To Örebro University

oru.seÖrebro University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Towards Dense Air Quality Monitoring: Time-Dependent Statistical Gas Distribution Modelling and Sensor Planning
Örebro University, School of Science and Technology.
2017 (English)Doctoral thesis, monograph (Other academic)
Abstract [en]

This thesis addresses the problem of gas distribution modelling for gas monitoring and gas detection. The presented research is particularly focused on the methods that are suitable for uncontrolled environments. In such environments, gas source locations and the physical properties of the environment, such as humidity and temperature may be unknown or only sparse noisy local measurements are available. Example applications include air pollution monitoring, leakage detection, and search and rescue operations.

This thesis addresses how to efficiently obtain and compute predictive models that accurately represent spatio-temporal gas distribution.

Most statistical gas distribution modelling methods assume that gas dispersion can be modelled as a time-constant random process. While this assumption may hold in some situations, it is necessary to model variations over time in order to enable applications of gas distribution modelling for a wider range of realistic scenarios.

This thesis proposes two time-dependent gas distribution modelling methods. In the first method, a temporal (sub-)sampling strategy is introduced. In the second method, a time-dependent gas distribution modelling approach is presented, which introduces a recency weight that relates measurement to prediction time. These contributions are presented and evaluated as an extension of a previously proposed method called Kernel DM+V using several simulation and real-world experiments. The results of comparing the proposed time-dependent gas distribution modelling approaches to the time-independent version Kernel DM+V indicate a consistent improvement in the prediction of unseen measurements, particularly in dynamic scenarios under the condition that there is a sufficient spatial coverage. Dynamic scenarios are often defined as environments where strong fluctuations and gas plume development are present.

For mobile robot olfaction, we are interested in sampling strategies that provide accurate gas distribution models given a small number of samples in a limited time span. Correspondingly, this thesis addresses the problem of selecting the most informative locations to acquire the next samples.

As a further contribution, this thesis proposes a novel adaptive sensor planning method. This method is based on a modified artificial potential field, which selects the next sampling location based on the currently predicted gas distribution and the spatial distribution of previously collected samples. In particular, three objectives are used that direct the sensor towards areas of (1) high predictive mean and (2) high predictive variance, while (3) maximising the coverage area. The relative weight of these objectives corresponds to a trade-off between exploration and exploitation in the sampling strategy. This thesis discusses the weights or importance factors and evaluates the performance of the proposed sampling strategy. The results of the simulation experiments indicate an improved quality of the gas distribution models when using the proposed sensor planning method compared to commonly used methods, such as random sampling and sampling along a predefined sweeping trajectory. In this thesis, we show that applying a locality constraint on the proposed sampling method decreases the travelling distance, which makes the proposed sensor planning approach suitable for real-world applications where limited resources and time are available. As a real-world use-case, we applied the proposed sensor planning approach on a micro-drone in outdoor experiments.

Finally, this thesis discusses the potential of using gas distribution modelling and sensor planning in large-scale outdoor real-world applications. We integrated the proposed methods in a framework for decision-making in hazardous inncidents where gas leakage is involved and applied the gas distribution modelling in two real-world use-cases. Our investigation indicates that the proposed sensor planning and gas distribution modelling approaches can be used to inform experts both about the gas plume and the distribution of gas in order to improve the assessment of an incident.

Place, publisher, year, edition, pages
Örebro: Örebro University , 2017. , p. 145
Series
Örebro Studies in Technology, ISSN 1650-8580 ; 77
Keywords [en]
mobile robot olfaction, time-dependent gas distribution modelling, temporal sub-sampling, sensor planning, artificial potential field, gas monitoring
National Category
Computer Sciences
Identifiers
URN: urn:nbn:se:oru:diva-61113ISBN: 978-91-7529-214-4 (print)OAI: oai:DiVA.org:oru-61113DiVA, id: diva2:1143518
Public defence
2017-11-17, Örebro universitet, Långhuset, Hörsal 2, Fakultetsgatan 1, Örebro, 13:15 (English)
Opponent
Supervisors
Available from: 2017-09-21 Created: 2017-09-21 Last updated: 2018-01-13Bibliographically approved

Open Access in DiVA

Cover(176 kB)161 downloads
File information
File name COVER01.pdfFile size 176 kBChecksum SHA-512
b68b3c456e61164afc378fd48ea38290a5cef682e85c81977848b863326d2d5c22082d75811711f12f592ada5bd675a7d673ea7470c720f598d2faf0db70e66b
Type coverMimetype application/pdf
Spikblad(111 kB)112 downloads
File information
File name SPIKBLAD01.pdfFile size 111 kBChecksum SHA-512
e5b95c13e38d05624c99c7d4a1a1b919fd56493e69b5b770b0834e644f8543d8b75851fc85a27d4e3c9391e3d303bd47d13b5eef0428d376b5634be966bd2dd3
Type spikbladMimetype application/pdf
Towards Dense Air Quality Monitoring: Time-Dependent Statistical Gas Distribution Modelling and Sensor Planning(21134 kB)847 downloads
File information
File name FULLTEXT02.pdfFile size 21134 kBChecksum SHA-512
ef5d5d7da61be15eee80354947db7cdb81b03600992be264833ad91d500e0eb833970a84d47642881262bd218a9aa96d682c9f0d737a79037b13235d030bffd4
Type fulltextMimetype application/pdf

Authority records

Asadi, Sahar

Search in DiVA

By author/editor
Asadi, Sahar
By organisation
School of Science and Technology
Computer Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 847 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 998 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf