A system for estimating motion parameters corresponding to a user. The system may generally include a receiver operable to receive a signal from an external source, an inertial sensor operable to be coupled with the user and arbitrarily oriented relative to the direction of user motion for generation of a signal corresponding to user motion, and a processing system in communication with the receiver and inertial sensor. The processing system can be operable to utilize the receiver signal to estimate a first parameter corresponding to a first motion parameter type, utilize the inertial sensor signal to estimate a second parameter corresponding to a second motion parameter type, generate a user-specific motion model to correlate the first parameter type and second parameter type using at least the first and second estimated parameters, utilize the inertial sensor signal to estimate a third parameter corresponding to the second parameter type, and utilize the motion model and the third parameter to estimate a fourth parameter corresponding to the first parameter type independent of the receiver signal.

Method and apparatus for estimating a motion parameter

Accurate measurement of physical activity is a pre-requisite to monitor population physical activity levels and design effective interventions. Global Positioning System (GPS) technology offers potential to improve the measurement of physical activity. This paper 1) reviews the extant literature on the application of GPS to monitor human movement, with a particular emphasis on free-living physical activity, 2) discusses issues associated with GPS use, and 3) provides recommendations for future research. Overall findings show that GPS is a useful tool to augment our understanding of physical activity by providing the context (location) of the activity and used together with Geographical Information Systems can provide some insight into how people interact with the environment. However, no studies have shown that GPS alone is a reliable and valid measure of physical activity.

/pdf/global-positioning-system-a-new-opportunity-in-physical-lflijfvqdl.pdf

Global positioning system: a new opportunity in physical activity measurement.

A motion sensing apparatus generally comprising a housing unit operable to be attached to an object at an attachment position, an accelerometer operable to provide a signal corresponding to an acceleration measurement; and a processing system. The processing system is operable to acquire the signal corresponding to the acceleration measurement and analyze the acquired acceleration measurement to identify the attachment position of the housing unit.

Method and apparatus for determining the attachment position of a motion sensing apparatus

Heart rate variability (HRV), the changes in the beat-to-beat heart rate calculated from the electrocardiogram (ECG), is a key indicator of an individual's cardiovascular condition. Assessment of HRV has been shown to aid clinical diagnosis and intervention strategies. However, the variety of HRV estimation methods and contradictory reports in this field indicate that there is a need for a more rigorous investigation of these methods as aids to clinical evaluation. This thesis investigates the development of appropriate HRV signal processing techniques in the context of pilot studies in two fields of potential application, sleep and head-up tilting (HUT). A novel method for characterising normality in the ECG using both timing information and morphological characteristics is presented. A neural network, used to learn the beat-to-beat variations in ECG waveform morphology, is shown to provide a highly sensitive technique for identifying normal beats. Fast Fourier Transform (FFT) based frequency-domain HRV techniques, which require re-sampling of the inherently unevenly sampled heart beat time-series (RR tachogram) to produce an evenly sampled time series, are then explored using a new method for producing an artificial RR tachogram. Re-sampling is shown to produce a significant error in the estimation of an (entirely specified) artificial RR tachogram. The Lomb periodogram, a method which requires no re-sampling and is applicable to the unevenly sampled nature of the signal is investigated. Experiments demonstrate that the Lomb periodogram is superior to the FFT for evaluating HRV measured by the LF/HF-ratio, a ratio of the low to high frequency power in the RR tachogram within a specified band (0.04-0.4 Hz). The effect of adding artificial ectopic beats in the RR tachogram is then considered and it is shown that ectopic beats significantly alter the spectrum and therefore must be removed or replaced. Replacing ectopic beats by phantom beats is compared to the case of ectopic-realted RR interval removal for the FFT and Lomb methods for varying levels of ectopy. The Lomb periodogram is shown to provide a signficantly better estimate of the LF/HF- ratio under these conditions and is a robust method for measuring the LF/HF-ratio in the presence of (a possibly unknown number of) ectpoic beats or artefacts. The Lomb peridogram and FFT-based techniques are applied to a database of sleep apnoeic and normal subjects. A new method of assessing HRV during sleep is proposed to minimise the confounding effects on HRV of changes due to changing mental activity. Estimation of LF/HF-ratio using the Lomb technique is shown to separate these two patient groups more effectively than with FFT-based techniques. Results are also presented for the application of these methods to controlled (HUT) studies on subjects with syncope, an autonomic nervous system problem, which indicate that the techniques developed in this thesis may provide a method for differentiating between sub-classes of syncope.

Signal processing methods for heart rate variability

Wavelet cross-correlation (WCC) is used to analyse the relationship between low-frequency oscillations in near-infrared spectroscopy (NIRS) measured cerebral oxyhaemoglobin (O2Hb) and mean arterial blood pressure (MAP) in patients suffering from autonomic failure and age-matched controls. Statistically significant differences are found in the wavelet scale of maximum cross-correlation upon posture change in patients, but not in controls. We propose that WCC analysis of the relationship between O2Hb and MAP provides a useful method of investigating the dynamics of cerebral autoregulation using the spontaneous low-frequency oscillations that are typically observed in both variables without having to make the assumption of stationarity of the time series. It is suggested that for a short-duration clinical test previous transfer-function-based approaches to analyse this relationship may suffer due to the inherent nonstationarity of low-frequency oscillations that are observed in the resting brain.

/pdf/synchronization-between-arterial-blood-pressure-and-cerebral-5gt3qcs6rf.pdf

Synchronization between arterial blood pressure and cerebral oxyhaemoglobin concentration investigated by wavelet cross-correlation

Background. The present study was aimed at clarifying the mechanism of orthostatic hypotension (OH) that occurs in elderly persons and at investigating assisting methods to prevent OH by evaluating changes in autonomic nervous system (ANS) activity and cerebral circulation of elderly persons when engaged in passive standing. Methods. Eight elderly volunteers and 9 young volunteers gave informed consent to participate in the study. Two experimental conditions were established: (i) “active standing,” in which the subjects stood on their own with guidance from an assistant, and (ii) “passive standing,” in which the subjects were placed in a standing position completely by an assistant. ANS was determined before and after standing by measuring the heart rate variability. The reaction of the ANS was evaluated on the basis of low-frequency power (LF: 0.05‐0.15 Hz) and high-frequency power (HF: 0.15‐0.4 Hz), which were separated from the R-R interval data by power spectral analysis using the fast Fourier transformation. Cerebral perfusion was measured over the right frontal region using a near-infrared spectroscopy cerebral oxygen monitor. Results. The main findings were: (i) Transient decreases in blood pressure occurred immediately after standing in both the young and elderly subjects. (ii) The LF:HF ratio increased significantly ( p , .05) immediately after active standing in the young subjects, whereas this ratio increased in the elderly subjects after some delay. (iii) The LF:HF ratio increased significantly ( p , .01) immediately after passive standing in the young subjects, whereas this ratio decreased significantly ( p , .05) in the elderly subjects. (iv) In the elderly subjects, the total hemoglobin (HbT) and oxyhemoglobin showed the greatest decrease during the 15-second period after standing. The maximum changes in the HbT with passive standing differed significantly ( p , .01) from those observed during active standing. Conclusions. Our findings emphasize the need to devise bioengineered means that allow elderly persons to exert themselves, to maintain or improve muscle contractility and ANS function, while providing minimum assistance for standing.

Orthostatic Hypotension in Elderly Persons During Passive Standing A Comparison With Young Persons

PROBLEM TO BE SOLVED: To provide a sleeping depth estimation device which can estimate a sleeping depth with high precision without restraint. SOLUTION: The sleeping depth estimation device is equipped with a biological information sensor 2 which detects biological information, a vital information processing circuit 3 which detects a plurality of basic data on sleeping depth including heart rate, standard deviation of heart rate, respiration rate, standard deviation of respiration rate and body movement rate through signals from the biological information sensor 2 and a sleeping depth estimation circuit 4 which repeats sleeping depth estimation processing based on the basic data on sleeping depth obtained from the biological information processing circuit 3. The sleeping depth estimation circuit 4 performs estimation processing which is a combination of discrimination analysis and a state transition probability model to the basic data on sleeping depth determined from the biological information processing circuit 3. COPYRIGHT: (C)2004,JPO

Sleeping depth estimation device and bedding equipped with the same

As an application of an ambulatory biosignal memory device, we have developed a portable jogging monitoring device and studied its application for health management here. This device is a micro processor based system with some sensors necessary to monitor condition of the user during jogging, that is, a heart rate sensor, a GPS sensor and a physical activity sensor. We also have developed PC based health management software that receives jogging data after jogging and stores it as a long term jogging trend data. From these long term data it feeds back the distance completion of jogging on the virtual course. Moreover it can show the trend of jogging time, distance, average heart rate and the user can know his / her own health condition.

Jogging support system with portable monitoring device and health manage software.

Daily monitoring of heart rates is important in health management. Many researchers have analysed heart rate variability by using the resting heart rate because such an analysis can facilitate the early discovery of a variety of illnesses and health conditions. Some problems that arise in measuring heart rate are the feeling of confinement. Therefore, we required a system that could measure the resting heart rate in a static position in such a way that the subject is completely unaware that the measurement is being recorded. We propose a non-restrictive measurement method that uses only an acceleration sensor placed inside a down quilt. This method is easy for home use. The acceleration sensor was placed inside the quilt such that it was positioned opposite to the left-hand side of the subject's chest. Six healthy subjects were requested to lie in the supine position and were covered with the quilt equipped with the acceleration sensor. Mechanical vibrations that resulted from heart activity were carried through the quilt to the acceleration sensor. As a result, periodic vibrations were measured successfully, and in the six subjects, these vibrations were proved to be highly correlated with the R wave of electrocardiograms. The same results were obtained even when the subjects were lying in the left lateral position. The results indicated that our new method, which used an acceleration sensor placed inside a down quilt, was simple and could be used to measure the resting heart rate in a lying position.

/pdf/proposal-for-a-method-of-non-restrictive-measurement-of-14injs2zv2.pdf

Proposal for a Method of Non-restrictive Measurement of Resting Heart Rate in a Lying Position

We have developed a portable jogging monitoring device and studied its application for health management. This device is a micro processor based system with some sensors necessary to monitor the health condition of the user during jogging, that is, a heart rate sensor, a GPS sensor and a physical activity sensor. We also have developed PC based health management software, that receives jogging data from the portable device and stores it as a long term jogging trend data. From these long term data it can feedback the distance completion of jogging on the virtual course. Moreover it can show the trend of jogging time, distance, average heart rate and the user can know his/her own health condition.

Takeo Iida

Papers

Orthostatic Hypotension in Elderly Persons During Passive Standing A Comparison With Young Persons

Sleeping depth estimation device and bedding equipped with the same

Jogging support system with portable monitoring device and health manage software.

Proposal for a Method of Non-restrictive Measurement of Resting Heart Rate in a Lying Position

Portable jogging monitor device and its application for health management