Virtual Prototyping State of the Art in Product Design Hans-Jörg Bullinger, Ph.D Professor, head of the Fraunhofer IAO Ralf Breining, Competence Center Virtual Reality Fraunhofer IAO Wilhelm Bauer, Ph.D, member of the Institute leader group Fraunhofer IAO Faunhofer Institute for Industrial Engineering (Fraunhofer IAO) D-70569 Suttgart, Nobelstr. 12, www.iao.fhg.de, ralf.breining@iao.fhg.de Abstract Digital mock-ups (DMU) are the platform for Virtual Prototyping (VP). Therefore, questions concerning VP are focused on the integration of computer-based tools and methods for DMU. Which reliability concerning the assessment of product characteristics do digital mock-ups have? What kind of representation/visualization is necessary to achieve a high reliability [4] concerning the assessment of product characteristics of digital mock-ups? Which possibilities do we have to interact with the digital mock-ups directly? To find valid responses to the mentioned questions we have to look to immersive projection technology (IPT) systems [2]. 1. Introduction Virtual Reality (VR) is well introduced and highly accepted in the international society of institutional research. But does the manufacturing industry share this excitement about VR and especially Virtual Prototyping? How to identify fields of application and how to get return on invest? These questions will be addressed especially for the automotive industry. While some of the considerations hold for other manufacturing industries as well, some do not. Digital Mock-Up (DMU) is the keyword for innovative product development processes. DMU is a complete digital product description for development, design and manufacturing. The basic conditions are well-known: product life cycles decline drastically and technological leadership of the highest possible quality is required in order to keep pace with the ever increasing innovation dynamics. The use of computer-aided development tools is essential. DMU is the platform to digitally integrate these tools. 1999 will be the year of DMU that are the basis for Virtual Prototyping (VP). Digital Mock-Ups are the platform to integrate computer-based tools and methods. The use of computer-based tools and methods is essential respectively the actual economic conditions. Engineers have to decrease the time for construction and evaluation of the data. Although the complexity is growing the first sketches must be more detailed and the perception of the different basic characteristics should be guaranteed. 2. Process Innovations Another aspect is that new processes like Rapid Product Development (RPD) focuses on a short while between the final determining of the construction and the start of sale. Therefore methods for VP become more and more important [1]. Although the complexity is growing the first sketches must be more detailed and the perception of the different basic characteristics should be guaranteed. The mainly computer-based development of products offers many advantages regarding optimization of time, costs and quality. But on the other hand it leads quickly to a restricted, reduced perception of the product during the development process. Virtual Prototyping State of the Art in Product Design Page 1 of 5
Digital mock-ups therefore require Immersive Projection Technology (IPT) so as to improve the perception of the computer-based models respective the product. CAE Virtual Production Digital Manufacturing V irtual P roduct Model Immersive VR DMU 3D Assembly Innovation 3D Reference Model 2D Model Part Lists Drawing Config. Mgmt. not integrated Change Mgmt. not integrated Document Config. Mgmt. integrated Change Mgmt. integrated Workflow Life Cycle Paper Drawing PDM Figure 2.1 - Main trends for manufactruing industry (source: Dassault Systèmes) 3. Innovative User Interfaces Virtual Environments (VE) are getting more and more mature. Multi wall stereo projection systems (well know as CAVE TM ) as a special form of display environment recently became manageable because new and powerful computer hardware technology is now available. It presents the user with an immersive quasi-holographic visual impression in adequate resolution. The theme-integrating development of products, as well as the increasing complexity of cause-action-chains, requires new human-machine interfaces. These interfaces must have a high degree of clarity and allow the interaction in the form of human-like behavior through computer-aided tools. The usability of a computer aided design system is primarily influenced by two things, the user interface and the underlying internal model representation. In former times many approaches have been performed by first defining the internal model representation, capable of storing geometric, topological and hierarchical dependencies between components in a model. Less attention is paid to the user interface, job completion and to the subjective feeling of the user about the tool. In fact, the intention and the actual result are considerably different in most announced VR modelers. The designed interface (Figure 3.1) serves the visualization and evaluation of CAD geometry. The evaluation of the geometry which is the real advantage of a VE has therefore top priority. In the analysis the following demands were elaborated. A simple representation of a pointer is needed with the help of which objects can be identified in a virtual room. Additionally the virtual cursor is used as ruler to measure small distances. The virtual cutting is very important Virtual Prototyping State of the Art in Product Design Page 2 of 5
Figure 3.1 - User interface in VE Figure 3.2 Tracked input-device MIKE for the judgement of the objects presented. It enables to see points of the model that are usually hidden. Objects can be separated by differently colored cutting planes. Problem areas of the objects have to be marked for documentation. The actual state of the virtual picture is fixed via the screen shot function in a two-dimensional picture. Automatically there are two images generated, a full size image and a rectangle section, depending on the view position of the user. 4. Application Overview The major weak-point of computer-assisted simulation and design tools which have been available so far is that ideas of three-dimensional geometry and/or functions are handled by two-dimensional input/output media. This disadvantage is being intensified with growing complexity and multi-dimensionality of the problem on hand. An extremely interdisciplinary discussion of the problem scope is aggravated by the existing tools, which are very special tools in the majority of cases, whereas the multi-sensory and immersive systems of VR supported a quick and interdisciplinary visualization of contents [5]. The use of conventional computer systems in such complex processes as the design of product shapes or the evaluation of assembly processes requires the user to have a great ability to think in abstract terms. To gain a more intuitive access to these problem scopes, the problems are to be handled in a VE. The three-dimensional representation of shapes, tools and workplaces in real time and the use of man models will open up new perspectives. These applications greatly differ in requirements for data accuracy and visualization quality. It is obvious that it is not possible for a VR software to support all the different demands "out of Virtual Prototyping State of the Art in Product Design Page 3 of 5
the box". An appropriate VR software has to be a flexible application platform in-stead. The actual VR systems help engineers to deal with different problems: Evaluation of exterior design, Evaluation of production environments, Analysis of thermal comfort and Evaluation of tools. 5. Example for an successful Application in the Automotive Industry The development process of sheet metal forming machines depends highly on the communication of various engineers. Each engineer has his own technical background in a special aspect of these machines. The machines are very complex mechanical pneumatic and hydraulic engines which operate the whole lifetime of a special car. The costs for these metal forming tools are very high and it can be estimated that a better performance in time for the development of such tools would lead to a significant reduction in time for the whole development process of a car. For BMW the Fraunhofer Institute for Industrial Engineering (Fraunhofer IAO) developed a VR application for the evaluation of the CAD data of the sheet metal forming tools in a virtual environment. The CAD data represents the actual state of construction and can be exported for evaluation tasks in the virtual environment [3]. The used CAD system is CATIA with a specialized Generator for Inventor Data. The Fraunhofer IAO has set up the complete working space for Virtual Reality systems. The virtual environment consists of a CRT-beamer with a rear projection on a diffuser plate (3x2,2m), an Ascension Flock of Birds tracking system, a Silicon Graphics Onyx2 Infinite Reality with 2 RM5, special inputdevices (developed and manufactured by Fraunhofer IAO) and an ERCO light system. Figure 5.1 / 5.2: Examples of digital mock-ups in the CAVEEE of the Fraunhofer IAO These requirements led to a room design with two separate colored parts. A soft black colored projection area with the dimension 4x3 m and a soft light gray discussion area 4x4 m. There Virtual Prototyping State of the Art in Product Design Page 4 of 5
are oriented stereo emitter to the discussion area, so that it is possible to demonstrate a stereo view during the engineering discussion around the conference table. One of the most important aspects of this application is, that several engineers (at least 6) have to work together. At any time each of them has to know exactly about what the others are talking. A virtual environment with only one tracked person leads to the development of a 2- hand interaction device. The person with the tracked glasses can interact with one device, the other person can point with the second device. The virtual representation of the interaction devices shows everyone exactly what they are talking about. 6. Conclusion To get 200% digital, a statement of Boeing concerning the development of the 777, becomes an example for all innovative high technology companies. Therefore questions concerning the new processes are based a lot more on digital mock-ups. While the return on invest can be calculated immediately in some cases, in other cases you will just see some excited engineers playing with the new technology. Product development is a creative process and IPTs are creative tools. It is hard to measure the human factor, but company success is based on the creativity of its employees. Acknowledgment Through the project Virtual Reality as a Tool for Design, Evaluation an Co-operation" of the special research area "Development and testing of innovative products of the German Research Society (DFG) several of the mentioned issues could be analyzed, developed and tested at the University of Stuttgart and Fraunhofer IAO. 7. References 1. Bauer, W.; Breining, R.; Rößler, A.: Co-operative, Virtual Planning and Design. In: Proceedings of Virtual Reality World 95. Stuttgart, 21-23 Feb. 1995. München: Computerwoche Verlag, 1995, pp 213-223. 2. Riedel, Oliver; Breining Ralf: Use of Immersive Projection Environments for Engineering Tasks. In: Proceedings of the 25th SIGGRAPH 98, course Applied Virtual Reality, Orlando 21-23 July 1998. 3. Riedel, Oliver; Breining Ralf: Virtual Environments for Visualization and Evaluation in the Automotive Industry. In: Roller, Dieter (Editor). Proceedings Simulation, Virtual Reality and Supercomputing Automotive Applications of the 31st ISATA, Düsseldorf 2-5 June 1998, pp 193-200. 4. Bullinger, Hans-Jörg; Riedel, Oliver; Breining, Ralf: Perception in different IPT-Systems. In: Proceedings of the 2nd International Immersive Projection Technology Workshop. Iowa 1998. 5. Bullinger, Hans-Jörg; Blach, Roland; Breining, Ralf: Projection Technology Applications in Industry Theses for the Design and Use of the current Tools. In: Proceedings of the 3rd International Immersive Projection Technology Workshop. Stuttgart 10/11 May 1999. Virtual Prototyping State of the Art in Product Design Page 5 of 5