Virtual Human Engineering Plugin Dipl. Des. Dipl. Inf. László Ördögh Dipl. Math.Inf. Klára Gehér Virtual Human Engineering GmbH Dr. -Ing. Christiane Kamusella Institute of Material Handling and Industrial Engineering, Professorship of Ergonomics, Dresden University of Technology Dipl. Inf. Csaba Szeredy NexStep Consulting Kft.
ABSTRACT The aim of this paper is to provide fundamental knowledge and key information about the virtual human engineering development process carried out as a joint project of Virtual Human Engineering GmbH, the NexStep Consulting Kft. and Institute of Material Handling and Industrial Engineering, Professorship of Ergonomics, Dresden University of Technology. Further, we intend to resume future goals of this project. Consequently our aim is not to disclose the results of a specific research area but to summarize the achievements of an intense working period, in order to make the work of this research- and development team known for a wider professional audience (community). Crucial elements of the development strategy are the following components: Development of a virtual reality human simulation plug-in core system and its implementation in various hardware/software/network environments Laptop, Desktop, Immersive stereo VR environment, Massively Multiuser Online Virtual Environment, Metaverse. Development of a digital ergonomics tool kit that is able to support and assist the work of engineering teams working on conceptual and corrective ergonomic analysis and quality assurance by taking into account European, national and international ergonomic standards. Development of a new method of workflow that enables the research team to take advantage of all the new collaborative features offered by the Internet. Keywords: ergonomics tools, man models, product development process, digital prototyping
INTRODUCTION Nowadays nobody would argue about the fact that ergonomics can substantially enhance the quality of products and services. Decision makers of small and medium sized enterprises, as well as decision making bodies of global concerns consider ergonomics as a component of strategic importance. There is a wide range of products and services in the case of which a proper ergonomic analysis would be indispensable. They would not be able to serve their purpose properly without engineers considering human factors during planning and realization. Even if the benefits are understood and appreciated, it is still a question whether it is economically feasible for a company to invest in the technology and to maintain it. Today's sophisticated professional virtual human engineering tools have a wide range of performance but belong to a price category that is generally unaffordable for small and medium enterprises. Even most universities can only have access to those human engineering tools if they get a substantial allowance. After some market research we got a notion about the price category that could contribute to a widespread use of these human engineering tools. Based on this research Virtual Human Engineering GmbH and Institute of Material Handling and Industrial Engineering, Professorship of Ergonomics, Dresden University of Technology set the aim themselves to develop a technology environment with the most up-to-date human engineering know-how that would be available for a moderate price.
1. BASE TECHNOLOGY & PLUGIN In broad outline a computer aided ergonomics simulation system consist of two crucial components. The first component contains all those performances that handle the elements of the environment that is indispensable for the simulation. The spectrum ranges from tasks related to the operating system until the construction and visualization of elements building up the simulation environment. The second component consists of those modules that implement the specific professional knowledge that is needed for a proper ergonomic analysis. A software product that is restricted to the implementation of professional knowledge in the field of ergonomics requires a complementary basic technology that is able to provide the commonly used high quality geometry and rendering tools. Furthermore the implementation of professional ergonomics knowledge should complete these features in a fully integrated way. Fortunately, the sophisticated professional CAD and VIS software products that are prepared to plug-in technology are fairly wide-spread and are in most cases affordable even for small and medium enterprises. Today's CAD/VIS/VR technology generally does not have any special hardware requirements. Further, any PC is supplied on hardware and operating system level with all the features that are needed for an on-line collaborative work.
1.1 CHARAT PLUG-IN In computing, a plug-in is a set of software components that adds specific capabilities to a larger software application. CharAT Ergonomics is a virtual human engineering plug-in to the 3dsMAX and ICIDO VDP (Visual Decision Platform) applications that has been developed by Virtual Human Engineering GmbH. CharAT Ergonomics takes advantage of all features of the basis systems and completes them by the implementation of the following performances: File system operations with own data content Transformation of data retrieved from anthropometric databases to graphical representation Features enabling the user to create kinematic chains and to edit their properties (bone degree of freedom and assignment system, tracing of six target points simultaneously with inverse biomechanics) Features enabling to user to define and to edit components of graphical representation (integration of 3d scan, shape, skin, texture, rigging, animation dependent morphing) Features enabling the user to program time-dependent dynamic events on a time-line (VDP version: motion capture + key-framing, 3DSMAX version: key-framing) Human engineering expert modules (static and dynamic space requirements, real time collision analysis, reach envelope, field of vision analysis, strength analysis , discomfort analysis) Controlling of several different avatars in a virtual scenario Dynamic monitoring of data coming from several different avatars Features enabling the user to associate kinematic chains of virtual human figures and kinematic chains of environmental elements Documentation of ergonomic analysis results
1.1.1 Industrial Avatar CharAT Ergonomics Plug-in generates 3d graphical representation of human avatars based on data retrieved from various databases. Regarding industrial avatars, it is a requirement of primary importance that the properties of the 3d graphical representation of a human figure should meet to the best possible extent the ergonomic and biomechanical properties of real human figures. CharAT Ergonomics creates the 3d avatars considering nationality, gender, age, percentile, proportion, somatotype, acceleration. In addition to the built in standard databases the designer is in the position to create and integrate his own database in order to retrieve data from it while testing the design configuration.
CharAT Ergonomics is provided with the following built-in databases: DIN30402 (2005) DIN EN ISO 3411_2007 DIN 5566-1 (2006) Daten des Europamenschen (gesicherte arbeitswiss. Erkenntnis Nr. 108) DIN EN ISO 3411_2007 ANTHROPOLOGISCHER ATLAS (Flügel/Greil/Sommer, 1983) BODYSPACE (Pheasant, 1988)) Internationaler anthropometrischer Datenatlas (Jürgens, BAuA, 1989) DIN 5566-1 (2006) BSI PP 7317 ISBN 0580 15391 1987 Ross & Wilson UHP database 1976-1996 JAPAN Database Institute of Bioscience and Human-technology 1994 UIC 651 VE NASA STD 3000(2000) User defined database
FIGURE 1.1 CharAT Ergonomics standard database regions
A CharAT Ergonomics skeleton model consists of scripted bone elements. The number of bones can range from one up to two hundred. The user is in the position to configure the skeleton model by setting different parameters of the scripted bone elements. The freedom of choice regarding configuration and parameter setting ensures a high level of flexibility and enables the user to adjust the skeleton model to the objectives of the actual design process and ergonomic analysis. A data management system handles the results and partial results of the ergonomic analysis. A special file format with the corresponding file extension ensures the saving and retrieving of data in an organized form. All performances of CharAT Ergonomics are in the data management system integrated. Partial results can be saved in order to be integrated in subsequent projects. Different saved states of projects are 100 per cent reproducible. High documentation quality, as a basis of cooperation between ergonomists and designers, is guarantied. Different body parts of the 3d human figure can be positioned by an interactive procedure intuitively or by precise setting methods, in order to bring the figure in the wanted body posture. Rotatory and translatory motions of kinematic chains can occur free in three-dimensional space or alternatively, the kinematic chain can be driven to a special target point of the simulation environment. Fast, intuitive and reliable positioning methods and inverse biomechanics are at the user's disposal for an effective static and dynamic space requirement and activity analysis.
Different ergonomic analysis tasks may require different graphical representations. CharAT Ergonomics is provided with a modular graphics tool kit that enables the user, on one hand, to define the level of detail regarding the integrated graphical representation, on the other hand, to decide which graphic details should appear in the documentation. In the graphical elements' library are not only skins with different levels of detail and whole skeletons listed but ergonomics symbols and objects can be found as well. The user is in the position without any limitation to define and create further body parts (for example internal organs, such as lungs, stomach, intestines) or objects that are indispensable for the design analysis (for example helmet or safety jacket). The created new body parts and objects can be freely assigned to any element of the kinematic chain. The CharAT Ergonomics 3d graphical representation of human figures stands not only for the test person but it is part of the user interactions and of the information flow as well.
1.1.2 Ergotyping tools The primary focus of the development and application of CharAT-Ergonomics is on ergonomic application. Hence the human model computationally implements human attributes that are relevant in order to meet ergonomic requirements in a
specific creative context. Using ergonomic tools, CharAT-Ergonomics helps to plan and assess ergonomic problem solutions. In cooperation with Dresden University of Technology, Chair of Labor Sciences, ergonomic tools are currently being developed, emphasizing particularly the integration of normative ergonomic requirements. At present, the main focus of the cooperation extends to: the development of CharAT-Ergonomics in accordance with the principles of Ergotyping®, developed at Dresden University of Technology (see www.ergotyping.net and Kamusella 2009). Ergotyping® includes methods and digital tools to be used for the analysis, assessment and design of the ergonomic aspects of Digital Prototyping the development of Ergotyping-tools, e.g. visibility requirements for visual display units, see Kamusella 2010a und 2010b; body forces, see Kamusella and Ördögh 2011 As the ergonomic component of Digital Prototyping, the aim of Ergotyping is to include ergonomic requirements at the earliest stage possible in the process of planning and designing man-machine systems. Using digital ergonomic tools and methods, Ergotyping examines components of a man-machine system with regard to ergonomic aspects of product and production ergonomics, digital factory, as well as cognitive ergonomics. Generally speaking, the ergonomic requirements of product ergonomics can be derived from the state of the art and from generally accepted technological regulations and standards. Is the processing of ergonomic assessment criteria in Ergotyping oriented towards the regulations of product safety, the manufacturer of a given product can be assisted in fulfilling his legal obligations. Manufacturers and distributors of machinery and technical equipment have to comply with a number of regulations in order to obtain marketing approval in Europe. Among these is the observation of Appendix I of the General Machinery Directive (2006/42/EG), which includes the obligation to integrate basic safety and health requirements including ergonomics. The manufacturer of any given kind of machinery is obligated to ensure that the machinery is built in compliance with the respective standards and regulations. Thus reference is made to a number of harmonized standards representing the state of the art. If machinery has been produced in accordance with these harmonized standards published in the Official Journal of the European Union, it is assumed to meet the basic safety and health requirements covered by the respective standard (presumption of conformity). This also means that ergonomic requirements have to be included in the Construction Products Directive, with a structured design process being presupposed. Additionally, documentation of the meeting of ergonomic requirements is required in order to ensure the compliance with the aforementioned harmonized standards. The development of Ergotyping tools is done in such a way as to ensure the implementation and processing of ergonomic knowledge from the harmonized standards in an application-oriented manner, while integrating additional knowledge from other fields. This process is complemented by an appropriate report which includes proof of all sources and can thus serve as a basis for the technical documentation. In order to process individual
ergonomic insights, a stage model specifically developed to this end (see figure 1.2, Kamusella 2009) is used which encompasses several sources of knowledge.
FIGURE 1.2 Stage model for the implementation of ergonomic aspects in the field of machine ergonomics STAGE 1 contains the ergonomically relevant contents of harmonized standards Type A and Type B (basic and product standards) that apply to several kinds of products and represent the state of the art. If no harmonized standards are available, national standards and technical specifications from Section 2 of the list of standards can be used if regarded as relevant and helpful.
STAGE 2 is based on ergonomic requirements from further fields of knowledge, such as state regulations, regulations of insurance carriers, confirmed ergonomic findings, specialist literature etc. The previously developed Ergotyping tools, "assessment of visibility" (see Kamusella 2010a and 2010b) and "body forces" (Kamusella and Ă–rdĂśgh 2011), use this stage model for the research and processing of ergonomically relevant information. At the man-machine interface, ergonomical requirements applicable to the elements of information recording are to be integrated into the design process. This affects for instance optical display units used in machinery facilities, measuring devices, dashboards, control panels and monitoring devices. The Ergotyping tool "assessment of visibility" deals with user- and product-oriented parameters for the performance of analogue and digital displays and provides them with attributes according to Stage 1 and 2. The program module allows for a calculation and a visual display of icons, alphanumeric elements and analogue scales with intervals of one, two, or five. Determined by the man model's viewing distance from the display area, these figures are generated with optimal and approved parameters. Taking into account the distance and the alignment of the display area and the eye, the agedependent minimal and the fatigue-proof near point for different users, changes in visual acuity as well as visual angles are determined and assessed. Visual fields can be shown in one scenario. One display area is connected to the eye camera of
CharAT Ergonomics and controls eye and head movements simultaneously. Calculation results for the display parameters and further ergonomic assessment are released dynamically and in real time. With regard to the viewing distance, the recommended reference values depend on the accuracy requirements of the respective visual task. Using recommended and approved visual angle values, the size of the figures is displayed quantitatively and graphically depending on the viewing distance. The human eye has the ability to maintain a clear focus on an object even as its distance changes. The program module includes parts of this ability, namely the near accommodation. Interactively placing a viewing surface in front of the CharAT Ergonomics eye, the viewing distance is assessed, using the age-dependent accommodation near point calculated for a certain age in which wearing glasses cannot be considered the rule yet (until the age of fifty). Reducing the minimal viewing distance leads to a defocusing of the object. Increasing defocusing reduces the acuity which is calculated based on existing visual acuity values and then displayed dynamically in the program module. Proof of the ergonomic sources used is documented. When focusing on a viewing object, the visual axes in CharAT are aligned depending on the viewing distance (fusional vergence) by simulating an eye vergence movement that is controlled by the viewing object. This is relevant to the representation of monocular vision and monocular fields of view. In order to direct the gaze to the target objects, the line of sight can be adjusted in such a way as to make a serial eye-head-body-coordination occur within interactively predefined comfort zones. During the machine's life phases, activities involving the application of force occur. These activities are characterized by different postures, body movements, positions of limbs, and directions of force. The Ergotyping tool "body forces" (s. Kamusella and Ă–rdĂśgh, 2011), which is currently under development, is used as a basis for the development of a methodology and a tool for the determination and assessment of body forces. The ergonomics tool can be used for both as-is analyses and strategy analyses. It serves to qualitatively estimate and quantitatively determine isometric action forces in the arm-shoulder-system and the whole-body-system. Data from existing force standards has been examined and collected in different databases using a multidimensional indexing system. A people-oriented polar coordinate system was the first choice because it is anthropometrically independent and reproducible. All data already existing in polar coordinates was collected in the databases. Regarding the elevation angle, the azimuth angle and the arm spans, value ranges have been defined, for which the point of force application can be clearly assigned. Force data from the Montagespezifischer Kraftatlas ("Installation-specific Force Atlas", Wakula a. o. 2009) is available for posture variations. In order to clearly assign these to one of the body positions in CharAT, tolerance ranges have been defined in Cartesian coordinates for the position of the point of force application. The tolerance ranges for different percentile ranks have been differentiated according to gender. In a control dialog, the user can choose between evaluation
procedures:  (normative) evaluation procedure, based on the maximum static action forces collected in the national force standards The action forces of various postures are collected in a database. During the planning analysis, the user is first provided with force tendencies in reaching spaces differentiated according to percentile rank and gender and dependent on posture and the specific manner of force application. Levels of force are shown which contain color-coded dots representing the force application. Above these, the force tendencies are displayed. If the user decides on a concrete point of force application and switches to detailed planning, concrete maximum and recommended action forces are calculated, taking into account specific factors relating to the person or activity. These values are displayed in the monitor dialog; additionally, a risk assessment is carried out.  Montagespezifischer Kraftatlas ("Installation-specific Force Atlas") The user preselects the basic posture (standing, sitting, or kneeling) and defines the direction of force as well as the manner (one-handed or two-handed) and frequency of force application. The height, distance and asymmetry of the body in relation to the point of force application are calculated within the program according to percentile rank, age, and gender, and assigned to an appropriate database entry. If dynamic changes of the point of force application occur, namely in case of hand movement and posture adjustment of CharAT Ergonomics, the resulting maximum and recommended action forces within one basic posture are updated and displayed in real time. The health risk the specific force application carries is evaluated according to a three-zone model ("traffic light" scheme). During its change of position the point of force application, typified by the hand-target of CharAT, is analyzed in real time for all force directions in the as-is analysis. Taking into account every influencing factor, a recommended force is calculated and a subsequent risk evaluation carried out.
2. ONLINE WORKFLOW Besides efforts taken in order to optimize hardware and software architecture our research team lays great emphasis on the optimizations of workflow. In the focus of our attention are most of all those intranet and internet features that enable the collaborative work of geographically separated professionals. In addition to methods supporting traditional intranet client server architecture, internet based cloud computing methods and Multiuser Online Environments are getting increasing emphasis. In the case of internet based solutions we pay extreme attention to data safety. We have tested different workflow organization methods and work environments in the framework of real and concrete projects. The projects corresponded to different types of working relationships, for example teacherstudent relationship in an educational environment. In the course of the Phiamo Electro Car Project workflow we tested the working relationship of a package
designer, a car bodywork design engineer and an ergonomist in a cloud computing environment. Participants of the Cruzbike Cuervo Project were a bike producer company from the United States, a designer from Australia and a German ergonomist. The experiments regarding workflow and working environment are going on and after analyzing the gathered experiences we intend to optimize tool kits for different types of working relationships and working environments.
FIGURE 1.3 Human engineering GUI in collaborative environment
REFERENCES Kamusella, Chr.; Schmauder, M. 2009: Ergotyping im rechnerunterstützten Entwicklungs- und Gestaltungsprozess. In: Zeitschrift für Arbeitswissenschaft, Ausg. 03/2009. Hrsg. Gesellschaft für Arbeitswissenschaft e. V. ISSN 03402444, Ergonomia Verlag Stuttgart. Kamusella, Christiane 2010a: Ergotyping-Tool Sichtanforderungen für optische Anzeigeeinrichtungen. – Wissensportal: www.baumaschine.de Archiv: 02(2010). Kamusella, Chr.; Schmauder, M. 2010b: Ergotyping-Tool „Sichtbewertung“. Dokumentation des 56. Arbeitswissenschaftlichen Kongresses der Gesellschaft für Arbeitswissenschaft in Darmstadt, 24.-26.03.2010, GfA-Press Dortmund 2010, S. 135-138. Kamusella, Chr.; Ördögh, L. 2011: Ergotyping-Tool „Körperkräfte“. Dokumentation des 57. Arbeitswissenschaftlichen Kongresses der Gesellschaft für Arbeitswissenschaft in Chemnitz, 23.-25.03.2011, GfA-Press Dortmund 2011, Veröffentlichung in Vorbereitung. Wakula, J.; Berg, K.; Schaub, Kh.; Bruder, R.; Glitsch, U.; Ellegast, R.: Der Montagespezifische Kraftatlas. BGIA-Report 3/2009, Hrsg.: Deutsche gesetzliche Unfallversicherung Berlin.