Digital Human Modeling and Simulation for Ergonomics Workspace

D. Braatz, Digital Human Modeling and Simulation for Ergonomics Workspace Design

Digital Human Modeling and Simulation for Ergonomics Workspace Design: two Brazilian cases D. BRAATZ*†, L.TONIN†, A. FONTES‡ and N. MENEGON† † Department of Production Engineering (Federal University of São Carlos), São Carlos, Brazil ‡Department of Production Engineering – Campus Sorocaba (Federal University of São Carlos), Sorocaba, Brazil

Abstract In Brazil the technology of Digital Human Modeling and Simulation (DHMS) on workspace design is still at the initial phase of diffusion. On this context this paper investigates a computational tool for Digital Human Modeling and Simulation contextualized by Ergonomics Analysis of Work (EAW) and the analysis of the likely future activities can assist in the design processes of workplaces. The aim of this study is to show how Digital Human Modeling and Simulation and contextualized by Ergonomics can help on the process of workplace design and which of the theoretical references used as support. Two case studies in which the DHMS was employed with the software Jack are examined. The first case presents the design of an attendance counter in a public postal service. The second shows the development of a workstation for the supply of surgical needles in a company manufacturing products of health and hygiene. From the results of case studies are explained the contributions and challenges of using this technology in design aiming to solve the issues of health and productivity. The results presented show that using this technology on a structured and conceptually based way, can be considered an auxiliary instrument on the search of consideration of the possible future activity (Future Activity Approach) and identifying possible constraints on projects of productive situations. On the other hand, such tool is proper from human factors, of a highly technicality matter, with emphasis on biomechanical factors, anthropometric and with big focus on quantitative analyses. The use of integrated DHMS with ergonomics intervention helped improve anticipation of likely future activities of new situations of work and helped the integration and communication of the actors involved in the social process. Keywords: Digital Human Simulation; Workplace Design; Activity-centered Ergonomics, Action Research.

1. Introduction In Brazil the technology DHM is still at the initial phase of diffusion. Only a few companies and institutions adopt this structured tool, being common the acquisition of the software license and further use at specific and isolated cases. Schaefers et al. (2011) presents some reasons for the low use of DHM on the part of designers, including the lack of this technology and few anthropometric data updated. In Brazil the most recent anthropometric survey, with data collected and published based on the needs of a DHM software date 2002. Others limitations concerning the use of DHM have been identified (Magistris et al. 2013), for example biomechanical approximations, static calculation, description of the probable future situation or statistical data on human performance characteristics. The incorporation of perspective of the activity throughout the method of analysis of work is a

*Corresponding author. Email: [email protected]

difference presented in this study and it correlates the main lines of ergonomics and its instruments. Considerations are also made on the limits of the use of these technologies, and the big demand for efficient methods and capable users to operate them. The aim of this study is to show how DHMS can help on the process of workplace design and the theoretical references used as support.

2. Theoretical aspects The use of simulation on the process of engineering projects, during an ergonomic study, must be based on concept and methodology in order to obtain effective results (Daniellou, 2002a).On this context, it was suggested a participative approach in order to allow discussion and to build up consensus, deals and deliberations on the project. Therefore, action search goals were articulated about the reality through confrontations of different world-objects

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D. Braatz, Digital Human Modeling and Simulation for Ergonomics Workspace Design

(Bucciarelli, 1994). Such comprehension demands mechanisms that allow the integration of different actors involved in the project (employees of different workplaces, managers, researchers, among others) to build a collective of the problem and of the field of possible solutions, emanating from the reality of the situation and considering its various interpretations, providing propitious environment for the decision-making and validating (Menegon, 2003). To Daniellou (1995), the elements of technical rationality (based on the theory of systems and problem solving) and the model of negotiation of constraints (which considers that the project activity has an unstructured character and that the technical artifacts are socially built) can be worked together. The practice of ergonomics must not only describe the processes of conception, but also influence them in favor of the conception of an effective working situation (related to the productive action efficiency) and compatible with the health of workers.

3. Methodology The main aid of DHMS on workplace design is related here in two distinct situations: the first one inserted in an ergonomics project, on which was used the Ergonomics Analysis of Work (EAW). The second situation brings the result of a perennial problem of survey and analysis of ergonomics risks, through the use of the Ergo Job Analyzer, this instrument, according to Bertoncello (2004), was developed to evaluate workstations from body posture analysis, frequency of movements in similar or distinct activities, load spent, among other factors. It considers not only the movement of each body articulation in each activity, but it requests to number movements as in a total account per day. The EJA “indicates different amplitude of movements (…) so, the movements of each body segment are added according to their own specific amplitude, in each shift, also respecting the biarticular (right and left shoulders individually added, for example), when there is” (Bertoncello, 2004). The result presented by EJA is the quantification of the risk associated to the workstations. This is characteristic of the American philosophy of Ergonomics, Human Factors, which focuses on the comprehension of the nature of the interaction between men and artifact, including a variety of products, processes and environments. The computational tool of Digital Human Modeling and Simulation used in this research has also a bigger influence of the Human Factors, the extent that it shows the man-workplace relationship in a quantitative way, emphasizing its considerations on physical aspects and attributing a lower relevance to organizational and cognitive aspects of the future activity.

To Ziolek and Kruithof (2000), the DHMS process can be divided in three large groups: the environment (including CAD – computer aided design – drawings), manikins (or digital human models built on anthropometric data) and the analysis (possible to be made from simulation). Considering the division proposed by Ziolek and Kruithof (2000) it can be characterized that the environment is not only the result of drawings and geometric data, but also of the activity developed by workers (in contrast to the task given by the organization). The activity also influences DHMS in relation to the actions and postures that the dummies (manikins) perform at their workstations. 3.1. Analysis of activity The analysis of activity allows the project to contemplate the real task to be performed at the future workstation. For this, is used an analysis of reference situations, characterization of these activities and the effective participation, during the project, of workers with diverse skills similar to the future operators (Daniellou, 2002b). Thus, besides the tasks prescribed by the organization, there is an incorporation in modeling of the task, productivity and health. That is, the simulation must consider the operative modi operandi, understood here as the commitment of the operator to the task, production goals, results obtained and the internal state of the worker (Daniellou, 2005). However, such incorporation is considered to be limited by the software which cannot comprehend the cognitive dimensions of the work in its interface. 3.2. Digital Human Modeling and Anthropometry The process of Digital Human Modeling is decisive to the simulation efficiency, especially in the context of the case studies following presented, in which it is used as a project tool (towards the anthropometric necessities anticipation) and as an intermediate object to participation in construction and validation of the evolutionary scenarios. In order to validate the simulation results it is needed to consider modeling able and trustworthy. It is of great importance that the anthropometric data are adherent to the morphological characteristics of the workplace users under analysis and project. Accordingly Brazil faces the same difficulty faced by most countries which operate with human modeling, i.e., the lack of discerning and updated anthropometric data, except for some countries, for example Germany (SIZEGERMANY, 2010). On the other hand, the Brazilian context of scarcity has been attenuated after an anthropometric research conducted in 2001 in an airline from São Paulo state (Menegon et al., 2002). Such research has a great differential on the definition of the variables, respecting that the

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segments and proportions were defined according to the interface of data entrance of the software used. From the data it is possible to build human digital models, being that software Jack considers 24 anthropometric variables and the sex of the manikin. 3.3. DHMS and Analysis On the perspective of this research the aims of DHMS is to support the process of design, as an intermediate object, as to anticipate future possible constraints. The intermediation of the different agents during this process can be helped by DHMS as it facilitates the comprehension of the different details of the project, allowing its visualization on threedimensional representation, anticipating its possible uses and applications even though in digital environment. Besides this tool, this stage uses sketches, CAD drawings with plans and perspectives, physical models in scale and mock-up (model in regular size), moreover a descriptive memorial about the characteristics of the project and its future applications, among other resources. The new technologies of computer graphics and engineering software, on the other hand, will not make such instruments unnecessary, but it will be complementary to them. 3.4. Characterization of the software used Software Jack is a computer graphic tool which allows simulations of real work situations, aiming at the environment and, mainly, the human figure. Anticipating ergonomic and usage questions, the design process becomes faster, safer and with a greater chance of being successful. The physical prototyping stage can hardly ever be discarded, although, its costs and demanding time can be considerably reduced using this stage to verification and validation of other details, since that part of the problems that would have been found had already been identified and solved during digital prototyping. After the simulation it is possible to continue to the analysis stage. The main analysis derived from the software is the biomechanical analysis. Through observation and analysis of workplaces, it is possible to identify postures and movements (considering time and repetition) that offer risk of damage to the workers’ health. At Jack, these tools of analysis are based by different studies, allowing each analysis to be done faster and more precisely by worker-environment relationship, and allowing some data to be obtained automatically. The analysis performed by the software allow reports to be made under quantitative information and comparative studies of situations with different

characteristics (organization variability) considering the diversity of the population in the environment analyzed (anthropometric variability of subject). Choosing this specific software, not a similar one, is due to a partnership between UFSCar and UGS Siemens.

4. Case studies The cases used in this paper come from projects of the author’s research group at UFSCar. Both are workplaces, the first one at a company in the postal service sector and the second one at a manufacturing company. The software version used in both projects was the Jack 2.2i, classic (Classic Jack), and the environments were designed in AutoCAD (Autodesk) and then imported by Jack. 4.1. Case Study 1: Design of an attendance counter The company (Case 1) can be defined as one of the biggest Brazilian public companies, especially by its diffusion throughout the country and by the huge number of employees. The request for ergonomic intervention in this company, as showed by Fontes et al. (2006), came as an answer to the various numbers of lawsuits referring to the compliance with safety and medical standards of the Brazilian labor laws. The demands brought up by the company were: furniture inadequacy, the introduction of new computerized systems, of electronic monitoring of work and the organization of work in general (Fontes et al., 2006). Analyzing the medical certificates sent two bigger fields of problems were found: musculoskeletal diseases and mental disorders. The complaints related to physical constraints were fundamentally attached to the worker postures, because of the limitations imposed by the furniture. In relation to mental disorders, these were related to the attention demanded (cognitive load) and responsibility (psychological load). The ergonomic intervention was constituted by the following stages:  

 

Analysis of the necessity and context (understanding the context and eliciting the problems to be solved); Analysis of the task (understanding which task should be done by workers and the environmental, technical and organizational conditions of this practice. It is essential to know how the task is prescribed inside the organization); Analysis of the activity (understanding what workers effectively do to obtain the expected results in each task); Diagnose the present situation;

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D. Braatz, Digital Human Modeling and Simulation for Ergonomics Workspace Design  

Develop project concepts; Hierarchization of solutions, restrictions of adaptability andinteraction with users of the workstation;  Furniture design;  Digital Human Modeling and Simulation;  Implementation of improvements;  Technical specifications;  Building up of the physical prototype and implantation;  Validation (confronting the implanted object and its interaction with the user) with evaluations, applying questionnaires of perception with users and modifications;  Guide for practice (in order to make workers aware of the improvements implemented in the workstations and with usage elucidation). The conceptual proposal of a new counter was brought up after an analysis on the activity taken by users, diagnosis and results from the biomechanical analysis for each model of counter available nowadays. The project has been through some discussions and refinement with the group of work until the manufacturing of prototypes. The project requirements for the design of the new counter were discussed considering the characteristics aimed, and were selected under the following categories of analysis: A great number of simulations and analyses were made with software Jack pointing the favorable geometry to fulfill the requirements wished in agreement with the workers well-being. In all simulations and analysis were used a male manikin percentile 95, as a subject of extreme maximum limit, and a female manikin percentile 05, as the minimum limit. Thus, the aims were to project a workstation able to fit most part of the population under study. The following presents as the technology of human modeling and simulation contributing for each analysis category. On the characterization of risk factors of the task video recordings of the working process were made. There were identified 13 categories of products and, in them, 23 distinct processes. During the analysis it was noticed that the task of client attendance could be divided into stages according to predominance of them in all activities done by the attendant. So, the positioning of each body segment was verified during the following fragmented stages: picking up/delivery of material from the client; reading/writing on postal object; stamping; picking up empty boxes; storing the postal object in the specific box; typing; cash operation; organizing documents; and, organizing products. The workstation studied consists especially of an attendance counter where the technical devices are put on. These can be categorized as furniture (attendance counter), gadgets (an authenticator

machine, a big scale, a small scale, a Pin keyboard, “SARA” equipment, a bar code reader of bank checks, a bar code reader for labels, a monitor, a mouse, a keyboard and a CPU) and office supplies (a stamp pad, a calculator, stamps, tape or packaging tape dispenser, stapler, a coin compartment, a postal stamp pad or rubber, and folder).

Figure 1: Perspectives of the present attendance counter (left) and the new one (right) (Fontes et al. 2006)

The adoption of the “U” shape for the top counter (in contrast to the present “L” shape) is to fulfill the demand of space, that, in consonance to the liberation of the lower part of the counter, removing the drawing from the present counters, allowing the attendant to spin 180 degrees in diverse possibilities of regulation in order to choose the best operating way wished, apart from contemplating both right and left handed users. Through simulations of the probable future activity it was possible to observe and evaluate questions like the relation of profundity of the countertop and the attendance reach, especially regarding the female digital manikin percentile 05 and its interaction with customers and objects. Another important contribution of Digital Human Modeling and Simulation in this category of analysis was the verification of the disposable of the great number of equipments used and the impact in the available space. With the help of the work group and users of the station who know the daily routine of this task, it was possible to establish a possible configuration of how the workstation could be organized. However, it is necessary to reinforce the importance of allowing workers to organize their workstation according to their own modus operandi, increasing this way the regulation space. It stands out that from the “U” workstation surface other parameters were influenced like the necessity of adopting a swivel chair and with sliding wheels to allow rotation and easy stand out of the station. Therein, composing a new workstation, within the counter, the chair was one of the main items evaluated, because it impacts straight in a series of other aspects, like the perception of comfort of the user, height of working surface, support for inferior and superior limbs, customer/attendant relationship, personal safety of the attendant, among others. As the chair is a well established object in the market, with a huge number of characteristics and suppliers,

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it was decided for choosing among the options available in the market that best fit the counter. So, the specification created and used in the simulations was of a high chair (box type) with the largest seat height adjustment available, back and arms adjustable supports, highly standard material casters and other wished characteristics, such as systems that allow easy mobility for users. To decide on the height of the counter the manikins were positioned on standing and seated postures. As a primary target the height of the female manikin elbow (inferior extreme) was used, avoiding that the height of the new work plan requires extreme movements of the superior limbs of these users during the task. Furthermore, it was verified, by simulations, the decrease on the height of the extreme superior male manikins, as standing as seated. The conception and evaluation of the support for superior and inferior limbs was previous to the user possible future activity, simulating equipment to be incorporated, daily routines performed nowadays and others. Therefore, the objective was to evaluate the necessary space for arms, wrists and hands support without restricting or interfering on each Different sceneries were used (testing combinations implanting technical devices) and simulated with manikins of both extremes, standing and seated. Aiming at lower limbs support a surface named “stage” was used in order to support the feet soles. Such posture has a height adjustment and it follows the “U” shape of the workstation surface, propitiating a spin of 180 degrees with inferior limbs support and comfort. The simulation with manikins of extreme percentiles was able to verify and validate the height adjustment needed for the stage and its relation to the height of the seat, avoiding the swing of the legs. Such posture causes an increase on the pressure made by the attendant’s body on the chair, and consequently, an increase on discomfort.

Figure 2: Height adjustments for feet support

Aiming at the users mobility, it was established the liberation of the inferior part of the counter top by removing the drawer and the CPU horizontal support. The simulations intended to validate an improvement on the chair rotation, on legs

movement, on accessibility to the workstation, a better use of the feet support and alternation on standing and seated postures. In most cases were used especially extreme male manikins to evaluate the new space provided, verifying if the free space would be appropriate for users with larger body dimensions, and if it would also provide a better free space for users with smaller body dimensions. The removal of the drawer of accessories and products brought up the need of auxiliary side furniture. The simulation helped building up sceneries with different proposals, in which it aimed at understanding the new relationships between users and artifacts, especially from an anthropometric point of view. The study of the material handling flow was extremely important to the design of a new workstation which facilitated and minimized the user physical efforts. The main objective was to define and simulate main lines of flow, which in the case of heavy objects, could be only dragged, with no need of lifting or handling in order to avoid physical exhaustion with risks of injuries. To allow better lines of flow and facilitate mobility it was necessary to liberate one of the sides of the counter, i.e., without the presence of fixed objects or equipments, except from the scale, which is a device used at most of the materials handled. The main analysis of this category focused on the inferior female percentile, simulating extreme situations of range and handling of big dimensioned materials. In order to anticipate and validate the conditions of customer/attendant interaction several sceneries were simulated, with percentile variation in both functions. The most critical situation found was on a scenery where the extreme inferior female manikin executed the attendant function seated and the extreme superior male manikin executed the function of the customer standing. The building of the sceneries considered the categories of analysis of visual contact and feeling of inferiority, commonly mentioned in literature about customer/supplier. The relationship between the attendants, focusing on the ability of communicating, could be seen by the categories of visual field and distance between manikins. More than one set of simulation were made, so that it represented multiple attendances. These simulations determined the shape and height of the separation between counters. Closing the categories of analysis, one of the aspects that became evident on the interviews and questionnaires of perception done with the unit operators was the matter of product, cash and personal safety. The main focus of this aspect was the cash drawer, which despite of always being part of the workstation, is now much more accessed because of the latest banking function incorporated by the company in the past few years.

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D. Braatz, Digital Human Modeling and Simulation for Ergonomics Workspace Design

Consequently, cash flow has considerably increased in the units and workers were afraid of robbery. The present drawers are made of wood, being considered heavy, big and often obliging the worker to withdraw from the counter in order to open it, moreover it exposes cash to customers on the other side of the counter. Despite the prescription for workers to close, lock and take the key with them materials handled. The main analysis of this category focused on the inferior female percentile, simulating extreme situations of range and handling of big dimensioned materials. In order to anticipate and validate the conditions of customer/attendant interaction several sceneries were simulated, with percentile variation in both functions. The most critical situation found was on a scenery where the extreme inferior female manikin executed the attendant function seated and the extreme superior male manikin executed the function of the customer standing. The building of the sceneries considered the categories of analysis of visual contact and feeling of inferiority, commonly mentioned in literature about customer/supplier. The relationship between the attendants, focusing on the ability of communicating, could be seen by the categories of visual field and distance between manikins. More than one set of simulation were made, so that it represented multiple attendances. These simulations determined the shape and height of the separation between counters. Closing the categories of analysis, one of the aspects that became evident on the interviews and questionnaires of perception done with the unit operators was the matter of product, cash and personal safety. The main focus of this aspect was the cash drawer, which despite of always being part of the workstation, is now much more accessed because of the latest banking function incorporated by the company in the past few years. Consequently, cash flow has considerably increased in the units and workers were afraid of robbery. The present drawers are made of wood, being considered heavy, big and often obliging the worker to withdraw from the counter in order to open it, moreover it exposes cash to customers on the other side of the counter. Despite the prescription for workers to close, lock and take the key with them whenever they leave the station, the observation of real daily routine shows that it was not followed, mainly by repeatedly short moves. To improve this situation, the new counter was designed with a metallic cash drawer, fitted and with top opening after the system command. This way, the drawer is only opened through command under specific situations (the moment of receiving money or giving change back to customers), and to lock it users just have to close them (without any physical effort because of its light weight of the

metallic top). The simulations confirmed that there is no need to withdraw to open the cash drawer and that, when it is closed, its surface can be used for other tasks. Another advantage of such drawer is that the moment it is opened, its top blocks eyesight and reach site of the person across from the counter, which brings more safety to users. Such advantages were confirmed in simulations of daily routines focusing the customers’ eyesight and the reach of envelopes. Some of the simulations and analysis presented are in figure 3.

Figure 3: Simulations and analysis made during the development of the design project (reaching areas, task surface and customer/worker relationship).

From digital prototyping it was built the first physical version of the attendance counter. Therefore, the designed furniture for physical prototyping confirmed several concepts with bigger trustworthiness to technical specifications, like symmetry, free area under the counter, closeness to most used equipments, perception of safety because of the new cash drawer, and others, as shown in Figure 4.

Figure 4: Attendance counter physical prototyping.

4.2. Case study 2: workplace design in manufacture In the second case study was approached a company a large multinational corporation that manufactures surgical and hospital, first-aid, children hygiene, oral hygiene, pharmaceuticals, women hygiene products and other health products. With a main building in the United States, nowadays the corporation has productive units in 51 different countries, being in Brazil since 1933. The present building is installed in the countryside of São Paulo state with a number of 4500 employees average. The demand for the project dealt in this study was brought up after a partnership among the company and UFSCar in terms of application, development and improvement of the ergonomics analysis and later on develop concepts to critical situations. The manufacturing station designed consists of a workstation of supply support (known as combs) with surgical needles aiming at later chemical processing, being qualified as highly risk potential

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because of its repetition, high precision movements and great demand of attention. Basically the tasks performed in this workstation are: to catch the empty comb (positioned on the left side of the bench) and place it on the device positioned in front of the operator; get a box of needles (on the table) and place 30 needles neatly on the table; pinch manually each needle and place one by one in the comb (where there are small slots that fit each needle); fill in all the slots and then lock the comb (which has a device that locks the needles in the slots). Finally, the operator positions the comb filled with needles on a holder placed on the right. Figure 5 illustrates the workstation before the intervention.

Figure 6: Defined subsystems

These subsystems were important in order to analyse and evaluate relevant and priority questions at different places and time line. In figure 7 two developed and validated prototypes are presented. Figure 7-b shows the process of validation with an employee of the company, located at the present workstation.

Figure7:Physical prototyping of subsystems Figure 5: Workstation before the intervention.

The whole design process lasted for two years and it is composed of the following phases:  Ergonomics analysis with the EJA;  Analysis of the situation of the highly risk activity;  Analysis of the new concept of the new workstation in several subsystems;  Beginning of the design process considering project restrictions and development of parallel subsystems;  Confection of mock-ups (model in natural scale) for experimentation and validation of the conceptual assumptions referring to the main subsystems;  DHMS of the global system;  Ergonomics analysis of the global concept on a digital environment with the use of EJA.  Finalization of technical specifications. It is important to point out that EJA, the instrument that generated the demand was used to validate the final design proposal in digital environment. The project was characterized for the concept evolution of subsystems that, for a better development, was divided into 6subsystems as shown in Figure6.

Based on the analyses resulting from initial developments of the subsystems it was possible to start a global concept building with the help of computer graphic tools, especially Digital Human Modeling and Simulation. The requirements for the project of design of a global solution were discussed from the desired characteristics, and there were as categories of analysis the moves and postures of the worker and the productivity of the system. On conception and validation of the Table subsystem the main contribution of Digital Human Modeling and Simulation was the conception of geometry able to accommodate the different percentiles (05 and 95) ensuring the necessary space to perform the task. To this subsystem the main restriction was the small space delimited for the needle feeding module. In order to improve working conditions in accordance with the risk factors established by the EJA instrument, it was projected a support area to the operator’s arms. During the simulation stage it was also defined the need of round shaped borders through the surface of the table, not only because of well human being aspects, as mentioned on the previous example, but also, to facilitate needle handling. The definition of the height and of the whole structure of the table was also developed in digital environment. It aimed at determining an adequate height to the population extremes that were suitable to the adequate group functioning, especially to avoid collisions with the subsystem “channel and

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D. Braatz, Digital Human Modeling and Simulation for Ergonomics Workspace Design conveyor”. Such subsystem defined the minimum limit of height when presented the collision risk with the inferior limbs of the manikin percentile 95 (analysis illustrated on picture 8-b) and ate the same time imposed the top limit because of the need of reach of percentile 05. On the conception of the subsystem “channel and conveyor” several concepts could be tested during simulation stage, especially to the contribution on channel positioning. On a first moment the channel was designed in parallel to the operator’s longitudinal plane (as previously seen on picture 7b), nevertheless, after the digital environment evaluation, and by using the EJA, it was stated the need of inclining the channel 30 degrees anticlockwise, referring to the plan mentioned, as it is shown on Figure 8-a. Such change reduced movement amplitude and risk of repetitive injuries. This change resulted on a big group of alterations on the concept model, positively contributing to the global system project and decreasing uncertainty about its efficiency. In relation to the conveyor simulation allowed to identify the need of dimensional reduction, mainly because of the lack of space available. The stage of the subsystem “tweezers and comb” it was possible to evaluate safety aspects, choosing the tweezers positioning in a place where lower change of risks to the operator without compromising production (see Figure 8-d). Developing the subsystem of mobility cart significant contributions were found as consequence of the application of modeling techniques and digital human simulation, the main one being, the conception of the spinning system connected to the base of the mobility cart. At first, the projected cart had a fixed system and the final position of the comb was out of the reach zone determined by the project requirements, and that could only be seen through simulation with percentile 05. However, with the aggregated changes along the project and the necessity of reaching the demands of EJA, the project was changed by adding a spinning system which allowed the approximation of the comb to the operator and a better catching position. Such changes made feasible the reach of all population determined and considerable decrease on flexion movements of the spine and wrists, positively impacting on the evaluation made by the EJA. On the conception of the subsystem of comb support DHMS directly contributed to establish support characteristics and the systems of adjustments needed aiming at the reach of the operators, according to Figure 8-c. The possibility of adjustment directly contributes to the increase on regulation space so that allows individual variability, including on the modus operandi.

Figure 8: Simulations

The conception of the discards of needles was a result from developments during simulation stages. The need of this subsystem emerged due to rigorous safety systems, mainly distinguished by the existence of a great number of optical sensitive devices. Thus whenever a failure in the tweezers or channel system occurred (for example, the insertion of two needles at the same time) there would be necessary the operator to interfere on the process. With the conception of this subsystem the needles detected by the sensors as out of pattern were automatically discarded. The subsystem was designed when almost all other devices were already on a more advanced stage of conception, which led to an additional difficulty of physical allocation of this global system. DHMS contributes significantly on the comprehension of the complex special restriction existing by analysing in details equipments and the possibility of physical impact with the inferior limbs of manikin percentile 95. From digital prototyping it was possible to build technical specifications of the new workstation, joining various factors and equating human wellbeing and productivity matters. 5. Results The results are compatible with the benefits mention in the present study: decreasing time development, helping communication and, especially, considering ergonomic factors in advance. Specifically, for each study there may be mentioned some facts that denote the obtained results. For the first case the use of virtual prototyping as a communication facilitator between the professionals involved in the project (group of work composed by company operators and researchers). The anticipation of visual sights of the attendant and customer was of great help for designing, and, finally, several perchance on few milimeters were made on the virtual environment, saving time and anticipating ergonomics reconsiderations after usage. On Table 1 are synthesized the main contributions of DHMS in this specific case.

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Table 1. Main contributions obtained on the development of the attendance counter

Table 2. Main contributions obtained on the development of the manufacture workstation.

6. Conclusion

For the second case the use of simulation can be highlighted as a means of communication between designers and engineers of the contractor company, aiming at validation of the proposed solutions under consonance with the company policy and available technologies. Another specific point of this case study to be considered was the use of the software as a designing tool, equating several restrictions and conflicts of geometric characteristics of the workstation. Table 2 shows some of the main contributions.

It was able to verify the versatility for applying modeling and human simulation and the benefits succeeded from this technology in both case studies. One clear differential between the case studies presented was the interaction between the act of designing and the analyses from simulations. On the development of the manufacture workstation (case study 2) modifications on project resulting from simulations were frequent and conducted the designing process during the global concept detailing. However, despite of the influences of human simulation on the conceptual project of the attendant counter (case study 1), it acted with greater emphasis validating and mediating the ongoing social process than a small technical tool of project development. The cases of application demonstrated show that more and more this technology can be adopted by organizations of diverse sectors which aim at new competitive advantages improving work conditions and contributing to productive effectiveness. However, matters like well-prepared operators, the need of know-how in the areas of project, ergonomics, biomechanics and computing, besides the capacity of analysis and syntheses of the results generated, are necessary requirements, and, hence, challenges for the use of this technology. Another matter that must always be considered in this type of simulation is that the “digital operators only do what they were programmed to do”, i.e., simulation is highly dependent of the view of the task the operator of this technology has, or, that has available, so that subjective traits found on real task performance not found in simulation, or even, present significant differences between the real task done and simulated, due to its deficient perception, able to compromise the real efficiency of the whole designing process. Results presented show that using this technology on a structured and conceptually based way, can be considered an

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D. Braatz, Digital Human Modeling and Simulation for Ergonomics Workspace Design

auxiliary instrument on the search of consideration of the probable future activity and identifying possible constraints on projects of productive situations. On the other hand, it is important to understand that such tool is proper from classical Anglo-Saxon ergonomics, of a highly technicality matter, with emphasis on biomechanical factors, anthropometric and with big focus on quantitative analyses. Thereby, it comes to a conclusion that the challenge is on the use of such applications incorporating the daily work activity as reference situations, allowing that evolutionary sceneries can be developed, discussed and validated by using this mediator object among several agents of workstation designing processes. References BERTONCELLO, D LOPES, M. T. R.; SIMONELLI, A. P.; SOUZA, T. O.; MENEGON, F. A.; MENEGON, N. L.; SILVA, F. F C.; COSTA, D. C.; PRIETO, A. M. C.; AZUMA, S. S. S.; MELO, D. B. Utilização de instrumento para caracterização de fatores de risco: resultados de uma aplicação em larga escala em linhas de produção. In: ABERGO, 13, 2004, Fortaleza, Ceará, Brasil. Anais… Fortaleza: ABERGO, 2004. BRAATZ, D.; MENEGON, N. L.; COSTA, M. A. B.; BERTONCELLO D. Aplicação de Dados Antropométricos Bidimensionais na Construção de Manequins Humanos Tridimensionais. In: ABERGO, 12, 2002, Recife, Pernambuco, Brasil. Anais… Recife: ABERGO, 2002. BUCCIARELLI, L.L. Designing Engineers. Cambridge, Massachussets: MIT Press. 1994. DANIELLOU, F. Lérgonomieet les acteurs de la conception. ConfeencesThematiques. Ergonomie et ingenierie. p. 27-32, 1995. DANIELLOU, F. Aanálise da atividade futura e a concepção de instalações externas. In: DUARTE, F. (org.), Ergonomia e projeto na indústria de processo contínuo. Rio de Janeiro, p. 75-83, 2002a. DANIELLOU, F. Métodos em ergonomia de concepção. In: DUARTE, F. (org.), Ergonomia e projeto: na indústria de processo contínuo. Rio de Janeiro, Ed. COPPE/UFRJ e Lucerna, p. 29-33, 2002b. DANIELLOU, F. A análise do trabalho: critérios de saúde, critérios de eficácia econômica in CASTILLO, J. J., LÓPEZ, J. V. (Org.) – Ergonomia. Conceitos e Métodos. Lisboa: Dinalivro, 2005. FEYEN, R.; LIU, Y.; CHAFFIN, D.; JIMMERSON, G.; JOSEPH, B.; Computer-aided ergonomics: a case study of incorporating ergonomics analyses into workplace design. Applied Ergonomics, 31, p. 291-300, 2000. FONTES, A. R. M. ; BRAATZ, D. ; BERTONCELLO, D. ; SANTOS, L. M. ; MENEGON, N. L. . Projeto de Guichê de Atendimento Contextualizado pela Análise

Ergonômica do Trabalho. GEPROS - Gestão da Produção, Operações e Sistemas, v. 2, p. 111-124, 2006. MAGISTRIS, G.; MICAELLI, A.; EVRARD P.; ANDRIOT, C; SAVIN, J.; GAUDEZ, C.; MARSOT, J.; Dynamic control of DHM for ergonomic assessments, International Journal of Industrial Ergonomics, Volume 43, Issue 2, March 2013, Pages 170-180 MENEGON, N. L.; BRAATZ, D.; SECCHIN, V. M. S.; REGAZZINI, M. L. L.; LA SALVIA, A. B. N.; PEREIRA, W. A.; NAVEIRO, D. M.; ZAMBERLAN, M. C. P. L.; PASTURA, F. C. H. Pesquisa Antropométrica Embraer. In: ABERGO, 12, 2002, Recife, Pernambuco, Brasil. Anais… Recife: ABERGO, 2002. MENEGON, N.L. Projeto de processos de trabalho: o caso da atividade do carteiro. 2003. 259 p. Tese (Doutorado). COPPE/Universidade Federal do Rio de Janeiro, Rio de Janeiro, 2003. SCHAEFERS, D.H.; RUITER, I.A.; SONG, Y.; MOLENBROEK, J.F.M. Requirements for an industrial designer-oriented DHM. In Proceedings of the First International Symposium on Digital Human Modeling. 2011, Lyon, France. SIZEGERMANY. Press information. In: www.hohenstein.de/ximages/1399929_sgabschlus. pdf.2010. ZIOLEK, S. A.; KRUITHOF, P. C. J. Human Modeling & Simulation: A primer for practitioners. In: HFES, 44, 2000, San Diego, USA. Proceedings... San Diego: HFES, 2000.

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