Tilak Dutta

Evaluation of the Kinect™ sensor for 3-D kinematic measurement in the workplace.

Recording posture and movement is important for determining risk of musculoskeletal injury in the workplace, but existing motion capture systems are not suited for field work. Estimates of the 3-D relative positions of four 0.10 m cubes from the Kinect were compared to estimates from a Vicon motion capture system to determine whether the hardware sensing components were sensitive enough to be used as a portable 3-D motion capture system for workplace ergonomic assessments. The root-mean-squared errors (SD) were 0.0065 m (0.0048 m), 0.0109 m (0.0059 m), 0.0057 m (0.0042 m) in the x, y and z directions (with x axis to the right, y axis away from the sensor and z axis upwards). These data were collected over a range of 1.0-3.0m from the device covering a field of view of 54.0 degrees horizontally and 39.1 degrees vertically. Requirements for software, hardware and subject preparation were also considered to determine the usability of the Kinect in the field.

Usability testing of multimodal feedback interface and simulated collision-avoidance power wheelchair for long-term-care home residents with cognitive impairments

Many older adults in long-term-care homes have complex physical and cognitive impairments and have difficulty propelling manual wheelchairs. Power wheelchair use is restricted owing to safety concerns. Power wheelchairs with collision-avoidance features are being developed to enable safe and independent mobility; however, a paucity of information exists on interface features to help users navigate away from obstacles. We developed a system combining an interface with auditory, visual, and haptic feedback and a simulated collision-avoidance power wheelchair. This device allowed the investigator to stop movement of the power wheelchair when users approached obstacles and to deliver feedback to help them navigate. Five long-term-care home residents with mild or moderate cognitive impairments evaluated device usability, which included effectiveness, efficiency, and user satisfaction. Each resident used the device for six 1 h sessions. Observations, feedback interviews, and outcome questionnaires were completed during and after the sessions. We found the device effective in enabling residents to achieve basic driving tasks and self-identified indoor mobility goals. Furthermore, residents perceived workload to be low and were satisfied with the device. Residents also felt that the feedback was useful to help them navigate away from obstacles.

A biomechanical assessment of floor and overhead lifts using one or two caregivers for patient transfers.

This study investigated the differences in peak external hand forces and external moments generated at the L5/S1 joint of the low back due to maneuvering loaded floor-based and overhead-mounted patient lifting devices using one and two caregivers. Hand forces and external moments at the L5/S1 joint were estimated from ground reaction forces and motion capture data. Caregivers gave ratings of perceived exertion as well as their opinions regarding overhead vs. floor lifts. Use of overhead lifts resulted in significantly lower back loads than floor lifts. Two caregivers working together with a floor lift did not reduce loads on the primary caregiver compared to the single-caregiver case. In contrast, two-caregiver operation of an overhead lift did result in reduced loads compared to the single-caregiver case. Therefore, overhead lifts should be used whenever possible to reduce the risk of back injury to caregivers. The use of two caregivers does not compensate for the poorer performance of floor lifts.

Design of built environments to accommodate mobility scooter users: Part II

Purpose. To determine the minimum dimensions needed to allow five models of powered mobility scooters to manoeuvre within five commonly encountered indoor spatial configurations. Method. We measured manoeuvrability of five scooters judged by their manufacturers to have a good combination of indoor mobility and outdoor performance (including in rural environments). We determined the minimum space needed to manoeuvre the scooters through the following five spatial configurations: turning 180° in a corridor, performing U-turns around 50 mm (2″) and 1200 mm (4′) obstacles, turning 90° from a doorway and approaching a counter or work surface from the side. Free-standing styrofoam walls were used to define each configuration. An expert driver repeatedly manoeuvred the scooters through each configuration while we incrementally decreased the dimension of interest until it was no longer possible to complete the manoeuvre. Each scooters turning diameter was also measured and compared to the manufacturers specification. Results. Minimum space requirements for each scooter for five spatial configurations are given and compared to existing standards. Conclusions. None of the scooters tested were capable of completing all manoeuvres within the space allowed by existing standards. These findings will contribute to recommendations for new standards for built environments that can accommodate scooter users.

High friction on ice provided by elastomeric fiber composites with textured surfaces

Two main applications requiring high friction on ice are automobile tires and footwear. The main motivation behind the use of soft rubbers in these applications is the relatively high friction force generated between a smooth rubber contacting smooth ice. Unfortunately, the friction force between rubber and ice is very low at temperatures near the melting point of ice and as a result we still experience automobile accidents and pedestrian slips and falls in the winter. Here, we report on a class of compliant fiber-composite materials with textured surfaces that provide outstanding coefficients of friction on wet ice. The fibrous composites consist of a hard glass-fiber phase reinforcing a compliant thermoplastic polyurethane matrix. The glass-fiber phase is textured such that it is aligned transversally and protruding out of the elastomer surface. Our analysis indicates that the exposed fiber phase exhibits a “micro-cleat” effect, allowing for it to fracture the ice and increase the interfacial contact area thereby requiring a high force to shear the interface.

Slip resistance of winter footwear on snow and ice measured using maximum achievable incline

Abstract Protective footwear is necessary for preventing injurious slips and falls in winter conditions. Valid methods for assessing footwear slip resistance on winter surfaces are needed in order to evaluate footwear and outsole designs. The purpose of this study was to utilise a method of testing winter footwear that was ecologically valid in terms of involving actual human testers walking on realistic winter surfaces to produce objective measures of slip resistance. During the experiment, eight participants tested six styles of footwear on wet ice, on dry ice, and on dry ice after walking over soft snow. Slip resistance was measured by determining the maximum incline angles participants were able to walk up and down in each footwear–surface combination. The results indicated that testing on a variety of surfaces is necessary for establishing winter footwear performance and that standard mechanical bench tests for footwear slip resistance do not adequately reflect actual performance. Practitioner Summary: Existing standardised methods for measuring footwear slip resistance lack validation on winter surfaces. By determining the maximum inclines participants could walk up and down slopes of wet ice, dry ice, and ice with snow, in a range of footwear, an ecologically valid test for measuring winter footwear performance was established.

The Evaluation of Vertical Pole Configuration and Location on Assisting the Sit-to-Stand Movement in Older Adults with Mobility Limitations

Grab-bars and transfer poles are common sit-to-stand aids for mobility limited older adults. This study investigated differences in kinetics and kinematics to characterize the lower-limb strength and dynamic balance requirements across different pole configurations and positions in nine mobility limited older adults. Poles were varied by location (near and far) and configuration (single vertical pole, double vertical poles, vertical pole with a horizontal bar). Results indicated that the far pole condition resulted in increased trunk (p < 0.001) and hip flexion (p < 0.01 and < 0.0001 for contralateral and ipsilateral sides, respectively), and a reduced peak vertical force applied to the pole (p < 0.001). Peak extension moments at the hip and knee were unchanged, and, therefore, pole position had no effect on task demands. Placing the pole unilaterally introduced a small kinetic asymmetry, which significantly increased peak knee extension moments on the ipsilateral side (p < 0.05). Finally, dynamic balance was relatively unchanged across pole conditions. These findings offer novel insight into pole use and the effect of varying pole location and configuration in a sample of older adults with mobility impairment, and provide the basis for future work.

Goal Attainment Scaling in Individuals with Upper Limb Spasticity Post Stroke

Focusing on rehabilitation goals is an effective approach for improving function in individuals with spasticity after stroke. The objectives of this study were to examine and map goals of post-stroke individuals with spasticity using the Goal Attainment Scale (GAS) and International Classification of Functioning, Disability and Health (ICF), and to evaluate the impact of botulinum toxin A (BoNTA) on occupational performance based on the type of rehabilitation goals. Thirty-one patients were recruited from an outpatient spasticity management clinic. Each patient set one goal, was injected with BoNTA in their spastic upper limb muscles and received standard rehabilitation services twice a week for four weeks. Twenty-seven participants achieved the expected level, and four exceeded the expected level of their rehabilitation goals. Fifty-five percent of the goals were related to Activity/Participation, and 45% of the goals were categorized in the Body Structures and Function domain of the ICF. Fifteen goals focused on positioning, while 16 goals focused on (independent) activities of daily living (ADL/IADL). Both the positioning and ADL/IADL groups experienced a reduction in MAS following the administration of BoNTA. The positioning group was older and more impaired. Mapping goals to ICF identifies specific targets for intervention, establishes a common language within the interdisciplinary team and contextualizes the ways disability impacts goals. This study is limited by a relatively small sample size and absence of a functional measure. Further studies can explore the development of goal/item banks to advance the use of GAS for spasticity management. Copyright

Improving Slip Resistance on Ice: Surface-Textured Composite Materials for Slip-Resistant Footwear

Falls present a massive health risk for older adults. Half of those over 80 will fall at least once a year with 1 in 5 suffering a serious injury. Footwear outsole material that provides good grip on ice and snow can potentially prevent many of these injuries. Our team has developed our own promising patent-pending composite outsole materials with a unique structure that consist of soft rubber compound with hard microscopic fibers protruding out from the surface. In this study, we attempt to optimize the ice friction performance of our composite for extended use. We investigate the effect of manufacturing and testing parameters using the Taguchi method for robust design. Our results on optimization of process parameters demonstrate that fiber content at 8% volume fraction with mold temperature sets at 120 °C lead to maximum ice friction properties before and after simulated wear. The optimized composite design showed a higher coefficient of friction (COF) on ice than any on the market now, which highlights the capability of the material to provide improved traction on icy surfaces and prevent fall-related injuries.

Assisting Frail Seniors With Toileting in a Home Bathroom: Approaches Used by Home Care Providers:

Home care providers experience high occupational injury rates. Improving safety is becoming increasingly urgent as this sector expands to support the aging population. Caregivers identify assisting with toileting as a particularly frequent and difficult activity. This mixed-methods observational study identified and analyzed the toileting subactivities that place care providers at the greatest risk of musculoskeletal injury. Eight personal support workers (home care aides) assisted a frail older adult (actor) in a simulated home bathroom. Overall technique and body postures were analyzed. Exposure to musculoskeletal injury risk factors (low back loads and time in extreme trunk postures) was greatest when removing/replacing clothing and providing posterior perineal care; high loads were also possible during transfers. Exposures can be reduced by lowering the pants only to knee level or squatting to raise them. A bidet seat or attachment can perform perineal cleaning, which accounted for 32% of time in severe trunk flexion.