Abhinit Parelkar - UX/Interaction Designer

Embodied Interaction Project

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Smart Cart (Checkout System) - Embodied Interaction

Duration: Fall Quarter 2017

Role: Interaction Designer & Physical Prototype Developer

Cover Photo.jpg

Smart Cart

Say hello to the future of shopping.



Tangible Computing (as conducted, for example, by Hiroshi Ishii and colleagues at the MIT Media Lab), is an area of HCI research where people are exploring how we can move the interface “off the screen” and into the real world. In this model, we can interact with physical objects which have become augmented with computational abilities. This lets designers offer new sorts of metaphors, or take advantage of our physical skills (like being able to use two hands, or to rearrange space to suit our needs), or even to directly observe and respond to our physical activities in the world (perhaps by knowing where we are and who we’re with, and responding appropriately).
— Paul Dourish
A second trend is what I call “social computing,” which is the attempt to incorporate sociological understandings into interface design. This approach to HCI design recognises that the systems we use are embedded in systems of social meaning, fluid and negotiated between us and the other people around us. By incorporating understandings of how social practice emerges, we can build systems that fit more easily into the ways in which we work.
— Paul Dourish


An opportunity where the users (shoppers) don’t have to wait in the queue for the checkout/billing in-store.

Description & Reason:  A seamless approach to checkout in-store without the need to wait in the queue is a need, because no one likes waiting. Improving the efficiency by reducing the unnecessary efforts exerted by a patron is the main objective of an embodied solution for this need. A correspondence between a shopper and his/hers objectives can be maintained only if the meaningless inter-actions are made defunct.


To establish a correspondence between a system and its user by eradicating entanglements caused through transducers (in this case an interface/interaction).

The following were the detailed objectives:

  • Define a need.

  • Conduct design ethnography to establish a need & purpose.

  • Use one of the available analysis methods to understand the need.

  • Use one of the design method to visualize the design solution.

  • Come up with a 3D prototype.

  • Demonstrate embodiment of the prototype.

  • Conduct user testing.

  • Write a reflection.


I had a constraint of materials to build a physical prototype. On top of that the prototype construction phase had a very limited time. Therefore, I relied on craft materials to develop a static (to self-narrate the prototype functionalities while testing with users) 3D model.


Design Ethnography

I conducted a design ethnography by observing individuals purchasing goods and to checking out at the two super markets, "Pete's Super Market", and "Target Retail Store

Based on my observations, I came up with two excerpts for the two locations I visited. The one for the traditional check-out system at Pete's super market, and the other for the self-checkout system at Target. Design Ethnography helped me to step in to the users shoes. It validated the need to come up with an embodied design solution for the problem.

Analysis & Modeling Methods

Analysis Method: I used Affinity Diagram to identify recurring needs aspects & requirements.

Modeling Method: I used Mind Map to visualize the number of steps taken by a customer to accomplish his/her goals.

Modeling Method: I used Journey Map to visualize and analyze the user goals & pain points. For the optimal view of journey map: click here



Character: Emily is a graduate student living in a rented apartment. She frequently visits the retail market to shop her daily needs (which includes food items + healthcare products, etc.). She often takes her friend Rachel for shopping.

Scene: Emily visits a nearby supermarket for her daily needs. The supermarket is always crowded in the evening, which leads to the formation of a queue at the checkout counter. Emily finds evening as a suitable time to visit the nearby market. Waiting in the queue often makes her irascible. Emily reads a news about a grand opening of a new shopping market in the city which is well known for their smart shopping basket. Out of curiosity, she decides to visit the new shopping market with her friend Rachel.


Design Method: I used Storyboard to envision my embodied solution and its context of use. The narration used in the storyboard helped to remind me the purpose and the emotions behind the embodiment.


The prototype design (iteration one) was inspired from IDEO's process of innovation for the shopping cart concept in 1999.

The 3D prototype was followed by a sketching process.

The sketches helped me to ideate a shopping basket concept with the help of the following processes:

  • Illustrating several physical forms of a shopping basket,

  • Coming up with requirements & features for the concept,

  • Drawing the dimensional specifications (Includes an iteration with the help of the 3D model).

Materials used: Packaging boxes, construction paper, nuts & bolts, fine liner, pencil, colored pens, glue, packaging tape.


Demo 1: Gestural based basket handle interaction. Purpose: An accessible approach was required to control the basket's handle using gestures. The lift of one handle balances the lift of the opposite handle through its equilibrium mechanism.

Demo 2: Embodied Solution - Real-time Bill Calculation. Purpose: Users want to avoid waiting in the queue for the bill calculation. Incorporating bill calculation in the basket would avoid the formation of queue at the checkout. A checkout system without a need to wait.


I made a user testing floor map guideline. See Figure 1. This diagram would help the subjects to visualize the simulated environment of the in-store environment. 

I evaluated my prototype (Iteration 1) by conducting user tests with five participants. Each participant had to go through a series of tasks with the help of a floor map of a simulated environment.

The user tasks comprised of the following duties:

  1. Grabbing a smart basket - To understand the interaction of the user with the smart basket, especially the gesture-based interactions.

  2. Navigating toward the products area - Adding the items into the basket (shopping experience).

  3. Navigating toward the scanning area - To understand the transaction process after shopping the items (post shopping experience).

  4. Reading of instructions labels - To understand the customer’s preference (before leaving the store).

See Figure 1, 2, and 3.

At the end, participants were given an opportunity to talk about their experience and offer suggestions through an online survey.

The survey was focused on:

  1. Understanding their shopping experience through a comparison with a retail store’s checkout system. [open-ended question].

  2. Knowing their preferences about the need (standing in a queue at the checkout counter). [close-ended question].

  3. To acknowledge their experience with my embodied solution [open-ended question].

  4. To acknowledge their preference over the existing checkout systems (including my embodied solution) [close-ended question, open-ended question].

  5. Suggestions/demands of participants based on my embodied solution [open-ended question].

Results summary: The survey data justified a need to address the problem of “waiting in the queue at the check-out counter”. One of the participant found an additional benefit of the real-time bill calculation on the smart basket as a way to keep track of their budget. In addition, all the participants preferred “Smart Cart” as a checkout system due to it’s time-saving mechanism. On the other hand, participants found the gesture interaction confusing at the beginning. After a few successive trials they succeeded in learning gestures.


I had a tremendous pleasure in designing a solution for this need. A desire to go beyond screen-based, and click-based interaction was fulfilled through this project.

The metrics I registered:

  • Building a tangible artifact is not so easy as to build an app prototype on the computer.

  • Working on EI gave me an edge over web/app designers to think beyond the four quadrants of the display. It made me practice "design thinking".

  • The user testing revealed the fact that you are not your user. One of the participants found an additional advantage over the smart basket’s real-time bill calculator which helped him to manage his budget. This was a unique finding - an idea derived from user-centered design.

Did it go live?:

  • I'd love to see it go live. I need to iterate my design based on user testing data and come up with an interactive prototype v.2 (Arduino-based).

  • Incorporating inclusivity by diversifying the participants for user testing could lead to come up with a good design.



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