Establishing user needs for a stability assessment tool to guide wheelchair prescription.

PURPOSE: The WheelSense project aims to develop a system for assessing the stability and performance of wheelchairs through a user-centred design process. This study sought to capture user needs and define the specification for the system. METHOD: A mixed methods approach was adopted. An online survey was completed by 98 participants working in wheelchair provision. The results were built upon through 10 semi-structured interviews and one focus group (n = 5) with professionals working in wheelchair provision in three NHS Trusts in the UK. RESULTS: The results provided a picture of the current UK practice in stability testing. Issues with the reliability and usefulness of the existing methods used to assess the stability and performance of wheelchairs were highlighted. Requirements for a new system were ascertained. These included improved accuracy of tipping angles, features to support record keeping, improved client/carer education support and ability to model or predict client-wheelchair system performance in different configurations. CONCLUSIONS: The paper concludes that there is a need for improved tools to determine the stability of the client-wheelchair system and support the prescription process, to ensure client safety and optimum equipment performance. A list of requirements has been produced to guide the future development of WheelSense. Implications for Rehabilitation The results of this survey and interview-based study present a picture of wheelchair stability testing practices in the UK, and highlight the need for new, more informative methods for guiding wheelchair prescription. The requirements for the design of a new system, or further development of existing tools to support the stability testing and prescription of wheelchairs have been established.

The development and testing of a system for wheelchair stability measurement.

Wheelchair stability has an impact on safety as well as wheelchair performance, propulsion and manoeuvrability. Wheelchair stability is affected by the addition of life-supporting heavy equipment, e.g. ventilators and oxygen cylinders, as well as the characteristics of the user e.g. limb amputations, obesity. The aim of the research described here was to develop and test a stability assessment system that would guide and support the adjustment of wheelchairs to individual needs, characteristics and lifestyles. The resulting system provides assessment of centre of gravity and wheelchair stability and calculates the wheelchair tipping angles. The system consists of a force platform that senses the weight distribution of the wheelchair and calculates the centres of the contact points of the wheels and the distances between them. The measurement data are transferred via a WiFi connection to a portable tablet computer where wheelchair stability parameters are calculated. A touchscreen GUI provides visualization of the stability results and navigation through the measurement modes. The developed new concept has been evaluated through technical laboratory-based testing to determine the validity of the data collected. Initial testing has been undertaken within the clinical setting in 3 large hospitals in the UK. Initial results suggest that Wheelsense® provides a valuable tool to support clinical judgement.

Gait generation for powered Hip-Ankle-Linkage-Orthosis.

A hip-knee-ankle-foot orthotic system called `HALO'(Hip and Ankle Linked Orthosis) for paraplegic walking has been developed in our previous study. Each ankle joint of the HALO system is linked with a medial single joint via a wire which allows both feet of the orthosis to stay always parallel to the floor during walking and assists swinging the leg. The tests of the HALO system demonstrated that it allows smoother walking and easy don/doff. In order to improve further the characteristics of the previous design, we started a new project called pHALO aiming at further reducing of the energy expenditure during walking. As a difference from the previous solution where ankle joints were restrained, the new solution will incorporate two actuators to control the ankle joints angles. As an intermediate step from the development of the pHALO system, in this study we added to the existing system a feedback PI controller to control the ankle joint angle of the right foot in the push-off phase and conducted an experiment to evaluate the effect of the new design on the walking patterns and energy efficiency. The results showed longer stride length, faster gait speed, smaller variation of the CoG, and less energy consumption.

Tongue motor training support system.

In this paper, we introduce a new tongue-training system that can be used for improvement of the tongue's range of motion and muscle strength after dysphagia. The training process is organized in game-like manner. Initially, we analyzed surface electromyography (EMG) signals of the suprahyoid muscles of five subjects during tongue-training motions. This test revealed that four types tongue training motions and a swallowing motion could be classified with 93.5% accuracy. Recognized EMG signals during tongue motions were designed to allow control of a mouse cursor via intentional tongue motions. Results demonstrated that simple PC games could be played by tongue motions, achieving in this way efficient, enjoyable and pleasant tongue training. Using the proposed method, dysphagia patients can choose games that suit their preferences and/or state of mind. It is expected that the proposed system will be an efficient tool for long-term tongue motor training and maintaining patients' motivation.

An approach to measure wheelchair stability. Concept and benefits.

Wheelchair stability is dependent on user's body characteristics that can shift significantly the original center of mass in the cases of limb amputation, severe skeletal deformities or obesity. The center of gravity may change with the installation of additional devices such as oxygen cylinders or ventilators on the wheelchair. Therefore, quantitative evaluation and prediction of the behavior of the user-wheelchair system in a variety of static and dynamic situations is essential for user's safety and for the optimal tuning of the human-wheelchair system. In this paper we discuss an approach for wheelchair stability assessment that only requires two inclinations and weight measurements. We also discuss the algorithm associated to the procedure based on the use of the reaction forces in the contact points of the wheels measured by the load cells. Further, the paper includes an analysis of the influence of the errors in measurement of the input parameters on the output results and demonstrates that the proposed approach possesses high accuracy. The advantage of the proposed approach is the use of a reliable procedure based on three simple steps and five weight measurements with four independent load scales which may lead to the design of an affordable and accurate measurement system.

Simulation model of a lever-propelled wheelchair.

Wheelchair efficiency depends significantly on the individual adjustment of the wheelchair propulsion interface. Wheelchair prescription involves reconfiguring the wheelchair to optimize it for specific user characteristics. Wheelchair tuning procedure is a complicated task that is performed usually by experienced rehabilitation engineers. In this study, we report initial results from the development of a musculoskeletal model of the wheelchair lever propulsion. Such a model could be used for the development of new advanced wheelchair approaches that allow wheelchair designers and practitioners to explore virtually, on a computer, the effects of the intended settings of the lever-propulsion interface. To investigate the lever-propulsion process, we carried out wheelchair lever propulsion experiments where joint angle, lever angle and three-directional forces and moments applied to the lever were recorded during the execution of defined propulsion motions. Kinematic and dynamic features of lever propulsion motions were extracted from the recorded data to be used for the model development. Five healthy male adults took part in these initial experiments. The analysis of the collected kinematic and dynamic motion parameters showed that lever propulsion is realized by a cyclical three-dimensional motion of upper extremities and that joint torque for propulsion is maintained within a certain range. The synthesized propulsion model was verified by computer simulation where the measured lever-angles were compared with the angles generated by the developed model simulation. Joint torque amplitudes were used to impose the torque limitation to the model joints. The results evidenced that the developed model can simulate successfully basic lever propulsion tasks such as pushing and pulling the lever.

Toward gesture controlled wheelchair: a proof of concept study.

This study focuses on the early stages of developing and testing an interactive approach for gesture-based wheelchair control that could facilitate the user in various tasks such as cooking and food serving. The proposed method allows a user to hold an object (tray, saucepan, etc) with both hands and to control at the same time the wheelchair direction via changing the position of his/her arms. The wheelchair control system contains an image sensor directed to the user's arms. Sensor signals are processed via an image-recognition algorithm and the calculations for the arm positions are used for the computation of the wheelchair steering signals. Thus, the wheelchair direction depends on the arm positions and the user can control the wheelchair by moving his/her arms. An initial wheelchair prototype, operated by the intentional motions of one hand, was built and was tested by several initial experiments.

Surveillance of foot-and-mouth disease (FMD) in susceptible wildlife and domestic ungulates in Southeast of Bulgaria following a FMD case in wild boar.

Following a foot-and-mouth disease (FMD) case of serotype O in wild boar in Southeast of Bulgaria, notified in January 2011 and eleven FMD outbreaks in livestock, a control and eradication plan according to the EU legislation was implemented. Based on the epidemiological considerations a "Cordon Sanitaire" along the border to Turkey, consisting of a defined infected area (1240 km(2)) and two areas of risk (2160 km(2)) was established. Within these areas a total of 812 wild boar, 68 roe deer, 7 red deer and 2 mouflons, hunted between February 2011 and January 2012, were tested for the presence of FMD. No FMD virus could be detected. Seropositive animals were found in wild boar (6.9%) and roe deer (4.4%), most of them spatially clustered around the FMD outbreaks in livestock, limited within a radius of 20 km. The outbreaks in domestic ungulates were controlled in the framework of EU legislation, including stamping out, standstill and no use of vaccination. All villages within the Cordon Sanitaire were examined for the presence of FMD according to the control and eradication plan. Neither clinical signs nor seroconversion was detected and the region could regain its status of FMD freedom without vaccination. The relatively low seroprevalence and clustered spatial distribution of seropositive wild boar and roe deer suggest that the FMD infection in wildlife was mainly a short living event, which failed to develop into a large scale epidemic.

Improving wheelchair prescription: an analysis of user needs and existing tools.

Wheelchair users experience many situations that affect the stability and associated performance of their wheelchair. Stability is affected by user characteristics and abilities, environmental features and conditions, and wheelchair modification and accessories. Wheelchair prescribers need effective tools and methods to provide quantitative evaluation and prediction of the behavior of the user-wheelchair system in a variety of static and dynamic situations. Such information is very important to guide efficient management of associated risks and adjust chairs accordingly. This project involves a user-centered approach for design and evaluation of a load cell based wheelchair stability assessment system (Wheel-SAS). Here, the current methods for assessing stability are described, and their shortcomings explained. The user-centered design approach being applied to the development of the associated Wheel-SAS hardware and software is described. Future work including semi-structured interviews and an online survey with wheelchair prescribers and associated healthcare professionals for deriving user requirements and a design specification for a load cell system for measuring dynamic wheelchair stability are detailed.

Robotic wheelchair control interface based on headrest pressure measurement.

We introduce a novel approach for proportional head control for robotic wheelchairs. An array of force sensors embedded into the headrest is used to monitor the pressure distribution changes due to the intentional head motions of the patient. The force signals are analysed and converted into fully proportional signals that control the wheelchair direction and speed. We developed a prototype interface that generates signals similar to the signals of a standard joystick control box and connected the new interface to a standard Invacare wheelchair. Tests showed that all users adapted to the control algorithm very quickly and were able to follow very precisely complex target trajectories on various speeds. The interface does not require any attachments to the user's head and does not cause any limitation of the user's field of view.

The smart house for older persons and persons with physical disabilities: structure, technology arrangements, and perspectives.

Smart houses are considered a good alternative for the independent life of older persons and persons with disabilities. Numerous intelligent devices, embedded into the home environment, can provide the resident with both movement assistance and 24-h health monitoring. Modern home-installed systems tend to be not only physically versatile in functionality but also emotionally human-friendly, i.e., they may be able to perform their functions without disturbing the user and without causing him/her any pain, inconvenience, or movement restriction, instead possibly providing him/her with comfort and pleasure. Through an extensive survey, this paper analyzes the building blocks of smart houses, with particular attention paid to the health monitoring subsystem as an important component, by addressing the basic requirements of various sensors implemented from both research and clinical perspectives. The paper will then discuss some important issues of the future development of an intelligent residential space with a human-friendly health monitoring functional system.