Evaluation of a manual wheelchair interface to computer games.

The sedentary lifestyle of many people with spinal cord injury (SCI) has lead to cardiovascular diseases being a major health concern. A suitable exercise program may help improve the SCI individual's cardiovascular fitness level. GAMEWheels is an interface between a custom wheelchair roller system and a computer that enables an individual to control computer video games by driving his or her wheelchair. The purpose of Phase 1 was to evaluate the design of the GAMEWheels system and to determine the type of computer video game that is likely to motivate wheelchair users to exercise. Phase 2 included physiologic testing of wheelchair users and the GAMEWheels system to investigate whether the system elicits an exercise training response. Thirty-five subjects were recruited to evaluate the GAMEWheels by playing three commercial computer games (Phase 1) and to identify the computer game that they would prefer to use when exercising. The feedback from Phase 1 was used with test subjects to verify that the GAMEWheels system elicits an exercise training effect (Phase 2). Phase 2 included 10 subjects using the GAMEWheels system to play Need for Speed II. During game play, physiologic data were collected and the subjects' oxygen consumption and heart rate were analyzed. Analysis showed that the GAMEWheels system induced nine subjects to reach their training zone, defined as 50% and 60% of their maximum oxygen consumption and heart rate, respectively. This study demonstrates that the GAMEWheels system elicits an exercise training response.

Kinematic comparison of Hybrid II test dummy to wheelchair user.

Hybrid test dummies provide a safe alternative to human subjects when investigating mechanisms of wheelchair tips and falls. The data that researchers acquire from these test dummies are more useful if the test dummy represents the population being studied. The goal of this study was to measure the validity of a 50th percentile Hybrid II test dummy (HTD) as an accurate representation of a wheelchair user. A test pilot with T8 paraplegia due to traumatic spinal cord injury served as a basis for validation. Simple modifications were made to the HTD to approximate the trunk stability characteristics of a person with a spinal cord injury. An HTD, a modified HTD, and a human test pilot were seated in an electric-powered wheelchair and several braking tests performed. The standard HTD underestimated the kinematics when compared to the test pilot. The modified HTD had less trunk stability than the standard HTD during all braking methods. The modified HTD and wheelchair test pilot had similar trunk stability characteristics during kill switch and joystick full-reverse braking conditions. The modified HTD is a satisfactory representation of a wheelchair user with a spinal cord injury; however, the modified test dummy underestimates the trunk dynamics during the less extreme joystick release braking. Work should continue on the development of a low-speed, low-impact test dummy that emulates the wheelchair user population.

Displacement between the seating surface and hybrid test dummy during transitions with a variable configuration wheelchair: a technical note.

Changing seating posture can extend the amount of time a person can safely remain seated without damaging tissue or becoming fatigued. The Excelsior is an electrically powered wheelchair that utilizes sit-to-stand (STS) and sit-to-recline (STR) motions to aid in pressure relief. The motion of the wheelchair seating system must closely follow anatomical paths or ulcers may develop from the resulting shear forces. Displacement between the person and the wheelchair seating surface is one measure of these shear forces. The displacement between a Hybrid II 50th percentile anthropometric test dummy (ATD) and the seating surface of the Excelsior wheelchair was examined during STS and STR with two cushions, a Jay Active and a low-profile Roho cushion. The difference between the backrest and ATD back angles were 4.29 degrees +/- 2.13 degrees and 1.78 degrees +/- 1.73 degrees for the Roho and Jay cushions respectively during STS and 3.32 degrees +/- 4.21 degrees and 10.71 degrees +/- 6.20 degrees during STR. These were statistically significant at p<.05. During STS, shear displacement between the Hybrid II back and Excelsior backrest did not exceed 1.5 cm for either cushion. ATD thigh-to-seat displacements were 2.5 cm for the Jay and 3.0 cm for the Roho cushion. STR produced dummy thigh-to-seat displacements of 1.5 cm and 3.5 cm for the Jay and Roho cushions respectively. Shear displacement in the ATD back was about 3.5 cm for the Roho and 6 cm for the Jay. The latter displacement should be reduced; however, the other conditions are marginal or acceptable. Hysteresis was acceptable or better for all cushion/motion combinations, with the highest net displacement of about 2.5 cm.

Braking electric-powered wheelchairs: effect of braking method, seatbelt, and legrests.

OBJECTIVE: To examine the influence of three electric-powered wheelchair braking conditions and four wheelchair seating conditions on electric-powered wheelchair motion and Hybrid II test dummy motion. This study provides quantitative information related to assessing the safety of electric-powered wheelchair driving. DESIGN: Rehabilitation engineering comparison and ANSI/ RESNA standards testing. Convenience sample of eight different electric-powered wheelchairs. Within-chair comparisons were conducted. INTERVENTION: Electric-powered wheelchairs were compared under three braking scenarios (joystick release, joystick reverse, power-off) and four seating conditions (seatbelt and legrests, seatbelt and no legrests, no seatbelt but legrests, no seatbelt and no legrests). SETTING: A rehabilitation engineering center. MAIN OUTCOME MEASURES: The braking distance, braking time, and braking accelerations for electric-powered wheelchairs during three braking scenarios; trunk motion, head motion, and trunk angular acceleration during three braking scenarios and four seating conditions; and number of falls from the wheelchairs for three braking scenarios and four seating conditions. RESULTS: Significant differences (p < .05) were found in braking distance, braking time, and braking acceleration when comparing the joystick release and joystick reverse scenarios with the power-off scenario. The mean braking distance was shortest with the power-off braking scenario (.89m), whereas it was longest when the joystick was released (1.66m). Significant differences (p < .05) in head displacement and trunk angular displacement were observed among braking conditions and between seating conditions. There were also significant differences (p = .0011) among braking conditions for maximum trunk angular acceleration. The Hybrid II test dummy fell from the wheelchairs with highest frequency when there were no legrests and no seatbelt used. CONCLUSION: The results of this study indicate that use of a seatbelt when driving an electric-powered wheelchair reduces the risk of falling from a wheelchair. Furthermore, the use of legrests can reduce the risk of injury to the wheelchair driver. This study shows that the most abrupt braking occurs when deactivating the power switch.