Manoeuvring Times, Domains and Arenas

1983 ◽  
Vol 36 (2) ◽  
pp. 324-328 ◽  
Author(s):  
B. A. Colley ◽  
R. G. Curtis ◽  
C. T. Stockel
Keyword(s):  
Mathematical Modelling ◽  
Collision Avoidance ◽  
Computer Model ◽  
Relative Velocity ◽  
Avoidance Manoeuvre ◽  
Stationary Objects ◽  
Computer Analyses ◽  
Ship Tracks ◽  
Radar Simulator

Two main concepts in mathematical modelling of ship encounters have been proposed by Davis. The first, the ‘domain’, was an adaptation of a concept originally introduced by Goodwin, who defined the domain as the ‘area about own-ship that a navigator wished to keep free with respect to ships and other stationary objects’. The second, the ‘arena’, conceived by Davis, is the area around the domain which when infringed causes the mariner to consider whether to make a collision-avoidance manoeuvre. Thus, in a computer model, when a vessel enters the arena the computer analyses the situation and, depending on the severity of the threat, makes a collision-avoidance manoeuvre.Goodwin's domain was divided into three sectors corresponding to the ‘giveway’, the ‘stand-on’ and the ‘overtaking’ regions as defined by the relative velocity of approach. The domain was derived from radar films of ship tracks and records of radar simulator experiments. Davis smoothed the sectored domain to a circle with own-ship off-centred astern and to port, and the weighting of each of the sectors retained. Davis's domain had a solid theoretical grounding; the arena, however, was simply a larger version of the smoothed domain. Its size and position were obtained by means of a well-distributed questionnaire. It served its purpose in the model, but lacked any real validation.One problem with the Davis arena was its inability automatically to take into account different velocities, both of own-ship and of targets.

scholarly journals Collision Avoidance on Unmanned Aerial Vehicles Using Neural Network Pipelines and Flow Clustering Techniques

2021 ◽  
Vol 13 (13) ◽  
pp. 2643
Author(s):  
Dário Pedro ◽  
João P. Matos-Carvalho ◽  
José M. Fonseca ◽  
André Mora
Keyword(s):  
Collision Avoidance ◽  
Autonomous Vehicles ◽  
High Demand ◽  
Novel Approach ◽  
Vision Sensors ◽  
Learning Techniques ◽  
Stationary Objects ◽  
Computationally Intensive ◽  
Unmanned Autonomous Vehicles ◽  
Positive Results

Unmanned Autonomous Vehicles (UAV), while not a recent invention, have recently acquired a prominent position in many industries, and they are increasingly used not only by avid customers, but also in high-demand technical use-cases, and will have a significant societal effect in the coming years. However, the use of UAVs is fraught with significant safety threats, such as collisions with dynamic obstacles (other UAVs, birds, or randomly thrown objects). This research focuses on a safety problem that is often overlooked due to a lack of technology and solutions to address it: collisions with non-stationary objects. A novel approach is described that employs deep learning techniques to solve the computationally intensive problem of real-time collision avoidance with dynamic objects using off-the-shelf commercial vision sensors. The suggested approach’s viability was corroborated by multiple experiments, firstly in simulation, and afterward in a concrete real-world case, that consists of dodging a thrown ball. A novel video dataset was created and made available for this purpose, and transfer learning was also tested, with positive results.

Methods of Collision Avoidance by Radar

1991 ◽  
Vol 44 (1) ◽  
pp. 97-109
Author(s):  
Zhao Jing-song ◽  
Wang Feng-chen
Keyword(s):  
Collision Avoidance ◽  
Radar Simulator ◽  
Chinese Marine

In this paper, the methods of collision avoidance by radar which have been used in the radar simulator course at Chinese marine colleges are introduced. Then some other methods of estimating the risk of collision, safe passing distance and course alteration in radar collision avoidance are presented.

scholarly journals Collision-avoidance and flocking in the Cucker–Smale-type model with a discontinuous controller

2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Jianfei Cheng ◽  
Xiao Wang ◽  
Yicheng Liu
Keyword(s):  
Weight Function ◽  
Collision Avoidance ◽  
Upper Bound ◽  
Finite Time ◽  
Relative Velocity ◽  
Sufficient Conditions ◽  
Repulsive Force ◽  
Type Model ◽  
Movement Tendency ◽  
Special Case

<p style='text-indent:20px;'>The collision-avoidance and flocking of the Cucker–Smale-type model with a discontinuous controller are studied. The controller considered in this paper provides a force between agents that switches between the attractive force and the repulsive force according to the movement tendency between agents. The results of collision-avoidance are closely related to the weight function <inline-formula><tex-math id="M1">\begin{document}$ f(r) = (r-d_0)^{-\theta } $\end{document}</tex-math></inline-formula>. For <inline-formula><tex-math id="M2">\begin{document}$ \theta \ge 1 $\end{document}</tex-math></inline-formula>, collision will not appear in the system if agents' initial positions are different. For the case <inline-formula><tex-math id="M3">\begin{document}$ \theta \in [0,1) $\end{document}</tex-math></inline-formula> that not considered in previous work, the limits of initial configurations to guarantee collision-avoidance are given. Moreover, on the basis of collision-avoidance, we point out the impacts of <inline-formula><tex-math id="M4">\begin{document}$ \psi (r) = (1+r^2)^{-\beta } $\end{document}</tex-math></inline-formula> and <inline-formula><tex-math id="M5">\begin{document}$ f(r) $\end{document}</tex-math></inline-formula> on the flocking behaviour and give the decay rate of relative velocity. We also estimate the lower and upper bound of distance between agents. Finally, for the special case that agents moving on the 1-D space, we give sufficient conditions for the finite-time flocking.</p>

scholarly journals Factors Influencing the Action Point of the Collision Avoidance Manoeuvre

2021 ◽  
Vol 11 (16) ◽  
pp. 7299
Author(s):  
Marcin Przywarty ◽  
Renata Boć ◽  
Tanja Brcko ◽  
Marko Perkovič
Keyword(s):  
Collision Avoidance ◽  
Safety Management ◽  
Action Point ◽  
Avoidance Manoeuvre ◽  
Problematic Issue ◽  
The Face ◽  
The Moment ◽  
Two Stages ◽  
Actual Decision ◽  
Made In

Perhaps the most problematic issue regarding navigation safety management is the unknown, or unknowable, is the navigator’s decision made in the face of a dangerous situation. This applies particularly to collision-avoidance. The aim of the article is to identify factors that influence the moment of decision during a collision-avoidance manoeuvre and to define theoretical distributions that can be used during modelling of a navigator’s behaviour. The applicable research was divided into two stages. In the first, the distance between ships and the time to closest point of approach (TCPA) were analysed. In the second, the influence of the size of the target ships and relative speed were investigated. The advantage of the paper is its use of actual observations collected in real situations. The proposed approach allows for a better understanding of the navigator’s actual decision-making, which will be instructive in measures taken to improve navigational safety.

Distributed Observer Type Protocol for Flocking of Linear Second-Order Multi-Agent Systems Subject to External Disturbance

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Sahar Yazdani ◽  
Mohammad Haeri
Keyword(s):  
Collision Avoidance ◽  
Relative Velocity ◽  
External Disturbance ◽  
Second Order ◽  
Multi Agent Systems ◽  
State Information ◽  
Agent Systems ◽  
Full State ◽  
Multi Agent ◽  
Virtual Leader

This paper studies the leader–follower flocking of multi-agent systems for the linear second-order dynamics, subject to the external disturbance problem. It is assumed that the dynamic of the leader is Lipschitz-type. Also, the velocity is the output of the system, and full-state information is not available for feedback. A distributed full-order observer is employed to estimate every agent's states and external disturbance. A control protocol for each agent is designed based on the measurement of its output/velocity and relative velocity of its neighbors. Under the proposed protocol, the velocity convergence of whole agents to the velocity of the virtual leader is guaranteed as well as the connectivity of network and collision avoidance among agents are ensured. Finally, a simulation example is provided to show the effectiveness of the results.

Reducing the Complexity When Modelling Damping in Vibrating Systems

2012 ◽  
Author(s):  
Hugh Goyder
Keyword(s):  
Computer Simulations ◽  
Computer Model ◽  
Relative Velocity ◽  
Frequency Response Function ◽  
Usual Method ◽  
Theoretical Interest ◽  
Frequency Spectra ◽  
Computer Based ◽  
Vibrating Systems ◽  
Electrical Theory

If a frequency spectra or frequency response function is known for a structure what physical model can be generated to represent it? This is an important question for computer based simulations where a translation must be made between a spectra and a computer model. This is particularly difficult if damping is to be modelled. Investigation of electrical theory shows that this problem has been examined in detail due to the need to construct circuits that have specific spectra. However, before ideas can be borrowed from electrical theory it is necessary to develop vibration theory so that it aligns perfectly with electrical theory. To achieve this a method for representing mass is suggested which is a generalisation of the usual method and involves using a system of levers so that force is equal to mass times the derivative of relative velocity rather than absolute velocity. It is then shown that following electrical theory a damped spectra may be represented by an undamped sequence of masses and springs terminated by just one dashpot. Such a model is of considerable theoretical interest as well as having utility in computer simulations.

scholarly journals A Ship Domain-Based Method of Determining Action Distances for Evasive Manoeuvres in Stand-On Situations

2018 ◽  
Vol 2018 ◽  
pp. 1-19 ◽  
Author(s):  
Rafal Szlapczynski ◽  
Przemyslaw Krata ◽  
Joanna Szlapczynska
Keyword(s):  
Collision Avoidance ◽  
Weather Conditions ◽  
Dynamics Model ◽  
Speed Reduction ◽  
Avoidance Manoeuvre ◽  
Simulation Results ◽  
Exact Moment ◽  
Published Research

A ship encounter can be considered safe if neither of ships’ domains (defined areas around ships) is intruded by other ships. Published research on this includes optimising collision avoidance manoeuvres fulfilling domain-based safety conditions. However, until recently there was no method, using ship’s domain to determine exact moment when a particular collision avoidance manoeuvre can still be successfully performed. The authors have already proposed such method for give-way encounters. In the paper, documenting continuation of the research, another kind of scenarios is considered. This paper is focused on situations where the own ship is the stand-on one and the target is supposed to manoeuvre. The presented method uses a ship’s dynamics model to compute distance necessary for a manoeuvre successful in terms of avoiding domain violations. Additionally, stability-related phenomena and their impact on possible manoeuvres in heavy weather are taken into account. The method and applied models are illustrated in a series of simulation results. The simulations cover various examples of stand-on situations, including encounters in heavy weather conditions. Discussed manoeuvres may be limited to course alteration or may combine turns with speed reduction.

scholarly journals FFAU—Framework for Fully Autonomous UAVs

2020 ◽  
Vol 12 (21) ◽  
pp. 3533
Author(s):  
Dário Pedro ◽  
João P. Matos-Carvalho ◽  
Fábio Azevedo ◽  
Ricardo Sacoto-Martins ◽  
Luís Bernardo ◽  
...  
Keyword(s):  
Real Time ◽  
Collision Avoidance ◽  
New Technology ◽  
Experimental Tests ◽  
Urban Environments ◽  
Novel Approach ◽  
Safety Risks ◽  
Stationary Objects ◽  
Safety And Reliability ◽  
Remote Clients

Unmanned Aerial Vehicles (UAVs), although hardly a new technology, have recently gained a prominent role in many industries being widely used not only among enthusiastic consumers, but also in high demanding professional situations, and will have a massive societal impact over the coming years. However, the operation of UAVs is fraught with serious safety risks, such as collisions with dynamic obstacles (birds, other UAVs, or randomly thrown objects). These collision scenarios are complex to analyze in real-time, sometimes being computationally impossible to solve with existing State of the Art (SoA) algorithms, making the use of UAVs an operational hazard and therefore significantly reducing their commercial applicability in urban environments. In this work, a conceptual framework for both stand-alone and swarm (networked) UAVs is introduced, with a focus on the architectural requirements of the collision avoidance subsystem to achieve acceptable levels of safety and reliability. The SoA principles for collision avoidance against stationary objects are reviewed and a novel approach is described, using deep learning techniques to solve the computational intensive problem of real-time collision avoidance with dynamic objects. The proposed framework includes a web-interface allowing the full control of UAVs as remote clients with a supervisor cloud-based platform. The feasibility of the proposed approach was demonstrated through experimental tests using a UAV, developed from scratch using the proposed framework. Test flight results are presented for an autonomous UAV monitored from multiple countries across the world.

A Computer Simulation of Marine Traffic Using Domains and Arenas

1980 ◽  
Vol 33 (2) ◽  
pp. 215-222 ◽  
Author(s):  
P. V. Davis ◽  
M. J. Dove ◽  
C. T. Stockel
Keyword(s):  
Computer Simulation ◽  
Computer Model ◽  
Discrete Series ◽  
Effective Area ◽  
Traffic Flows ◽  
Routing Schemes ◽  
Traffic Routing ◽  
Marine Traffic ◽  
Stationary Objects

This paper outlines the concept of a domain and an evasion area, called an arena, around a ship which are then applied to produce a computer model of ship behaviour. The arena determines when a ship takes avoiding action, as does the land arena which reacts with a discrete series of coastal points to prevent the ship running aground.The increase in the number and size of ships has resulted in the introduction of traffic routing schemes and the need to understand ship behaviour more thoroughly. The concept of ‘the effective area around a ship which a navigator would like to keep clear with respect to other ships and stationary objects’ has been used by various authors including Goodwin, Fujii and Lewison with varying names such as domain, collision diameters and encounter area. There has been no fixed shape for these areas. Some are circular, others elliptical, while Goodwin's has three segments each with its own portion of a circle. By developing the theory of the domain, it was hoped to be able to produce a model of traffic behaviour which could be used to simulate traffic flows, or specific incidents, in order to study them more fully.

Mathematical modelling of sulphides and hydrogen sulphide gas build-up in the Costa do Estoril sewerage system

1995 ◽  
Vol 31 (7) ◽  
pp. 255-261 ◽  
Author(s):  
J. S. Matos ◽  
C. M. Aires
Keyword(s):  
Mathematical Model ◽  
Mathematical Modelling ◽  
Computer Model ◽  
Hydrogen Sulphide ◽  
Preventive Measures ◽  
Main Trunk ◽  
Sewerage System ◽  
Trunk Line ◽  
High Level

The Costa do Estoril sewerage system is one of the largest separate systems ever built in Portugal. Because of the quality of the environment in the region and the high level of touristic use, special care was given, in its design, to sulphide calculations. This paper describes the application to the Costa do Estoril sewerage system of an integrated computer model for forecasting sulphides and hydrogen sulphide gas build-up along sewer atmospheres. The empirical sulphide prediction equations have been calibrated with experimental results obtained under a research project carried out in a gravity tributary and in a rising main located near the Costa do Estoril zone. The hydrogen sulphide gas concentrations along the main trunk line have been predicted according to an mathematical model described by Matos and Sousa. The results of the model have been considered to be adequate for identifying critical reaches and for predicting the effects of corrective and preventive measures on the overall behaviour of the system.

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