Mariarosaria Vallone

Manual Assembly Workstation Redesign Based on a New Quantitative Method for Postural Comfort Evaluation

Main purpose of this work is to show how easy and economics an ergonomic/comfort based approach, in re-design a manual assembly workplace, can be; authors, using a new comfort/ergonomic evaluation criterion, analyzed a workstation and identified the critical issues under ergonomic/comfort point of view and finally gave several guidelines to re-design the workplace, implementing minor modification, and improve work-safety, work-quality and productivity. The postural analysis was performed by non-invasive and especially inexpensive methods, based on cameras and video-recorder use and by photogrammetric analysis; DELMIA® DHM software has been used to perform all simulations; comfort analysis was performed by the software developed by researchers of Departments of Industrial Engineering of Salerno: CaMAN®. The test case is an automatic assembly machine that has been modeled and used for virtual postural analysis. Main results of this work can be found in a very good numerical/experimental correlation between acquired/simulated postures and real ones, and on the powerful use of an objective comfort evaluation method, based on biomechanics and posture analysis, for giving to designers the guidelines to re-design a workplace and a work-cycle. This kind of approach seemed to be very powerful in re-designing the work-place and in re-scheduling the work time-sheet because it allowed to improve an ergonomic corrective action with minor costs for company. Obtained results demonstrated the validity of re-design hypotheses through the increase of all comfort indexes and the improvement of workstation/operator productivity.

Ergonomic-driven redesign of existing work cells: the “Oerlikon Friction System” case

The application of ergonomic principles to the design of processes, workplaces and organizations is not only a way to respond to legal requirements but also an indispensable premise for any company seeking to pursue a business logic. This paper shows a cheap and effective method to perform the ergonomic analysis of worker postures in order to optimize productivity and obtain the highest ergonomic ratings. Evaluations were performed for the 5°, 50° and 95° percentiles according to OCRA and NIOSH methods of biomechanical risk assessment. The results highlighted the need for improvements. A virtual simulation using DELMIA® software and the use of workers’ checklists drew attention to problems causing significant physical stress, as identified by ergonomic tools. An ergonomic/comfort-driven redesign of the work cell was carried out, and CaMAN® software was used to conduct a final comfort-based analysis of the worst workstation in the work cell.

Using Axiomatic Design to Identify the Elements That Affect the Evaluation of Comfort/Discomfort Perception

Knowledge about the effects of primary factors on comfort level is useful in Human-Machine-Interface (HMI) design. The study and the mathematical modeling of these effects strongly depends on cross relations between the different kinds of comfort, the primary factors’ effects, and the modifiers’ actions. Starting from a sizeable bibliographic analysis, this paper describes a study, based on the axiomatic design approach, of the interactions between the results, factors, and modifiers in comfort/discomfort evaluation. The modifiers’ influence was determined by measuring the changes in information content. This study allowed us to validate and optimize our equation for the perceived “level of well-being” in order to better study the perception of comfort/discomfort in HMI.

Range of Rest Posture of Human Lower Limbs

The most advocated schemes of comfort perception have proposed an objective method to evaluate “effects in the internal body” and “perceived effects”—the state of the art for comfort/discomfort evaluation. Postural comfort is one aspect of comfort/discomfort perception, and this current work adds to existing knowledge toward a more objectified posture evaluation for comfort. The authors have used the concept of Range of Rest Posture (RRP), as proposed by Apostolico et al. [1], useful for comfort evaluation. The study focused on the identification of RRP within the Comfort Range of Motion (CROM) for these human joints in the lower limbs: hip, knee, and ankle. The proposed method is based on extensive experimental work involving 114 healthy individuals (59 males and 55 females) ranging from 20 to 40 years old. The age range was narrowed to avoid an age-clustering of results due to inhomogeneity of the statistical sample. The experimental data were processed using statistical methods for identifying the RRP in the experimental CROM. Several Maximum Level of Comfort (MLC) positions were found within the RRP. These positions were among the most important information in the comfort evaluation analyses.

The Effect of Wearing Eyeglasses upon Postural Comfort Perception While Using Multi-tasking Electronic Devices in Sitting Position

In this paper, the authors show the results of an anecdotic experiment about the effect the use of eyeglasses has on the body posture of people in seated positions using different kinds of electronic devices: a desktop computer, a laptop, a tablet and a smartphone. The tasks were performed using a fully reconfigurable seating buck on which a standard VDT (Video Display Terminal) workplace with a chair was set. Subjects performed different tasks in order to evaluate the subjective perception of postural comfort. A Digital Human Modeling system was used to model and evaluate, from an ergonomic point of view, the ergonomic level. Software CaMAN®, was used to perform an objective evaluation of the postural comfort of subjects’ upper limbs and to compare the results obtained for the different subjects. The results show that the use of glasses has a significant effect on the body postures of the subjects.