Damien O’Rourke

Cambridge Consultants (United Kingdom)

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Tim Wark

Data61

Junbin Liu

Chinese University of Hong Kong

Conor Brennan

Dublin City University

Wen Hu

UNSW Sydney

Darren Moore

LASALLE College of the Arts

Sridha Sridharan

Queensland University of Technology

John Almond

Seoul National University

Hannah Kilroy

Clarity Centre for Sensor Web Technologies

Simon Denman

Queensland University of Technology

Alberto Zaffaroni

Clarity Centre for Sensor Web Technologies

Cooperative Institutions

Clarity Centre for Sensor Web Technologies

Queensland University of Technology

Commonwealth Scientific and Industrial Research Organisation

Cambridge Consultants (United Kingdom)

University College Dublin

University of Queensland

Data61

Health Sciences and Nutrition

Dublin City University

Charité - Universitätsmedizin Berlin

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3D Colour vision for machine automation and safety – AI Sensor Fusion

VDI Verlag eBooks (2020)

Sara R. Jordan Damien O’Rourke Lori Avery John Almond

Machine Vision

Sensor Fusion

10.51202/9783181023747-345

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Citations (1)

On packet combining for wireless sensor networks

China-Ireland International Conference on Information and Communications Technologies (CIICT 2008) (2008)

Damien O’Rourke Conor Brennan

Packet combining has been shown to be of benefit for WSNs. However, most of the approaches used to determine its effectiveness are optimal in some sense and it is not clear whether or not more simple forms of packet combining for use on low power Wireless Sensor Networks complying with, for example, the IEEE 802.15.4 standard are of benefit. This paper shows simulation results of the SNR gain and diversity gain when using a simple form of packet combining known as packet merging in both cooperative and non-cooperative scenarios. Some of the issues regarding packet merging are discussed also which include practical results regarding hidden errors.

Diversity gain

Packet forwarding

10.1049/cp:20080859

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Reception region characterisation using a 2.4GHz direct sequence spread spectrum radio

Damien O’Rourke Szymon Fedor Conor Brennan Martin Collier

Experimental studies on Wireless Sensor Networks (WSNs) have revealed the existence of three distinct reception regions. These regions can be classified as connected, transitional, and disconnected. Their location and size may have a significant impact on the performance of communication protocols. The underlying causes for the transitional (or so-called "grey") region have been determined in previous work using both analytical and empirical techniques. Conclusions drawn from these experiments suggest that the transitional region is caused in part by multi-path fading. A natural assumption therefore is that any system used to combat multipath effects will also reduce the extent of the transitional region. Measurements from previous works were mainly carried out on radio architectures using (for example) NRZ and noncoherent FSK and therefore do not validate this assumption. This work shows that the above hypothesis is invalid due to a smaller decay factor and increased standard deviation of the shadowing component for high mulit-path environments. Along with the usual Packet Reception Rate (PRR) tests, a BER test was also undertaken to help identify and characterise the transitional region. A side result of this is that the measured BER shows some deviation from the theoretical value given in the IEEE 802.15.4 standard and provides evidence why RSSI may not be a good link quality estimator in certain circumstances. In addition a number of practical issues encountered and resolved are reported in the paper.

10.1145/1278972.1278990

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Citations (9)

Propfan test assessment propfan propulsion system static test report

Damien O’Rourke

The propfan test assessment (PTA) propulsion system successfully completed over 50 hours of extensive static ground tests, including a 36 hour endurance test. All major systems performed as expected, verifying that the large-scale 2.74 m diameter propfan, engine, gearbox, controls, subsystems, and flight instrumentation will be satisfactory with minor modifications for the upcoming PTA flight tests on the GII aircraft in early 1987. A test envelope was established for static ground operation to maintain propfan blade stresses within limits for propfan rotational speeds up to 105 percent and power levels up to 3880 kW. Transient tests verified stable, predictable response of engine power and propfan speed controls. Installed engine TSFC was better than expected, probably due to the excellent inlet performance coupled with the supercharging effect of the propfan. Near- and far-field noise spectra contained three dominant components, which were dependent on power, tip speed, and direction. The components were propfan blade tones, propfan random noise, and compressor/propfan interaction noise. No significant turbine noise or combustion noise was evident.

Instrumentation

Flight test

Flight envelope

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Practical packet combining for use with cooperative and non-cooperative ARQ schemes in resource-constrained wireless sensor networks

Ad Hoc Networks (2011)

Damien O’Rourke Conor Brennan

Selective Repeat ARQ

Go-Back-N ARQ

10.1016/j.adhoc.2011.06.013

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Citations (11)

Camera calibration in wireless multimedia sensor networks

Junbin Liu Damien O’Rourke Tim Wark Ruan Lakemond Sridha Sridharan

Wireless multimedia sensor networks (WMSNs) have become increasingly popular in recent years, driven in part by the increasing commoditization of small, low-cost CMOS sensors. As such, the challenge of automatically calibrating these types of cameras nodes has become an important research problem, especially for the case when a large quantity of these type of devices are deployed. This paper presents a method for automatically calibrating a wireless camera node with the ability to rotate around one axis. The method involves capturing images as the camera is rotated and computing the homographies between the images. The camera parameters, including focal length, principal point and the angle and axis of rotation can then recovered from two or more homographies. The homography computation algorithm is designed to deal with the limited resources of the wireless sensor and to minimize energy consumption. In this paper, a modified RANdom SAmple Consensus (RANSAC) algorithm is proposed to effectively increase the efficiency and reliability of the calibration procedure.

RANSAC

Homography

CMOS Sensor

10.1109/issnip.2009.5416797

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Citations (6)

An Energy-efficient Rate Adaptive Media Access Protocol (RA-MAC) for Long-lived Sensor Networks

Sensors (2010)

Wen Hu Quanjun Chen Peter Corke Damien O’Rourke

We introduce an energy-efficient Rate Adaptive Media Access Control (RA-MAC) algorithm for long-lived Wireless Sensor Networks (WSNs). Previous research shows that the dynamic and lossy nature of wireless communications is one of the major challenges to reliable data delivery in WSNs. RA-MAC achieves high link reliability in such situations by dynamically trading off data rate for channel gain. The extra gain that can be achieved reduces the packet loss rate which contributes to reduced energy expenditure through a reduced numbers of retransmissions. We achieve this at the expense of raw bit rate which generally far exceeds the application’s link requirement. To minimize communication energy consumption, RA-MAC selects the optimal data rate based on the estimated link quality at each data rate and an analytical model of the energy consumption. Our model shows how the selected data rate depends on different channel conditions in order to minimize energy consumption. We have implemented RA-MAC in TinyOS for an off-the-shelf sensor platform (the TinyNode) on top of a state-of-the-art WSN Media Access Control Protocol, SCP-MAC, and evaluated its performance by comparing our implementation with the original SCP-MAC using both simulation and experiment.

Media access control

10.3390/s100605548

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A distributed protocol for object tracking in wireless multimedia sensor networks

Junbin Liu Damien O’Rourke Tim Wark Simon Denman Sridha Sridharan

We consider the problem of object tracking in a wireless multimedia sensor network (we mainly focus on the camera component in this work). The vast majority of current object tracking techniques, either centralised or distributed, assume unlimited energy, meaning these techniques don't translate well when applied within the constraints of low-power distributed systems. In this paper we develop and analyse a highly-scalable, distributed strategy to object tracking in wireless camera networks with limited resources. In the proposed system, cameras transmit descriptions of objects to a subset of neighbours, determined using a predictive forwarding strategy. The received descriptions are then matched at the next camera on the objects path using a probability maximisation process with locally generated descriptions. We show, via simulation, that our predictive forwarding and probabilistic matching strategy can significantly reduce the number of object-misses, ID-switches and ID-losses; it can also reduce the number of required transmissions over a simple broadcast scenario by up to 67%. We show that our system performs well under realistic assumptions about matching objects appearance using colour.

Tracking (education)

Component (thermodynamics)

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A Practical Implementation of an Improved Packet Combining Scheme for Wireless Sensor Networks

Damien O’Rourke Conor Brennan

An improvement to a recently proposed packet combining procedure based on the use of a CRC is developed. Upon receiving two packets, sent over independent channels, a large error burst may appear in one; however, it is unlikely that the same situation will have occurred for its pair. By making an intelligent choice as to which packet the burst is most likely to be in, and choosing the other packet for correction, the decoding time can be reduced significantly. A practical implementation is provided with real results that show not only can this decision be made correctly on the majority of occasions but, once the correct packet is chosen, an intelligent search operation can be performed further reducing overhead.

Fast packet switching

Packet analyzer

Packet generator

Packet loss

10.1109/iccw.2008.69

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Citations (4)

Two-wavelength holography for non-line-of-sight imaging

John Almond Thomas Watson Damien O’Rourke Ermes Tonellini McGregor Clayton

Emerging techniques for imaging around corners and through scattering media hold promise for visualizing hidden scenes in challenging situations. Synthetic Wavelength Holography (SWH) is one of these techniques, which appears to offer key advantages compared to alternative approaches. However, a critical analysis of the approach is currently lacking. Here we present our findings as to the capabilities of a nanosecond pulsed, short wavelength infrared SWH system we have built and compare these with theory. We also discuss practical aspects of deploying this technology.

Line-of-sight

Non-line-of-sight propagation

10.1117/12.3031710

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