Centre of pressure estimation during walking using only inertial-measurement units and end-to-end statistical modelling

Podobnik, Janez (author), Kraljić, David (author), Zadravec, Matjaž (author), Munih, Marko (author)

Estimation of the centre of pressure (COP) is an important part of the gait analysis, for example, when evaluating the functional capacity of individuals affected by motor impairment. Inertial measurement units (IMUs) and force sensors are commonly used to measure gait characteristic of healthy and impaired subjects. We present a methodology for estimating the COP solely from raw gyroscope, accelerometer, and magnetometer data from IMUs using statistical modelling. We demonstrate the viability of the method using an example of two models: a linear model and a non-linear Long-Short-Term Memory (LSTM) neural network model. Models were trained on the COP ground truth data measured using an instrumented treadmill and achieved the average intra-subject root mean square (RMS) error between estimated and ground truth COP of 12.3 mm and the average inter-subject RMS error of 23.7 mm which is comparable or better than similar studies so far. We show that the calibration procedure in the instrumented treadmill can be as short as a couple of minutes without the decrease in our model performance. We also show that the magnetic component of the recorded IMU signal, which is most sensitive to environmental changes, can be safely dropped without a significant decrease in model performance. Finally, we show that the number of IMUs can be reduced to five without deterioration in the model performance.

• Language: English
• Keywords: gait analysis, inertial measurement units, gait model, estimation of centre of pressure, artificial neural networks, wearable sensors, balance, rehabilitation
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FE - Faculty of Electrical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2020
• Number of pages: 20 str.
• Numbering: Vol. 20, iss. 21, art. 6136
• PID: 20.500.12556/RUL-134712
• UDC: 681.586
• ISSN on article: 1424-8220
• DOI: 10.3390/s20216136
• COBISS.SI-ID: 34924291
• Publication date in RUL: 27.01.2022

Record is a part of a journal

• Title: Sensors
• Shortened title: Sensors
• Publisher: MDPI
• ISSN: 1424-8220
• COBISS.SI-ID: 10176278

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 01.11.2020

Secondary language

• Language: Slovenian
• Keywords: analiza hoje, inercialna merilna enota, modeli hoje, ocena prijemališča sile, nevronske mreže, nosljivi senzorji