SP-5c: Development and Evaluation of Adult and Child WIRS Prototypes

Co-Task leaders: Miriam Manary, MS (bioengineer, PhD Student), Linda van Roosmalen, PhD (industrial designer/rehabilitation scientist)

Co-investigators: Matthew Reed, PhD (mechanical engineer)

Other participants: Gina Bertocci, PhD (bioengineer, research scientist); Hoveround (wheelchair manufacturer); Mark Schmeler (clinician, consumers); Mike Nordquist, Sunrise Medical (wheelchair manufacturer); Lucy Spruill, United Cerebral Palsy, Pittsburgh (consumers)

Duration/ staging of task: This 24 month research task will be conducted in months 36 to 60 of the 60 month RERC cycle

Design of development activities

The overall goal of this task is to develop WIRS prototypes, which are integrated into commercial wheelchairs. This task will be conducted in close collaboration with wheelchair manufacturers. The objectives of this Task include:

  1. Utilize SP-5b sled testing and computer simulation results to develop commercial wheelchair mounted WIRS prototypes. These prototypes will be developed for pediatric and adult users in close collaboration with wheelchair manufacturers.
  2. Use sled impact testing to evaluate WIRS prototype compliance with occupant injury criteria from General Motor Injury Assessment Reference Values (GM-IARV) and SAE J2249 WTORS test criteria (NHTSA-GM, 1983; SAE, 1996). Modify WIRS prototypes, as needed, and evaluate these changes using solid modeling and FEA. Construct a second prototype for adult and pediatric users.
  3. Conduct a comfort and usability study among appropriate wheelchair users (based on the tool developed in Task SP5-a) to evaluate ease of use and restraint comfort of the WIRS prototypes as compared to a VMRS.
  4. Conduct a second 20g/30mph sled impact test of the WIRS prototypes to evaluate product safety and occupant protection.
  5. Disseminate evaluation protocols for WIRS to standards organizations. Document dynamic test procedures for WIRS to assist standards organizations in the development of standards for improved wheelchair occupant protection.
  6. Develop informative guidelines in the form of educational documentation to convey the task results to clinicians (guidelines how to specify, fit, adjust and customize WIRS for individuals).

Environment for development and testing

Computer simulation of both pediatric and adult WIRS designs will be conducted at the University of Pittsburgh’s Injury Risk Assessment and Prevention laboratory (IRAP) and at UMTRI. Solid modeling and FEA will be utilized by investigators as needed, to assist manufacturers in their designs. Development of the WIRS structure will take place primarily at wheelchair manufacturer’s facilities and, in part, at the machine shops available at the University of Pittsburgh and UMTRI. Frontal 20g/30mph sled impact testing using an instrumented 50th percentile male and 6year old child Hybrid III ATD will be conducted at the sled test facility at UMTRI. Usability testing with the WIRS prototypes using actual wheelchair users will take place at UMTRI and the University of Pittsburgh.

Cost-effectiveness and usefulness

Task SP5-a and SP5-b will establish user needs and include the development of WIRS design guidelines for adults and pediatric wheelchair users. Task SP5-c will develop and evaluate WIRS prototype designs working in close collaboration with wheelchair and restraint manufacturers. The results of Task SP5-c will be a prototype adult and pediatric WIRS developed and evaluated with manufacturers’ and user input throughout the design process. FEA and computer simulation techniques are used to reduce the number, and therefore, cost of sled impact tests. The development of demonstration prototypes evaluated using state-of-the-art techniques will highlight the anticipated improvement in occupant safety as compared to vehicle-mounted restraints. It is also anticipated that the usability testing will demonstrate the usefulness and advantages of the WIRS over vehicle mounted restraint systems. The anticipated improvements in ease of use and superior belt fit will likely lead to increased restraint usage and therefore, improved occupant protection.

Potential for commercial development

Close collaboration with wheelchair manufacturers in the development of prototypes will ensure a fast and low cost technology transfer of the developed WIRS technology, decreasing the time necessary to make WIRS available to wheelchair users. Input obtained from consumers in our usability study will further promote useful and marketable commercial WIRS products. Transfer of test methods and findings to standards organizations will also aid manufacturers with the development and commercialization of WIRS products.


NHTSA-GM (1983). General Motors submission USG 2284, app. E, NHTSA. Docket 74-14 Not. 32.

SAE (1996). SAE J2249 Wheelchair tiedowns and occupant restraints (WTORS) for use in motor vehicles, SAE.

Progress Report May 1, 2005

Progress to date for the adult population

Several seat integrated lap belt concepts have been developed and are currently in the prototyping and evaluation phase. An ergonomic study is underway for one of the concepts to investigate if a varying size restraint is required for use by various sized occupants.

A user testing protocol is also under development to investigate the ease of use of the prototypes in comparison with commonly available lap restraint devices.

Dynamic evaluation of these prototypes is expected to take place later in 2005.


Progress to date for the pediatric population

Guidelines for pediatric integrated restraints will be evaluated through the development of prototype hardware and dynamic testing of experimental systems.

Progress Report May 1, 2006

Two concepts of pelvic restraints for adult use have been developed. For one concept additional funding has been sought for technology transfer purposes. For the other concept, we originally had a commercial partner to assist with prototyping. However, due to a conflict regarding a license agreement, this partner has withdrawn from the project. A new partner is now being sought.

One concept is in detailing phase and should be ready for prototyping this summer. Sled testing is expected to take place in the fall of 2006, demonstrating the feasibility of this wheelchair integrated pelvic restraint. The pelvic restraint is innovative because a rotational buckle was used instead of a commonly used push button. Additionally, an adjustable stiff stalk is attached to the buckle to allow for one handed engagement and release.

This project also investigated the feasibility and design criteria for wheelchair-integrated (i.e., wheelchair-anchored) belt-type occupant restraint systems for pediatric wheelchair users, with special emphasis on five-point harness systems for children under 23 kg (50 lb) mass. The initial portion of the project defined design guidelines for integrated restraint harnesses using information from the federal motor vehicle safety standard for child restraint systems (FMVSS 213), from well established principles of occupant restraint, from ease-of-use issues for child restraint systems based on field observations, and from studies of automotive-seated child anthropometry.

During this year, the draft version of these design guidelines was used to implement five-point harnesses obtained from current FVMSS 213-compliant child safety seats on current pediatric commercial wheelchair products. The prototypes were frontal-impact tested to evaluate the crashworthiness of each prototype based on established performance criteria from FMVSS 213. The tests also provided quantitative information on forces applied by harness shoulder belts to the wheelchair seatback for use wheelchair manufacturers in designing their pediatric products for use with fully integrated restraint systems. The final phase of the effort will develop similar prototypes harnesses for lightweight folding wheelchairs.

Based on the information collected during the process of developing and testing these prototypes, the design guidelines were revised and improved, to include strength requirements and issues specific to wheelchair encountered during the prototyping process. These guidelines are now being used to augment ANSI/RESNA WC19 with design and performance criteria for wheelchair-integrated, five-point harnesses for wheelchairs used by children under 23 kg (50 lb).

Last updated: August 18, 2006