Bert-Jan van Beijnum

Objective Evaluation of the Quality of Movement in Daily Life after Stroke

Background Stroke survivors are commonly left with disabilities that impair activities of daily living. The main objective of their rehabilitation program is to maximize the functional performance at home. However, the actual performance of patients in their home environment is unknown. Therefore, objective evaluation of daily life activities of stroke survivors in their physical interaction with the environment is essential for optimal guidance of rehabilitation therapy. Monitoring daily life movements could be very challenging, as it may result in large amounts of data, without any context. Therefore, suitable metrics are necessary to quantify relevant aspects of movement performance during daily life. The objective of this study is to develop data processing methods, which can be used to process movement data into relevant metrics for the evaluation of intra-patient differences in quality of movements in a daily life setting. Methods Based on an iterative requirement process, functional and technical requirements were formulated. These were prioritized resulting in a coherent set of metrics. An activity monitor was developed to give context to captured movement data at home. Finally, the metrics will be demonstrated in two stroke participants during and after their rehabilitation phases. Results By using the final set of metrics, quality of movement can be evaluated in a daily life setting. As example to demonstrate potential of presented methods, data of two stroke patients were successfully analyzed. Differences between in-clinic measurements and measurements during daily life are observed by applying the presented metrics and visualization methods. Heel height profiles show intra-patient differences in height, distance, stride profile, and variability between strides during a 10-m walk test in the clinic and walking at home. Differences in distance and stride profile between both feet were larger at home, than in clinic. For the upper extremities, the participant was able to reach further away from the pelvis and cover a larger area. Discussion Presented methods can be used for the objective evaluation of intra-patient differences in movement quality between in-clinic and daily life measurements. Any observed progression or deterioration of movement quality could be used to decide on continuing, stopping, or adjusting rehabilitation programs.

Context-aware middleware architecture for vertical handover support to multi-homed nomadic mobile services

To accommodate the requirements such as high usability and personalization of 4G (mobile) networks, conventional handheld single network-interface mobile devices are evolving into multi-homed devices. Moreover, owing to the recent advances in the mobile middleware technologies, hardware technologies and association with the human user, handheld mobile devices are evolving into data producers and in turn acting as Nomadic Mobile Service (NMS) providers. For these devices, a vertical handover support is essential for the improved and reliable NMS delivery. Also, the fulfillment of the required QoS by the NMS is bounded by the end-to-end QoS (e2eQoS) provided by the underlying heterogeneous networks. To deal with these aspects, we propose a context-aware middleware architecture supporting vertical handover for the NMSs hosted on the handheld mobile devices. We emphasize the following features of the proposed middleware: 1) Context-aware computing based approach which uses an extensive set of context information collected from the mobile device and a fixed network; 2) Provisioning of and interaction with the end-to-end QoS (e2eQoS) predictions context source in the fixed network to obtain near-accurate estimation of the e2eQoS at a certain geographic location and to reduce unnecessary power usage in searching for available networks.

Towards Location Based QoS-Aware Network Selection Mechanism for the Nomadic Mobile Services

The advances in the area of location based computing will soon make it feasible to predict the availability of wireless networks and their application level Quality of Service (QoS) characteristics along the location and time dimensions. Such predictions are referred to as QoS predictions which are provided by the QoS Context Source (QoSCS) hosted in the fixed network. Herewith we present a network selection mechanism on the mobile device which requests QoS predictions as needed and uses these predictions combined with the current location and time to select the wireless network which satisfies QoS requirements of the services hosted on a mobile device. We evaluate the performance of the proposed scheme using simulations and compare the results with the other mechanism that only uses information locally available on the mobile device for the network selection. The results obtained from the simulations encourage further system development and prototyping.

Ambulatory Estimation of Relative Foot Positions by Fusing Ultrasound and Inertial Sensor Data

Relative foot position estimation is important for rehabilitation, sports training and functional diagnostics. In this paper an extended Kalman filter fusing ultrasound range estimates and inertial sensors is described. With this filter several gait parameters can be estimated ambulatory. Step lengths and stride widths from 54 walking trials of three healthy subjects were estimated and compared to an optical reference. Mean ( ± standard deviation) of absolute difference was 1.7 cm ( ±1.8 cm) and 1.2 cm ( ±1.2 cm) for step length and stride width respectively. Walking with a turn and walking around in a square area were also investigated and resulted in mean absolute differences of 1.7 cm ( ±2.0 cm) and 1.5 cm ( ±1.5 cm) for step lengths and stride widths. In addition to these relative positions, velocities, orientations and stance and swing times can also be estimated. We conclude that the presented system is low-cost and provides a complete description of footstep kinematics and timing.

Ambulatory assessment of walking balance after stroke using instrumented shoes

BackgroundFor optimal guidance of walking rehabilitation therapy of stroke patients in an in-home setting, a small and easy to use wearable system is needed. In this paper we present a new shoe-integrated system that quantifies walking balance during activities of daily living and is not restricted to a lab environment. Quantitative parameters were related to clinically assessed level of balance in order to assess the additional information they provide.MethodsData of 13 participants who suffered a stroke were recorded while walking 10 meter trials and wearing special instrumented shoes. The data from 3D force and torque sensors, 3D inertial sensors and ultrasound transducers were fused to estimate 3D (relative) position, velocity, orientation and ground reaction force of each foot. From these estimates, center of mass and base of support were derived together with a dynamic stability margin, which is the (velocity) extrapolated center of mass with respect to the front-line of the base of support in walking direction. Additionally, for each participant step lengths and stance times for both sides as well as asymmetries of these parameters were derived.ResultsUsing the proposed shoe-integrated system, a complete reconstruction of the kinematics and kinetics of both feet during walking can be made. Dynamic stability margin and step length symmetry were not significantly correlated with Berg Balance Scale (BBS) score, but participants with a BBS score below 45 showed a small-positive dynamic stability margin and more asymmetrical step lengths. More affected participants, having a lower BBS score, have a lower walking speed, make smaller steps, longer stance times and have more asymmetrical stance times.ConclusionsThe proposed shoe-integrated system and data analysis methods can be used to quantify daily-life walking performance and walking balance, in an ambulatory setting without the use of a lab restricted system. The presented system provides additional insight about the balance mechanism, via parameters describing walking patterns of an individual subject. This information can be used for patient specific and objective evaluation of walking balance and a better guidance of therapies during the rehabilitation.Trial registrationThe study protocol is a subset of a larger protocol and registered in the Netherlands Trial Registry, number NTR3636.

Usability evaluations of a wearable inertial sensing system and quality of movement metrics for stroke survivors by care professionals

Background Inertial motion capture systems are used in many applications such as measuring the movement quality in stroke survivors. The absence of clinical effectiveness and usability evidence in these assistive technologies into rehabilitation has delayed the transition of research into clinical practice. Recently, a new inertial motion capture system was developed in a project, called INTERACTION, to objectively measure the quality of movement (QoM) in stroke survivors during daily-life activity. With INTERACTION, we are to be able to investigate into what happens with patients after discharge from the hospital. Resulting QoM metrics, where a metric is defined as a measure of some property, are subsequently presented to care professionals. Metrics include for example: reaching distance, walking speed, and hand distribution plots. The latter shows a density plot of the hand position in the transversal plane. The objective of this study is to investigate the opinions of care professionals in using these metrics obtained from INTERACTION and its usability. Methods By means of a semi-structured interview, guided by a presentation, presenting two patient reports. Each report includes several QoM metric (like reaching distance, hand position density plots, shoulder abduction) results obtained during daily-life measurements and in clinic and were evaluated by care professionals not related to the project. The results were compared with care professionals involved within the INTERACTION project. Furthermore, two questionnaires (5-point Likert and open questionnaire) were handed over to rate the usability of the metrics and to investigate if they would like such a system in their clinic. Results Eleven interviews were conducted, where each interview included either two or three care professionals as a group, in Switzerland and The Netherlands. Evaluation of the case reports (CRs) by participants and INTERACTION members showed a high correlation for both lower and upper extremity metrics. Participants were most in favor of hand distribution plots during daily-life activities. All participants mentioned that visualizing QoM of stroke survivors over time during daily-life activities has more possibilities compared to current clinical assessments. They also mentioned that these metrics could be important for self-evaluation of stroke survivors. Discussion The results showed that most participants were able to understand the metrics presented in the CRs. For a few metrics, it remained difficult to assess the underlying cause of the QoM. Hence, a combination of metrics is needed to get a better insight of the patient. Furthermore, it remains important to report the state (e.g., how the patient feels), its surroundings (outside, inside the house, on a slippery surface), and detail of specific activities (does the patient grasps a piece of paper or a heavy cooking pan but also dual tasks). Altogether, it remains a questions how to determine what the patient is doing and where the patient is doing his or her activities.

Interactive scenario visualization for user-based service development

Scenarios are commonly used to develop new systems in multidisciplinary projects. However, written scenarios are sequential, not dynamic and often too abstract or difficult to understand for end users. The goal of this paper hence is to extend the use of scenarios in design methodologies, using an interactive scenario visualization (ISV) approach. After discussing scenario-based design, we show that ISV can be used beneficially to develop a new ICT system and that ISV aids in reflection upon the design trajectory. Comparing two software platforms, we found it was possible to develop such ISVs inexpensively, rapidly and with good visual quality. As a case study, we demonstrate the use of a home care telemedicine system in 3D for discussion and development purposes1. An evaluation among n=22 professionals illustrates that ISVs can prove useful in design, aid in clarification of new systems, are suitable to demonstrate system functionalities, and aid in articulating feedback. Finally, we discuss generalization of the use of ISVs.

Context-Aware Computing Support for Network-Assisted Seamless Vertical Handover in Remote Patient Monitoring

The advances in the area of mobile computing is likely to make it feasible to predict the availability of wireless networks and their application level Quality of Service (QoS) characteristics along the user mobility path. Such predictions are referred to as QoS predictions which are provided by the QoS Context Source (QoSCS) hosted in the fixed network. On the multi-homed mobile devices, the QoS Predictions could be used for the handover to the optimal wireless network which satisfies the QoS requirements of the mobile applications. However, to achieve this functionality, a middleware support is necessary to obtain and make use of QoS predictions in real-time. To this end, we present design, architecture and validation of the context-aware computing support for network-assisted seamless vertical handover that uses QoS predictions to take a handover decision. We evaluate the proposed solution, in a case where it is applied in the mobile health care applications. The obtained simulation results encourage us to conduct the real-time system validation by employing the proposed solution.

A*-Based Task Assignment Algorithm for Context-Aware Mobile Patient Monitoring Systems

Mobile Patient Monitoring System (MPMS) is positioned to provide high quality healthcare services in the near future. The gap between its application demands and resource supplies, however, still remains and may hinder this process. Dynamic context-aware adaptation mechanisms are required in order to meet the stringent requirements on such mission critical applications. The fundamental model underlying an MPMS includes a set of biosignal data processing tasks distributed across a set of networked devices. In our earlier work, we designed and validated a task distribution framework to support dynamic system reconfiguration of MPMS by means of task redistribution. This paper focuses on its decision-making component that can calculate the optimal task assignment by taking into account the reconfiguration costs. This paper has three major contributions. Firstly, we study a context-aware scenario and derive the design requirements for a task assignment algorithm in MPMS. Secondly, using a graph-based system model, we proposed an A*-based task assignment algorithm that minimizes the system end-to-end delay while guaranteeing required system battery lifetime and availability. We introduce a set of node expansion rules and a pre-processing procedure to calculate the heuristic function (

Design of an Online Charging System to Support IMS-Based Inter-domain Composite Services

h(n)