A novel functional link network stacking ensemble with fractal features for multichannel fall detection

Ahsen Tahir*, Gordon Morison, Dawn A. Skelton, Ryan Gibson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
63 Downloads (Pure)


Falls are a major health concern and result in high morbidity and mortality rates in older adults with high costs to health services. Automatic fall classification and detection systems can provide early detection of falls and timely medical aid. This paper proposes a novel Random Vector Functional Link (RVFL) stacking ensemble classifier with fractal features for classification of falls. The fractal Hurst exponent is used as a representative of fractal dimensionality for capturing irregularity of accelerometer signals for falls and other activities of daily life. The generalised Hurst exponents along with wavelet transform coefficients are leveraged as input feature space for a novel stacking ensemble of RVFLs composed with an RVFL neural network meta-learner. Novel fast selection criteria are presented for base classifiers founded on the proposed diversity indicator, obtained from the overall performance values during the training phase. The proposed features and the stacking ensemble provide the highest classification accuracy of 95.71% compared with other machine learning techniques, such as Random Forest (RF), Artificial Neural Network (ANN) and Support Vector Machine. The proposed ensemble classifier is 2.3× faster than a single Decision Tree and achieves the highest speedup in training time of 317.7× and 198.56× compared with a highly optimised ANN and RF ensemble, respectively. The significant improvements in training times of the order of 100× and high accuracy demonstrate that the proposed RVFL ensemble is a prime candidate for real-time, embedded wearable device–based fall detection systems.
Original languageEnglish
Pages (from-to)1024-1042
Number of pages19
JournalCognitive Computation
Issue number5
Publication statusPublished - 29 Jul 2020


  • artificial neural network
  • ensemble learning
  • fall detection
  • fractal features
  • machine learning
  • RVFL neural network


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