scholarly journals Online planning low-cost paths for unmanned surface vehicles based on the artificial vector field and environmental heuristics

2020 ◽  
Vol 17 (6) ◽  
pp. 172988142096907
Author(s):  
Naifeng Wen ◽  
Rubo Zhang ◽  
Guanqun Liu ◽  
Junwei Wu ◽  
Xingru Qu
Keyword(s):  
Vector Field ◽  
Low Cost ◽  
Field Method ◽  
Collision Probability ◽  
Sampling Scheme ◽  
Unmanned Surface Vehicles ◽  
Online Planning ◽  
Cost Paths ◽  
Virtual Leader ◽  
Gaussian Sampling

The study is concerned with the problem of online planning low-cost cooperative paths; those are energy-efficient, easy-to-execute, and low collision probability for unmanned surface vehicles (USVs) based on the artificial vector field and environmental heuristics. First, we propose an artificial vector field method by following the global optimally path and the current to maximize the known environmental information. Then, to improve the optimal rapidly exploring random tree (RRT*) based planner by the environment heuristics, a Gaussian sampling scheme is adopted to seek for the likely samples that locate near obstacles. Meanwhile, a multisampling strategy is proposed to choose low-cost path tree extensions locally. The vector field guidance, the Gaussian sampling scheme, and the multisampling strategy are used to improve the efficiency of RRT* to obtain a low-cost path for the virtual leader of USVs. To promote the accuracy of collision detection during the execution process of RRT*, an ellipse function-based bounding box for USVs is proposed with the consideration of the current. Finally, an information consensus scheme is employed to quickly calculate cooperative paths for a fleet of USVs guided by the virtual leader. Simulation results show that our online cooperative path planning method is performed well in the practical marine environment.

scholarly journals Modified Vector Field Path-Following Control System for an Underactuated Autonomous Surface Ship Modelin the Presence of Static Obstacles

2021 ◽  
Vol 9 (6) ◽  
pp. 652
Author(s):  
Haitong Xu ◽  
Miguel A. Hinostroza ◽  
C. Guedes Guedes Soares
Keyword(s):  
Control System ◽  
Vector Field ◽  
Path Following ◽  
Field Method ◽  
Integrated System ◽  
Ship Model ◽  
Surface Ship ◽  
Path Following Control ◽  
Exponentially Stable ◽  
Vector Field Method

A modified path-following control system using the vector field method for an underactuated autonomous surface ship model is proposed in the presence of static obstacles. With this integrated system, autonomous ships are capable of following the predefined path, while avoiding the obstacles automatically. It is different from the methods in most published papers, which usually study path-following and obstacle collision avoidance, separately. This paper considers the coupled path following and collision avoidance task as a whole. Meanwhile, the paper also shows the heading control design method in the presence of static obstacles. To obtain a strong stability property, a nonlinear autopilot is designed based on the manoeuvring tests of the free-running ship model. The equilibrium point of the controller is globally exponentially stable. For the guidance system, a novel vector field method was proposed, and the proof shows the coupled guidance and control system is uniform semi-global exponentially stable (USGES). To prevent the obstacles near the predefined path, the proposed guidance law is augmented by integrating the repelling field of obstacles so that it can control the ship travel toward the predefined path through the obstacles safely. The repelling field function is given considering the obstacle shape and collision risk using the velocity obstacle (VO) algorithm. The simulations and ship model test were performed to validate the integrated system of autonomous ships.

scholarly journals A vector field method for relativistic transport equations with applications

2017 ◽  
Vol 10 (7) ◽  
pp. 1539-1612 ◽  
Author(s):  
David Fajman ◽  
Jérémie Joudioux ◽  
Jacques Smulevici
Keyword(s):  
Vector Field ◽  
Field Method ◽  
Transport Equations ◽  
Vector Field Method

Auxiliary-Field Method for Vector Field Theories

1966 ◽  
Vol 145 (4) ◽  
pp. 1171-1176 ◽  
Author(s):  
Bibhuti Bhusan Deo
Keyword(s):  
Vector Field ◽  
Field Method ◽  
Auxiliary Field ◽  
Field Theories

scholarly journals Time and Covariance Threshold Triggered Optimal Uncooperative Rendezvous Using Angles-Only Navigation

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Yue You ◽  
Hua Wang ◽  
Christophe Paccolat ◽  
Volker Gass ◽  
Jean-Philippe Thiran ◽  
...  
Keyword(s):  
Relative Position ◽  
Relative Velocity ◽  
Unscented Kalman Filter ◽  
Low Cost ◽  
Power Saving ◽  
Planning Method ◽  
Collision Probability ◽  
Analysis Model ◽  
Relative State ◽  
State Estimations

A time and covariance threshold triggered optimal maneuver planning method is proposed for orbital rendezvous using angles-only navigation (AON). In the context of Yamanaka-Ankersen orbital relative motion equations, the square root unscented Kalman filter (SRUKF) AON algorithm is developed to compute the relative state estimations from a low-volume/mass, power saving, and low-cost optical/infrared camera’s observations. Multi-impulsive Hill guidance law is employed in closed-loop linear covariance analysis model, based on which the quantitative relative position robustness and relative velocity robustness index are defined. By balancing fuel consumption, relative position robustness, and relative velocity robustness, we developed a time and covariance threshold triggered two-level optimal maneuver planning method, showing how these results correlate to past methods and missions and how they could potentially influence future ones. Numerical simulation proved that it is feasible to control the spacecraft with a two-line element- (TLE-) level uncertain, 34.6% of range, initial relative state to a 100 m v-bar relative station keeping point, at where the trajectory dispersion reduces to 3.5% of range, under a 30% data gap per revolution on account of the eclipse. Comparing with the traditional time triggered maneuver planning method, the final relative position accuracy is improved by one order and the relative trajectory robustness and collision probability are obviously improved and reduced, respectively.

scholarly journals Separating equilibria in continuous signalling games

2002 ◽  
Vol 357 (1427) ◽  
pp. 1595-1606 ◽  
Author(s):  
Carl T. Bergstrom ◽  
Szabolcs Számadó ◽  
Michael Lachmann
Keyword(s):  
Vector Field ◽  
Solution Method ◽  
Low Cost ◽  
Minimal Cost ◽  
Field Solution ◽  
Signalling Theory ◽  
Conflicting Interests ◽  
Mathematical Justification ◽  
Signalling Games

Much of the literature on costly signalling theory concentrates on separating equilibria of continuous signalling games. At such equilibria, every signaller sends a distinct signal, and signal receivers are able to exactly infer the signaller's condition from the signal sent. In this paper, we introduce a vector–field solution method that simplifies the process of solving for separating equilibria. Using this approach, we show that continuous signalling games can have low–cost separating equilibria despite conflicting interests between signaller and receiver. We find that contrary to prior arguments, honesty does not require wasteful signals. Finally, we examine signalling games in which different signallers have different minimal–cost signals, and provide a mathematical justification for the argument that even non–signalling traits will be exaggerated beyond their phenotypic optimum when they are used by other individuals to judge condition or quality.

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