Our project aims to create an adaptive spoon to help a child diagnosed with CDG, a genetic disorder similar to cerebral palsy, eat in a hassle-free manner.
The child we are working with is a 5 year old
with a diagnosis of CDG, resulting in ataxic (jerky and
uncoordinated movements) similar to what you would see
with cerebral palsy. The family has been working on self
feeding for several years now but she continues to display
decreased distal motor control as well as decreased brain
to body connection to scoop foods and bring them to her mouth
without spilling. Therefore, we are designing an
adaptive spoon that would accommodate decreased
mobility in her wrist/forearm and uncoordinated movements to
help her successfully bring foods to mouth without
maximal assistance from caregiver.
Following our meeting with the child’s occupational therapist, we gained valuable insights into the challenges the child faces while eating and identified essential considerations for our design. Additionally, we received a series of video recordings capturing the child’s eating experience, which proved instrumental in shaping our design approach.
Once we brainstormed three initial design concepts, we researched how to effectively implement each design. We found multiple companies that have developed motorized spoons that stabilize automatically for handicapped individuals. We also looked for a design that could retain the mobility of the motorized spoons while being completely mechanical.
This design allows the head of the spoon to rotate inside the handle so that when lowered against the plate it will be in a position to scoop food, and when the child raises it to her mouth, it will be free to tip so she does not have to rotate her wrist.
Related Design Concept:
Related Design Concept
Design Review Process
Each idea was rated on a scale from 1-5 in each of the following categories: Ease of Fabrication, Cost, Food Safety, and Usability. Each of these categories is described below the decision matrix to provide a clear understanding of the factors considered in each design component. In order to provide a diverse set of designs, each team member was responsible for developing a unique solution to the problem as shown above. After the ideas were presented and discussed to the group, the team worked together to rate each factor for each design (1=worst, and 5=best).
Note: Each category is weighted differently with Usability holding the highest weight of any category. Despite having a numerical analysis of the factors, group discussion and collaboration with the family is what will ultimately determine what design is chosen.
Ease of fabrication aims to determine how simple the spoon would be in design, manufacturing, and assembly. This also considers the machining process for any custom parts.
Cost aims to determine the monetary cost associated with all materials, time, and equipment used to make the spoon. This not only includes the fabrication process, but the design and prototyping phases of the project.
Food safety aims to determine the health and safety risks posed by the design. This includes not only what materials are food safe but also whether or not the materials are dishwasher safe and easy to clean.
Usability aims to determine how effective the design will be. This category was filled out by our group’s contact for the project so that the design we choose has a good chance of being effective.
The results of the design matrix conclude that the rotating spoon is the best design due to its simplicity and usability.
The Rotating spoon was chosen due to its promising stability and free rotating inner shaft. It is designed so the spoon head’s center of mass will keep it level despite rotational movement on the handle. This will ensure that any food will stay on the spoon and give the child more mobility.
There will also be different attachments for the spoon handle. This will allow for easy cleaning of the spoon as well as the ability to eat different types of foods. These different attachments can be swapped out via the BNC connector type joint. This connection will allow for easy swapping as well as rigidity during use.
On the back of the spoon, there is a cap that can be unscrewed to reveal the internal shaft that allows the spoon too rotate. Not only does this cap constrain the shaft preventing it from falling apart, but it also allows for an easy access port for deep cleaning the spoon.
Starting with the handle, the Rotating spoon is designed to match a current handle the host family is already using; however, it will be hollow containing the rotating shaft. The shaft will be a composite of two materials: steel on the bottom half and plastic for the top half attached by an epoxy. This is to help keep the center of mass toward the ground, which should keep the shaft from rotating with the handle. The shaft will rest between the two bushings, and should be free to rotate easily. At the end of the shaft we will use a mini BNC connector to attach any of the spoon heads. We have several attachments that can be used with the spoon: a deeper and wider spoon, a regular size spoon, and a spork.
Center of Mass:
In order for the spoon to operate as intended, the center of mass must stay below the axis of rotation of the spoon. The way we want to accomplish this is by having a composite shaft. The density of the top shaft is significantly less than the density of the bottom shaft. this will lower the average center of mass and allow the spoon to always be upright.
The spoon we designed has one degree of freedom. This mobility is caused by two bodies (the spoon head and the handle) being connected by a revolute joint. To ensure this joint doesn’t also act as a prismatic slider, there is an extra constraint in the back of the handle from the cap.
Assuming the offset center of gravity is negligible and no lubrication is applied, the rotation of the shaft was analyzed. For the shaft to rotate freely, the moment caused by gravity will need to be greater than 0.194 in*lbf. This calculation is very liberal so the friction in the system should not cause any issues for rotation of the shaft.
The fabrication process required the manufacturing of three different components that would then be assembled into a complete utensil. The first component was the handle of the spoon. Each handle was 3D printed from yellow PLA+ using a combination of Tennessee Tech’s printers and our project members’ personal printers. The second component was the shaft that goes into the handle of the spoon. This shaft was machined at Tennessee Tech out of 3/8″ Aluminum rods. We machined one end of the shaft and screwed the spoon head onto the machined surface. The final component is the bearings. These were assembled at both ends of the handle (press fitted onto the shaft). Front and back caps were also 3D printed to protect the bearings.