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How DaimlerChrysler is interfacing the real and the unreal VIRTUAL REALITIES Virtual Reality is being used more and more to not only design vehicles but to find the possible pitfalls in manufacture and minimise assembly time and costs. DaimlerChrysler has built a specialist VR facility in Ulm, Germany, where designers and engineers use VR tools to make their work more efficient. 12  Silicon Chip T he Virtual Reality Cometence Centre (VRCC) makes VR tools available to developers at their workstations. Depending on the task at hand, employees can select the required degree of immersion in the visual world they wish to enter. Not only that, they can mix “real” and “virtual” worlds! State-of-the-art facilities at Ulm include:  a PC-operated holobench;  a holostage, a new semi-circular projection which has recently been successfully patented;  a fully-equipped mixed and augmented reality laboratory. Holobench – the technology The holobench, a virtual workbench, comprises a vertical and a horizontal surface onto which projectors display images from behind and from below. The holobench in Ulm is the first of its kind in the world to be operated using “Infitec technology”, which enables stereo-vision through the separate control of the left and right eyes using interference filter technology. The result is a bright, three-dimensional image. It also uses DLP projectors, which give much greater luminous intensity than do tube projectors. The computer filters out the ambient light in the room so that the user can work on the holobench in daylight rather than in a dimmed setting. The VRCC holobench is operated by four PCs, with two more functioning as servers. The latter also carry out collision calculations and determining the position of the user. Research on the virtual workbench Long before the first physical model of a newly developed product is tested, designers need to know whether the individual components can be installed easily and cost-effectively. Such construction feasibility studies can now be simulated to a great extent on the holobench. The engineer puts on a data glove with sensors that measure the movewww.siliconchip.com.au ments of his or her hand. A corresponding virtual hand, which can install or remove virtual components, appears on the holobench surface. Sensors calculate the exact position of the hand in the virtual space. If the electronic hand touches any components, it does not move on any further but a wire-grid hand passes through the part and the point of collision is highlighted in color. As an example of the many investigations the VRCC has carried out, they examined the removal of the alternator from the Chrysler PT Cruiser. The research revealed that in order to remove the alternator quickly and easily, it was necessary to move another component by just a few centimetres. The practical aspect in investigations like this one is that the computer “feels” when contact takes place with another component, even in places where the point of contact is obscured by the image of the component. The software makes the components behave “realistically” by simulating their physical and dynamic properties. This means they can even slip along obstacles, altering their position in the space. In the past, it was only possible to research rigid objects in installation and removal studies. Now, however, DBView — visualisation software developed by DaimlerChrysler — is able www.siliconchip.com.au to automatically calculate the amount of space required for flexible objects such as cables or tubing. One example is vehicle seating that has four different axes of movement. Each variant means that a different amount of space is available in the vehicle. The data comes directly from the CATIA construction system onto the holobench surface. Whereas it was previously only possible to visualise the components, they can now also be altered directly and in real-time. When the collision detection system is in operation, the relevant components are marked – or the virtual seat adjustment does not function to the intended degree. Even a complicated mechanism, such as a moveable steering column, can be manipulated to estimate its behavior when construction alterations are made. Engineers are particularly interested in how much space the steering column can take up in extreme situations. DBView can make this calculation. Another typical use of the holobench is the interactive simulation of deep-drawing processes. The settings of the virtual equipment are controlled via a three-dimensional menu, which is operated by a so-called flying mouse. The sheet metal thickness is represented by different colors before, during and after processing. It is thereby easier to check the stresses acting on the metal sheet during the stamping process. Semi-circular projection + CAVE = HoloStage The VRCC has combined the advantages of semi-circular projection with the advantage of the CAVE. This is a room where the floor can also be used as a projection surface but where only one person has good-quality 3D vision. A semi-circular floor was built into the semi-circular projection area. Projection onto the floor is by means of two projectors and mirrors on the ceiling. The result is a stereo-capable holostage, which was recently successfully registered as a patent. Another feature of the holostage is the tracking system, which allows the observer to see an extremely realistic picture, depending on the angle. No cables or wires are necessary. Six cameras monitor the position of the user. The boundaries between the horizontal floor and the vertical, semi-circular wall are blurred by the computer, which “softly” masks the edges. The observer sees an edgeless, three-dimensional picture on the holostage. HoloStage – factory planning In factory planning it is just as important to consider the movements November 2001  13 people make, as is the correct positioning of the assembly line or the storage of materials. Researchers use a virtual model of a person, which moves around independently within the data field of the semi-circular projection. The starting and finishing positions of a particular route are already given but the number of steps taken or the movements made on the way are generated directly by the computer. Being able to represent or measure routes and distances is only one important factor in factory planning. Another is calculating stresses acting on the spine when an employee has to lift or install a component into a vehicle. These calculations, based on a large amount of medical data, are made on a virtual model to simulate real conditions. HoloStage – robot teaching VR technologies serve not only as output media (ie, to represent computer-generated data) but can also be used to input data. In the case of a robot that installs components or works on a car body in the semi-circular projection area, movements can be planned to the millimetre. To achieve this feat, the robot is taken by the hand, so to speak, by the engineer wearing a data glove. It is then led to the point where a component or tool is to be picked up and then to the point of contact with the vehicle. Carrying out robot teaching in this way is quicker and easier than entering the complex coordinates step-by-step on a computer. The information gained from using virtual models of humans for ergonom14  Silicon Chip ic studies, teaching robots and calculating likely component collisions on the assembly lines helps planners select the optimal factory layout. It is hardly possible to imagine modern, process-optimised factory planning without VR technologies today. Mixed reality/augmented reality The “Mixed-Reality Laboratory” at the VRCC is used to study applications in which it makes sense to combine elements from the real world with images from virtual reality. In this way, it is possible to teach company employees how to undertake complex manufacturing processes long before the launch of a new production series. The user wears a special head-mounted display fitted with a tiny video camera, which supplies images of what is actually happening. These video images are then exactly combined with a virtual image of the part or component under investigation. This perfect “fit” between the video images and the computer-generated image of the virtual component is made possible by the fact that all the real components have been given socalled markers. Markers consist of symbols or numbers on a flat surface, which are registered by the video camera and then transmitted to the computer. They tell the computer the precise angle at which the virtual image has to be positioned. In addition to this combination of images, the user is also provided with further information — in the form of text, graphics or video images — on how to install a component. This might include information on which tool should be used, as well as where to start. It is also conceivable that live images of an instructor could be superimposed. The new technology also has numerous applications in the fields of maintenance, vehicle diagnostics and service. For example, a mechanic is faced with a defect. Equipped with a semi-transparent head-mounted display, he or she is provided with the relevant information about the state of the vehicle. To guide the mechanic, an instructor establishes the precise nature of the problem through a natural language dialog. Images, graphics or arrows pointing to specific vehicle components indicate where the problem might lie. Even in a normal workshop situation, the use of mixed and augmented reality could help combine the usual toing-and-froing between reading the manual and actually working on the vehicle into a single activity and, as such, help cut repair times. Such a system would be particularly www.siliconchip.com.au attractive in remote regions where the workshop may not have a lot of experience on a particular make or model. In such a case, the mechanic or even the driver would be able to obtain direct advice on the nature of the problem. Mobile VR To increase the flexibility of maintenance and inspection routines for large fleets of vehicles, VR technology is also set to become increasingly mobile. A portable video unit strapped to an engineer’s belt will be able to transmit images to the computer. Once there, virtual reality images will be integrated and then sent back to the engineer’s head-mounted display. In such a context, the navigation aids — including hints about the source of the problem or tips on how it could be remedied — are once again set to play a major role. Text information could be superimposed on the images at the appropriate point. Such procedures are likely to result in substantial time savings as well a considerable improvement in quality. On the one hand, there will no longer be any need to consult technical manuals and on the other, the quality of the work can be checked as it occurs. Cockpit ergonomics Although virtual reality can be seen, it cannot be touched or felt. In certain situations, it makes sense to use relatively simple elements in order to create real mock-ups containing all the basic physical components that the user needs to establish a tactile contact with reality. As soon as it is possible to harmonise the virtual and the real worlds in this way, the user is able not only to see objects but also to “grasp” them – ie, touch and manipulate them. As a result, immersion in the world of virtual reality is made all the more realistic. Another task at the VRCC is to examine various vehicle cockpit designs from an ergonomic point of view. This is also an example of what is known as collaborative rapid prototyping. Here, the designer and user work hand in hand. The user sits in a wooden cockpit mock-up, containing instruments positioned according to the designer’s specifications (who sits close by). Via a head-mounted display, the user is supplied with images of both the planned cockpit and the road or www.siliconchip.com.au landscape through which the vehicle is virtually travelling – similar to an aircraft simulator. At the same time, the user can also try out the various arrangements of cockpit instrumentation and displays. With the aid of a data glove, the controls can be moved around or reformed into a different shape. The wooden surface of the cockpit mock-up provides the user with the necessary tactile sensations. The designer is also able to make immediate changes to the cockpit layout during the testing process. As a result, optimal cockpit ergonomics can be achieved more quickly and efficiently. Flow visualisation CAD models are made up of an agglomeration of surfaces. However, the process of vehicle design also makes substantial use of aerodynamic flow data and the flow of air inside the vehicle cockpit. As a rule, flow data is three-dimensional. Here, the complex challenge facing the VRCC researchers was to combine flow data with surface data in one single representation. The idea was to be able to see the effect of various flow patterns, the data for which had been processed in advance by mainframe computers working in overnight shifts. This visualised flow data is mixed with “real” images superimposed via video as well as VR data relating to the vehicle interior. In this way, various design alternatives can be tested. This might involve the impact that the size and shape of headrests have on the supply of fresh air to rear-seat passengers or the effect that the shape and settings of the air vents have on temperature control in the vehicle. VR meetings If VR truly is the intuitive, fully immersive man-machine interface of the future, then it certainly makes sense to extend its scope beyond the current dialog between engineer and computer. In the future, the aim is to use VR in a group context. All the information relevant to product development must be made available over and beyond system and even company boundaries. Indeed, such availability must function along the entire length of the chain. In this way, virtual reality could well help bring the twin processes of product planning and product development together even more. For a graphic example as to what the VRCC researchers have in mind for this exciting new technology, consider the following scenario: Designers and engineers seated around a conference table are discussing the latest version of a component under development. Each person is wearing a special head-mounted display. In the middle of the conference table is a turntable marked with a range of symbols. Each participant sees a virtual image of the component from exactly the same perspective as he or she would were it a real visual experience. The 3D model can therefore be fully visualised, with participants able to discuss the latest stage of component development. Participants do not even need to be in the same room, or even the same country. SC Acknowledgement: Text and photos courtesy of DaimlerChrysler. November 2001  15