Historical Trend of Work-Related Musculoskeletal Disorders in the Meatpacking and Auto Industries, 1980s-Present.

Occupational Applications This paper provides a historical overview of the rise of Work-Related Musculoskeletal Disorders (WMSDs) in the U.S. from the 1980s to the present, with a special focus on the two industries with the highest recorded rates: Meatpacking and Auto Assembly. The activities underlying this account amount to a major occupational health success story (although still incomplete) in the recognition of these disorders and the development of a nation-wide effort for prevention. An obstacle in creating the data presented here was that the system of recordkeeping changed in multiple ways, making it difficult to compare WMSD rates over time. The work summarized here evaluated the effect of these changes and combined temporal segments that were judged to be the most accurate to create an overall trend line. These results can aid in: 1) showing the overall history of the recognition and prevention of WMSDs, 2) understanding the effects of the recordkeeping changes, and 3) allowing international comparisons of the trends.

An Online Method to Detect and Locate an External Load on the Human Body with Applications in Ergonomics Assessment.

In this work, we propose an online method to detect and approximately locate an external load induced on the body of a person interacting with the environment. The method is based on a torque equilibrium condition on the human sagittal plane, which takes into account a reduced-complexity model of the whole-body centre of pressure (CoP) along with the measured one, and the vertical component of the ground reaction forces (vGRFs). The latter is combined with a statistical analysis approach to improve the localisation accuracy, (which is subject to uncertainties) to the extent of the industrial applications we target. The proposed technique eliminates the assumption of known contact position of an external load on the human limbs, allowing a more flexible online body-state tracking. The accuracy of the proposed method is first evaluated via a simulation study in which various contact points on different body postures are considered. Next, experiments on human subjects with three different contact locations applied to the human body are presented, revealing the validity of the proposed methodology. Lastly, its benefit in the estimation of human dynamic states is demonstrated. These results add another layer to the online human ergonomics assessment framework developed in our laboratory, extending it to more realistic and varying interaction conditions.

Ergonomics assessment methods used by ergonomics professionals.

A web-based survey was conducted of ergonomics practitioners holding certifications in the U.S., Canada, Great Britain, Australia, and New Zealand. The survey follows 12 years after an earlier initial survey reported by Dempsey et al. (2005). Approximately 1221 eligible participants were invited by e-mail to participate, and 405 surveys were included in the final analysis. The survey queried use of basic instruments relevant to ergonomic practice as well as more specific analytical tools such as observational techniques for assessing postural demands of work and instrumentation for direct measurement of such demands. Some ergonomic assessment methods appear to have increased in their overall use by U.S. ergonomists compared to 2005 data. This was observed for: RULA, REBA, Psychophysical Upper Extremity Data, Strain Index, and ACGIH TLV for Hand Activity Level. There is minimal evidence of increased overall use of direct measurement approaches in the U.S. There appear to be geographic differences between countries/continents in terms of use of various methods. The use of mobile device/smart phone "apps" by ergonomists was queried and these technologies presently appear to be in early adoption phase with 24-28% of practitioners reporting use of an app in their ergonomics practice.

Evaluation of a virtual reality head mounted display as a tool for posture assessment in digital human modelling software.

The purpose of this work was to assess the feasibility of using a head mounted display with a motion capture system to simulate real world occupational tasks. Participants performed a pointing task under 3 conditions: (1) real environment (REA), (2) virtual environment with auditory stimulus (VEA) and (3) virtual environment with visual stimulus (VEV). End point error, movement time and peak fingertip velocity were calculated for each discrete point event. Upper extremity joint angles were calculated at the end-state for each point and did not significantly differ between real and virtual conditions. There was significantly greater target error in virtual conditions, compared to the real condition. Peak pointing velocity was slower and movement time was longer during virtual conditions. The similarity of joint angles between real and virtual conditions suggests future use of posture-based ergonomic assessments for use with virtual reality task simulations using Oculus Rift and Siemens Jack.

Wearable Monitoring Devices for Biomechanical Risk Assessment at Work: Current Status and Future Challenges-A Systematic Review.

Background: In order to reduce the risk of work-related musculoskeletal disorders (WMSDs) several methods have been developed, accepted by the international literature and used in the workplace. The purpose of this systematic review was to describe recent implementations of wearable sensors for quantitative instrumental-based biomechanical risk assessments in prevention of WMSDs. Methods: Articles written until 7 May 2018 were selected from PubMed, Scopus, Google Scholar and Web of Science using specific keywords. Results: Instrumental approaches based on inertial measurement units and sEMG sensors have been used for direct evaluations to classify lifting tasks into low and high risk categories. Wearable sensors have also been used for direct instrumental evaluations in handling of low loads at high frequency activities by using the local myoelectric manifestation of muscle fatigue estimation. In the field of the rating of standard methods, on-body wireless sensors network-based approaches for real-time ergonomic assessment in industrial manufacturing have been proposed. Conclusions: Few studies foresee the use of wearable technologies for biomechanical risk assessment although the requirement to obtain increasingly quantitative evaluations, the recent miniaturization process and the need to follow a constantly evolving manual handling scenario is prompting their use.

Initial experience using a robotic-driven laparoscopic needle holder with ergonomic handle: assessment of surgeons' task performance and ergonomics.

PURPOSE: The objective of this study is to assess the surgeons' performance and ergonomics during the use of a robotic-driven needle holder in laparoscopic suturing tasks. METHODS: Six right-handed laparoscopic surgeons with different levels of experience took part in this study. Participants performed a set of three different intracorporeal suturing tasks organized in ten trials during a period of five weeks. Surgeons used both conventional (Conv) and robotic (Rob) laparoscopic needle holders. Precision using the surgical needle, quality of the intracorporeal suturing performance, execution time and leakage pressure for the urethrovesical anastomosis, as well as the ergonomics of the surgeon's hand posture, were analyzed during the first, fifth and last trials. RESULTS: No statistically significant differences in precision and quality of suturing performance were obtained between both groups of instruments. Surgeons required more time using the robotic instrument than using the conventional needle holder to perform the urethrovesical anastomosis, but execution time was significantly reduced after training ([Formula: see text] 0.05). There were no differences in leakage pressure for the anastomoses carried out by both instruments. After training, novice surgeons significantly improved the ergonomics of the wrist ([Formula: see text] 0.05) and index finger (Conv: 36.381[Formula: see text], Rob: 30.389[Formula: see text]; p = 0.024) when using the robotic instrument compared to the conventional needle holder. CONCLUSIONS: Results have shown that, although both instruments offer similar technical performance, the robotic-driven instrument results in better ergonomics for the surgeon's hand posture compared to the use of a conventional laparoscopic needle holder in intracorporeal suturing.

Height-Adjustable Desks: Energy Expenditure, Liking, and Preference of Sitting and Standing.

BACKGROUND: Breaking periods of sitting with standing may prevent chronic diseases and increase energy expenditure (EE). Sit-to-stand height adjustable desks may promote workplace standing, but workers have to be willing to stand for portions of the workday. METHODS: For studies 1 and 2, EE was measured during word processing while sitting in a chair and while standing. Subjects scored their liking of each posture and time they would be willing to work in each posture during an 8-hour workday. Study 2 included an intervention of replacing subjects' sitting desks with a height adjustable desk. Liking of and willingness to work in each posture were measured before and after the 12-month intervention. RESULTS: EE was 7.5 kcal/h greater when standing than when sitting. Subjects liked sitting more than standing in study 1. In study 2, liking of postures did not differ or change across 12 months use of height adjustable desks. Perceived willingness to stand decreased from 4.5 h/d at baseline to 3.4 h/d after 12 months. CONCLUSIONS: Standing rather than sitting increased EE by 7.5 kcal/h. Use of a height adjustable desk for 12 months did not alter the hedonic value of standing or sitting, which is promising for long-term increases in standing.

[Ease of handling of first and second generation rebound tonometers]. / Handhabung von Reboundselbsttonometern der ersten und zweiten Generation.

PURPOSE: To evaluate the ease of handling of two rebound tonometers, which are designed for self-measurement of intraocular pressure (IOP) in a clinical setting by untrained patients. METHODS: After self-measurement of the IOP with the rebound tonometers iCare ONE and iCare HOME, participants were asked to complete a questionnaire containing different subitems concerning ease of operation using a visual analog scale (1 = very good to 5 = very poor). Moreover, the feasibility and duration of measurement were tested. RESULTS: A total of 147 subjects participated in this study. The mean score for general handling ability was 2.79 ± 1.01 for the iCare ONE and 1.85 ± 0.87 for the iCare HOME (p < 0.001). The evaluation of the subitems sense of safety (iCare ONE: 2.71 ± 1.03 and iCare HOME: 1.87 ± 0.81, p < 0.001) and comfort of measurement (iCare ONE: 2.07 ± 1.01 and iCare HOME: 1.66 ± 0.72, p < 0.001) also showed a significant discrepancy between the two tonometers. Participants needed significantly less time for a single valid measurement when using the iCare HOME tonometer (mean 66.14 ± 61.54 s) compared to the iCare ONE tonometer (mean 81.54 ± 69.51 s, p < 0.001). CONCLUSIONS: A better handling of the iCare HOME rebound tonometer in comparison to the iCare ONE tonometer can be deduced on the basis of the subjective assessments of patients and the shorter duration of measurements. Moreover, the iCare HOME received a significantly better evaluation for all subitems. The accuracy of measurements using the iCare HOME still needs to be clarified.

EEG-based usability assessment of 3D shutter glasses.

OBJECTIVE: Neurotechnology can contribute to the usability assessment of products by providing objective measures of neural workload and can uncover usability impediments that are not consciously perceived by test persons. In this study, the neural processing effort imposed on the viewer of 3D television by shutter glasses was quantified as a function of shutter frequency. In particular, we sought to determine the critical shutter frequency at which the 'neural flicker' vanishes, such that visual fatigue due to this additional neural effort can be prevented by increasing the frequency of the system. APPROACH: Twenty-three participants viewed an image through 3D shutter glasses, while multichannel electroencephalogram (EEG) was recorded. In total ten shutter frequencies were employed, selected individually for each participant to cover the range below, at and above the threshold of flicker perception. The source of the neural flicker correlate was extracted using independent component analysis and the flicker impact on the visual cortex was quantified by decoding the state of the shutter from the EEG. MAIN RESULT: Effects of the shutter glasses were traced in the EEG up to around 67 Hz-about 20 Hz over the flicker perception threshold-and vanished at the subsequent frequency level of 77 Hz. SIGNIFICANCE: The impact of the shutter glasses on the visual cortex can be detected by neurotechnology even when a flicker is not reported by the participants. Potential impact. Increasing the shutter frequency from the usual 50 Hz or 60 Hz to 77 Hz reduces the risk of visual fatigue and thus improves shutter-glass-based 3D usability.

Comparison between low-cost marker-less and high-end marker-based motion capture systems for the computer-aided assessment of working ergonomics.

The paper deals with the comparison between a high-end marker-based acquisition system and a low-cost marker-less methodology for the assessment of the human posture during working tasks. The low-cost methodology is based on the use of a single Microsoft Kinect V1 device. The high-end acquisition system is the BTS SMART that requires the use of reflective markers to be placed on the subject's body. Three practical working activities involving object lifting and displacement have been investigated. The operational risk has been evaluated according to the lifting equation proposed by the American National Institute for Occupational Safety and Health. The results of the study show that the risk multipliers computed from the two acquisition methodologies are very close for all the analysed activities. In agreement to this outcome, the marker-less methodology based on the Microsoft Kinect V1 device seems very promising to promote the dissemination of computer-aided assessment of ergonomics while maintaining good accuracy and affordable costs. PRACTITIONER'S SUMMARY: The study is motivated by the increasing interest for on-site working ergonomics assessment. We compared a low-cost marker-less methodology with a high-end marker-based system. We tested them on three different working tasks, assessing the working risk of lifting loads. The two methodologies showed comparable precision in all the investigations.

Assessment of Mental, Emotional and Physical Stress through Analysis of Physiological Signals Using Smartphones.

Determining the stress level of a subject in real time could be of special interest in certain professional activities to allow the monitoring of soldiers, pilots, emergency personnel and other professionals responsible for human lives. Assessment of current mental fitness for executing a task at hand might avoid unnecessary risks. To obtain this knowledge, two physiological measurements were recorded in this work using customized non-invasive wearable instrumentation that measures electrocardiogram (ECG) and thoracic electrical bioimpedance (TEB) signals. The relevant information from each measurement is extracted via evaluation of a reduced set of selected features. These features are primarily obtained from filtered and processed versions of the raw time measurements with calculations of certain statistical and descriptive parameters. Selection of the reduced set of features was performed using genetic algorithms, thus constraining the computational cost of the real-time implementation. Different classification approaches have been studied, but neural networks were chosen for this investigation because they represent a good tradeoff between the intelligence of the solution and computational complexity. Three different application scenarios were considered. In the first scenario, the proposed system is capable of distinguishing among different types of activity with a 21.2% probability error, for activities coded as neutral, emotional, mental and physical. In the second scenario, the proposed solution distinguishes among the three different emotional states of neutral, sadness and disgust, with a probability error of 4.8%. In the third scenario, the system is able to distinguish between low mental load and mental overload with a probability error of 32.3%. The computational cost was calculated, and the solution was implemented in commercially available Android-based smartphones. The results indicate that execution of such a monitoring solution is negligible compared to the nominal computational load of current smartphones.

Endoscopic Valves and Irrigation Devices for Flexible Ureteroscopy: Is There a Difference?

BACKGROUND AND PURPOSE: A variety of ureteroscopic irrigation systems are available, ranging from gravity-driven pressure bags to hand-operated pumps. Endoscopic valves maintain a watertight seal during ureteroscopy (URS) while facilitating passage of instruments. The clinical utility and ergonomics of such devices have not been established. We systematically compare the mechanical properties and usability of select valve devices and hand-operated irrigation systems in an in vitro setting. MATERIALS AND METHODS: In vitro testing of four different endoscopic valves: UroSeal adjustable endoscopic valve (US Urology), adjustable biopsy port seal (Gyrus ACMI), Blue Silicone Seal ACMI CS B612 (Gyrus ACMI), and REF ABP Biopsy Port Seal (ACMI Corporation) was performed. Usability was evaluated via insertion/extraction forces and insertion time for instruments, including a straight tip sensor wire, 0.035″, (Boston Scientific), a laser fiber (Flexiva 200, Boston Scientific), and an Ngage Nitinol Stone Extractor 1.7F (Cook Urological) through a flexible ureteroscope (Olympus URF P5, Olympus). Flow rate, flow time, and user fatigue were tested for two irrigation systems: The single action pumping system (SAP, Boston Scientific) and the Pathfinder Plus (PP, Utah Medical Products). RESULTS: The US needed the shortest time for both wire insertion and basket insertion (P=0.005, and P<0.001, respectively), while the BSS needed the greatest time for laser fiber insertion (P<0.005). The REF ABP needed the greatest force for withdrawal of the Ngage basket, the laser fiber, and the Captura stone grasper through a closed seal, while the US took the least amount of force for both laser fiber withdrawal and insertion via analysis of variance. Leak point pressure assessment demonstrated that the US was leak free at irrigation pressures up to 200 mm Hg, while the ABP, BSS, and the REF ABP devices demonstrated leaks ranging from 30 to 200 mm Hg. The average and peak flow of the SAP were significantly higher than that of the PP. Mean grip strength decreased significantly after operation of the SAP for 10 minutes, while no loss of grip strength was observed after use of the PP. CONCLUSIONS: The US valve has the advantage of facile manipulation of wires and baskets while maintaining a watertight seal, while other devices may be more cost-effective and secure. The PP has the advantage of less operator hand fatigue and ease of use, but the SAPS may allow for greater on-demand pressures. Further studies are needed to evaluate the effect of these irrigation systems on outcomes.

The Minimally Invasive Manipulator: an ergonomic and economic non-robotic alternative for endoscopy?

INTRODUCTION: Since the da Vinci robotic system was introduced, it has been reported to have ergonomic advantages over conventional laparoscopy (COV). High investments associated with this system challenged us to design a more economical, mechanical alternative for improvement of laparoscopic ergonomics: the Minimally Invasive Manipulator (MIM). MATERIAL AND METHODS: An earlier reported MIM prototype was investigated. Its shortcomings were input for the establishment of design criteria for a new prototype. RESULTS: A new prototype was developed, aiming at improved intuitiveness and ergonomics. The handle and instrument tip were redesigned and the parallelogram mechanism was converted from linear moving parts to mainly rotating parts. DISCUSSION: The new prototype was tested by a panel of experts and novices during an indicative ergonomic experiment. A major advantage of the MIM seems to be the possibility to perform laparoscopic surgery in a sitting position, in line with the working axis, instead of standing at the side of the patient. At an estimated cost level of 10% of the da Vinci system, the MIM can be an economical alternative for the enhancement of laparoscopy ergonomics. However, further development for clinical feasibility is necessary.

Toward more usable electronic voting: testing the usability of a smartphone voting system.

OBJECTIVE: The goal of this research was to assess the usability of a voting system designed for smart-phones. BACKGROUND: Smartphones offer remote participation in elections through the use of pervasive technology. Voting on these devices could, among other benefits, increase voter participation while allowing voters to use familiar technology. However, the usability of these systems has not been assessed. METHOD: A mobile voting system optimized for use on a smartphone was designed and tested against traditional voting platforms for usability. RESULTS: There were no reliable differences between the smartphone-based system and other voting methods in efficiency and perceived usability. More important, though, smartphone owners committed fewer errors on the mobile voting system than on the traditional voting systems. CONCLUSION: Even with the known limitations of small mobile platforms in both displays and controls, a carefully designed system can provide a usable voting method. Much of the concern about mobile voting is in the area of security; therefore, although these results are promising, security concerns and usability issues arising from mitigating them must be strongly considered. APPLICATION: The results of this experiment may help to inform current and future election and public policy officials about the benefits of allowing voters to vote with familiar hardware.

Matching work capacities and demands at job placement in employees with disabilities.

OBJECTIVE: To determine whether employees with disabilities were initially assigned to jobs with work demands that matched their work capacities. PARTICIPANTS: Forty-six employees with various physical, mental, sensory and multiple disabilities working in a sheltered workshop. METHODS: Physical and psychosocial work capacities were assessed post-offer and pre-placement using the Ergo-Kit and Melba. Work demands of the jobs were determined by workplace assessments with TRAC and Melba and were compared with the work capacities. RESULTS: Of the 46 employees, 25 employees were not physically overloaded. When physical overload occurred, it was most often due to regular lifting. All employees were physically underloaded on six or more work activities, most often due to finger dexterity and manipulation. Almost all employees (n=43) showed psychosocial overload or underload on one or more psychosocial characteristics. Psychosocial overload was most often due to endurance (long-term work performance), while psychosocial underload was most often due to speaking and writing. CONCLUSION: Despite the assessment of work capacities at job placement, underload and overload occurred on both physical activities and psychosocial characteristics. Assessing both work capacities and work demands before job placement is recommended. At job placement more attention should be paid to overloading due to lifting and long-term work performance.

Development of an ergonomics device for maintenance of hydraulic generators of Tucuruí hydropower plant.

This paper aims to present an ergonomic device to assist in the maintenance of the units of Tucuruí Hydropower Plant. The development of this ergonomic device made possible to reduce maintenance time, reduce losses caused by billing, improve performance and reduce the physical strain for labors during the execution of services.

Novel method for quantitative assessment of physical workload of healthcare workers by a tetherless ergonomics workstation.

Healthcare workers are at risk of physical injury. Our laboratory has developed a tetherless ergonomics workstation that is suitable for studying physicians' and nurses' physical workloads in clinical settings. The workstation uses wearable sensors to record multiple channels of body orientation and muscle activity and wirelessly transmits them to a base station laptop computer for display, storage, and analysis. The ergonomics workstation generates long records of multi-channel data, so it is desired that the workstation automatically process these records and provide graphical and quantitative summaries of the physical workloads experienced by the healthcare workers. This paper describes a novel method of automated quantitative assessment of physical workload, termed joint cumulative amplitude-duration (JCAD) analysis, that has advantages over previous methods and illustrates its use in a comparison of the physical workloads of robotically-assisted surgery versus manual video-endoscopic surgery.