Andrew J. Rentschler

Intelligent walkers for the elderly: performance and safety testing of VA-PAMAID robotic walker.

A walker that could help navigate and avoid collisions with obstacles could help reduce health costs and increase the quality of care and independence of thousands of people. This study evaluated the safety and performance of the Veterans Affairs Personal Adaptive Mobility Aid (VA-PAMAID). We performed engineering tests on the VA-PAMAID to determine safety factors, including stability, energy consumption, fatigue life, and sensor and control malfunctions. The VA-PAMAID traveled 10.9 km on a full charge and avoided obstacles while traveling at a speed of up to 1.2 m/s. No failures occurred during static stability, climatic, or fatigue testing. Some problems were encountered during obstacle climbing and sensor and control testing. The VA-PAMAID has good range, has adequate reaction time, and is structurally sound. Clinical trials are planned to compare the device to other low-technical adaptive mobility devices.

Evaluation of selected ultralight manual wheelchairs using ANSI/RESNA standards

OBJECTIVES To provide data for clinicians and wheelchair users to compare the durability, strength, stability, and cost effectiveness of four different ultralight wheelchair models, and to compare the results of this study with those published for lightweight wheelchairs. DESIGN Standards testing and cost-effectiveness analysis of four wheelchair models from different manufacturers (12 wheelchairs total). RESULTS There were significant differences (p< or =.05) in the fatigue life and value (equivalent cycles per dollar) among the ultralight wheelchairs tested. There was also a significant difference (p< or =.05) in rearward stability tilt angle for the least and most stable configurations. There were no differences in forward and lateral stability. The ultralight wheelchairs (1,009,108 cycles) had significantly (p< or =.05) higher fatigue lives than previously reported for lightweight wheelchairs (187,370 cycles). The lightweight wheelchairs had a mean value of 210 cycles per dollar compared to 673 cycles per dollar for the ultralight wheelchairs. The difference in value for the lightweight and ultralight wheelchairs was statistically significant (p< or =.05). CONCLUSION There were differences in the fatigue life and value among the four models of ultralight manual wheelchairs tested. This indicates that ultralight manual wheelchairs are not all of equal quality. The fatigue life and value of the ultralight manual wheelchairs were significantly higher than those previously reported for lightweight manual wheelchairs. This indicates that ultralight wheelchairs may be of higher quality than lightweight manual wheelchairs. Clinicians and consumers should seriously consider selecting an ultralight manual wheelchair to meet their wheelchair mobility needs.

Comparison of fatigue life for three types of manual wheelchairs

This study examines three different types (depot, lightweight, ultralight) of manual wheelchairs that have been tested to fatigue according to ISO standards. Results indicate that ultralight wheelchairs were significantly better than lightweight and depot with regard to fatigue life.

Fatigue-life of two manual wheelchair cross-brace designs

OBJECTIVE To compare the durability of two designs of cross-braces for folding manual wheelchairs and to determine the nature of wheelchair cross-brace failures. DESIGN Fatigue testing of two folding wheelchair cross-brace designs (one with a rectangular cross-section and the other with a circular cross-section). A total of 20 cross-brace pairs were tested. RESULTS The cross-braces with a circular cross-section endured a mean +/- SD of 100,159 +/- 45,814 cycles before experiencing a fatigue failure, whereas the cross-braces with a rectangular cross-section endured an average of 261,254 +/- 160,741 cycles. A t test showed significant differences (p = .01) in fatigue-life between cross-braces with a circular cross-section versus cross-braces with a rectangular cross-section. All 20 cross-braces experienced similar fatigue failures that would develop at the bolt hole where the two cross-braces connect to form a hinge. CONCLUSION The results suggest that the rectangular cross-brace design has a longer fatigue-life than the circular cross-brace design. People should regularly inspect the cross-brace for cracks. The area around the bolt forming the hinge should be inspected carefully. If a crack is observed, the cross-brace should be replaced immediately.

A comparison of the dynamic and static stability of power wheelchairs versus scooters

Currently, there are various different types of power wheelchairs and scooters available to consumers. Static and dynamic stability are two of the most important safety issues associated with powered mobility. This study determined the stability of 15 different power wheelchairs/scooters. Significant differences were found between the wheelchairs and scooters during both static and dynamic stability.

Displacement between seating surface and test dummy during transitions with a variable configuration wheelchair

Stand-up and reclining wheelchairs are important for providing pressure relief, blood flow, and function. This study examined the shear displacement between a test dummy and wheelchair seat. The results showed that shear displacement was present, but lower than previous reports.