Implementation of conceptual validation of product mock ups with augmented reality

The implementation of computational aids in product design is a demand in the design processes on century XXI, that because they allow an increase in quality and creativity of the deliverables of a design process. But this implementation should be guided to an academic process, where technologies methodologies work along. This article presents the results of an implementation of virtual reality techniques to validate and increased product design courses within the undergraduate electrical mobility in Product Design Engineering at that university.


I. Introduction
Computer tools are used to facilitate the human tasks, therefore, also to facilitate the product design processes by offering designers to spend more time in creativity rather than detail (Robertson & Radclife, 2009), moreover, the implementation of different computer tools in design processes have increased the success rate of the new up to 60% (Valle & Vazquez-Bustelo, 2009).
Considering all the impact that the implementation of computer tools had over design processes, there is important to identify the different computer tools that can be implemented on each stage on a product design.
In this connection, computer tools can be described by their usage in product life cycle (Product life cycle: Need, design, manufacture, distribution, usage and disposal (Kusiak, 1993)) in two different classes.Those that can be used through all design stages, that are called collaborative-work support tools and those that are used on specific design stages, that are called functional tools (Osorio-Gómez, Mejía-Gutiérrez & Ríos-Zapata, 2012).
Collaborative-work support tools are used to empower collaborative and distributed work based on concurrent engineering principles (principles described on Concurrent engineering fundamentals-Integrated product and process organization [Prasad 1996]), and three types can be described: communication tools, project management tools and information management tools (Osorio-Gómez et al., 2012).
Functional tools have the characteristic to be used to solve specific tasks inside the product design process, and are divided into four categories: analysis tools, modeling tools, representation tools and simulation tools (Osorio-Gómez et al., 2012).
This article presents the implementation of functional computer tools into the validation of product mock-ups by the implementation of augmented and virtual reality simulation techniques on product design projects in electric mobility taught at Universidad EAFIT in the undergraduate program of Product Design Engineering.

II. Methods and materials A) Context
In Product design engineering, several design methodologies are wrapped on electrical mobility courses, including those that are by far the most known in education and industry (Tomiyama, Gu, Jin, Lutters, Kind & Kimura, 2009), like Pahl and Beitz that can be summarized in four steps: Planning and clarification of the task, conceptual design, embodiment design and detail design (Pahl, Beitz, Feldhusen & Gote, 2007); others important methodologies that made part of PDE methodologies are Baxter (which is described in six steps: business opportunity, design specifications, concept design, embodiment design, detail design and design for manufacture (Baxter, 1995) and Ulrich and Eppinger, that has six steps, one of them, focused in testing and validations of products (product planning, concept development, system level design, detail design, testing and refinement and production ramp-up (Ulrich & Eppinger, 2004).
Based on these methodologies, a design methodology was adapted for electrical mobility courses.This methodology can be watched on Figure 1.It important to recall that electrical mobility course is a year course that is composed by different two different courses, Project 7 and Project 8.At the end of Project 7, students must deliver a mock-up of their designed electrical product; these mock up is then validated through use of virtual and augmented reality techniques.
Validation tests during the product design and development process are conducted at different stages and guarantee the functionality and acceptance of the proposed solutions in advance of its industrialization process reducing time and costs and improving the final quality of the result.Such validation is carried out through the implementation of different kind of prototypes, such as physical prototypes, virtual prototypes or abstract prototypes (Horvath, 2011).In the current design engineering practice, at both academic and industrial level, prototypes are usually created as physical or virtual prototypes; and each one includes a different level of information related to the design parameters of the solution.Virtual prototypes are often adopted to realize the geometry and the structural composition of the product and they are used in simulation or visualization tasks, but the human-product interaction is restricted to the computer interface.In the other hand, physical prototypes are implemented at different stages of the design process according to their level of elaboration, but they are a little flexible and their quality and functionality is time and cost dependent.Simple and non-functional physical prototypes are useful for preliminary validations in the initial phases of the process and detailed and functional physical prototypes are useful to evaluate functionality, aesthetic aspects (such as shape, textures and colours) and physical aspects (such as weight) at later stages of design.
Anyway, the virtual reality (VR) application with its immersive environments and intuitive interfaces allows a better validation of the products and the experience gets better when the number of involved human senses increases.This is directly related to the cost of hardware and software and neither real components nor environments are considered.
At this point, the augmented reality (AR) application is useful to integrate physical and virtual prototypes allowing their interaction and yielding information in real time for design validation, at lower costs than VR and in a much simpler manner.A description of different uses of AR at different stages of the product development process could be observed at (Uva, Fiorentino & Monno, 2011) where the authors present different technical considerations according to the product development scenarios and applications.Here it is worth noticing the level of required knowledge related to computer graphics and animation.
Therefore, considering that Product Design Engineering students are not related to this kind of visualization and representation tools and their programming skills are not well developed during their academic background, at the last semesters of the curriculum during the one-year lasting project they are introduced to a basic AR experience in order to allow them evaluating their proposed solutions after the conceptual solution definition, integrating the virtual model of the proposed product along with a physical non-functional mock up.

B) Augmented reality implementation
Across the Project 7 course, students must do a preliminary 3D model of the electric product they are designing.Parallel to the construction of a 1:1 scale mock-up, they must start with pre-work in order to validate their model using virtual and augmented reality.These are the steps that must be followed in the pre-work: » Develop the 3D model of their product.
» Identify in their model the places where augmented reality markers are going to be located.For so, students must consider the critical views on their model, those where more detail is needed.» To each critical spot identified, assign a coordinate system.To each system must be associated the relative translations and rotations from global coordinate system.Defined the places where augmented reality markers are located, then a multi-marker set up must be build.Each marker must follow the structure shown on Figure 2: » Line 1: Marker number » Line 2: Path of the marker » Line 3: Marker width » Line 4: Offset on X-Y of marker coordinate system » Line 5-7: Rotational and translational matrix of marker coordinate system against global coordinate system.
Finally, the structure of rotational and translational matrix can be appreciated on Equation 1, where R is related to rotation and T to translation on the three axes.Equation 2shows the equivalent rotations matrix for the three axes.The pre-work of the validation finish with the construction of the mock-up and the location of the markers on the product.An example of a markers location on mock up can be watched on Figure 3.

A) Project 7 and augmented reality validations
At the end of the Project 7, students must present their mock up set up for virtual and augmented reality validation.This is done on a public showcase made at the last week of semester.Figure 4 shows mock ups presented on the showcase.
In order to facilitate the validation it was developed a product (VR/AR glasses) that allows creating an immersive environment that supports the validation of the products through virtual and augmented reality.This product was built in the research group of product design (GRID) of Universidad EAFIT.On Figure 5 it can be appreciated the experience during the showcase, which included teachers, judges, students and parents as well.Finally Figure 6 shows how the virtual environment fit the real environment by the use of the VR/AR glasses during the final show case.

B. Project 8 and results of augmented reality validation
On Figure 6 it can be watched on concept that was previously validated by the use of virtual and augmented reality, finally on Figure 7 the final result of the electrical mobility project can be watched.Then it can be watched the final result of the project shown on Figure 3 and bottom of Figure 7.

Discussion
The implementation of augmented and virtual reality techniques had improved the experience of product design students in terms of validation of aesthetics, proportions, functional and ergonomics aspects of their products.Even if these VR/AR validations had started on 2011, they had already shown high impact in how the Product Design Engineer Students design, and these tools had begun to break the paradigm.
Most of the influence is related that students can validate different design alternatives without investing time and money by building functional mock ups.On academics, this has represented a positive change, because students are more confident to design products in higher level of complexity, this, because the VR/ AR validation acts as a milestone in the design of the project, and many of the trials done in the immersive environment result as an important feedback within the detail design stage, which is the first part of Project 8, when the final functional model must be designed and build.
Moreover, since Product Design Engineering Students have already experience in working with virtual or augmented reality, they feel free to work with this technologies not only as mandatory activity on Project 7, but some students are already implementing these simulations in their final undergraduate projects and subjects in postgraduate courses.
Finally, the implementation of these simulations had the higher impact in how ergonomics is being validated; even if Computer Aided Drawing tools had ergonomics modules, the validation done in the immersive environments during the final showcase had become one of the most significant source of feedback taken by the students for being considered on next design stages.