Real-time human ambulation, activity, and physiological monitoring:taxonomy of issues, techniques, applications, challenges and limitations

Automated methods of real-time, unobtrusive, human ambulation, activity, and wellness monitoring and data analysis using various algorithmic techniques have been subjects of intense research. The general aim is to devise effective means of addressing the demands of assisted living, rehabilitation, and clinical observation and assessment through sensor-based monitoring. The research studies have resulted in a large amount of literature. This paper presents a holistic articulation of the research studies and offers comprehensive insights along four main axes: distribution of existing studies; monitoring device framework and sensor types; data collection, processing and analysis; and applications, limitations and challenges. The aim is to present a systematic and most complete study of literature in the area in order to identify research gaps and prioritize future research directions

Fall Prediction and Prevention Systems: Recent Trends, Challenges, and Future Research Directions.

Fall prediction is a multifaceted problem that involves complex interactions between physiological, behavioral, and environmental factors. Existing fall detection and prediction systems mainly focus on physiological factors such as gait, vision, and cognition, and do not address the multifactorial nature of falls. In addition, these systems lack efficient user interfaces and feedback for preventing future falls. Recent advances in internet of things (IoT) and mobile technologies offer ample opportunities for integrating contextual information about patient behavior and environment along with physiological health data for predicting falls. This article reviews the state-of-the-art in fall detection and prediction systems. It also describes the challenges, limitations, and future directions in the design and implementation of effective fall prediction and prevention systems

A Wireless Flexible Sensorized Insole for Gait Analysis

This paper introduces the design and development of a novel pressure-sensitive foot insole for real-time monitoring of plantar pressure distribution during walking. The device consists of a flexible insole with 64 pressure-sensitive elements and an integrated electronic board for high-frequency data acquisition, pre-filtering, and wireless transmission to a remote data computing/storing unit. The pressure-sensitive technology is based on an optoelectronic technology developed at Scuola Superiore Sant'Anna. The insole is a low-cost and low-power battery-powered device. The design and development of the device is presented along with its experimental characterization and validation with healthy subjects performing a task of walking at different speeds, and benchmarked against an instrumented force platform

Augmenting forearm crutches with wireless sensors for lower limb rehabilitation

Forearm crutches are frequently used in the rehabilitation of an injury to the lower limb. The recovery rate is improved if the patient correctly applies a certain fraction of their body weight (specified by a clinician) through the axis of the crutch, referred to as partial weight bearing (PWB). Incorrect weight bearing has been shown to result in an extended recovery period or even cause further damage to the limb. There is currently no minimally invasive tool for long-term monitoring of a patient's PWB in a home environment. This paper describes the research and development of an instrumented forearm crutch that has been developed to wirelessly and autonomously monitor a patient's weight bearing over the full period of their recovery, including its potential use in a home environment. A pair of standard forearm crutches are augmented with low-cost off-the-shelf wireless sensor nodes and electronic components to provide indicative measurements of the applied weight, crutch tilt and hand position on the grip. Data are wirelessly transmitted between crutches and to a remote computer (where they are processed and visualized in LabVIEW), and the patient receives biofeedback by means of an audible signal when they put too much or too little weight through the crutch. The initial results obtained highlight the capability of the instrumented crutch to support physiotherapists and patients in monitoring usage

Static and dynamic accuracy of an innovative miniaturized wearable platform for short range distance measurements for human movement applications

Magneto-inertial measurement units (MIMU) are a suitable solution to assess human motor performance both indoors and outdoors. However, relevant quantities such as step width and base of support, which play an important role in gait stability, cannot be directly measured using MIMU alone. To overcome this limitation, we developed a wearable platform specifically designed for human movement analysis applications, which integrates a MIMU and an Infrared Time-of-Flight proximity sensor (IR-ToF), allowing for the estimate of inter-object distance. We proposed a thorough testing protocol for evaluating the IR-ToF sensor performances under experimental conditions resembling those encountered during gait. In particular, we tested the sensor performance for different (i) target colors; (ii) sensor-target distances (up to 200 mm) and (iii) sensor-target angles of incidence (AoI) (up to 60°). Both static and dynamic conditions were analyzed. A pendulum, simulating the oscillation of a human leg, was used to generate highly repeatable oscillations with a maximum angular velocity of 6 rad/s. Results showed that the IR-ToF proximity sensor was not sensitive to variations of both distance and target color (except for black). Conversely, a relationship between error magnitude and AoI values was found. For AoI equal to 0°, the IR-ToF sensor performed equally well both in static and dynamic acquisitions with a distance mean absolute error <1.5 mm. Errors increased up to 3.6 mm (static) and 11.9 mm (dynamic) for AoI equal to ±30°, and up to 7.8 mm (static) and 25.6 mm (dynamic) for AoI equal to ±60°. In addition, the wearable platform was used during a preliminary experiment for the estimation of the inter-foot distance on a single healthy subject while walking. In conclusion, the combination of magneto-inertial unit and IR-ToF technology represents a valuable alternative solution in terms of accuracy, sampling frequency, dimension and power consumption, compared to existing technologies

Commercially available pressure sensors for sport and health applications: A comparative review

Pressure measurement systems have numerous applications in healthcare and sport. The purpose of this review is to: (a) describe the brief history of the development of pressure sensors for clinical and sport applications, (b) discuss the design requirements for pressure measurement systems for different applications, (c) critique the suitability, reliability, and validity of commercial pressure measurement systems, and (d) suggest future directions for the development of pressure measurements systems in this area. Commercial pressure measurement systems generally use capacitive or resistive sensors, and typically capacitive sensors have been reported to be more valid and reliable than resistive sensors for prolonged use. It is important to acknowledge, however, that the selection of sensors is contingent upon the specific application requirements. Recent improvements in sensor and wireless technology and computational power have resulted in systems that have higher sensor density and sampling frequency with improved usability – thinner, lighter platforms, some of which are wireless, and reduced the obtrusiveness of in-shoe systems due to wireless data transmission and smaller data-logger and control units. Future developments of pressure sensors should focus on the design of systems that can measure or accurately predict shear stresses in conjunction with pressure, as it is thought the combination of both contributes to the development of pressure ulcers and diabetic plantar ulcers. The focus for the development of in-shoe pressure measurement systems is to minimise any potential interference to the patient or athlete, and to reduce power consumption of the wireless systems to improve the battery life, so these systems can be used to monitor daily activity. A potential solution to reduce the obtrusiveness of in-shoe systems include thin flexible pressure sensors which can be incorporated into socks. Although some experimental systems are available further work is needed to improve their validity and reliability

An in-shoe gait analysis device to measure the maximum shear stresses at the first metatarsal head

Bibliography: leaf 107.Recent research indicates that the shear stresses acting on a diabetic's foot are one of the major mechanical contributors to the high incidence of ulceration experienced by these patients. These stresses together with direct pressure are thought to have an effect on blood flow occlusion elsewhere in the body. The reduced blood flow may relate in moderation to reduced tissue tolerance or repair capability or even in more severe cases to cell death. Repeated vascular occlusion in a normal person would produce a minor blister or a swollen area, but with a diabetic patient it has the ability to create large incisions and ulcers. This is because diabetic patients are unable to redistribute the load on their feet due to the lack of sensation in their lower extremities. This results in diabetes being the number one cause of all lower limb amputations and accounting for 50 to 70 % of all non-traumatic amputations in the U.S. In the same country, it accounts for $200 million a year in treatment costs directly related to diabetic foot infections. Quantifying the magnitude and duration of these shear stresses therefore has the potential to play a crucial role in assisting podiatrists and clinicians in their diagnosis and treatment of these patients. However these stresses have not been widely evaluated due to lack of suitable instrumentation for their measurement. A technique which has proven to be the most successful in measuring these stresses involves placing a discrete transducer inside a customised insole and fitting it to a patient's shoe. This report sets out to design a similar technique but with the use of a differently designed transducer. The validity of and confidence in the proposed transducer was established by assessing and comparing the results of the transducer under a series of controlled tests with the results of other transducers presented in the literature. To allow an accurate assessment of the transducer to be made, the tests which were performed on the transducer were controlled and conducted at a fixed walking speed. The computational theory used was based on the assumptions and equations of two dimensional plane strain for linear elastic isotropic homogeneous materials. The transducer is based on the principle that a shear angle is induced on a plane when a shear stress is applied to a plane continuous and orthogonal to it. This principle was adapted into the design of the transducer in the form of a square block of material, whose two orthogonal lateral surfaces were used to measure the shear stress applied to its top surface. The design of the transducer consists of a block of material, two laterally positioned rectangular strain rosettes and a circular base. The first series of tests conducted on the transducer were intended to verify and establish its material properties and characteristics. A model of the transducer was then constructed using the finite element package ABAQUS. Two Shape Factors – one for calibration purposes and the other for in-shoe testing - were generated for the transducer to allow for the effects of the geometrical inconsistencies present in its design to be accounted for. Without these Shape Factors the equations and assumptions of linear elasticity would not have been appropriate. A series of controlled pilot and analysis tests were then performed using the custom designed insole and transducer fitted to a diabetic shoe. The diabetic shoe was worn by a subject who performed the tests on a treadmill at a laboratory in the Sports Institute of South Africa

A new approach to running style analysis using a pressure-sensitive insole device: a small step towards injury prevention

Running-related injuries affect about 50% of runners every year. Our running style could be a contributing factor to the occurrence of these overuse injuries. We used a pressure insole device to observe the effect of running speed on running style, to compare the running style of previously injured and uninjured recreational runners, and to observe the effect of minimalistic vs conventional running shoes. Continuous measurement allowed us to assess variability of running style from one stride to the other, which warrants further investigation in the area of running injury prevention. Prospective follow-up of runners also identified using multiple pairs of running shoes simultaneously and practicing other sports besides running as protective against sustaining an overuse injury

Master of Science

thesisGait analysis is an important tool for diagnosing a wide variety of disorders, with its increasingly accepted benefits culminating in the widespread adoption of motion analysis laboratories. A modern analysis laboratory consists of a multicamera marker tracking system for 3D reconstruction of kinematics and multiple high-fidelity load transducers to determine ground reaction force and enable inverse-dynamics for biomechanics. There is a need for an alternative motion analysis system which does not require a fixed laboratory setting and is lower in cost; freeing the motion capture from the laboratory and reducing the technology costs would enable long-term, home-based, natural monitoring of subjects. This thesis describes two contributions to the end goal of an inexpensive, mobile, insole-based motion analysis laboratory. First is the application of an inertialmeasurement-unit calibration routine and zero-velocity-update algorithm to improve position and orientation tracking. Second is the development, from basic sensor to prototype, of an insole capable of measuring 3 degree-of-freedom ground reaction force. These contributions represent a proof-of-concept that quantitative gait analysis, complete with dynamics, is possible with an insole-based system