Methodological advances in workplace ergonomics – from risk assessment sheets to digital simulations

September 27, 2018
Workplace ergonomics

As a discipline, ergonomics has always had a rather peculiar relationship with technology. Glancing through its history, it becomes clear that this field has always been rooted in methodologies, databases, guidelines and principles -- in short, academic knowledge. Ergonomics was -- and still is -- dependent on the state of technology because it cannot innovate and engineer novel technical solutions in isolation. Therefore, the comprehensiveness of the available technological toolkit for ergonomic analysis is dependent on the prevailing incentives and motivation to invest in discipline-specific developments.

Because of its history and this strong dependence on other fields, ergonomics experts are inclined to use traditional methods and approaches during ergonomic assessments. These usually consist of checklists, risk assessment sheets, guidelines or other techniques that use paper and a pencil. Paper-based information or evaluation has been around since the birth of ergonomics, which dates back to the first anthropometric databases created for military purposes. Since then, this conventional medium has dominated the field and many market-leading companies still conduct risk assessments in paper-based formats.

These risk assessment methods usually incorporate some sort of scoring system, which determines the overall ergonomic adequacy of a given workplace. This numerical categorization provides a somewhat objective system that helps ergonomists to identify possible deficits and to compare the ergonomic appropriateness of different workplaces with each other. The final score is based on numerous factors, which may concern the work environment, the working postures, the work tools or other aspects, depending on the comprehensiveness of the method. The Rapid Upper LimbAssessment (RULA) sheet, for example, focuses mainly on body postures, whereas the ergonomic Assessment Worksheet (EAWS) considers an extensive range of factors during evaluation. This means, however, that the scores of different assessment methods cannot be compared with each other, as they are derived from highly-distinct calculation processes.

These risk assessments only enable the identification of possible risks, and they can not be used to detect where and in which form they may actually occur. The experience and know-how of the ergonomist is required to pinpoint the exact source of hazards (like a certain posture or work task segment) and to develop a workplace overhaul program to redesign the workplace elements that cause the deficit.

Another disadvantage of these techniques is that they are only applicable to existing and well-established work tasks through a framework of so-called “corrective” analysis. This means that a workplace that is still being designed cannot be evaluated, because there are not yet any tangible sources of information regarding the working postures and movements, or even the work environment. So paper-based ergonomic risk assessments cannot be incorporated into the early phases of a workplace development project.

Despite the disadvantages, these traditional risk assessment methods have not become obsolete because they provide ergonomists with more or less unbiased scoring scales to evaluate workplaces. What has become obsolete, however, is the way the data is gathered for the calculation of the scores. Most of the factors that determine the final score require accurate data to ensure the authenticity of the evaluation – such as in the Rapid Entire Body Assessment (REBA) risk assessment where the position of the body segments primarily determines the final score. However, the established method among ergonomists is to simply observe the worker over several work cycles and then estimate the effect of the specific factors.

Another similar approach consists of recording the work task on camera and then analyzing the recording using still frames to find the most inconvenient postures and measuring the position of the body segments with a ruler and protractor. Not only is this method inefficient but it is also inaccurate because it is impossible to measure the exact angles of a 3D human’s posture on a 2D photo.

It becomes clear that gaining accurate and objective data for analysis is essential and doing so in digital form is even better – for the sake of computerized analyzability and its feasibility for subsequent evaluation. A convenient solution is presented in the form of motion capture systems, which are able to record the movements of a human and convert it into a digital animation. Such systems are utilized in a wide range of areas, like video game or movie animations, virtual reality systems, healthcare, and naturally ergonomic assessments. In terms of the latter, the capability to record actual and precise locational data about the body postures in 3D is the most important specialty of such systems. 

This method eliminates the twofold problem of objective data gathering and digitalization. But despite how appealing these solutions may look like, they can still be regarded as incomprehensive if used for ergonomic analyses, because the data still has to be transferred somehow to a risk assessment system to calculate risk scores. Gaining objective data and still using paper-based evaluation sheets is impractical; transferring the data to a digital risk assessment software is somewhat better. Still, in case of the latter, the incompatibility of such programs and the need to manually transfer the data makes this a time-consuming process. Thus, the need arises for an all-around digital platform that encompasses the whole toolkit for a risk assessment, that is, from the processing of the movements until the calculation of the risk scores.

Digital dawn

To understand how traditional methodology becomes part of modern, computerized product development workflows, we must take a glance at the history of digital ergonomics and its advancement. The most important aspect in such developments has always been to create an accurate representation of a human model which can be used for testing and approval of product prototypes. Four different generations of such technological solutions can be observed. The first generation only consisted of 2D models, mainly paper templates. These human representations were created specifically to support planning processes and to help to implement ergonomic aspects into the initial product design stages. Stand-alone, digitalized human models appeared in the second generation, and they were anthropometrically representative and adaptable to the framework of the assessment – with customizable body proportions and percentages. 

As the digital platform became predominant in every area, the need arose for ergonomics to be able to be implemented into an increasingly complex and sophisticated product lifecycle management systems. Thus, an extensive integration of digital human models into CAD software frameworks took place in the third generation. These newly developed computer-aided anthropometric assessment programs were and are still used for evaluating the dimensional adequacy (as in adjustability of the work surface or the reachability of control units) of products in the digital space, mainly vehicles and small-scale workplaces that were still in the development phase. The fourth generation concerns solutions that can utilize fully immersive virtual reality, and systems that are still under development.

The earlier CAE (Computer Aided Ergonomics) systems could be primarily used for conceptive evaluations, that is, assessments which take place in the initial phase of product development where no physical model is present, only digital CAD models. The state-of-the-art solutions, however, are capable to process captured motion data and apply it to the digital human model they employ. This enabled ergonomists to analyze such workplaces that are already functional and in use, and gather authentic data regarding the ergonomic adequacy of a given workplace.  Furthermore, modern CAE programs are equipped with built-in risk assessment modules, which enables the user to immediately calculate the risk scores of the workplaces and modify the construction or arrangement of the workplace in quick iterations.

Even though that the current top-notch solutions for ergonomic analyses can drastically reduce the product development time, the knowledge and expertise of an experienced ergonomist are still indispensable. The data gathering and -processing stages are augmented by computerized calculation power, but the interpretation of the derived information is a manual task. The actual modification plan regarding a deficient workplace must be developed manually, as the software programs are still unable to give specific advice about the adjustments needed. Nevertheless, nowadays’ digital ergonomic solutions provide an immense amount of information in the blink of an eye, which was impossible to imagine back then, and as product management systems become even more complex and comprehensive, so will digital ergonomic solutions follow this track in the future.

 

Tamás Fergencs

Junior Human Engineer

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