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Rehabilitation Engineering, IEEE Transactions on

Issue 3 • Date Sept. 1996

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Displaying Results 1 - 11 of 11
  • Guest Editorial Special Section on Wheeled Mobility

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    Freely Available from IEEE
  • The study of kinematic transients in locomotion using the integrated kinematic sensor

    Page(s): 193 - 200
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    A system based on the integrated kinematic sensor (IKS) was used to study the three-dimensional (3-D) kinematics of human lower limb during walking and running. The linear displacement, angular velocity, and linear acceleration of the foot, shank, and thigh segments were directly measured using three IKSs. The results clearly showed the heel strike impact in both walking and running, illustrating the high frequency components that exist in those activities. This paper illustrates the limitations of standard position measurements to capture transients associated with phase transitions, not only in acceleration estimates, but also in the determination of segmental angular velocities. An error analysis was conducted to determine the relative contribution of the accelerometer and the angular rate sensor to the determination of the segmental center of mass (COM) acceleration. The results suggest that in practical kinesiological applications, adding either an accelerometer or an angular rate sensor can remarkably increase the accuracy of segmental COM-acceleration estimates View full abstract»

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  • Three-dimensional kinematics of wheelchair propulsion

    Page(s): 152 - 160
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    A three-dimensional (3-D biomechanical model was used to determine upper extremity kinematics of 16 male subjects with low-level paraplegia while performing wheelchair propulsion (WCP). A six-camera VICON motion analysis system was used to acquire the coordinate data of ten anatomic markers. Joint axes for the wrist and elbow were defined along with the planes of motion for the upper arm (humerus) and trunk. The group's mean and standard deviation profiles were graphed for eight of the nine rotations measured during WCP. Variability in the intercycle and intersubject movement patterns were calculated using the root mean square standard deviation (RMSσ) and the coefficient of variation (CV). Motion pattern similarities were quantified using the coefficient of multiple correlation (CMC). The intercycle (Nc⩾6) motion patterns of individual subjects were highly consistent, similar, and repeatable during WCP. This was confirmed by low CVc values (3-31%), high CMCc values (0.724-0.996) and RMSσ c values below 3.2°. For the group, mean values of the propulsion velocity, cadence, and propulsion cycle duration were 89.7 m/min, 66.1 pushes/min, and 0.96 s, respectively. Humeral plane and rotation showed large excursions (76.1-81.6°), while trunk lean and forearm carrying angle displayed relatively small ranges of motion (5.5-10.9°). The intersubject N3=16) motion patterns were less similar compared to individual intercycle patterns. This was evidenced by higher CV3 values (12-128%) and lower CMC3 values (0.418-0.935). Intersubject humeral patterns were the most consistent while trunk lean was the least consistent. Intersubject root mean square standard deviations (RMSσ3) were more than three times the corresponding intercycle values for all nine rotations View full abstract»

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  • Development of transportable wheelchair design criteria using computer crash simulation

    Page(s): 171 - 181
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    The Americans with Disabilities Act (ADA) has led to an increase in disabled travelers, many of whom are unable to transfer to a vehicle seat and are required to use their wheelchair to fulfill this function. ANSI/RESNA is currently developing a transportable wheelchair standard which will identify design requirements and testing methods for wheelchairs suitable for transport. Wheelchair manufacturers should begin to modify their existing design criteria established for a normal mobility function to design criteria appropriate for a transportation function which may subject the wheelchair to large dynamic crash forces. A thorough understanding of the crash environment and its effect on the wheelchair is necessary to insure the safety of the wheelchair user. To assist manufacturers in the design effort, this study uses mathematical crash simulations to evaluate loads imposed upon a wheelchair when subjected to a 48 kph/20 g frontal crash. Using a four-point belt tiedown system to secure the wheelchair, securement point, seat, lap belt anchor, and wheel loads are evaluated under three different securement configurations. Results show that positioning of rear securement points near the wheelchair center of gravity can serve as an effective strategy for managing crash response and loadings on the wheelchair. Force ranges for each of the evaluated parameters, derived for a 50th percentile male using a simulated power wheelchair, are provided for use as a preliminary guide when designing transportable wheelchairs View full abstract»

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  • Preliminary test method for the determination of surface firmness [wheelchair propulsion]

    Page(s): 182 - 187
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    The Americans with Disabilities Act Accessibility Guidelines (ADAAG) specify that ground and floor surfaces should be firm, stable, and slip-resistant. These specifications are subjective; objective methods for assessing surface firmness and stability are lacking. Objective measures are needed to assess the accessibility of walking and wheeling surfaces and to improve accessibility for people with mobility limitations. This research study focused only on the development of an objective wheelchair work measurement method to assess surface firmness. Firmness was quantified in terms of the work per meter required to propel a wheelchair across the surface. Work was determined by using a SMARTwheel to measure the forces applied to the pushrim. This measurement method was evaluated on carpet, hard trail surfaces, and various playground surfacing materials. Measurements were also taken on an adjustable ramp set at different grades, cross slopes, and grade/cross slope combinations. Reliable results were obtained on all test surfaces except two (sand and pea gravel) which could not be negotiated by the test wheelchair rider according to the test protocol. The test method was capable of measuring a wide range of surface types, produced repeatable results on nearly all test surfaces, and was sensitive enough to measure 1% changes in grade and differences in surfacing materials. Comparisons between the measurements made on level surfaces and on various ramp angles demonstrated the feasibility of using the work per meter value for a specific ramp grade as pass/fail performance criteria for short distances of accessible surfaces. For outdoor recreational environments, this work measurement method would provide an objective measure of firmness which could be used to classify surfaces into categories (e.g., hard, firm, soft) View full abstract»

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  • Initial results in the development of a guidance system for a powered wheelchair

    Page(s): 143 - 151
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    Describes the development of an automatically guided powered wheelchair for individuals with severe disabilities. The navigation and control of the wheelchair is based the accurate estimation of the location of the wheelchair within its operating workspace. A novel method used to generate and track reference paths which take the user to and from various destinations within the wheelchair's environment is presented. The paper also provides a qualitative description of the restrictions and requirements that are specific to the wheelchair application as well as the way in which the current system addresses these restrictions and requirements. Finally, actual experimental runs of the wheelchair system are presented View full abstract»

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  • Estimating mechanical parameters of leg segments in individuals with and without physical disabilities

    Page(s): 201 - 211
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    Methods are described for estimating the inertia, viscosity, and stiffness of the lower leg around the knee and of the whole leg around the hip that are applicable even to persons with considerable spasticity. These involve: (1) a “pull” test in which the limb is slowly moved throughout its range of motion while measuring angles (with an electrogoniometer) and torques (with a hand-held dynamometer) to determine passive stiffness and (2) a “pendulum” test in which the limb is moved against gravity and then dropped, while again measuring angles and torques. By limiting the extent of the movement and choosing a direction (flexion or extension) that minimizes reflex responses, the mechanical parameters can be determined accurately and efficiently using computer programs. In the sample of subjects studied (nine with disability related to spinal cord injury, head injury, or stroke, and nine with no neurological disability), the inertia of the lower leg was significantly reduced in the subjects with disability (p<0.05) as a result of atrophy, but the stiffness and viscosity were within normal limits. The values of inertia were also compared with anthropometric data in the literature. The identification of these passive parameters is particularly important in designing systems for functional electrical stimulation of paralyzed muscles, but the methods may be widely applicable in rehabilitation medicine View full abstract»

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  • Projection of the point of force application onto a palmar plane of the hand during wheelchair propulsion

    Page(s): 133 - 142
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    The objective of this study was to develop and test a method for projecting the pushrim point of force application (PFA) onto a palmar plane model of the hand. Repetitive wheelchair use often leads to hand and wrist pain or injury. The manner by which the hands grasp the pushrim and how the forces and moments applied to the pushrim are directed may contribute to the high incidence of pain and injury. The projections of the PFA onto the palmar surface model of the hand reside primarily within zone II. These results are in agreement with previous studies which have assumed the PFA to be coincident with one of the metacarpophalangeal (MP) joints. However, the results from three subjects show different PFA patterns within the palmar surface of the hand which can be related to each subject's propulsion pattern, and the PFA is not focused at a single MP joint. Projection of the world coordinates of the four hand marker system onto the palmar plane show the resolution to be within 3 mm, or one half the diameter of the passive reflective markers. The errors in the planar model assumption were greatest for the second and fifth MP markers. This was expected because as the hand grasp changes these markers do not remain coplanar. The results of this study indicate that new knowledge about how forces are applied by the hand onto the pushrim can be obtained using this method. This technical note provides insight into understanding the details within the kinetics of wheelchair propulsion and describes a technique for estimation of the PFA on the palmar surface of the hand. This technical note provides initial results from three different wheelchair users View full abstract»

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  • The effect of wheelchair handrim tube diameter on propulsion efficiency and force application (tube diameter and efficiency in wheelchairs)

    Page(s): 123 - 132
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    To determine the optimum tube diameter of a standard handrim-propelled wheelchair, the effect of tube size and shape on physiological and kinetic parameters was studied. Six able-bodied male subjects performed two tests on a wheelchair ergometer. Tests were performed against work loads comparable to every day use and with two different handrim tube diameters, a handrim with an oval 25 by 30 mm diameter (LR) and one with an 18 mm diameter (SR). The large tube diameter (LR) yielded slightly but significantly lower values for the physiological parameters. Gross mechanical efficiency was on average 7% for the LR and 6.3% for the SR. No significant results were found for force application parameters related to the direction of the applied force or the torque by the hand onto the handrim surface. As technique parameters could not explain the higher mechanical efficiency (ME) when using the LR, it is suggested that hand grip constraints in the push phase (finger flexor activity) might be responsible. Another possible explanation is that with a better hand grip using LR, less stabilization by the larger muscle groups at the elbow and shoulder is needed. The measured technique parameters seem to be determined by geometric constraints of the arm and shoulder. The technique requirements resulting from the forced trajectory of the Propulsion movement are also likely to determine the technique parameters. Regarding the low mechanical efficiency of handrim propulsion, which is partly caused by the forced unfavorable trajectory of the hand, an alternative propulsion mechanism is suggested View full abstract»

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  • Determination of wheelchair dynamic load data for use with finite element analysis

    Page(s): 161 - 170
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    A methodology is introduced for the experimental determination of the dynamic loads which act on a wheelchair. A box frame wheelchair and a cantilever frame wheelchair were tested on an ANSI/RESNA curb-drop tester. The accelerations of an ANSI/RESNA test dummy were recorded with an array of 12 accelerometers mounted as four three-axis groups. Signal averaging was used to produce a composite dynamic load history. The dynamic loads were calculated from the acceleration data and the inertia of the test dummy using software written by the authors. These loads were imported into a finite element program (ALGOR) as load cases. A prototype carbon fiber design was then optimized through design and analysis iterations. The results of the acceleration data indicate that the curb-drop test produces an asymmetric loading scheme. One of the rear wheels hits the ground before the other, placing most of the dynamic load on one side of the wheelchair. The favored side appears to be fixed at the time of setup, preliminary results are given for the design of a modular carbon fiber wheelchair using the finite element (FE) method. These results indicate, however, that the use of a static factor of safety is, in most cases, inadequate for the dynamic loads present in the curb-drop test View full abstract»

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  • M3S: the local network for electric wheelchairs and rehabilitation equipment

    Page(s): 188 - 192
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    M3S is an open electric network standard for connecting rehabilitation equipment, especially electric modules in a wheelchair, it provides bidirectional communication at 250 kbaud via a CAN bus and extra safety lines for “Dead Man's Switch” and a TURN ON key. In an M3S system, the same input device may be used for controlling many different output devices in different operating modes. It provides flexible configuration tools for adapting the system for the individual user, M3S has been demonstrated and tested in more than ten different European development projects View full abstract»

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Aims & Scope

This Transaction ceased publication in 2000. The current retitled publication is IEEE Transactions on Neural Systems and Rehabiliation Engineering.

Full Aims & Scope