An object-oriented system for ergonomic risk assessment

Abstract: During the last decade, cumulative trauma disorders have become a major concern both to occupational health and safety professionals and manufacturing industries. This paper will present the development of a knowledge-based system for predicting the potential of developing strain injuries among employees exposed to repetitive and forceful activities. This potential is identified through the use of an expert system incorporating a fuzzy set algorithm. Recommendations for the prevention of the resulting CTDs are then provided by the system. The system executes on a microcomputer platform, and was constructed utilising a commercial object-oriented expert system shell.     

Lighting assessment of ergonomic workstation for radio diagnostic reporting

Within the diagnostic process, in the activities in which digital radiology systems are utilised, image display devices play a very important role. Such devices have to guarantee high performances in order to maintain the diagnostic quality of the displayed images and present them so that they can be observed optimally. In order to ensure the appropriate performance to the users, not only the image display device but also the whole workstation should be designed properly. Particular attention should be paid to the lighting conditions, to avoid compromising the radiologist's ability to observe the displayed images.The aim of this study is to assess the lighting of some workstations used for diagnostic radiology reporting, in order to obtain information about the visual interaction between worker and device and prevent health risks. A detailed analysis of the lighting of adjustable and nonadjustable workstations used for diagnostic radiology reporting was carried out in different rooms of the Radiology Department at the “Felice Lotti” Hospital in Pontedera (Pisa, Italy). The analysis was carried out thanks to in situ measurements (objective analysis) and the submission of an evaluation questionnaire to a sample composed by 16 radiologists (subjective analysis).From the obtained results it has been possible to point out that, in nonadjustable workstations the absence of a dedicated lighting system very often reveals the inadequacy of the general lighting in guaranteeing correct lighting conditions for the radiologists during the reading of the diagnostic monitors. As measure to reduce the visual fatigue of the radiologists, the use of a supplementary adjustable innovative LED backlight system was proposed. The use of the LED backlight system allows complying the requirements of the Technical Standards and mitigate the difference of luminance in the field of view of the radiologist. Due to that the use of the LED backlight system has been positively perceived by the examined sample, a significant part of whom has ascribed to this use a reduction in the visual fatigue.     

The rationalisation movement in perspective and some ergonomic implications

The paper gives an overview of the Rationalisation Movement from Taylor to the most recent organisation models such as 'Business Process Reengineering'. Special emphasis is put on the estimated implications of the different rationalisation strategies in terms of ergonomics/work physiology. In addition, basic terms and concepts are defined. According to the author, Taylorism, Fordism and Lean Production seem to offer an insufficient potential for good ergonomics. However, more recent organisational models such as 'Time Based Management' and 'Business Process Reengineering', may appear more promising but unfortunately almost no research has been conducted to describe the ergonomics implications of these models.     

Development of a software package for ergonomic assessment of manufacturing industry

A computer software package has been developed to be used as a self-assessment tool to evaluate ergonomic improvement potential of production systems by engineers, managers and safety professionals. Production managers of manufacturing industries with no prior knowledge of ergonomics were able to identify ergonomic deficiencies successfully (81%) in the shop floors as a result of the application of the ergonomic assessment tool. This enabled them to formulate intervention strategies to improve ergonomic conditions in their industries. The software package is user friendly, self-explanatory and provides relevant information, data and guidelines. It is unique, as the users will have access to necessary ergonomics information, which is often lacking in the manufacturing industries, especially in developing countries.     

An ergonomic expert system for risk assessment of work-related musculo-skeletal disorders

A computer-based expert system (SONEX) was developed to identify ergonomic risks for work-related musculoskeletal disorders (WRMSDs) in a wide variety of jobs and provide expert prevention advice. SONEX uses a rule base and 6 knowledge base modules: WRMSD risk factors are grouped into two main knowledge base modules (symptoms, engaged body part) with four supplementary knowledge base modules (work environment, work chair, work tools, organization factors). SONEX uses a menu-based interface and a series of simple questions that lead a user through each of the two main modules. Based on user responses it then recommends other knowledge base modules that are relevant for a detailed analysis of work risks. The SONEX rule base has over 140 questions, the knowledge base includes over 200 risk factors, and around 500 possible answers can be generated. SONEX relates ergonomic shortcomings in the job with worker's subjective symptoms; it predicts possible WRMSDs; and it offers preventive suggestions for ergonomic improvements to the job to prevent WRMSDs. It has been tested in a variety of work places with known ergonomic problems and with known employee WRMSDs by comparing its performance with conventional analytical methods and results show that it accurately predicts possible WRMSD risks and identifies ergonomic shortcomings. The advantages of SONEX are that it is much faster than other ergonomic analysis methods and it can be used by ergonomists and other professionals and also by workers themselves.     

Work organisation constructs and ergonomic outcomes among European forest machine operators

The aims of the study were to: 1) create work organisation constructs for forest machine operators; 2) examine relationships between these work organisation constructs and different ergonomic outcomes. The study was carried out among forest machine operators in six European countries and was based on a questionnaire survey (n = 358). Exploratory factor analysis (EFA) was used in the formation of the construct measures of work organisation. The EFA resulted in a five-factor structure. The factors were named ‘job control’, ‘variation’, ‘job rotation’, ‘breaks’ and ‘rate of work’. Three multiple regression analyses were carried out separately for the dependent variables job satisfaction, musculoskeletal symptoms and headache/sleeping problems. All regression analyses resulted in significant overall models. The highest explained variance among the dependent variables was found for job satisfaction (R = 0.51, i.e. ‘large’ effect size). The unique contribution of the work organisation constructs varied in the models, but ‘job rotation’ contributed significantly in all regression models. The results may be used as a source for ergonomic improvements to work organisation. The present study was performed as part of the EU project ‘ErgoWood’, which resulted in a European handbook for mechanised forest operations (Gellerstedt et al. 2005 Gellerstedt S. Lidén E. Bohlin F Health and performance in mechanised forest operations The Swedish University of Agricultural Sciences, Department of Forest Products and Markets Uppsala 2005  [Google Scholar]). The results delivered part of the evidence base for a toolbox in this handbook regarding changes in work organisation to improve health and performance.     

Work organisation constructs and ergonomic outcomes among European forest machine operators

The aims of the study were to: 1) create work organisation constructs for forest machine operators; 2) examine relationships between these work organisation constructs and different ergonomic outcomes. The study was carried out among forest machine operators in six European countries and was based on a questionnaire survey (n = 358). Exploratory factor analysis (EFA) was used in the formation of the construct measures of work organisation. The EFA resulted in a five-factor structure. The factors were named 'job control', 'variation', 'job rotation', 'breaks' and 'rate of work'. Three multiple regression analyses were carried out separately for the dependent variables job satisfaction, musculoskeletal symptoms and headache/sleeping problems. All regression analyses resulted in significant overall models. The highest explained variance among the dependent variables was found for job satisfaction (R = 0.51, i.e. 'large' effect size). The unique contribution of the work organisation constructs varied in the models, but 'job rotation' contributed significantly in all regression models. The results may be used as a source for ergonomic improvements to work organisation. The present study was performed as part of the EU project 'ErgoWood', which resulted in a European handbook for mechanised forest operations (Gellerstedt et al. 2005). The results delivered part of the evidence base for a toolbox in this handbook regarding changes in work organisation to improve health and performance.     

Inter-rater reliability of PATH observations for assessment of ergonomic risk factors in hospital work

This study examined the inter-rater reliability of expert observations of ergonomic risk factors by four analysts. Ten jobs were observed at a hospital using a newly expanded version of the PATH method (Buchholz et al. 1996), to which selected upper extremity exposures had been added. Two of the four raters simultaneously observed each worker onsite for a total of 443 observation pairs containing 18 categorical exposure items each. For most exposure items, kappa coefficients were 0.4 or higher. For some items, agreement was higher both for the jobs with less rapid hand activity and for the analysts with a higher level of ergonomic job analysis experience. These upper extremity exposures could be characterised reliably with real-time observation, given adequate experience and training of the observers. The revised version of PATH is applicable to the analysis of jobs where upper extremity musculoskeletal strain is of concern.     

A systematic review of comparative studies on ergonomic assessment techniques

This review provides a systematic overview of the comparison of ergonomic assessment techniques’ output in variety of industrial sectors.The relevant publications have been classified into broad categories such as comparison of applied industry sector, trend analysis, ergonomic assessment techniques been compared, comparative studies between two ergonomic assessment techniques, frequently compared techniques, levels of Action categories used. The summary of extracted data from included papers is provided.Authors have compared the results based on observational techniques which are easy to understand and apply. Available publications related to such comparison is limited. Authors have compared and analysed the correlation between the outputs of techniques but only few researchers pointed out the exact reason of variation in outputs applied in the same task. Hence, establishing applicability of each technique required. To identify the causes of variation, the sensitivity study of exposure factor-Task-posture assessment techniques is highly required. There are few techniques which are not yet compared for checking agreement or correlation, serving as a research gap.Authors have studied and published literature review specific to one technique of ergonomic assessment. Few authors have compared the outputs from various ergonomic assessment techniques in particular sector and investigated the correlation between them. No study has been carried out till date to review available literature on comparative study of comparisons made. In this paper, two research gaps have also been identified.     

The Etienne Grandjean Memorial Lecture Situated cognition and action: implications for ergonomic work analysis and anthropotechnology

Abstract

After a short history of the study of work activities, the methodology of Ergonomic Work Analysis (EWA) is described and the diversity of practices is underlined. The methodology of analysis of activities involves exhaustive checks of the behaviour of operators in critical situations and confronts the operator with his own behaviour in order to obtain pertinent explanations and evoke the cognitive unconscious. Ethnological work may constitute a contribution as regards the choice of the operator(s) whose behaviour is the most significant for the problem posed. In the same way, ethnologists using recording tools that are similar to those of ergonomists offer interesting frameworks for discussion of the qualities of these tools and the posture and balance aspects of behaviour. Moreover, interpersonal communications lead to beneficial exchanges with the ethnographic experience. Although the American school of situated cognition (cognitive and psychological anthropology) is very useful to know for activity analysts, it should not be confused with EWA which, by definition, is directed towards an objective: knowing and transforming obstacles of all types that hinder and prevent satisfactory activities. First of all, EWA has to show, from the viewpoint of operators, how they build problems in order to be able to solve them. Ergonomists and ethnologists note how difficult this problem building may be in view of the variability of the technical system and of the state of operators' knowledge. The technology transfer situations studied by anthropotechnology need EWA even more in view of the frequent degradation of technical systems and the heterogeneous character of the two cultures present in the mind of the operator: his own culture and that which has inspired the imported technology. From this viewpoint, here and there the operator may be considered not as a performer but as the iterative creator of his task.     

SEE: A proactive strategy-centric and deep learning-based ergonomic risk assessment system for risky posture recognition

Work-related musculoskeletal disorders (WMSDs) are serious workplace injuries that put workers' safety at risk. However, traditional WMSD assessments are based on the human-evaluation strategy (HES), requiring human intervention. Proactive strategy (PAS)-oriented WMSDs assessments collect data using posture data tags and special semi-human–machine equipment to improve efficiency and reduce human efforts to capture specific postures in a real-world setting. Meanwhile, more research on applying artificial intelligence-based pose machines for musculoskeletal risk assessment in various workplaces is needed. Hence, this study proposed a holistic posture acquisition and ergonomic risk analysis model with the PAS-oriented philosophy for developing a smartphone-based and workplace-based risk assessment system for WMSDs. The Convolutional Pose Machines (CPM) method was combined with a rapid entire body assessment method for the system's design. Finally, the smart ergonomic explorer (SEE) system includes three subsystems: an automotive scene capturer, an ergonomic risk level calculator, and a risk assessment reporter. A musculoskeletal risk assessment experiment with 13 poses was also carried out to validate the SEE system and compare its accuracy with manual evaluation. The result shows good agreement with the REBA score, with an average proportion agreement index (P0) of 0.962 and kappa of 0.82. It indicates that the proposed system can not only accurately analyze the working posture, but also accurately evaluate the total REBA scores. This study is hoped to provide practical advice and implications for achieving a more effective empirical response for WMSD assessment.     

Use of accelerometers as an ergonomic assessment method for arm acceleration-a large-scale field trial

Ergonomists need easy-to-use, quantitative job evaluation methods to assess risk factors for upper extremity work-related musculoskeletal disorders in field-based epidemiology studies. One device that may provide an objective measure of exposure to arm acceleration is a wrist-worn accelerometer or activity monitor. A field trial was conducted to evaluate the performance of a single-axis accelerometer using an industrial population (n=158) known to have diverse upper limb motion characteristics. The second phase of the field trial involved an examination of the relationship between more traditional observation-based ergonomic exposure measures and the monitor output among a group of assembly-line production employees (n=48) performing work tasks with highly stereotypic upper limb motion patterns. As expected, the linear acceleration data obtained from the activity monitor showed statistically significant differences between three occupational groups known observationally to have different upper limb motion requirements. Among the assembly-line production employees who performed different short-cycle assembly work tasks, statistically significant differences were also observed. Several observation-based ergonomic exposure measures were found to explain differences in the acceleration measure among the production employees who performed different jobs: hand and arm motion speed, use of the hand as a hammer, and, negatively, resisting forearm rotation from the torque of a power tool. The activity monitors were found to be easy to use and non-intrusive, and to be able to distinguish arm acceleration among groups with diverse upper limb motion characteristics as well as between different assembly job tasks where arm monitors were performed repeatedly at a fixed rate.     

Effects of semi-rigid arch-support orthotics: an investigation with potential ergonomic implications

For many years, arch-support orthotics have been prescribed for individuals with discomfort and/or abnormal skeletal alignments in the structures of the lower extremity. Recently there has been an increased interest in promoting semi-rigid orthotics as an ergonomic aid for asymptomatic workers who must stand all day at their workplace. A laboratory study was performed to assess the biomechanical impact of prefabricated semi-rigid orthotics on asymptomatic individuals. Ten subjects wore semi-rigid arch-support orthotics (experimental condition) for two months and flexible polyurethane/Sorbothane shoe inserts (control condition) for two months. Throughout this 18-week testing period, the subjects returned to the lab to perform a battery of assessment tests at regularly scheduled intervals. These tests examined subject strength, standing posture, stability, fatigue effects, and body part discomfort. The results of this study showed no significant changes in the strength, posture, or stability as a function of insert type. The subjects reported a reduction in low-back discomfort along with an increase in foot discomfort during a fatiguing exertion task while wearing the semi-rigid orthotics as compared to the control condition.     

Use of accelerometers as an ergonomic assessment method for arm acceleration a large-scale field trial

Ergonomists need easy-to-use, quantitative job evaluation methods to assess risk factors for upper extremity work-related musculoskeletal disorders in field-based epidemiology studies. One device that may provide an objective measure of exposure to arm acceleration is a wrist-worn accelerometer or activity monitor. A field trial was conducted to evaluate the performance of a single-axis accelerometer using an industrial population (n= 158) known to have diverse upper limb motion characteristics. The second phase of the field trial involved an examination of the relationship between more traditional observation-based ergonomic exposure measures and the monitor output among a group of assembly-line production employees (n= 48) performing work tasks with highly stereotypic upper limb motion patterns. As expected, the linear acceleration data obtained from the activity monitor showed statistically significant differences between three occupational groups known observationally to have different upper limb motion requirements. Among the assembly-line production employees who performed different short-cycle assembly work tasks, statistically significant differences were also observed. Several observation-based ergonomic exposure measures were found to explain differences in the acceleration measure among the production employees who performed different jobs: hand and arm motion speed, use of the hand as a hammer, and, negatively, resisting forearm rotation from the torque of a power tool. The activity monitors were found to be easy to use and non-intrusive, and to be able to distinguish arm acceleration among groups with diverse upper limb motion characteristics as well as between different assembly job tasks where arm monitors were performed repeatedly at a fixed rate.     

Development and evaluation of an office ergonomic risk checklist: ROSA--rapid office strain assessment

The Rapid Office Strain Assessment (ROSA) was designed to quickly quantify risks associated with computer work and to establish an action level for change based on reports of worker discomfort. Computer use risk factors were identified in previous research and standards on office design for the chair, monitor, telephone, keyboard and mouse. The risk factors were diagrammed and coded as increasing scores from 1 to 3. ROSA final scores ranged in magnitude from 1 to 10, with each successive score representing an increased presence of risk factors. Total body discomfort and ROSA final scores for 72 office workstations were significantly correlated (R = 0.384). ROSA final scores exhibited high inter- and intra-observer reliability (ICCs of 0.88 and 0.91, respectively). Mean discomfort increased with increasing ROSA scores, with a significant difference occurring between scores of 3 and 5 (out of 10). A ROSA final score of 5 might therefore be useful as an action level indicating when immediate change is necessary. ROSA proved to be an effective and reliable method for identifying computer use risk factors related to discomfort.     

基于Delphi排序改进的AHP-Fuzzy人机布局虚拟评价

基于Delphi专家排序,对传统AHP-Fuzzy算法从问卷数据处理和比较矩阵建立两个方向进行了改进,使该算法更适合Jack虚拟环境下的人机布局评价。侧重于工作空间中操纵器的人机布局虚拟评价。为解决目前人因工程分析工具几乎不考虑人在特定环境下的心理与生理感知的不足问题,将Jack人因分析工具分析出的客观数据与Delphi法相结合。在数据处理过程中,鉴于传统AHP-Fuzzy对评价指标两两对比时的整数赋值,不能很好地反映人类判断的模糊性,基于Delphi排序对AHP-Fuzzy进行了改进,可节约专家时间,并避免对判断矩阵进行一系列一致性检验与调整,减少部分计算量。使用飞机驾驶舱操纵器的人机布局虚拟评价进行了实例分析与验证。     

Comparison of ergonomic risk assessment outputs from OWAS and REBA in forestry timber harvesting

Globally, work-related (musculoskeletal disorders (MSDs) are one of the most important health problems encountered by ergonomists. Forest work, especially logging harvesting, is traditionally recognized as one of the most difficult types of physical work and has distinct characteristics. Harvesting works in forestry are composed of the following work stages: logging, skidding, and loading. This study aimed to examine risk factors of MSDs associated with different work postures during harvesting under variable external conditions by comparing work stages using the Ovako Working posture Assessment System (OWAS) and Rapid Entire Body Assessment (REBA). A statistically significant difference was observed between the two methods. While the difference in risk to the musculoskeletal system was statistically significant in different work stages using REBA, logging and skidding were assigned to the same risk level using OWAS. Easy-to-use ergonomic hand tools should be developed that are suitable for working conditions and help reduce MSD risk in forestry workers.     

An improved physical demand analysis framework based on ergonomic risk assessment tools for the manufacturing industry

Most of the operational tasks in the manufacturing process entail numerous physical involvements, despite the introduction of automated equipment. Due to this high physical demand in manufacturing, the need for proactive risk assessment to decrease potential injury cannot be ignored. Physical Demand Analysis (PDA) is a widely used tool recommended to all manufactures by the Canadian Workers’ Compensation Board to document the physical, cognitive, and environmental demands of essential tasks. However, limitations exist in utilizing the content generated in current PDA practice to conduct risk identification and risk assessment, and it has limited functionality for providing modified work to proactively mitigate risk. This paper summarizes the input requirements of risk assessment tools and proposes an improved PDA form with an integrated framework to facilitate the comprehensive and intelligent use of PDA. This paper focuses on three aspects of PDA implementation—risk identification, risk evaluation, and risk mitigation—targeting the development of modified work for the manufacturing industry. The framework is implemented in a window and door manufacturing facility, and a case study of a window glazing station is described in this paper in order to assess awkward body postures. Four main ergonomic risk assessments and identifications are recommended.     

In-field instrumented ergonomic risk assessment: Inertial measurement units versus Kinect V2

Musculoskeletal disorders are a major category of nonfatal work-related diseases in the industry. Therefore, various risk factor assessment methods, such as Rapid Upper Limb Assessment (RULA), were proposed for preventing musculoskeletal disorders in industrial environments. Nevertheless, RULA measurements based on workers' self-report or external rater observation are subjective and suffer from low repeatability. Thus, the objective of this paper is to investigate the accuracy and reliability of (1) a wearable technology (using inertial measurement units) and (2) a marker-less optical technology (using Kinect V2) for RULA risk assessment tool against motion-capture cameras (reference) for different manual material handling tasks. The obtained RULA scores were compared against the reference system using the proportion agreement index (Po) and Cohen's Kappa coefficient (κ). The wearable technology showed a “substantial” agreement (κ > 0.6) with the motion-capture cameras. The marker-less technology showed inconsistency in the agreement with the motion-capture cameras ranging from “fair” (κ < 0.4) to “moderate” (κ > 0.4) agreements, caused by both self-occlusion and object occlusion. Therefore, wearable technology showed to be more suitable than marker-less optical technology for in-field ergonomic risk assessment.