Approximately 3.6 million people in the US use wheelchairs, but they cannot currently use them on aircraft, preventing many from flying. Among those that transfer to airline seating, many report instances of their wheelchairs being damaged during transport, as well as discomfort, injury, and social stigma experienced while transferring to an aircraft seat. A recent National Academy of Sciences (NAS) consensus document determined that it should be feasible on most commercial aircraft to allow passengers to use their wheelchairs. However, wheelchairs would need to meet the FAA crashworthiness requirements for current aircraft seats. These consist of dynamic tests simulating frontal and vertical loading, plus static pull tests. While voluntary, RESNA WC19 currently has standards for assessing frontal crashworthiness of wheelchairs used as seating in motor-vehicles. We hypothesize that wheelchairs meeting current RESNA standards for vehicles can meet the FAA crashworthiness requirements for airline seats. To test this hypothesis, we will construct adapted versions of the FAA test fixtures and test wheelchairs that meet current WC19 requirements under frontal, vertical, and static testing conditions. If needed, we would perform additional testing of wheelchairs with modifications made to improve their performance under FAA test conditions. We will also draft procedures that would adapt FAA seat testing standards so they can be used to evaluate wheelchairs.
The advent of automated vehicles (AVs) means that vehicle manufacturers have the opportunity to integrate wheelchair seating stations from the beginning of the design process. For ethical and liability reasons, manufacturers want to provide an equitable level of safety for all passengers, including occupants seated in wheelchairs. Because wheelchair geometries vary more than a single vehicle seat geometry, design of airbags and seatbelts for occupants seated in wheelchairs is challenging. This study, sponsored by the National Institute for Disability, Independent Living, and Rehabilitation Research (NIDILRR), will develop a set of physical and digital tools that can represent the diversity of wheelchair 3D geometries, which will help manufacturers design vehicles with better accommodation and safety for wheelchair-seated occupants. Research tasks will include 1) Development of test fixtures representing large and small wheelchairs for use in dynamic physical testing of occupant protection systems. 2) Formation of a virtual wheelchair fleet to facilitate geometric design of wheelchair seating stations. 3) Creation of computational models representing wheelchair test fixtures and a fleet of production wheelchairs to allow virtual design of occupant protection systems, and use such models to evaluate the benefit of additional test fixtures on safety improvement for wheelchair-seated occupants.
The goal of this project is to develop test procedures that will lead to improved safety in side impact crashes for people who travel while seated in their wheelchairs. Elements that are needed to achieve this are:
Wheelchairs that remains intact and keep the occupant positioned relative to the airbag
Tiedowns that secure wheelchairs under lateral loading
Occupant protection systems for nearside and farside impact
The test procedures, tools, and models developed in this project will need to address the different needs of wheelchairs manufacturers, WTORS manufacturers, and vehicle manufacturers, while also considering how to maximize both independence and safety of wheelchair users. The project will develop finite element (FE) models of tools, fixtures, and commercial products as part of the process to develop test procedures.
Transportation for people with mobility impairments who use wheelchairs depends on vehicle environments that accommodate their needs for safe and easy-to-use vehicle spaces. This project developed design guidelines on how to make passenger vehicles, and particularly autonomous vehicles, accessible for people in wheelchairs. The vehicle aspects addressed include doorways, ramps, lifts, handholds, interior access routes, wheelchair spaces, wheelchair securement, occupant protection for people in wheelchairs, floor surfaces, and operable parts. The recommendations were derived from the literature and precedents set by the Americans with Disabilities Act (ADA), where applicable. In the areas of ramp strength and wheelchair positioning, where no clear precedents exist, the project team developed relevant procedures that are documented in the Appendices. This document can be used to evaluate vehicle accessibility using the “good/better/best” categories established for each topic. These guidelines promote vehicle designs that can allow more people in wheelchairs to travel more independently, more safely, and more easily.
The volunteer study described in a separate report was conducted to assess whether the better and best recommendations provided improved accessibility and comfort compared to the good recommendations. Testing results generally did not show significant differences between conditions, which may be due to small sample size and limitations from the combinations of factor available on the test vehicles. However, participant feedback and data on belt fit provide useful information for accessible vehicle design.
For the initial phase of the Inclusive Design Challenge, we partnered with May Mobility to demonstrate the feasibility of using a UDIG-compatible docking system (coupled with an automated belt-donning system) in an electric Ford Transit modified for use by wheelchair users. Installing equipment in this vehicle allowed us to address many of the challenges that will occur in AV shuttles and other future vehicles. These challenges include installing vehicle anchorages and a wheelchair ramp in a vehicle where an array of batteries is located under the floor where these components usually would be attached or stored. It also allowed further study of the space required for a wheelchair user to maneuver into the docking station, and how the wheelchair seating station can be placed to optimize accessibility as well as space for other passengers in a van-sized shuttle.
This project developed an automated WTORS (AWTORS) that could be safely and independently used in an AV by someone using a wheelchair as vehicle seating (Klinich et al. 2021, under review). The project used past research, computational modeling, prototype construction, volunteer evaluation, and dynamic testing to demonstrate feasibility.
Computational modeling was used to optimize placement of the wheelchair station, locate the wheelchair anchorages relative to the occupant, optimize belt anchor locations, and determine airbag characteristics for front and side impacts. Frontal simulations showed improved injury measures with a SCaRAB airbag, particularly with suboptimal belt geometry. Side impact simulations showed adequate protection in nearside crashes with standard curtain airbags and outboard shoulder belt location. However, changes to belt geometry were insufficient to keep the occupant within the wheelchair during farside impacts, leading to design of a Center Airbag To Contain Humans (CATCH). Computer models of power and manual wheelchairs were developed and used to choose restraint and geometry parameters for sled testing.
The concept for securing the wheelchair to the vehicle used hardware meeting specifications of the UDIG that have been included in RESNA and ISO standards. Vehicle anchorages meeting the specifications were constructed, as were attachment designs for a commercial manual and power wheelchair. The occupant restraint portion of the AWTORS include an automatic seatbelt donning mechanism based on a past UMTRI prototype, but with geometric improvements.
Volunteer testing was performed with eight wheelchair users. Using the two study wheelchairs equipped with UDIG anchors, the study evaluated the usability of four wheelchair seating stations with different geometries, each with two different belt conditions. Data included videos of ingress and egress, scans of volunteer posture, and questionnaires to document the time spent docking the wheelchair and donning the seatbelt, belt fit, comfort, and potential usability issues. Average time for entry, docking, and donning was less than 2 minutes in all conditions. For three-quarters of trials, participants would recommend use of the docking and donning systems. The preparation of test fixtures for volunteer testing identified challenges in implementing optimal geometry defined through simulations.
Ten frontal sled tests were performed to demonstrate differences with belt geometry and airbag presence, as well as to check the durability of UDIG anchors and attachments. Eight farside impacts were run to evaluate different versions of the CATCH bag, as well as to check durability of UDIG attachments in side impact.