STEM 2, spanning from February to May, comprises of a team assistive technology project overseen by Dr. C. The coursework, similar to STEM 1, includes completing an updated logbook, researching as necessary, conducting design studies to inform design choices, and developing a prototype that meets all Level 1 requirements (set at the beginning of the project). This work prepares us to eventually deliver the prototype to Client X and present our learnings at the May Assistive Technology Fair.

PROBLEM STATEMENT: Client X faces significant challenges in using a standard walker to navigate stairs due to its inability to securely rest on individual steps. The limitation necessitates constant assistance from a caretaker, preventing them from focusing on other responsibilities or providing additional support in other areas. The lack of a suitable solution not only hinders Client X’s independence but also places an added burden on their caretaker, highlighting the need for a safer and more efficient walker design for stair navigation. SureStep is designed to solve this problem by creating a walker that is stable and easy to use on stairs. The goal is to help Client X, and others with similar mobility issues, gain more independence while reducing the physical and time demands placed on their caretakers.

DESIGN APPROACH: The following four designs were considered and developed as proof of concepts. We found Design 4 the most practical, efficient, affordable, and overall most likely to fulfill all requirements. While Designs 1-3 were not used, they were essential to the decision-making of the current prototype’s design and served as inspiration throughout the build process.

DESIGN 1: Leg Extension with Solenoid Locking Mechanism (Exterior Tube Extends): The design used an exterior tube extension mechanism secured by an electromagnetic solenoid. The concept was initially modeled using cardboard tubes and a wooden skewer to simulate the locking mechanism. However, the design's reliance on preset heights limited its adaptability to stairs of varying dimensions, failing to adhere to a major requirement. This led to the conclusion that this approach was unsuitable for the final product.

DESIGN 2: Grippy Wheel Mechanism for Leg Extension: The concept explored the use of rubber or silicone gripping wheels to extend the walker’s legs. The proof of concept was built with cardboard tubes and rubber balls connected by a string to simulate a rolling mechanism. While this design showed potential for smooth movement, the locking mechanism proved unreliable, and the wheels lacked the necessary friction to securely support the walker under a user’s weight without the legs retracting. After consultations with Dr. Kevin Crowthers and project mentor Mr. Pavel Loven, it was determined that the design’s limitations in stability and safety rendered it impractical for real-world application. Consequently, this concept was not pursued further.

DESIGN 3: Leg Extension with Solenoid Locking Mechanism (Interior Tube Extends) The design shared many features with Design 1 but reversed the extension mechanism. The interior tube extended while the exterior tube remained fixed, providing more stability by reducing bending under weight. A sensor was proposed to lock the electromagnetic solenoid into a predetermined hole along the exterior tube when the sensor detected ground contact. The proof of concept used a wooden skewer to simulate the electromagnetic solenoid, which locked the interior tube securely at the desired length. Testing confirmed that this design could support the user's weight effectively while maintaining adaptability to varying stair heights. However, the design would require the usage of an entirely new walker frame and extra materials, since it becomes impossible to extend the interior tube of a preexisting walker frame. It was determined that the design’s high cost made it impractical and the concept was not pursued further.

DESIGN 4: Attachment with Button-Controlled Retraction: The concept used a linear actuator as the primary component for adjusting the walker’s leg length, capable of supporting up to 300 pounds without requiring an additional solenoid locking mechanism. The actuator’s flexibility allowed it to adapt to varying stair heights, and a button was implemented to toggle between two modes: an “up” mode, where the linear actuator retracts to assist users in ascending stairs, and a “down” mode, where the actuator extends to aid in descending stairs. The design’s simplicity, reliability, and adaptability made it the most promising choice, and it was selected as the basis for the final prototype.