Pub Date : 2014-05-13DOI: 10.1080/21577323.2014.920437
A. Kluge, Salman Nazir, D. Manca
OCCUPATIONAL APPLICATIONS Operators play a vital role in production and safety in industrial processes. Since the introduction of advanced control techniques, such as model predictive control and real-time optimization, operators’ acquisition of adequate mental models to develop complex cause-and-effect relationship explaining plant behavior has been increasingly challenged. Additionally, distinct challenges have arisen with respect to crew coordination between control room and field operators to orchestrate a coordinated flow of actions to assess situations or choose a course of action. Based on an analysis of training needs, it is argued that traditional training practice, such as the use of operator training simulators, could be advanced by using current training environments, such as virtual reality training simulators. This would allow using modern training technology and its advancements in parallel to the advancements of control techniques to support production and safety at its best. TECHNICAL ABSTRACT Background: Extensive integration of various modern methods in the process industry has changed the tasks of industrial operators. The integration of advanced technology and control algorithms lead to new challenges faced by control room and field operators, from both technical and crew-coordination complexity perspectives. From a technical perspective, couplings, dynamic effects, non-transparency, conflicting goals, comprehension of model predictive control, and real-time optimization challenge the development of an accurate mental model. From a crew-coordination complexity perspective, control room operators and field operators face the challenge to orchestrate their individual actions into a coordination flow of actions to assess a situation and solve problems. Purpose: The purpose of this article is to highlight the cognitive and teamwork requirements of operators and to note the limitations of current training practices compared to the training objectives that need to be achieved individually and as a team. Methods: Evidence is presented from instance-based learning theory and theories addressing the acquisition of mental models, instances, and skills for crew-coordination complexity; this is used to suggest that current training practices match only a subset of the challenging training objectives that are essential to use technology efficiently and safely. Results: Findings from the cognitive training need analysis are linked to training objectives and training methods based on the learning theories presented. Additionally, arguments for using different training environments (operator training simulators, virtual reality training simulators) to achieve the training objectives in an optimal way are presented. Conclusions: It is concluded that advancements in the applications of process control techniques call for a new mindset in the training of operators. Advanced training methods and environments can be one way of helping the operato
{"title":"Advanced Applications in Process Control and Training Needs of Field and Control Room Operators","authors":"A. Kluge, Salman Nazir, D. Manca","doi":"10.1080/21577323.2014.920437","DOIUrl":"https://doi.org/10.1080/21577323.2014.920437","url":null,"abstract":"OCCUPATIONAL APPLICATIONS Operators play a vital role in production and safety in industrial processes. Since the introduction of advanced control techniques, such as model predictive control and real-time optimization, operators’ acquisition of adequate mental models to develop complex cause-and-effect relationship explaining plant behavior has been increasingly challenged. Additionally, distinct challenges have arisen with respect to crew coordination between control room and field operators to orchestrate a coordinated flow of actions to assess situations or choose a course of action. Based on an analysis of training needs, it is argued that traditional training practice, such as the use of operator training simulators, could be advanced by using current training environments, such as virtual reality training simulators. This would allow using modern training technology and its advancements in parallel to the advancements of control techniques to support production and safety at its best. TECHNICAL ABSTRACT Background: Extensive integration of various modern methods in the process industry has changed the tasks of industrial operators. The integration of advanced technology and control algorithms lead to new challenges faced by control room and field operators, from both technical and crew-coordination complexity perspectives. From a technical perspective, couplings, dynamic effects, non-transparency, conflicting goals, comprehension of model predictive control, and real-time optimization challenge the development of an accurate mental model. From a crew-coordination complexity perspective, control room operators and field operators face the challenge to orchestrate their individual actions into a coordination flow of actions to assess a situation and solve problems. Purpose: The purpose of this article is to highlight the cognitive and teamwork requirements of operators and to note the limitations of current training practices compared to the training objectives that need to be achieved individually and as a team. Methods: Evidence is presented from instance-based learning theory and theories addressing the acquisition of mental models, instances, and skills for crew-coordination complexity; this is used to suggest that current training practices match only a subset of the challenging training objectives that are essential to use technology efficiently and safely. Results: Findings from the cognitive training need analysis are linked to training objectives and training methods based on the learning theories presented. Additionally, arguments for using different training environments (operator training simulators, virtual reality training simulators) to achieve the training objectives in an optimal way are presented. Conclusions: It is concluded that advancements in the applications of process control techniques call for a new mindset in the training of operators. Advanced training methods and environments can be one way of helping the operato","PeriodicalId":73331,"journal":{"name":"IIE transactions on occupational ergonomics and human factors","volume":"2 1","pages":"121 - 136"},"PeriodicalIF":0.0,"publicationDate":"2014-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21577323.2014.920437","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60124325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-04-08DOI: 10.1080/21577323.2014.911222
Leanna M Reardon, John R Heberger, Patrick G Dempsey
Background: Maintenance and repair work in mining is particularly hazardous and yet has received little focus in ergonomics research.
Purpose: In this article, an attempt has been made to determine if patterns can be identified to categorize maintenance and repair fatalities in mining, to compare occurrence of fatalities between coal and metal/nonmetal sectors, and to use this information to identify safety deficiencies and associated proposed remedial measures.
Methods: A classification scheme was developed to identify patterns in fatalities, including proximal causes, tasks, and contributing factors. This scheme was tested to ensure adequacy of the categories, and fatalities were categorized using the scheme. All testing and categorization were done by two of the authors to ensure reliability of the coding scheme.
Results: Patterns were successfully identified to categorize the fatalities, and these patterns were different between coal and metal/nonmetal mines. Coal mines had a greater proportion of electrical-related fatalities, while more fatalities related to potential energy occurred at metal/nonmetal mines. Most of the fatalities were caused by the victim coming into contact with an object or machine or the victim falling from height, and they occurred most often while the victim was performing maintenance or repair on equipment, cleaning, or removing blockages. The most frequent factors contributing to these incidents were failure to properly de-energize or lock out/tag out equipment, violation of work procedures, missing or inadequate safety equipment, and failure to block equipment properly.
Conclusions: The classification approach used was successful in identifying hazard patterns during maintenance and repair fatalities in mining. These patterns identify areas to focus attention when developing interventions to prevent the occurrence of future fatalities.
{"title":"Analysis of Fatalities During Maintenance and Repair Operations in the U.S. Mining Sector.","authors":"Leanna M Reardon, John R Heberger, Patrick G Dempsey","doi":"10.1080/21577323.2014.911222","DOIUrl":"10.1080/21577323.2014.911222","url":null,"abstract":"<p><strong>Background: </strong>Maintenance and repair work in mining is particularly hazardous and yet has received little focus in ergonomics research.</p><p><strong>Purpose: </strong>In this article, an attempt has been made to determine if patterns can be identified to categorize maintenance and repair fatalities in mining, to compare occurrence of fatalities between coal and metal/nonmetal sectors, and to use this information to identify safety deficiencies and associated proposed remedial measures.</p><p><strong>Methods: </strong>A classification scheme was developed to identify patterns in fatalities, including proximal causes, tasks, and contributing factors. This scheme was tested to ensure adequacy of the categories, and fatalities were categorized using the scheme. All testing and categorization were done by two of the authors to ensure reliability of the coding scheme.</p><p><strong>Results: </strong>Patterns were successfully identified to categorize the fatalities, and these patterns were different between coal and metal/nonmetal mines. Coal mines had a greater proportion of electrical-related fatalities, while more fatalities related to potential energy occurred at metal/nonmetal mines. Most of the fatalities were caused by the victim coming into contact with an object or machine or the victim falling from height, and they occurred most often while the victim was performing maintenance or repair on equipment, cleaning, or removing blockages. The most frequent factors contributing to these incidents were failure to properly de-energize or lock out/tag out equipment, violation of work procedures, missing or inadequate safety equipment, and failure to block equipment properly.</p><p><strong>Conclusions: </strong>The classification approach used was successful in identifying hazard patterns during maintenance and repair fatalities in mining. These patterns identify areas to focus attention when developing interventions to prevent the occurrence of future fatalities.</p>","PeriodicalId":73331,"journal":{"name":"IIE transactions on occupational ergonomics and human factors","volume":"2 1","pages":"27-38"},"PeriodicalIF":0.0,"publicationDate":"2014-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102269/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60123818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-04-04DOI: 10.1080/21577323.2014.905885
Maia B. Cook, H. Smallman, C. Rieth
OCCUPATIONAL APPLICATIONS Legacy status display formats limit the number of processes that human operators can effectively and proactively monitor. Through a design approach targeting the needs of human attention, a novel trend–icon hybrid status display format (Trendicon; patent pending; Fisher Rosemount Systems, Inc., Round Rock, TX) was developed for proactive monitoring. An experiment contrasting Trendicons with digital values and trend graphs revealed that after minimal training, Trendicons supported earlier problem detections and more frequent proactive detections. Further, Trendicons led to a roughly fivefold increase in process indicators that participants could effectively oversee. Practical implications include earlier problem detection, improved system operation, and an increased operator span of control. Participants’ incorrect initial intuitions about display effectiveness highlight potential pitfalls of flexible, configurable displays. Trendicons are being developed for process and military control displays. The attention management design approach taken here is applicable to the design of supervisory status views for display-mediated work domains. TECHNICAL ABSTRACT Background: Process control operators rely heavily on their visual displays to monitor and stay abreast of processes and situations, anticipate future status, and proactively detect and resolve emerging problems. However, fielded status displays support only a subset of these tasks and can engender reactive rather than proactive monitoring because of inadequate attention management. Reactive monitoring is a significant barrier to effective operations and increasing operator span of control. Purpose: The benefits of an attention management design approach are demonstrated through the development and evaluation of a novel trend–icon hybrid (Trendicon) display format to support proactive monitoring. Methods: A within-subjects experiment contrasted the effectiveness of three status indicator formats—digital values, trend graphs, and Trendicons—in supporting proactive detection of emerging deviations. Span of control was assessed by varying the number of concurrently monitored status indicators (4, 12, and 24). Participants’ intuitions and preferences for the indicator formats were assessed as a proxy for display configuration choices. Results: Monitoring was largely reactive for digital values and trend graphs. In contrast, Trendicons promoted earlier problem detections and more frequent proactive detections, leading to a nearly fivefold increase in effective span of control. However, participants initially underestimated the utility of Trendicons. Conclusions: By explicitly designing attention management into new representations of process status, a dramatic increase in effective span of control was achieved over legacy formats. Better allocation of limited attentional resources during monitoring helped shift the nature of monitoring from reactive to proactive. Miscalibrat
传统状态显示格式限制了人工操作员能够有效和主动监控的流程数量。通过针对人类关注需求的设计方法，一种新颖的趋势-图标混合状态显示格式(Trendicon;专利申请中;Fisher Rosemount Systems, Inc.， Round Rock, TX)是为主动监测而开发的。将Trendicons与数字值和趋势图进行对比的实验表明，经过最少的训练，Trendicons支持更早的问题检测和更频繁的主动检测。此外，Trendicons导致参与者可以有效监督的过程指标增加了大约五倍。实际意义包括更早地发现问题，改进系统操作，以及增加操作员的控制范围。参与者最初对显示效果的错误直觉凸显了灵活、可配置显示的潜在缺陷。过程和军事控制显示的趋势正在发展。本文采用的注意力管理设计方法适用于显示介导工作域的监督状态视图设计。技术摘要背景:过程控制操作员在很大程度上依赖于他们的视觉显示器来监控和了解过程和情况，预测未来的状态，并主动发现和解决新出现的问题。然而，现场状态显示只支持这些任务的一个子集，并且由于注意力管理不足，可能导致被动而不是主动监控。被动监测是影响有效作业和提高作业人员控制范围的重要障碍。目的:通过开发和评估一种新的趋势-图标混合(Trendicon)显示格式来支持主动监测，展示了注意力管理设计方法的好处。方法:一项受试者内部实验对比了三种状态指示格式——数字值、趋势图和趋势图——在支持主动检测新出现的偏差方面的有效性。通过改变同时监测的状态指示器(4、12和24)的数量来评估控制范围。参与者对指示格式的直觉和偏好被评估为显示配置选择的代理。结果:对数字值和趋势图的监测主要是被动的。相比之下，Trendicons促进了更早的问题检测和更频繁的主动检测，导致有效控制范围增加了近五倍。然而，参与者最初低估了Trendicons的效用。结论:通过明确地将注意力管理设计成过程状态的新表示，与遗留格式相比，有效控制范围显著增加。在监测期间更好地分配有限的注意力资源有助于将监测的性质从被动转变为主动。错误的性能直觉和偏好表明，设计师必须同时考虑性能和用户对显示效果的看法。Trendicons在过程控制和军事控制显示方面的应用正在不断发展。设计和解决显示介导的监督控制的潜在认知挑战可以导致更有效的系统操作，更安全的异常情况管理，并提高生产力。
{"title":"Increasing the Effective Span of Control: Advanced Graphics for Proactive, Trend-Based Monitoring","authors":"Maia B. Cook, H. Smallman, C. Rieth","doi":"10.1080/21577323.2014.905885","DOIUrl":"https://doi.org/10.1080/21577323.2014.905885","url":null,"abstract":"OCCUPATIONAL APPLICATIONS Legacy status display formats limit the number of processes that human operators can effectively and proactively monitor. Through a design approach targeting the needs of human attention, a novel trend–icon hybrid status display format (Trendicon; patent pending; Fisher Rosemount Systems, Inc., Round Rock, TX) was developed for proactive monitoring. An experiment contrasting Trendicons with digital values and trend graphs revealed that after minimal training, Trendicons supported earlier problem detections and more frequent proactive detections. Further, Trendicons led to a roughly fivefold increase in process indicators that participants could effectively oversee. Practical implications include earlier problem detection, improved system operation, and an increased operator span of control. Participants’ incorrect initial intuitions about display effectiveness highlight potential pitfalls of flexible, configurable displays. Trendicons are being developed for process and military control displays. The attention management design approach taken here is applicable to the design of supervisory status views for display-mediated work domains. TECHNICAL ABSTRACT Background: Process control operators rely heavily on their visual displays to monitor and stay abreast of processes and situations, anticipate future status, and proactively detect and resolve emerging problems. However, fielded status displays support only a subset of these tasks and can engender reactive rather than proactive monitoring because of inadequate attention management. Reactive monitoring is a significant barrier to effective operations and increasing operator span of control. Purpose: The benefits of an attention management design approach are demonstrated through the development and evaluation of a novel trend–icon hybrid (Trendicon) display format to support proactive monitoring. Methods: A within-subjects experiment contrasted the effectiveness of three status indicator formats—digital values, trend graphs, and Trendicons—in supporting proactive detection of emerging deviations. Span of control was assessed by varying the number of concurrently monitored status indicators (4, 12, and 24). Participants’ intuitions and preferences for the indicator formats were assessed as a proxy for display configuration choices. Results: Monitoring was largely reactive for digital values and trend graphs. In contrast, Trendicons promoted earlier problem detections and more frequent proactive detections, leading to a nearly fivefold increase in effective span of control. However, participants initially underestimated the utility of Trendicons. Conclusions: By explicitly designing attention management into new representations of process status, a dramatic increase in effective span of control was achieved over legacy formats. Better allocation of limited attentional resources during monitoring helped shift the nature of monitoring from reactive to proactive. Miscalibrat","PeriodicalId":73331,"journal":{"name":"IIE transactions on occupational ergonomics and human factors","volume":"2 1","pages":"137 - 151"},"PeriodicalIF":0.0,"publicationDate":"2014-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21577323.2014.905885","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60123700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-04-03DOI: 10.1080/21577323.2014.962712
Daniel Viggiani, Mamiko Noguchi, Kristina M. Gruevski, D. De Carvalho, J. Callaghan
OCCUPATIONAL APPLICATIONS Occupational sitting has been associated with an increased risk for developing low back pain. The present investigation examined the effects of asymmetrical sitting surfaces induced by a wallet on acute changes in spine/pelvis posture, interface pressure, and discomfort. Compared to level sitting, sitting on a wallet resulted in greater sagittal and lateral spine flexion, a smaller total contact area with the seat pan, and greater gluteal discomfort. At wallet thicknesses of 22 mm and thicker, seat pan contact pressure area decreased and thoracic spine and pelvic angles deviated laterally compared to the no-wallet condition. At a 32-mm wallet thickness, gluteal discomfort increased. These results indicate that sitting for brief periods (15 minutes) on an uneven seating surface greater than 32 mm in thickness causes postural deviations from neutral spine positions and increases gluteal discomfort. This study supports the removal of rear pocket items, especially larger ones, during sitting. TECHNICAL ABSTRACT Background: Occupations in mobile or office settings can involve prolonged seated exposures, increasing the likelihood of low back pain development. The seat-occupant interface can be impeded by wallets or other objects (cell phones, paper documents, etc.) placed in the rear pocket, potentially increasing the risk of developing low back pain directly (nerve compression) or indirectly (altered kinematics). However, there are no published studies that have examined the effect of an uneven seating surface. Purpose: This study aimed to quantify the outcomes of a non-level sitting surface on trunk kinematics, seat pan pressure distribution, and discomfort. Gender differences in responses were also examined. Methods: Twelve males and 12 females sat for 15 minutes each on 4 wallet thicknesses (0, 12, 22, and 32 mm). Sagittal and frontal plane angles of the thoracic, lumbar spine and the pelvis were measured. Seat pressure distribution (total pressure area) and discomfort using a 100-mm visual analogue scale were also collected for each thickness. Results: In the 22- and 32-mm conditions, there was greater pelvic posterior rotation, pelvic left lateral bending, thoracic flexion, and thoracic right lateral bending compared to the 0-mm condition. Males and females showed differences in the magnitude of lateral bend angles at all spine levels; however, both genders demonstrated the same directions of postural compensation. Total pressure area decreased and gluteal discomfort increased with thicker wallets, reaching significance in the 22- and 32-mm conditions, respectively. Conclusions: Sitting on wallets greater than 32 mm in thickness increased gluteal discomfort reporting after short duration exposures. Asymmetrical sitting promotes non-neutral spine postures and reduces seat pan contact area. Asymmetrical sitting is therefore not recommended, even for short duration exposures.
{"title":"The Effect of Wallet Thickness on Spine Posture, Seat Interface Pressure, and Perceived Discomfort During Sitting","authors":"Daniel Viggiani, Mamiko Noguchi, Kristina M. Gruevski, D. De Carvalho, J. Callaghan","doi":"10.1080/21577323.2014.962712","DOIUrl":"https://doi.org/10.1080/21577323.2014.962712","url":null,"abstract":"OCCUPATIONAL APPLICATIONS Occupational sitting has been associated with an increased risk for developing low back pain. The present investigation examined the effects of asymmetrical sitting surfaces induced by a wallet on acute changes in spine/pelvis posture, interface pressure, and discomfort. Compared to level sitting, sitting on a wallet resulted in greater sagittal and lateral spine flexion, a smaller total contact area with the seat pan, and greater gluteal discomfort. At wallet thicknesses of 22 mm and thicker, seat pan contact pressure area decreased and thoracic spine and pelvic angles deviated laterally compared to the no-wallet condition. At a 32-mm wallet thickness, gluteal discomfort increased. These results indicate that sitting for brief periods (15 minutes) on an uneven seating surface greater than 32 mm in thickness causes postural deviations from neutral spine positions and increases gluteal discomfort. This study supports the removal of rear pocket items, especially larger ones, during sitting. TECHNICAL ABSTRACT Background: Occupations in mobile or office settings can involve prolonged seated exposures, increasing the likelihood of low back pain development. The seat-occupant interface can be impeded by wallets or other objects (cell phones, paper documents, etc.) placed in the rear pocket, potentially increasing the risk of developing low back pain directly (nerve compression) or indirectly (altered kinematics). However, there are no published studies that have examined the effect of an uneven seating surface. Purpose: This study aimed to quantify the outcomes of a non-level sitting surface on trunk kinematics, seat pan pressure distribution, and discomfort. Gender differences in responses were also examined. Methods: Twelve males and 12 females sat for 15 minutes each on 4 wallet thicknesses (0, 12, 22, and 32 mm). Sagittal and frontal plane angles of the thoracic, lumbar spine and the pelvis were measured. Seat pressure distribution (total pressure area) and discomfort using a 100-mm visual analogue scale were also collected for each thickness. Results: In the 22- and 32-mm conditions, there was greater pelvic posterior rotation, pelvic left lateral bending, thoracic flexion, and thoracic right lateral bending compared to the 0-mm condition. Males and females showed differences in the magnitude of lateral bend angles at all spine levels; however, both genders demonstrated the same directions of postural compensation. Total pressure area decreased and gluteal discomfort increased with thicker wallets, reaching significance in the 22- and 32-mm conditions, respectively. Conclusions: Sitting on wallets greater than 32 mm in thickness increased gluteal discomfort reporting after short duration exposures. Asymmetrical sitting promotes non-neutral spine postures and reduces seat pan contact area. Asymmetrical sitting is therefore not recommended, even for short duration exposures.","PeriodicalId":73331,"journal":{"name":"IIE transactions on occupational ergonomics and human factors","volume":"2 1","pages":"83 - 93"},"PeriodicalIF":0.0,"publicationDate":"2014-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21577323.2014.962712","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60124283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-04-03DOI: 10.1080/21577323.2014.948694
S. Fischer, Ron Johnson, M. Abdoli-Eramaki, K. Woodcock
OCCUPATIONAL APPLICATIONS Upper extremity injuries pose a considerable problem to sign language interpreters. Over 1 hour of interpretation, interpreters experienced a decrease in their mean rate of wrist flexion and extension, while novices also experienced decreases about other wrist and elbow axes as well. It is suspected that interpreters were beginning to fatigue over the 1-hour duration, more so among novices, and that this increasing fatigue may be reducing their ability to “keep-up” with the interpretation. While more research is needed to measure fatigue and the quality of sign output, 1 hour of signing can induce changes in a signer's movements. In the near term, injury-prevention efforts could focus on helping interpreters (particularly novices) structure their workload to ensure they provide themselves with ample opportunities for recovery. Imposing stricter guidelines regarding the maximum length of a continuous interpretation session is one example of a practical, near-term intervention. TECHNICAL ABSTRACT Background: Sign language interpreters frequently report pain, and many develop musculoskeletal disorders. Yet, there is limited research quantifying the mechanics of signing independently or how such factors as experience or duration might influence those mechanics. Purpose: The purpose of this study is to determine if duration (within a single session) or experience affected kinematics during a 1-hour simulated classroom interpreting session. Methods: Nine novice (<2 years of experience) and nine experienced (≥5 years of experience) sign language interpreters interpreted for a continuous 60-minute session. Kinematic measures of the left and right upper extremities were recorded and compared between groups (experience) and within participants (time). Results: Duration had a significant effect on the mean angular velocity of right wrist and elbow movements. Novices exhibited decreased velocities between the first and last 15-minute samples for all right limb velocity measures (interaction effect). However, experienced interpreters only exhibited this decrease at the right wrist about the flexion/extension axis (main effect). Additionally, the number of micro-breaks increased between the first and last 15-minute samples about the wrist flexion/extension axis in both groups (main effect) and about the right elbow flexion/extension axis only among novices (interaction effect). Conclusions: Despite anecdotal evidence suggesting that novice interpreters use a less effective signing approach, these data suggest that on the basis of kinematics, novice and experienced sign language interpreters sign using similar kinematics, at least during the initial 15 minutes of an interpreting session. However, over the course of a continuous 1-hour session, differences emerge. It is plausible that novices may be more fatigable than their experienced counterparts or that they have not yet learned strategies to slow the accumulation of fatigue while m
{"title":"Investigating the Effect of Experience and Duration on Kinematics During 1 Hour of Sign Language Interpreting","authors":"S. Fischer, Ron Johnson, M. Abdoli-Eramaki, K. Woodcock","doi":"10.1080/21577323.2014.948694","DOIUrl":"https://doi.org/10.1080/21577323.2014.948694","url":null,"abstract":"OCCUPATIONAL APPLICATIONS Upper extremity injuries pose a considerable problem to sign language interpreters. Over 1 hour of interpretation, interpreters experienced a decrease in their mean rate of wrist flexion and extension, while novices also experienced decreases about other wrist and elbow axes as well. It is suspected that interpreters were beginning to fatigue over the 1-hour duration, more so among novices, and that this increasing fatigue may be reducing their ability to “keep-up” with the interpretation. While more research is needed to measure fatigue and the quality of sign output, 1 hour of signing can induce changes in a signer's movements. In the near term, injury-prevention efforts could focus on helping interpreters (particularly novices) structure their workload to ensure they provide themselves with ample opportunities for recovery. Imposing stricter guidelines regarding the maximum length of a continuous interpretation session is one example of a practical, near-term intervention. TECHNICAL ABSTRACT Background: Sign language interpreters frequently report pain, and many develop musculoskeletal disorders. Yet, there is limited research quantifying the mechanics of signing independently or how such factors as experience or duration might influence those mechanics. Purpose: The purpose of this study is to determine if duration (within a single session) or experience affected kinematics during a 1-hour simulated classroom interpreting session. Methods: Nine novice (<2 years of experience) and nine experienced (≥5 years of experience) sign language interpreters interpreted for a continuous 60-minute session. Kinematic measures of the left and right upper extremities were recorded and compared between groups (experience) and within participants (time). Results: Duration had a significant effect on the mean angular velocity of right wrist and elbow movements. Novices exhibited decreased velocities between the first and last 15-minute samples for all right limb velocity measures (interaction effect). However, experienced interpreters only exhibited this decrease at the right wrist about the flexion/extension axis (main effect). Additionally, the number of micro-breaks increased between the first and last 15-minute samples about the wrist flexion/extension axis in both groups (main effect) and about the right elbow flexion/extension axis only among novices (interaction effect). Conclusions: Despite anecdotal evidence suggesting that novice interpreters use a less effective signing approach, these data suggest that on the basis of kinematics, novice and experienced sign language interpreters sign using similar kinematics, at least during the initial 15 minutes of an interpreting session. However, over the course of a continuous 1-hour session, differences emerge. It is plausible that novices may be more fatigable than their experienced counterparts or that they have not yet learned strategies to slow the accumulation of fatigue while m","PeriodicalId":73331,"journal":{"name":"IIE transactions on occupational ergonomics and human factors","volume":"2 1","pages":"60 - 70"},"PeriodicalIF":0.0,"publicationDate":"2014-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21577323.2014.948694","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60123949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-04-03DOI: 10.1080/21577323.2014.956944
N. Toosizadeh, M. Nussbaum
OCCUPATIONAL APPLICATIONS Results from the current study show evidence of an adverse effect of prolonged trunk flexion on spine loads during consecutive lifting tasks. The time-dependent methodology introduced here can enhance task assessment based on the duration of flexion exposures. More generally, results demonstrate the importance of considering prior trunk exposures when assessing risk factors for lifting tasks. The proposed solution incorporates “time” as an independent variable, in addition to lifting weight and posture, to better assess spinal loads and maximum lifting capacity based on prior loadings. The current results also suggest that existing ergonomic guidelines or biomechanical models that do not incorporate the viscoelasticity of soft tissues or time-dependent neuromuscular alterations may underestimate spine forces and potential injury risk in some circumstances. To account for this, especially when assessing spine forces during lifting after exposure to prolonged flexion, additional safety margins should be considered. TECHNICAL ABSTRACT Background: Prolonged trunk flexion decreases soft tissue stiffness due to viscoelastic deformations and can also lead to altered kinematics when performing a subsequent lifting task. Yet, it remains to be determined if or how these changes and alterations might increase spine forces. Purpose: A previously developed viscoelastic model was used, along with experimental data, to predict changes in peak spine forces during a lifting task performed following a prolonged flexion exposure (creep). Methods: Model inputs were obtained from an experiment using ten participants, within which lifting kinematics and muscle activity were measured both before and after creep exposure. Two sets of simulations were performed; one in which kinematics were assumed to be unchanged by creep exposure and the other incorporating measured changes in kinematics following exposure. Results: Post-exposure changes in lifting kinematics involved a reduction in the peak relative sagittal-plane flexion of superior lumbar motion segments and an increase in these flexion among inferior lumbar motion segments. Creep exposure caused increases in predicted peak spine forces during lifting at all levels of the lumbar spine (65–241 N). A substantial portion (∼51%) of this increase was estimated to be the result of muscular compensations for reduced passive tissue stiffness. Conclusions: The current study demonstrates that both changes in lifting kinematics and viscoelastic deformations resulting from creep exposures can lead to increased trunk muscle forces and spine forces during a lifting task. This evidence suggests a potential mechanical basis for previous epidemiological evidence that indicates an increased risk of low back disorders for jobs involving both trunk flexion and lifting.
{"title":"Trunk Tissue Creep Can Increase Spine Forces During a Subsequent Lifting Task","authors":"N. Toosizadeh, M. Nussbaum","doi":"10.1080/21577323.2014.956944","DOIUrl":"https://doi.org/10.1080/21577323.2014.956944","url":null,"abstract":"OCCUPATIONAL APPLICATIONS Results from the current study show evidence of an adverse effect of prolonged trunk flexion on spine loads during consecutive lifting tasks. The time-dependent methodology introduced here can enhance task assessment based on the duration of flexion exposures. More generally, results demonstrate the importance of considering prior trunk exposures when assessing risk factors for lifting tasks. The proposed solution incorporates “time” as an independent variable, in addition to lifting weight and posture, to better assess spinal loads and maximum lifting capacity based on prior loadings. The current results also suggest that existing ergonomic guidelines or biomechanical models that do not incorporate the viscoelasticity of soft tissues or time-dependent neuromuscular alterations may underestimate spine forces and potential injury risk in some circumstances. To account for this, especially when assessing spine forces during lifting after exposure to prolonged flexion, additional safety margins should be considered. TECHNICAL ABSTRACT Background: Prolonged trunk flexion decreases soft tissue stiffness due to viscoelastic deformations and can also lead to altered kinematics when performing a subsequent lifting task. Yet, it remains to be determined if or how these changes and alterations might increase spine forces. Purpose: A previously developed viscoelastic model was used, along with experimental data, to predict changes in peak spine forces during a lifting task performed following a prolonged flexion exposure (creep). Methods: Model inputs were obtained from an experiment using ten participants, within which lifting kinematics and muscle activity were measured both before and after creep exposure. Two sets of simulations were performed; one in which kinematics were assumed to be unchanged by creep exposure and the other incorporating measured changes in kinematics following exposure. Results: Post-exposure changes in lifting kinematics involved a reduction in the peak relative sagittal-plane flexion of superior lumbar motion segments and an increase in these flexion among inferior lumbar motion segments. Creep exposure caused increases in predicted peak spine forces during lifting at all levels of the lumbar spine (65–241 N). A substantial portion (∼51%) of this increase was estimated to be the result of muscular compensations for reduced passive tissue stiffness. Conclusions: The current study demonstrates that both changes in lifting kinematics and viscoelastic deformations resulting from creep exposures can lead to increased trunk muscle forces and spine forces during a lifting task. This evidence suggests a potential mechanical basis for previous epidemiological evidence that indicates an increased risk of low back disorders for jobs involving both trunk flexion and lifting.","PeriodicalId":73331,"journal":{"name":"IIE transactions on occupational ergonomics and human factors","volume":"2 1","pages":"71 - 82"},"PeriodicalIF":0.0,"publicationDate":"2014-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21577323.2014.956944","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60124034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-04-03DOI: 10.1080/21577323.2014.964379
Madiha Ahmed, Naira Campbell-Kyureghyan, Karen Frost, G. Bertocci
OCCUPATIONAL APPLICATIONS Wheeled mobility device passengers rely upon bus operators for proper securement of the wheelchair tiedown and occupant restraint system during transit. Yet, wheeled mobility devices are rarely properly secured, and passengers are often unrestrained during transit. This study investigated the usability of wheelchair tiedown and occupant restraint systems aboard transit systems to identify challenges resulting in improper securement or non-use of the wheelchair tiedown and occupant restraint system system. The task demands and bus operator's functional limitations appeared mismatched, jeopardizing the wheeled mobility device user's safety during transit. The current findings suggest the need to incorporate the bus operator's role during subsequent design or redesign of the wheelchair tiedown and occupant restraint system task. TECHNICAL ABSTRACT Rationale: Public transportation buses are required to be equipped with wheelchair tiedowns and occupant restraint systems to ensure safe transit of wheeled mobility device users. Wheeled mobility device users rely upon bus operators for wheeled mobility device securement, yet proper wheelchair tiedown and occupant restraint system implementation is often not performed. Prior research efforts in wheelchair transportation safety have not considered the bus operator's physical health as a challenge to securing a wheeled mobility device passenger. Purpose: The current study characterized musculoskeletal pain and discomfort, along with functional limitations, among bus drivers in the context of assisting wheeled mobility device passengers. Findings from this study were then synthesized with a previously reported ergonomic analysis to provide a more comprehensive understanding of factors that may pose challenges to bus operators securing a wheeled mobility device passenger. Methods: Musculoskeletal pain and functional limitations were determined by self-reports using a customized and standardized questionnaire. Previously reported task demands were quantified by ergonomic analyses of the wheelchair tiedown and occupant restraint system task. Results: Eighty-three percent of the operators reported musculoskeletal pain/discomfort in at least one body region, and 60% reported experiencing pain across multiple regions of the body. The highest number of prevalent reports of pain and functional limitations identified by the operators were at the knees, low back, neck, and shoulders. Ergonomic analyses revealed higher demands for these same four body regions, suggesting limited ability of the operators to perform the wheelchair tiedown and occupant restraint system task properly. Conclusions: The mismatch between the wheelchair tiedown and occupant restraint system work-related factors and the bus operator's functional limitations may contribute to the observed improper securement. These findings suggest a redesign of the wheelchair tiedown and occupant restraint system is warranted, which sh
{"title":"Identifying Challenges to Securing Wheeled Mobility Devices Using Tiedowns and Occupant Restraint Systems From the User Perspective","authors":"Madiha Ahmed, Naira Campbell-Kyureghyan, Karen Frost, G. Bertocci","doi":"10.1080/21577323.2014.964379","DOIUrl":"https://doi.org/10.1080/21577323.2014.964379","url":null,"abstract":"OCCUPATIONAL APPLICATIONS Wheeled mobility device passengers rely upon bus operators for proper securement of the wheelchair tiedown and occupant restraint system during transit. Yet, wheeled mobility devices are rarely properly secured, and passengers are often unrestrained during transit. This study investigated the usability of wheelchair tiedown and occupant restraint systems aboard transit systems to identify challenges resulting in improper securement or non-use of the wheelchair tiedown and occupant restraint system system. The task demands and bus operator's functional limitations appeared mismatched, jeopardizing the wheeled mobility device user's safety during transit. The current findings suggest the need to incorporate the bus operator's role during subsequent design or redesign of the wheelchair tiedown and occupant restraint system task. TECHNICAL ABSTRACT Rationale: Public transportation buses are required to be equipped with wheelchair tiedowns and occupant restraint systems to ensure safe transit of wheeled mobility device users. Wheeled mobility device users rely upon bus operators for wheeled mobility device securement, yet proper wheelchair tiedown and occupant restraint system implementation is often not performed. Prior research efforts in wheelchair transportation safety have not considered the bus operator's physical health as a challenge to securing a wheeled mobility device passenger. Purpose: The current study characterized musculoskeletal pain and discomfort, along with functional limitations, among bus drivers in the context of assisting wheeled mobility device passengers. Findings from this study were then synthesized with a previously reported ergonomic analysis to provide a more comprehensive understanding of factors that may pose challenges to bus operators securing a wheeled mobility device passenger. Methods: Musculoskeletal pain and functional limitations were determined by self-reports using a customized and standardized questionnaire. Previously reported task demands were quantified by ergonomic analyses of the wheelchair tiedown and occupant restraint system task. Results: Eighty-three percent of the operators reported musculoskeletal pain/discomfort in at least one body region, and 60% reported experiencing pain across multiple regions of the body. The highest number of prevalent reports of pain and functional limitations identified by the operators were at the knees, low back, neck, and shoulders. Ergonomic analyses revealed higher demands for these same four body regions, suggesting limited ability of the operators to perform the wheelchair tiedown and occupant restraint system task properly. Conclusions: The mismatch between the wheelchair tiedown and occupant restraint system work-related factors and the bus operator's functional limitations may contribute to the observed improper securement. These findings suggest a redesign of the wheelchair tiedown and occupant restraint system is warranted, which sh","PeriodicalId":73331,"journal":{"name":"IIE transactions on occupational ergonomics and human factors","volume":"2 1","pages":"104 - 94"},"PeriodicalIF":0.0,"publicationDate":"2014-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21577323.2014.964379","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60123953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-01-02DOI: 10.1080/21577323.2014.905884
J. Village, Michael A. Greig, S. Zolfaghari, F. Salustri, W. Neumann
OCCUPATIONAL APPLICATIONS In a longitudinal collaboration with engineers and human factors specialists at an electronics manufacturer, five engineering design tools were adapted to include human factors. The tools, many with required human factors targets, were integrated at each stage of assembly design to increase the proactive application of human factors. This article describes the process of adapting the five tools within the collaborating organization. Findings suggest 12 key features of human factors tools, most importantly that they “fit” with engineering processes, language, and tools; directly address business goals and influence key metrics; and are quantifiable and can demonstrate change. To be effective in an engineering design environment, it is suggested that human factors specialists increase their understanding of their organization's design process, learn which tools are commonly used in engineering, focus on important metrics for the business goals, and incorporate human factors into engineering-based tools and work-system design practices in their organizations. TECHNICAL ABSTRACT Rationale: Design engineers use diverse tools in design, but few incorporate human factors, even though optimizing human performance can further improve operational performance. There is a need for practical tools to help engineers integrate human factors into production design processes. Purpose: This article demonstrates how five engineering design tools were adapted to include human factors and were integrated into design processes within the case study organization. It also provides features of an effective human factors tool and recommendations for practitioners. Method: A longitudinal collaboration with engineers and human factors specialists in a large electronics manufacturing organization allowed in vivo adaptation and testing of various tools in an action research methodology. Qualitative data were recorded from multiple sources, then transcribed and analyzed over a 3-year period. Results: The adapted tools integrated into each stage of the design process included the human factors process failure mode effects analysis, human factors design for assembly, human factors design for fixtures, workstation efficiency evaluator, and human factors kaizens. Each tool had a unique participatory development process; 12 features are recommended for effective human factors tools based on the findings herein. Most importantly, tools should “fit” with existing engineering processes, language, and tools; directly address business goals and influence key metrics; and be quantifiable and demonstrate change. Conclusions: Engineers and management responded positively to the five tools adapted for human factors because they were designed to help improve assembly design and achieve their business goals. Several of the human factors tools became required targets within the design process, ensuring that human factors considerations are built into all future design
{"title":"Adapting Engineering Design Tools to Include Human Factors","authors":"J. Village, Michael A. Greig, S. Zolfaghari, F. Salustri, W. Neumann","doi":"10.1080/21577323.2014.905884","DOIUrl":"https://doi.org/10.1080/21577323.2014.905884","url":null,"abstract":"OCCUPATIONAL APPLICATIONS In a longitudinal collaboration with engineers and human factors specialists at an electronics manufacturer, five engineering design tools were adapted to include human factors. The tools, many with required human factors targets, were integrated at each stage of assembly design to increase the proactive application of human factors. This article describes the process of adapting the five tools within the collaborating organization. Findings suggest 12 key features of human factors tools, most importantly that they “fit” with engineering processes, language, and tools; directly address business goals and influence key metrics; and are quantifiable and can demonstrate change. To be effective in an engineering design environment, it is suggested that human factors specialists increase their understanding of their organization's design process, learn which tools are commonly used in engineering, focus on important metrics for the business goals, and incorporate human factors into engineering-based tools and work-system design practices in their organizations. TECHNICAL ABSTRACT Rationale: Design engineers use diverse tools in design, but few incorporate human factors, even though optimizing human performance can further improve operational performance. There is a need for practical tools to help engineers integrate human factors into production design processes. Purpose: This article demonstrates how five engineering design tools were adapted to include human factors and were integrated into design processes within the case study organization. It also provides features of an effective human factors tool and recommendations for practitioners. Method: A longitudinal collaboration with engineers and human factors specialists in a large electronics manufacturing organization allowed in vivo adaptation and testing of various tools in an action research methodology. Qualitative data were recorded from multiple sources, then transcribed and analyzed over a 3-year period. Results: The adapted tools integrated into each stage of the design process included the human factors process failure mode effects analysis, human factors design for assembly, human factors design for fixtures, workstation efficiency evaluator, and human factors kaizens. Each tool had a unique participatory development process; 12 features are recommended for effective human factors tools based on the findings herein. Most importantly, tools should “fit” with existing engineering processes, language, and tools; directly address business goals and influence key metrics; and be quantifiable and demonstrate change. Conclusions: Engineers and management responded positively to the five tools adapted for human factors because they were designed to help improve assembly design and achieve their business goals. Several of the human factors tools became required targets within the design process, ensuring that human factors considerations are built into all future design","PeriodicalId":73331,"journal":{"name":"IIE transactions on occupational ergonomics and human factors","volume":"2 1","pages":"1 - 14"},"PeriodicalIF":0.0,"publicationDate":"2014-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21577323.2014.905884","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60123581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-01-02DOI: 10.1080/21577323.2014.908793
A. Chambers, Elizabeth A. Harchick, R. Cham
OCCUPATIONAL APPLICATIONS This study provides the first description of gait changes after a slip experience with no threat of additional slippery surfaces. The age-related differences found after experiencing an unexpected slip provide valuable information that should be considered when designing slip paradigms, slip-prevention measures, and the workplace. Specifically, the possibility of generating more than one unexpected slip would allow researchers to further investigate this unique event to prevent falls in the workplace. It is important to understand how frictional requirements and other gait adaptations are impacted by experiencing a slip to ensure that ergonomic interventions, such as shoe–floor design, slip-prevention training, and warning systems, can be effective. Safety warning systems should also be a focus of slip prevention in the workplace, since experiencing a slip alone may not have a long-lasting effect on gait adaptations that could minimize future slip risk, especially in young adults. TECHNICAL ABSTRACT Background: High injury rates and costs associated with occupational falls make them an important prevention target. Purpose: The goal of this study was to examine the impact of experiencing a slip on the peak required coefficient of friction during subsequent gait trials in which subjects were informed that the floor was no longer slippery. Methods: Twenty-seven young (20–31 years) and 25 older adults (50–65 years) walked across a dry floor (baseline dry) then experienced an unexpected slip. Following this, 15 dry trials (recovery dry) and a second unexpected slip were completed. Required coefficient of friction and general spatiotemporal gait parameters were derived during walking on dry surfaces. Results: Young adults initially reduced their peak required coefficient of friction on the left (previously slipped) foot but, after being informed that the floor was no longer slippery, eventually returned to within baseline levels of peak required coefficient of friction and walked with faster gait and longer steps. Young adults exhibited a second slip of similar magnitude to their first slip. Older adults continued walking more cautiously, with a decreased peak required coefficient of friction and other gait adaptations, after experiencing a slip, even though there was no threat of a subsequent slip. With this cautious gait, older adults experienced over a 40% decrease in peak slip velocity in the second slip event. Conclusions: The age-related differences found after experiencing an unexpected slip provide valuable information that should be considered when designing slip paradigms, slip-prevention measures, and the workplace. The possibility of generating more than one unexpected slip would allow researchers to further investigate this unique event to prevent falls in the workplace. It is important to understand how frictional requirements and other gait adaptations are impacted by experiencing a slip, to ensure that ergonomi
{"title":"Shoe–Floor Frictional Requirements During Gait after Experiencing an Unexpected Slip","authors":"A. Chambers, Elizabeth A. Harchick, R. Cham","doi":"10.1080/21577323.2014.908793","DOIUrl":"https://doi.org/10.1080/21577323.2014.908793","url":null,"abstract":"OCCUPATIONAL APPLICATIONS This study provides the first description of gait changes after a slip experience with no threat of additional slippery surfaces. The age-related differences found after experiencing an unexpected slip provide valuable information that should be considered when designing slip paradigms, slip-prevention measures, and the workplace. Specifically, the possibility of generating more than one unexpected slip would allow researchers to further investigate this unique event to prevent falls in the workplace. It is important to understand how frictional requirements and other gait adaptations are impacted by experiencing a slip to ensure that ergonomic interventions, such as shoe–floor design, slip-prevention training, and warning systems, can be effective. Safety warning systems should also be a focus of slip prevention in the workplace, since experiencing a slip alone may not have a long-lasting effect on gait adaptations that could minimize future slip risk, especially in young adults. TECHNICAL ABSTRACT Background: High injury rates and costs associated with occupational falls make them an important prevention target. Purpose: The goal of this study was to examine the impact of experiencing a slip on the peak required coefficient of friction during subsequent gait trials in which subjects were informed that the floor was no longer slippery. Methods: Twenty-seven young (20–31 years) and 25 older adults (50–65 years) walked across a dry floor (baseline dry) then experienced an unexpected slip. Following this, 15 dry trials (recovery dry) and a second unexpected slip were completed. Required coefficient of friction and general spatiotemporal gait parameters were derived during walking on dry surfaces. Results: Young adults initially reduced their peak required coefficient of friction on the left (previously slipped) foot but, after being informed that the floor was no longer slippery, eventually returned to within baseline levels of peak required coefficient of friction and walked with faster gait and longer steps. Young adults exhibited a second slip of similar magnitude to their first slip. Older adults continued walking more cautiously, with a decreased peak required coefficient of friction and other gait adaptations, after experiencing a slip, even though there was no threat of a subsequent slip. With this cautious gait, older adults experienced over a 40% decrease in peak slip velocity in the second slip event. Conclusions: The age-related differences found after experiencing an unexpected slip provide valuable information that should be considered when designing slip paradigms, slip-prevention measures, and the workplace. The possibility of generating more than one unexpected slip would allow researchers to further investigate this unique event to prevent falls in the workplace. It is important to understand how frictional requirements and other gait adaptations are impacted by experiencing a slip, to ensure that ergonomi","PeriodicalId":73331,"journal":{"name":"IIE transactions on occupational ergonomics and human factors","volume":"2 1","pages":"15 - 26"},"PeriodicalIF":0.0,"publicationDate":"2014-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21577323.2014.908793","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60123746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-01-02DOI: 10.1080/21577323.2014.912695
Rajesh Raghunathan, J. Maiti, B. Samanta
OCCUPATIONAL APPLICATIONS In this study, a biomechanical exposure assessment methodology for combined manual material handling tasks is devised using the “cube” model approach (including time, force, and posture), specifically by modifying the model dimensions. The resulting modified cube model aims to facilitate biomechanical exposure assessment of manual material handling tasks, particularly for industrial conditions where a chain of combined manual material handling activities is carried out across a wide geographical area, and where no direct measurements of biomechanical exposures are available. This methodology can help in prioritizing high-exertion manual material handling tasks for subsequent ergonomic analysis and redesign. TECHNICAL ABSTRACT Background: Biomechanical exposure measurement is difficult for combined manual material handling tasks in field settings and/or resource-constrained environments. “Cube” models—integrating time, force, and posture—have been used previously, but existing models have not been applied to manual material handling tasks. Purpose: The objective of this study was to develop a revised cube model as a biomechanical exposure assessment tool for combined manual material handling tasks. Methods: The study was conducted in a bearing manufacturing plant in India. First, a work-sampling approach was used to observe all manual material handling tasks and record relevant details. Then, two modified models—cube model 1 and cube model 2—were developed by modifying the existing cube model dimensions; physical load intensity and overall physical load were calculated using these two models under a novel cumulative exposure measurement framework. Decision criteria for cumulative cube score were formulated to classify manual material handling tasks under three physical load levels (i.e., low, medium, and high). Finally, cube model assessments were compared with biomechanical assessments of all manual material handling tasks. Results: Attribute agreement (overall correct classification) values for the existing cube model, cube model 1, and cube model 2 were 39%, 61%, and 69%, respectively, indicating better performance for cube model 2. Spearman rank order correlations comparing cumulative cube scores with cumulative biomechanical measures ranged from 0.73 to 0.94, which is considered to be high. Conclusions: The study presents a methodology to assess biomechanical exposures for combined manual material handling tasks by modifying the existing cube model. A cumulative dose concept as applied in biomechanical analysis was used in the study. The cumulative cube score is proposed as a proxy to indicate the overall biomechanical exposure during a combined manual material handling task. Cumulative cube scores gave good agreement between cube model 2 evaluations and biomechanical evaluations, supporting its applicability for evaluating manual material handling tasks.
{"title":"Application of the Cube Model for Biomechanical Exposure Assessment of Combined Manual Material Handling Tasks in a Manufacturing Plant in India","authors":"Rajesh Raghunathan, J. Maiti, B. Samanta","doi":"10.1080/21577323.2014.912695","DOIUrl":"https://doi.org/10.1080/21577323.2014.912695","url":null,"abstract":"OCCUPATIONAL APPLICATIONS In this study, a biomechanical exposure assessment methodology for combined manual material handling tasks is devised using the “cube” model approach (including time, force, and posture), specifically by modifying the model dimensions. The resulting modified cube model aims to facilitate biomechanical exposure assessment of manual material handling tasks, particularly for industrial conditions where a chain of combined manual material handling activities is carried out across a wide geographical area, and where no direct measurements of biomechanical exposures are available. This methodology can help in prioritizing high-exertion manual material handling tasks for subsequent ergonomic analysis and redesign. TECHNICAL ABSTRACT Background: Biomechanical exposure measurement is difficult for combined manual material handling tasks in field settings and/or resource-constrained environments. “Cube” models—integrating time, force, and posture—have been used previously, but existing models have not been applied to manual material handling tasks. Purpose: The objective of this study was to develop a revised cube model as a biomechanical exposure assessment tool for combined manual material handling tasks. Methods: The study was conducted in a bearing manufacturing plant in India. First, a work-sampling approach was used to observe all manual material handling tasks and record relevant details. Then, two modified models—cube model 1 and cube model 2—were developed by modifying the existing cube model dimensions; physical load intensity and overall physical load were calculated using these two models under a novel cumulative exposure measurement framework. Decision criteria for cumulative cube score were formulated to classify manual material handling tasks under three physical load levels (i.e., low, medium, and high). Finally, cube model assessments were compared with biomechanical assessments of all manual material handling tasks. Results: Attribute agreement (overall correct classification) values for the existing cube model, cube model 1, and cube model 2 were 39%, 61%, and 69%, respectively, indicating better performance for cube model 2. Spearman rank order correlations comparing cumulative cube scores with cumulative biomechanical measures ranged from 0.73 to 0.94, which is considered to be high. Conclusions: The study presents a methodology to assess biomechanical exposures for combined manual material handling tasks by modifying the existing cube model. A cumulative dose concept as applied in biomechanical analysis was used in the study. The cumulative cube score is proposed as a proxy to indicate the overall biomechanical exposure during a combined manual material handling task. Cumulative cube scores gave good agreement between cube model 2 evaluations and biomechanical evaluations, supporting its applicability for evaluating manual material handling tasks.","PeriodicalId":73331,"journal":{"name":"IIE transactions on occupational ergonomics and human factors","volume":"2 1","pages":"39 - 51"},"PeriodicalIF":0.0,"publicationDate":"2014-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21577323.2014.912695","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60124134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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