Question

What is the difference and associated benefits between virtual design (VR) and rapid prototyping (RP)?

Answer 1

Virtual Design

1) Definition-

A virtual reality system provides a platform for computer generated images to interact with the user. As the user reacts to these images, requiring to change the scene in some way, so the computer complies. The images, along with other possible external stimuli show objects that combine together to form virtual worlds. Perhaps the best definition offered yet on the exact nature of VR comes from Zeiter -- A virtual reality interface system must offer a degree of 3 key components:-

- Autonomy: objects must react to external stimuli, have collision boundaries and exhibit real world effects (e.g., coefficients of restitution, gravity, and friction).

- Interaction: one must be able to manipulate the parameters of each object in real time.

- Presence: a crude measure of the fidelity of the viewing system

2) VR is cheaper and less technical to use than rapid prototyping.

3) The turnaround of ideas is much faster with VR and therefore this technology is likely to benefit the aesthetic designer more than the design engineer.

4) VR provides a complimentary technology to rapid prototyping, but the interface is most suitably accommodated through CAD.

Rapid Prototyping

1) Definition-

Rapid prototyping technology focuses on reducing the lead times and costs associated with new product development . As a new product is introduced, or as products are updated, various aesthetic and functional designs and tests take place. Somewhere during this process, a physical model is evaluated. Using conventional processes and highly skilled artisans, the construction of this single model can take many days.

Rapid prototyping systems are capable of making highly accurate models, or prototypes, in a very short time. The starting point for such systems is a good quality 3D CAD system. Solid models are constructed using the CAD system and then postprocessed in a layer format to make them suitable for the prototyping machines. Models made in this way are therefore limited only by the scope of the CAD system and the resolution and dimensions of the prototyping system. Models can therefore exhibit very complex geometries indeed.

2) RP is expensive and more technical to use than Virtual Design.

3) The turnaround of ideas is much slower with RP and therefore this technology is not likely to benefit the aesthetic designer more than the design engineer

4) RP does not provides a complimentary technology to virtual design, and the interface is not suitably accomodates through CAD.

Associated benefits

When stage is reached where quantitative test data is required then physical prototyping becomes necessary. Rapid prototyping systems shorten this process dramatically making it possible to recoup a significant capital investment in a short period. The operation of these machines is still significantly long. Generally parts are in a finished, useable state in around 2 days. If all that the part is required for is to assess factors like dimensional fit, accessibility, optimal position, aesthetics, then a system that operates in real time is much more appropriate.

The.primary use for rapid prototyping systems is not therefore in qualitative assessment phase of product development. Manufacturers are realising this, and much more use is being made of soft tooling processes (like investment casting) to produce test parts and for short production runs. This is a much more important role for this technology to fill. Competitive marketing policies still dictate that physical models be created for purposes like tendering and user evaluation. VR, with its capacity to model real life provides a practical replacement for rapid prototyping in this sense. VR has the potential to fulfil at least some part of the first 4 uses for rapid prototyping described by Jacobs those of visualization, verification, iteration and optimization. There is no possibility of VR fulfilling the 5th use, that of fabrication. With VR supporting, the more expensive rapid prototyping technology can therefore be considered free to perform the more production related tasks.