Ergonomics, Usability and Virtual Reality: a review

applied to consumer product

Christianne Soares Falcão, Marcelo Marcio Soares Federal University of Pernambuco

Recife, Pernambuco, Brazil christiannevas@hotmail.com

ABSTRACT

While it is recognized that introducing products that meet the needs of recent consumption is important, what is crucial to the success of the final product is to evaluate its usability during the early stages of the design process. Currently there are few analytical tools that can foster better support to the entire process of product design. Virtual Reality has emerged as a useful aspect of new technology that gives efficient and effective support to the design of products. Therefore, this article presents a conceptual approach to usability and its relationship with Ergonomics, and points to the importance of using Virtual Reality throughout the product development life-cycle as its use offers a more efficient approach to usability.

Keywords: Usability of consumer product, Product Design Development

Process, Virtual Reality

1 INTRODUCTION

Users of consumer products have benefited from companies’ growing interest in seeking technological innovation to improve their competitiveness and business performance. Industry is constantly looking for new and better products that have satisfactory sales in the market. To this end, there is a need to invest in innovative products bearing in mind that globalization makes a vast range of new products and

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features available, this has led to more demanding consumers and increased market competitiveness.

In order to introduce products that are compatible with current market requirements and needs, the designer should take into account product users' best needs in terms of usability and of what gives them pleasure, what appeals to their emotions, and to demonstrate that the product is safe and tailor-made for them (Seva et al, 2011). Keeping the user interested in the product requires competence from designers and ergonomists at the interface who have invested in streamlining the design process so as to manage knowledge, skills and the stock of technologies.

At the same time, according to Mahdjoub et al (2010), during the design process, engineers underestimate such factors as Ergonomics. As a r esult, many products around us have not been conceived to meet end-users’ expectations, including the need for them to be usable. For this and many other design factors, companies have invested heavily in usability and user experience testing labs to test their products before their release to the market.

Starting with the concept of complexity which is attributed to the technology of products, Ergonomics and usability have come to play an important role in developing products that better match users’ wants and needs. Usability is about the product ease of use so it is necessary first and foremost to know who is the user/ consumer, their needs and requirements so as to serve them efficiently. Human Factors & Ergonomics, in these circumstances, presents itself as an essential discipline when analyzing the interface between the product and the user.

When evaluating products, there is a need for evaluating product through several stages during the design process to ensure the final product is successful. However, many assessment tools are limited as they do not provide the means for detecting problems that may occur in real world usage because laboratory tests are only simulated use cases of the product. Therefore, extensive research is needed to investigate the efficiency and effectiveness of assessment tools based on up-to-date advanced computer technologies in order to provide better support for product design throughout the development process (Ye et al, 2007).

To meet this need, virtual reality (VR) has emerged as an option to reconcile the advantages of field and laboratory studies because it enables the user to interact with the product in a context similar to the real situation while allowing the researcher to have full control over the variables and safety conditions (Rebelo et al, 2011). Besides this advantage, VR can easily be included in participatory design methodology as VT displays design solutions effectively (Reich et al, 1996).

Thus, studies show VR as a potential tool for the design of human-centered products, especially when it is integrated with Ergonomics. However, Mahdjoub et al (2010), point out the need to integrate these technologies with a designer’s knowledge in order to be more efficient in promoting the usability of the product even at the early stages of the design process.

Driven by this challenging statement, this article gives an overview of applying VR technology to evaluate the usability of consumer products. The first section sets out the theoretical concept that underpins the study and describes usability and its correlation with Ergonomics. The second section explains the concepts of virtual

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reality and their application in product design, and does so in order to provide the basic information needed to understand its advantages and how this is integrated with the Product Design Development Process.

The purpose of addressing this theme is to underpin a research study that sets out to investigate the appropriateness of using virtual reality technology in assessing the usability of consumer products, by making a comparative analysis of virtual prototypes and the real product. The intention is to use the results of the analysis to set parameters for exploiting VR in product design.

2 USABILITY

Usability is well-known and well-defined as to the approach of Human-Computer Interaction (HCI), the concepts of which are applied to enhance the software-user interface (Nielsen, 1993). Basing themselves on these concepts, many studies seek to apply them to fostering usability in consumer products (Jordan, 1997; Logan, 1994, Han et al, 2001).

Starting from an informal concept, usability was originally defined as the ability of a product or system to be used in an effective, efficient and enjoyable way by a specific range of users for tasks that need specific tools within a given environment. ISO 9241-11 (International Standard Organization, 2006) sets out the most classic and recognized concept of usability, "the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use ".

Effectiveness refers to the extent to which an objective or task is reached. Effectiveness measures the relationship between the results obtained and the desired goals, i.e. to be effective is to manage to achieve a given objective.

Efficiency refers to the amount of effort required to achieve an objective. The lower stress, the higher the efficiency.

Satisfaction refers to the level of comfort that the user feels when using a product and to what extent the product is acceptable to the user in relation to achieving his/ her objectives. As it is more closely linked to subjective factors, this aspect can be more difficult to measure than effectiveness and efficiency (Jordan, 1998).

Krug (2000), characterizes usability from a simple perspective, as the certainty that something works well, and that a person with average (or even below average) skill and experience can use something that it is intended he/she should use, whether it is a website, a hunter jet or a revolving door, without getting irretrievably frustrated.

Based on the definitions of usability presented, and other contexts not covered, it can be observed that they share the following issues:

· There is a user; · who owns an activity; · using a product or system.

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According to Tullis & Albert (2008), usability can have a huge impact on

society, regarding access to goods and services for different user populations, such as the elderly, people with disabilities or those with language or literacy difficulties. Usability impacts everyone, every day, and crosses cultures, gender, age and economic class.

For Santos and Maciel (2010), usability is gradually being incorporated into product development and is no l onger being seen as a separate activity. If a participatory design process is used, usability methods bring designers closer to users by providing a better match of products to the real user needs.

2.1 Ergonomics and Usability

Ergonomics can be understood as a discipline focused on the nature of the interactions of humans with artifacts, which starts from a unified perspective of science, engineering, design, technology and management of human-system compatibility, including a variety of products, processes, and natural and artificial environments (Karwowski, 2005). Ergonomics deals with a wide range of problems relevant to design when evaluating work systems, consumer products and workplaces, in which human-machine interactions affect human performance and the usability of products. According to Karwowski, S oares and Stanton (2011), ergonomics uses a holistic approach, centred on the user, which considers within its range of action physical, cognitive, social, organizational, environmental and other relevant factors, using appropriate methodologies, to improve design. Thus, Ergonomics is involved in the various decision-making stages when a product is being developed which leads to its having a key role in improving the performance of products.

In this context, usability becomes part of Ergonomics so that products and systems may be adjusted to the user, taking into account his/ her needs, abilities and limitations. It presents itself as the border area between the user and the parts of the system with which the user is interacting. At this threshold, Ergonomics and usability contribute perform this objective in order to maximize user satisfaction.

2.2 Attributes of usability

When analyzing usability, some principles of product design should be observed in order to avoid mistakes and difficulties in using the product. If each of these principles are complied with and if the design is for a defined and identified target audience, it will probably be possible to maintain good product usability and highest user satisfaction. Jordan (1998) lays down ten principles of usability and describes why and how each affects usability:

· Consistency - Similar functions and tasks are performed similarly. · Compatibility - The conduct of a task using a given product is compatible

with the user's expectations, based on other similar products.

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· Considerations of user resources – These are seen to have been included when the conduct of a task takes into account the demand on the user’s available physical and mental resources.

· Feedback – This takes place when a product has a significant response to the actions taken by users in performing a task and these are received and acknowledged.

· Error prevention and recovery - when performing a task, the possibility of error is minimized and should the error occur, it can be quickly and easily corrected.

· User control - where the user has control over the actions taken within the task without the overall process being automated.

· Visual clarity – when the layout of information can be easily read and interpreted without causing confusion or misinterpretation when the task is being performed.

· Prioritization of functionality and information - when the most important functions and information in the tasks can be very easily viewed and accessed by the user.

· Appropriate transfer of technology - when a technology developed to perform a cer tain task or for a cer tain product is correctly transferred to another context by appropriately performing a different task.

· Explicitness - where a product’s functionality and method of use are explicit.

Norman (2006) defines two principles of design that are fundamental for usability: providing a good conceptual model and making things visible.

Nielsen (1993) stresses that usability is not a unique, one-dimensional property of an interface but rather it has multiple components and is traditionally associated with five attributes: Learnability, Efficiency, Memorability, Errors and Satisfaction.

Rebelo et al (2011) propose a division of the attributes of usability of products into those that are objective and those that are subjective. The objective attributes of usability include: effectiveness, learnability, flexibility, understandability, memorability, and reliability. A subjective attribute of usability includes the attractiveness of the product, which affects the positive attitude toward the product.

Such usability criteria should be studied systematically, using a well-developed design with well-established steps. The discipline of Usability Engineering was created as a result of this need. It sets out to conduct in a s ystematic way the activities needed to draft the interface throughout the life cycle of product or system development (Nielsen, 1993).

Thus, the designer determines which attributes are key components of the product for usability, and he/ she should define what each one really means for the product and how this will be measured by using usability methods to find out how each characteristic of usability can be measured.

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3 VIRTUAL REALITY

During product design process, design team need to have the ability to think creatively about alternative design paths and to make decisions based on product use simulations. Meeting such needs has been getting better due to technological developments. From the second half of last century, tools that help to build up our capacity for simulation have been under development. These are the technologies in Virtual Reality (VR).

Virtual Reality technology is capable of providing an immersive work environment. By using various peripheral devices such as motion capture systems and haptic interfaces, different ways for interaction between the user and the VR system are supplied. Buck (1998) used VR technology and DHM (Digital Human Modeling) tools to enable people to take part in the design of the industrial system. VR has also been used in ergonomic applications to evaluate different aspects of the operations of human movement (Whitman et al, 2004; Jayaram et al, 2006; Wang et al, 2007).

Under a broader definition, virtual reality is one way to transport a person to a reality that is not physically present but is perceived as if it were. According to the definition given in Encyclopedia Britannica, virtual reality is "the use of computer modeling and simulation that enables a person to interact with an artificial three-dimensional visual or other looked sensory environment. VR applications immerse the user in a computer-generated environment that simulates reality through the use of interactive devices, which send and receive information and goggles, headsets, gloves, or body suits are worn. In a typical VR format, a user wearing a helmet with a stereoscopic screen views animated images of a simulated environment” ("Virtual Reality", 2010).

According to Thalmann (1997), VR refers to a technology capable of transferring a subject to a different environment without the need to move him/ her physically. To this end, the user's sensory organs are manipulated in such a way that his/ her perception is associated with what the virtual environment and not with the actual or physical environment desires. The manipulation process is controlled by a computer model based on the physical descriptions of the virtual environment.

Also according to Thalman, immersion is a key issue in VR systems, because it is fundamental for the paradigm where the user becomes part of the simulated world instead of the simulated world being a characteristic of the real world. The first "immersive VR system" was the flight simulator, where immersion is achieved through a subtle blend of real hardware and virtual image.

For a better understanding of the user’s physical and psychological experience in a virtual environment, there is a need to be familiar with the concepts of immersion, presence, interaction and involvement.

The types of immersion are characterized according to the physical configuration of the interface with the user, fully-immersive (using Head Mounted Display), semi-immersive (large projection screens) or non-immersive (desktop based VR). The level of immersion is measured by the ability of users to interact and communicate with the object in virtual reality in a way similar to how he/ she

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interacts and communicates with objects in the real world. Thus, the less the perception of the real world (see, hear, touch), the greater the classification of immersion in VR will be (Whitman et al, 2004; Gutierrez et al, 2008).

Presence corresponds to the subjective concept that the user perceives there is in a Virtual Environment (VE). The sense of the user’s presence happens when he/ she is aware of "being there" in the environment based on the technology founded on an immersive base (Slater, 1994, Gutiérrez et al, 2008).

Interaction is connected with communication between user and VR system. The capacity of detecting user motions and actions (user inputs) and refreshing VE, in accordance with these inputs, defines interaction. Involvement is related to concentration on VE. Thus, any factor distracting the user can affect his/ her involvement (Rebelo et al, 2011).

In order to visualize products in a VE, various devices are used. A head-mounted display (HMD) is used to visualizing the VE in an immersive manner, since it visually isolates participants from the real world. The motion tracker can be associated with the HMD in order to measure the position/ orientation of the user's head.

To capture users’ movements and actions (user inputs) devices are used such as motion trackers and sensing gloves. These devices have built-in sensors that enable the computer to measure the position of the user’s hand in real-time and to record the flexion of the fingers to enable natural gestures to be recognized. Gloves are necessary especially in tasks involving the manipulation of objects.

3.1 Virtual reality applied to consumer product design

Recent research has demonstrated the advantages and benefits of virtual reality (VR) in many applications, including but not limited to the automotive industry, military research, health systems, entertainment, construction, oil & gas industries etc. However, the use of VR to support consumer products design is still not widespread (Rebelo et al, 2011).

In practice during the product design phase itself, the product can be evaluated with the aid of CAD tools (computer aided design), in three-dimensional models, as well as of physical prototypes (functional or non-functional mock-ups). Physical prototypes, due to their costs and the time taken to construct them, can lead to negative consequences for the competitiveness of the product, which is why virtual prototypes are more commonly used.

It is in this context of substituting or complementing physical with virtual environments and taken this as the starting point that VR technology can support the design of products efficiently and effectively from the early stages of product development (e.g. conceptual design) to the entire product lifecycle activities, in various degrees of immersion, which may be chosen according to the requirements of the design (Ye, J., et al, 2007). Thus, by using VR, the development time and the costs of product design can be reduced as a result of having the possibility of replacing physical mock-ups with virtual prototypes.

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The use of digital prototypes in various design alternatives can be viewed immediately, thus enabling users to provide feedback about them and how they are being used. Furthermore, solutions can be altered interactively and more easily so than if the object were a physical one, which means that more design alternatives in the form of prototypes can be tested, and this is more viable financially.

In addition, virtual environments (VE) enable those taking part in the research to interact safely with all types of products and in any environmental conditions, even when exposed to critical conditions that may put them at risk. VEsl also provide for data collection from the early stages of the design process, with high precision and ecological validity, which is not readily available in the real world (Teixeira et al, 2010).

VR, like any new and emerging technology, - also has limitations- which are related to the display devices, such as limited field of view and/ or low image resolution offered by some HMDs, as well as to interaction devices, such as the limited tactile feedback and haptic (Ye , J., et al, 2007). However, it is understood that the severity of these limitations is related to the quality of the technology acquired, since different devices are commercially available with varying degrees of technological sophistication. Haptic modalities involving the weight sensation, volume and shape adds restrictions that designers can overcome through recent advances in technology.

In the near future, product design based on a VR environment may provide better visualization of the product, thus enabling the designer to coexist in the same virtual space and providing a better appreciation of the geometry and aesthetics of the product. In addition, VR can support the process of participatory and collaborative planning taking place simultaneously, therefore benefiting from the possibility of having several experts and users working simultaneously on the same product and in the same environment, as seen in Mahdjoub et al (2010).

4 CONCLUSION

Setting out from the principle that a definition of usability had been drawn up from the views of several authors, it is essential for a product to meet the usability principles identified and described in this paper and thus to determine whether it does or does not demonstrate usability. To this end, Virtual Reality technology can be used as an important tool support the earliest stages of product development, thus helping the team of designers to develop the first concepts of the product, or even later, during the prototyping stage and more detailed studies. This factor represents an improvement in product quality in ergonomic terms.

Incorporating VR into the process of product design, together with the analysis of usability, leads to the reduced cost of evaluating solutions, thus anticipating issues that, if identified later, could jeopardize the success of the product development, as well as users’ safety and well-being.

Thus, using VR, based on the application of appropriate usability method, becomes compatible with traditional approaches that have been used when

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developing products. As the potential of this technology allows a more natural interaction with virtual models, as noted in section 3.1, there has been an increase in the impetus to develop better support from computing resources for the process of project development. It is believed that the continuing exploration of new technologies and their integration with their application to design will result in the further evolution of product design evaluation systems that are more compatible with the needs of designers and users.

The research that has been developed by the authors intends to conduct an usability evaluation starting from comparative analysis of virtual prototypes of a consumer product, built from the VR, with real physical prototypes. Thus, the intention is to contribute to the area of the usability evaluation and to the application of advanced technologies, more specifically the application of VR in the analysis of the interface between the user and consumer products.

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