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Development of an Automated Wheelchair Tiedown and Occupant Restraint System

For this project funded by the National Highway Traffic Safety Administration, UMTRI researchers will build on previous wheelchair transportation safety efforts to develop an automated wheelchair tiedown and occupant restraint system (AWTORS) that could be used in automated vehicles where a driver is not available to help secure the wheelchair and occupant. Experts in restraint system design from ZF will be our partners.

For the wheelchair tiedown portion of the system that attaches the wheelchair to the vehicle, we will design hardware meeting the Universal Docking Interface Geometry (UDIG) specified in voluntary wheelchair safety standards WC18 and WC19. Similar in concept to the standardization of trailer hitches that allows any semi-tractor to attach and tow any trailer, UDIG has been proposed as a solution to allow any wheelchair user to dock in any vehicle if the hardware on each meets dimensional specifications. The wheelchair attachment hardware will consist of components attached to rear structures of the wheelchair below seat level.  The docking hardware will consist of a floor-mounted device with hooks; the user can deploy a mechanism with hand or voice control to engage the hooks with the wheelchair attachment hardware.

The primary element of the automated occupant restraint system will be a 3-point seat belt that can be placed on the occupant using a hand control to rotate the shoulder/lap anchor point into position. The system will incorporate advanced seatbelt features to improve belt fit for a variety of occupant sizes and optimize protection in a crash. In addition, different airbag designs will be explored to provide supplemental restraint for occupants whose seat height and width may vary.

The AWTORS prototypes will be developed using a combination of computational modeling, volunteer evaluation, and dynamic testing. To provide data for model validation, a surrogate wheelchair fixture equipped with UDIG securement hardware will be dynamically tested in front and side impact conditions using the sled equipped with docking hardware. Computational modeling will be used to optimize belt anchorage geometry to accommodate a range of wheelchair and occupant sizes, as well as airbags to provide protection in front and side loading conditions. A minivan shell equipped with wheelchair ramps will be adapted to include variations of the automatic belt system and the docking hardware; wheelchair users will be recruited to assess the usability of the docking station and belt system and the range of belt fit. After additional modeling to incorporate findings from the volunteer tests, the revised AWTORS design, including airbags, may be tested dynamically in front and side impact using midsize male ATDs and the surrogate wheelchair fixture. Additional testing may be performed using production wheelchairs equipped with UDIG-compliant attachment hardware and small female and mid-sized male ATDs.

for more information, please contact Dr. Kathleen D. Klinich kklinich@umich.edu