2024 ASEE Annual Conference & Exposition

Prototyping is a key aspect of engineering design. A prototyping strategy describes the process and methods used to accomplish the prototyping process. Many variables comprise a prototyping strategy including how many different concepts will be prototyped in parallel, will the prototypes be scaled, what manufacturing techniques will be used to create the prototypes, how many iterations in a model will be needed, what design requirements are being evaluated by each model, will subsystems be prototyped separately and will digital or physical prototypes be used (or both). Engineering design teams often follow the same prototyping strategy used in their previous design efforts. However, research shows that this is not always the best decision. Careful consideration of the prototyping strategy, based on specific characteristics of a design project, can lead to significant benefits for the outcome of the design.

This current work provides a method for assisting an engineering design team regarding decisions on when to use digital and/or physical prototypes. Physical prototyping, in this context, refers to any physical embodiment of the product or system. Digital prototypes in the current context are any digital representation of the product or system including CAD and/or digital simulations. The decision regarding use of physical and/or digital prototyping needs to be evaluated not only for the entire product or system being designed, but often for each subsystem. With the increasing use of additive manufacturing to create physical prototypes, combined with the ever-increasing capabilities and availability of digital prototyping capabilities, the decision of when to use digital vs. physical prototypes is an evolving target.

The development of the current strategy for evaluating decisions on digital vs. physical prototyping came as a result of an extensive interview process with numerous engineering design teams. These interviews were used to evaluate the ways that the design teams made prototyping decisions and then used this information to create a prototyping strategy or process. A weighted design matrix approach is used to assist the design team regarding digital/physical options. This is done for the entire product or system and also for key subsystems.

This current work specifically correlates aspects of cost, schedule and performance with advantages for either digital or physical prototyping. The category of performance is divided into two subcategories of “performance best assessed by” and “model delights the stakeholder”. This division will be described in detail in the paper. The left part of the matrix contains this initial portion of the method.

A second part of the method adds the aspect of flexibility of the cost, schedule and performance as a refinement of the matrix output. Finally, aspects of the organization’s capabilities in terms of resources and team skills specifically associated with either digital or physical prototyping are incorporated. These refined aspects are incorporated into the right portion of the matrix.

To assess the method, the matrix approach is applied to two engineering design projects, one involving the design of a remote-controlled car used as part of an educational experience and a second project focused on development of a video game controller. For each project, cost, schedule and performance are used as evaluation criteria mapped against digital or physical prototyping impact. The design teams found the method relatively easy to understand and use. The results of the implementation of the weighted design matrix is a set of suggestions for digital vs. physical prototyping options for both individual subsystems and for the entire product/system. The design teams found the numerically based suggestions and associated bar graphs to be very helpful in planning their prototyping strategy. In one case, the matrix output completely changed the way the designer decided to prototype their design.

In addition, a team of scientists and engineers at the Air Force Research lab were asked to provide feedback on the method. Feedback from this group of practicing engineers was very positive. They specifically commented that the incorporation of cost, schedule and performance was intuitive as these three aspects are critical to monitor for project success. They also indicated that the bar graphs associated with the matrix outputs were helpful in providing overall insight into the prototyping decisions. More details on the specific assessment is provided in the paper.