Isoresponse time regions for the evaluation of visual search performance in ergonomic interface models.

Computer-aided ergonomic evaluation models often provide a limited function of visual performance, usually in the form of visibility tests at any given location. It is, however, of great importance to complete a visual task in a predetermined time successfully or to predict the time to complete the task, e.g., a task of high-level control such as aircraft flight operations. In this study, isoresponse time regions which have an effect on visual performance in real-life situations are presented as an effort to complement aforementioned shortcomings of ergonomic interface models. A multiple regression was used to provide equal response time regions, being asymmetrical in shape. In addition, the fuzzy linear regression (FLR) model was introduced to provide a fuzzy set from which a decision-maker might select appropriately. It provided similar fitted values with having the advantage of utilizing the interval of those fitted values over the conventional regression model. The results can be applied effectively to the design of an interface for diverse visual tasks in real situations.     

Visually deficient working conditions and reduced work performance in office workers: Is it mediated by visual discomfort?

IntroductionThe main purpose of this cross-sectional study was to investigate whether visual discomfort acts as a mediating factor between perceived visual ergonomic working conditions and self-rated visual performance among office workers who carry out administrative tasks and computer-based work at the Swedish Tax Agency.MethodsA questionnaire was sent to 94 office workers addressing: 1) perceived visual quality of the visual display units; 2) prevalence of eye symptoms; and 3) self-rated visual performance. Eighty-six persons (54 women (63%), 31 men (36%), and 1 of unspecified sex) answered the questionnaire. Multiple regression analysis investigated the association between visual ergonomic working conditions and visual performance, both with and without visual discomfort as a mediator.ResultsThe group mean of the Indexed survey questions indicated a reasonably good quality of visual ergonomic working conditions, a relative absence of eye symptoms, and acceptable self-rated visual performance. Results from multiple regression analysis showed a significant association between perceived visual ergonomic working conditions and self-rated visual performance (r² = 0.30, β = 0.327, p < 0.01). When visual discomfort was used as a mediator, the association between perceived visual ergonomic working conditions and self-rated visual performance remained the same (r² = 0.32, β = 0.315, p < 0.01).DiscussionIt was remarkable to discover that self-rated visual performance was independent of visual discomfort. Possible explanations include exposure factors not included in the current study, such as dry air and sensory irritation in the eyes, psychosocial stress, time spent performing near work activities, or time exposed to visually deficient working conditions.Relevance to industryThe strong connection between satisfaction with visual ergonomic working conditions and productivity in this study has implications for workplace profitability and staff satisfaction. If productivity is enhanced by better visual ergonomic working conditions, then managers of workplaces may be able to improve work outcomes by optimizing the physical work environment.     

Design aspects of the Burroughs ET 1100 ergonomic workstation

The Burroughs ET 1100 ergonomic workstation is a general purpose data communications system composed of a display unit and a cable-connected keyboard. It is intended for use in full-time work or continuous-use situations, therefore every effort was made to take ergonomic considerations into account. This paper describes the design process, the limitations provided to the design staff and the resulting product which was released in April 1983. A number of interacting variables needed to be balanced to ensure that one feature had not been optimized to the detriment of another. In addition to the manufacturers interest in the product it was important that it be installed properly, therefore additional measures were taken to educate users and managers about desirable environmental characteristics.     

A Study of Computerized Offices in Greece: Are Ergonomic Design Requirements Met?

In this study, an investigation was conducted into the extent to which ergonomic requirements for work on computers are met in Greek office workstations. The ergonomic requirements considered were those included in Council Directive 90/270/EEC (1990) of the European Union and the ISO 9241 (1997) standard. 593 office workstations were assessed using an assessment tool consisting of 70 assessment points. The assessment results show that the ergonomic requirements that are independent of the specific characteristics of individual work spaces and environments (e.g., design standards for seats, monitors, and input devices) are adequately met. Ergonomic requirements that should take into consideration the specific characteristics and constraints of individual work content, work spaces, and environments (e.g., requirements dealing with workplace layout, environmental conditions, software, and work organization) are inadequately met. Based on these results, issues are indicated on the effort ergonomists should focus to improve working conditions in computerized offices.     

Design aspects of the Burroughs ET 1100 ergonomic workstation

Abstract

The Burroughs ET 1100 ergonomic workstation is a general purpose data communications system composed of a display unit and a cable-connected keyboard. It is intended for use in full-time work or continuous-use situations, therefore every effort was made to take ergonomic considerations into account. This paper describes the design process, the limitations provided to the design staff and the resulting product which was released in April 1983. A number of interacting variables needed to be balanced to ensure that one feature had not been optimized to the detriment of another. In addition to the manufacturers interest in the product it was important that it be installed properly, therefore additional measures were taken to educate users and managers about desirable environmental characteristics.     

Ergonomic design of large forestry machines

Since 1967, the ergonomic design of large forestry machines has been the subject of continuous study. Ergonomic guidelines have been developed and successfully introduced to the manufacturers of the machines and to the forest industries.

Manufacturers have implemented comprehensive ergonomic improvements. Operator workspace, visibility, lighting, operator's seats, mounting and alighting, cab climate, and service of machines have been improved. Noise and vibration levels have been reduced. The risk of accidents is slight. In many respects, the ergonomic standard is now good.

Increasing mechanization is posing new problems, however. Operators of forestry machinery are being afflicted by overload injuries to the neck, arms, and cervical spine. The main causes of these injuries are probably excessive periods of sitting, excessive work intensity during work in fixed, ergonomically inappropriate positions, and repetitive, short-cycle movement patterns. Ergonomic improvements in equipment design (particularly controls) and work organization are proposed in this report.     

Accessibility and ergonomic analysis of assembly product and jig designs

In the aircraft industry, the design of floor assembly jigs (FAJs) is an important activity that directly affects productivity. It involves tool frame generation and locator and clamp placement to ensure that the assembly components are held properly with respect to each other to meet the required tolerances. The tool designer also has to analyze the design to ensure that the assembly process does not pose accessibility and ergonomics related problems. The current approach is dependent on the experience of the tool designer and the limited visualization possible on commercial CAD systems. This leads to extensive redesign when accessibility and ergonomic related problems are detected on the physical prototype. In this research, an integrated Virtual Reality-based environment is being developed for the analysis of assembly product and jig designs. CAD models of the assembly product and jig are imported into a Virtual Reality (VR)-based visualization system for accessibility analysis. A motion tracking system is integrated to allow ergonomic posture analysis. The combined VR and motion tracking system allows evaluation of alternate assembly sequences and the jig design. In this paper, the theoretical basis for the analysis environment is presented along with details of the prototype implementation of this system.

Relevance to industry

Floor assembly jigs are used extensively by the aircraft industry. Improvement of their design process will lead to savings in better design and reduced development time and cost. Better designs will require fewer changes after the jigs have been fabricated. The overall result will be a reduction in product realization time and cost and improved product quality.     

Planning and implementation of microscope work

In modern electronics manufacturing, many of the assembly operations require the use of microscopes. This paper presents measures and suggestions that could help in relieving visual and postural fatigue in microscope work. These measures include the ergonomic design of microscope workstations as well as of microscopes themselves, process changes to minimise use of the microscope, replacement of microscope workstations with television systems, and a training programme for inexperienced operators. The main emphasis in implementing these recommendations was the ergonomic design of microscope workstations; several examples are given.     

Visual impact analysis: a case study of a computer-based system

A system for computer-aided visual impact analysis (CAVIA) has been developed. The system can be considered as having landscape data, object data, visibility and visualization subsystems. A case study of the application of the system to the evaluation of alternative transmission line routes illustrates the techniques used for data collection, visibility and visualization. The integration of a digital terrain model (DTM) and associated derived data with Landsat satellite data to guide design work and construction planning is described. Validation of visualization and other aspects of the technique based on the constructed lines and current and future developments such as image mixing are discussed. The need for the system as an aid to planning and design problems is explained.     

A Reply to “ Comments on ’ Cardiac Frequency in Relation to Aerobic Capacity for Work ’ ”

An animated-film sequence simulating the significant visual aspects of a vehicular trip on a projected but nonexistent airport road system was produced in order to provide a direct, essentially realistic, and immediately comprehensible means of s ‘experiencing ’ the process of data perception and response required in negotiating the road system safely and accurately to a selected destination. The film objectively and incontrovertibly confirmed the existence of a problem caused by a suspected ergonomic defect in the road-system design. It seems unlikely that such could have been confirmed to the satisfaction of all concerned by the use of any other method before the actual road system was completed and its negotiation could be experienced in situ. The history of this project suggests that film-animation simulation can be a valuable design tool in situations where the fourth dimension is an important factor. Further, it suggests that live-action film of existing situations can be a more valuable aid in analysing and correcting design defects than has been generally appreciated.     

人机系统中视域评估的可视化

为了达到视域评估的可视化效果,文中构建了人眼可视范围的半透明模型,并绑定到虚拟人的骨骼中,通过驱动虚拟人,以实时混合绘制技术完成动态视域评估。以龙门式数控加工中心造型设计模型为对象进行实例仿真,结果表明逼真的可视化效果使得视域评估变得简单、快捷和直观,避免了大量的人工运算,提高了视域评估的速度、降低了人为失误。该方法可直接面向工程的实际应用,满足各类布局设计的可视化评估要求。     

Applying psychophysics to prevent overexposure: On the relationships between acceptable manual force,joint loading,and perception

Psychophysical methods are commonly used to establish guidelines for task acceptability or to indicate perceived task demands. Despite their widespread use and practical application, the subjectivity of psychophysical methods can limit their perceived benefit to field ergonomists and engineers. However, recent work has revealed important links between biomechanical limitations and psychophysical force acceptability and also between perceived effort and moment loading at the shoulder. These twin findings support the continued use of psychophysical methods in ergonomics, and implore future developments to improve their use in the field. Through a combination of literature review and research vignettes, these links are described, discussed, tested and applied in both experimental and simulation scenarios. Whether the goal is to design work based on psychophysically acceptable guidelines, or to gauge existing task demands using perceived effort, this paper highlights the power of psychophysics for ergonomic design.     

VLOD: high-fidelity walkthrough of large virtual environments

We present visibility computation and data organization algorithms that enable high-fidelity walkthroughs of large 3D geometric data sets. A novel feature of our walkthrough system is that it performs work proportional only to the required detail in visible geometry at the rendering time. To accomplish this, we use a precomputation phase that efficiently generates per cell vLOD: the geometry visible from a view-region at the right level of detail. We encode changes between neighboring cells' vLODs, which are not required to be memory resident. At the rendering time, we incrementally construct the vLOD for the current view-cell and render it. We have a small CPU and memory requirement for rendering and are able to display models with tens of millions of polygons at interactive frame rates with less than one pixel screen-space deviation and accurate visibility.     

Fuzzy logic-based decision support system for automating ergonomics risk assessments

Workers in the modular construction industry are frequently exposed to ergonomic risks, which may lead to injuries and lower productivity. In light of this, researchers have proposed a number of ergonomics risk assessment methods to identify design flaws in work systems, thereby reducing ergonomic discomfort and boosting workplace productivity. However, organizations often disregard ergonomics risk assessments due to a lack of convenient tools and knowledge. Therefore, this study proposes a fuzzy logic-based decision support system to help practitioners to automatically and comprehensively assess the ergonomic performance of work systems. For comprehensive assessment of ergonomic risk, the proposed decision support system considers physical, environmental, and sensory factors. Specifically, the decision support system comprises eight fuzzy expert systems that output a composite risk score, called an “ergonomic risk indicator”, that indicates the overall level of ergonomic risk present in a given work system. The performance of the proposed decision support system is then evaluated using a real-world case study in a modular construction facility by comparing the results of the decision support system with the facility's occupational injury reports. The results prove the effectiveness of the decision support system. Overall, the decision support system is capable of generating a composite risk score, the ergonomic risk indicator, and the proposed high-level architecture and design represent significant contributions for the enhancement of health and safety in the modular construction industry.     

An ergonomic evaluation of manual Cleco plier designs: effects of rubber grip, spring recoil, and worksurface angle

The present study evaluated two design modifications (rubber grip and torsion spring) to the conventional manual Cleco pliers by electromyography (EMG), hand discomfort, and design satisfaction. This study also surveyed workers' satisfaction with selected design features of the pliers for ergonomic improvement. A two-way (plier design x worksurface angle) within-subject (nested within gender and hand size) design was employed. Eleven workers simulated the plier task in an adjustable workstation for different plier designs and worksurface angles (0 degrees , 60 degrees , and 90 degrees ). Lower EMG values were obtained for the pliers with rubber grip and at 60 degrees of worksurface angle. EMG values varied significantly between the participants, but showed low correlations (Spearman's rank correlation = -0.27 approximately -0.58) with their work experience with the pliers. The hand discomfort and design satisfaction evaluations identified that the grip span (max = 14.0 cm) and grip force requirement (peak = 220.5 N) of the current pliers need ergonomic modification. The present study shows the needs of both the ergonomic design of a hand tool and the training of a proper work method to control work-related musculoskeletal disorders at the workplace.     

Video display terminals and vision of workers Summary and overview of a symposium

This summary discusses issues raised at a National Research Council symposium on vision and VDT work, held at the request of the National Institute for Occupational Safety and Health. Symposium participants critically reviewed laboratory studies of visual function and field surveys of visual complaints of VDT operators to determine what conclusions can be drawn about the prevalence, severity, causes of, and possible remedies for reported difficulties. Although speakers' perspectives differed, a number of points appeared to gain consensus: (i) properly designed epidemiologies) studies comparing the incidence of visual problems in VDT operators with that in non-VDT workers are needed, (ii) Visual issues are closely interrelated with ergonomic and job design variables, and use of multivariate statistical analysis is necessary to determine what specific aspects of work involving VDTs may contribute to visual and other complaints, (iii) No scientifically valid study has established that VDT use causes harm, in the sense of damage, to the visual system, (iv) Existing knowledge indicates a number of measures that could be taken to improve worker comfort and performance: use of high-quality displays; control of workplace lighting conditions; application of principles of anthropometric design; and consideration of workers' needs in design of jobs, (v) Surveys of radiation emissions from VDTs indicate that levels of radiation are far below U.S. occupational exposure standards. Published data provide no evidence that cateracts are associated with VDT use. (vi) Standards should be based on research. Differing opinions on whether setting standards is useful and appropriate point to the need for caution in this area. Needs for further research were identified.     

Corporate ergonomics programme at automobiles Peugeot-Sochaux

An ergonomic assessment tool for design procedures, exclusive to Peugeot-Citro?n, called ECM, was developed and applied at the design stage by method technicians in the 1990s. It generates data, which are followed up by the project leader of a new model and ergonomists until two years before each launch. During this time, vehicle design is subject to modification, to adapt to ergonomic demands. Simplified methods (DACORS and METEO) were also developed to assess workstations on the shop floor in trim and final plants. Assessments were used to grade the workstations into four profiles linked to physical and static requirements. Production technicians are responsible for the application of these local methods on the shop floor. The management of these centres aimed to reduce the risks of musculoskeletal disorders by reduced heavy profiles of these stations. New cases of musculoskeletal disorders, surveyed by the company doctor among workers on the assembly lines had decreased since 1996. In 1999, the incidence increased again, despite the pursuit of ergonomic methods. This increase in musculoskeletal disorders was above all linked to a major reorganisation of work conditions, including a reduction in the cycle time on the assembly line, and to a move into a new workshop.     

固体火箭助推器CAD系统软件的研究与开发

针对固体火箭助推器的设计问题,本文将CAD技术运用于火箭研制过程,结合无人机助推发射系统设计与仿真软件,探讨当前固体火箭助推器CAD系统发展现状与特点,研究固体火箭助推器CAD系统的组成与实现方案,开发一套固体火箭助推器设计与仿真系统软件。系统集成助推器结构设计、参数化绘图、数据库管理3个模块。系统具有友好的操作界面,推进剂模块与装药设计模块之间进行了关联,可有效完成助推器产品管理,只需输入少量数据,便可快速构造助推器,为助推器方案论证提供了有力工具。     

Components of the visual computer: A review of relevant technologies

Visual computing emhpasizes visibility of information of interest and direct manipulation of visible information. It has become a dominant style of computing in recent years. In this paper, we review three major technologies that provide a platform for visual computing. These technologies reflect the needs of various people who use visual computers: programmers, end users, and scientists. We begin with a discussion of important developments in visual programming and follow with discussions of visual interfaces and visualization. We conclude with a summary of visual computing's current status and identify critical areas of research that should be emphasized in future work.