ERGONOMIC KEY
Tools and Skills: Ergonomic Analysis, Anthropometrics, Concept Sketching, Rapid Prototyping, User Testing, CAD in Fusion 360
Project Brief
In this group project, we were tasked with redesigning a common hand tool. Using ergonomic analysis, rapid prototyping, and user testing, the new design should eliminate friction points that users often experience when using the tool. The ultimate deliverable was a CAD design of the tool in Fusion 360.
Challenges
We wanted our final product to be realistic, and since keys are so standardized, we didn’t see success in modifying the design of the key itself. Our main challenge then became an ergonomic attachment for the key that provides more control, alleviates pressure points, and is convenient to carry around.
Results
Since we chose a rather unconventional subject for this project, we ran into a lot of obstacles that our teaching team didn’t expect. We successfully navigated these hurdles by communicating well and frequently, narrowing down our user group, and prioritizing feedback from user testing.
HAND TOOL SELECTION & FRICTION POINTS
While a key isn’t often considered a “hand tool,” we thought that it would be an interesting item to explore — even though keys are possessed by almost everyone, they are not the most convenient to use. Particularly, the small surface area of the head puts significant pressure on the fingers, and the full wrist rotation required to turn the key causes stress and contortion. One of our group members actually has arthritis in his fingers, so he experiences these friction points daily. We ultimately decided that our target user group would be people with arthritic fingers and/or limited hand dexterity.
BIOMECHANICAL CONSIDERATIONS
The two main motions we wanted to consider for our “redesign” were inserting a key into a lock and turning the key. Since keys are so standardized and our target user group is a subset of the key-using population, we thought that it would be impractical to redesign the key itself. As a result, we decided to design an attachment for the key head that would allow the user to take a less precise grip. A wider key head would reduce pressure on the thumb and pointer finger and would create more torque, reducing strain on the wrist.
Some nice-to-haves we wanted to consider incorporating were for the attachment to be able to hold multiple keys, to be easily portable and not too clunky, and to indicate the correct orientation for inserting the key into the lock.
DESIGN EXPLORATION
In this first phase of design exploration, no idea was a bad idea. We wanted to consider as many different shapes, sizes, grips, and mechanisms as possible.
RAPID PROTOTYPES
We each picked two concepts from our design exploration to prototype out of pink foam, which is ideal for carving out 3D shapes. We also laser cut some generic keys so that we had a better idea of how the prototypes would function. I wanted to prototype an idea that had real potential (the Triangle Key Hat) and an idea that was unrealistic but could lead to interesting findings (Domed Key Box).
USER TESTING & FEEDBACK
We then moved to the user testing phase. We had the users fill out the hand pain model to the right to record where the biggest pain points were while using our prototypes. In order to simulate limited hand dexterity, we were provided these Cambridge Simulation gloves, which restrict finger movement. Below are some of our findings:
Domed Key Box: while the large dome shape was easier to hold than a small key, it forced the user to stretch their fingers out over an uncomfortable distance and wasn’t the most intuitive to use.
Door Handle Attachment: this prototype was successful since allowed the wrist to be at a neutral angle and provided more grip area. The only concern brought up was that it would feel too clunky to carry around.
Retractable USB Model: users liked that this concept was small, would protect them from getting poked by the key, and provided a more grip area and torque. While it still produced some pain points, it was most enjoyed.
DESIGN CONCENTRATION
Our testing phase revealed that the Retractable USB Model was the most successful, such that it was small, covered the key blade, and provided more grip area. In narrowing down our concept, we wanted to consider the two main features of this model: key coverage, or how much of the actual key the attachment would envelop, and motion, or how much the user would have to move the key in order to use it.
We used the design concentration matrix to the right to combine these two factors over spectrums: going down, the amount of key coverage increases, and the three movement mechanisms we considered were none at all, a push and lock mechanism, and a pen-clicker/spring-loaded mechanism.
We then each selected one of the ideas, sketched it, and prototyped it with pink foam. The concept I prototyped was the “Mid-Length Box Cutter,” which was retractable and covered about half of the key blade. This test revealed that we would have to consider the distance the user would have to stretch their thumb in order to fully expose the blade.
FINAL CONCEPT
While covering the whole key would have been ideal, we found that the distance along which the user would have to stretch their thumb to fully expose the blade would be uncomfortable. We determined that covering around 3/4 of the key struck a nice balance between sufficient key coverage while limiting thumb stretch distance.
Our final deliverable was a CAD mockup, which can be seen below. I envisioned that the body would be plastic and would have colored, rubber indicators to show where the user should hold it and to provide more grip friction. If we had time to further this project, it would have been interesting to physically build a functional final product, since some points, such as how the user would insert and secure their key in the device, remained unclear.
