An Activity Classifier based on Heart Rate and Accelerometer Data Fusion

The European project ProeTEX realized a novel set of prototypes based on smart garments that integrate sensors for the real-time monitoring of physiological, activity-related and environmental parameters of the emergency operators during their interventions. The availability of these parameters and the emergency scenario suggest the implementation of novel classification methods aimed at detecting dangerous status of the rescuer automatically, and based not only on the classical activityrelated signals, rather on a combination of these data with the physiological status of the subject. Here we propose a heart rate and accelerometer data fusion algorithm for the activity classification of rescuers in the emergency context

Using Type-2 Fuzzy Models to Detect Fall Incidents and Abnormal Gaits Among Elderly

— June 2012, 11% of the overall population in Taiwan was over the age of 65. This ratio is higher than the average figure for the United Nations (8%) . Critical issues concerning elderly in healthcare include fall detection, loneliness prevention and retard of obliviousness. In this study we design type-2 fuzzy models that utilize smart phone tri-axial accelerometer signals to detect fall incidents and identify abnormal gaits among elderly. Once a fall incident is detected an alarm is sent to notify the medical staff for taking any necessary treatment. When the proposed system is used as a pedometer, all the tri-axial accelerometer signals are used to identify the gaits during walking. Based on the proposed type-2 fuzzy models, the walking gaits can be identified as normal, left-tilted, and right-tilted. Experimental results from type-2 fuzzy models reveal that the accuracy rates in identifying normal walking and fall over are 92.3% and 100%, respectively, exceeding what are obtained using type-1 fuzzy models

PERHITUNGAN FAKTOR KALIBRASI SENSOR AKSELEROMETER MMA7361L PADA KETIGA SUMBU DENGAN MENGGUNAKAN SIMULATOR ST-3176-TC-10

Abstrak Akselerometer adalah sensor percepatan yang banyak dipakai sebagai komponen utama dalam pembuatan IMU (Inertial Measurement Unit). Akselerometer MMA7361L merupakan sensor percepatan dengan 2 pilihan tingkat sensitivitas, yaitu 800 mV/g dan 206 mV/g. Sensor akselerometer yang dijual belum terkalibrasi, sehingga sensor harus dikalibrasi sebelum digunakan. Kalibrasi akselerometer dipengaruhi oleh tegangan catu daya, sehingga diperlukan catu daya yang stabil dalam pemakaiannya. Faktor kalibrasi merupakan faktor pengali yang mengubah data ADC keluaran sensor menjadi nilai percepatan hasil pengukuran. Alat utama yang digunakan untuk melakukan kalibrasi sensor dan pengujian sensor adalah simulator gerak 3 sumbu ST-3176-TC-10. Hasil pengujian menunjukkan bahwa sensor dengan tipe yang sama mempunyai faktor kalibrasi yang berbeda-beda, sehingga setiap sensor harus dikalibrasi sebelum digunakan. Faktor kalibrasi suatu sensor tidak dapat digunakan untuk sensor yang lain meskipun tipenya sama

HuMOVE: a low-invasive wearable monitoring platform in sexual medicine

OBJECTIVE: To investigate an accelerometer-based wearable system, named Human Movement (HuMOVE) platform, designed to enable quantitative and continuous measurement of sexual performance with minimal invasiveness and inconvenience for users. MATERIALS AND METHODS: Design, implementation, and development of HuMOVE, a wearable platform equipped with an accelerometer sensor for monitoring inertial parameters for sexual performance assessment and diagnosis, were performed. The system enables quantitative measurement of movement parameters during sexual intercourse, meeting the requirements of wearability, data storage, sampling rate, and interfacing methods, which are fundamental for human sexual intercourse performance analysis. HuMOVE was validated through characterization using a controlled experimental test bench and evaluated in a human model during simulated sexual intercourse conditions. RESULTS: HuMOVE demonstrated to be a robust and quantitative monitoring platform and a reliable candidate for sexual performance evaluation and diagnosis. Characterization analysis on the controlled experimental test bench demonstrated an accurate correlation between the HuMOVE system and data from a reference displacement sensor. Experimental tests in the human model during simulated intercourse conditions confirmed the accuracy of the sexual performance evaluation platform and the effectiveness of the selected and derived parameters. The obtained outcomes also established the project expectations in terms of usability and comfort, evidenced by the questionnaires that highlighted the low invasiveness and acceptance of the device. CONCLUSION: To the best of our knowledge, HuMOVE platform is the first device for human sexual performance analysis compatible with sexual intercourse; the system has the potential to be a helpful tool for physicians to accurately classify sexual disorders, such as premature or delayed ejaculation

KALIBRASI SENSOR MULTIGAIN AKSELEROMETER DENGAN ACUAN PERCEPATAN GRAVITASI BUMI

Akselerometer merupakan salah satu sensor percepatan yang banyak dipakai dalam pembuatan IMU (Inertial Measurement Unit). Sensor akselerometer dijual di pasaran dalam keadaan belum terkalibrasi, sehingga tidak bias langsung digunakan. MMA7361L merupakan akselerometer dengan 2 pilihan tingkat sensitivitas, yaitu 1,5 g dan 6 g, sehingga penggabungan 2 unit sensor tersebut dapat digunakan dalam perancangan sensor multigain. Kalibrasi akselerometer dipengaruhi oleh tegangan catu daya, sehingga diperlukan catu daya yang stabil dalam pemakaiannya. Keluaran sensor pada saat tidak ada eksitasi dari luar disebut sebagai nilai offset sensor. Kalibrasi sensor multigrain dapat dilakukan secara bersamaan dengan membandingkan percepatan gravitasi bumi. Alat utama yang digunakan untuk melakukan kalibrasi sensor dan pengujian sensor adalah simulator gerak 3 sumbu ST-3176-TC-10. Hasil pengujian menunjukkan bahwa sensor dengan tipe yang sama mempunyai sensitivitas dan nilai offset yang berbedabeda. Sensor MMA7361L 1,5 g mempunyai nilai sensitivitas yang lebih tinggi dan nilai (Root Mean Square Error) RMSE yang lebih rendah jika dibandingkan dengan MMA7361L 6 g

KALIBRASI SENSOR MULTIGAIN AKSELEROMETER DENGAN ACUANPERCEPATAN GRAVITASI BUMI Cover

eprints.undip.ac.id/7182

Estimation of Energy Expenditure in Wheelchair-Bound Spinal Cord Injured Individuals Using Inertial Measurement Units

A healthy lifestyle reduces the risk of cardio-vascular disease. As wheelchair-bound individuals with spinal cord injury (SCI) are challenged in their activities, promoting and coaching an active lifestyle is especially relevant. Although there are many commercial activity trackers available for the able-bodied population, including those providing feedback about energy expenditure (EE), activity trackers for the SCI population are largely lacking, or are limited to a small set of activities performed in controlled settings. The aims of the present study were to develop and validate an algorithm based on inertial measurement unit (IMU) data to continuously monitor EE in wheelchair-bound individuals with a SCI, and to establish reference activity values for a healthy lifestyle in this population. For this purpose, EE was measured in 30 subjects each wearing four IMUs during 12 different physical activities, randomly selected from a list of 24 activities of daily living. The proposed algorithm consists of three parts: resting EE estimation based on multi-linear regression, an activity classification using a k-nearest-neighbors algorithm, and EE estimation based on artificial neural networks (ANNs). The mean absolute estimation error for the ANN-based algorithm was 14.4% compared to indirect calorimeter measurements. Based on reference values from the literature and the data collected within this study, we recommend wheeling 3 km per day for a healthy lifestyle in wheelchair-bound SCI individuals. Combining the proposed algorithm with a recommendation for physical activity provides a powerful tool for the promotion of an active lifestyle in the SCI population, thereby reducing the risk for secondary diseases

Continuous monitoring of vital parameters for clinically valid assessment of human health status

Tese de mestrado integrado, Engenharia Biomédica e Biofísica (Sinais e Imagens Médicas) Universidade de Lisboa, Faculdade de Ciências, 2019The lack of devices suitable for acquiring accurate and reliable measures of patients' physiolog-ical signals in a remote and continuous manner together with the advances in data acquisition technol-ogies during the last decades, have led to the emergence of wearable devices for healthcare. Wearable devices enable remote, continuous and long-term health monitoring in unattended setting. In this con-text, the Swiss Federal Laboratories for Material Science and Technology (Empa) developed a wearable system for long-term electrocardiogram measurements, referred to as textile belt. It consists of a chest strap with two embroidered textile electrodes. The validity of Empa’s system for electrocardiogram monitoring has been proven in a clinical setting. This work aimed to assess the validity of the textile belt for electrocardiogram monitoring in a home setting and to supplement the existing system with sensors for respiratory monitoring. Another objective was to evaluate the suitability of the same weara-ble, as a multi-sensor system, for activity monitoring. A study involving 12 patients (10 males and 2 females, interquartile range for age of 48–59 years and for body mass indexes of 28.0–35.5 kg.m-2) with suspected sleep apnoea was carried out. Overnight electrocardiogram was measured in a total of 28 nights. The quality of recorded signals was assessed using signal-to-noise ratio, artefacts detection and Poincaré plots. Study data were compared to data from the same subjects, acquired in the clinical setting. For respiratory monitoring, optical fibre-based sensors of different geometries were integrated into the textile belt. Signal processing algorithms for breathing rate and tidal volume estimation based on respiratory signals acquired by the sensors were developed. Pilot studies were conducted to compare the different approaches for respiratory monitoring. The quality of respiratory signals was determined based on signal segments “sinusoidality”, evaluated through the calculation of the cross-correlation between signal segments and segment-specific reference waves. A method for accelerometry-based lying position recognition was proposed, and the proof of concept of activity intensity classification through the combination of subjects’ inertial acceleration, heart rate and breathing rate data, was presented. Finally, a study with three participants (1 male and 2 females, aged 21 ± 2 years, body mass index of 20.3 ± 1.5 kg.m-2) was conducted to assess the validity of the textile belt for respiratory and activity monitoring. Electrocardiogram signals acquired by the textile belt in the home setting were found to have better quality than the data acquired by the same device in the clinical setting. Although a higher artefact percentage was found for the textile belt, signal-to-noise ratio of electrocardiogram signals recorded by the textile belt in the home setting was similar to that of signals acquired by the gel electrodes in the clinical setting. A good agreement was found between the RR-intervals derived from signals recorded in home and clinical settings. Besides, for artefact percentages greater than 3%, visual assessment of Poincaré plots proved to be effective for the determination of the primary source of artefacts (noise or ectopic beats). Acceleration data allowed posture recognition (i.e. lying or standing/sitting, lying position) with an accuracy of 91% and positive predictive value of 80%. Lastly, preliminary results of physical activity intensity classification yielded high accuracy, showing the potential of the proposed method. The textile belt proved to be appropriate for long-term, remote and continuous monitoring of subjects’ physical and physiological parameters. It can monitor not only electrocardiogram, but also breathing rate, body posture and physical activity intensity, having the potential to be used as tool for disease prediction and diagnose support.Contexto: A falta de dispositivos adequados para a monitorização de sinais fisiológicos de um modo remoto e contínuo, juntamente com avanços tecnológicos na área de aquisição de dados nas últimas décadas, levaram ao surgimento de wearable devices, i.e. dispositivos vestíveis, no sector da saúde. Wearable devices possibilitam a monitorização do estado de saúde, de uma forma remota, contínua e de longa duração. Quando feito em ambiente domiciliar, este tipo de monitorização (i.e. contínua, remota e de longa duração) tem várias vantagens: diminui a pressão posta sobre o sistema de saúde, reduz despesas associadas ao internamento e acelera a resposta a emergências, permitindo deteção precoce e prevenção de condições crónicas. Neste contexto, a Empa, Laboratórios Federais Suíços de Ciência e Tecnologia de Materiais, desenvolveu um sistema vestível para a monitorização de eletrocardiograma de longa duração. Este sistema consiste num cinto peitoral com dois elétrodos têxteis integrados. Os elétrodos têxteis são feitos de fio de polietileno tereftalato revestido com prata e uma ultrafina camada de titânio no topo. De modo a garantir a aquisição de sinais de alta qualidade, o cinto tem nele integrado um reservatório de água que liberta vapor de água para humidificar os elétrodos. Este reservatório per-mite a monitorização contínua de eletrocardiograma por 5 a 10 dias, sem necessitar de recarga. A vali-dade do cinto para a monitorização de eletrocardiograma em ambiente clínico já foi provada. Objetivo: Este trabalho teve por objetivo avaliar a validade do cinto para a monitorização de eletrocar-diograma em ambiente domiciliar e complementar o sistema existente com sensores para monitorização respiratória. Um outro objetivo foi analisar a adequação do cinto, como um sistema multisensor, para monitorização da atividade física. Métodos: Um estudo com 12 pacientes com suspeita de apneia do sono (10 homens e 2 mulheres, am-plitude interquartil de 48–59 anos para a idade e de 28.0–35.5 kg.m-2 para o índice de massa corporal) foi conduzido para avaliar a qualidade do sinal de eletrocardiograma medido em ambiente domiciliar. O sinal de eletrocardiograma dos pacientes foi monitorizado continuamente, num total de 28 noites. A qualidade dos sinais adquiridos foi analisada através do cálculo da razão sinal-ruído; da deteção de ar-tefactos, i.e., intervalos RR com um valor inviável de um ponto de vista fisiológico; e de gráficos de Poincaré, um método de análise não linear da distribuição dos intervalos RR registados. Os dados ad-quiridos neste estudo foram comparados com dados dos mesmos pacientes, adquiridos em ambiente hospitalar. Para a monitorização respiratória, sensores feitos de fibra óptica foram integrados no cinto. Al-gorítmicos para a estimar a frequência respiratória e o volume corrente dos sujeitos tendo por base o sinal medido pelas fibras ópticas foram desenvolvidos neste trabalho. As diferentes abordagens foram comparadas através de estudos piloto. Diferentes métodos para avaliação da qualidade do sinal adquirido foram sugeridos. Um método de reconhecimento da postura corporal através do cálculo de ângulos de orientação com base na aceleração medida foi proposto. A prova de conceito da determinação da intensidade da atividade física pela combinação de informações relativas á aceleração inercial e frequências cardíaca e respiratória dos sujeitos, é também apresentada neste trabalho. Um estudo foi conduzido para avaliar a validade do cinto para monitorização da respiração e da atividade física. O estudo contou com 10 parti-cipantes, dos quais 3 vestiram o cinto para monitorização da respiração (1 homem e 2 mulheres, idade 21 ± 2 anos, índice de massa corporal 20.3 ± 1.5 kg.m-2). Resultados: O estudo feito com pacientes com suspeita de apneia do sono revelou que os sinais eletro-cardiográficos adquiridos pelo cinto em ambiente domiciliar foram de melhor qualidade que os sinais adquiridos pelo mesmo dispositivo em ambiente hospitalar. Uma percentagem de artefacto de 2.87% ±4.14% foi observada para os dados adquiridos pelos elétrodos comummente usados em ambiente hospi-talar, 7.49% ± 10.76% para os dados adquiridos pelo cinto em ambiente domiciliar e 9.66% ± 14.65% para os dados adquiridos pelo cinto em ambiente hospitalar. Embora tenham tido uma maior percenta-gem de artefacto, a razão sinal-ruído dos sinais eletrocardiográficos adquiridos pelo cinto em ambiente domiciliar foi semelhante á dos sinais adquiridos pelos elétrodos de gel em ambiente hospitalar. Resul-tados sugerem uma boa concordância entre os intervalos RR calculados com base nos eletrocardiogra-mas registados em ambientes hospitalar e domiciliar. Além disso, para sinais com percentagem de arte-facto superior a 3%, a avaliação visual dos gráficos de Poincaré provou ser um bom método para a determinação da fonte primária de artefactos (batimentos irregulares ou ruído). A monitorização da aceleração dos sujeitos permitiu o reconhecimento da postura corporal (isto é, deitado ou sentado/em pé) com uma exatidão de 91% e valor preditivo positivo de 80%. Por fim, a classificação da intensidade da atividade física baseado na aceleração inercial e frequências cardíaca e respiratória revelou elevada exatidão, mostrando o potencial desta técnica. Conclusão: O cinto desenvolvido pela Empa provou ser apropriado para monitorização de longa-dura-ção de variáveis físicas e fisiológicos, de uma forma remota e contínua. O cinto permite não só monito-rizar eletrocardiograma, mas também frequência respiratória, postura corporal e intensidade da atividade física. Outros estudos devem ser conduzidos para corroborar os resultados e conclusões deste trabalho. Outros sensores poderão ser integrados no cinto de modo a possibilitar a monitorização de outras vari-áveis fisiológicas de relevância clínica. Este sistema tem o potencial de ser usado como uma ferramenta para predição de doenças e apoio ao diagnóstico

A Real-Time and Self-Calibrating Algorithm Based on Triaxial Accelerometer Signals for the Detection of Human Posture and Activity

Assessment of human activity and posture with triaxial accelerometers provides insightful information about the functional ability: classification of human activities, in rehabilitation and elderly surveillance contexts, has been already proposed in the literature. In the meanwhile, recent technological advances allow developing miniaturized wearable devices, integrated within garments, which may extend this assessment to novel tasks, such as real time remote surveillance of workers and emergency operators intervening in harsh environments. We present an algorithm for human posture and activity level detection, based on the real-time processing of the signals produced by one wearable tri-axial-accelerometer. The algorithm is independent of the sensor orientation with respect to the body. Furthermore, it associates to its outputs a "reliability" value representing the classification quality, in order to launch reliable alarms only when effective dangerous conditions are detected. The system was tested on a customized device, to estimate the computational resources needed for real-time functioning. Results exhibit an overall 96.2 % accuracy when classifying both static and dynamic activities