The goal of this project was to develop a wheelchair stair climber to help manual wheelchair users navigate their environments safely and with greater ease. This device addresses the challenge that stairs pose to our client and other wheelchair users, who have difficulty accessing a variety of spaces due to the lack of accessible infrastructure. The StepFree stair climber, operated with assistance, improves accessibility for our client.

During the design process the key requirements considered were smooth and stable operation, compatibility with different staircases and different wheelchairs, and affordability for the client. Additional criteria, such as cost, manufacturability, portability, force reduction ability, user comfort and safety were also evaluated. A tracked wheel design, inspired by high traction mechanisms like those in tanks excavators, best met these requirements.

The StepFree stair climber consists of a dolly-like frame, in which, the user in their wheelchair is secured facing away from the stairs. The frame features tracked wheels which are fixed at an angle such that they can rest on the stairs and transport the device up or down. To achieve controlled and smooth movement up and down the stairs, a button-controlled motorized system, powered by a lithium-ion battery, was used. This system allows the user to be safely transported with minimal force required by the operator.

The StepFree stair climber successfully passed the weight capacity test, carrying over 90 kg of weight without any detectable deflection. Additionally, the device met all collapsible size requirements and had an average device set up time of 4 minutes and 30 seconds, well within the desired time frame and the electrical housing proved to be water-resistant. The device was able to be adjusted to accommodate most wheelchairs tested in a width range of 40-70 cm. Unfortunately, the team was unable to test for the operator force input requirement, number of stairs accommodated and battery life under load, due to the tracks not rotating in the completed assembly. As a result, these tests were considered failed and reported in the verification procedure.

The total project cost was $1,844, reflecting the expenses of a first-generation prototype. However, with industrial-scale manufacturing and custom-made parts, the final product price can be significantly reduced. In future iterations or modifications of this device, it is recommended that a lighter-weight track system and a more powerful motor be selected to better suit the application. A lighter material is recommended for the frame to increase ease of transport, and modifications to the frame and wheel bracket dimensions would increase the range of wheelchairs compatible with the device. By addressing this specific accessibility challenge, the StepFree stair climber has the potential to improve the lives of other manual wheelchair users facing challenges in similar environments.