Kathleen DeSantis Klinich

In 2022, nearly 18.6 million Americans age five and older reported a travel-limiting disability (Firestine, 2024). Among these are an estimated 5.5 million wheelchair users who often experience tra...

Vehicles with automated driving systems may provide substantial benefits to individuals who travel while seated in wheelchairs. Despite the importance of posture data for developing occupant protection systems, limited research has analysed wheelchair user posture in the context of automotive safety. In this study, we obtained three-dimensional postural data of 75 people seated in their personal wheelchairs and generated individualised baseline avatars in automotive posture using HumanShape software. Generated avatars were manually adjusted to match the posture of the field scan, and anatomical landmark locations and segment orientations were analysed relative to wheelchair and participant characteristics. Observed differences in pelvis, abdomen, and knee angles compared to standard automotive posture indicate the prevalence of reclined posture among wheelchair users offset by a more forward neck angle. Significant postural differences were observed based on gender, BMI, and disability. These posture differences have implications for the design of occupant protection systems.

At present, commercial air travel rules do not allow people to sit in their own wheelchairs during flight. However, airline seating often does not meet medical needs. In response to current requests to allow this seating option, we researched the crashworthiness and safety of wheelchairs for potential use in aircraft. For motor vehicle travel, many wheelchairs meet voluntary standards for crashworthiness and safety per RESNA WC19. This project assesses whether WC19-compliant wheelchairs can meet FAA aircraft seating standards when secured using 4-point tiedowns. For the FAA horizontal impact testing, computer modeling indicated that a trapezoidal sled pulse was sufficient to represent the more typical triangular pulse, and that due to the flexibility of the tiedown webbing, the effect of the simulated pitch/roll element was minimal. During the initial two horizontal impact tests, fracture of the left front wheelchair caster was observed. The remaining five wheelchairs were tested with an added vehicle-mounted lap belt and were successful at meeting occupant retention and structural integrity requirements. The outcomes show that it may be possible for people to remain seated in a WC19-compliant wheelchair for air travel without a significant decrement in safety.

Ensuring widespread accessible mobility has the potential to positively impact the lives of millions of people with disabilities by moving and connecting them to what matters, in addition to improving mobility for everyone through the benefits of inclusive design. To enable cross-disciplinary solutions, an overview of several key research areas for advancing the field of accessible mobility will be provided, covering aspects including the accessibility ecosystem, physical and digital methods for improving accessibility, and accessibility safety. Recent advancements and opportunities for innovation will be highlighted, with the aim of developing a holistic inclusive transportation architecture, leveraging the ongoing and future transformation of the industry.

The objective of this study was to develop and validate finite element (FE) models of commercial manual and power wheelchairs, as well as related test fixtures and tiedown hardware, to provide tools for designing integrated wheelchair seating stations for automated and other vehicles. The manual wheelchair model is based on a Ki Mobility Catalyst 5, and the power wheelchair is based on a Quantum Rehab Q6 Edge 2.0 with Synergy Seating. A 3D Sense scanner was used to capture wheelchair geometry. Wheelchairs were disassembled into components to collect masses and additional dimensions. These geometric data were used to construct computer-aided design (CAD) models of each product. Additional fixture models were generated from available drawings for the surrogate wheelchair base (SWCB), surrogate wheelchair 4-point strap tiedowns, traditional docking hardware, and hardware meeting Universal Docking Interface Geometry (UDIG). Models were constructed in LS-DYNA. For each wheelchair, between 1 and 3 dynamic sled tests in front, lateral, and rear directions were conducted for a total of 13 tests with varying wheelchair securement methods to obtain validation data. Frontal and rear impact tests used a Hybrid III midsized male, whereas the side impact tests used the ES-2re. Validation sled pulses were nominally 20 g-48 km/h for frontal tests, 10 g-22 km/h for lateral tests, and 14 g-30 km/h for rear impact tests. CORrelation and Analysis (CORA) scores were calculated for head and chest resultant accelerations. Validation results include comparison of component masses, overall wheelchair and anthropomorphic test device (ATD) kinematics, ATD head and chest signals, and calculation of CORA scores for head and chest resultant accelerations. For the 2 wheelchairs and SWCB, total model mass was within 1% to 4% of physical mass. Across the 13 test conditions, head acceleration CORA scores ranged from 0.71 to 0.92 in 8 conditions and from 0.52 to 0.67 in 5 conditions. For chest acceleration, CORA scores ranged from 0.73 to 0.96 in 8 conditions and from 0.51 to 0.67 in 5 conditions. In addition, residual deformation was similar between test and model in conditions where it occurred. These publicly available tools will allow vehicle safety engineers to design equitable occupant protection systems for occupants who travel while seated in their wheelchairs. They will also be the baseline for ongoing research to develop parametric wheelchair models for additional occupant sizes.

Objective: Previous research on occupant protection systems for wheelchair-seated occupants focused on frontal impacts, while similar studies on side impacts are very limited. The objective of this study was to identify the major injury concerns for wheelchair-seated occupants in side impacts and develop restraint systems to mitigate such injury concerns. Methods: Seven sled tests in side impact conditions were first conducted at 30 km/h with a 24 g peak deceleration. An ES2-RE ATD and surrogate wheelchair base (SWCB) were used in all tests, which varied armrest design, width of the SWCB, and wheelchair tiedown conditions. These sled tests set up the baseline performance and provided validation data for computational models. A set of validated MADYMO models were then used to investigate the safety concerns and potential restraint solutions for wheelchair-seated occupants in side impacts. Simulations covered nearside and farside impacts, inboard or outboard D-ring locations, varied wheelchair locations relative to the side door, varied seatbelt anchorage locations, and a few Center Airbag To Contain Humans (CATCH) designs. Finally, another set of sled tests were conducted to demonstrate the effectiveness of varied CATCH designs for protecting wheelchair-seated occupants in farside impacts. Results: Simulations suggested that wheelchair-seated occupants might fall from the wheelchair in farside impacts, while in nearside impacts the seatbelt and curtain airbag can provide reasonable protection to occupants using wheelchairs. The CATCH design, a curtain airbag mounted to the roof centerline with tethers attached outboard of the wheelchair station, was effective at preventing the ATD from falling off the wheelchair. Results from sled tests to iterate CATCH parameters confirmed that the concept was effective at retaining occupants seated in wheelchairs under farside impact loading. Conclusions: This study is the first to investigate wheelchair-seated occupant protection in both nearside and farside impacts. The injury concerns identified in farside impacts and the CATCH design can potentially help improve the protection of wheelchair-seated occupants in side impacts in the future. The CATCH design has potential to improve farside protection for occupants in traditional seating.

This literature review summarizes wheelchair transportation safety, focusing on areas pertinent to designing automated vehicles (AVs) so they can accommodate people who remain seated in their wheelchairs for travel. In these situations, it is necessary to secure the wheelchair to the vehicle and provide occupant protection with a Wheelchair Tiedown and Occupant Restraint System (WTORS). For this population to use AVs, a WTORS must be crashworthy for use in smaller vehicles, able to be used independently, and adaptable for a wide range of wheelchair types. Currently available WTORS do not have these characteristics, but a universal docking interface geometry and prototype automatic seatbelt donning systems have been developed. In the absence of government regulations that address this situation, RESNA and ISO have developed voluntary industry standards to define design and performance criteria to achieve occupant protection levels for wheelchair-seated passengers that are similar to those provided by conventional vehicle seats.

Identifying current occupant travel patterns can inform decision making regarding the design, regulation, and occupant protection systems helpful for automated vehicle systems and mobility services...