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.