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

Niall Twomey*, Tom Diethe, Ian Craddock, Peter Flach

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

22 Citations (Scopus)
410 Downloads (Pure)


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.
Original languageEnglish
Pages (from-to)93-106
Number of pages14
Early online date22 Dec 2016
Publication statusPublished - 19 Apr 2017

Structured keywords

  • Jean Golding
  • Digital Health


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


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