John Nelson | University of Limerick (original) (raw)

Papers from 2007 (Gearóid ÓLaighin) by John Nelson

Research paper thumbnail of CAALYX: a new generation of location-based services in healthcare

Recent advances in mobile positioning systems and telecommunications are providing the technology... more Recent advances in mobile positioning systems and telecommunications are providing the technology needed for the development of location-aware tele-care applications. This paper introduces CAALYX -Complete Ambient Assisted Living Experiment, an EU-funded project that aims at increasing older people's autonomy and self-confidence by developing a wearable light device capable of measuring specific vital signs of the elderly, detecting falls and location, and communicating automatically in real-time with his/her care provider in case of an emergency, wherever the older person happens to be, at home or outside.

Papers by John Nelson

Research paper thumbnail of Cross-Layer Adaptive Design for the Frame Length of IEEE 802.11 Networks

Proceedings of the 6th Intl Symposium on Modeling and Optimization, 2008

In this paper, we study the cross-layer (between MAC and PHY) design problem for IEEE 802.11 wire... more In this paper, we study the cross-layer (between MAC and PHY) design problem for IEEE 802.11 wireless networks. It is focused on the design of the optimal length of the frame body. The following results are obtained: 1) The optimal length of the frame body in logarithmic scale, expressed as log L f,opt , can be coarsely approximated by a linear function of the signal-to-noise power ratio (SNR) E b /N0 (in dB) and finely approximated by a second-order polynomial of E b /N0; 2) The coefficients of the aforementioned approximation functions depend only on the data transmission rate and other parameters specified in the protocol, and they do not depend on the access mechanisms; 3) The number of active nodes has little effect on L f,opt , especially in the range of both low and high SNR; 4) The system throughput is sensitive to the length of the frame body L f when the SNR is low, while it is insensitive to L f in a considerably large neighborhood of L f,opt when the SNR is high; and 5) Fragmentation can always increase the system throughput, but the increasing rate is conspicuous only in the low SNR regime.

Research paper thumbnail of A system for activity recognition using multi-sensor fusion

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011

This paper proposes a system for activity recognition using multi-sensor fusion. In this system, ... more This paper proposes a system for activity recognition using multi-sensor fusion. In this system, four sensors are attached to the waist, chest, thigh, and side of the body. In the study we present two solutions for factors that affect the activity recognition accuracy: the calibration drift and the sensor orientation changing. The datasets used to evaluate this system were collected from 8 subjects who were asked to perform 8 scripted normal activities of daily living (ADL), three times each. The Naïve Bayes classifier using multi-sensor fusion is adopted and achieves 70.88%-97.66% recognition accuracies for 1-4 sensors.

Research paper thumbnail of Virtual Lab for Wireless Sensor Networks

Advances in Electrical and Computer Engineering, 2008

This article details an experimental system developed to enhance the education and research in th... more This article details an experimental system developed to enhance the education and research in the area of wireless networks technologies. The system referred, as Virtual Lab (VL) is primarily targeting first time users or users with limited experience in programming and using wireless sensor networks. The VL enables a set of predefined sensor networks to be remotely accessible and controlled for constructive and time-efficient experimentation. In order to facilitate the user's wireless sensor applications, the VL is using three main components: a) a Virtual Lab Motes (VLM), representing the wireless sensor, b) a Virtual Lab Client (VLC), representing the user's tool to interact with the VLM and c) a Virtual Lab Server (VLS) representing the software link between the VLM and VLC. The concept has been proven using the moteiv produced Tmote Sky modules. Initial experimental use clearly demonstrates that the VL approach reduces dramatically the learning curve involved in programming and using the associated wireless sensor nodes. In addition the VL allows the user's focus to be directed towards the experiment and not towards the software programming challenges.

Research paper thumbnail of Fall-detection through vertical velocity thresholding using a tri-axial accelerometer characterized using an optical motion-capture system

2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Vols 1-8, 2008

Falls in the elderly population are a major problem for today&amp... more Falls in the elderly population are a major problem for today's society. The immediate automatic detection of such events would help reduce the associated consequences of falls. This paper describes the development of an accurate, accelerometer-based fall detection system to distinguish between Activities of Daily Living (ADL) and falls. It has previously been shown that falls can be distinguished from normal ADL through vertical velocity thresholding using an optical motion capture system. In this study however accurate vertical velocity profiles of the trunk were generated by simple signal processing of the signals from a tri-axial accelerometer (TA). By recording simulated falls onto crash mats and ADL performed by 5 young healthy subjects, using both a single chest mounted TA and using an optical motion capture system, the accuracy of the vertical velocity profiles was assessed. Data analysis was performed using MATLAB to determine the peak velocities recorded and RMS error during four different fall and six ADL types. Results show high correlations and low percentage errors between the vertical velocity profiles generated by the TA to those recorded using the optical motion capture system. In addition, through thresholding of the vertical velocity profiles generated using the TA at -1.3m/s, falls can be distinguished from normal ADL with 100% sensitivity and specificity.

Research paper thumbnail of Real-time low-energy fall detection algorithm with a programmable truncated MAC

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference, 2010

The ability to discriminate between falls and activities of daily living (ADL) has been investiga... more The ability to discriminate between falls and activities of daily living (ADL) has been investigated by using tri-axial accelerometer sensors, mounted on the trunk and using simulated falls performed by young healthy subjects under supervised conditions and ADL performed by elderly subjects. In this paper we propose a power-aware real-time fall detection integrated circuit (IC) that can distinguish Falls from ADL by processing the accelerations measured during 240 falls and 240 ADL. In the proposed fixed point custom DSP architecture, a threshold algorithm was implemented to analyze the effectiveness of Programmable Truncated Multiplication regarding power reduction while maintaining a high output accuracy. The presented system runs a real time implementation of the algorithm on a low power architecture that allows up to 23% power savings through its digital blocks when compared to a standard implementation, without any accuracy loss.

Research paper thumbnail of Optimum gravity vector and vertical acceleration estimation using a tri-axial accelerometer for falls and normal activities

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference, 2011

Research paper thumbnail of An integrated fall and mobility sensor and wireless health signs monitoring system

2008 IEEE Sensors, 2008

... Department of Electronic & Computer Engineering University of Limerick, Ireland Email:pep... more ... Department of Electronic & Computer Engineering University of Limerick, Ireland Email:pepijn.vandeven@ul.ie ... It is estimated that yearly one in three elderly people 65 years or older in the UK experience a serious fall [3]. The results of a fall can be dramatic, leading to long ...

Research paper thumbnail of Design and test of a long-term fall detection system incorporated into a custom vest for the elderly

IET Irish Signals and Systems Conference (ISSC 2008), 2008

... Department of Electronic and Computer Engineering, University of Limerick, Limerick. email: a... more ... Department of Electronic and Computer Engineering, University of Limerick, Limerick. email: alan.bourke@ul.ie email: pepijn.vandeven@ul.ie email: john.nelson@ul.ie ... On average, one in every three adults, 65 years old or older, falls each year [1]. 307 Page 2. ...

Research paper thumbnail of Unobtrusive monitoring and identification of fall accidents

Medical Engineering & Physics, 2015

Falls are a societal and economic problem of great concern with large parts of the population, in... more Falls are a societal and economic problem of great concern with large parts of the population, in particular older citizens, at significant risk and the result of a fall often being grave. It has long been established that it is of importance to provide help to a faller soon after the event to prevent complications and this can be achieved with a fall monitor. Yet, the practical use of currently available fall monitoring solutions is limited due to accuracy, usability, cost, and, not in the least, the stigmatising effect of many solutions. This paper proposes a fall sensor concept that can be embedded in the user's footwear and discusses algorithms, software and hardware developed. Sensor performance is illustrated using results of a series of functional tests. These show that the developed sensor can be used for the accurate measurement of various mobility and gait parameters and that falls are detected accurately.

Research paper thumbnail of Energy expenditure estimation using accelerometry and heart rate for multiple sclerosis and healthy older adults

Research paper thumbnail of Embedded fall and activity monitoring for a wearable ambient assisted living solution for older adults

With the rapidly increasing over 60 and over 80 age groups in society, greater emphasis will be p... more With the rapidly increasing over 60 and over 80 age groups in society, greater emphasis will be put on technology to detect emergency situations, such as falls, in order to promote independent living. This paper describes the development and deployment of fall-detection, activity classification and energy expenditure algorithms, deployed in a tele-monitoring system. These algorithms were successfully tested in an end-user trial involving 9 elderly volunteers using the system for 28 days.

Research paper thumbnail of Activity level classification algorithm using SHIMMER™ wearable sensors for individuals with rheumatoid arthritis

In rheumatoid arthritis (RA) it is believed that symptoms associated with the progression of the ... more In rheumatoid arthritis (RA) it is believed that symptoms associated with the progression of the disease result in a reduction in the physical activity level of the patient. One of the key flaws of the research surrounding this hypothesis to date is the use of non-validated physical activity outcomes measures. In this study, an algorithm to estimate physical activity levels in patients as they perform a simulated protocol of typical activities of daily living using SHIMMER kinematic sensors, incorporating tri-axial gyroscopes and accelerometers, is proposed. The results are validated against simultaneously recorded energy expenditure data and the defined activity protocol and demonstrate that SHIMMER can be used to accurately estimate physical activity levels in RA populations.

Research paper thumbnail of Fall algorithm development using kinematic parameters measured from simulated falls performed in a quasi-realistic environment using accelerometry

This study aims to determine the optimal temporal, angular and acceleration parameters and thresh... more This study aims to determine the optimal temporal, angular and acceleration parameters and thresholds for an accelerometer based, chest-worn, fall detection algorithm. In total, 10 healthy male subjects performed 14 different fall types, 3 times by each. The falls were performed onto in a quasi-realistic environment consisting of mats of a minimum thickness. Optimum parameters for; t(falling): time-to-fall, θ(max): max-angle, t(θmax) : max-angle-time, t(RTStanding) : Return-to-standing-time and t(lying) : lying-time were determined using a data set consisting of a total of 420 falls.

Research paper thumbnail of Assessment of waist-worn tri-axial accelerometer based fall-detection algorithms using continuous unsupervised activities

This study aims to evaluate a variety of existing and novel fall detection algorithms, for a wais... more This study aims to evaluate a variety of existing and novel fall detection algorithms, for a waist mounted accelerometer based system. Algorithms were tested against a comprehensive data-set recorded from 10 young healthy subjects performing 240 falls and 120 activities of daily living and 10 elderly healthy subjects performing 240 scripted and 52.4 hours of continuous unscripted normal activities.

Research paper thumbnail of Evaluation of waist-mounted tri-axial accelerometer based fall-detection algorithms during scripted and continuous unscripted activities

It is estimated that by 2050 more than one in five people will be aged 65 or over. In this age gr... more It is estimated that by 2050 more than one in five people will be aged 65 or over. In this age group, falls are one of the most serious life-threatening events that can occur. Their automatic detection would help reduce the time of arrival of medical attention, thus reducing the mortality rate and in turn promoting independent living. This study evaluated a variety of existing and novel fall-detection algorithms for a waist-mounted accelerometer based system. In total, 21 algorithms of varying degrees of complexity were tested against a comprehensive data-set recorded from 10 young healthy volunteers performing 240 falls and 120 activities of daily living (ADL) and 10 elderly healthy volunteers performing 240 scripted ADL and 52.4 waking hours of continuous unscripted normal ADL. Results show that using an algorithm that employs thresholds in velocity, impact and posture (velocity+impact+posture) achieves 100% specificity and sensitivity with a false-positive rate of less than 1 false-positive (0.6 false-positives) per day of waking hours. This algorithm is the most suitable method of fall-detection, when tested using continuous unscripted activities performed by elderly healthy volunteers, which is the target environment for a fall-detection device.

Research paper thumbnail of The measurement of sedentary patterns and behaviors using the activPAL™ Professional physical activity monitor

Physiological Measurement, 2012

Epidemiological studies have associated the negative effects of sedentary time and sedentary patt... more Epidemiological studies have associated the negative effects of sedentary time and sedentary patterns on health indices. However, these studies have used methodologies that do not directly measure the sedentary state. Recent technological developments in the area of motion sensors have incorporated inclinometers, which can measure the inclination of the body directly, without relying on self-report or count thresholds. This paper aims to provide a detailed description of methodologies used to examine a range of relevant variables, including sedentary levels and patterns from an inclinometer-based motion sensor. The activPAL Professional physical activity logger provides an output which can be interpreted and used without the need for further processing and additional variables were derived using a custom designed MATLAB R computer program. The methodologies described have been implemented on a sample of 44 adolescent females, and the results of a range of daily physical activity and sedentary variables are described and presented. The results provide a range of objectively measured and objectively processed variables, including total time spent sitting/lying, standing and stepping, number and duration of daily sedentary bouts and both bed hours and non-bed hours, which may be of interest when making association between physical activity, sedentary behaviors and health indices.

Research paper thumbnail of Design and Integration of Fall and Mobility Monitors in Health Monitoring Platforms

Wearable and Autonomous Biomedical Devices and Systems for Smart Environment: Issues and Characterization, Nov 4, 2010

This chapter discusses the design and integration of fall and mobility sensor platforms for mobil... more This chapter discusses the design and integration of fall and mobility sensor platforms for mobile and remote health signs monitoring. With a steadily increasing elderly population in Europe [1] and indeed throughout significant parts of the rest of the world, health services for elderly people are placing a growing strain on national health budgets [2] and the availability of nursing and care taker staff. Additionally, perhaps due to the advent of technology in general and changing social relations in society, there is an ever-increasing ...

Research paper thumbnail of Smart phone interfaces to wireless health sensors

e-Health Networking …, Jul 1, 2010

This paper discusses user and system interfaces for mobile health-monitoring systems. Current app... more This paper discusses user and system interfaces for mobile health-monitoring systems. Current approaches often use entirely web based solutions, however with mobile phones being extremely widespread and becoming ever more powerful, there is a strong case to be made for their use as interfaces to wearable health sensors. Phones provide a socially appropriate means of displaying timely information to the user and enable the sensors to transmit measurements directly to health care providers. In this paper we ...

Research paper thumbnail of Real-time low-energy fall detection algorithm with a Programmable Truncated MAC

The ability to discriminate between falls and activities of daily living (ADL) has been investiga... more The ability to discriminate between falls and activities of daily living (ADL) has been investigated by using tri-axial accelerometer sensors, mounted on the trunk and using simulated falls performed by young healthy subjects under supervised conditions and ADL performed by elderly subjects. In this paper we propose a power-aware real-time fall detection integrated circuit (IC) that can distinguish Falls from ADL by processing the accelerations measured during 240 falls and 240 ADL. In the proposed fixed point custom DSP architecture, a threshold algorithm was implemented to analyze the effectiveness of Programmable Truncated Multiplication regarding power reduction while maintaining a high output accuracy. The presented system runs a real time implementation of the algorithm on a low power architecture that allows up to 23% power savings through its digital blocks when compared to a standard implementation, without any accuracy loss.

Research paper thumbnail of CAALYX: a new generation of location-based services in healthcare

Recent advances in mobile positioning systems and telecommunications are providing the technology... more Recent advances in mobile positioning systems and telecommunications are providing the technology needed for the development of location-aware tele-care applications. This paper introduces CAALYX -Complete Ambient Assisted Living Experiment, an EU-funded project that aims at increasing older people's autonomy and self-confidence by developing a wearable light device capable of measuring specific vital signs of the elderly, detecting falls and location, and communicating automatically in real-time with his/her care provider in case of an emergency, wherever the older person happens to be, at home or outside.

Research paper thumbnail of Cross-Layer Adaptive Design for the Frame Length of IEEE 802.11 Networks

Proceedings of the 6th Intl Symposium on Modeling and Optimization, 2008

In this paper, we study the cross-layer (between MAC and PHY) design problem for IEEE 802.11 wire... more In this paper, we study the cross-layer (between MAC and PHY) design problem for IEEE 802.11 wireless networks. It is focused on the design of the optimal length of the frame body. The following results are obtained: 1) The optimal length of the frame body in logarithmic scale, expressed as log L f,opt , can be coarsely approximated by a linear function of the signal-to-noise power ratio (SNR) E b /N0 (in dB) and finely approximated by a second-order polynomial of E b /N0; 2) The coefficients of the aforementioned approximation functions depend only on the data transmission rate and other parameters specified in the protocol, and they do not depend on the access mechanisms; 3) The number of active nodes has little effect on L f,opt , especially in the range of both low and high SNR; 4) The system throughput is sensitive to the length of the frame body L f when the SNR is low, while it is insensitive to L f in a considerably large neighborhood of L f,opt when the SNR is high; and 5) Fragmentation can always increase the system throughput, but the increasing rate is conspicuous only in the low SNR regime.

Research paper thumbnail of A system for activity recognition using multi-sensor fusion

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011

This paper proposes a system for activity recognition using multi-sensor fusion. In this system, ... more This paper proposes a system for activity recognition using multi-sensor fusion. In this system, four sensors are attached to the waist, chest, thigh, and side of the body. In the study we present two solutions for factors that affect the activity recognition accuracy: the calibration drift and the sensor orientation changing. The datasets used to evaluate this system were collected from 8 subjects who were asked to perform 8 scripted normal activities of daily living (ADL), three times each. The Naïve Bayes classifier using multi-sensor fusion is adopted and achieves 70.88%-97.66% recognition accuracies for 1-4 sensors.

Research paper thumbnail of Virtual Lab for Wireless Sensor Networks

Advances in Electrical and Computer Engineering, 2008

This article details an experimental system developed to enhance the education and research in th... more This article details an experimental system developed to enhance the education and research in the area of wireless networks technologies. The system referred, as Virtual Lab (VL) is primarily targeting first time users or users with limited experience in programming and using wireless sensor networks. The VL enables a set of predefined sensor networks to be remotely accessible and controlled for constructive and time-efficient experimentation. In order to facilitate the user's wireless sensor applications, the VL is using three main components: a) a Virtual Lab Motes (VLM), representing the wireless sensor, b) a Virtual Lab Client (VLC), representing the user's tool to interact with the VLM and c) a Virtual Lab Server (VLS) representing the software link between the VLM and VLC. The concept has been proven using the moteiv produced Tmote Sky modules. Initial experimental use clearly demonstrates that the VL approach reduces dramatically the learning curve involved in programming and using the associated wireless sensor nodes. In addition the VL allows the user's focus to be directed towards the experiment and not towards the software programming challenges.

Research paper thumbnail of Fall-detection through vertical velocity thresholding using a tri-axial accelerometer characterized using an optical motion-capture system

2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Vols 1-8, 2008

Falls in the elderly population are a major problem for today&amp... more Falls in the elderly population are a major problem for today's society. The immediate automatic detection of such events would help reduce the associated consequences of falls. This paper describes the development of an accurate, accelerometer-based fall detection system to distinguish between Activities of Daily Living (ADL) and falls. It has previously been shown that falls can be distinguished from normal ADL through vertical velocity thresholding using an optical motion capture system. In this study however accurate vertical velocity profiles of the trunk were generated by simple signal processing of the signals from a tri-axial accelerometer (TA). By recording simulated falls onto crash mats and ADL performed by 5 young healthy subjects, using both a single chest mounted TA and using an optical motion capture system, the accuracy of the vertical velocity profiles was assessed. Data analysis was performed using MATLAB to determine the peak velocities recorded and RMS error during four different fall and six ADL types. Results show high correlations and low percentage errors between the vertical velocity profiles generated by the TA to those recorded using the optical motion capture system. In addition, through thresholding of the vertical velocity profiles generated using the TA at -1.3m/s, falls can be distinguished from normal ADL with 100% sensitivity and specificity.

Research paper thumbnail of Real-time low-energy fall detection algorithm with a programmable truncated MAC

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference, 2010

The ability to discriminate between falls and activities of daily living (ADL) has been investiga... more The ability to discriminate between falls and activities of daily living (ADL) has been investigated by using tri-axial accelerometer sensors, mounted on the trunk and using simulated falls performed by young healthy subjects under supervised conditions and ADL performed by elderly subjects. In this paper we propose a power-aware real-time fall detection integrated circuit (IC) that can distinguish Falls from ADL by processing the accelerations measured during 240 falls and 240 ADL. In the proposed fixed point custom DSP architecture, a threshold algorithm was implemented to analyze the effectiveness of Programmable Truncated Multiplication regarding power reduction while maintaining a high output accuracy. The presented system runs a real time implementation of the algorithm on a low power architecture that allows up to 23% power savings through its digital blocks when compared to a standard implementation, without any accuracy loss.

Research paper thumbnail of Optimum gravity vector and vertical acceleration estimation using a tri-axial accelerometer for falls and normal activities

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference, 2011

Research paper thumbnail of An integrated fall and mobility sensor and wireless health signs monitoring system

2008 IEEE Sensors, 2008

... Department of Electronic & Computer Engineering University of Limerick, Ireland Email:pep... more ... Department of Electronic & Computer Engineering University of Limerick, Ireland Email:pepijn.vandeven@ul.ie ... It is estimated that yearly one in three elderly people 65 years or older in the UK experience a serious fall [3]. The results of a fall can be dramatic, leading to long ...

Research paper thumbnail of Design and test of a long-term fall detection system incorporated into a custom vest for the elderly

IET Irish Signals and Systems Conference (ISSC 2008), 2008

... Department of Electronic and Computer Engineering, University of Limerick, Limerick. email: a... more ... Department of Electronic and Computer Engineering, University of Limerick, Limerick. email: alan.bourke@ul.ie email: pepijn.vandeven@ul.ie email: john.nelson@ul.ie ... On average, one in every three adults, 65 years old or older, falls each year [1]. 307 Page 2. ...

Research paper thumbnail of Unobtrusive monitoring and identification of fall accidents

Medical Engineering & Physics, 2015

Falls are a societal and economic problem of great concern with large parts of the population, in... more Falls are a societal and economic problem of great concern with large parts of the population, in particular older citizens, at significant risk and the result of a fall often being grave. It has long been established that it is of importance to provide help to a faller soon after the event to prevent complications and this can be achieved with a fall monitor. Yet, the practical use of currently available fall monitoring solutions is limited due to accuracy, usability, cost, and, not in the least, the stigmatising effect of many solutions. This paper proposes a fall sensor concept that can be embedded in the user's footwear and discusses algorithms, software and hardware developed. Sensor performance is illustrated using results of a series of functional tests. These show that the developed sensor can be used for the accurate measurement of various mobility and gait parameters and that falls are detected accurately.

Research paper thumbnail of Energy expenditure estimation using accelerometry and heart rate for multiple sclerosis and healthy older adults

Research paper thumbnail of Embedded fall and activity monitoring for a wearable ambient assisted living solution for older adults

With the rapidly increasing over 60 and over 80 age groups in society, greater emphasis will be p... more With the rapidly increasing over 60 and over 80 age groups in society, greater emphasis will be put on technology to detect emergency situations, such as falls, in order to promote independent living. This paper describes the development and deployment of fall-detection, activity classification and energy expenditure algorithms, deployed in a tele-monitoring system. These algorithms were successfully tested in an end-user trial involving 9 elderly volunteers using the system for 28 days.

Research paper thumbnail of Activity level classification algorithm using SHIMMER™ wearable sensors for individuals with rheumatoid arthritis

In rheumatoid arthritis (RA) it is believed that symptoms associated with the progression of the ... more In rheumatoid arthritis (RA) it is believed that symptoms associated with the progression of the disease result in a reduction in the physical activity level of the patient. One of the key flaws of the research surrounding this hypothesis to date is the use of non-validated physical activity outcomes measures. In this study, an algorithm to estimate physical activity levels in patients as they perform a simulated protocol of typical activities of daily living using SHIMMER kinematic sensors, incorporating tri-axial gyroscopes and accelerometers, is proposed. The results are validated against simultaneously recorded energy expenditure data and the defined activity protocol and demonstrate that SHIMMER can be used to accurately estimate physical activity levels in RA populations.

Research paper thumbnail of Fall algorithm development using kinematic parameters measured from simulated falls performed in a quasi-realistic environment using accelerometry

This study aims to determine the optimal temporal, angular and acceleration parameters and thresh... more This study aims to determine the optimal temporal, angular and acceleration parameters and thresholds for an accelerometer based, chest-worn, fall detection algorithm. In total, 10 healthy male subjects performed 14 different fall types, 3 times by each. The falls were performed onto in a quasi-realistic environment consisting of mats of a minimum thickness. Optimum parameters for; t(falling): time-to-fall, θ(max): max-angle, t(θmax) : max-angle-time, t(RTStanding) : Return-to-standing-time and t(lying) : lying-time were determined using a data set consisting of a total of 420 falls.

Research paper thumbnail of Assessment of waist-worn tri-axial accelerometer based fall-detection algorithms using continuous unsupervised activities

This study aims to evaluate a variety of existing and novel fall detection algorithms, for a wais... more This study aims to evaluate a variety of existing and novel fall detection algorithms, for a waist mounted accelerometer based system. Algorithms were tested against a comprehensive data-set recorded from 10 young healthy subjects performing 240 falls and 120 activities of daily living and 10 elderly healthy subjects performing 240 scripted and 52.4 hours of continuous unscripted normal activities.

Research paper thumbnail of Evaluation of waist-mounted tri-axial accelerometer based fall-detection algorithms during scripted and continuous unscripted activities

It is estimated that by 2050 more than one in five people will be aged 65 or over. In this age gr... more It is estimated that by 2050 more than one in five people will be aged 65 or over. In this age group, falls are one of the most serious life-threatening events that can occur. Their automatic detection would help reduce the time of arrival of medical attention, thus reducing the mortality rate and in turn promoting independent living. This study evaluated a variety of existing and novel fall-detection algorithms for a waist-mounted accelerometer based system. In total, 21 algorithms of varying degrees of complexity were tested against a comprehensive data-set recorded from 10 young healthy volunteers performing 240 falls and 120 activities of daily living (ADL) and 10 elderly healthy volunteers performing 240 scripted ADL and 52.4 waking hours of continuous unscripted normal ADL. Results show that using an algorithm that employs thresholds in velocity, impact and posture (velocity+impact+posture) achieves 100% specificity and sensitivity with a false-positive rate of less than 1 false-positive (0.6 false-positives) per day of waking hours. This algorithm is the most suitable method of fall-detection, when tested using continuous unscripted activities performed by elderly healthy volunteers, which is the target environment for a fall-detection device.

Research paper thumbnail of The measurement of sedentary patterns and behaviors using the activPAL™ Professional physical activity monitor

Physiological Measurement, 2012

Epidemiological studies have associated the negative effects of sedentary time and sedentary patt... more Epidemiological studies have associated the negative effects of sedentary time and sedentary patterns on health indices. However, these studies have used methodologies that do not directly measure the sedentary state. Recent technological developments in the area of motion sensors have incorporated inclinometers, which can measure the inclination of the body directly, without relying on self-report or count thresholds. This paper aims to provide a detailed description of methodologies used to examine a range of relevant variables, including sedentary levels and patterns from an inclinometer-based motion sensor. The activPAL Professional physical activity logger provides an output which can be interpreted and used without the need for further processing and additional variables were derived using a custom designed MATLAB R computer program. The methodologies described have been implemented on a sample of 44 adolescent females, and the results of a range of daily physical activity and sedentary variables are described and presented. The results provide a range of objectively measured and objectively processed variables, including total time spent sitting/lying, standing and stepping, number and duration of daily sedentary bouts and both bed hours and non-bed hours, which may be of interest when making association between physical activity, sedentary behaviors and health indices.

Research paper thumbnail of Design and Integration of Fall and Mobility Monitors in Health Monitoring Platforms

Wearable and Autonomous Biomedical Devices and Systems for Smart Environment: Issues and Characterization, Nov 4, 2010

This chapter discusses the design and integration of fall and mobility sensor platforms for mobil... more This chapter discusses the design and integration of fall and mobility sensor platforms for mobile and remote health signs monitoring. With a steadily increasing elderly population in Europe [1] and indeed throughout significant parts of the rest of the world, health services for elderly people are placing a growing strain on national health budgets [2] and the availability of nursing and care taker staff. Additionally, perhaps due to the advent of technology in general and changing social relations in society, there is an ever-increasing ...

Research paper thumbnail of Smart phone interfaces to wireless health sensors

e-Health Networking …, Jul 1, 2010

This paper discusses user and system interfaces for mobile health-monitoring systems. Current app... more This paper discusses user and system interfaces for mobile health-monitoring systems. Current approaches often use entirely web based solutions, however with mobile phones being extremely widespread and becoming ever more powerful, there is a strong case to be made for their use as interfaces to wearable health sensors. Phones provide a socially appropriate means of displaying timely information to the user and enable the sensors to transmit measurements directly to health care providers. In this paper we ...

Research paper thumbnail of Real-time low-energy fall detection algorithm with a Programmable Truncated MAC

The ability to discriminate between falls and activities of daily living (ADL) has been investiga... more The ability to discriminate between falls and activities of daily living (ADL) has been investigated by using tri-axial accelerometer sensors, mounted on the trunk and using simulated falls performed by young healthy subjects under supervised conditions and ADL performed by elderly subjects. In this paper we propose a power-aware real-time fall detection integrated circuit (IC) that can distinguish Falls from ADL by processing the accelerations measured during 240 falls and 240 ADL. In the proposed fixed point custom DSP architecture, a threshold algorithm was implemented to analyze the effectiveness of Programmable Truncated Multiplication regarding power reduction while maintaining a high output accuracy. The presented system runs a real time implementation of the algorithm on a low power architecture that allows up to 23% power savings through its digital blocks when compared to a standard implementation, without any accuracy loss.

Research paper thumbnail of Unobtrusive monitoring and identification of fall accidents

Medical Engineering & Physics, 2015

Falls are a societal and economic problem of great concern with large parts of the population, in... more Falls are a societal and economic problem of great concern with large parts of the population, in particular older citizens, at significant risk and the result of a fall often being grave. It has long been established that it is of importance to provide help to a faller soon after the event to prevent complications and this can be achieved with a fall monitor. Yet, the practical use of currently available fall monitoring solutions is limited due to accuracy, usability, cost, and, not in the least, the stigmatising effect of many solutions. This paper proposes a fall sensor concept that can be embedded in the user's footwear and discusses algorithms, software and hardware developed. Sensor performance is illustrated using results of a series of functional tests. These show that the developed sensor can be used for the accurate measurement of various mobility and gait parameters and that falls are detected accurately.