Intruder capture algorithms considering visible intruders

In this article, we consider the problem of using multiple robots (searchers) to capture intruders in an environment. Assume that a robot can access the position of an intruder in real time, that is, an intruder is visible by a robot. We simplify the environment so that robots and worst-case intruders move along a weighted graph, which is a topological map of the environment. In such settings, a worst-case intruder is characterized by unbounded speed, complete awareness of searcher location and intent, and full knowledge of the search environment. The weight of an edge or a vertex in a weighted graph is a cost describing the clearing requirement of the edge or the vertex. This article provides non-monotone search algorithms to capture every visible intruder. Our algorithms are easy to implement, thus are suitable for practical robot applications. Based on the non-monotone search algorithms, we derive the minimum number of robots required to clear a weighted tree graph. Considering a general weighted graph, we derive bounds for the number of robots required. Finally, we present switching algorithms to improve the time efficiency of capturing intruders while not increasing the number of robots. We verify the effectiveness of our approach using MATLAB simulations.

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Workspace exploration and protection with multiple robots assisted by sensor networks

International Journal of Advanced Robotic Systems ◽

10.1177/1729881418792170 ◽

2018 ◽

Vol 15 (4) ◽

pp. 172988141879217 ◽

Cited By ~ 5

Author(s):

Jonghoek Kim

Keyword(s):

Sensor Network ◽

Voronoi Diagram ◽

Dual Graph ◽

Upper Bounds ◽

Sensor Nodes ◽

Multiple Robots ◽

Global Localization ◽

Topological Map ◽

Minimum Number ◽

Exchange Data

This article introduces multi-robot strategies making multiple robots explore an unknown environment in a cooperative manner. Our exploration strategies do not require global localization of a robot or a node. Multiple robots build a Voronoi diagram as a topological map of the environment, while deploying sensor nodes which can sense and communicate. As the sensor network built by one robot meets the network built by another robot, both robots can exchange data with each other. The robots then use the merged sensor network to protect the environment. We introduce an intruder capture algorithm assuming that a robot is able to access any intruder’s location utilizing the sensor network. This algorithm is robust to time delay in information sharing utilizing the sensor network. Utilizing the algorithm, we derive upper bounds on the number of robots needed to capture every intruder in the environment. This article proves that the minimum number of robots needed can be computed by finding proper edge covers of the dual graph of the Voronoi diagram.

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Capturing intruders based on Voronoi diagrams assisted by information networks

International Journal of Advanced Robotic Systems ◽

10.1177/1729881416682693 ◽

2017 ◽

Vol 14 (1) ◽

pp. 172988141668269 ◽

Cited By ~ 6

Author(s):

Jonghoek Kim

Keyword(s):

Time Delay ◽

Voronoi Diagram ◽

Data Transfer ◽

Information Networks ◽

Information Network ◽

Multiple Robots ◽

Topological Map ◽

General Graph ◽

Maximum Range ◽

Minimum Number

We consider a scenario of deploying multiple robots to capture all intruders in a cluttered workspace with many obstacles. Here, we say that a robot captures an intruder in the case where the intruder is within the maximum range of a weapon on the robot. All robots use the Voronoi diagram as the topological map of the workspace. Due to obstacles, intruders are confined to move along a passage between obstacles. Suppose the weapons on every robot are powerful enough to cover a passage in the workspace. Then, we can consider a simplified scenario such that robots and intruders are restricted to stay on the Voronoi diagram. We assume that a robot can detect the position of any intruder using the information network. This article presents an intruder capturing strategy that is robust to time delay in data transfer using the network. Our strategy does not require the localization of a node or a robot. Based on this strategy, we provide an upper bound for the minimum number of robots required to capture all intruders on a general graph, which leads to a result of the Voronoi diagram. Lastly, we provide MATLAB (version 7.10.0 R2010a) simulations to verify the effectiveness of our capturing strategy.

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Front-to-End Bidirectional Heuristic Search with Near-Optimal Node Expansions

Proceedings of the Twenty-Sixth International Joint Conference on Artificial Intelligence ◽

10.24963/ijcai.2017/69 ◽

2017 ◽

Cited By ~ 5

Author(s):

Jingwei Chen ◽

Robert C. Holte ◽

Sandra Zilles ◽

Nathan R. Sturtevant

Keyword(s):

Heuristic Search ◽

Search Algorithm ◽

Optimal Solution ◽

Search Algorithms ◽

Worst Case ◽

Heuristic Search Algorithm ◽

Bidirectional Search ◽

Optimal Node ◽

Minimum Number ◽

Better Than

It is well-known that any admissible unidirectional heuristic search algorithm must expand all states whose f-value is smaller than the optimal solution cost when using a consistent heuristic. Such states are called “surely expanded” (s.e.). A recent study characterized s.e. pairs of states for bidirectional search with consistent heuristics: if a pair of states is s.e. then at least one of the two states must be expanded. This paper derives a lower bound, VC, on the minimum number of expansions required to cover all s.e. pairs, and present a new admissible front-to-end bidirectional heuristic search algorithm, Near-Optimal Bidirectional Search (NBS), that is guaranteed to do no more than 2VC expansions. We further prove that no admissible front-to-end algorithm has a worst case better than 2VC. Experimental results show that NBS competes with or outperforms existing bidirectional search algorithms, and often outperforms A* as well.

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Network Calculus-Based Latency for Time-Triggered Traffic under Flexible Window-Overlapping Scheduling (FWOS) in a Time-Sensitive Network (TSN)

Applied Sciences ◽

10.3390/app11093896 ◽

2021 ◽

Vol 11 (9) ◽

pp. 3896

Author(s):

Khaled M. Shalghum ◽

Nor Kamariah Noordin ◽

Aduwati Sali ◽

Fazirulhisyam Hashim

Keyword(s):

Real Time ◽

Connected Vehicles ◽

Network Calculus ◽

Timing Constraints ◽

Traffic Scheduling ◽

Worst Case ◽

Continuous Increase ◽

Scheduled Traffic ◽

Support Time ◽

New Framework

Deterministic latency is an urgent demand to pursue the continuous increase in intelligence in several real-time applications, such as connected vehicles and automation industries. A time-sensitive network (TSN) is a new framework introduced to serve these applications. Several functions are defined in the TSN standard to support time-triggered (TT) requirements, such as IEEE 802.1Qbv and IEEE 802.1Qbu for traffic scheduling and preemption mechanisms, respectively. However, implementing strict timing constraints to support scheduled traffic can miss the needs of unscheduled real-time flows. Accordingly, more relaxed scheduling algorithms are required. In this paper, we introduce the flexible window-overlapping scheduling (FWOS) algorithm that optimizes the overlapping among TT windows by three different metrics: the priority of overlapping, the position of overlapping, and the overlapping ratio (OR). An analytical model for the worst-case end-to-end delay (WCD) is derived using the network calculus (NC) approach considering the relative relationships between window offsets for consecutive nodes and evaluated under a realistic vehicle use case. While guaranteeing latency deadline for TT traffic, the FWOS algorithm defines the maximum allowable OR that maximizes the bandwidth available for unscheduled transmission. Even under a non-overlapping scenario, less pessimistic latency bounds have been obtained using FWOS than the latest related works.

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Real-time estimating spatial configuration between multiple robots by triangle and enumeration constraints

Proceedings. 2000 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2000) (Cat. No.00CH37113) ◽

10.1109/iros.2000.895272 ◽

2002 ◽

Cited By ~ 1

Author(s):

T. Nakamura ◽

A. Ebina ◽

M. Imai ◽

T. Ogasawara ◽

H. Ishiguro

Keyword(s):

Real Time ◽

Spatial Configuration ◽

Multiple Robots

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Language models and search algorithms for real-time speech recognition

International Journal of Man-Machine Studies ◽

10.1016/s0020-7373(85)80016-x ◽

1985 ◽

Vol 22 (5) ◽

pp. 523-547 ◽

Cited By ~ 7

Author(s):

Carlo Scagliola

Keyword(s):

Speech Recognition ◽

Real Time ◽

Search Algorithms ◽

Language Models

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Motion Estimation Architecture Using Efficient Adder-Compressors for HDTV Video Coding

Journal of Integrated Circuits and Systems ◽

10.29292/jics.v5i1.312 ◽

2010 ◽

Vol 5 (1) ◽

pp. 78-88 ◽

Cited By ~ 1

Author(s):

Marcelo Porto ◽

André Silva ◽

Sergo Almeida ◽

Eduardo Da Costa ◽

Sergio Bampi

Keyword(s):

Motion Estimation ◽

Real Time ◽

Search Algorithm ◽

Absolute Difference ◽

High Definition ◽

Case Processing ◽

Worst Case ◽

Average Case ◽

High Definition Television ◽

Internal Structures

This paper presents real time HDTV (High Definition Television) architecture for Motion Estimation (ME) using efficient adder compressors. The architecture is based on the Quarter Sub-sampled Diamond Search algorithm (QSDS) with Dynamic Iteration Control (DIC) algorithm. The main characteristic of the proposed architecture is the large amount of Processing Units (PUs) that are used to calculate the SAD (Sum of Absolute Difference) metric. The internal structures of the PUs are composed by a large number of addition operations to calculate the SADs. In this paper, efficient 4-2 and 8-2 adder compressors are used in the PUs architecture to achieve the performance to work with HDTV (High Definition Television) videos in real time at 30 frames per second. These adder compressors enable the simultaneous addition of 4 and 8 operands respectively. The PUs, using adder compressors, were applied to the ME architecture. The implemented architecture was described in VHDL and synthesized to FPGA and, with Leonardo Spectrum tool, to the TSMC 0.18μm CMOS standard cell technology. Synthesis results indicate that the new QSDS-DIC architecture reach the best performance result and enable gains of 12% in terms of processing rate. The architecture can reach real time for full HDTV (1920x1080 pixels) in the worst case processing 65 frames per second, and it can process 269 HDTV frames per second in the average case.

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Detection of Yeast-like Symbionts in Brown Planthopper Reared on Different Resistant Rice Varieties Combining DGGE and Absolute Quantitative Real-Time PCR

Insects ◽

10.3390/insects13010085 ◽

2022 ◽

Vol 13 (1) ◽

pp. 85

Author(s):

Chengling Lai ◽

Yun Hou ◽

Peiying Hao ◽

Kun Pang ◽

Xiaoping Yu

Keyword(s):

Real Time ◽

Real Time Pcr ◽

Brown Planthopper ◽

Nilaparvata Lugens ◽

Quantitative Real Time Pcr ◽

Nymphal Instar ◽

Rice Varieties ◽

Development Stages ◽

The Third ◽

Minimum Number

The brown planthopper (BPH), Nilaparvata lugens, is a serious pest of rice throughout Asia. Yeast-like symbionts (YLS) are endosymbionts closely linked with the development of BPH and the adapted mechanism of BPH virulence to resistant plants. In this study, we used semi-quantitative DGGE and absolute quantitative real-time PCR (qPCR) to quantify the number of the three YLS strains (Ascomycetes symbionts, Pichia-like symbionts, and Candida-like symbionts) that typically infect BPH in the nymphal stages and in newly emerged female adults. The quantities of each of the three YLS assessed increased in tandem with the developing nymphal instar stages, peaking at the fourth instar stage, and then declined significantly at the fifth instar stage. However, the amount of YLS present recovered sharply within the emerging adult females. Additionally, we estimated the quantities of YLS for up to eight generations after their inoculation onto resistant cultivars (Mudgo, ASD7, and RH) to reassociate the dynamics of YLS with the fitness of BPH. The minimum number of each YLS was detected in the second generation and gradually increased from the third generation with regard to resistant rice varieties. In addition, the Ascomycetes symbionts of YLS were found to be the most abundant of the three YLS strains tested for all of the development stages of BPH.

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