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Unsupervised learning of sensor topologies for improving activity recognition in smart environments

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)93-106
Number of pages13
Early online date22 Dec 2016
DateAccepted/In press - 19 Dec 2016
DateE-pub ahead of print - 22 Dec 2016
DatePublished (current) - 19 Apr 2017


There has been significant recent interest in sensing systems and ‘smart environments’, with a number of longitudinal studies in this area. Typically the goal of these studies is to develop methods to predict, at any one moment of time, the activity or activities that the resident(s) of the home are engaged in, which may in turn be used for determining normal or abnormal patterns of behaviour (e.g. in a health-care setting). Classification algorithms, such as Conditional Random Field (CRFs), typically consider sensor activations as features but these are often treated as if they were independent, which in general they are not. Our hypothesis is that learning patterns based on combinations of sensors will be more powerful than single sensors alone. The exhaustive approach – to take all possible combinations of sensors and learn classifier weights for each combination – is clearly computationally prohibitive. We show that through the application of signal processing and information-theoretic techniques we can learn about the sensor topology in the home (i.e. learn an adjacency matrix) which enables us to determine the combinations of sensors that will be useful for classification ahead of time. As a result we can achieve classification performance better than that of the exhaustive approach, whilst only incurring a small cost in terms of computational resources. We demonstrate our results on several datasets, showing that our method is robust in terms of variations in the layout and the number of residents in the house. Furthermore, we have incorporated the adjacency matrix into the CRF learning framework and have shown that it can improve performance over multiple baselines.

    Research areas

  • Activities of daily life, Activity recognition, Digital signal processing, Machine learning, Meta learning, Smart homes, Unsupervised learning, Digital Health

    Structured keywords

  • Jean Golding
  • Digital Health

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    Rights statement: This is the author accepted manuscript (AAM). The final published version (version of record) is available online via Elsevier at Please refer to any applicable terms of use of the publisher.

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    Licence: CC BY-NC-ND


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