Aircraft Boarding Wheelchair

For our Capstone Project, my team was contracted by Tangent Design Engineering Ltd to develop a lightweight boarding wheelchair emphasizing competitive retail pricing and intuitive operation. The client requested a setup time of less than 90 seconds, and required that the chair fit in overhead luggage compartments when folded. In order to maintain market competitiveness, emphasis was placed on compliance with SAE ARP 4120 standards for foldable onboard wheelchairs.

This project was completed under the mentorship of Dr. Kajsa Duke, through course MECE 460 at the University of Alberta, and was awarded the Precimax Design Award for being one of two top projects for the semester by a panel of professors and industry professionals.

Contributions

  • Problem Definition
  • Concept Development
  • Detailed Design
  • CAD
  • Design Optimization

Collaborators

  • Anthony Decesare
  • Malinda Guo
  • Calvin Jee
  • Vincent Palamarchuk
  • Craig Radke

Poster Final Presentation Project Reports

The Problem

Boarding wheelchairs are used for transporting airplane passengers to and from their seats because aisle constraints prevent the use of a standard wheelchair. Today, the Air Carrier Access Act requires all U.S. and foreign air carriers with more than 60 seats to carry an on-board wheelchair.

After interacting with wheelchair users, a maintenance specialist, air attendants, and experiencing commonly-used boarding wheelchairs for ourselves, we identified the following drawbacks:

  • They are heavy (most exceeding 11 kg), in an industry that is focused on weight reduction. Greater weight results in increased fuel costs for the airlines and poses a risk of injury to air attendants.
  • They are complex and cumbersome to use. Interviewed air attendants sought an intuitive setup process lasting at most 90 seconds.
  • They can be difficult to store. Since the airlines are required to carry them on-board, a lightweight wheelchair that can be stored in the overhead compartments is prefered.

Our Solution

Weighing only 7.3 kg, our lightweight concept features a thermo-formed seat (1), a collapsible back-rest (2), and a restraint system (4). The tie-rod (10) and slider mechanism (3) provide collapsibility, as well as seat-height and angle adjustability. Fixed rear wheels (7) and front casters (8) allow stable movement when the wheel-locks (9) are disengaged. The extendable footrest (5), functioning also as a frontal shock absorber (6), accommodate a wide range of users.

Lightweight & Competitive

The chair is designed such that a 150% mark-up on capital-cost yields a retail price that falls within the ±10% market average price range of $1950 to $2600 for existing chairs. Moreover, the low weight of the chair will allow an airline to recover its capital cost within 2-3 years from purchase from weight-based fuel-savings. Hence, the product provides a financial incentive to both manufacturer and customer without sacrificing usability and collapsibility.

Intuitive & Easy to Store

A significant advantage of this design over existing alternatives is its highly intuitive collapse procedure. The operator pulls on a cord in the rear (beneath the seat) to disengage the locking mechanism which allows the wheelchair to collapse into the folded state under its own weight. I designed this mechanism with inspiration from baby strollers.

Once collapsed, the chair can be stored length-wise in an overhead compartment. This package size was acheived through geometry optimization. I programmed a custom algorithm to optimize the 14 lengths characterizing the 7-bar linkage of the collapse mechanism to minimize the collapse height of the chair while maintaining stability in the upright position for all intended users.

Adjustable & Accommodating

The seat was designed to be adjustable to meet the varying needs of users and operators. Highlighted features include:

  • Body dimensions of the flight attendant and passenger ranging from a 5th percentile female to a 95th percentile male were accommodated when fixing the size of the wheelchair and the locations of handles and controls. Ofcourse, the aisle width was an overriding constraint in some cases.
  • Passenger transfer from the wheelchair to the plane seat is more convenient with matched seat heights. Different seat heights can be acommodated by simply changing one link in the assembly.
  • The chair features some additional flexibility, such as the footrest location, and the backrest angle.

Acknowledgments

I would like to thank the following individuals for playing an important role in the completion of this work:

  • Josh Abbott and John Person, Tangent Design Engineering
  • Dr. Kajsa Duke, Advisor, University of Alberta
  • Tony, Medichair South Edmonton
  • Beverley Matthiessen, Alberta Committee of Citizens with Disabilities
  • Ana Lucas Osma and Louise Miller, Wheelchair Users
  • Sarah Cox, Edmonton International Airport
  • Charlene Abbott, Flight Attendant