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Representing User Activity and Product Function for Universal Design
Proceedings of IDETC/CIE 2009 ASME 2009 International Design Engineering Technical Conference & Computers and Information in Engineering Conference August 30-September 2, San Diego, California, USA DETC2009-87507 REPRESENTING USER ACTIVITY AND PRODUCT FUNCTION FOR UNIVERSAL DESIGN 1 Vincent Kostovich, Daniel A. McAdams , and Seung Ki Moon Department of Mechanical Engineering Texas A&M University College Station, TX 77843, USA ! ABSTRACT This paper presents a product analysis framework to improve universal design research and practice. Seventeen percent of the US population has some form of a disability. Nevertheless, many companies are unfamiliar with approaches to achieving universal design. A key element of the framework is the combination of activity diagrams and functional models. The framework is applied in the analysis of 20 pairs of products that satisfy a common high level need but differ with one product intended for fully able users and the other intended for persons with some disability or reduced functioning. Discoveries based on the analysis include the observation that differences in typical and universal products can be categorized functionally, morphologically, or parametrically different than typical products. Additionally, simple products appear to be made more accessible through parametric changes whereas more complex products require functional additions and changes. 1 of kitchen tools with comfortable grips easily accessible to arthritic customers [3]. In subsequent years, the market segment shifted to younger users interested in cooking with ergonomically friendly peelers, bottle openers and other cooking utensils. As a result, the O.X.O Good Grips products are an oft-cited example of a universal product success. An example of a vegetable peeler from the Good Grips line is shown in Figure 1. 1. INTRODUCTION Seventeen percent of the US population has some form of a disability. Additionally, a high percentage of people with disabilities have a negative impact on their education and working environment as a result of their disability. Roughly two in five people with disabilities do not even finish high school. Even if they obtain a post secondary degree, disabled people often face some form of discrimination at work [1]. As persons age, the probability of them developing a disability increases. As life expectancy rises, a greater percentage of the population will have some form of disability [2]. Universal designs are needed across the entire product spectrum. Two examples of successful companies that have implemented universal design concepts are O.X.O and Toyota. Initially, O.X.O designed their Good Grip product-line as a line Figure 1.O.X.O Good Grip Serrated Vegetable Peeler. The Universal Design showcase in Japan highlights universal design concepts [4]. Figure 2 shows an example from an exercise in which universal design was implemented from the ground up while developing minivans and sedans. For instance, the chairs, knob placement, and trunk configurations are all designed to be universal as stock items rather than after market add-ons. For example, the Toyota Crown Comfort has a mechanical handle that will pull out and swivel a rear seat towards the entering passenger as shown in Figure 2. It is worth noting that aside from this pull out handle, the configuration of the seat is very similar to any other sedan. Though there is additional design effort needed to design this universal seat, that material and manufacturing costs would !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !055&677!899!:#&&67$#;56;:6!*#!*)'7!8<*)#&!8*!5=:858=7>*8=<?65<@!.A.B CD,BACEF?! 4 ! 4! ! "#$%&'()*!+!,--.!/%!0123! likely only be marginally higher than a typical seat. An advantage of including these features early in the design process and integrating them in a universal product is the avoidance of the high costs of retrofitting the vehicle later for disabled users. Though seemingly simple to execute, these examples of successful universal design serve as exceptions, not the rule. universal design, their most common answer was thinking that universal design is too hard to implement. Clearly, a key barrier to universal design is lack of knowledge about its practice and what tools can be used to develop a universal product. While these barriers do exist, there are companies and products that have achieved success while implementing strategies to achieve universal products. In addition, there are principles and rules developed by researchers and companies explaining what a universal product does. However, there remain significant knowledge gaps that would allow universal design to be implemented broadly in product design. In this paper, we present a framework for performing research that enables an understanding of product differences in the context of universal design. Additionally, the framework allows for the recognition of these differences early in the design process. The focus is on the early recognition of differences and commonalities in typical and universal products to recognize opportunities for product families that contain both typical and universal products. The remainder of this paper is organized as follows. Section 2 reviews related literature and background. Section 3 describes the research approach and method for supporting universal design. Section 4 discusses a case study comparison of twenty product pairs of typical and universal products. In Section 5, conclusions and future work are presented. Figure 2.Toyota Crown Comfort Swivel Chair Sequence [5]. As the population of persons with a disability grows, so does the ethical and economic pressure to provide that population with products that provide services and value. Nevertheless, many companies are unfamiliar with approaches to applying universal design. One of the authors of this article had a recent conversation with a research engineer from a large consumer electronics manufacturing firm in which he asked: “What is your biggest design challenge?” The response was simple: “Universal design, how do you do it?” Before continuing, it is worth briefly touching on terminology. Within the community that serves persons with disabilities, multiple terms are used, including universal design, accessible design, inclusive design, design for all, transgenerational design, rehabilitation design, and barrier free design, to indicate goods and services for persons with disabilities. Below, we do present some clarification on the relationship between these different types of design for persons with a disability. Nevertheless, there is ongoing discussion about the precise meanings, overlap, and best use of the terms. Though these discussions have philosophical and practical importance, they are not crucial to the discussion here. With awareness that at times one of the other terms would be more accurate, we will use the term universal design here to indicate design for persons with disabilities. In a United Kingdom study of 87 design, manufacturing, and retail sector companies, existing barriers to universal design were explored [6]. Initially, these barriers were evaluated based on the companies’ general awareness of universal design. When asked why the designer, or company, didn’t perform universal design, ‘not aware’ was the most frequent response. Furthermore, for those ‘not aware’ the most popular answer was lack of knowledge and tools creating a barrier to implementing universal design. For those participants who were ‘extremely aware’ of the concept of ! 2. LITERATURE REVIEW AND BACKGROUND Universal design has many closely related types of design. For example, transgenerational design focuses on design for older people and rehabilitation design focuses on design for those with a new or temporary disability. Transgenerational and rehabilitation design are closely related as they focus on a specific segment of the population that requires the easiest means of using a product. This ease of use idea is similar to principles of universal design [7-9]. There are also existing typical and universal design methods that have been documented and explained [10, 11]. 2.1 Motivation for Universal Design A universal design is a design that can be used equally as well by people of any ability: it does not discriminate against users based on their ability. Accessible design is another term used for describing design for persons with a disability. Accessible design is frequently used to describe specific modifications of typical designs for someone with a disability such as the addition of a ramp entry to a building. Adaptable design can also be universal in the sense that it changes an existing product by merely modifying a part or component to make it easier to use [12]. As a result, the stigma of using an accessible or adaptable product may still be prevalent despite its ease of use. Figure 3 below shows how accessible, universal, and adaptable designs vary across the design space [12]. ,! ! "#$%&'()*!+!,--.!/%!0123! universal design as expressed by the terminology used in the introduction of this paper [18]. 2.2 Universal Design Methods More comprehensive summaries of universal design can be found in The Universal Design Handbook [19], Fisk and Rogers [20], and Salvendy [21]. The research approach proposed here builds on recent developments from the universal design, engineering design, and health communities. The review of related work is focused as such. The landscape of universal design literature is vast and contains significant coverage of historical and social context. As an example, of the sixty-two chapters in The Universal Design Handbook, fifty-two chapters have significant coverage focused on the history of universal design, the rationale behind it, legal issues, documentation of workshops, or similar. Notably, about twenty-four chapters provide descriptive guidelines and quantitative requirements for universal architectural design. Only about seven chapters contain guidelines, case studies, or other content that provides some insight into universal product design. The volume and emphasis of universal design research publication mirrors the coverage in The Universal Design Handbook. Though universal design of architecture is not a solved problem, there is a large and high quality set of resources available for architectural design [22-27]. The materials available include qualitative guidelines as well as quantitative parametric guidelines such as room layouts, counter heights, dimensional requirements for appropriate sight lines in large classrooms, and etc. The available guidance for universal architectural design far surpasses what is available for universal product design. A team of researchers organized through The Center for Universal Design at North Carolina State University has compiled seven principles of universal design [9]. The seven principles are: 1. equitable use, 2. flexibility in use, 3. simple and intuitive use, 4. perceptible information, 5. tolerance for error, 6. low physical effort, and 7. size and space for approach and use. For each principle, several guidelines have been created. For example, principle 6 has a guideline of “minimize repetitive actions.” These principles have been well received by designers in a range of disciplines. Though the seven principles of universal design provide high-level guidance, they provide more of an evaluation aid than a design or synthesis aid for product design. Continuing with principle 6 as the example, products need to be designed for low physical effort. Minimizing repetitive actions helps with reducing effort, but how does one design a product to minimize repetitive actions and require low physical effort? Also, as stated by the compilers of the seven principles: “…the practice of design involves more than consideration for usability. Designers must also incorporate other considerations such as economic, engineering, cultural, gender, and environmental concerns in their design processes [9].” Another set of design principles and guidelines for product design focuses more on functions of a product and how to Figure 3.Design Venn Diagram-Overlap shows designs that are in more than one category [12]. As shown in Figure 3, there is an opportunity to create a universal design from more commonplace adaptable or general designs. However, as a designer, there is a tendency to focus on adaptable or merely general designs because of cost, market or time constraints. These constraints are associated with product assessment techniques and are believed to be the most common problem with universal design because of extra design steps [13]. In addition, it is often the lack of education and tooling that prevents a company from reaching the overlapping areas of universal design. Companies desire a quick, visual, and an easy to understand tool with associated product examples and case studies in order to feel more comfortable implementing universal design techniques. Designers want to know how to use the plethora of information about universal design in a more systematic way [14]. Designers are frequently unaware of differing customer preferences of those with different physical and mental disabilities. The designer is uncertain how to incorporate universal design into the design process [15]. Moreover, designers tend to work reactively rather than proactively. For instance, a designer may react to a definite set of customer needs and focus on satisfying them. In the case of universal design, a designer should proactively focus on the product’s capabilities and ability to work with a variety of consumers [16]. Reactive design focuses more on redesigning a specific part of an existing device to satisfy a customer. However, if the user is redefined at the front end of the design process, the designer will produce a more universal product. One aspect that delays the development of methods for universal design is discussion of the interpretation of the meaning as well as the general challenge of designing for those with a disability. For example, designs that either focus too much on specific market segments such as transgenerational design are sometimes criticized for their shortcoming rather than being celebrated for what they can do. Transgenerational design theory describes how older adults are the focus for design often misinterpreted as universal [7]. People may also get this type of design confused with rehabilitation design dealing with impairments. Even cultural interpretations of how to tackle universal design make it a less ubiquitous method. For instance, Europe has a method called the User Pyramid Approach [17] whereas the US, Japan and Australia focus on ! 4! ! "#$%&'()*!+!,--.!/%!0123! fulfill these guidelines in order to cover as many disabilities a possible. The five function areas are: output/displays, input/controls, manipulations, documentation, and safety. For each function area, five disabilities are addressed by stating problems and example solutions [28]. To take this approach one step further, another means for evaluating the universality of a product is by associating exclusion scores for various human attributes. If the score is low, a user with a disability similar to one of the five function areas addressed in the previous approach will have difficulty using the device. This product assessment method includes: product description, context of use, sequence of use, capability, score and justification [29]. Keates proposed a seven-step approach for universal design by modifying the traditional three-step [11]. As shown in Figure 4, the first two levels of the seven-step approach parallel the first two into a traditional design method to make it universal. Level 3 describes user’s perception of the product or how the physical layout of the product affects the user interaction. Often anthropometric, ergonomic and empirical data from trials are needed to complete design at this level. Level 4 focuses on the user’s mental or cognitive interaction. Cognitive walkthroughs are used to correlate user system behavior to user expectations. Thirdly, level 5 focuses on user input or interaction with the product and relies on similar techniques as those used at level 3 to address design at this level [30]. Vanderheiden has developed a set of guidelines for the design of consumer products [28]. Some of these guidelines are useful only for evaluation. Others include suggestions that augment product synthesis. For example, guideline I-2 is maximize the number of people who can find the individual controls or keys if they can’t see them. To help synthesize a solution that achieves such a goal, this guideline includes suggestions for shapes of computer keyboard keys (or similar) that will allow someone with a sight limitation to locate the correct key. The guidelines and suggestions tend to be focused on products surrounding electronic communication or information technology but should be extendable to product design in general. Housed in the Center for Inclusive Design and Environmental Access at the University of Buffalo is an active group of researchers with focus on universal design [31-34]. Though this group is focused on architectural design and comes from an architectural background, they have performed research on appliances and other applications that extend to product design. A team of researchers at the University of Cambridge has produced implementable results for universal design [35-40]. The focus of this research group has been in modeling user groups, creating product assessment methods, and extending the needs of universal design to modern product design processes. The results of the Cambridge team are the most directly applicable to product design. Their effort has been primarily focused on the user and the design challenges of accommodating that user. ! Figure 4. The 7-level design approach [11] Universal design is an active research area. Nevertheless, fundamental work applicable to product design is still a sparsely populated space. Universal design is more of an objective than a systematic design approach. There is little in the way of a prescriptive approach to universal design with more detail than simply broad design objectives [41]. Additionally, though creating modular products that minimize modification to become universal is a recognized approach to universal design, specific knowledge and methods to do it do not exist [40]. 3. PRODUCT ANALYSIS FRAMEWORK AND RESEARCH APROACH Our interest is early in the design effort where product function is being established and solution concepts are being generated to provide that function. Our goal is to understand the differences and similarities in typical and universal products and being able to do so early in the design effort. Though beyond the scope of the work presented here, this interest is related to a future goal of creating product families that include 5! ! "#$%&'()*!+!,--.!/%!0123! typical and universal products built on some common product platform. Thus, understanding the relationship between user activity, disability, and common and differing product characteristics is important. Here we develop an analysis framework that allows the comparison of two products that fulfill the same overall need. The comparison is focused on the result of decisions that are made early in the design process, i.e. what functions must the product have and what is the form and characteristic of the solution that will best provide that functionality. The framework and analysis method are illustrated with an example. difference indicates the case in which the universal and typical product have the same functionality, solve the required functionality through essentially the same solution principle and form, but have a different parametric embodiment. For example, the handgrip of an object could be bigger or more ergonomically designed as exemplified by the O.X.O Good Grip vegetable peeler shown in Figure 1. Based on the notions of product pairs, functional differences, morphological differences, and parametric differences, we want to compare product pairs in the context of user activity and product function. To do this, we combine activity diagrams and functional models into a single representation that we will term an actionfunction diagram. Before introducing the actionfunction diagram, activity diagrams and functional models are briefly reviewed. An activity diagram is a sequence of user interactions from purchase to recycling or disposal [10]. This sequence may include parallel or series actions. A series of actions implies that one action must occur before another. Whereas, a parallel action implies that two actions occur simultaneously. Activity diagrams model the entire range of user product interaction to better design the product for each user activity. An example activity diagram for a typical box cutter is shown in Figure 68.The activity diagram shows the user interaction process from purchasing and unpacking the cutters to cutting cardboard with them. 3.1 Product Analysis Framework We will use the term product pair to refer to two products that satisfy the same high level need or provide the same overall black box functionality but differ in ease of use for someone with a disability [42]. Figure 5 illustrates a product pair of utility cutters. The Fiskars Rotary Cutter and the typical box cutter provide similar paper and cardboard cutting but the Fiskars Rotary cutter has features that make it preferable for users with reduced hand functioning. Figure 5. A product pair of a Fiskars Rotary Cutter (above) and standard box cutter (below) As product pairs are analyzed, we want to compare them in terms of attributes crucial to making the product accessible and relevant to decisions that are made early in the design. Thus, we will compare product pairs based on differences in functionality, morphology, and parametric realization. A Functional Difference reflects the situation in which the typical and universal product have differing functionality particularly as it pertains to the making the universal product more accessible. As an example, some signage adds the function of “export tactile signal” embodied as Braille lettering to become accessible to an unsighted user. A Morphological Difference refers to a product pair that has the same detailed functionality but the typical and universal product solve said functionality via a different solution principal or form. For example, an “allow a degree of freedom” function could be solved by either a mechanical linkage or springs. Both the linkage and the spring provide a similar motion but their component makeup is different. A parametric ! Figure 6. An example of an activity diagram for box or paper cutter A functional model is a graphical depiction of detailed product functionality. Functional models include functions, generally represented as verbs, which describe the desired transformations of flows, which are generally described using nouns. The process for creating a functional model depends on the modeling methodology chosen but in general involves the following basic steps: 1. 6! Create a black-box model that includes the overall functionality of the product along with external flows, ! "#$%&'()*!+!,--.!/%!0123! 2. For each input flow in the black-box model identify the sequence of functional transformations that are required to produce one or more of the output flows, 3. Aggregate these function sequences into a complete functional model for the product, 4. Assess the model’s coverage of customer needs and system requirements, add functions/flows or decompose as required. A range of reasons for creating a functional model during product design are detailed by Otto and Wood [10]. In general, the primary reason is to create a solution-neutral method of representing what a product needs to do without assuming how it is going to do it. This mapping of what to how represents the remainder of the conceptual design process. Figure 8. Generic template for an actionfunction diagram Specifically with the goal of understanding the design differences between universal and typical products, actionfunction diagrams include an indication of the differences between the typical and universal products being compared as well as the user activities and product functions. Different product functionality is indicated by a bold-lined function box. Common product function but different morphology is indicated with a double lined function. Common product function and morphology with different parametric implementation is indicated with a shaded function box. Where the typical and accessible or universal products are the same is indicated with a standard function box. Frequently, functional models use function and flow terminology from the Functional Basis in order to maintain consistency from one product to another [42]. A functional model for a standard box cutter intended for a typical user is shown in Figure 7. 3.2 Research Approach Figure 9 illustrates the steps used to explore differences between typical and universal products. For each product pair, a common activity diagram is constructed, then a functional model is made for the both the typical and universal products, then the functional models and specific products are compared. The activities are performed using tabular comparisons of the actionfunction diagrams to highlight the differences and similarities between the product pair. A template table is shown in Table 3. Figure 7. A Functional model for standard box cutter An actionfunction diagram is the combination of an activity diagram and a functional model together into a single representation. Figure 8 shows a template for the actionfunction diagram. In an actionfunction diagram user activities are represented by dashed rectangles with related functions clustered within each activity. ! Figure 9.Outline for Visual Analysis 7! ! "#$%&'()*!+!,--.!/%!0123! Table 3. Product Template Typical Product Pair Actionfunction Diagram blade. The simple pushing in is easier then the push in then push forward motion. Additionally, the actual force to push the switches on the rotary cutter was less then the force needed to either push in or forward on the utility knife. Both the typical utility knife and the rotary cutter provide the function of transferring human energy into the device to move the blade. The difference is categorized as morphological as there is not clear parametric representation that encompasses both concepts. The differences between the product pair are shown in the actionfunction comparison in Table 4. Universal Product The products are carefully analyzed in terms of differences as it pertains to improved usage for a user with a disability or reduced functioning. Specific focus is placed on how the products do or don’t implement the principles of universal design. If impact of a design difference on usage is not clear, both products are acquired and used to perform a physical testing comparison. We illustrate the design and analysis framework and approach through an example of a paper and cardboard cutter product pair, in this case the Fiskars rotary cutter and standard box cutter as shown in Figure 7. Both products provide the same overall usage of cutting but are different in their embodiment. To start, the rotary cutter has a more ergonomic handle. In this example, the handle which provides the secure hand function is based on the same basic principle, but was shaped differently, specifically more ergonomically, for the universal cutter. Thus, this difference is shown as a parametric change in the actionfunction comparison shown in Table 4. The rotary cutter has a circular blade with a guard whereas the standard box cutter has a retractable angled blade. The difference in blade shape and motion impacted the effort needed to cut. The rotation of the circular blade naturally added a little sawing motion to the material-blade interface reducing the total pushing force needed to cut paper and cardboard as the user pulled the cutter across paper or cardboard. Also, the rotary cutter can cut with a pushing away motion by the user whereas the traditional utility knife only works well with a pulling toward the user motion. This is a morphological difference as rotating is a different principle for cutting than just pulling the blade through the material to be cut. The actionfunction diagram shown in Figure 4 represents this morphological difference in the solution of the convert human to mechanical energy function. The blade extension and retraction design of the cutters is significantly different. There are two switches to lock and unlock the blade for the rotary cutter whereas only one switch is for both extending and retracting the blade for the standard box cutter. In the case of the rotary cutter, the blade extensions and retraction switches are both activated with a simple pushing in, or pushing down, motions on a single axis of travel. The blade on the rotary cutter is spring loaded to snap back into place when the retraction switch is pushed. For the traditional utility knife, the user pushes the switch into the knife to release a lock, then forward along the length of the knife to extract the ! Table 4. Actionfunction product pair comparison for the standard utility cutter and the Fiskars rotary style cutter. Shown here in a single column for readability. An actionfunction diagram of a typical utility cutter. An actionfunction diagram of the Fiskars rotary cutter. 4. CASE STUDY AND RESULTS Twenty product pairs ranging from automobile interiors to scissors are compared in this study. Products marketed or generally accepted as universal or accessible are chosen along with similar typical products to form the product pair. Most of the products are handheld kitchen utensils. However, products such as a typical recliner and universal chair lift and automobiles are included. The vehicle product pairs have modification to improve user egress and ingress accessibility. Appendix A shows a table of the twenty products studied. As with the paper and cardboard cutter product pair analyzed 8! ! "#$%&'()*!+!,--.!/%!0123! above, a comparison using the actionfunction diagram and experimentation is performed on each product pair. Results are summarized and discussed here. In the study of products, the user activities associated with some parametric, morphological, or functional difference in the product pair are adjust, apply force, drive, exit, grab, position, press, remove, speak, squeeze, touch, translate, transport, and use human force. These differences occurred primarily where direct contact with the product took place and are primarily relevant to reduced hand strength and motor functioning. The user activities for which there is no associated difference in the product pairs studied are approach, attach, connect, demolish, dispose, drive, exit, insert, install, look, program, purchase, read instructions, recycle, release, replace, retract, return, sell, stand, start, store, stop, twist (turn), unpackage, wait, and walk. These activities generally occur early or late in the product life cycle. These results appear to be based on what has been done in universal design practice as opposed to a fundamental result of what needs to be done in a broad and general context. Such a result is consistent with the sample size of the study and the challenge and complexities of universal design. Also, during the study the author team noticed that though some activities did not relate to design differences, they should have been. For example, the product pair solutions for the activities of read instructions and unpackage were effectively equivalent for product pairs. Nevertheless, the instructions were not always particularly accessible to someone with reduced vision functioning. Similarly, the heavy plastic blister packs that many of the products came packaged in are difficult to open for a user with reduced hand strength and motor function. Table 5 shows the specific type of design change correlated with each specific activity. Complex activities of drive and speak result in a more comprehensive change (function). Simple activities such as grab, position, press, result in less comprehensive change. Based on the product pairs studied, no specific conclusions on trends of what activities are related to what specific types of changes can be drawn. Table 6 indicates which functions did not feature a parametric or morphological difference nor were they a functional difference in a product pair. Many of the functions were import or convert functions. In general, these functions are internal to the functional model. Though, this is not always so as exemplified by the position hand and guide hand functions. Table 7 summarizes the parametric, morphological, and functional differences between universal and typical products analyzed. The percentage difference reflects the changes in the product at a functional level. For example, a parametric change in 1 function out of a total of 10 functions in a product would result in a 10% parametric change. The measure uses the typical product functionality as a base for comparison thus enabling for greater than 100% change. For example, the typical recliner only had four functions. The universal recliner added 9 additional functions thus resulting in a 225% functional difference. ! 75% of the products had a parametric difference, 50% of the products had a morphological difference, and 65% of the products featured a functional difference. For all 20 products, the average parametric difference is 8%, the average morphological difference is 6%, and the average functional difference is almost 50%. Table 5. Activity and Design Changes Activity Parametric Adjust Morphological Function X Apply force X Drive X Exit X Grab X Position X Press X Remove X Speak X Squeeze X Touch Translate X X Transport X Use Human Force X Table 6. Functions not related to any product pair design difference. 0:*;<*=! >=:)<?':<@! =?=&(%A! B>$#&*! ><(?=*':! =?=&(%A! "#?C=&*! =@=:*&':<@! =?=&(%! *#! 0:#;D*':! =?=&(%A! B>$#&*! D#@'E! "#;$@=! D#@'EA! B>$#&*! C'D;<@! D'(?<@A! 3F$#&*! )<?EA! G#D'*'#?! )<?EA! 3F$#&*! C'D;<@! D'(?<@A! G#D'*'#?! );><?A! H;'E=! )<?EA! G#D'*'#?! D#@'EA! B>$#&*! <:#;D*':! =?=&(%A! I=>#C=! D#@'EA! B>$#&*! )<?EA! 1=:;&=! )<?EA! B>$#&*! );><?A! 1=$<&<*=! D#@'EA! B>$#&*! );><?! =?=&(%A! 1*#&=! D#@'EA! B>$#&*! );><?! =?=&(%A! J&<?DK=&!<:#;D*':!=?=&(%A!J&<?DK=&!);><?!=?=&(%A!J&<?D@<*=! )<?EA!J&<?D>'*!D'(?<@! 9! ! "#$%&'()*!+!,--.!/%!0123! Table 7. A summary of difference between the typical and universal products analyzed. Product Total Functions Can Opener 12 Pruning Shear 10 Signage 2 Cutter 9 Sink 8 PT Cruiser 8 Ford Focus 21 Scissors 12 Food Container 10 Telephone 7 Toilet Seat 7 Recliner 4 TV Remote 9 Ear Phones 11 Arm Chair 7 Cheese Grater 12 Bottle Opener 11 Potato Masher 13 Vegetable Peeler 12 Jar Opener 11 Parametric 8% 10% 0% 11% 25% 0% 14% 8% 10% 14% 0% 0% 22% 9% 0% 8% 9% 8% 8% 9% Morphological 16% 20% 0% 22% 0% 12% 5% 0% 0% 0% 14% 11% 0% 0% 14% 0% 0% 0% 0% 9% a product needs specific function, morphological, or parametric embodiment. Within the products studied, the majority of differences between universal and typical products are related to user hand manipulation of the product. Functions that are internal to the product (those that do not have an exciting or entering flow that crosses the product boundary) generally remain the same for the product pairs studied. Additionally, boundary functions not related to human flows generally remained unchanged. Universal design remains a challenge. Toward the goal of creating a fundamental framework for universal product family design, many questions remain. A deeper understanding of classes of products, classes of functions, classes of user limitation, and the interaction between them needs to be discovered so that designers can reason about integrating product functions and features into a universal product family. Using the framework developed here, further study can reveal what functions are common across a range of typical and universal products. With this knowledge, designers can extend current product family design methods to create universal product families that share these common elements as the product platform and extend to a product family with the unique elements. Functional 58% 0% 200% 0% 125% 100% 33% 16% 0% 14% 86% 225% 0% 18% 100% 0% 0% 0% 16% 0% The fact that the average functional differences is about six times greater than parametric or morphological differences indicates that universal design needs to be considered early in the design process. Product function drives many early design decisions including product architecture. Parametric redesigns are often cost effective. Changing product function is a more complex and expensive task. Of the products studied, simple products feature less functional change than complex products. For example, the cheese grater, bottle opener, potato masher, food container, and jar opener use parametric changes to be more accessible. By contrast, the sink, can opener, and recliner contain significant functional changes. The universal products adding functionality are often adding functionality that the user provides for the typical product. For example, the can opener adds a motor to prove the cutting motion and torque that the user provides with a typical can opener. Similarly, the recliner adds functionality that essentially stands the user up. REFERENCES [1] Virtual Ability,Inc. ,2009, “Disability Resources”. Retrieved January 15, 2009, from Virtual Ability,Inc: )**$LMMC'&*;<@</'@'*%N#&(ME'D</'@'*%O&=D#;&:=DN<D$F [2] U.S. National Center for Health Statistics, 2005, “National Vital Statistics Reports (NVSR) Deaths: Final Data” , 56(10) [3] Cagan, J., & Vogel, C. M. ,2002, Creating Breakthrough Products-Innovation From Product Planning To Program Approval. Upper Saddle River, Pearson Education,Inc,New Jersey. [4] Amlux Toyota Co.,LTD,2006, “Toyota Universal Design Showcase”, Retrieved January 15, 2009, from Toyota Universal Design Showcase: 5. CONCLUSIONS AND FUTURE WORK In this paper we explored the relationship between user activity, product function, and product form as it pertains to differences in typical and universal products. Specifically, we explored a research framework that uses the formal design methods of activity diagrams and functional models. We combined these methods into a single graphical representation called an actionfunction diagram that allows the user to see functional, morphological, and parametric differences between a typical and universal product that provide the same overall use. Using this approach, 20 products were studied to understand the trends in function, morphological, and parametric differences in typical and universal products that provide the same overall usage. The actionfunction diagram provided a clear, repeatable framework for analyzing products for differences as it pertains to typical and universal products. Though used in this study as a research framework, the actionfunction diagram framework is applicable to design activities. The actionfunction diagram clusters product functions as they relate to user activity, thus the designer can identify activities, and user limitations, for which ! )**$LMMPPPN>=(<P=/N(&NQ$MREDM3?(@'D)M [5] Toyota,2009, “Crown Comfort”, Retrieved January 15, 2009, from Toyota: http://toyota.jp/welcab/crowncomfort/kaiten/ [6] Goodman, J., Dong, H., Langdon, P., & Clarkson, P. ,2006, Designing Accessible Technology. Springer-Verlag London Limited,Germany. 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