Assessment of field rolling resistance of manual wheelchairs

This article proposes a simple and convenient method for assessing the subject-specific rolling resistance acting on a manual wheelchair, which could be used during the provision of clinical service. This method, based on a simple mathematical equation, is sensitive to both the total mass and its fore-aft distribution, which changes with the subject, wheelchair properties, and adjustments. The rolling resistance properties of three types of front casters and four types of rear wheels were determined for two indoor surfaces commonly encountered by wheelchair users (a hard smooth surface and carpet) from measurements of a three-dimensional accelerometer during field deceleration tests performed with artificial load. The average results provided by these experiments were then used as input data to assess the rolling resistance from the mathematical equation with an acceptable accuracy on hard smooth and carpet surfaces (standard errors of the estimates were 4.4 and 3.9 N, respectively). Thus, this method can be confidently used by clinicians to help users make trade-offs between front and rear wheel types and sizes when choosing and adjusting their manual wheelchair.This material was based on work supported by the SACR-FRM project, French National Research Agency (ANR-06-TecSan-020) and the Centre d’Etudeset de Recherche sur l’Appareillage des Handicapés (loaned all MWCs required to fulfill this work

A new manual wheelchair propulsion system with self-locking capability on ramps

A wheelchair user faces many difficulties in their everyday attempts to use ramps, especially those of some length. The present work describes the design and build of a propulsion system for manual wheelchairs for use in ascending or descending long ramps. The design is characterized by a self-locking mechanism that activates automatically to brake the chair when the user stops pushing. The system consists of a planetary transmission with a self-locking capacity coupled to a push rim with which the user moves the system. Different transmission ratios are proposed, adapted to the slope and to the user’s physical capacity (measured as the power the user can apply over ample time periods). The design is shown to be viable in terms of resistance, and approximate dimensions are established for the height and width of the propulsion system. Also, a prototype was built in order to test the self-locking system on ramps

Development of a wheelchair propulsion laboratory

In rehabilitation, sports, and research, wheelchair users can be tested on a new wheelchair ergometer. That is the most important finding of the thesis “Development of a wheelchair propulsion laboratory”. The Esseda ergometer, a roller system made in Groningen, has been improved and tested in the past few years. The study showed that wheelchair propulsion on the ergometer is comparable to driving overground and that the ergometer is capable of adequately measuring various aspects of wheelchair propulsion. Wheelchair users can be tested on the ergometer in their own personalized wheelchair. The ergometer can be used to observe people in rehabilitation and other wheelchair users, so that straining techniques can be detected and adjusted in time. This is important because more than half of the wheelchair users suffer from overuse complaints in the arms and shoulders. The wrists, elbows, and shoulder joint are often areas of complaint. This has a major impact on the lives of wheelchair users, because these joints are used in almost all daily tasks. The ergometer can also be of value in adapted sports. For example, the propulsion technique and physical condition of athletes can be studied in detail. The ergometer can therefore be a valuable addition to the toolset of clinicians, sports coaches, and rehabilitation researchers. By giving the wheelchair ergometer a central place in the wheelchair propulsion lab, the skills of wheelchair users can be improved, wheelchairs can be fitted, and complaints of overload as a result of wheelchair use can be prevented

The assessment of a world-ranked wheelchair sprinter aerodynamics analysis by computer fluid dynamics

Aerodynamics can play an important role in the performance of a wheelchair spinter. The aim of this thesis was to analyse the aerodynamics of a wheelchair sprinter by computer fluid dynamics. This thesis comprises a series of four studies (a review of the literature and three empirical studies). The studies aimed to: (i) review the literature on aerodynamics in wheelchair racing; (ii) compare two different helmets (road vs time trial) at several speeds and head positions by CFD. (iii) assess the aerodynamics in different key-moments of the stroke cycle by CFD; (iv) compare the mechanical power and energy cost of transportation delivered by an elite wheelchair sprinter in key-moments of the stroke cycle. The main conclusions were: (i) there is a lack of research on wheelchair racing aerodynamic’s assess by CFD; (ii) a time trial helmet imposed lower drag keeping a neck hyperextension; (iii) the aerodynamics of a wheelchair racing athlete varied over the different phases of the stroke cycle; (iv) the mechanical power and energy cost in elite wheelchair racing varied in different phases of the stroke cycle. The main conclusion of this thesis was that it is possible to enhance the aerodynamics of a wheelchair sprinter by selecting the best sport garement and equipment, as well as keeping a good body alignment in the key-phases of the stroke cycle.A analise da aerodinâmica desempenha um papel determinante nas provas de velocidade em cadeiras de rodas. Assim, o objetivo desta tese passou por analisar a aerodinâmica de um sujeito das provas de velocidade em cadeiras de rodas, com recurso à análise computacional de fluidos. Para tal, foram realizados quatro estudos, uma revisão de literatura e três estudos empíricos. Foram objetivos dos estudos: (i) rever a literatura quanto ao estudo da aerodinâmica das provas de velocidade em cadeiras de rodas; (ii) comparação de dois capacetes do tipo contrarrelógio e pista em duas posições (olhar em frente e olhar para baixo); (iii) comparação aerodinâmica entre as diferentes fases de um ciclo de puxada com recurso às simulações numéricas; (iv) estimativa da potência mecânica e custo energético num sprinter das provas de velocidade em cadeiras de rodas através de procedimentos analíticos e simulações numéricas. As principais conclusões obtidas foram que: (i) existe pouca literatura e conhecimento acerca das provas de velocidade em cadeiras de rodas, nomeadamente no estudo da aerodinâmica com recurso às simulações numéricas; (ii) os capacetes contrarrelógio são mais efetivos desde que o atleta mantenha o olhar em frente tanto quanto possível; (iii) a aerodinâmica de um atleta das provas de velocidade em cadeiras de rodas variou nas diferentes fases do ciclo de puxada; (iv) a potência mecânica e custo energético foram maiores na fase da pegada, seguida da largada e por fim a fase de recuperação. A principal conclusão desta tese é que torna-se possível melhorar a aerodinâmica de um sujeito das provas de velocidade em cadeiras de rodas através do correto uso do capacete ideal e mantendo tanto quanto possível o alinhamento e sincronização corporal durante as puxadas

Measuring handrim wheelchair propulsion in the lab: a critical analysis of stationary ergometers

There are many ways to simulate handrim wheelchair propulsion in the laboratory. Ideally, these would be able to, at least mechanically, simulate field conditions. This narrative review provides an overview of the lab-based equipment used in published research and critically assesses their ability to simulate and measure wheelchair propulsion performance. A close connection to the field can only be achieved if the instrument can adequately simulate frictional losses and inertia of real-life handrim wheelchair propulsion, while maintaining the ergonomic properties of the wheelchair-user interface. Lab-based testing is either performed on a treadmill or a wheelchair ergometer (WCE). For this study WCEs were divided into three categories: roller, flywheel, and integrated ergometers. In general, treadmills are mechanically realistic, but cannot simulate air drag and acceleration tasks cannot be performed; roller ergometers allow the use of the personal wheelchair, but calibration can be troublesome; flywheel ergometers can be built with commerciallyavailable parts, but inertia is fixed and the personal wheelchair cannot be used; integrated ergometers do not employ the personal wheelchair, but are suited for the implementation of different simulation models and detailed measurements. Lab-based equipment is heterogeneous and there appears to be little consensus on how to simulate field conditions

Drag force mechanical power during an actual propulsion cycle on a manual wheelchair

Revue IRBM : http://www.em-consulte.com/revue/irbm/International audienceThe object of this study was to compute the mechanical power of the resultant braking force during an actual propulsion cycle with a manual wheelchair on the field. The resultant braking force was calculated from a mechanical model taking into account the rolling resistances of the front and rear wheels. Both the resultant braking force and the wheelchair velocity were not constant during the propulsion cycle and varied according to the subject's fore-and-aft and vertical movements in the wheelchair. These variations had logical repercussions on the braking force mechanical power, which ranged from 20.6 to 34.5 W (mean = 29.6 W) during the propulsion cycle. The mechanical power was also calculated from the conditions of a classical drag-test, by the product of the cycle mean velocity and a constant braking force corresponding to a 60 % rear wheels distribution of the subject-and- wheelchair's weight. This second mechanical power (32.4 W) was 10 % higher than the average of the instantaneous power. Beyond the need of a clear definition of the two phases of the propulsion cycle, this study showed that the assumption on wheelchair locomotion usually admitted on laboratory ergometers cannot be applied in field studies, and that the kinetic energy variations during the cycle propulsive phase should be considered for evaluating the subject's mechanical work and power

介助者の自律駆動規範モデルを用いた介助用車いすの補助動力制御

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Analysis of the aerodynamics by experimental testing of an elite wheelchair sprinter

The aim was to compare the resistive forces acting upon an European wheelchair medallist. The coast-down technique was selected to estimate the resistance in the upright position and racing positions with the neck in hyperextension and flexion, respectively. In the upright position, racing position with the neck in flexion and hyperextension the effective surface area was 0.1747, 0.1482 and 0.1456m2, respectively. The coefficient of rolling friction was 0.00119, 0.00489, 0.00618 and the power to overcome drag 26.62, 22.59, 22.19W for the same positions. As a conclusion, the resistance acting upon the sprinter is different according to his position on the chair. Slight changes in the head position over the race can affect by almost 2% the power output