Effect of interpolation on parameters extracted from seating interface pressure arrays

Wininger, Michael; Crane, Barbara

doi:10.1682/jrrd.2014.04.0101

Cited by 8 publications

(3 citation statements)

References 43 publications

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“…Previously, recline values were reported as the angle between the seat and backrest. In keeping with current clinical practice, recline values in this paper were modified to denote the sagittal angle of the backrest from the vertical (Waugh & Crane, 2013). That is to say, the previously reported recline angle of 100° and 120° were updated to 10° and 30°, respectively, although the actual recline configurations were not changed.…”

Section: Instrumentationmentioning

confidence: 99%

Dynamic changes in seating pressure gradient in wheelchair users with spinal cord injury

Lung

Yang

Liau

et al. 2019

Assistive Technology

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Pressure ulcer interventions are commonly assessed with measures of seating interface pressure, such as peak pressure gradients (PPGs). Decreases in PPG magnitudes may reduce pressure ulcer risk by decreasing tissue deformation and increasing tissue perfusion of at-risk weight-bearing tissues. Changes in PPG directions, which have previously been overlooked in the seating pressure literature, may provide a transient increase in blood flow to at-risk tissues, even if the PPG magnitude and location remain the same. The purpose of this study was to assess both PPG components in response to combinations of wheelchair tilt and recline angles. Thirteen power wheelchair users were recruited into the study. Six combinations of wheelchair tilt (15°, 25°, and 35°) and recline (10° and 30°) were tested in random order. Each combination was tested with 5min upright sitting, 5-min tilt and recline, and 5-min maximal pressure relief recovery. Changes in PPG magnitudes and PPG directions under the left ischial tuberosity were computed for the six angle combinations. The findings in this study suggested that when combining wheelchair tilt and recline, the recline function may be particularly useful in reducing PPG magnitudes, while the tilt function may be particularly useful in manipulating PPG directions.

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Section: Instrumentationmentioning

confidence: 99%

Dynamic changes in seating pressure gradient in wheelchair users with spinal cord injury

Lung

Yang

Liau

et al. 2019

Assistive Technology

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“…[22,26,32,33] This has led to a spectrum of models, including linear. [34] , curvilinear. [35,36] , and cubic.…”

Section: Introductionmentioning

confidence: 99%

Surface‐Level Muscle Deformation as a Correlate for Joint Torque

Alvarez,

de Marcillac,

Jin

et al. 2024

Adv Materials Technologies

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Wearable technology excels in estimating kinematic and physiological data, but estimating biological torques remains an open challenge. Deformation of the skin above contracting muscles—surface‐level muscle deformation—has emerged as a promising signal for joint torque estimation. However, a lack of ground‐truth measures of surface‐level muscle deformation has complicated the evaluation of wearable sensors designed to measure surface‐level muscle deformation. A non‐contact methodology is proposed for ground‐truth measurement of surface‐level muscle deformation using a 2D laser profilometer. It shows how three metrics of surface‐level muscle deformation—peak radial displacement: r = 0.94 ± 0.05, surface curvature: r = 0.78 ± 0.10, surface strain: r = 0.83 ± 0.12—correlate strongly to changes in volitional elbow torque, further exploring the impact of measurement location or joint angle on these relationships. A nonlinear, lead‐lag relationship between surface‐level muscle deformation and torque is also found. The findings suggest that surface‐level muscle deformation is a promising signal for non‐invasive, real‐time estimates of torque. By standardizing measurement, the methodology can help inform the design of future wearable sensors.

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“…Thus, current clinical interventions and research methods are primarily based on pressure magnitude features. Work has been ongoing to determine reliable variables [51] and parameters [35,56] for analyzing interface pressure magnitudes. Meanwhile, pressure ulcer incidence and prevalence remain excessive.…”

Section: Introductionmentioning

confidence: 99%

Nonnegative matrix factorization for the identification of pressure ulcer risks from seating interface pressures in people with spinal cord injury

Yang

Jan

2019

Med Biol Eng Comput

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The purpose of this study was to predict and visualize pressure ulcer risks by using a novel approach of extracting computational features from seating interface pressures in people with spinal cord injury (SCI). In conventional clinical practice, seating interface pressure assessments rely on descriptive statistics of pressure magnitude. In this study, rank-2 nonnegative matrix factorization (NMF) was applied to the seating interface pressure maps during loading and pressure-relieving conditions in 16 people with SCI. The NMF basis images were used for visual interpretation and computational prediction of pressure ulcer risks. The two NMF basis images encapsulated pressure concentration and pressure dispersion, respectively. The first basis converged on the ischial tuberosity under both seating conditions, whereas the second basis converged anterior to the ischial tuberosity during loading and converged on the coccyx during unloading. The classification yielded 81.25% overall accuracy. In general, higher ulceration risk was associated with higher and lower activations of the first and second bases, respectively. The NMF pipeline yielded promising performance. Basis visualization affirmed the importance of lower ischial pressure and higher distribution dispersion while also revealing that clinical practice may currently be underestimating the importance of coccygeal pressure in response to pressure relieving activities.

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Effect of interpolation on parameters extracted from seating interface pressure arrays

Cited by 8 publications

References 43 publications

Dynamic changes in seating pressure gradient in wheelchair users with spinal cord injury

Dynamic changes in seating pressure gradient in wheelchair users with spinal cord injury

Surface‐Level Muscle Deformation as a Correlate for Joint Torque

Nonnegative matrix factorization for the identification of pressure ulcer risks from seating interface pressures in people with spinal cord injury

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