A system and method of encouraging compliance of hand hygiene in an environment where users move from zone to zone and are required to perform hand hygiene between the zones. Users carry a wearable zone sensor which detects zones, detects hand hygiene actions, logs time of changing zones, and hand hygiene actions. The wearable sensor can be integral with a wearable hand hygiene product dispenser and/or can operate in cooperation with a fixed dispenser configured to transmit hand hygiene actions to the wearable zone sensor. The wearable zone sensors are configured to be useable anonymously or to be associated with a user identifier, and to interface with a central computer via a docking station or communication interface to transfer data for later analysis.

Hand hygiene compliance system

There has been increasing interest in applying learning algorithms to improve the dexterity of myoelectric prostheses. In this work, we present a large-scale benchmark evaluation on the second iteration of the publicly released NinaPro database, which contains surface electromyography data for 6 DOF force activations as well as for 40 discrete hand movements. The evaluation involves a modern kernel method and compares performance of three feature representations and three kernel functions. Both the force regression and movement classification problems can be learned successfully when using a nonlinear kernel function, while the exp- χ 2 kernel outperforms the more popular radial basis function kernel in all cases. Furthermore, combining surface electromyography and accelerometry in a multimodal classifier results in significant increases in accuracy as compared to when either modality is used individually. Since window-based classification accuracy should not be considered in isolation to estimate prosthetic controllability, we also provide results in terms of classification mistakes and prediction delay. To this extent, we propose the movement error rate as an alternative to the standard window-based accuracy. This error rate is insensitive to prediction delays and it allows us therefore to quantify mistakes and delays as independent performance characteristics. This type of analysis confirms that the inclusion of accelerometry is superior, as it results in fewer mistakes while at the same time reducing prediction delay.

/pdf/movement-error-rate-for-evaluation-of-machine-learning-3qkpkbcqxm.pdf

Movement Error Rate for Evaluation of Machine Learning Methods for sEMG-Based Hand Movement Classification

Three dimensional inertial sensing of foot movements for automatic tuning of a two-channel implantable drop-foot stimulator

Assessments of stair climbing in real-life situations using an optical tracking system are lacking, as it is difficult to adapt the system for use in and around full flights of stairs. Alternatively, a portable system that consists of inertial measurement units (IMUs) can be used to collect anatomical joint angles during stair ascent. The purpose of this study was to compare the anatomical joint angles obtained by IMUs to those calculated from position data of an optical tracking device. Anatomical joint angles of the thigh, knee and ankle, obtained using IMUs and an optical tracking device, were compared for fourteen healthy subjects. Joint kinematics obtained with the two measurement devices were evaluated by calculating the root mean square error (RMSE) and by calculating a two-tailed Pearson product-moment correlation coefficient (r) between the two signals. Strong mean correlations (range 0.93 to 0.99) were found for the angles between the two measurement devices, as well as an average root mean square error (RMSE) of 4 degrees over all the joint angles, showing that the IMUs are a satisfactory system for measuring anatomical joint angles. These highly portable body-worn inertial sensors can be used by clinicians and researchers alike, to accurately collect data during stair climbing in complex real-life situations.

/pdf/a-portable-system-for-collecting-anatomical-joint-angles-4gt6cfuvj2.pdf

A portable system for collecting anatomical joint angles during stair ascent: a comparison with an optical tracking device

A recent study showed that the gaze patterns of amputee users of myoelectric prostheses differ markedly from those seen in anatomically intact subjects. Gaze behaviour is a promising outcome measures for prosthesis designers, as it appears to reflect the strategies adopted by amputees to compensate for the absence of proprioceptive feedback and uncertainty/delays in the control system, factors believed to be central to the difficulty in using prostheses. The primary aim of our study was to characterise visuomotor behaviours over learning to use a trans-radial myoelectric prosthesis. Secondly, as there are logistical advantages to using anatomically intact subjects in prosthesis evaluation studies, we investigated similarities in visuomotor behaviours between anatomically intact users of a trans-radial prosthesis simulator and experienced trans-radial myoelectric prosthesis users. In part 1 of the study, we investigated visuomotor behaviours during performance of a functional task (reaching, grasping and manipulating a carton) in a group of seven anatomically intact subjects over learning to use a trans-radial myoelectric prosthesis simulator (Dataset 1). Secondly, we compared their patterns of visuomotor behaviour with those of four experienced trans-radial myoelectric prosthesis users (Dataset 2). We recorded task movement time, performance on the SHAP test of hand function and gaze behaviour. Dataset 1 showed that while reaching and grasping the object, anatomically intact subjects using the prosthesis simulator devoted around 90% of their visual attention to either the hand or the area of the object to be grasped. This pattern of behaviour did not change with training, and similar patterns were seen in Dataset 2. Anatomically intact subjects exhibited significant increases in task duration at their first attempts to use the prosthesis simulator. At the end of training, the values had decreased and were similar to those seen in Dataset 2. The study provides the first functional description of the gaze behaviours seen during use of a myoelectric prosthesis. Gaze behaviours were found to be relatively insensitive to practice. In addition, encouraging similarities were seen between the amputee group and the prosthesis simulator group.

/pdf/visuomotor-behaviours-when-using-a-myoelectric-prosthesis-4vss1alhpq.pdf

Visuomotor behaviours when using a myoelectric prosthesis

Comparison of linear accelerations from three measurement systems during "reach & grasp".

Biomechanics for inclusive urban design : effects of tactile paving on older adults’ gait when crossing the street

The efferent control chain for an upper-limb myoelectric prosthesis can be separated into 3 key areas: signal generation, signal acquisition, and device response. Data were collected from twenty trans-radial myoelectric prosthesis users using their own clinically prescribed devices, to establish the relative impact of these potential control factors on user performance (user functionality and everyday prosthesis usage). By identifying the key factor(s), we can guide future developments to ensure clinical impact. Skill in generating muscle signals was assessed via reaction times and signal tracking. To assess the predictability of signal acquisition, we inspected reaction time spread and undesired hand activations. As a measure of device response, we recorded the electromechanical delay between electrode stimulation and the onset of hand movement. Results suggest abstract measures of skill in controlling muscle signals are poorly correlated with performance. Undesired activations of the hand or incorrect responses were correlated with almost all kinematics and gaze measures suggesting unpredictability is a key factor. Significant correlations were also found between several measures of performance and the electromechanical delay; however, unexpectedly, longer electromechanical delays correlated with better performance. Future research should focus on exploring causes of unpredictability, their relative impacts on performance and interventions to address this.

/pdf/addressing-unpredictability-may-be-the-key-to-improving-4yk0cilxzm.pdf

Addressing unpredictability may be the key to improving performance with current clinically prescribed myoelectric prostheses.

The majority of people with upper limb absence (PWULA) live in lower, or middle-income countries (LMICs). However, efforts to develop improved prostheses have largely focused on electrically powered devices, sustainable deployment of which, in LMICs, is difficult. In the ‘Fit-for-purpose, affordable body-powered prostheses’ project, teams from the UK, Uganda and Jordan are developing mechanically-operated prostheses, optimised for LMICs, and establishing local methods for fabrication, fitting and evaluation. Here we first report on preliminary studies aimed at grounding the project in the reality of current prosthetics services and the experiences of people with limb absence in Uganda. Finally, we outline our ongoing work in the context of our findings.
In our first two studies we reviewed current prosthetics and associated repair services. An issue which came up repeatedly was the difficulty faced by orthopaedic technologists in accessing componentry/materials. All specialised prosthetics components and materials are imported, often at a high cost. Purchasing does not appear to be well coordinated between centres, meaning potential economies of scale are not being fully exploited. Although there is supposed to be government funding for prosthetics, in practice budgets are often inadequate and a reliance on donations is common. The resource limitations mean Orthopaedic Technologists often resort to ad-hoc solutions; unsurprisingly perhaps, failures in prostheses were reported. In particular, lamination-based socket manufacture is very difficult, given the complexity (and cost) of the processes involved. Repair services are also limited, in part also due to problems accessing materials/components. Despite (or in part, as a result of) these challenges, the orthopaedic technologists are generally an extremely resourceful and multi-skilled group and there is genuine enthusiasm to see services improve. Further, there is a growth in interest and capabilities in the area of medical device innovation.
In the third of our studies, we interviewed 17 PWULA and present preliminary results from the analysis of a subset of five participants. Firstly, we found that only 2 of the participants reported experience with using an upper limb prosthesis, again supporting the picture which emerged from the other studies. The findings illustrate the emergence of four key themes: a) attitude towards disability; b) barriers to prosthesis use; c) coping without a prosthesis; and d) communication with other PWULA. Although attitudes to those with limb loss varied, participants reported impacts in terms of social isolation and a mixed experience of emotions that appeared predominantly negative; barriers to prosthesis use were broader than just cost and functionality, and included a lack of training and psychological support; given that it is difficult to access an upper limb prosthesis, PWULA have found ways to perform daily life activities without relying on one; finally, most PWULA find the suggestion of communicating with other people with the same experience appealing.
In our project we are addressing some of the issues found in the preliminary studies. To make socket manufacture less dependent on access to imported materials and specialised equipment, we are investigating the development of lattice-style, adjustable sockets, made from locally available materials. We are also investigating alternatives to the traditional harness-controlled, body-powered prosthetic hands. Given that clinicians have no objective means of evaluating the value of the prosthesis to their clients, we are testing the use of low-cost digital monitoring tools. We are also exploring the potential value of using mobile-phones to reduce the isolation of PWULA. Finally, we are exploring how these innovations may be translated into the Ugandan health setting.

Lpj Kenney

Papers

Comparison of linear accelerations from three measurement systems during "reach & grasp".

Biomechanics for inclusive urban design : effects of tactile paving on older adults’ gait when crossing the street

Addressing unpredictability may be the key to improving performance with current clinically prescribed myoelectric prostheses.

Prosthetics services in Uganda : a series of studies to inform the design of a low cost, but fit-for-purpose, body-powered prosthesis

A “virtual sensor” tool to simulate accelerometers for upper limb fes triggering