Comfortable leg splay of mid-sized males in automotive seats.

Many factors affect the comfort of automotive seats including pressure distribution, vibration, temperature, and backrest inclination. However, one aspect of seating that has not been well studied is leg splay; splay is a rotation at the hips which causes the knees to move outward. The work presented here identified the ranges of "comfortable" splay in different styles of seats and related changes in seating pressure due to leg splay. Sixteen midsized male participants were tested in six seats: a flat control, three mid-sized sedan, a sports car, and a pickup truck. Participants sat with two leg conditions: 1) shoulder width apart and 2) rotating their legs to splay to a self-identified, comfortable position. For each test, the participant placed his left leg on a foot support and right leg on a depressible pedal to mimic a driving position. In each posture, leg angle and seat pan pressures were collected. Of the seats tested, the flat wooden seat had the highest possible splay (24.5°). The three sedan seats had similar splay angles (16.1-18.5°). The lowest splay values were in the sports car seat (8.96°) and truck seat (7.46°). This reduction in splay was attributed to the more aggressive bolsters in the sports car and a higher seat design position in the pickup truck seat. Following participant splay the pressures in the seat bolsters increased while the pressure in the left thigh and left buttocks regions decreased. By determining the comfortable ranges of splay and how pressure distribution is affected, seat designers and automobile manufacturers can use these data when evaluating seat designs and occupant positioning.

Mapping Together Kinetic and Kinematic Abilities of the Hand.

Millions of people have reduced hand function; this loss of function can be due to injury, disease, or aging. Loss of hand function is identified as reduced motion abilities in the fingers or a decrease in the ability of the fingers to generate force. Unfortunately, there are limited data available regarding each finger's ability to produce force and how those force characteristics vary with changes in finger posture. To relate motion and force abilities of the fingers, first, an approach to measure and map them together is needed. The goal of this work was to develop and demonstrate a method to quantify the force abilities of the fingers and map these forces to the kinematic space associated with each finger. Using motion capture and multiaxis load cells, finger forces were quantified at different positions over their ranges of motion. These two sets of data were then converted to the same coordinate space and mapped together. Further, the data were normalized for the index finger and mapped as a population space model. The ability to quantify motion and force data for each finger and map them together will provide an improved understanding of the effects of treatments and rehabilitation, identifying functional loss due to injury or disease, and device design.

A Potential Tool for the Study of Venous Ulcers: Blood Flow Responses to Load.

Venous ulcers are deep wounds that are located predominantly on the lower leg. They are prone to infection and once healed have a high probability of recurrence. Currently, there are no effective measures to predict and prevent venous ulcers from formation. Hence, the goal of this work was to develop a Windkessel-based model that can be used to identify hemodynamic parameters that change between healthy individuals and those with wounds. Once identified, these parameters have the potential to be used as indicators of when internal conditions change, putting the patient at higher risk for wound formation. In order to achieve this goal, blood flow responses in lower legs were measured experimentally by a laser Doppler perfusion monitor (LDPM) and simulated with a modeling approach. A circuit model was developed on the basis of the Windkessel theory. The hemodynamic parameters were extracted for three groups: legs with ulcers ("wounded"), legs without ulcers but from ulcer patients ("nonwounded"), and legs without vascular disease ("healthy"). The model was executed by two independent operators, and both operators reported significant differences between wounded and healthy legs in localized vascular resistance and compliance. The model successfully replicated the experimental blood flow profile. The global and local vascular resistances and compliance parameters rendered quantifiable differences between a population with venous ulcers and healthy individuals. This work supports that the Windkessel modeling approach has the potential to determine patient specific parameters that can be used to identify when conditions change making venous ulcer formation more likely.