Abhinit Parelkar - UX/Interaction Designer


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Smart Cart (Checkout System) Embodied Interaction

Duration: Fall Quarter 2017

The problem:

Need: 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.

There’s a potential in the embodied solution to address this need. It’s always a displeasure and chaos to wait in the queue holding/maneuvering a shopping cart, which often makes a ruckus and blocks aisles in-store. In order to keep this under control, the company/store needs to allocate more employees to guide the ever increasing queue of the customers. In return, it doesn’t offer a good user experience nor does it profit the company/store.

Few retailers have come up with self-checkout systems, which doesn’t have any potential to replace service based checkouts, because the self-checkout systems doesn’t address the needs produced by a traditional checkout system (service-based). The self-checkout system still generates the queue, and requires human resources (employees) to manage the customer during checkout process. In other words, it’s just a different version of the previous model instead of an upgrade.

This in return converts a correspondence to an entanglement where the customer has to deal with the obstacles.


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.

The process:
Design Ethnography

I did a design ethnography to identify the need for the embodied solution.

Excerpt 1: 
Location: Pete's super market
Date & Time: Oct 18, 10:43 AM - 11:14 AM (Approx. thirty minutes)
Observation: I observed random customers in the wild using a traditional (service-based) checkout counter at Pete’s super market.
Note-taking: I jotted down thick descriptions and came up with the following sequence which elaborates the entanglements encountered by the customers:

  • The customer arrives at the checkout counter and waits in the queue.

  • Customers who are senior citizens usually takes more than average time to checkout. This agitates the customers standing in the queue.

  • The customers look around for the shorter queue in order to avoid the waiting. This indicates that the customers don’t like waiting and are always trying to save their time by avoiding longer queues.

  • Out of nine checkout counters, only three counters were in service in the morning. The customers could have avoided waiting in the queue and could’ve checked out through other counters, if it were equipped with self-checkout system.

Excerpt 2:
Location: Target
Date & Time: Oct 18, 5:50 PM - 6:15 PM (Approx. twenty-five minutes)
Observation: I observed random customers in the wild using a self-checkout system at Target.
Note-taking: I jotted down thick descriptions and came up with the following sequence which elaborates the entanglements encountered by the customers:

  • The customer arrives at the self-checkout system.

  • Encounters an issue with the scanning of the item.

  • The customer gives an indication of help.

  • The employee 1 arrives approaches the customer to help.

  • The employee 1 seems not have not figured out the issue, hence calls the senior employee.

  • The senior employee interacts with the POS and takes away the two items from the customer.

  • The customer waits for the employee to return the two items. (I was at a distant, therefore couldn’t figure out the query or the issue the customer had).

  • In the meanwhile the senior employee returned back with the two items and returned to the customer.

  • The employee interacted with the POS of the self-checkout system and walks away.

  • The customer scans the leftover items from the shopping basket.

  • Chooses card payment option and completes transaction.

  • The customer collects the receipt and walks out.


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


Storyboarding (using Freytag's Pyramid structure)

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. She decides to visit the new shopping market with her friend Rachel.


Design Method: I used Storyboard to visualize how my embodied solution might fit in the user journey. The narration used in the storyboard would help me to set up a user testing environment with respect to the set of assigned tasks to a subject.

Making Exploration

Before starting with a prototyping process for a three-dimensional object, I was compelled to explore different sensory feedback loops by creating a geometric or other shape using different media. To find the process: click here



The prototype design (iteration one) was inspired from IDEO's process for 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 forms of a shopping basket,

  • Coming up with requirements & needs 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. Need: Accessible approach was required to lift 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. Need: Users want to avoid waiting in the queue for the bill calculation. Incorporating bill calculation in the basket would avoid the queue at the checkout. A checkout system without a need to stop (keep walking).


User Testing

I made a user testing floor map guideline. See Image 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 “Simply checkout” 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.


The Smart cart (Simply Checkout) prototype evaluation revealed certain facts about participant’s aversion toward present in-store checkout systems. 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 reveals that there’s a possibility where a customer could interpret or make use of the product/service in a different way than what a designer originally thought of. The evaluation methods fulfill human-centered design approach for making products adapt to their users. Suggestions from the participant’s data through prototype evaluation helped me to consider certain drawbacks which were overlooked during the prototyping phase.

The limitation of the prototype construction resources and the complexity of the prototype led me to build a smart basket instead of the smart cart. The participant demographic lacked the diversity and the sample size was limited (only five). The future work will incorporate the evaluated data (from the first round of user testing) in the development of the prototype (Iteration 2).



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