Preventing Work-Related Musculoskeletal Disorders in Manufacturing by Digital Human Modeling

Simulation analysis of low back forces in Snatch and Clean & Jerk movements via digital human modelling

BACKGROUND

Weightlifting is an Olympic sport for dynamic strength and power, and requires the execution of different lifting techniques It is important to analyze the forces subjected to the lower back during weightlifting movements to prevent injuries. Digital Human Modeling (DHM) is a powerful tool that can be used to analyze and optimize the performance of humans while doing their work or activities.

OBJECTIVE

The purpose of this study is to present a simulation analysis of the lower back forces during the execution of two weightlifting techniques: Snatch (SN) and Clean & Jerk (CJ), with different loads and for both genders.

METHODS

Digital Human modelling through JACK simulation package was used analyze the forces exerted on the lumbosacral area (L5-S1) of the lower back in order to determine the risk for low back injuries. The level of compression and shear forces recommended by the literature have been set as thresholds. The simulaitons were performed in male and female models, with loads from 20-100 kg.

RESULTS

The results show that any weight higher than 60 kg in both movements poses risk for the weightlifters in terms of compression and shear forces. It has been observed that weightlifters can lift greater loads in the CJ technique compared to the SN technique. Furthermore, females are able to lift higher loads with lower risk of injuries.

CONCLUSION

Weightlifting is a high-risk activity due to the high levels of shear and compression forces that the body is exposed to during the lifting techniques. Digital Human Modeling holds significant value due to their ability to facilitate the exploration of diverse conditions within a safe environment, devoid of any potential harm to human subjects.

Development of a New Procedure for Evaluating Working Postures: An Application in a Manufacturing Company

Musculoskeletal diseases represent a constant phenomenon in occupational health and safety (OHS) despite the large effort at governmental and technical levels. In the industrial context, numerous studies have dealt with the evaluation of the physical demand of workers. Moreover, numerous studies have investigated the problem, providing tools for ergonomics analysis. However, practical approaches aimed at integrating ergonomics issues in risk assessment activities are still scarce. To reduce such a gap, the current study proposes a procedure for the evaluation of the static working postures of workers to be included in the risk assessment activities. Such an approach is based on the ISO 11226 standard, providing a practical checklist that can be used both at the workstation's design stage and during risk assessment activities. Its effectiveness was verified through a case study at a manufacturing company. The results achieved showed that as well as the non-conformity of the workstations' design, the lack of training of the operators on how to maintain a neutral posture while working can also lead to awkward postures of the trunk and head. Additionally, the proposed methodology allowed us to verify the correctness of each workstation based on the physical characteristics of the workers, providing a useful guideline for the company managers on how to properly assign working tasks.

Analysis of Healthcare Push and Pull Task via JACK: Predicted Joint Accuracy during Full-Body Simulation

The posture accuracy of full-body dynamic simulation has been successfully evaluated in JACK Siemens software via analyzing two common push and pull tasks. The difference in joint angles between the actual and predicted human movement directly results in the strength of force exposed on the lumbar spine. In this study, the individual factors, such as body height, body weight, trunk and hip flexion, shoulder movement, and muscle strength between genders, have shown a strong association with the adopted postures and exposed spinal forces during task performance. To provide robust ergonomics analysis, these individual variables should be adequately considered in software design for the long-term goal of injury prevention in diverse occupational workplaces.

Ergonomics evaluation of lawn mower operator’s working posture using JACK software and kinect interface

BACKGROUND: Nowadays, real-time motion tracking devices are widely used for ergonomic assessment of several manual quotidian activities. The real-time tracking of human activities makes it easier to observe the exposure of work-related musculoskeletal disorders (WMSDs) in the human body. OBJECTIVE: This study aims to determine the suitability of a real-time motion tracking device (Kinect v1 interfaced with a commercial ergonomic assessment software, JACK) for real-time ergonomic evaluation of the strenuous operation of the manual lawn mower. METHOD: The lawn mower operators perform various strenuous activities while operating the manual lawn mower for long intervals of time, which causes WMSDs in the entire body of the operators. These working operators’ activities have been captured using Kinect v1 interfaced with JACK, to address the ergonomic issues responsible for the whole-body WMSDs. The forces acting on the lower back, Rapid Upper Limb Assessment score and static strength have been predicted using JACK. RESULTS: This study proves the exposure of the operators towards the whole-body WMSDs while operating the manual lawn mower. CONCLUSION: The findings provide a quick and straightforward approach for performing the real-time ergonomic evaluation of any operation, which can help the industrial staff estimate the risk of level WMSDs.

Ergonomic Rationalization Sequence of Digital Lighting Design in the Working Environment

This paper describes the creation of a rationalization sequence for working with simulation models, and its subsequent verification in the redesigning of lighting in cooperation with digital enterprise tools. The rationalization sequence consists of 11 sequences, whose accuracy is subsequently verified on a practical example of the redesign of an assembly room of a production hall in the simulation tool Dialux Evo. In conjunction with the proposed procedure, a redesign of the assembly workplace located in the production hall for daylighting, artificial, and mixed lighting was created. The conclusion of the paper provides an overview of the benefits gained from the application of the work environment rationalization procedure.