Human factors has become concerned with understanding the design process for two main reasons.
First, there is a concern for optimizing the design process, to reduce the effects of chance and errors in design. Secondly, there is the concern to incorporate the requirements of the end user as early as possible when design is relatively fluid. It is argued that this process is product independent (Stanton 1998).
There are three distinct, but not mutually exclusive areas in which human factors should be con- sidered relative to the conceptualization and design of consumer products: safety, operability and maintainability, and attractiveness. In safety, the product should not be designed in such a way that it could fail and cause harm to the user as a result of something unplanned, uncontrolled, or sometimes undesirable (Anton 1989). In operability and maintainability, the product should be easy to operate and maintain, and in attractiveness, the product should be admirable and desirable, but without compromising safety, operability, or ease of maintenance (Woodson, Tillman, and Tillman 1992).
Often, there are many design alternatives to select from when designing a new product. Choosing the optimum one can be difficult when each looks equally good on paper. For example, the use of mockups and prototypes offers the design staff a relatively inexpensive and fast way to test these alternatives. Prototypes and mockups can be used to test safety, usability, and comfort. The term “pro- totypes” and “mockups” can cover a range of functionality, from low-level up to full-function models.
However, mockups are generally smaller and less complete versions of the actual product. As hard- ware can be a mockup, so too can software. Mockups are relatively inexpensive to produce, because only part of the system is simulated. Mockups are particularly well suited to iterative testing, where the design is tested, changed based on the test result, and then tested again. Because of the low cost and low complexity, numerous variations of the design can be mocked up and tested in a short time.
Reducing a system’s weight and size has been a growing trend in the marketplace. System integration and miniaturization has become one of the most distinct trends of modern technological development today, especially in the electronics industry where miniaturized mechanical compo- nents and assemblies, called micro-systems, are typically employed (e.g., the iPod). However, as mechanical components and assemblies become smaller in size and lighter in weight, structural mechanics-related problems, such as vibration, fatigue, reliability, control, moisture exposure, and noise become more problematic. In order to properly address these problems to improve mechanical design capabilities, specific modeling, testing, and analysis techniques, and expertise tailored to such micro-mechanical systems need to be developed. It is necessary, therefore, to develop modeling, testing, and analysis capabilities and control methodologies so that potential problems can be anticipated, minimized, and eliminated at the design stages of micro-systems.
Essentially, there are three major steps in the process of designing a system for use, operation, and disposal. These steps are: (1) preliminary (initial) design, (2) critical (conceptual) design, and (3) final design. However, there are a number of activities (sub-steps) that are associated with these major steps. These activities are enumerated and discussed below.
11.3.1 Define SySteM ObjectiveS
System objectives should be general, not specific, to avoid constraining creativity. Many individuals may see these as defining the mission and vision of the final system; what the consumer product is to do and whom it is to do it for.
11.3.2 Define SySteM RequiReMentS
In defining system (product) requirements, the capabilities, accuracy, safety, and constraints (envi- ronment within which the product will function) need to be taken into consideration in all three steps of the design process. Each evolution of product design through initial, critical, and final design should re-evaluate these system requirements to ensure that they have evolved with each iteration of the product in the design cycle.
11.3.3 Define SySteM functiOnS (functiOn analySiS)
After the system requirements have been determined, system functions need to be defined. These system functions are described at three levels. Level 1 determines the functions of the product that are necessary under normal operating procedures and environments. Level 2 determines the func- tions necessary when the system malfunctions. A recent example of a failure of level 2 would be the non-fail-safe conditions that occurred during the Trans-Ocean owned, and British Petroleum (BP) leased drilling platform accident that happened in the Gulf of Mexico in April 2010. Only one blow-out preventer was attached to the oil well. The blow-out preventer failed, resulting in a massive release of oil into the Gulf of Mexico that endangered both fishing and recreational activities of states along the U.S. Gulf Coast. Level 3 determines the management of the system operations and includes the evaluation of correct operating procedures and the determination of new operating procedures if the initial operating procedures prove to be ineffective and/or inefficient under both normal and system malfunction conditions.
11.3.4 allOcatiOn Of SySteM functiOnS (inteRface)
The allocation of system functions relates to what actions will be controlled by the system (product) and what actions will be controlled by the operator (product consumer). This is an important step in determining the level of unburdening (the action of off-loading operations responsibility from the operator to the system) that anticipates the activities normally assigned to the user and relegates
these operations to the system. As advances in expert systems improve, this type of unburdening improves and is related to user focus group input into the design of consumer products. These focus groups (discussed subsequently) also determine the level of mechanization and automation that is built into consumer products. For example, iPods are designed to re-shuffle music selections based on the listening history of the user.
11.3.5 SelectiOn Of DiSPlayS anD cOntROlS
The selection of displays and controls providing information to the product user (consumer) and the controls that they use to interface with the product are important and may rely on age, gender, and cultural information provided by product evaluation during the three design phases. The perception, understanding, compatibility, and integration of displays and controls are integral to all phases of the design cycle. Perception of displayed information as well as controls (activation symbology) will determine the usability of consumer products and the level of satisfaction users have with consumer products.
The correct interpretation of the information presented to the user (including user manuals) will also determine the appropriateness of user actions (decisions), the acceptability of those decisions by the system, and the acceptability (usability) of the product as a whole. It is also important to consider the selection of controls and displays that will support perception, integration, and decision making that may take place quickly, especially in emergency and/or system malfunction conditions.
11.3.6 DeSign Of the uSeR Place/uSeR enviROnMent
The design of the user place/user environment is focused on the placement of controls and dis- plays where they can be seen, heard, and used by the appropriate operator. Such displays may be designed for either the parallel or serial presentation of information. Parallel presentation of information implies the presentation of multiple sources of information on multiple displays. An example of such information presentation would be using multiple displays with either laptop or desktop computer systems, where the user can display primary document sources while displaying information associated with particular files and/or applications (e.g., displaying document files and email accounts on different displays at the same time).
The formatting of such displays is, now, predominately under user control. That is, the user deter- mines the configuration of information that is shown on the display(s). As electronic technology improves, the ability of consumers to configure user display and control interfaces improves. This is exemplified by both the iPhone and the iPad.
Assuring control-display compatibility is also important in the design and usability of consumer products. Configurations, either under or outside consumer control, are based on user experience, user expectations (population stereotype based on cultural and experiential expectations), user and designer knowledge, and user skill.
Other important user environmental issues in design that are related to usability (the following section) are communication (user instruction and user feedback), satisfaction during product use, motivation for product use and providing user feedback to designers, and cohesiveness of user-prod- uct interactions. These aspects are important considerations that directly relate to product “usability”
evaluations by the user and can translate into feedback for product modification and improvement.
Product characteristics that are directly related to user assessments of “usability” and that are directly related to product design efforts are: the location of controls and displays as they relate to product use; the location and access to operable parts such as battery access and replacement, ease of product operation, and ease of product repair by the user. Within the last decade, reparability has given way to disposability where it has been cheaper and/or more convenient to replace a con- sumer product than have the product repaired. However, in light of the more recent concentration on recycling and green design, reparability is now coming back into fashion.
11.3.7 eMPiRical evaluatiOn Of alteRnative DeSignS
The empirical evaluation of alternative designs has moved into the framework of contextual evaluation. Scenarios are developed in laboratory-supported environments of potential use in which products are tested and assessed by potential user groups. Feedback from such evaluations are fed back into the product design process to represent user evaluation, in attempts to provide products that meet the needs of target user groups. Experimental designs and tests (laboratory and/or field) are developed to provide more appropriate feedback to designers before the product is actually manufactured for consumer consumption. These efforts are done to limit re-design efforts and, hopefully, provide products that consumers are more willing to accept and purchase. It should be noted that the results of such evaluations are only as good as the “representation” of the test groups to the potential consumer groups in the target market.
11.3.8 DevelOPMent anD SelectiOn Of tRaining PROceDuReS
The development of training procedures (user manuals) is focused on three areas. These are instructions to users regarding weaknesses (limitations) of the products and to instruct users not to use products under these conditions (warning of misuse). Instructions are provided (if actually read and reviewed) to aid in the ease and efficiency of operation of the product. There is a litany of literature regarding the efficacy of providing user manuals for use, as it is human nature to rely on user innate ability to understand product use. As is now common, computers are purchased and delivered to consumers without user manuals; they are available on-line if installation and opera- tion problems are encountered. Furthermore, in the age of globalization, user help desks are often located outside the user’s location of use. In such cases, users find attempting to obtain assistance using such off-site help services frustrating and often resort to trial-and-error or finding assistance by other means. It would be advised that user manuals be provided that focus on communication in terms of non-familiar system users, concentrating on error limitation, reduced product start-up time, reduced down time, and reduced system maintenance. Although green efforts are designed to reduce the use of “paper” manuals, software-based manuals with keyword searches would be an efficient and convenient way of providing information to end users that would not illicit stress during product installation, start-up, and/or use.
11.3.9 iMPleMentatiOn Of DeSign
The implementation of product designs should follow prototype and field-testing evaluations of each design resulting from each stage of product design. These implementation efforts include product redesign, based on focus group feedback, evaluation of user comments and user product ratings, and evaluation against alternatives.