# Development of Low-Fidelity Virtual Replicas of Products for Usability Testing
## 1 Introduction  
Formative usability testing is the process of evaluating a new product with its users to gain information about potential use errors and places for design improvement [1; 2; 3]. For this type of testing, designers make strategic decisions on what aspects of the design will be evaluated (e.g., the functionality of the device, instructions), recruit subjects from the target user population, and have them use the device in a simulation of its use environment, record the performance, and analyze the results [4]. Designers can improve the look and functionality of their products by performing this type of usability testing iteratively and early in the product development process [5; 6].  
The prototypes used in formative usability testing are placed in two categories: high-fidelity and low-fidelity. These prototypes approximate the functionality and look of the final product [6; 7; 8]. High-fidelity prototypes have the same level of functionality and are made with the same production method and materials as the final product [7]. On the other hand, low-fidelity prototypes are low-tech or low-quality (e.g., made of paper or cardboard, static images on a screen) and only cover partial aspects of the final product functionality [7; 9]. These models are created at distinct stages of the design process. High-fidelity prototypes are typically made towards the end of the design process due to their cost to produce. Low-fidelity prototypes are used early in the design process of a product, but the lack of full functionality makes it challenging to identify use errors in formative usability tests, which indicates failures during user-product interaction [10; 11]. Due to their limited functionality, it is challenging to recognize use errors in low-fidelity prototypes,which restricts the ability to identify significant issues in the early stages of design. One method to overcome these issues is to design these prototypes to be assessed in a virtual environment. Performing tests in a virtual environment helps to save on the cost of building physical prototypes and allows for earlier testing with fewer resources [6; 12; 13]. In addition, virtual prototypes can be used to pilot the software architecture very early and reduce the chance of mismatch in user expectations by organizing the required product functions that must be replicated within the simulation.  
Advancements in computer-aided design (CAD) technology provide potential for the device to be used to assess usability, but the software has limitations. Currently CAD models are used to assist with design review [14; 15; 16; 17; 18], create virtual replicas of the final product and associated inform design documentation [19; 20], communicate design ideas [21; 22], and perform simulations on device assembly [23; 24; 25]. These uses involve minimal to no interaction with the models by the potential users, therefore usability cannot be evaluated. CAD models must be exported to other programs, such as a game development engine, where detailed interactions are added. In addition to object interactions, the CAD model could be placed in a virtual environment to replicate where the product will be used in the real world.  
This paper will discuss a process used to create a low-fidelity usability test utilizing a CAD model. Enhanced use of CAD model in usability tests will expand capabilities to evaluate user experience and refine the design based on feedback, thereby reducing the potential for mismatch between user and designer expectations [26].