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Rehabilitation Engineering and Applied Research Lab (REAR Lab)

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Publication Search Results

Now showing 1 - 10 of 23
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    Dataset for "Investigating shock and vibration exposure of a manual wheelchair during multi-drum testing"
    (Georgia Institute of Technology, 2023-09-21) Misch, Jacob ; Sprigle, Stephen
    Wheelchair users are highly susceptible to injury and immobility in the event of a wheelchair breakdown. Durability, or fatigue life, of manual wheelchair frames is currently evaluated using a standardized multi-drum test, which provides frequent impacts to the casters and rear wheels of the wheelchair. Not much is known about the underlying mechanics of the test, making it difficult to properly assess how appropriate this test is as a predictor of wheelchair frame longevity during real-world usage. This study aimed to investigate the applicability of the multi-drum test as an accelerated durability test by comparing breakdown statistics, vibrations, and shocks between the test and real-world usage. Triaxial accelerometers were used to measure the shocks and vibrations transmitted through an ultralightweight manual wheelchair frame during a portion of the multi-drum test. Occupant mass was varied (80 kg, 125 kg) to reflect standard user weight and maximum weight capacity of the chair. Root-mean-square acceleration and vibration dose values were greatest along the vertical axis, and overall similar for both occupant masses. Comparisons with existing literature suggest that the shocks and vibrations experienced within the multi-drum test far exceed values seen in real-world wheelchair usage. Similarly, frame-based fatigue failures are more common during the multi-drum test. These results suggest that the current test protocol is not well-suited to be an accelerated durability test for manual wheelchairs.
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    Dataset for "Comparison of Propulsion Costs and Vibrations Across Carbon Fiber and Aluminum Rigid Manual Wheelchairs"
    (Georgia Institute of Technology, 2023-09-20) Misch, Jacob ; Allen, Taylor ; Suarez, Alicia ; Sprigle, Stephen
    Propulsion efficiency and vibration exposure are two primary concerns when configuring a manual wheelchair. Recent manufacturing techniques have focused on using lightweight materials like carbon fiber to reduce energy expenditure during propulsion and improve vibration attenuation compared to aluminum or steel frames. This study utilized a robotic wheelchair propulsion device to measure the propulsion cost, vibration exposure at the seat, and vibration transmissibility through the frame during travel over smooth (tile) and textured (brick) surfaces for four rigid ultra-lightweight manual wheelchairs made of carbon fiber (N=1) and aluminum (N=3). Component selection (wheels, tires, casters, cushion) and the robotic occupant parameters (weight, fore-aft weight distribution, propulsion characteristics) were standardized across all four frames. Results show no meaningful differences between the carbon fiber and aluminum frames in any of the three variables (i.e., 95% CI does not fully exceed ±5% for propulsion cost or ±6% for vibration and transmissibility). These findings imply that other frame design features are more impactful to vibrations and propulsion efficiency than the material selection. Minimizing wheelchair vibration exposure and maximizing propulsion efficiency are more easily achieved through considerate selection of components, especially cushions and tires, respectively.
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    Wheelchair in-seat monitoring design considerations
    (Georgia Institute of Technology, 2022-10) Sprigle, Stephen ; Sonenblum, Sharon Eve ; Deshpande, Yogesh ; Jordan, Kathleen
    Wheelchair in-seat activity trackers are developed to monitor and provide feedback about the pressure redistributing movements of wheelchair users, including weight shifts and other postural shifts that redistribute buttocks pressures. From a design perspective, in-seat activity trackers reflect myriad design decisions that impact performance, function, and usability. Many, if not all, of these decisions involve interconnections across system components, and can have significant impact on tracker operation and user-experience. Technology developers will have to manage many benefits and trade-offs that accompany design of each subsystem. Two documents were created based upon real-world use of in-seat trackers to briefly identify design criteria and constraints that should be considered.
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    Dataset: Procedure to categorize wheelchair cushion performance using compliant buttock models
    (Georgia Institute of Technology, 2022-09) Sprigle, Stephen ; Deshpande, Yogesh
    Wheelchair cushion prescription often seeks to address tissue integrity in addition to other clinical indicators. Because hundreds of wheelchair cushion models are available, a benefit would result if cushions were classified in a more valid manner to help guide selection by clinicians and users. The objective of this research was to develop an approach to evaluate and classify wheelchair cushion performance with respect to pressure redistribution.
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    Procedure to categorize wheelchair cushion performance using compliant buttock models
    (Georgia Institute of Technology, 2022-09) Sprigle, Stephen ; Deshpande, Yogesh
    Purpose: Wheelchair cushion prescription often seeks to address tissue integrity in addition to other clinical indicators. Because hundreds of wheelchair cushion models are available, a benefit would result if cushions were classified in a more valid manner to help guide selection by clinicians and users. The objective of this research was to develop an approach to evaluate and classify wheelchair cushion performance with respect to pressure redistribution. Materials and methods: Two anatomically-based buttock models were designed consisting of an elastomeric shell that models overall buttock form and a rigid substructure that abstracts load-bearing aspects of the skeleton. Model shapes were based upon elliptical and trigonometric equations, respectively. Two performance parameters were defined, pressure magnitude and pressure redistribution. The pressure magnitude parameter compared internal pressure values of the test cushion to a flat foam reference material, resulting in three classifications, superior, comparable, and inferior. Surface sensors were used to distinguish cushions with high, moderate or low pressure redistribution performance. Ten wheelchair cushions were evaluated by both models using two loads that represent a range of body weights expected for 41–43 cm wide cushions. Results and Conclusion: A classification matrix is proposed using both models and performance parameters. Two cushions met criteria for the highest level of performance, and one cushion was deemed to have inadequate performance for therapeutic value. The proposed method has a sensitivity to discern differences, compatibility with different sized cushions, and a versatility in classification. As such, it stands as an improvement over existing classification approaches.
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    Dataset for "Effect of wheels, casters and forks on vibration attenuation and propulsion cost of manual wheelchairs"
    (Georgia Institute of Technology, 2022-08-10) Misch, Jacob ; Liu, Yuanning ; Sprigle, Stephen
    Manual wheelchair users are exposed to whole-body vibrations as a direct result of using their wheelchair. Wheels, tires, and caster forks have been developed to reduce or attenuate the vibration that transmits through the frame and reaches the user. Five of these components with energy-absorbing characteristics were compared to standard pneumatic drive wheels and casters. This study used a robotic wheelchair propulsion system to repeatedly drive an ultra-lightweight wheelchair over four common indoor and outdoor surfaces: linoleum tile, decorative brick, poured concrete sidewalk, and expanded aluminum grates. Data from the propulsion system and a seat-mounted accelerometer were used to evaluate the energetic efficiency and vibration exposure of each configuration. Equivalence test results identified meaningful differences in both propulsion cost and seat vibration. LoopWheels and SoftWheels both increased propulsion costs by 12-16% over the default configuration without reducing vibration at the seat. Frog Legs suspension caster forks increased vibration exposure by 16-97% across all four surfaces. Softroll casters reduced vibration by 11% over metal grates. Wide pneumatic 'mountain' tires showed no difference from the default configuration. All vibration measurements were within acceptable ranges compared to health guidance standards. Out of the component options, softroll casters show the most promising results for ease of efficiency and effectiveness at reducing vibrations through the wheelchair frame and seat cushion. These results suggest some components with built-in suspension systems are ineffective at reducing vibration exposure beyond standard components, and often introduce mechanical inefficiencies that the user would have to overcome with every propulsion stroke.
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    The Design of a Family of Parametric Anatomically-Based Compliant Buttock Models to Evaluate Wheelchair Cushion Performance - Fabrication Package
    (Georgia Institute of Technology, 2022-07) Deshpande, Yogesh ; Sprigle, Stephen
    The evaluation of wheelchair cushion performance is of interest to a variety of stakeholders. Over the years, several buttocks models have been used to evaluate wheelchair cushion performance. These vary in design and purpose, and can be generally classified as either rigid or compliant. To date, published studies using buttock models have been limited to using a single size model. Thus, they were designed to evaluate one size of cushions. A need exists to define a series of models that can be used to evaluate cushions of varying sizes. The objective of this project was to develop a family of compliant buttock models that are based upon the anatomical parameters of persons with varying body sizes. This paper will detail the designs, describe the anatomical basis for the design and provide the rationale for the design decisions. Supplemental material includes greater detail; the full CAD files and model fabrication instructions are available in an open access repository for persons who wish to fabricate the models.
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    Dataset for "Propulsion cost changes of ultra-lightweight manual wheelchairs after one year of simulated use"
    (Georgia Institute of Technology, 2022) Misch, Jacob ; Sprigle, Stephen
    Manual wheelchairs are available with folding or rigid frames to meet the preferences and needs of individual users. Folding styles are commonly regarded as more portable and storable, whereas rigid frames are commonly regarded as more efficient for frequent daily use. To date, there are no studies directly comparing the performances of the frame types. Furthermore, while differences have been reported in the longevity of the frame types, no efforts have been made to relate this durability back to real-world performance of the frames. This study investigated the propulsion efficiencies of 4 folding and 2 rigid ultra-lightweight frames equipped with identical drive tires and casters. A robotic wheelchair tester was used to measure the propulsion costs of each chair over 2 surfaces: concrete and carpet. A motorized carousel was used to drive the chairs 511 km around a circular track to simulate one year of use for each wheelchair. After simulated use, 5 of the 6 wheelchairs showed no decrease in propulsion effort, indicating that the frames were able to withstand the stresses of simulated use without detrimental impact on performance. In the unused 'new' condition, rigid chairs were found to have superior (>5%) performance over folding frames on concrete and carpet, and in the 'worn' condition rigid chairs had superior performance over folding chairs on concrete, but were comparable on the carpeted surface.
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    An Exploratory Analysis of The Role of Adipose Characteristics in Fulltime Wheelchair Users’ Pressure Injury History - Supplementary Data
    (Georgia Institute of Technology, 2021) Sonenblum, Sharon Eve ; Measel, Megan ; Sprigle, Stephen ; Greenhalgh, John ; Cathcart, John McKay
    The goals of this study were 1) to identify the relationship between adipose (subcutaneous and intramuscular) characteristics and pressure injury (PrI) history in wheelchair users, and 2) to identify subject characteristics, including Biomechanical Risk, that are related to adipose characteristics. Data in the supplement is associated with 43 full-time wheelchair users with and without a history of pelvic pressure injuries. Their buttocks were scanned in a seated posture in a FONAR UPRIGHT® MRI. Intramuscular adipose (the relative difference in intensity between adipose and gluteus maximus) and the subcutaneous adipose characteristics (the relative difference in intensity between subcutaneous adipose under and surrounding the ischium) were compared to pressure injury history and subject characteristics. Participants with a history of PrIs had different subcutaneous fat (subQF) characteristics than participants without a history of PrIs. Specifically, they had significantly darker adipose under the ischium than surrounding the ischium than participants without a history of PrIs. On the other hand, only when individuals with complete fat infiltration (n=7) were excluded, did individuals with PrI history have more fat infiltration than those without a PrI history. Presence of spasms and fewer years using a wheelchair were associated with leaner muscle. The results of the study suggest the hypothesis that changes in adipose tissue under the ischial tuberosity (presenting as darker SubQF) are associated with increased biomechanical risk for pressure injury. Further investigation of this hypothesis, as well as the role of intramuscular fat infiltration in PrI development may help our understanding of PrI aetiology. It may also lead to clinically-useful diagnostic techniques that can identify changes in adipose and biomechanical risk to inform early preventative interventions.
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    Friction characteristics of preventative wound dressings under clinically‐relevant conditions dataset
    (Georgia Institute of Technology, 2020-12-15) Sprigle, Stephen ; Caminiti, Riley ; Varenberg, Michael
    Wound dressings can be used prophylactically or during actual treatment. Preventative dressings have become a standard of care to prevent pressure ulcers in patients while in bed. While the mechanism of the preventative benefit has not been completely explained, the friction between the dressing and linen is hypothesized as being a key performance factor. The objective of this project was to quantify the static and kinetic coefficients of friction (COF) of various brands of prophylactic dressings under the stresses experienced in situ, while the dressings are in contact with bed linen materials. The COF of six commercial dressings were calculated using tribometer measurements. The ranges of static COF were 0.333-0.542 and kinetic COF were 0.333-0.513. Four dressings exhibited COF that were consistent with skin-linen values reported in the literature and all dressing COF appear to be lower than the COF of moist skin against linen.