From: John.Wilson@nottingham.ac.uk (Prof John Wilson)
Subject: APPS: Virtual metrology - any research?
Date: 19 Feb 1997 10:24:43 GMT
Message-ID: <5eekdb$p6h@paperboy.ccc.nottingham.ac.uk>
Organization: University of Nottingham


One of my colleagues in the Engineering Faculty here wishes to set up
a joint research project with VIRART (the Virtual Reality Applications
Research Team). In the first instance he has asked me to post the
brief request for contacts below.  Please reply to me.  Thank you.

Virtual Metrology

This concept involves using VR technology to shrink and scale the
observers viewpoint until minor deviations from nominal are easily
perceived, visualised, and assessed using representations of tolerance
limits, and virtual instruments.  This will be useful because at
present it is very difficult to understand the interactions between
complex components and tolerance limits on a micro-scale.  For
example, the interaction between actual linear dimension and
geometrical form for two mating parts will potentially cause point or
line contact instead of the desired surface contact.  This could
result in rapid wear or premature failure.  The ability to examine the
type of contact, and assess the gaps between components will assist
designers and manufacturing engineers achieve better quality of design
and manufacture.  The interaction between surface finish properties
and surface geometry is also important, and the potential to combine
information on these characteristics would be valuable.

Various techniques for examination and interaction are of interest,
particularly fly-through, 3D interaction, collision detection and
assembly sequences.  A pre-requisite for Virtual Metrology is the
ability to import component information from precision measurement
instruments such as Coordinate Measuring Machines, roundness and
surface finish measuring instruments, as well as from CAD systems.
Many CAD systems do not represent tolerances effectively as part of
the component model, and methods to add tolerance limits to the
component model will require investigation.  Virtual instruments will
need to be designed that act as analogues of the familiar manual
instruments and allow the collection of dimensional information.

A beta version of the Silicon Graphics Cosmo Player, a VRML (Virtual
Reality Meta-language) plug-in to Netscape, has been obtained as has a
useful freeware converter from various graphical and CAD output
formats to VRML.  These have allowed the use of Netscape on the PC to
examine and fly-though CAD drawings.  The initial investigation has
immediately exposed rendering weaknesses with VRML, Cosmo Player,
Netscape and/or the file converter.  More effective
engineering-oriented software tools will be required for a more
serious project, starting with the Division, Elysium and Superscape
systems available at VIRART.

In the meantime, if anyone knows of similar work going on elsewhere we would 
be grateful to hear about it.

John.Wilson@nottingham.ac.uk (Prof John Wilson)