal decision value in the set domain of feasible solutions. Finally, the effectiveness and feasibility of the proposed method are verified by the numerical simulation and large vessel maneuvering simulator, which can provide collision avoidance decision support for ship pilots.

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Hong, Zhang, Xing Hui Zhang e Jian Li Guo. "Research on Anti-Collision Technology with Multiple Tags for RFID System". Applied Mechanics and Materials 130-134 (ottobre 2011): 2124–27. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.2124.

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ALOHA algorithm can’t prevent collision much effectively, the process of anti-collision is longer while the amount of tags plunged collision is numerous, and sometimes the problem about estimating mistakenly arises. Binary search algorithm, which identification efficiency is higher, the problem about estimating mistakenly can’t arise, but its delay tima is more longer, security is short. The amelioration algorithm, return binary search algorithm can identify tag more effectively and rapidly, identifying time and the amount of tags is the relation of line form. The significance is very momentous that vast goods are identified, traced and managed by this amelioration algorithm.

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Gan, Wei, e Ying Hua Zhou. "An Improved Method of Hash Table Based on Transform and Conquer". Applied Mechanics and Materials 556-562 (maggio 2014): 6203–6. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.6203.

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This paper presented a improved method of hash table, the algorithm based on transform and conquer, established a number of small-scale array, then imitated binary search processes and reduced the hash collision. Simulation results shows that , not only the continuous memory requirement is reduced greatly, but also that when the hash collisions occur, the searching efficiency is improved by an order of magnitude from O(n) to O(logn), the space utilization rate is also improved greatly.

40

Lee, S. W., B. H. Lee e K. D. Lee. "A configuration space approach to collision avoidance of a two-robot system". Robotica 17, n. 2 (marzo 1999): 131–41. http://dx.doi.org/10.1017/s0263574799001113.

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This paper suggests an efficient approach to collision avoidance of a practical two-robot system. The approach is based on the C-space of one robot, and we consider only two and three dimensional C-space in which nearly all industrial manipulators can be reasonably represented for collision avoidance problems. The C-space of one robot is discretized with the concentric circles or spheres centered at the goal configuration. We then introduce the concept of free arc which is a set of the candidate configuration points on the concentric circle or sphere at each sampling time to avoid collisions. It is represented simply with respect to the coordinate frame attached to the goal configuration. The free arc is used as a tool for collision avoidance of a two-robot system and sub-optimality can be considered in determining a collision-free path. The main contribution of this paper is that it provides a method to construct C-obstacles in a time-varying environment more efficiently than the existing methods (e.g. slice projection method1) by restricting the search space at the expense of sacrificing completeness. Thus, it enables us to implement a practical collision avoidance algorithm for a two-robot system with decreased computational cost. Simulation results for two 2-d.o.f. manipulators and two PUMA robots are presented to show the efficacy of the proposed method.

41

Salinas, Carlos F. "Restricted visibility: In Search of a Solution". Journal of Navigation 59, n. 2 (6 aprile 2006): 349–58. http://dx.doi.org/10.1017/s037346330621378x.

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In order to avoid a collision it has clearly been proved that for most seafarers there exists a set of possible situations known as head-on, crossing and overtaking, while ignoring in a general way the behaviour they should carry out when their vessel is in conditions of restricted visibility. It is obvious that the existence of two different manoeuvre methods in relation to the prevailing visibility confuses the navigator. But there is still more. With the arrival of AIS, the present wording of paragraph d) of Rule 19 leaves the seafarer in a state of total uncertainty when deciding the appropriate manoeuvre, so its amendment must be dealt with as a maximum priority. The following paper tries to find a solution to the dilemma, even though this does not imply a radical change in the general conception that a mariner may have of collision avoidance.

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Koszelew, Jolanta, Joanna Karbowska-Chilinska, Krzysztof Ostrowski, Piotr Kuczyński, Eric Kulbiej e Piotr Wołejsza. "Beam Search Algorithm for Anti-Collision Trajectory Planning for Many-to-Many Encounter Situations with Autonomous Surface Vehicles". Sensors 20, n. 15 (24 luglio 2020): 4115. http://dx.doi.org/10.3390/s20154115.

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A single anti-collision trajectory generation problem for an “own” vessel only is significantly different from the challenge of generating a whole set of safe trajectories for multi-surface vehicle encounter situations in the open sea. Effective solutions for such problems are needed these days, as we are entering the era of autonomous ships. The article specifies the problem of anti-collision trajectory planning in many-to-many encounter situations. The proposed original multi-surface vehicle beam search algorithm (MBSA), based on the beam search strategy, solves the problem. The general idea of the MBSA involves the application of a solution for one-to-many encounter situations (using the beam search algorithm, BSA), which was tested on real automated radar plotting aid (ARPA) and automatic identification system (AIS) data. The test results for the MBSA were from simulated data, which are discussed in the final part. The article specifies the problem of anti-collision trajectory planning in many-to-many encounter situations involving moving autonomous surface vehicles, excluding Collision Regulations (COLREGs) and vehicle dynamics.

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Mishra, D. K., P. Garg, P. K. Netrakanti, L. M. Pant e A. K. Mohanty. "Experimental Results on Charge Fluctuations in Heavy-Ion Collisions". Advances in High Energy Physics 2017 (2017): 1–14. http://dx.doi.org/10.1155/2017/1453045.

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We present a subset of experimental results on charge fluctuation from the heavy-ion collisions to search for phase transition and location of critical point in the QCD phase diagram. Measurements from the heavy-ion experiments at the SPS and RHIC energies observe that total charge fluctuations increase from central to peripheral collisions. The net-charge fluctuations in terms of dynamical fluctuation measure ν(+-,dyn) are studied as a function of collision energy (sNN) and centrality of the collisions. The product of ν(+-,dyn) and 〈Nch〉 shows a monotonic decrease with collision energies, which indicates that at LHC energy the fluctuations have their origin in the QGP phase. The fluctuations in terms of higher moments of net-proton, net-electric charge, and net-kaon have been measured for various sNN. Deviations are observed in both Sσ and κσ2 for net-proton multiplicity distributions from the Skellam and hadron resonance gas model for sNN<39 GeV. Higher moment results of the net-electric charge and net-kaon do not observe any significant nonmonotonic behavior as a function of collision energy. We also discuss the extraction of the freeze-out parameters using particle ratios and experimentally measured higher moments of net-charge fluctuations. The extracted freeze-out parameters from experimentally measured moments and lattice calculations are found to be in agreement with the results obtained from the fit of particle ratios to the thermal model calculations.

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Corbet, A. G. "Towards Global Marine Traffic Control — the Need, the Technical Feasibility and the Social and Political Impediments". Journal of Navigation 45, n. 3 (settembre 1992): 425–39. http://dx.doi.org/10.1017/s0373463300010985.

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1. Introduction. Active MTC (Marine Traffic Control), in its various forms, is at present mainly confined to port areas and canals and their approaches, whereas all other areas are mainly subject to passive MTC measures; that is, the Collision Regulations, including traffic separation schemes, areas to be avoided by certain classes of vessels, deep water routes, etc. The Collision Regulations, however, despite many attempts to improve them, are fundamentally flawed by specious logic sanctioned, unfortunately, by legislation which is supported in turn by the well-meaning connivance of the courts. This paper highlights some of the insoluble problems of the Collision Regulations and looks at the planning of ocean passages, weather routeing, search and rescue, and fishery protection; and shows that there is already a measure of active MTC in these areas of activity. The future possibility of a comprehensive global active MTC system to deal with avoidance of collisions and strandings, in addition to those other activities, is considered with respect to technical feasibility and to social and political impediments.

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Yao, Jiyu, e Longhui Gang. "Ship Collaborative Path Planning Method Based on CS-STHA". Journal of Marine Science and Engineering 10, n. 10 (16 ottobre 2022): 1504. http://dx.doi.org/10.3390/jmse10101504.

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Ship path planning is one of the key technologies for ship automation. Establishing a cooperative collision avoidance (CA) path for multi-ship encounters is of great value to maritime intelligent transportation. This study aims to solve the problem of multi-ship collaborative collision avoidance based on the algorithm of Conflict Search (CS) and Space-Time Hybrid A-star (STHA). First, a static CA path is searched for each ship by using the space-time Hybrid A-star algorithm, and the conflict risk area is determined according to the ship safety distance constraint and fuzzy Collision Risk Index (CRI). Secondly, the space-time conflict constraint is introduced into the multi-ship cooperative CA scheme, and the binary tree is used to search for an optimal navigation path with no conflict and low cost. In addition, the optimal path is smoothed by using cubic interpolation to make the path consistent with actual navigation practice and ship maneuvering characteristics. Finally, considering the constraints of the International Regulations for Preventing Collisions at Sea (COLREGs), the typical two-ship and multi-ship encounter scenarios are designed and simulated to verify the effectiveness of the proposed method. Furthermore, a comparative analysis of actual encounters and encounters based on CS-STHA is also carried out. The results indicate that the proposed algorithm in the study can obtain an optimal CA path effectively and provide a reference of CA decision-making for autonomous ships.

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García, Enol, José R. Villar, Qing Tan, Javier Sedano e Camelia Chira. "An efficient multi-robot path planning solution using A* and coevolutionary algorithms". Integrated Computer-Aided Engineering 30, n. 1 (24 novembre 2022): 41–52. http://dx.doi.org/10.3233/ica-220695.

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Multi-robot path planning has evolved from research to real applications in warehouses and other domains; the knowledge on this topic is reflected in the large amount of related research published in recent years on international journals. The main focus of existing research relates to the generation of efficient routes, relying the collision detection to the local sensory system and creating a solution based on local search methods. This approach implies the robots having a good sensory system and also the computation capabilities to take decisions on the fly. In some controlled environments, such as virtual labs or industrial plants, these restrictions overtake the actual needs as simpler robots are sufficient. Therefore, the multi-robot path planning must solve the collisions beforehand. This study focuses on the generation of efficient collision-free multi-robot path planning solutions for such controlled environments, extending our previous research. The proposal combines the optimization capabilities of the A* algorithm with the search capabilities of co-evolutionary algorithms. The outcome is a set of routes, either from A* or from the co-evolutionary process, that are collision-free; this set is generated in real-time and makes its implementation on edge-computing devices feasible. Although further research is needed to reduce the computational time, the computational experiments performed in this study confirm a good performance of the proposed approach in solving complex cases where well-known alternatives, such as M* or WHCA, fail in finding suitable solutions.

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Zhao, Yan Ru, e Wei Li Miao. "An Improved Algorithm for Multi-Tag Anti-Collision in RFID System". Advanced Materials Research 989-994 (luglio 2014): 1905–8. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.1905.

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With the development of Radio Frequency Identification (RFID) technology, it also exposed some problems in practical applications. Especially in multi-tag anti-collision problem, how to quickly identify multiple tags in the scope of the reader has become the key to solve the problem. On the basis of the Binary Search Algorithm (BSA) and Dynamic Binary Search Algorithm (DBSA), the paper proposed an Improved Dynamic Binary Search Algorithm. The simulation result proves that the improved method in multi-tag anti-collision is more efficiency than the previous two, which is a good solution to the shortcomings of the first two algorithms.

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Riabov, Victor. "Recent results from PHENIX at RHIC". EPJ Web of Conferences 204 (2019): 01017. http://dx.doi.org/10.1051/epjconf/201920401017.

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The PHENIX experiment at the relativistic heavy ion collider (RHIC) finished data taking in 2016. However, large datasets collected in different collision systems (p+p, p+A and A+A) at different energies (√sNN = 19-500 GeV) during the last years of the detector operation are actively analysed by the collaboration and bring a wealth of new experimental results. This paper reviews the most recent PHENIX results on the light flavour hadron production, yields and angular correlations of the direct photons in heavy-ion collisions as well as on the search for the onset of collectivity in high multiplicity p+p and p+A collisions.

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Xin, Xin, Abhishek Nagar, Gaurav Srivastava, Zhu Li, Felix Fernandes e Aggelos K. Katsaggelos. "Large Visual Repository Search with Hash Collision Design Optimization". IEEE MultiMedia 20, n. 2 (aprile 2013): 62–71. http://dx.doi.org/10.1109/mmul.2013.22.

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Karbowska-Chilinska, Joanna, Jolanta Koszelew, Krzysztof Ostrowski, Piotr Kuczynski, Eric Kulbiej e Piotr Wolejsza. "Beam Search Algorithm for Ship Anti-Collision Trajectory Planning". Sensors 19, n. 24 (4 dicembre 2019): 5338. http://dx.doi.org/10.3390/s19245338.

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The biggest challenges in the maritime environment are accidents and excessive fuel consumption. In order to improve the safety of navigation at sea and to reduce fuel consumption, the strategy of anti-collision, shortest trajectory planning is proposed. The strategy described in this paper is based on the beam search method. The beam search algorithm (BSA) takes into account many safe trajectories for the present ship and chooses the best in terms of length and other criteria. The risk of collision of present ship with any target ships is detected when the closest point of approach (CPA) of the present ship is violated by the target ship’s planned trajectory. Only course alteration of the present ship is applied, and not speed alteration. The algorithm has been implemented in the decision support system NAVDEC and tested in a real navigation environment on the m/f Wolin, a Polish ferry. Almost all BSA trajectories calculated were shorter in comparison to the standard NAVDEC-calculated algorithm.

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