Redesigned vending machine selection for maximum efficiency within the predetermined context of a parking garage.
Interaction Design Studio, Carnegie Mellon University, Spring 2020
Design a physical or digital control for an assigned context that has distinct input and resulting outcome. The input can be manual or automatic, and the output might be an associated action or display of information.
Interaction design, physical prototyping, project documentation
Adobe InDesign, Adobe Photoshop, Adobe Illustrator, physical modeling materials
Context Exploration
The assigned context I received for this project was a parking garage. I don't own a car, but Carnegie Mellon's campus has a garage in close proximity to the School of Design. I began with a walk through the garage, identifying as many interactions as I could and narrowing down to five, on which I focused an in-depth interaction inventory. 
Broad Sketching
As I decided on a single control for redesign, I returned to the garage to gather additional details. I noticed a vending machine against the wall. Issues with vending machine selection immediately came to mind that might be addressed through a redesigned control. I was encouraged to explore design and usability principles in my sketches, especially discoverability and using the overlooked.
This lead me to heavily consider how the front of the vending machine, which is often static and flat, could be incorporated into the final interaction.
The more I considered the nuances of a new selection control, however, the more questions I found there were to address: If users can select and then pay, or pay and then select, how should the prototype reflect these two flows? Should I also prototype the payment mechanism? Could sound feedback and button proximity lead to a vending machine accessible to visually impaired individuals? Is prototyping for multiple snack unethical, given it might encourage overeating?
Early Prototyping
I first prototyped a button that would only partially depress if credit was not available to pay for the item, and whose proximity to an item would afford the placement of a Braille label next to each. Further critique confirmed what I already suspected: I still needed a stronger angle through which to filter my considerations.
​​​​​​​Contextual Considerations
Refocusing on designing for vending machines within the context of a parking garage quickly prompted a moment of clarity. People typically only go to parking garages out of necessity—and no one wants to be in a parking garage for longer than they need to be! If a vending machine is designed for this context with one guiding principle in mind, it should be efficiency
Aligning my perspective to the efficiency of the control allowed me to make informed and constrained decisions about the ideas I'd brainstormed.
For example, the efficiency of selection would be driven by its proximity to the item itself. The user would push on a snack compartment to select a snack, and it would rotate open horizontally to allow for nearly immediate retrieval (as opposed to waiting for the item to vend and refill).
Additionally, a clear compartment for the snack would allow users to see right away whether a compartment was empty. Lighted panels around each compartment would combine mental models of red ("stop") and green ("go") with clarifying icons to signal snack readiness to users.
Planning for State Changes
Having narrowed the concept, I set about identifying the phases of selection to account for, and determining signifiers and feedback for each with efficiency in mind. The following diagram is an excerpt from the process documentation I created for the project showing the qualities of each state.
Physical Prototyping
I decided to create my prototype out of black foam core to contrast with the electric light and brightly colored snacks. My first step was to sketch the measurements of the individual pieces I would need to build a box with a protruding, open platform for the revolving door.
In order to replicate the look of electric lights for each state change during my classroom presentation, I used my phone's bright flashlight to light the snack compartment, and my bicycle's brighter headlight to backlight the buttons.
I then used Photoshop to overlay images and create a clean picture of each state. 

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