Scholarly article on topic 'Usability Evaluation of CADCAM: State of the Art'

Usability Evaluation of CADCAM: State of the Art Academic research paper on "Computer and information sciences"

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Abstract of research paper on Computer and information sciences, author of scientific article — Yujiang Li, Mikael Hedlind, Torsten Kjellberg

Abstract Today, for development of product and production, computer-aided design and manufacturing (CADCAM) maintain a significant role in interaction activities between human and computers. The major objective of computer-aided technology is to simplify engineer's work in collecting, using, and sharing information so that human can maximize the usage of their unique abilities, e.g. creativity and innovation. User experiences (UX) will substantially determine outcomes of such intellectual engineering activities during human computer interaction (HCI) with the CADCAM systems. Usability is a key feature of software ergonomic, and has been standardized as an important property of software quality. Concerns for usability of all kinds of ordinary software interface have been expressed by a lot of studies. Evaluation is always a central activity when practicing usability in an iterative product development process. It can be expected that employment of usability evaluation for CADCAM will be highly valued towards a better level of Human Computer Interaction (HCI). Nevertheless, researches involving usability in this particular domain are very rare. This paper reviews a limited number of publications with such concerns and investigates the current context of use of CADCAM software. Then existing evaluation techniques are introduced and discussed for their feasibility in manufacturing industry based on previous studies.

Academic research paper on topic "Usability Evaluation of CADCAM: State of the Art"

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Procedía CIRP 36 (2015) 205 - 210

CIRP 25th Design Conference Innovative Product Creation

Usability evaluation of CADCAM: state of the art

Yujiang Lia*, Mikael Hedlindb, Torsten Kjellberga

aKTH Royal Institute of Technology, Brinellvagen 8, Stockholm 10044, Sweden bScania CVAB, Verkstadsvagen, Sodertalje 15138, Sweden

* Corresponding author. Tel.: +46-8790-8384. E-mail address:


Today, for development of product and production, computer-aided design and manufacturing (CADCAM) maintain a significant role in interaction activities between human and computers. The major objective of computer-aided technology is to simplify engineer's work in collecting, using, and sharing information so that human can maximize the usage of their unique abilities, e.g. creativity and innovation. User experiences (UX) will substantially determine outcomes of such intellectual engineering activities during human computer interaction (HCI) with the CADCAM systems. Usability is a key feature of software ergonomic, and has been standardized as an important property of software quality. Concerns for usability of all kinds of ordinary software interface have been expressed by a lot of studies. Evaluation is always a central activity when practicing usability in an iterative product development process. It can be expected that employment of usability evaluation for CADCAM will be highly valued towards a better level of Human Computer Interaction (HCI). Nevertheless, researches involving usability in this particular domain are very rare. This paper reviews a limited number of publications with such concerns and investigates the current context of use of CADCAM software. Then existing evaluation techniques are introduced and discussed for their feasibility in manufacturing industry based on previous studies.

©2015TheAuthors.PublishedbyElsevierB.V. This is an open access article under the CC BY-NC-ND license (

Peer-review under responsibility of the scientific committee of the CIRP 25th Design Conference Innovative Product Creation

Keywords: CADCAM; HCI; Usability; Usability evaluation; UI

1. Introduction

Technology makes sense only when it serves human best. Traditional technology has been augmenting human's physical abilities for thousands of years, while information technology will augment human's intellectual abilities, stated by the innovator of the project to build the first computer, Vannevar Bush [1]. No matter how technology evolves, the end users of digital systems will be human, and the ultimate demand of the systems will be satisfying human's requirements. Based on cyber-physical systems and Internet of Things, new concepts such as Industry 4.0 [2], cloud manufacturing [3] and Industrial Internet [4] put high requirements on digitalization of manufacturing industry.

Today, CADCAM systems still remain an important role among the tools for digital manufacturing and digital factory, and take a major part in interaction activities between human and computers in manufacturing industry. This situation will be strengthened further due to evolvement towards a high level of flexibility in the manufacturing industry [5]. However,

in academia and industry, it is difficult to find a generally accepted definition regarding CADCAM, and the ones in CIRP Encyclopedia [6,7] are adopted in this article, given its leading authority in this domain:

Computer-aided design (CAD) is the use of a wide range of computer-based tools that assist engineers, architects, and other designprofessionals in their design activities.

Computer-Aided Manufacturing (CAM) can be defined as the effective utilization of computers in manufacturing [8].

Current implementation of CADCAM mainly concerns functionalities of software systems, i.e. the ability to meet the users' needs. Nevertheless, a complete mixture of functions cannot simply achieve a successful engineering process for product and production development, without concern for how it works to ergonomic experiences of end users. When powerful functions are developed for sophisticated engineering activities, users often encounter troubles to

2212-8271 © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (

Peer-review under responsibility of the scientific committee of the CIRP 25th Design Conference Innovative Product Creation doi: 10. 1016/j. procir.2015.01.053

visualize, understand, and manipulate the functions through designed interaction patterns. CADCAM is supposed to simplify engineers' tasks in collecting, using, creating, and sharing information, but interface designed without consideration of usability often results in unsatisfied experiences and limited outcomes. Such issues can lead to low productivity, time-consuming training and deployment processes, unsatisfied users, and safety risks.

Thus, a way to improve performance of CADCAM systems from the viewpoint of HCI should be explored. Whether an interactive system is usable for human and to which extent the system is usable makes an important property of the system. The property is called usability and exists closely with other terms such as ease of use, user friendliness, user experiences and quality in use in different research areas. ISO 9241210:2010 [9] defines usability from the perspective of software ergonomics:

Extent to which a system, product or service can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use

From the perspective of software product [10], ISO/IEC 25010:2011 [11] adopts this definition of usability as either a subset of quality in use or a main characteristic in its product quality model. Both ISO standards agree that usability is defined as the degree of effectiveness, efficiency, and satisfaction and is affected by the operational context such as users, tasks, environment, technologies, and software interface [12]. The design of interface is merely one aspect of usability analysis [13].

To enable human-centered interactive systems, usability evaluation is a central activity to link other stages of digital product development (e.g. requirements specification, prototyping, design, and implementation) [14]. The fundamental goal of the usability evaluation is to check whether an interactive system is usable, i.e. usability requirements are reached. The evaluation can be performed by system vendors or researchers with optional participation of target users. It can happen through all stages of the product lifecycle of software systems with different purposes. A general procedure includes requirements specification, evaluation planning, conducting, data analysis, and interpretation. A delivery will include usability problems, explanation of the problems, and suggested solutions. Based on usability evaluation, design principles and guidelines can be generated for products in a certain type of context.

Especially for CADCAM, there are a plenty of existing products in use and usability evaluation can help vendors to identify problems and help users in manufacturing industry to select ideal products. It can be imagined that CADCAM brings a challenge of usability evaluation. Several researchers have identified and discussed related problems, which will be the second part of this article. A systematic view to put CADCAM under the microscope of HCI has never been reached. Therefore, the context of use of CADCAM software is analyzed in the third section. Then existing evaluation methods and the feasibility will be discussed based on found literatures in the fourth section.

2. Usability in CADCAM

Compared with other domains extensively concerned by the HCI community (e.g. web design, office productivity software, GPS-based navigation, and mobile applications), research results are very rare related to engineering activities in manufacturing industry and, more specifically, CADCAM. Most of the found literatures were published in 1980s and 1990s, when both areas are amateur and close to each other. Such publications in this highly interdisciplinary topic are usually isolated in different aspects of context, e.g., performance dimensions and user models. Accordingly, a complete picture is difficult to obtain with the limited previous work. Especially for CAM systems, usability may be the least for consideration, with more arguments on functionalities regarding information modeling, system integration, feature recognition, etc. [15] Today, an attempt of clarifying this interdisciplinary topic becomes more challenging when concepts regarding CADCAM and usability are developed deeply for half a century but independently with each other.

Still, it is easy to observe that manufacturing industry has been radically benefiting from the development of HCI. The history of computer-aided technology for engineering activities in manufacturing industry can be dated back to 1960s, when researchers in universities [16] and corporates [17] started to recognize the power of digital computing in aiding human's tasks of design and development. Afterwards, information technology plays a more and more important role in assisting human to perform more types of engineering activities. Meanwhile, the development of computer-related technology in a broader scope has changed our daily life considerably since its birth. The community of HCI devotes decades' efforts to make computers more usable and friendly in this big scope with various crucial contributions that people are taking for granted today, e.g. mouse [18], windows [19], and HyperText [20]. Desktop, mobile, and wearable devices with evolving I/O techniques are changing the ecology of HCI. Indirectly engineers also enjoy these fruitful contributions. With such relevant technologies and interactive styles, CAD is still considered as an important contribution in the history of the HCI society [21].

However, few HCI researchers have paid much attention to CADCAM and other related computer aided technologies in manufacturing industry. The neglect is reasonable due to a relatively small group of users and a considerably high requirement on knowledge compared with other application domains. For projects applying usability evaluation in such a complex domain, Chilana, et al. [22] pointed out that the key challenge was a lack of domain expertise related to the complex systems, which made managers and developers reluctant to trust usability experts. A significant phenomenon is that software vendors tend to trust customers rather than usability experts [23]. Hence, it is recommended for a project with a focus on usability evaluation to collaborate with manufacturing companies in this area.

A limited number of researches presented issues and solutions on the ergonomic perspective of CAD systems. Luczak et al. proposed their opinions on ergonomics in CAD systems in two editions [24,25], which implied a substantial

distinction of engineering activities due to its characterization as mainly in a higher level of cognitive control in informatory work, i.e. knowledge-based processes [26]. Such processes may frequently involve problem-solving and decision-making activities which fundamentally differ from rule-based and skill-based processes. A basic demand for the extensive knowledge-based processes is that the design of interaction should be cognitively compatible with users' mental model, e.g. features representing chunks as information clusters to form engineers' knowledge [27]. In the CIRP community, Hatvany and Stone expressed their concerns about user friendliness of CAD systems in 1987 [28]. Most of the proposed principles for CAD were coincidentally included in the Nielsen's heuristics [29,30], but were also specialized for engineering tasks. Visibility of system status, freedom of user controls, flexibility, and efficiency were prioritized in the CAD based research, especially when it came to usage of manuals, sensitivity analysis, and impasses [28].

According to [31], Buxton [32] proposed a five-layer model to describe a classification problem domain of HCI studies: conceptual, semantic, syntactic, lexical, and pragmatic. Traditional usability studies have been usually conducted with the focus on the latter three levels, i.e., syntactic, lexical, and pragmatic, which was attacked by Albers, M. [33] as insufficient for complex information systems where the conceptual and semantic layers dominated the overall performance. When software such as CADCAM is developed and used for complex tasks, usability experts may find that it is convenient to divide a complex system/task into components/subtasks and only investigate them individually. Assumptions have to be made that a set of usable components indicates a usable system. Adequacy of such assumptions has been argued by [34-36]. A high diversity of task paths makes it impossible to achieve a comprehensive understanding or prediction of the interaction patterns [37]. Hence, in the semantic and conceptual layers, Albers [33] required usability studies' focus on reasoning of path selection, predicting unusual scenarios [38], avoiding overloaded information [39], handling mental models [40], and delivering contextual awareness [41].

3. Context of use for CADCAM systems

In the field of HCI, usability should never be treated as an intrinsic property of interactive systems. An entire context of use should be observed, analyzed, and tuned to achieve an acceptable level of usability and, eventually, an acceptable level of user experience [42]. Fig. 1 illustrates basic elements of interaction activities. For end users and other types of stakeholders, the user interface (UI) is equivalent to these types of interactive digital systems [43]. Therefore, interface designers should focus on fitting the interactive system into the context where it is operated [44]. The following part will review relavant studies and discuss the operational characteritics of users, knowledge, tasks, interaction, and environment separately in the particular context of use.

System Output


Device, software, Information model

Interactive system

Fig. 1. Forthe users, UI is the systems (modified based on [43,44])

A major element of this context is users and knowledge they possess, which makes CADCAM significantly different from common software or web applications that usability experts usually handle. In such a complex domain, HCI studies suffer from domain-specific terminology, unique situations, limited access to expertise, reluctance to external professionals, etc. [22] Rasmussen [26] categorized human behaviors into three levels: skill-, rule-, and knowledge-based behaviors, and identified that issues relating to skills and rules were typically in HCI studies' care, while knowledge-based behaviors was a significant research gap for complex domains. The behavior patterns can be easily mapped to a theory of knowledge continuum (Fig. 2) [45,46]. In this continuum, expertise knowledge is most specific, related with professions, and used least frequently. Ideally, lower levels of the continuum should be recommended so that a lower level of users' cognitive loads can be guaranteed during interaction. Meanwhile, usability experts can easily evaluate, analyze and design for any software domain when less specific knowledge dominates interaction. However, during engineering activities, usage of domain-specific expertise knowledge cannot and should not be avoided, especially for convenience of experienced users [47]. It is reasonable because most aids from computers still act similarly to their ancestors (i.e. paper and pen), as recorders for solutions [48]. Major functions of CADCAM coincide with what can be observed by traditional design sketches: external memory, association with non-visual information, and physical settings of the design results [49]. Accordingly, design of IT systems should take into account the traditional cognitive situation of engineers and reach a balance in multiple levels of the knowledge continuum.

Source of acquisition

Frequency of exposure

Fig. 2. Continuum of knowledge (modified based on [45])

Design process Manufacturing process

Synthesis Analysis CAM process

CAD process

Requirements specification | Production |

Feasibility I study Conceptual 1 design Quality control Marketing

Production planning Tooling Preparation Ohlcr ol' material NC programming t Process planning

I 1 T

Modelling& simulation Design analysis | Packaging I l Shipping

t optimization | Design evaluation i Datura filiation &

Fig. 3. Tasks performed with CADCAM systems (modified based on [7,53])

Today, CADCAM software is executing core tasks of information systems for digital factory and digital manufacturing. In academia of manufacturing engineering, many definitions are given for information systems providing digital preparation of products and production, e.g. engineering information systems [50], Computer Integrated Manufacturing (CIM) [51], and virtual product development

[52]. Precise unification cannot be reached to clarify the terminology, which leads to a wide diversity when it comes to the categorization of numerous CAx (Computer-Aided technology) software systems, e.g. CAD, CAM, CAE (Computer-Aided Engineering), CAPP (Computer-Aided Process Planning), and CAQ (Computer-Aided Quality assurance). One typical example of the roles of CADCAM with brief description of relevant tasks was provided by Zeid

[53], which identified a broad scope even including tasks of many other kinds of CAx systems defined by academia (Fig. 3).

No matter with CAD or CAM, interaction has roots in traditional design activities which are a center part of engineering tasks. Psychologists have been studying patterns of design processes for decades. "Problem-solving" cannot simply represent all kinds of related intellectual behaviors of engineers [54]. Moreover, a structured design process cannot guarantee a successful solution, while a flexible methodical style was recommended by experienced mechanical designers [55]. McNeill [56] confirmed a generally accepted engineering design process consisting of a cycle of analysis, synthesis, and evaluation, but the three types of activities are distributed flexibly according to the progression stage. Such behavior classification can be simply mapped to a triple-mode pattern that is critical for novel decision: drawing, examining, and thinking [57]. Rapid shifts between the modes were radical to reach breakthrough decisions [57,58], and therefore require strong supports from software.

The environment, in terms of organizations and technology, may be the least to consider, but still need to be deliberated by designers of CADCAM. A phase-oriented task allocation (Fig. 3) is a key driver of CAx software for manufacturing industry where digital technology is required to keep information available, manageable, and integrated [25]. CAD as a center software system for engineering design has been explored thoroughly in terms of e.g. product lifecycle, mass production,

information flows, and enterprise hierarchy [59]. On the other hand, CAM as a bridge between design and manufacturing is also a center of related processes, knowledge, and technology. The both CAx domains should be integrated seamless [60] while also working closely with other technology domains e.g. equipment acquisition and factory design [61].

4. Evaluation techniques and feasibility in CADCAM

In research areas of HCI and software engineering, the general requirements of usability are formally documented by the related standards (see Section 1). Based on the standards, Quesenbery's 5 E's [62] raised dimensions of usability that should be concerned during evaluation: Effective, Efficient, Engaging, Error tolerant, and Easy to learn. These dimensions guide understanding of requirements and establish a foundation of usability evaluation. Evaluation techniques will be selected, planned, interpreted based quantified or qualified requirements, and finally, guide a design to reach desired performance levels in all the dimensions.

A large number of evaluation techniques for interactive systems have been developed since 1980s. There are various theories on classifications of these techniques, but no one is widely accepted [63]. Most of the classifications are based on [64], according involvement of users and computers (Fig. 4). Development of heuristic evaluation methods [29] and modelbased methods (e.g. [65,66]) extends the classification to several new editions [67,68]. Comparisons of usability evaluation techniques [69,70] draw a conclusion which makes the precise classifications not so important: combination of techniques applied at different stages is the best choice. Another conclusion is that proficiency of evaluators in both HCI and task domains is important to identify usability problems of target software [67].

It is a critical decision whether or not to involve participation of users in the evaluation, which leads to two major types of evaluation techniques: user observations and interface inspections. Involvement of users is preferred by most evaluation projects. However, as a part of an iterative product development process, usability evaluation is likely to be performed frequently. Cost of resources and time cannot be afforded if enough users are involved every time. Moreover, before conducting any types of user observations, pilot inspections in-house are recommended to ensure success of formal evaluation sessions.

~3 Representational. Real

r \ Analytic methods f \ User reports v y

f Specialist reports r S Observational methods v J

Fig. 4. Classification of evaluation methods [63]

As expected, most of the related studies involve users to evaluate interface and tasks in practice. Ullman [71] directly recorded manual engineering activities to generate seventeen goals of CAD systems. Participants in a collaborative 3D CAD environment were directly observed by Nam and Wright [72], and an additional questionnaire was employed for subjective description of user experiences, which positively supported the proposed collaborative CAD environment by quantified user testing results. In another collaborative context, Ahn et al. [73] used questionnaires as a major means to collect usability data to prove web-based UI outperforming CAD-based tools in accessibility. Sung et al. [48] adopted an indirect observation technique, i.e. logging designer behaviors with CAD systems to achieve knowledge management. The importance of knowledge capture and knowledge capitalization was further supported by Molcho et al. [74], where feedback forms from industry were adopted as a major part of the proposed rule base for manufacturability analysis.

Evaluation techniques without users' participation are also a reasonable choice with advantages such as shorter duration, lower cost, and flexible processing. Heuristic assessment was chosen by Ficarra and Rodriguez [75] for easing learning process of CAD in textile industry. Lee et al. [76] adopted a two-stage evaluation method with a focus on interface inspection by experts. Based on surveys on a large number of novices, experienced experts in usability and 3D engineering were asked to evaluate existing CAD systems and to generate new design principles specified for this domain.

5. Conclusion

Engineers are requested to excel in complex engineering tasks with complex domain knowledge, which makes great difficulties from a novice to an expert [77]. Meanwhile, they have to be skilled with all kinds of functions of CADCAM. Hence, the widely-existing complexity in domain knowledge, tasks, and technology delivers limitations in various dimensions of usability, e.g. efficiency, learnability, and engaging [78]. This situation is compromising user experiences and decreasing productivity in practice.

Concerned with software usability, HCI methodology should be fully explored to improve the performance of CADCAM in manufacturing industry. This paper reviews related publications, analyzes operational context, and discusses existing evaluation techniques in manufacturing industry. Given the trend of digitalization in manufacturing systems, research in this interdisciplinary domain should be carried out with an extensive scope and depth.

Pragmatic issues are also investigated in this paper. Usability studies are usually performed closely with software vendors. In practice, software developers are reluctant to communicate with usability professions, compared with customers' voice. Hence, these types of studies are recommended to be taken by software users. Besides, a high level of proficiency in the domain knowledge is the key to a good result. Moreover, manufacturing companies often have difficulty to select IT products. Evaluation independent of IT vendors will be useful for the customers to select suitable products and for the vendors to address suggestions.


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