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Wearable Pedobarography System for Monitoring of Walk Related Parameters
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. (Embedded Sensor Systems for Health (ESS-H))ORCID iD: 0000-0003-2686-4539
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Health care costs have increased over the last decades due to an ageing population. Therefore, research in personal health monitoring (PHM) has increased in response to this. PHM has advantages such as mobility (monitoring of health at work or at home), early detection of health problems enabling preventive health measures and a reduction of health care cost. Human motion analysis, using for example pedobarography (PBG), is an important subcategory of PHM. PBG is used to study the force fields acting between the plantar surface of the foot and a supporting surface. Gait and posture analysis, prosthetics evaluation and monitoring of recovery from injury or disease are examples of PBG applications. Portable PBG can be performed using force sensing resistors built into the insole inside the shoe.

 In accordance with this, the research aim for this thesis is to design, build and evaluate a wireless wearable measurement system based on PBG for monitoring of walk related parameters. Monitoring of carried weight and walking speed were chosen as the applications for validation of the system. Motivations for choosing these applications are that there is a lack of a wearable system for monitoring of weight while walking and a possible combination with accelerometers to improve the estimation of walking speed. Both walking speed and weight are important factors for estimating energy expenditure. A portable system, that estimates weight while walking, enables monitoring of heavy working conditions.

The main research contributions include design of a PBG measurement system with a sensor implementation resulting in good sensor durability, several novel methods for weight estimation during walk and a novel method for analysing walking intensity and relating it to walking speed. The research results show that the new PBG system, in combination with the novel analysing methods, are suitable for use in wearable systems for monitoring of health related walk parameters.

Abstract [sv]

Kostnaderna för sjukvård har ökat de senaste decennierna på grund av att vi lever allt längre. Därför så har forskningen inom personlig hälsomonitorering (PHM) ökat som ett svar på detta. PHM har fördelar såsom mobilitet (monitorering av hälsa på jobbet eller i hemmet), tidig upptäckt av hälsoproblem gör det möjligt att sätta in förebyggande åtgärder för hälsa och reducera kostnaden för sjukvård. Rörelseanalys på människor, med hjälp av till exempel pedobarografi (PBG), är en viktig underkategori av PHM. PBG används för att studera kraftfält som verkar mellan fotens undersida och en uppbärande yta. Analys av gångstil och kroppshållning, utvärdering av proteser och övervakning av återhämtning från skada eller sjukdom är exempel på tillämpningar för PBG.

 I överrensstämmelse med detta är syftet för forskningen i den här avhandlingen att utforma, bygga och utvärdera ett trådlöst och bärbart mätsystem som bygger på PBG för övervakning av gångrelaterade parametrar. Övervakning av buren vikt och gånghastighet valdes som tillämpningarna för att utvärdera systemet. Motiveringar för att välja dessa tillämpningar är att det finns en brist på bärbara system för övervakning av vikt under gång och att en möjlig kombination med accelerometrar kan förbättra uppskattningen av gånghastighet. Både gånghastighet och vikt är viktiga faktorer vid uppskattning av energiförbrukning. Ett portabelt system, som uppskattar vikt under gång, möjliggör övervakning av tunga arbetsförhållanden.

 De främsta forskningsbidragen inkluderar utformningen av ett mätsystem baserat på PBG med sensorimplementering som ger lång livslängd för sensorerna, flera nya analysmetoder för uppskattning av vikt under gång och en ny analysmetod för gångintensitet som relateras till gånghastighet. Forskningsresultaten visar på att det nya PBG-systemet, i kombination med de nya analysmetoderna, är passande för användning i bärbara system för övervakning av hälsorelaterade gångparametrar.

Place, publisher, year, edition, pages
Västerås: Mälardalen University , 2019.
Series
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 301
National Category
Medical Engineering
Research subject
Electronics
Identifiers
URN: urn:nbn:se:mdh:diva-45546ISBN: 978-91-7485-444-2 (print)OAI: oai:DiVA.org:mdh-45546DiVA, id: diva2:1360980
Public defence
2019-12-06, Delta, Mälardalens högskola, Västerås, 13:30 (English)
Opponent
Supervisors
Funder
Knowledge Foundation, 20120275Available from: 2019-10-15 Created: 2019-10-14 Last updated: 2019-11-01Bibliographically approved
List of papers
1. Intelligent Wireless Body Area Network System for Human Motion Analysis
Open this publication in new window or tab >>Intelligent Wireless Body Area Network System for Human Motion Analysis
Show others...
2015 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Human motion analysis provides several important applications. Examples are fall risk assessment, sports biomechanics, physical activity monitoring and rehabilitation. This work in progress paper proposes an intelligent wireless body area network system for motion and gait symmetry analysis. A Bluetooth network with accelerometers, gyroscopes and in-shoe force sensing resistors gathers data and sends it to a web server after intelligent pre-processing and filtering. The system is flexible and adaptable for different use cases including combinations of gait analysis, gait symmetry and pressure measurements between foot and shoe.

Keywords
motion analysis, wireless, body area network, Bluetooth Low Energy
National Category
Medical Engineering
Identifiers
urn:nbn:se:mdh:diva-29459 (URN)978-1-61208-446-6 (ISBN)
Conference
SPWID 2015, The First International Conference on SmartPortable, Wearable, Implantable and Disability-oriented Devices andSystems
Funder
Knowledge Foundation
Available from: 2015-11-11 Created: 2015-11-11 Last updated: 2019-10-14Bibliographically approved
2. Wearable Weight Estimation System
Open this publication in new window or tab >>Wearable Weight Estimation System
2015 (English)In: Procedia Computer Science, vol. 64, 2015, Vol. 64, p. 146-152Conference paper, Published paper (Refereed)
Abstract [en]

Heavy working conditions, as well as sedentary behaviour, are risk factors for health. There is a lack of wearable measurement systems for monitoring carried loads while walking. Pedobarography, the study of force fields acting between the plantar surface of the foot and a supporting surface, is supposed to be useable for estimating carried loads. Purpose. The aim of this paper is to present a novel method for selecting appropriate measurement samples for weight estimation of carried load during walk and a wearable system, based on pedobarography, consisting of commercial off the shelf components. The main idea is to choose samples when half of the total weight is on the forward sensors and the other half is on the heel sensor “equipoise” in one foot while the other foot not touches the ground. Methods. The system consists of insoles with force sensing resistors, data acquisition with IOIO-OTG and analysis in Excel. Each subject was weighed on an electronic floor scale. Three walks were performed on level ground. The first walk without any added load and then with two increases of carried load. Equipoise was defined as having half the weight distributed on the heel and the other half over the metatarsal pad. An equipoise value of 0.5 represents equilibrium regarding the weight distribution on one foot, with the other foot in the air. Samples were chosen in the equipoise region of 0.5±0.1 and then the average of the samples collected during one minute estimated the total weight. Results. The system can detect increases in carried loads but has a tendency to overestimate them. The estimated value was always larger with increased weight but the system was not always linear. The average overestimation error was 16.7 kg. Discussion. This study shows that this type of wearable system is usable for estimating carried load during walk after calibration of the system to the body weight force distribution on the sensors. There is still need for future development to obtain real-time analysis and direct feedback. A smaller and lighter measurement system is also desirable. Conclusion. This study shows that the novel method, equipoise, is usable for selecting appropriate measurement samples for weight estimation of carried load during walk. This study also shows that the wearable system, consisting of commercial off the shelf components, can be used for these measurements. However, there is a tendency to overestimate the loads.

Series
Procedia Computer Science, ISSN 1877-0509 ; 64
Keywords
pedobarography, weight estimation, wearable, insole, in-shoe
National Category
Medical Engineering
Identifiers
urn:nbn:se:mdh:diva-29458 (URN)10.1016/j.procs.2015.08.475 (DOI)000373839900020 ()2-s2.0-84962909978 (Scopus ID)
Conference
Conference on ENTERprise Information Systems/International Conference on Project MANagement/Conference on Health and Social Care Information Systems and Technologies, CENTERIS/ProjMAN / HCist 2015 October 7-9, 2015
Funder
Knowledge Foundation
Available from: 2015-11-11 Created: 2015-11-11 Last updated: 2019-10-14Bibliographically approved
3. Walking Intensity Estimation with a Portable Pedobarography System
Open this publication in new window or tab >>Walking Intensity Estimation with a Portable Pedobarography System
2016 (English)In: Studies in Health Technology and Informatics, IOS Press , 2016, Vol. 224, p. 27-32Conference paper, Published paper (Refereed)
Abstract [en]

The aim of this pilot study was to investigate the possibility to find a correlation between the output from a portable pedobarography system and the walking intensity expressed as walking speed. The system uses shoe insoles with force sensing resistors and wireless transmission of the data via Bluetooth. The force-time integral, at the toe-off phase of the step, for the force sensors in the forward part of the right foot was used to measure impulse data for 10 subjects performing walks in three different walking speeds. This data was then corrected by multiplication with the step frequency. This pilot study indicates that the portable pedobarography system output shows a linear relationship with the walking intensity expressed as walking speed on an individual level.

Place, publisher, year, edition, pages
IOS Press, 2016
National Category
Medical Laboratory and Measurements Technologies
Research subject
Electronics
Identifiers
urn:nbn:se:mdh:diva-31533 (URN)10.3233/978-1-61499-653-8-27 (DOI)000385238500005 ()27225549 (PubMedID)2-s2.0-84973454832 (Scopus ID)
Conference
13th International Conference on Wearable, Micro & Nano Technologies for Personalized Health (pHealth 2016)
Projects
ESS-H
Funder
Knowledge Foundation, 20120275
Available from: 2016-05-24 Created: 2016-05-06 Last updated: 2019-10-14Bibliographically approved
4. Evaluation of the IngVaL Pedobarography System for Monitoring of Walking Speed
Open this publication in new window or tab >>Evaluation of the IngVaL Pedobarography System for Monitoring of Walking Speed
2018 (English)In: Healthcare Informatics Research, ISSN 2093-3681, E-ISSN 2093-369X, ISSN 2093-3681, Vol. 24, no 2, p. 118-124Article in journal (Refereed) Published
Abstract [en]

Objectives

Walking speed is an important component of movement and is a predictor of health in the elderly. Pedobarography, the study of forces acting between the plantar surface of the foot and a supporting surface, is an approach to estimating walking speed even when no global positioning system signal is available. The developed portable system, Identifying Velocity and Load (IngVaL), is a cost effective alternative to commercially available pedobarography systems because it only uses three force sensing resistors. In this study, the IngVaL system was evaluated. The three variables investigated in this study were the sensor durability, the proportion of analyzable steps, and the linearity between the system output and the walking speed.

Methods

Data was collected from 40 participants, each of whom performed five walks at five different self-paced walking speeds. The linearity between the walking speed and step frequency measured with R2 values was compared for the walking speed obtained ‘A’ only using amplitude data from the force sensors, ‘B’ that obtained only using the step frequency, and ‘C’ that obtained by combining amplitude data for each of the 40 test participants.

Results

Improvement of the wireless data transmission increased the percentage of analyzable steps from 83.1% measured with a prototype to 96.6% for IngVaL. The linearity comparison showed that the methods A, B, and C were accurate for 2, 15, and 23 participants, respectively.

Conclusions

Increased sensor durability and a higher percentage of analyzed steps indicates that IngVaL is an improvement over the prototype system. The combined strategy of amplitude and step frequency was confirmed as the most accurate method.

Place, publisher, year, edition, pages
Seoul: Korean Society of Medical Informatics (KOSMI), 2018
Keywords
Humans; Movement; Foot; Walking; Walking Speed
National Category
Medical Engineering
Research subject
Electronics
Identifiers
urn:nbn:se:mdh:diva-39225 (URN)10.4258/hir.2018.24.2.118 (DOI)000432090900004 ()29770245 (PubMedID)2-s2.0-85047476017 (Scopus ID)
Projects
Embedded Sensor Systems (ESS-H)
Funder
Knowledge Foundation, 20120275
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2019-10-14Bibliographically approved
5. Carried Weight Affects Walking Speed Monitoring with the IngVaL System
Open this publication in new window or tab >>Carried Weight Affects Walking Speed Monitoring with the IngVaL System
2019 (English)In: The Sixteenth International Conference on Wearable Micro and Nano Technologies for Personalized Health, pHealth 2019, June 10-12, Studies in health technology and informatics, volume 261, pages 317-320, 2019 / [ed] Bernd Blobel, Mauro Giacomini, Nieuwe Hemweg 6B 1013 BG Amsterdam, The Netherlands: NLM (Medline) , 2019, Vol. 261, p. 317-320Conference paper, Published paper (Refereed)
Abstract [en]

Earlier work has shown that the IngVaL pedobarography system can estimate walking speed during indoor walking using only three forefoot sensors. The aim of this study was to examine if monitoring of walking speed using data from these three forefoot sensors is affected of the weight a person carries, if the person performs a walk in a set speed on the treadmill. Shoe insoles with force sensing resistors were connected to an electronic unit for signal conditioning and sampling and then the data was sent via Bluetooth to a tablet. Fifteen test persons walked five times each carrying five different weights on the treadmill at 1 m/s. The force-time integrals for the sum of the three forefoot sensors were calculated. This study shows that the force-time integrals for the three forefoot sensors shows a linear relationship with the carried weight as long as the person is not fatigued.

Place, publisher, year, edition, pages
Nieuwe Hemweg 6B 1013 BG Amsterdam, The Netherlands: NLM (Medline), 2019
Series
Studies in Health Technology and Informatics, ISSN 0926-9630, E-ISSN 1879-8365 ; 261
Keywords
carried weight, in-shoe, insole, pedobarography, portable, wearable
National Category
Medical Engineering
Research subject
Electronics
Identifiers
urn:nbn:se:mdh:diva-44661 (URN)10.3233/978-1-61499-975-1-317 (DOI)2-s2.0-85067090455 (Scopus ID)978-1-61499-974-4 (ISBN)978-1-61499-975-1 (ISBN)
Conference
The Sixteenth International Conference on Wearable Micro and Nano Technologies for Personalized Health, pHealth 2019, June 10-12, Studies in health technology and informatics, volume 261, pages 317-320, 2019
Funder
Knowledge Foundation, 20120275
Available from: 2019-06-27 Created: 2019-06-27 Last updated: 2019-10-14
6. Monitoring of Carried Weight During Walk Using a Wearable Pedobarography System
Open this publication in new window or tab >>Monitoring of Carried Weight During Walk Using a Wearable Pedobarography System
2019 (English)In: The Fifth International Conference on Smart Portable, Wearable, Implantable and Disability-oriented Devices and Systems, SPWID 2019, July 28-August 2, pages 5-8, 2019 / [ed] Jaime Lloret, Universitat Politecnica de Valencia, Spain, IARIA, PO Box 7827, Wilmington, DE 19803, USA: International Academy, Research and Industry Association (IARIA), 2019, p. 5-8Conference paper, Published paper (Refereed)
Abstract [en]

Personal health monitoring is advantageous in heavy work environments to reduce the risk of wear and tear and acute injuries. The study of forces between the plantar surface of the foot and a supporting structure, pedobarography, is a  promising candidate for monitoring carried weight during walk. The aim of this study was to evaluate the cost effective pedobarography measurement system, IngVaL. Two aspects are evaluated, namely, how well IngVaL can monitor carried weight during walk and if the novel implementation increased the durability. Fifteen test persons made five treadmill walks with a carried weight of 10, 20, 0, 15, and 5 kg. The equipoise analysis method was used. The Root Mean Square Error (RMSE) for estimation of the carried weight was 13.8 kg. A study with the earlier version of the measurement system had a RMSE of 23.3 kg. The earlier system, as well as commercial systems using this kind of sensors, have problems with sensor durability. The new sensor implementation, where the active sensor area boundary was no longer affected by mechanical stress, resulted in no broken sensors. This study shows an increased performance of carried weight estimation compared with earlier work, together with an improved sensor durability.

Place, publisher, year, edition, pages
IARIA, PO Box 7827, Wilmington, DE 19803, USA: International Academy, Research and Industry Association (IARIA), 2019
Series
SPWID, International Conference on Smart Portable, Wearable, Implantable and Disability-oriented Devices and Systems, ISSN 2519-8440 ; 5
Keywords
pedobarography; carried weight; portable; wearable; insole; in-shoe
National Category
Medical Engineering
Research subject
Electronics
Identifiers
urn:nbn:se:mdh:diva-45370 (URN)978-1-61208-734-4 (ISBN)
Conference
The Fifth International Conference on Smart Portable, Wearable, Implantable and Disability-oriented Devices and Systems, SPWID 2019, July 28-August 2, pages 5-8, 2019
Funder
Knowledge Foundation, 20120275
Available from: 2019-10-03 Created: 2019-10-03 Last updated: 2019-10-14Bibliographically approved

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