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The name of the child we are involved with is Miguel. Most days, Miguel crawls along the carpet flooring of his house, sometimes pulling himself up momentarily by relying on the support of a nearby table or couch. The therapist and family thought a walker would work great for Miguel, allowing him to start learning to take his first steps, gaining lower body strength, and developing good posture.
Currently three years old, Miguel shows delay in the development of his gross motor skills. With that in mind, our chief goals for this project are to provide Miguel with the support he needs to learn how to walk and explore the outdoors he loves so much. Working hand-in-hand with the family’s therapist Ms. Cruz alongside Miguel’s mother, our mission is to design, model, and assemble an adaptive walker suitable for Miguel.
Since we had little to no prior experience designing walkers, we started by engaging in some basic research. We learned that most walkers offer features such as height adjustable legs and are sometimes made to be foldable. At this point, we started asking some necessary questions amongst ourselves in order at the crux of what we want from this project.
Question 1: Wheels or no wheels?
Walker vs. Rollator
Answer 1: Choosing a rollator, a rolling walker, was a relatively easy choice since the physical specifications of an ordinary walker are probably too much for Miguel.
Question 2: How many wheels?
2-Wheel vs. 3-Wheel vs. 4-Wheel Walkers
Answer 2: After some careful deliberation, taking the mother, the therapist Ms. Cruz, and even Miguel’s opinions into account, we moved forward on the assumption that a 4-wheel walker would best satisfy everyone, offering a middle ground between the rigid design of a 2-wheel walker and the mobility of a 3-wheel walker.
Question 3: What should the general frame of our design resemble?
Answer A: We referenced the traditional design of a Klip 4-wheel walker produced by Circle Specialty.
Answer B: We referenced the design of the 4 Wheel Rollator walker produced by Drive Medical.
Answer C: We referenced the outdoor design for the Klip 4-wheel walker produced by Circle Specialty.
The first concept design remains heavily based off of the standard Klip 4-wheel walker design. That being said, our concept design intends to convert a Klip walker, which is typically designed to be pulled by hand grips on the side, into a push model. In order to realize this design, the front wheels must be switched out for back wheels and vice-versa. Typically, turnable wheels are positioned in the front of walker to allow for a greater degree of maneuverability. Along with that, there are foot activated wheel brakes on two of the front walker wheels that can be used to lock the walker in place. The most distinctive feature of the depiction of a seat strap or harness to support Miguel’s weight. The last major adjustment to original design was the addition of two handles protruding out of the back, reminiscent of the back part on a wheel chair.
The second concept design takes one of the standard variations on a lightweight walker design and strengthens the overall structure. By overhauling a preexisting compact walker design and adapting it to suit Miguel’s needs, there are several unique benefits to this design. One of the most notable differences between this design and the other ones is the presence of hand activated breaks attached to the rear handle grips. With these, breaking becomes much more convenient. Another point of interest lies in the fact that the front of this design is significantly more open than the previous design. For this design, Miguel can be placed into the walker from the front. In addition to that, this design also has room to accommodate additional features to support Miguel such as a seat or backrest.
Similar to the first concept, the general frame of the design was greatly inspired by the Klip walker, again making many of the same changes as was done with the first concept design. However, the specific reference for this one was oriented towards outdoor use. For this design, we considered how the duality rigid back straps and a flexible seat may improve Miguel’s experience outside. The walker possesses foot brakes to lock the wheels in place. This time these brakes are positioned on the back wheels for ease of use. Moreover, the walker offers areas on the side and front bars for which Miguel can hold onto.
The selected design that we finally chose is a four-wheel walker equipped with 8-inch wheels. We selected this size of wheel because the walker is supposed to be used indoors and outdoors. The two front wheels are swivel wheels, and the back ones are straight, to allow a higher degree of mobility. In order to support Miguel’s weight, we will design a piece of trunk support. We will use bicycle parts to set up brakes on the handles of the walker so that the person accompanying Miguel can brake. The brakes affect the back wheels.
The walker will include a handlebar for Miguel to push/pull himself up. Because of this, some amount of stress will be introduced in the handlebar. We assumed a force of 100lb would be applied to the handlebar and that it would act at the middle.
Assuming the product is made of an aluminum alloy with an allowable stress limit of approximately 40 ksi, the handlebar will be able to withstand Miguel’s weight.
We felt it was important to calculate the minimum force required to push the walker to ensure that Miguel can push it himself. Because the walker will be used outside frequently, we assumed the surface to be gravel, as that is probably this highest friction value the walker will encounter.
Miguel should be more than capable to push the walker, even through a surface like gravel.
Since the goal is for Miguel to rely less on the supports as he learns to walk, it is useful to understand the stresses flowing through the trunk support. Most notably, the trunk support is bore entirely by two small aluminum weld tabs.
As such, the load passing through the weld tabs is at an acceptable threshold.
