Simulation and Animation of Design Workplace and Models by ... - Tuke

Simulation and Animation of Design Workplace and Models by Motion Capture Technology Veronika Fecova, Jozef Novak-Marcinčin Abstract In today's advanced time people often need to simulate some natural events such as people walking or moving some things from one place to another. This article is focused on the kind of virual reality – MoCap – motion capture. Motion capture or motion tracking are terms used for describing the process of the recording of movements of user and the interpretation of these movements into the movements of digital model. Currently the most companies try to prepare the projects of new products and manufactories by simulations and analysis and not on assumptions or conjecture. At the beginning the workplace is modelled and different conditions is simulated before its real building. Result of this simulation by VR is workplaces too, which make provision for ergonomic requirements, because the bad designed workplace increases additional costs and assembling time. Keywords: simulation, virtual reality, motion tracking, optical system, passive target

1 Introduction In today's advanced time people often need to simulate some natural events such as people walking or moving some things from one place to another. Virtual reality (VR) is simulation of the real or fictive environment which can be visual sensed to the all dimension of space: height, width and depth. Its perfection depends on the advance of used devices as a head-mounted display, data gloves or data suits. This article is focused on the kind of virtual reality MoCap - motion capture. Motion capture or motion tracking are terms used for describing the process of the recording of movements of user and the interpretation of these movements into the movements of digital model. Currently the most companies try to prepare the projects of new products and manufactories by simulations and analysis and not on assumptions or conjecture. At the beginning the workplace is modelled and different conditions is simulated before its real building. Personnel are moving among virtual machines and monitor their location. In the case of a new idea, plan is reconditioned and the user is moving to the new area again. If the manufactory is optimally designed, then realization its building starts. VR has in these stages very important role, because there are a large financial savings. The manual assembling is simulated and ergonomically aspects too, for example whether the worker will have enough space for the hands and assembled components and whether he will have a good view for the job (Fig. 1). Result of this simulation by VR is workplaces too, which make provision for ergonomic requirements. From ergonomic aspect, the bad designed workplace increases additional costs and assembling time, for example tiredness of workers a subsequently for sickness from work are increased, the fluctuation of workers and so costs for training of new wor-kers.

get. This system can be passive or active. In active system, the signal transmitter often consists of the set of infrared LEDs and sensors are the cameras that can record emitted infrared light. The record of the camera monitors signals and sends information to the system processing unit. The unit makes extrapolate data to determine the position and orientation of the target. In this article, the ARTtrack2 system is described (Fig. 2). It is passive system.

Fig. 1 VR in assembly process of car

2 Optical MOCAP - ARTtrack2 Optical motion tracking devices use light. Using this light the system can measure the position and orientation of target. Disadvantages of the system are these, that in view between the camera and the target can be influence of ambient light or infrared radiation and this may cause a lower efficiency of the system. Optical motion tracking devices use light for measuring the position and orientation of tar-

Fig. 2 Principle of passive targets

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This system uses passive rigid-body targets (Fig. 3). These markers are backreflecting the incoming IR radiation into the direction of the incoming light. These markers are mostly spheres covered with retro reflecting foils, but can also be stickers made from retro reflecting material. This passive system do not requires wear wires or electronic devices from user. Markers are usually attached directly to the user and for head tracking in passive stereo systems, tracking targets must be fixed to the stereo glasses and other targets are attached directly to the user (Fig. 4). At least two, maximum 16 tracking cameras are needed for this system. A.R.T. tracking cameras are equipped with CCD image sensors, working in the near infrared light spectrum. An infrared light flash is not visible for the hu-man eyes. The ARTtrack2 IR-camera is a good solution for distances up to 4 meters. The maximum frame rate is 60 Hz. Cameras have built in IR LED flash, wavelength 880nm. The calibration of targets is very fast and simply. The identification of a rigid body is based on the distances between single markers in a target (Fig. 3). This means, each target has to show a unique set of marker distances.

Fig. 3 Target with passive markers

Fig. 5 Virtools

4 Simulation of machine´s location On the beginning of starting of this system, the calibration is needed (Fig. 6). Then, the “walking” in virtual production hall is possible. When the user stands on the place, where the calibration was, in the virtual hall stands too and subsequently, into which the direction the user is moving, so in the virtual world he is moving in the same direction. When the user is near to the calibration position, his speed of walking in the virtual world is slow and when he is further, his speed is faster (Fig. 7). So the user can try some properties of new designed hall, for example location of machines and he can try, whether will have enough place for the crossing among machine with a material. After the trying to walking in virtual production hall, when only the target attached on the glasses was used, the other targets on the user can be used. The process is the same as in the walking. At the beginning the calibration of marks is needed and subsequently is possible to control the movements of the hands of the virtual worker. The using of this technology allows to try arm´s reach of the worker, so to see whether the location of the components required for assembly of the kit is within reach of the worker's hands (Fig. 6.).

Fig. 4 Passive targets attached on the user

3 Virtools One of more software used for 3D visualization is Virtools (Fig. 5). Virtools is the software for 3D visualizetion. It is an application which allows quickly and easily creating virtual world. The creating of models in Virtools is not possible, but simple elements such as cameras, lights, rooms and standard media such as images, sounds, animations and models can be created with the click of an icon in Virtools Resources. It is simply software, which uses the creating of graphics script about behaviours of components from virtual world. It is more easily for user like using text script. This software consists from 3 parts (Fig. 5). The top left window is the 3D Layout window, used to visualize project in real-time. The top right window is Building Blocks and Virtools Resources and down of screen is Level Manager and Schematic windows, used for organizing project and creating scripts.

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Fig. 6 Calibration process

6 Conclusions

Fig. 7 Walking in the virtual production hall

Fig. 8 The controlling of worker´s hands

5 Animation of models in production hall The script for animation of robot is on the Fig. 9. The orders “Bezier Progression” and “Rotate” was used for the creating of this script. It is very simply script. On the start the “Key Waiter” is set. The “Bezier Progresion” interpolates a float according to a 2D Bezier curve in the [Min, Max] range, in a given number of milliseconds. In the parameter of “Translate” the 3D target is set and “Multiplication” is added parameter operation, which defines the vector for moving. The right function of model, the right setting of hierarchy is very important. All parts need to have right parents and all parents need to have right children.

Fig. 9 Script for animation of robot Animation of robot is shown on the Fig. 10. This robot takes some part from crate and put this part on the conveyor.

Fig. 10 Animation of robot

In this time, virtual reality technology is most used in the automotive and aerospace industries. If the whole process of design of product is designed, controlled and simulated with help of virtual reality, in the manufacturing process should no bigger problems. With this system user can try to walk in the virtual production hall a can see, that the space among machines is enough big for workers and for cross over with material among these machines. This system tracks the user´s movements and subsequently the virtual worker performs same movements like user, too. It can try arm´s reach of worker, whether the assembly can be assembled and to test, that the worker will have enough space and in which position will be his body. It is important, because subsequent health problems cause the labour turnover and new training for them is not very convenient for the company. With the help of these applications the company can try these conditions and so they can save their money. Fecova Veronika, M.Sc., Prof. Novak-Marcincin Jozef, M.Sc., PhD., Technical University of Kosice Faculty of Manufacturing Technologies Presov Street Sturova 31, 080 01 Prešov Phone: 051/ 7722603, Fax: 051/ 77 33 453 E-mail: [email protected], [email protected]

References [1] Burdea, G. C., Coiffet, P.: Virtual Reality Technology. Second Edition. New Yersey: John Wiley&Sons, Inc., 2003. 424 s. ISBN 0-471-36089-9. [2] Cotetiu, R. I., Kuric, I. – Novák-Marcinčin, J. Ungureanu, N.-S.: New Trends in Mechanical Design and Technologies. Cluj-Napoca: Editura, 2005. 224 s. ISBN 973-751-084-4. [3] Fečová, V.: Optical motion tracking used in the virtual reality systems. In: CEURSIS 2010: the International Conference of the Carpathian Euroregion Specialists in Industrial Systems, Baia Mare, 2010, p. 81-86, ISBN 978-606-536-094-5. [4] Fečová, V.: The principle of the active and passive markers of optical motion tracking for the virtual reality systems, In: New Ways in Manufacturing Technologies 2010: 10th international scientific conference, Prešov, Slovakia. Prešov : FVT TU, 2010, p. 145-152, ISBN 978-80-553-0441-0. [5] Havrila, M.: Trends in computer design of production systems. In: Manufacturing Engineering/Výrobné inžinierstvo, 1/2009, p. 88-91, ISSN 1335-7972. http://web.tuke.sk/fvtpo/journal/index.htm [6] Havrila, M.: Tendency of Production Systems Computer Simulation Development. In: Manufacturing Engineering/Výrobné inžinierstvo, 3/2008, p. 21-23, ISSN 1335-7972. http://web.tuke.sk/fvtpo/journal/index.htm [7] Kočiško, M., Janák, M.: Creation Method of Visual Disassembly Procedure. Journal CA Systems in Production Planning, Vol. 9, No. 1, 2008, pp. 37-39, ISSN 1335-3799. To be continued on page 50

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