OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
Figure 1 shows the user interacting with a virtual model through a haptic device. The haptic sense is usually
divided into two main distinct sensory modalities. The first sense is the kinaesthetic sense (motion and force
sensing), which includes perception of muscular effort. The second sense is the tactile sense, which provides
coetaneous information, related to contact between the skin of the human body and the external environment
(pressure, vibration, temperature etc.). These sensory interactions enable the user to perceive physical properties
such as rigidity of the model and the surface characteristics of model (roughness etc.).
The evaluation of the design is required to make a decision on whether to discontinue the concept, further iterate
the concept, or start utilising the concept. Similarly, the end users can be involved to gauge the customer
satisfaction for the given concept. Another goal may be to evaluate the design from a human factors perspective.
The VR allows an industrial designer to sculpt and validate the concept design. A group of users can also evaluate
the concept in VR environment.
Virtual reality environment can provide real-time interaction with virtual world through several communication
methodologies. These include visual (preferably stereoscopic display), tactile (force feedback) and audio (stereo
sound) feedback. Virtual reality environment is used to provide a far more natural environment to the user than
that is possible by workstations. This is especially suitable for free form shape design. An industrial designer or
engineer can explore all conceivable options without the constraints imposed by commercial CAD/CAM
environments. However VR faces many issues in efficient use of the virtual reality environment. Firstly, the realtime
rendering of the complex word during simulation requires very large computations which are still not
feasible, particularly on desktop computers. The speed with which the computer processing speed is increasing,
will make is possible in future.
The second issue is in the implementation of collision detection algorithms. Collision detection, while interacting
with large, complex and deformable models can be very tricky. Many techniques are being used to develop
efficient collision detection algorithms. The third issue is of providing physical properties to the virtual models
created in virtual reality. To simulate the behavior of a real object, the simulation must include object properties
such as rigidity, strength, mass, friction, surface texture, and heat transfer. Adding these physical characteristics to
virtual objects require powerful computing hardware and efficient algorithms. This issue is of more importance
when we need to evaluate the product at the concept stage.
However, virtual reality development is a fast growing area in computer graphics and engineering. Already, it is
being used for training for laparoscopic surgery and games. This paper discusses the process of evaluation and
user training during the concept design in the virtual reality environment.
1.1. Previous Work
Virtual reality environment allows a user to use his/her sense of touch while interacting with a virtual model using
haptic devices. A user interacts with a virtual model by feeding and receiving information through tactile
sensation.
Different types of surfaces are used to represent virtual objects. The most common approach is to use implicit
geometry techniques to represent clay-like objects used by Bloomenthal and Shoemaker [5] and Witkin et al. [6].
Knopf and Sangole [7] investigated the Self Organization Feature Map (SOFM) as the starting point for haptic
interaction. The SOFM technique has also been extended for many applications. These include, geometric and
visual exploration of numerical data [8] and surface fitting [9]. Raviv and Elber [10] used a set of uniform
trivariate B-spline functions to represent virtual objects. On the other hand, Pungotra[11] used B-spline surfaces
to model objects in virtual reality environment for easy exchange with existing CAD software. Alternative data
structure to represent virtual sculpting has also be proposed such as, voxel-based system [12], and B-spline
surfaces [13].
Initially, the product models were created in existing 3D CAD systems and then translated into a VR
environment. These VR-enhanced 3D visualization techniques were used in Virtual Design II [14], and ISAAC
[15]. Such systems only permit designers to visualize and analyze CAD objects in a 3D virtual environment. A
VR-based CAD modeling environment that allows rapid shape creation by using a bi-modal, voice, and hand
tracking interface is the COnceptual VIRtual Design System (COVIRDS)[16, 17]. Mouse/keyboard interface is
replaced with voice recognition and 3D interaction devices and allows parametric and free form design modes. In
addition to COVIRDS, there are many VR-based design systems. These include 3DM [18], CUP [19],
DesignSpace [20], CDS [21], Loughborough University Conceptual Interactive Design (LUCID)and 3-Draw
[22]. LUCID [3, 23] integrated VR-based Human-Computer Interfaces into the design process. These models
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