1 research outputs found
Absolute multilateration between spheres
Environmental effects typically limit the accuracy of large scale coordinate measurements in
applications such as aircraft production and particle accelerator alignment. This paper presents
an initial design for a novel measurement technique with analysis and simulation showing that
that it could overcome the environmental limitations to provide a step change in large scale
coordinate measurement accuracy. Referred to as absolute multilateration between spheres
(AMS), it involves using absolute distance interferometry to directly measure the distances
between pairs of plain steel spheres. A large portion of each sphere remains accessible as
a reference datum, while the laser path can be shielded from environmental disturbances.
As a single scale bar this can provide accurate scale information to be used for instrument
verification or network measurement scaling. Since spheres can be simultaneously measured
from multiple directions, it also allows highly accurate multilateration-based coordinate
measurements to act as a large scale datum structure for localized measurements, or to be
integrated within assembly tooling, coordinate measurement machines or robotic machinery.
Analysis and simulation show that AMS can be self-aligned to achieve a theoretical combined
standard uncertainty for the independent uncertainties of an individual 1 m scale bar of
approximately 0.49 µm. It is also shown that combined with a 1 µm m−1
standard uncertainty
in the central reference system this could result in coordinate standard uncertainty magnitudes
of 42 µm over a slender 1 m by 20 m network. This would be a sufficient step change in
accuracy to enable next generation aerospace structures with natural laminar flow and part-topart
interchangeability