Design and build an adaptable push-behind walker for a three-year-old child with a motor delay focusing on stability, adaptability, and transportability.
The child in need has a developmental delay, more specifically a motor delay causing issues walking without supportive assistance. Current products available for purchase, including push-behind walkers and gait trainers, are not tailored well to the child’s needs causing instability and general dislike. The focus is to design and build a support-assistive, push-behind walker that is customized to the child’s current height, adjustable for future growth, stable to prevent tipping, collapsable for portability and has an interactive element.
Simple push-behind walkers for toddlers found at retail stores do provide the supportive assistance intended for our design but are cheaply constructed and have little to no customizable features to accommodate growth of the child. The parent mentioned these models are not properly sized for the child and have had issues tipping over.They do incorporate interactive features which make the product more appealing to a child who otherwise might avoid using it.
Rehabilitation companies, such as HOGGI, provide products with more robust design features like collapsable frames, height adjustment, and braking technology. The larger wheels are designed for safe use outdoors. Rugged design and increased structural integrity are important to our design process to create a product that is safe and long-lasting.
The current gait trainer used by the child utilizes an open front with an abdominal saddle for extra support and right/left handlebars. The parent informed us that the placement of the handles did not displace weight in a manner that allowed for enough mobility and that there was a general dislike towards using the trainer, especially after removing the saddle. Our conceptual designs seek to keep the structural integrity of this design and overall stability while avoiding the features mentioned that do not seem to be functional for the child.
This design adapts an existing walker to support the child’s growth and mobility. The handlebar and the linkage between the front and rear wheels are telescoping, allowing the frame to adjust as she grows. A pivot mechanism ensures that when the handle extends and the geometry changes, her weight remains within the wheelbase for stability. The front wheels are redesigned to enable turning, and a support brace is added to evenly distribute the load across all wheels. Additionally, the front panel incorporates a wooden peg board for interchangeable toys, encouraging engagement and play.
Unlike a traditional gait trainer, the walker is positioned in front of the child and does not require a harness or enclose the user, allowing for greater freedom of movement and independence. The design features an adjustable lightweight frame that can grow with the child, ergonomic handles, and durable wheels capable of handling both indoor and outdoor surfaces such as sidewalks, grass, and playground areas. The goal is to create a safe, stable, and practical mobility device that provides support while allowing the child to interact with her environment more naturally.
This design focuses on improved stability featuring a wraparound base-frame, wide rear-wheel base, and a handlebar that doesn’t extend past the base-frame. This also incorporates a collapsable frame, making it easily portable. Swiveling wheels in the front allow for increased mobility.
*image generated using ChatGPT and used to display design features. This DOES NOT represent a final product.
A decision matrix was used in determining the concept to move forward with in the design process. The design specifications have separate scales to introduce a weighted factor for the elements that are most important to the overall build. We arrived at concept 3 and, moving forward, will incorporate features from the other design concepts to improve the overall final product such as the interactive element.
We selected Design 3 with a few details from design 2. We are going to use the design of the frame from concept 3 for the foldability and stability aspects, then details like rubber handles and durable wheels from concept 2.
The proposed design is a pediatric walker intended to assist a young girl with limited walking ability while encouraging independence and stability. The design is specifically for a child between the ages of 3 and 5, with an emphasis on providing a lightweight, durable, and adjustable mobility aid. The design utilizes a front facing configuration, allowing the child to stand behind the frame and use the handles for support without being enclosed. The walker is intended for use in everyday environments, including indoor and outdoor spaces, while providing adequate stability and maneuverability.
The primary structural components of the walker will be constructed using 1in x 1 in T-slotted aluminum framing (McMaster-Carr part No. 4658N14). This material was selected for its relatively low weight, corrosion resistance, structural properties, and modular construction. The T-slotted rails allow frame members to be connected using compatible brackets and fasteners, minimizing the need to weld and simplifying the assembly. The modular design also allows for easy repositioning, replacing, and modifying components throughout the development process. The 1 in x 1 in profile was selected to balance structural strength, overall weight, and cost while maintaining a compact frame suitable for a child.
One of the primary features proposed for the walker is its adjustable height, allowing the walker to grow with the child over time. She is currently 35 inches tall, so the initial frame dimensions will be designed for her current height with room to grow. This will be accomplished by adjusting the length of the vertical frame members rather than adjusting the handle placement. This would allow the upper handle portion to be raised/ lowered while maintaining the general frame configuration. The adjustable mechanism has not been finalized yet, but the modular design and t-slot railing provide flexibility for incorporating adjustable members or interchangeable members. The final mechanism will need to securely lock into position to prevent unwanted movement during use.
The walker will include a wheeled base design to provide stability while allowing the child to move with minimal effort. Wheel size, placement, and configuration will be evaluated to improve mobility while minimizing the risk of tilting. Additional safety considerations include covering exposed aluminum edges, securing mechanical connections, and ensuring the handle surface, while comfortable, also provides a reliable support surface.
Structural analysis will be performed to evaluate the strength and stiffness of the proposed aluminum frame. Although the walker is primarily going to be a balance aid, the design must also account for unexpected situations where the child may apply most or all of her body weight to the handles. We plan to evaluate the bending stress and deflection of the selected aluminum framing using anticipated loading conditions and the rail’s cross-sectional properties. Additional analysis will connection strength, lateral stability, and resistance to tipping. These evaluations will help determine whether the selected frame geometry and components provide adequate structural performance before the physical prototype is constructed.
Throughout the conceptual design process, we have prioritized stability, adjustability, maneuverability, affordability, and ease of manufacturing. The front facing configuration was selected to provide an open walking area without restricting the child’s movement. The decision to incorporate T-slotted framing represents a further development of the initial concept, providing a modular structure that can be adjusted and modified as the child’s needs change. The next stages of development will include determining the appropriate frame dimensions, finalizing the height adjustment mechanism, selecting wheels and handles, and developing a detailed CAD model before manufacturing.
Determining the tipping point is important to evaluate the walker’s stability and reduce the risk of it tipping during use. The general equation is:
F(tipping) = M(resisting)/ height. Using the walker’s resisting moment of 80 lb·in and a height of 17 inches, the calculated tipping threshold is approximately 20.9 N.
We felt it was important to calculate the minimum force required to push the walker to ensure Lainey is able to push the walker. Because the walker is designed to be used indoor and outdoor, we used gravel as our surface in question, as gravel has this highest friction value the walker could encounter.
Finding the max internal force is important to ensure the chosen material (1010 aluminum extrusion) can withstand the forces without breaking or buckling.
The max internal force is 40.41lbf in compression, which is well below what 1010 aluminum extrusion can handle.
