Shift-Adaptive Estimation of Joint Angle Using Instrumented Brace with Two Stretch Sensors Based on Gaussian Mixture Models

Ryo Eguchi, Brendan Michael, Matthew Howard, Masaki Takahashi

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Wearable motion sensing in daily life has attracted attention in various disciplines. Especially, stretchable strain sensors have been instrumented into garments (e.g. brace). To estimate joint motions from such sensors, previous studies have modelled relationships between the sensor strains and motion parameters via supervised/semi-supervised learning. However, typically these only model a single relationship assuming the sensor to be located at a specific point on the body. Consequently, they exhibit reduced performance when the strain-parameter relationship varies due to sensor shifts caused by long-term wearing or donning/doffing of braces. This letter presents a shift-adaptive estimation of knee joint angle. First, a brace is instrumented with two stretch sensors placed at different heights. Next, the different strain-angle relationships at varying brace shift positions are learned using Gaussian mixture models (GMMs). The system then estimates the joint angle from the sensor strains through Gaussian mixture regression using a maximum likelihood shift GMM, which is identified by referring to the two strains in a previous 1 s period. Experimental results indicated that the proposed method estimates the joint angle at multiple shift positions (0-20 mm) with higher accuracy than methods using a single model, single sensor, or referring to the present sensor strains.

Original languageEnglish
Article number9144406
Pages (from-to)5881-5888
Number of pages8
JournalIEEE Robotics and Automation Letters
Issue number4
Publication statusPublished - 2020 Oct


  • Automation in life sciences: Biotechnology
  • Gaussian mixture regression
  • human motion sensing
  • medical robots and systems
  • pharmaceutical and health care
  • wearable sensor

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Biomedical Engineering
  • Human-Computer Interaction
  • Mechanical Engineering
  • Computer Vision and Pattern Recognition
  • Computer Science Applications
  • Control and Optimization
  • Artificial Intelligence


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