Industrial workstation design: a systematic ergonomics approach

For the design of an industrial workstation, ergonomics guidelines are presented in a systematic manner. The guidelines provide a conceptual basis for a good workstation design. In a real world design situation, the implementation of the recommendations or guidelines needs the matching of the population anthropometry with the various components of the workstation. Adequate posture, work height, normal and maximum working areas, lateral clearance and visual requirement are determined for the intended user population. The procedure for determining the workstation dimensions and layout has been explained. The importance of building a mock-up of the designed workstation and its evaluation with representative subjects is emphasized. A case problem (supermarket checkstand workstation) is discussed to illustrate the workstation design procedure.     

Principles of work system performance optimization: A business ergonomics approach

Recently, there has been a growing interest in optimizing performance in the workplace. This interest is stimulated not only by economic and competitive pressures, but also by a growing awareness of the need to improve health and safety, thereby improving workplace wellness and vitality and, in turn, productivity. This article reviews the contributions of traditional approaches to work system performance optimization. These approaches include scientific management, work-time studies, industrial psychology, ergonomics, human factors, industrial engineering, total quality management, kaizen theory, systems theory, and operations research. The benefits, features, and drawbacks of each approach are discussed and tabulated. A basis for a new comprehensive methodology of work system performance optimization called the business ergonomics approach is then outlined and presented. © 1999 John Wiley & Sons, Inc.     

Snap-on-handles for a non-powered hacksaw: An ergonomics evaluation,redesign and testing

In this study, we investigated how experienced and inexperienced subjects handle a box when it could be approached from any of its sides. Subjects moved a box (11 kg) either to a high (HS) or a low surface (LS). Wrist movements and grip force were synchronised and recorded, respectively, by electrogoniometers and an instrumented box. All subjects adopted a lateral-and-bottom grip, with parts of the hands simultaneously placed on the side and bottom of the box. This grip allowed the 50th percentile of wrist movements to be within safe limits, particularly in the sagittal plane. Low force was associated with lowering the box to LS and equally distributed but greater force when lifting to HS. Larger ulnar deviation was recorded when the box was lifted to HS. Only peak of wrist extension differentiated experienced from inexperienced subjects, with experienced presenting larger wrist extension. Alternative box designs are suggested to improve handling in real settings. PRACTITIONER SUMMARY: Understanding worker preferences for box lifting behaviour can contribute to the development of new designs that facilitate the adoption of more efficient postures while reducing the risk of upper-limb musculoskeletal disorders and promoting safer manual material handling.     

Snap-on-handles for a non-powered hacksaw: an ergonomics evaluation, redesign and testing

Based on the ergonomics evaluation of existing non-powered hacksaws with original/horizontal and conventional/market handles, ergonomically designed hacksaw handles are proposed. To accommodate the entire male and female populations, the hand dimensions are categorized into three groups: small, medium and large. The proposed handles give special emphasis to hand size, length, cross-section dimension and curvature. The three-sized handles for both the preferred (rear) and non-preferred (front) hands are interchangeable to suit the individual hand size. Thus, the concept of 'snap-on-handles' with a fixed hacksaw (blade) can be promoted. The ergonomically designed hacksaw handles were tested/compared with original/horizontal and conventional/market hacksaw handles, in terms of performance or productivity (depth of cut), muscular effort or strain (EMG) and subjective scores (acceptance/comfort). The experimental results conclusively proved that the ergonomically designed hacksaw handles were significantly better than the other handles in terms of the stated criteria. The performance or productivity improvements of the ergonomically designed handles were about 25 and 148%, when compared with the conventional/market and original/horizontal handles, respectively. Furthermore, when the ergonomically designed handle was not matched with the proper or appropriate hand size, there was a significant reduction in performance or productivity, increase in muscular effort and decrease in subjective scores of acceptance/comfort.     

A systematic approach for robust repetitive controller design

In this paper, a methodology for the synthesis of repetitive controllers to ensure periodic reference tracking and harmonic disturbance rejection is cast in a robust control framework. Specifically, the Lyapunov–Krasovskii theory is applied to derive LMI-based conditions for designing a state feedback control law with guaranteed stability and performance properties for system parameter variations. Practical experiments in commercial uninterruptible power supplies – UPS are considered to illustrate and discuss some practical implementation aspects of the proposed method.     

Development work for quality and ergonomics

Employee participation in the development and improvement of their own work activities and daily production tasks has been strongly emphasised by the “quality movement”. From this point of view, the quality perspective, and in particular development work, are supportive of improved working conditions and ergonomics. This paper proposes a classification of development work in relation to participative problem solving. Further, the introduction of development work was found from a theoretical point of view to be consistent with improvement in the characteristics that represent good and rewarding work. Several empirical studies in the field confirm that improvements in work and company performance take place as a result. There is also criticism of development work, which largely focuses on the difficulties of integrating such concepts into organisational structures and of making developments long-lasting. In addition, stress, intensification of work and increased pressure are also mentioned as possible harmful outcomes. It is concluded that the development work concept is an important innovation with great potential, but the organisational models and applications need to be further developed for the future.     

Task design, psycho-social work climate and upper extremity pain disorders--effects of an organisational redesign on manual repetitive assembly jobs.

A company redesign was carried out to improve production efficiency and minimise the prevalence of work-related musculoskeletal disorders and sick leave. The redesign was evaluated on the basis of studies of assembly workers before (17 workers) and after (12 workers) the redesign. The redesign resulted in more varied, less repetitive, and more autonomous assembly jobs. The psycho-social work climate was both improved and impaired. A medical examination showed that eight of 17 workers before and nine of 12 workers after the redesign suffered from upper extremity pain disorders. Neither the production goals nor the goals of the redesign were fulfilled. Our conclusion was that the increased task variation and impaired psycho-social work climate, combined with a lack of skill and competence, actually increased the physical stress, risk for disorders and difficulties in fulfilling the production goals.     

An ergonomics approach to refrigerator design for the elderly person

The objective was to determine a set of refrigerator design guidelines for independent living elderly women. The study was conducted with a refrigerator mockup with interchangeable internal features. Twelve elderly women participated, both in a standing and seated (wheelchair) position. The participants were videotaped as they simulated use of shelves and drawer, and they rated these components and their positions for acceptability of reach, visibility of contents, and personal preference. Participants then used a variety of mockup items to configure the refrigerator to their own preferred design. These were then analysed and synthesised into three 'consensus' designs combining the features of most of the others.     

A framework for performing workplace hazard and risk analysis: a participative ergonomics approach

Despite the unanimity among researchers about the centrality of workplace analysis based on participatory ergonomics (PE) as a basis for preventive interventions, there is still little agreement about the necessary of a theoretical framework for providing practical guidance. In an effort to develop a conceptual PE framework, the authors, focusing on 20 studies, found five primary dimensions for characterising an analytical structure: (1) extent of workforce involvement; (2) analysis duration; (3) diversity of reporter role types; (4) scope of analysis and (5) supportive information system for analysis management. An ergonomics analysis carried out in a chemical manufacturing plant serves as a case study for evaluating the proposed framework. The study simultaneously demonstrates the five dimensions and evaluates their feasibility. The study showed that managerial leadership was fundamental to the successful implementation of the analysis; that all job holders should participate in analysing their own workplace and simplified reporting methods contributed to a desirable outcome.

Practitioner summary: This paper seeks to clarify the scope of workplace ergonomics analysis by offering a theoretical and structured framework for providing practical advice and guidance. Essential to successfully implementing the analytical framework are managerial involvement, participation of all job holders and simplified reporting methods.     

The ergonomics lab: a practical approach

Abstract

Abstract. This article is concerned with methods and experiences in usability testing of standard application business software. In order to achieve the multiple trade-off between scientific objectivity, practical applicability, and the cost-benefit ratio, a set of standard methods and the resulting testing environment in the ergonomics lab are described and demonstrated by examples. Stumbling blocks are discussed. Necessary additional prerequisites for a successful practical approach are stressed.     

ARREST: From work practices to redesign for usability

In this paper we discuss the redesign of a support management system deployed in a small and medium sized enterprise (SME) in the UK. The original system was not fulfilling its needs as it had not captured work practices in a way that was recognizable to the users. The advantages of the redesign included: improved usefulness; improved efficiency and productivity; reduced learning time; improved usability; and increased acceptance among users. The system is used to support complex and distributed cooperative activities taking place in an SME. We evaluated the current system and analysed work practices using a user-centred design and evaluation philosophy. In this paper we discuss how user needs are incorporated into the enhanced design of the support management system. The user-centred design techniques used in this research include interviews, questionnaires, observations and user tests. We present comparative evaluation results that show significant improvement in performance of user tasks using the redesigned support management system. The contribution of this paper is the presentation of a case study to show how a user-centred design and evaluation philosophy can lead to better requirements capture resulting in systems that more accurately capture the users’ conceptual models.     

Continuous-time controller redesign for digital implementation: A trajectory based approach

Given a continuous-time nonlinear closed loop system, we investigate sampled-data feedback laws for which the trajectories of the sampled-data closed loop system converge to the continuous-time trajectories with a prescribed rate of convergence as the length of the sampling interval tends to zero. We derive necessary and sufficient conditions for the existence of such sampled-data feedback laws and—in case of existence—provide explicit redesign formulas and algorithms for these controllers.     

An ergonomics approach for work in the next millennium in an IT world

This article begins by giving the background to different the approaches in trying to predict what the labour market will look like in the future. Ongoing changes in the labour market are then discussed, together with their consequences in the slightly longer term. We then look at various ways in which we can steer changes in the labour market into a direction desirable to both society and the workforce. Finally, the needs for new research are reviewed, followed by some concluding remarks.     

An ergonomics approach for work in the next millennium in an IT world

This article begins by giving the background to different the approaches in trying to predict what the labour market will look like in the future. Ongoing changes in the labour market are then discussed, together with their consequences in the slightly longer term. We then look at various ways in which we can steer changes in the labour market into a direction desirable to both society and the workforce. Finally, the needs for new research are reviewed, followed by some concluding remarks.     

Computer-aided ergonomics: a case study of incorporating ergonomics analyses into workplace design

One of the primary goals of computer-aided ergonomics is to develop software tools that allow ergonomics information to be accessed at the earliest stages of design. This case study discusses a PC-based software program that allows a designer to quantify a worker's biomechanical risk for injury based on a proposed workplace design. The program couples an established software tool for biomechanical analysis, the Three-Dimensional Static Strength Prediction Program (3DSSPP), with a widely used computer-aided design software package, AutoCAD. The use of this "3DSSPP/AutoCAD interface" in the proactive analysis of an automotive assembly task is described and the results compared with an independent assessment using observations of workers performing the same task. Both studies yield similar conclusions, suggesting that proactive use of software such as the 3DSSPP/AutoCAD interface may be a valid tool in evaluating proposed workplace designs. In this context, issues in the analysis of workplace designs regarding the use of supporting ergonomic tools, assumptions, and posture selection are discussed.     

A hierarchical approach for the redesign of chemical processes

An approach to improve the management of complexity during the redesign of technical processes is proposed. The approach consists of two abstract steps. In the first step, model-based reasoning is used to generate automatically alternative representations of an existing process at several levels of abstraction. In the second step, process alternatives are generated through the application of case-based reasoning. The key point of our framework is the modeling approach, which is an extension of the Multimodeling and Multilevel Flow Modeling methodologies. These, together with a systematic design methodology, are used to represent a process hierarchically, thus improving the identification of analogous equipment/sections from different processes. The hierarchical representation results in sets of equipment/sections organized according to their functions and intentions. A case-based reasoning system then retrieves from a library of cases similar equipment/sections to the one selected by the user. The final output is a set of equipment/sections ordered according to their similarity. Human intervention is necessary to adapt the most promising case within the original process.     

Standards for ergonomics principles relating to the design of work systems and to mental workload

Starting with some recent developments in standardization in the field of ergonomics principles relating to the design of work systems, an overview is given on standards and ongoing activities in this field, pointing to problems and perspectives, especially in the context of the activities of the different standardization committees. Existing international standards relating to mental workload are described, together with possible future developments in this area.     

A new intelligent digital redesign for T-S fuzzy systems: global approach

This paper proposes a novel and efficient global intelligent digital redesign technique for a Takagi-Sugeno (T-S) fuzzy system. The term of intelligent digital redesign involves converting an existing analog fuzzy-model-based controller into an equivalent digital counterpart in the sense of state-matching. The proposed method should be notably discriminated from the previous works in that it allows us to globally match the states of the overall closed-loop T-S fuzzy system with the predesigned analog fuzzy-model-based controller and those with the digitally redesigned fuzzy-model-based controller, and further to examine the stabilizability by the redesigned controller in the sense of Lyapunov. The key idea is that the global intelligent digital redesign problem is viewed as a convex minimization problem of the norm distance between nonlinearly interpolated linear operators to be matched. Sufficient conditions for the global state-matching and the stability of the digitally controlled system are formulated in terms of linear matrix inequalities (LMIs). A complex nonlinear system, Duffing-like chaotic oscillator is simulated and demonstrated to validate the feasibility and effectiveness of the proposed digital redesign technique, which implies the safe applicability to the digital control system.