Kolt, an infant with down syndrome, enjoys swinging but is in need of a safer swing that can also be used as a feeding chair. Since the child is on oxygen and also cannot hold his head upright, these needs must also be accommodated in the design. Lastly, the family would like this chair to be able to grow with their child so he can use it for years to come.
Kolt is a six-month-old with down syndrome who enjoys swinging. His mother would like a safer swing that can better secure him to the swing. The swing should also function as a high chair for feeding Kolt, so its height should be adjustable and its position able to be fixed from swinging. After Kolt is fed, he must be reclined at a specific angle; the swing seat should be able to recline to meet this need. Because Kolt currently uses oxygen, the swing must accommodate his oxygen cord in a safe and secure manner. He also has difficulties keeping his head upright, so some form of head restraint would be necessary during feeding. The chair should be able to grow with Kolt so that it can be used for years to come. It would be beneficial to the family if the swing frame could come apart for easier transportation if necessary. In addition, the swing should be compact in size and relatively lightweight because of some space constraints and for mobility from room to room.
Infant swings on the market are not strong enough or made to change in size as the child grows. An infant swing would be quickly outgrown and adapting an existing swing would be difficult to meet design requirements for size, strength, height adjustment, oxygen cord restraints, and reclining and locking ability while still being safe.
Safe and comfortable child harnesses are available if the decision was made to construct the swing seat ourselves; however, there would be some difficulty in adequately attaching the harness to the rest of the seat in a manner where it is still adjustable for size and is positioned correctly.
Most toddler rocker seats function well but are not made to support the size and weight of a 50 lb child. An existing rocker could be a model for our swing if such a design is acceptable to the family. Rockers on the market have a seat that is fixed to the frame making reclining separately from rocking impossible. A reclining function is not something that could be easily added to a rocker on the market.
Frame Design Concept 1
Connecting Rod Concept 1
Seat Concept 1
Frame Design Concept 2
Connecting Rod Concept 2
Seat Concept 2
Frame Design Concept 3
Frame Design Concept 4
Our design process began by meeting with Kolt’s early intervention service coordinator. We discussed the specific requirements our design needs to meet. These design requirements along with the requirement to swing include a way to adjust the swing height, a locking mechanism to prevent swinging, the ability for the seat to adjust to different positions, a head restraint, safety harness, and oxygen cord restraint. Additionally, the family would like the swing to be able to fold or come apart into pieces for easy transportation and be light enough to be moved across the home either by sliding or rolling.
Once we were aware of the design requirements, we developed design specifications such as frame dimensions and overall swing strength. With design specifications in place, existing swings, seats, and restraints were researched. Conceptual designs were created for the swing frame, swing seat, locking mechanisms, and oxygen cord restraint. Our conceptual designs included an A-frame, cantilevered frame, an on-floor rocker, and an on-floor glider swing.
We presented our conceptual designs and product research to Kolt’s family along with his service coordinator. Together, we evaluated how each concept meets the design requirements and narrowed down our designs by prioritizing needs. Strength, comfort, safety, accessibility, and ease of use were the primary concerns of the family. With these things in mind, the decision was made to build a cantilevered frame with a purchased car seat to be used to meet the safety and reclining requests.
After a conclusion was reached on our final design, we modeled our design and performed finite element analysis (FEA) on the swing frame. Calculations were also made to find overall product weight and tipping point. Each of these analysis reinforced our design decision before moving forward into construction.
The swing will have a number of components: a cantilevered frame, swing arm, seat frame, and a purchased seat. When assembled, the swing will follow a one dimensional path normal to the cantilever arm of the frame. The locking mechanism will be incorporated into the swing arm. The height adjustment will be done by the frame itself
Frame- The swing frame will be cantilevered to allow one side of the swing to be left open for accessibility to the swing. A cantilevered frame maintains the strength required to support the weight of the swing and the child now and into the future. The swing frame will be constructed of steel square tubing. The dimensions of our frame (5’x 4’x 3′) will prevent tipping. In order to further prevent tipping, the top bar from which the swing will hang from will only partially extend the dimension of the overall frame width. For ease of transportation, the frame will have a set of wheels and will disassemble into three manageable pieces. Regularly spaced holes will make the two pieces of the frame capable of adjusting to different heights
Swing Arm/Seat Frame- The swing arm and seat frame will be constructed of steel square tubing. Upon finalizing our design, the decision was made for the swing arm and seat frame to be one piece. A one piece construction will ensure the swing does not twist and a single motion will be maintained across the swing path. The swing arm will wrap around the seat with one side open so the seat can be easily positioned onto the seat frame and so that taking Kolt in and out of the seat is as easy as possible. The swing arm will be mounted to bearings on the frame. Passing a pin through the swing arm is an easy but effective way to lock the swing into the down position. To allow the seat to be positioned and removed easily, the seat will be secured on top of the seat frame.
Seat- The swing seat chosen in our design will be a car seat. Upon evaluating the different design requirements needed for the swing seat, a fabricated seat would be very difficult to fabricate and likely under-perform when compared to a purchased seat. The purchased car seat will be safe, comfortable, restrain Kolt correctly, and will also be able to grow with him and recline as needed. The seat will be implemented into our design unchanged to allow the family to use as a functioning car seat.
Throughout the fabrication process, different components were inspected for safety in handling and strength. Components critical to the structure of the swing were subjected to loads beyond that which is expected in its function. The swing frame and swing arm were each loaded in excess of 150 lbs and then examined.
The pieces of the swing all fit in the back of a pickup truck that was drove to the family. Once we arrived, the swing was assembled in the home and all areas of concern and safety precautions were described. Any questions by Kolt’s mom were answered.
This swing should only be operated with the designed car seat in place and with both seat belts in place and tightened. The swing is not intended for large angles of swing. Never attempt to adjust the car seat or swing height with the child in the car seat. Always follow the car seat manufacturer’s instructions and guidelines. Do not use the device unless supervised by an adult that has been fully understood the safe use of this product.
This project has been very rewarding. Being able to follow the engineering process from start to finish is a great experience in becoming an engineer. Also, it is great to work in the machine shop and gain important skills. Knowing the process of fabrication helps in the design process when considering what can and cannot realistically be done when manufacturing. This is something that we should have considered more. Challenges arose during fabrication which may have been more easily avoided if more consideration to fabrication had been given during the design process. Overall, all the time and energy spent on this project were well worth it after seeing the smile on our child’s face.