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Our team was tasked with creating an arm-powered swing for a child with spinal muscular atrophy.
The parents of a two-year old child with SMA (spinal muscular atrophy) asked us to make an arm-powered swing that their child could use. They asked that it be portable and that she could continue to use it as she grows. the goal of the project is to give the child a way to improve her upper body strength while using the swing.
– Safety: Safety should always be the number priority especially when dealing with projects that children will interact with.
– Ease of Use: It should not require significant preparation time or upkeep
– Sturdiness: The design should be able to last a long time
– Add arm-powered mechanism without compromising swing functionality
– Portability: The family wants to be able to move the swing easily
– Have the swing be able to accommodate her as she grows
“Spinal muscular atrophy (SMA) is a genetic disease affecting the central nervous system, peripheral nervous system, and voluntary muscle movement (skeletal muscle).” (https://www.mda.org/disease/spinal-muscular-atrophy)
We learned that SMA causes the person to lose nerve cells. Some of these nerve cells are “motor neurons” which control muscles. Without these nerve cells the person has limited mobility and strength due to their muscles not being able to move. As they get older, the condition of the disease causes various effects. The most common is restricting them to a motorized wheelchair with little mobility in the arms and close to no mobility in the legs.
When we met with the family we learned that the recipient of our project actually has surprisingly good strength and mobility for a SMA patient. The parents wanted to build on the progress she already made by letting her work on upper body strength using a swing.
We tried to find examples of “arm-powered swings” on the internet. There were not many arm-powered designs that we could find.
One works by the user shifting the center of Gravity of the seat frame and the other is a glider swing.
A rigid bar with connected 90 degree handles is connected to a suspended chair. The user moves themselves with respect to the handle/rod resulting in an almost pure arm movement swing
This design would utilize a normal child seat with two bars that rise from the arms of the chair and extend through the bottom. A four bar would be formed underneath the chair with weights attached. The child would perform a rowing motion with her arms using the bars to move the weight underneath the swing causing the swing to move.
Similar to design 2 this design focus is on a regular child chair except the child uses their full body with extra help from their arms. Unlike a regular child swing, pulling in the arms would cause the leg rest to rise and the back support to lean back. This alow the child to mimic a more natural swinging motion and possibly develop the proper muscles to use a regular swing in the future.
