Comparison of self-report,video observation and direct measurement methods for upper extremity musculoskeletal disorder physical risk factors

The prevention of work-related musculoskeletal disorders has become a national priority in many countries. Increasingly, attempts are made to quantify those exposures that increase risk in order to set exposure limit values. This study used commonly employed field measurement methods and tools in order to perform an inter-method comparison between three primary methods of risk factor exposure assessment: self-report questionnaires, observational video analysis and direct measurement. Extreme posture duration, repetition, hand force (estimated from electromyography) and movement velocity were assessed for 18 subjects while performing each of three jobs processing tree seedlings. Results indicated that self-reports were the least precise assessment method, which consistently overestimated exposures for each of the measured risk factors. However, adjustment of the reports as psychophysical scales may increase agreement on a group level. Wrist flexion/extension duration and repetition were best measured by electrogoniometer. Electrogoniometric measures of wrist deviation duration and frequency were less precise than video analysis. Forearm rotation duration and repetition, grip force and velocity appeared to be best quantified by direct measurement as measured by electrogoniometer and electromyography (EMG) (as root-mean-square amplitude). The results highlight the fact that it is as important to consider and report estimated measurement error in order to reduce potential exposure misclassification in epidemiologic studies.     

面向康复工程的助行可穿戴外骨骼机器人的人类工效学设计

中国社会正在逐渐进入老龄化,肢体残疾人群数也在不断增加,这逐渐加剧了我国康复专业人才的供需矛盾。为了缓解该矛盾,针对下肢运动功能完全或部分丧失的偏瘫及截瘫患者,设计了PRMI助行外骨骼机器人。该外骨骼系统对其穿戴者提供运动补偿以帮助其自然和有效地独立行走。介绍了PRMI助行外骨骼机器人设计目的。通过对外骨骼的人类工效学设计的分析,对PRMI外骨骼的可调范围、关节的运动范围、最大力矩、运动学上的一致性以及人机交互进行了介绍。     

Forty years of IEA: some reflections on the evolution of ergonomics

This paper is the IEA Presidential Address to the 1997 IEA Triennial Congress in Tampere, Finland. The evolution of ergonomics prior to and after the foundation of the International Ergonomics Association in 1957 is reviewed. Ergonomics has broadened from considering work activities to include all types of human activities. The recent introduction of computers has changed many of the premises for work and leisure activities, and cognitive ergonomics is now as important as the ‘biological’ emphasis that was mentioned in the founding documents of IEA. Ergonomics is a science of design. There are three important targets for ergonomics design activity: to improve safety, productivity and operator satisfaction. A systems approach is presented to define how these parameters interact and how they can be measured.     

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.     

Evaluating functional clothing in climatic chamber tests versus field tests: a comparison of quantitative and qualitative methods in product development

For the evaluation of clothing by human beings, two different approaches can be identified- laboratory tests (i.e. climatic chamber tests) or field trials/wear trials. It has been suggested that the performance of clothing can be adequately predicted on the basis of the data obtained from climatic chamber tests and that field trials may be expendable altogether. From a product development perspective, this paper discusses the information provided by standard data collection methods and tools for the assessment of thermal comfort used in laboratory settings and compares this information with that acquired in field trials. When assessing the information provided in the laboratory test against those questions posed in a development process, the results highlight the insufficiency of objectively measurable criteria. Therefore, objective measurements alone cannot verify the adequacy of stated requirements for thermal comfort. The use of appropriate and sensitive tools for collecting subjective votes should also be noted, since small differences in thermal sensation affected the individual's preference for clothing. Exposed differences between subjects, in terms of thermophysiological as well as subjective responses, illustrate the importance of studying individual values and deviations as opposed to strict mean values for large populations in order to satisfy a potential user group. It is argued that complementary interviews form a basis for further understanding of ratings and preferences and that they should also be included in the climatic chamber evaluation 'tool box'. User satisfaction is based on a simultaneous assessment of partly opposing properties into a satisfying use value. Although laboratory test procedures can be developed and improved in relation to design issues, field evaluations must be regarded as an integrated part of an iterative development process. Only the actual use situation can provide the total spectrum of conditions on which basis requirements and/or properties can be prioritized or downgraded. This information forms the prerequisite for successful product development.     

汽车仪表板的人机工效多级模糊评价研究

针对汽车产品中潜在的大量由不合理的人机关系引起的安全隐患,选择了作为汽车中最重要的人机界面——仪表板,对它进行人机工效综合评价的探讨。利用模糊数学的理论,初步构建了汽车仪表板人机工效多级模糊评价的数学模型,并通过实例验证了可行性,为汽车仪表板的人机工效综合评价系统奠定了基础。     

Technology-aided participative methods in environmental assessment: An international perspective

Provisions for citizen involvement in the assessment of potential environmental effects of certain plans, programmes and projects are present in current legislation. An international survey revealed that public participation is common practice in European and some other countries worldwide. However, a number of issues are observed to affect public involvement in EIA/SEA processes and expert opinion differs when evaluating the effectiveness of existing participative methods.Results suggest that technology-aided methods can improve traditional participation processes. In particular, GIS has the potential to increase community knowledge and enhance involvement by communicating information more effectively. Variable accessibility to technology and data quality remain issues. Combining technology with more conventional ways of gathering, evaluating and presenting data are seen as offering a solution to the need to promote the integration of public perceptions in environmental assessment procedures. Recommendations to improve current public participation methods and measures for making GIS available to the general public are provided.     

The impact of organizational ergonomics on work effectiveness: with special reference to concurrent engineering in manufacturing industries

A theoretical interdisciplinary model that gives consideration to the critical human and organizational variables for success in concurrent engineering has been developed and validated based on the data derived from 103 electronic component manufacturing companies in the USA. The aim of the model is to determine the impact of organizational ergonomics on work effectiveness in concurrent engineering. A set of questionnaires was developed and data were collected from the manager of the concurrent engineering effort, the team leader and design, manufacturing and marketing team members. The study supports the proposed model and shows that a reward structure that reflects the team effort and quality of communication are significantly related to concurrent engineering performance. This implies that companies using team work structures should find ways to facilitate effective communication among team members and have a reward structure that is balanced to recognize the success of the team.     

Computer‐Aided Ergonomic Analysis for Assembly Unit of an Agricultural Device

In many applications, those who work on assembly processes are required to work in nonergonomic stances. Incorrect positions may cause strain and persistent problems. In addition, strain in workers’ bodies also has a negative effect on labor productivity. Ergonomics should be applied to avoid this kind of negative impact on workers’ health as well as productivity. Ergonomics introduces the basic principles of system productivity and human‐machine‐environment relationship. With a series of computer‐aided ergonomics analysis (CAEA), necessary precautions can be taken in advance by determining the undesirable stances. Through CAEA, productivity for machinery and comfort for people can be ensured by creating an efficient working environment without causing health problems for workers who work in production. In this study, in an agricultural equipment producing company, current working positions of a worker carrying out tasks during the assembly of wheel hay rakes, have been evaluated via the CATIA Ergonomic Analysis Module. On the basis of the results, the design of the assembly unit was ergonomically improved. As a result of the improvement in the working environment, unfavorable stance positions were avoided and production time was decreased by 60%.     

Stability of nonequidistant variable order multistep methods for stiff systems

The order, stability and convergence of the nonequidistant variable order multistep methods (NVOMMs) for stiff systems are discussed. The stability properties of certain class of variable step multistep methods (VSMMs) depending on one free parameter β^* for some order will be discussed, some theorems and lemmas are proved. New effective techniques restricted by larger interval of β^* to get strongly stable methods are determined     

A survey of tools and methods used by certified professional ergonomists

A survey of Certified Professional Ergonomists (CPEs) was conducted to gather information on the types of basic tools, direct and observational measurement techniques, and software used by practitioners. The motivation for the survey was to better understand what types of tools and methods practitioners use, their opinions of these tools, and to potentially gain an understanding of the constraints or preferences that influence this selection. Reasons for using or not using a selection of tools were also surveyed. Of 578 surveys that were delivered to CPEs and Associate Ergonomics Professionals, 308 were returned for a response rate of 53%. The respondents tended to be biased towards physical ergonomics, as the survey primarily focused on this area of ergonomics. A high percentage of respondents reported using tape measures, video cameras, stopwatches and digital cameras. The most commonly used observational methods were those involving manual materials handling, whereas the most commonly used direct measurement tools were pinch and grip dynamometers and push/pull gauges. The frequency and type of checklists, software, and anthropometric data used are summarized.     

Applying inductive learning to enhance knowledge-based expert systems

This paper describes the use of inductive learning in MARBLE, a knowledge-based expert system I have developed for assisting business loan evaluation. Inductive learning is the process of inferring classification concepts from raw data; I use this technique to generate loan-granting decision rules based on historical and proforma financial information. A learning method is presented in this paper that can induce decision rules from training examples.     

Survey on mechatronic engineering: A focus on design methods and product models

According to the principles of concurrent engineering and integrated design, engineers intend to develop a mechatronic system with a high level integration (functional and physical integrations) based on a well-organised design method. As a result, two main categories of issues have been pointed out: the process-based problems and the design data-related problems. Several approaches to overcome these issues have been put forward. To solve process-based problems, a dynamic perspective is generally used to present how collaboration can be improved during the mechatronic design. For design data-related problems, solutions generally come from product models and how to structure and store the data thanks to the functionality of data and documents management of Product Lifecycle Management systems. To be able to assess design methods and product models, some criteria are proposed in the paper and used to evaluate their added value on integrated design of mechatronic system. After this assessment, main outcomes which focus on the combination of design method and product model for improving the design of mechatronic system are finally discussed.     

Ergonomic contribution of ABLE exoskeleton in automotive industry

In PSA Peugeot Citroen factories, high precision requirements of workstations make them being manual. One of the main goal of the car manufacturer is to minimize the pain of workers while maintaining high efficiency of production lines. Consequently, assisting operators with an exoskeleton is a potential solution for improving ergonomics of painful workstations while respecting industrial constraints. To determine ergonomic performances of an exoskeleton, human joint angles and torques, ground reaction forces, and duration of operations are analysed for eight subjects performing a representative screwing task. Experiments were performed using ABLE upper-limb exoskeleton, developed by the French Atomic Energy Commission (CEA), which has the functionality to compensate arm and tools loads. Results show a clear reduction of the sum of the joints torques, up to 38.9%, given by ABLE supply and invite to make concrete the use of exoskeletons in car assembly lines.     

Ergonomic evaluation of masons laying concrete masonry units and autoclaved aerated concrete

Masons working with concrete masonry unit block have high rates of work-related musculoskeletal disorders to the low back and shoulders associated with repetitively lifting and buttering heavy block. A new material, autoclaved aerated concrete, may reduce the risk of shoulder and back injury but, ergonomic evaluation is needed. This study evaluated shoulder exposure parameters, low back stress, and worker perceptions in two groups of journey level masons, one using CMU and the other using AAC block. Results indicate that for the left arm AAC masons spent significantly more time than CMU masons in static (38.2% versus 31.1%, respectively), and less time in slow motions (48.2% versus 52.2%, respectively) and faster motions (13.6% versus 16.7%, respectively) (p < 0.05). CMU masons had significantly greater shoulder and low back pain (p = 0.009) and they held block significantly longer than AAC masons (p < 0.001). Low back compressive forces were high for both materials. Masons handling AAC demonstrated less left upper extremity stress but both materials were estimated to be hazardous to the low back.     

Ergonomic evaluation and comparison of wood harvesting systems in Northwest Russia

A comparison of 14 currently applicable wood harvesting systems was assessed with respect to ergonomic point of view. For this purpose, the research method, based on the Hodges–Lehmann rule and the integrated work-severity rate of single machinery, was developed for ergonomic evaluation of cut-to-length, tree-length and full-tree harvesting systems. Altogether, about 130 different parameters of 36 units of equipment that impact on the ergonomics and work conditions were measured and estimated in interviews undertaken directly at forestry harvesting workplaces in 15 logging companies in the Republic of Karelia, Northwest Russia. Then the results were compared to the effective norms, and the degree of compliance with the stipulated values was determined. The estimates obtained for the degree of compliance were combined. This permits a direct comparison of the workload on forestry harvesting workers such as operators, lumberjacks and choker setters. In many respects, the current ergonomic standard is standard, except for the operators of cable skidders, chainsaws and choker settings. Visibility and work postures were considered to be the most critical features influencing the operator's performance. Problems still exist, despite the extensive development of cabs. The best working conditions in terms of harvesting systems were provided by “harvester + forwarder” in cut-to-length harvesting, and “feller–buncher + grapple skidder” in full-tree harvesting. The motor-manual tree-length harvesting performed with cable skidders showed the worst results in terms of ergonomics.     

Ergonomic assessment and workstation design of shipping crane cabin in steel industry

Ergonomics plays vital role to improve health and productivity at workplace and in last two decades it find importance to redesign workplace. All Indian industries had taken initiative to redesign their workplace to overcome various musculoskeletal disorders (MSD) and work related injuries. In this context, the project has been carried out in an integrated steel plant located in central India where most of the crane operator was continuously suffering from muscular pain in different body parts. Risk of MSD was identified by detailed questionnaire from 27 crane operator. It was revealed that almost all crane operators were continuously suffering from some kind of MSD. Based on the anthropometric data of 50 percentile Indian male, ergonomic assessment, redesign and evaluation of crane cabin was carried out in CATIA-V5 software. To check the compatibility of the design, rapid upper limb assessment (RULA) for both existing as well as modified crane cabin was performed. This study shows that intervention of ergonomics in workplace reduces the mismatch between man and machine and makes workplace comfortable for work.     

A new class of intelligent knowledge-based systems with an optimisation-based inference engine

In this paper we describe a new class of intelligent knowledge-based system (IKBS) which can be used principally for managerial decision making applications. This class of applications often requires a framework for knowledge acquisition which allows the system to use the knowledge of several experts. In addition, since in most business decision making the objective is maximise profits, there is a need for an inference engine which allows optimisation to be carried out. The new class of IKBS which is described in this paper has both these properties, i.e., the ability to use the knowledge of multiple experts in a convenient way and an inference engine which by performing optimisations is able to pick out the profit maximising decisions. As an illustration of these concepts, a system for allocation decision making is described. The system ‘Retail-opt’ allows the user to solve problems like allocation of space in retail outlets, allocation of space in mail order catalogues, pricing policy decisions for discounted airline tickets, etc. In the paper, the basic concepts behind ‘Retail-opt’ are described and an application of ‘Retail-opt’ to the problem of retail space allocation in a Scandinavian Department Store is given. A number of other systems which use these concepts for more complicated competitive decision making situations are also described.     

Enhancing the impact of ergonomics interventions

The aim of this paper was to provide recommendations for ergonomists involved in project design and evaluation. Twelve research and consultancy projects involving ergonomics interventions in a variety of settings in The Netherlands were analysed to identify factors important to success. Projects included participatory and non-participatory cases. Eight factors were identified for successful project design and for demonstrating project effectiveness.