Hi y’all,
For the second homework the task is to come up with 5 solutions for a assistive swimming device to an 16-yr old young man, Liam, that suffers from severe ataxia. Ataxia is a condition that impairs voluntary coordination of muscle movements (if you want to know more about ataxia is click here).
There is a pool in the backyard of Liam’s home, which offers him enjoyment. In addition, there is some relief from the struggle of supporting and coordinating his arms and legs when in water due to the buoyancy effect. Despite looking, his family and therapists have been unable to find a floatation device that supports his unique physical needs. As a result, he must be supported by caretakers. Currently, it takes two adult helpers to safely support him in the pool.
From Liam’s needs we can elaborate the requisites for the design:
- The support must allow the majority of his body to be underwater, including his trunk, legs and possibly arms, without allowing his neck to be submerged or allowing his head to drop into the water.
- The swim support should be easy to maneuver by supporting adults. In particular, it should be easy to assist Liam into and out of the support and it should be easy to guide Liam around in the pool.
- An ideal position for Liam would be upright or semi-reclined.
- Trunck support should be significant, so that he could not fall forward, backwards. or to the side.
- Cost is a consideration, but should not drive the design.
- The swim support should tolerate pool water and storage outside in the Houston weather.
Following the engineering design method my approach started by brainstorming and sketching. Below there are pictures of the result of the brainstorming.
After the brainstorming I evaluated the solutions in terms of feasibility and the requisites for Liam. Then I chose the 5 best ones, developed the sketches a little further and prototyped them.
The five chosen solutions are:
- Upgraded life vest
- Underwater walker
- Lily pad float
- Floating armchair
- Triangular float
The first solution is the upgraded life vest. It consists basically of a life vest with a circular float and the trunk support.
The buoyancy is provided by the life vest and the circular float. The circular float is attached to the vest on the shoulder height and it provides the required stability to the device and prevent Liam’s head to drop in the water.
An important feature of this design is the trunk support structure designed to help Liam keep his body in the upright position. This support could be made out of hard plastic, stainless steel or another kind of corrosion resistant metal.
The prototype is shown below:
This solution provides a good freedom of movement for the user, but the trunk support is not ideal.
The second solution is the underwater walker. Since the assistive device will be used on a pool, that has a regular bottom and its relatively shallow, not deeper than 6 feet, using a walker is feasible.
The design consist on a simple structure, made by welding stainless steel bars with whels on the bottom. For this solution Liam will be supported on the walker by resistant fabric strips.
The sketch and the prototype are shown below
The third possible solution is the Lily pad float. It consists in a big ringlike float where the user is placed in the middle, supported by fabric strips.
It is noticeable that this design is able to provide excellent buoyancy and stability allowing for great freedom of movement, in the other hand it is weak in terms of trunk support and maneuverability.
The fourth solution is the floating armchair. It is composed by a corrosion resistant structure, made of stainless steel, for example, with a permeable fabric seat. The buoyancy is provided by a cylindrical float positioned around the arms of the arm chair as shown below:
An important feature of this design is the removable float on the front of the armchair. During use in the pool this float is firmly attached to the structure, but this float is removed when the user is getting in or getting off the chair, making it easier to use the solution.
In addition, this solution provides good trunk support, good buoyancy but does not allow a good freedom of movement.
The fifth and last solution is the Triangular Float. It consists of three floats arranged in a triangular shaped connected by a rigid stainless steel structure. In the center of the triangle there is a permeable fabric seat connected by the structure with rigid support, also made of stainless steel.
This solution is able to provide good trunk support, good stability and good buoyancy while still allowing for some freedom of movement.
By analyzing all solutions, we can see that there is a trade-off between freedom of movement with respect to stability and trunk support. The best solution for the user will be defined by finding the optimal point in stability, trunk support and freedom of movement.
Thanks for your attention, see you on the next post.
Lucas
