Senior Design Project

Project Description

The goal of this project was to simulate the development of a new product in a four person design team. The market opportunity was mobility assistance for an aging population. Our team needed to identify opportunities where machines could support or enhance the mobility of an aging population and then design and develop a prototype which addresses the opportunity identified. We were tasked to not only solve a design problem, but also define what that problem was. We developed a concept called the spring up that allowed seniors to get out of a chair easier.

Budget: $450

Approach

Research

Overall Research Process

The project began by conducting research into our chosen market opportunity. Our group accomplished this by each going out on our own to observe, interact with, and interview the aging population or those who work with them. We conducted interviews with our grandparents, physical therapists, nurses, and nuns. We also made observations at airports, churches, bowling alleys, senior volleyball games, and grocery stores. Gathering as a group at a local pancake house also helped us to make observations, discuss what we were seeing, and look at how it compared to what we saw individually.
After gathering the information through these observations and interviews, we transformed it into readable quotes or observations with post it notes. We grouped all the similar items together and then grouped them again into more specific categories. This allowed us to visualize what the common issues were among the aging population. Pictures of this process are shown below.

Insights from Market Research

The main insights we gained were turned into design directives that could be grouped into three main guiding principles which were used to develop product concept ideas.

Concept Selection

Using our guiding principles, we individually developed concepts totaling around 100. An example of some concepts and sketches are shown below. We each chose our 4 best ideas and examined the strengths and weaknesses of the concepts. Voting rounds then took place after we presented our concepts to the group. We ended up with three final competing concepts. Discussions about feasibility, how well each design met our guiding principles, budget, and the timeline were made to determine that a design that enables seniors to get out of the chair easier was our best option.

Initial Concept Sketch Example

 

After determining which problem we wanted to solve, we completed benchmarking and trade studies that enabled us to research the possible mechanisms we could use to lift a seat cushion. These trade studies primarily focused on selecting a motorized lead screw mechanism vs. a mechanical spring option. Due to weight, budget, and size constraints the mechanical spring option was chosen along with a link mechanism. This was chosen because we aimed our design towards portability and trust of the user. Our preliminary research told us that seniors trusted their mechanical devices for their reliability such as a walker vs. an electric chair. A pre-prototype made from a pizza box and hot wheels cars was used to get a feel of the design challenges we would need to solve.

First Prototype

We then needed to determine which type of spring to use, a mechanical spring or a gas spring. Building a better prototype allowed us to compare the feel of each design. A calculation of the torque for each design showed a linear relationship for the gas spring vs. a parabolic torque for the mechanical spring. This is due to the constant force of the gas spring vs. the variable force of a mechanical spring. You could feel this difference on the prototypes. The gas spring provided a kick towards the end of seat rotation and the mechanical spring felt much smoother during the whole seat rotation. The mechanical spring was chosen due to this smooth motion vs. the kick at the end of the gas spring when the torque was a maximum. We did not want to throw the seniors to the ground with our spring up mechanism.

Gas Spring Prototype

Design

Designing our final working prototype was done in CAD first and then built in the machine shop. Our final design is shown below along with a video demonstration. FEA, link length calculations, mechanism comparisons, and cushion comfort benchmarking were all completed to aid in our final design material selection and configuration.

Final Working Prototype

Results

We successfully created a working prototype from research to the design phase. We determined more improvements would need to be made before any commercialization, but we were able to test our product with one of our initial interviewees. Sister Bernice had trouble sitting down on the spring up because it was designed for a 5’7” height, 150 lb person, but she enjoyed how much easier it was to stand up. This positive experience made the design process worth it. We were happy to see we made a prototype that could be used to gain real customer feedback that would be used for future design iterations.