Handling Of Heavy Loads Research Articles

Improving Ergonomics in the Meat Industry: A Case Study of an Italian Ham Processing Company

Meat processing is a labor-intensive industry dealing with manual handling of heavy loads of meat at high frequency. Meat processing workers are under pressure to maintain high rates of work, performing arduous repetitive motions while keeping awkward postures. Ergonomic risk assessments reveal that manual material handling and repetitive tasks expose meat-processing workers to high physical risk. This paper investigates the impact of automated technology on manual ham-deboning lines in the meat-processing industry. The aim is to study the effects of automation on the work system and layout, analyzing the economic and ergonomic impact of semi-automatic ham deboning lines. The study introduces a non-safety cost model for the comparative and sensitive analysis of manual and semiautomatic ham deboning systems, including the cost of non-safety. The model is tested with a case study from an Italian ham processing company. The reference manual ham-deboning line is introduced, together with a new layout proposal involving the adoption of a semi-automatic ham-deboning machine. Results reveal the positive impact of the semi-automatic ham-deboning system on the company's profitability and workers’ ergonomics. As a consequence, automated technology leads to economic and ergonomic benefits for workers, employers and customers.

The Body Extender: A Full-Body Exoskeleton for the Transport and Handling of Heavy Loads

This article introduces and describes an electrically powered full-body (FB) exoskeleton, called the body extender (BE), intended as a research platform for the study of the transport and handling of heavy loads up to 50 kg, with one hand at worst-load conditions (WLCs). The machine features a 22-degrees-of-freedom (DoF) quasi-anthropomorphic kinematic scheme and a modular hardware/software architecture that made it possible to manage the complexity of the system design. Besides providing a context and some general guidelines, which have driven the design of the BE, this article presents the hardware and software developments that have been achieved and implemented in the machine. The experimental results are shown that prove the functionalities of the BE in common operating conditions such as walking, squatting, and handling loads. The one-of-a-kind system demonstrates, in relevant laboratory settings, the feasibility of a complex, electrically powered full-body exoskeleton with such a target payload.

Cumulative mechanical low-back load at work is a determinant of low-back pain

ObjectivesReported associations of physical exposures during work (eg, lifting, trunk flexion or rotation) and low-back pain (LBP) are rather inconsistent. Mechanical back loads (eg, moments on the low back) as...

Occupational lifting during pregnancy and child’s birth size in a large cohort study

It has been suggested that the handling of heavy loads during pregnancy is associated with impaired fetal growth. We examined the association between quantity and frequency of maternal occupational lifting and the child's size at birth, measured by weight, length, ponderal index, small-for-gestational-age (SGA), abdominal circumference, head circumference, and placental weight. We analyzed birth size from the Danish Medical Birth Registry of 66 693 live-born children in the Danish National Birth Cohort according to the mother's self-reported information on occupational lifting from telephone interviews around gestational week 16. Data were collected in the period 1996-2002. We used linear and logistic regression models and adjusted for confounders. In the fully adjusted models, most of the mean differences in birth size measures had values indicating a smaller size of offspring among women with occupational lifting versus women with no lifting, but the differences were very small, and there was a statistically significant trend only for placental weight showing lighter weight with increasing number of kilos lifted per day. In jobs likely to include person-lifting, we found increased odds of SGA among children of women who lifted 501-1000 kilos per day [odds ratio (OR) 1.34, 95% confidence interval (95% CI) 0.98-1.83] and >1000 kilos per day (OR 1.51, 95% CI 0.83-2.76) compared to no lifting. In jobs with no person-lifting, occupational lifting was not associated with SGA. Overall, we observed no strong support for an association between maternal occupational lifting and impaired size at birth. Our data indicated a potential association between lifting and SGA among offspring of women in occupations that are likely to include person-lifting. These results should, however, be interpreted with caution due to limited statistical power, and we suggest that future studies include detailed, individual information on job functions and ergonomic routines of lifting procedures.

An Innovative Idea for Reducing the Musculoskeletal Disorders in Drywall Installation

Objective: The study was conducted to assess an intervention suggested by the workers to reduce the ergonomic exposures of the drywall installation task. Methods: At several focus group meetings the drywall installers were asked to brainstorm on innovative ideas that could reduce their ergonomic/musculoskeletal exposures during the drywall installation work. The workers discussed the idea of using a ‘deadman’ (long narrow piece of sheetrock) to help hold the panels on the ceiling while installing them. The researcher collected quantitative exposure data (PATH, 3DSSPP) at the baseline and intervention phases. The data at the two time periods were compared to find out any change in the exposure with use of the ‘deadman’. Results: Results showed that exposures (such as overhead arm and awkward trunk postures and heavy load handling) were reduced in the intervention phase while using an electrical lift and the ‘deadman’. Conclusion: The concept of the ‘deadman’, which was shown to help reduce musculoskeletal exposures during ceiling installation, can be used to fabricate a permanent ergonomic tool to support the ceiling sheetrock.

Musculoskeletal disorders among Tunisian hospital staff: Prevalence and risk factors

Aim of the workMusculoskeletal disorders (MSD) represent a significant occupational problem among hospital staff; however, data on musculoskeletal health of hospital staff are sparse. This study sought to determine the prevalence of MSD, their epidemiologic data and the associated risk factors. MethodsA previously self administered questionnaire sought information on demographics, prevalence and pattern of MSD, associated risk factors was employed as the survey instrument. A total of 520 questionnaires were distributed to hospital staff but only 433 questionnaires was valid. Eighty-seven of the returned questionnaires were excluded because of incomplete data. ResultsThe prevalence of MSD among hospital staff was 65.4%. Musculoskeletal disorders occurred mostly in low back (74.5%), neck (38.1%), and knees (31.1%).Factors associated to MSD were age (P<0.001), female gender (P<0.001), years of service (P<0.001) as well as prolonged standing or sitting (P=0.016 and 0.023, respectively). No significant association was found between repetitive movement, uncomfortable postures, heavy load handling, working on night shifts, stress and the presence of MSD. ConclusionA high proportion of hospital staff reported MSD at some body site with the low back being injured most often. Education programs on prevention and coping strategies for musculoskeletal disorders are recommended for hospital staff in order to reduce the rate of occupational hazards and also promote efficiency in patient care.

Feedback Linearization-Based Position Control of an Electrohydraulic Servo System With Supply Pressure Uncertainty

Electrohydraulic servo systems (EHSS) are used for several engineering applications, and in particular, for efficient handling of heavy loads. proportional-integral-differential (PID) control is used extensively to control EHSS, but the closed-loop performance is limited using this approach, due to the nonlinear dynamics that characterize these systems. Recent studies have shown that feedback linearization is a viable control design technique that addresses the nonlinear dynamics of EHSS; however, it is important to establish the robustness of this method, given that hydraulic system parameters can vary significantly during operation. In this study, we focus on supply pressure variations in a rotational electrohydraulic drive. The supply pressure appears in a square-root term in the system model, and thus, standard adaptive techniques that require uncertain parameters to appear linearly in the system equations, cannot be used. A Lyapunov approach is used to derive an enhanced feedback-linearization-based control law that accounts for supply pressure changes. Simulation results indicate that standard feedback-linearization based control is robust to EHSS parameter variations, providing significant improvement over PID control, and that the performance can be further improved using the proposed control law.

Work-Related Musculoskeletal Complaints Among Workers of Iranian Aluminum Industries

ABSTRACT In developing countries, musculoskeletal complaints are considered as main cause of occupational complications and disability. Economic burden of these complications more than workers has impact on organization and society in general. In Iranian aluminum industries, workers are directly involved in production process and physical activities such as manual material handling and awkward postures are very common. The present study was performed for assessment of musculoskeletal complaints prevalence among workers of Iranian aluminum industries. Participants in this cross-sectional study were 493 workers of 3 Iranian aluminum industries with random selection. Data of musculoskeletal complaints were gathered by means of the standardized Nordic self-reporting questionnaire. Demographic and work-related data were collected into the checklist. Findings of this study showed that 65.5% of workers in past week and 77.5% of workers in past year had claimed one of the musculoskeletal complaints in their work places. Lumbar, knee(s), and upper back had the most musculoskeletal complaints prevalence in participants. Musculoskeletal complaints in past week and year had significant association with job duration and age in these workers. Musculoskeletal complaints in Iranian aluminum industries happened in high rate. Ergonomic intervention strategies in the workplaces must be the focus for elimination of environmental hazards such as apposition on the time of work and manual handling of heavy loads.

流れ作業における主観的作業速度評価と職業性腰痛リスクとの関連

It is possible that the performance rating of line workers is affected by the risk factors for musculoskeletal disorders that are included in their work more so than by the actual takt time. To investigate whether performance rating relates to the risk factors for musculoskeletal disorders, we analyzed a dataset obtained from a self-administered questionnaire answered by assembly line workers (n=1579). As a result, performance rating had a significant association with unsuitable work environments, poor working postures and handling of heavy loads. The workers who reported the fastest rating had a higher exposure than others to the risk factors for occupational low back pain. The results of our study support the effectiveness of performance rating as an index of work burden.

Adaptive Position Control of an Electrohydraulic Servo System With Load Disturbance Rejection and Friction Compensation

Electrohydraulic servo systems (EHSS) are used for several engineering applications, and in particular, for efficient handling of heavy loads. These systems are characterized by pronounced nonlinearities and are also subject to parameter variations during operation, friction effects, and variable loads. Several studies have addressed the nonlinear nature of EHSS; however, only a few control schemes explicitly address friction and load disturbance effects along with parameter variations. Fuzzy and/or sliding mode versions of feedback linearizing controllers have been used to compensate for the external loads disturbances in the control of EHSS. However, real-time implementations issues limit the use of these techniques. While adaptive control using a feedback-linearization based controller structure has been shown to be effective in the presence of parameter variations, load and friction effects are typically not considered. In this paper, we present a nonlinear adaptive feedback linearizing position controller for an EHSS, which is robust to parameter uncertainty while achieving load disturbances rejection/attenuation and friction compensation. The adaptation law is derived using a Lyapunov approach. Simulation results using the proposed controller are compared to those using a nonadaptive feedback linearizing controller as well as a proportional-integral-derivative (PID) controller, in the presence of torque load disturbance, friction, and uncertainty in the hydraulic parameters. These results show improved tracking performance with the proposed controller. To address implementation concerns, simulation results with noise effects and valve saturation are also presented.

Low back pain around retirement age and physical occupational exposure during working life

BackgroundPhysical occupational exposure is a risk factor for low back pain in workers but the long term effects of exposure remain unclear. As several countries consider increasing the retirement age, further information on this topic is relevant. This study aimed to describe the prevalence of low back pain among middle aged and aging individuals in the general French population according to physical occupational exposure and retirement status.MethodsThe study population originated from the French national survey 'Enquête décennale santé 2002'. Low back pain for more than 30 days within the previous twelve months (LBP) was assessed using a French version of the Nordic questionnaire. Occupational exposure was self assessed. Subjects were classified as "exposed" if they were currently or had previously been exposed to handling of heavy loads and/or to tiring postures. The weighted prevalence of LBP was computed separately for men and women, for active (aged 45-59) and retiree (aged 55-74), according to 5-year age group and past/present occupational exposure.ResultsFor active men, the prevalence of LBP was significantly higher in those currently or previously exposed (n = 1051) compared with those never exposed (n = 1183), respectively over 20% versus less than 11%. Among retired men, the prevalence of LBP tended towards equivalence with increasing age among those previously exposed (n = 748) and those unexposed (n = 599).Patterns were quite similar for women with a higher prevalence in exposed active women (n = 741) compared to unexposed (n = 1260): around 25% versus 15%. Similarly, differences between previously exposed (n = 430) and unexposed (n = 489) retired women tended to reduce with age.ConclusionThe prevalence of LBP in active workers was associated with occupational exposure. The link with past exposure among retirees decreased with age. These results should be considered for policies dealing with prevention at the workplace and retirement.

Evaluación de factores de riesgos asociados al manejo manual de carga

La Ley N° 20.001, del Libro II del Código del Trabajo de Chile del año 2005 define: que el peso máximo de carga humana es de 50 Kg., la obligatoriedad por parte del empleador de incorporar los medios mecánicos necesarios que eviten la manipulación manual de carga, y por último la capacitación a los trabajadores en esta materia.La Escuela de Terapia Ocupacional de la Universidad Mayor, realiza el año 2007, en una empresa metalúrgica ligada a la minería metálica, un diagnóstico respecto de factores de riesgo asociados al manejo manual de carga en las áreas productivas y de servicios en dicha empresa, y así dar cumplimiento a la legislación, conocer con mayor precisión las condiciones reales del manejo manual de carga dentro de la empresa y su posible impacto en la adquisición de lesiones o enfermedades músculo esqueléticas en los trabajadores. Para ello se utilizan dos metodologías de evaluación, el análisis de puesto de trabajo y el software Ergocargas, combinando estrategias de carácter cualitativo y cuantitativo respectivamente. Como parte de sus principales resultados se identifica que la conducta de trabajadores y la organización del trabajo constituyen aquellos factores de riesgo más relevantes. Por otra parte se destaca la importancia de abordar esta temática dentro de la empresa de manera trasversal entre los diversos departamentos que la componen es imprescindible para garantizar el control de los factores de riesgos asociados.

Prévenir les troubles musculosquelettiques chez les soignants : connaître les expositions et étude des outils d’aide à la manutention

Summary Aim of the study The occupational hazard evaluation and prevention program aimed to propose specific hospital programs and risk assessment tools for the French University Hospitals networks. Studies regarding the prevention of musculoskeletal disorders (MSDs) were mostly based on the combined expertise in ergonomics, epidemiology and industrial medicine of the University Hospitals of Angers and Grenoble. Method An initial epidemiological study identified the main risk factors for upper-extremity MSDs and low back pain in the hospital healthcare workers. The second study focused on the ergonomic assessment of assistive equipments for patient handling. Results Hospital workers were exposed to 2.4 of the 19 documented risk factors (3.5 for the general population of the region), but did not suffer from more MSDs of the upper limbs than salaried workers of the Pays de la Loire region. However, exposure to manual handling of heavy loads during patient care was more frequent. The technical equipment available to assist in-patient handling were most often not adapted to the criteria of patient dependence and/or the work organisation of the health services. The patient–equipment relationships, the usability of the devices and the psychological point of view of the hospital workers must be taken into account for the prevention. Conclusion This pilot investigation involved biomechanical processes forming part of a multidisciplinary preventive approach integrated into institution policy.

Level of education and back pain in France: the role of demographic, lifestyle and physical work factors.

To investigate the pathways from level of education to low back pain (LBP) in the adult population, especially concerning the role of physical working constraints, and personal factors (overweight, tobacco consumption, and tallness). The study population consisted of 15,534 subjects from the National Health Survey, with data on LBP, level of education, personal factors, and physical working constraints. Logistic models for LBP (pain more than 30 days during the previous 12 months) were compared in order to check the consistency of the data with specific causal pathways. Low back pain was strongly associated with level of education. This association was almost completely explained if present or past exposure to tiring work postures and handling of heavy loads were taken into account. For men, the OR for "no diploma", adjusted only for age, was 1.75; it was 1.02 after additional adjustment on physical work factors. Personal factors played also a role, especially overweight for women. Among them, the OR associated with a body mass index = 27 or more was 1.58 after adjustment on all the other factors. In this national population the main pathways from education to LBP were through occupational exposure and lifestyle factors.

Remote handling dynamical modelling: Assessment of a new approach to enhance positioning accuracy with heavy load manipulation

In-vessel maintenance work in Fusion Tokamak will be carried out by the help of several sets of robotic devices. Handling of heavy loads in constrained space is identified by all players of the RH community as a key-issue in behalf of the ITER. To deal with high-level dexterity tasks, characterized by high payload to mass ratio and limited operating space RH equipment designers propose systems whose mechanical flexibility is no longer negligible and needs to be taken into account in the control scheme. A traditional approach where control system includes a linear model of deformation of the structure only leads to poor positioning accuracy. During maintenance operations in the ITER facility, uncontrolled or under-evaluated errors can damage in-vessel components. To address the control of complex flexible systems, we will investigate the use of specific mechanical software that combines both finite element and kinematical joint analyses with a strong-coupled formulation to perform system dynamics simulations. This approach will be applied to a single axis mock-up of robotic joint, supplied by a highly flexible structure. A comparison of experimental results with the traditional linear approach and the specified software model is carried out.

Selected questions on biomechanical exposures for surveillance of upper-limb work-related musculoskeletal disorders.

Questionnaires for assessment of biomechanical exposure are frequently used in surveillance programs, though few studies have evaluated which key questions are needed. We sought to reduce the number of variables on a surveillance questionnaire by identifying which variables best summarized biomechanical exposure in a survey of the French working population. We used data from 2002 to 2003 French experimental network of Upper-limb work-related musculoskeletal disorders (UWMSD), performed on 2,685 subjects in which 37 variables assessing biomechanical exposures were available (divided into four ordinal categories, according to the task frequency or duration). Principal Component Analysis (PCA) with orthogonal rotation was performed on these variables. Variables closely associated with factors issued from PCA were retained, except those highly correlated to another variable (rho > 0.70). In order to study the relevance of the final list of variables, correlations between a score based on retained variables (PCA score) and the exposure score suggested by the SALTSA group were calculated. The associations between the PCA score and the prevalence of UWMSD were also studied. In a final step, we added back to the list a few variables not retained by PCA, because of their established recognition as risk factors. According to the results of the PCA, seven interpretable factors were identified: posture exposures, repetitiveness, handling of heavy loads, distal biomechanical exposures, computer use, forklift operator specific task, and recovery time. About 20 variables strongly correlated with the factors obtained from PCA were retained. The PCA score was strongly correlated both with the SALTSA score and with UWMSD prevalence (P < 0.0001). In the final step, six variables were reintegrated. Twenty-six variables of 37 were efficiently selected according to their ability to summarize major biomechanical constraints in a working population, with an approach combining statistical analyses and existing knowledge.

Physical Requirements Associated With the Work of Aging Workers in the European Union

Physical requirements of work should decline with advancing age because the dimensions of physical work capacity of individuals decline with age, too. The Second European Survey on Working Conditions in 1995/1996 was used to study the prevalences (%) of poor work postures, handling heavy loads, and repetitive work in the representative sample of employed people in the 15 European Union member states. Exposure to physical requirements was still common in the European Union. Nearly 50% of older workers (age 45 years or more) were exposed to repetitive work, about 30% had poor work postures and 15% to 20% were handling heavy loads at least half of the working time. The physical requirements were as common for older and younger (less than 45 years of age) workers. The physical requirements were most common in Mediterranean countries and least common in the northern part of Europe. The differences in prevalence rates of exposures between the countries were large, from three- to fivefold. Favorable differences between older and younger workers were more notable for older men than for older women in poor work postures and repetitive work. However, older women had less handling of heavy loads than older men. The results showed that the need for better adjustments of physical requirements with age is still very relevant in the European Union and demands urgently appropriate measures in working life.

Development of a Heavy Load Handling Robot and Its Electric-Pneumatic Driving Mechanism

A number of industrial robots have been used in various work task from small parts assembly jobs to heavy load handling ones. To handle heavy load, the manipulator becomes heavy because the payload to wight(p/w) ratio of the conventional robots is very low. In this research, a heavy load handling manipulator whose p/w ratio is over 1/4 was designed and fabricated. An electric-pneumatic driving mechanism was also developed to achieve fme positioning accuracy with heavy payload. The combined driving mechanism was implemented and tested in several aspects.

Reduction of farmers' postural load during occupationally oriented medical rehabilitation

Farmers' back problems may be associated with the amount of back flexion and the handling of heavy loads. The aim of this study was to analyse the effects of occupationally oriented medical rehabilitation courses on female farmers' postural load. Twenty seven female farmers (aged from 32 to 52 years) took part in four rehabilitation courses at one rehabilitation centre in Finland. The subjects suffered from various musculoskeletal symptoms, which decreased their work ability. The rehabilitation courses included two periods: the first lasted for 3 weeks and the latter for 1 week, organized 6 months after the first period. The work postures and their load on the musculoskeletal system were classified by the computerized OWAS method in three daily work phases. During the 3-week periods new work techniques were learned, and simultaneous bent and twisted postures for the back decreased from 34 to 4% of all studied work postures. Similarly, postures with one or both arms above shoulder level were reduced from 44 to 24%. Rechecking after the 6-month period confirmed that the adoption of new work techniques was consistent. The study showed that female farmers could change their work techniques during this kind of intensive rehabilitation period, and the changes were seen 6 months later in the follow-up.

Job analysis at ARBED

Ergonomic job analyses are applied at ARBED since 1960. In the first years they were mainly based on physiological stress measurements. But in recent years newly developed standardized ergonomic analyses were tested and used to complete or even substitute the classical ergonomic methods. Two standardized methods, which are actually used currently at ARBED, are presented: the ‘Profils de Postes’ (job profiles); and the ‘Arbeitswissenschaftliches Erhebungsverfahren zur Taetigkeitsa-nalyse’ AET (ergonomic method for job analysis). The principles and possibilities of both methods are explained and their utilities are shown on a practical analysis of a job, involving the handling of heavy loads.