Changing from batch to flow assembly in the production of emergency lighting devices.

Current assembly enterprises are under a lot of pressure, as they are faced with increasing volume demands and product variations, needs for shorter delivery times and cost reduction. This pressure is likely to increase the pressure on individual workers. In many small to medium-sized enterprises (SMEs), we observe that traditional assembly concepts are no longer fulfilled. These are challenged to find other concepts to meet today's demands. In a company where emergency lighting devices are assembled in batches (large series of products are assembled step by step), we applied a participatory and integrative approach to set up a mixed flow assembly system including ergonomically designed work stations. In this paper, we describe the approach and the effects which were studied by a within-subject design. We observed an increase of 44% in productivity and a reduction in order lead time of 46%. The time that workers spent to added-value activities increased significantly from 74% to 92%, without any increase in postural and experienced loads. Instead, the workers experienced significantly less overall fatigue at the end of the day in the new situation. The results show the potential benefits of the approach for the many SMEs where products are assembled in batches and faced with the problem of meeting current production demands. © 2005 Taylor & Francis Group Ltd

Factors underlying the perturbation resistance of the trunk in the first part of a lifting movement

In the first part of lifting movements, the trunk movement is surprisingly resistant to perturbations. This study examined which factors contribute to this perturbation resistance of the trunk during lifting. Three possible mechanisms were studied: force-length-velocity characteristics of muscles, the momentum of the trunk as well as the effect of passive extending of the elbows. A forward dynamics modelling and simulation approach was adopted with two different input signals: (1) stimulation of Hill-type muscles versus (2) net joint moments. Experimental data collected during an unperturbed lifting movement were used as a reference, which a simulated lifting movement had to resemble. Subsequently, the simulated lifting movement was perturbed by applying 10 kg extra mass at the wrist (both before and after lift-off and with/without a fixed elbow), without modifying the input signals. The momentum of the trunk appeared to be insufficient to explain the perturbation resistance of trunk movements as found experimentally. In addition to the momentum of the trunk, the force-length-velocity characteristics of the muscles are necessary to account for the observed perturbation resistance. Initial extension of the elbow due to the mass perturbation delayed the propagation of the load to the shoulder. However, this delay is reduced due to the impedance at the elbow provided by the characteristics of muscles spanning the elbow. So, the force-length-velocity characteristics of the muscles spanning the elbow joint increase the perturbation at the trunk. © Springer-Verlag 2005

Cumulative Low Back Load at Work as a Risk Factor of Low Back Pain: A Prospective Cohort Study

Purpose Much research has been performed on physical exposures during work (e.g. lifting, trunk flexion or body vibrations) as risk factors for low back pain (LBP), however results are inconsistent. Information on the effect of doses (e.g. spinal force or low back moments) on LBP may be more reliable but is lacking yet. The aim of the present study was to investigate the prospective relationship of cumulative low back loads (CLBL) with LBP and to compare the association of this mechanical load measure to exposure measures used previously. Methods The current study was part of the Study on Musculoskeletal disorders, Absenteeism and Health (SMASH) study in which 1,745 workers completed questionnaires. Physical load at the workplace was assessed by video-observations and force measurements. These measures were used to calculate CLBL. Furthermore, a 3-year follow-up was conducted to assess the occurrence of LBP. Logistic regressions were performed to assess associations of CLBL and physical risk factors established earlier (i.e. lifting and working in a flexed posture) with LBP. Furthermore, CLBL and the risk factors combined were assessed as predictors in logistic regression analyses to assess the association with LBP. Results Results showed that CLBL is a significant risk factor for LBP (OR: 2.06 (1.32-3.20)). Furthermore, CLBL had a more consistent association with LBP than two of the three risk factors reported earlier. Conclusions From these results it can be concluded that CLBL is a risk factor for the occurrence of LBP, having a more consistent association with LBP compared to most risk factors reported earlier. © 2012 The Author(s)

Interpretable machine learning models for classifying low back pain status using functional physiological variables.

PURPOSE:To evaluate the predictive performance of statistical models which distinguishes different low back pain (LBP) sub-types and healthy controls, using as input predictors the time-varying signals of electromyographic and kinematic variables, collected during low-load lifting. METHODS:Motion capture with electromyography (EMG) assessment was performed on 49 participants [healthy control (con) = 16, remission LBP (rmLBP) = 16, current LBP (LBP) = 17], whilst performing a low-load lifting task, to extract a total of 40 predictors (kinematic and electromyographic variables). Three statistical models were developed using functional data boosting (FDboost), for binary classification of LBP statuses (model 1: con vs. LBP; model 2: con vs. rmLBP; model 3: rmLBP vs. LBP). After removing collinear predictors (i.e. a correlation of > 0.7 with other predictors) and inclusion of the covariate sex, 31 predictors were included for fitting model 1, 31 predictors for model 2, and 32 predictors for model 3. RESULTS:Seven EMG predictors were selected in model 1 (area under the receiver operator curve [AUC] of 90.4%), nine predictors in model 2 (AUC of 91.2%), and seven predictors in model 3 (AUC of 96.7%). The most influential predictor was the biceps femoris muscle (peak [Formula: see text]  = 0.047) in model 1, the deltoid muscle (peak [Formula: see text] =  0.052) in model 2, and the iliocostalis muscle (peak [Formula: see text] =  0.16) in model 3. CONCLUSION:The ability to transform time-varying physiological differences into clinical differences could be used in future prospective prognostic research to identify the dominant movement impairments that drive the increased risk. These slides can be retrieved under Electronic Supplementary Material

Membrane vesicles, current state-of-the-art: emerging role of extracellular vesicles

Release of membrane vesicles, a process conserved in both prokaryotes and eukaryotes, represents an evolutionary link, and suggests essential functions of a dynamic extracellular vesicular compartment (including exosomes, microparticles or microvesicles and apoptotic bodies). Compelling evidence supports the significance of this compartment in a broad range of physiological and pathological processes. However, classification of membrane vesicles, protocols of their isolation and detection, molecular details of vesicular release, clearance and biological functions are still under intense investigation. Here, we give a comprehensive overview of extracellular vesicles. After discussing the technical pitfalls and potential artifacts of the rapidly emerging field, we compare results from meta-analyses of published proteomic studies on membrane vesicles. We also summarize clinical implications of membrane vesicles. Lessons from this compartment challenge current paradigms concerning the mechanisms of intercellular communication and immune regulation. Furthermore, its clinical implementation may open new perspectives in translational medicine both in diagnostics and therapy

Analysis of Exoskeleton Introduction in Industrial Reality: Main Issues and EAWS Risk Assessment

Exoskeletons are part of the technological and organizational innovation sought by the fourth industrial revolution to support and re-launch the manufacturing area. In the present study, we described the experimental protocol designed to test the usability and acceptance of an upper limbs passive exoskeleton. In total, 42 workers from FCA plants volunteered to participate in the research study. The testing campaign included static and dynamic tests aimed at evaluating the potential benefit of the exoskeleton (lessen muscle strain, higher comfort rating and dexterity) vs. possible restrictions to movements and workdevice interactions in tasks resembling work activities. Open questions remain on how to assess the biomechanical workload risk, especially in the design phase, for which holistic methods like EAWS are needed

Palletising Support in Intralogistics: The Effect of a Passive Exoskeleton on Workload and Task Difficulty Considering Handling and Comfort

In logistical processes such as palletising and order picking, musculoskeletal disorders increase. As part of the INNOVATIONSLABOR research project, the latest model of a passive exoskeleton manufactured by LAEVO was investigated in a laboratory study. A final sample of N = 37 persons (73% men) from 20 to 64 years of age evaluated the exoskeleton regarding general comfort, local comfort in different body parts, handling characteristics such as adjustment possibilities, freedom of movement, efficiency, task support and task impairment with validated questionnaires. The analyses show that passive exoskeletons seem to have potential for static activities, but their wearing comfort and user handling should be further developed

Actuation Requirements for Assistive Exoskeletons: Exploiting Knowledge of Task Dynamics

When selecting actuators for assistive exoskeletons, designers face contrasting requirements. Overdimensioned actuators have drawbacks that compromise their effectiveness in the target application (e.g. performance, weight, comfort). In some cases, the requirements on the powered actuator can be relaxed exploiting the contribution of an elastic element acting in mechanical parallel. This contribution considers one such case and describes an approach to fit the actuation requirements closely to the task dynamics, thereby mitigating the drawbacks of overdimensioned actuators

Participatory ergonomic approach for workplace improvements: A case study in an industrial plant

This paper aims to describe the development of an ergonomic program based on the principles of Participatory Ergonomics, in order to implement workplaceimprovements.Acasestudywasconductedinanindustrialplantwhereseveral musculoskeletal disorders were previously identified as being the main cause of a high absenteeism. As a result of the ergonomic intervention program, several different improvements measures were implemented, improving several workplace aspects, namely workers’ posture and, consequently, their working conditions. The obtainedresultsindicatethattherewasasignificantergonomicimprovementintasks where theproposed measureshavebeenimplemented. Theworkers’ satisfactionhas increased considerably after the implementation of the suggested measures. Finally, it was possible to conclude that based in the success of this project, the same approach can also be extended to the remaining company’s workplaces