Vision system inspects
heads-up displays for
To perform a final inspection on assembled head-up displays (HUDs), an automated
vision system is used detect the presence of screws, bolts and covers.
Heads-up Displays (HUDs) for the latest generation jet fghters encase advanced optical components within precision machined aluminium
castings. At a leading UK manufacturer, these
specialized units are designed, manufactured,
assembled and calibrated by highly skilled technicians. Due to the number of operations required in this process, fnal inspection is mandatory to ensure that all the assembly tasks have
been completed before the unit is shipped to the
customer for integration into the aircraft.
To automate this fnal inspection process,
Industrial Vision Systems Limited (IVS; Kingston Bagpuize, Oxfordshire, England (www.
industrialvision.co.uk) has developed a vision-based system that eliminates any human error
associated with this task (Figure 1). In developing the system, a major goal was to provide
a standardized inspection that
provides objective results with
minimal operator input.
Vision inspection tasks were
split into two categories: simple
surface level inspections such
as the presence of various screws,
bolts or covers, and more intri-
cate inspections that require pre-
cise lighting and camera setups
to determine pass/fail criteria.
The challenge posed by the
simpler inspections was not
the diffculty of assessing the
image against a pass/fail crite-
rion, but the number and vari-
ety of inspections that needed to
be performed across the six sur-
faces of the HUD unit. This was
achieved by splitting the inspec-
tion process into two parts. The
frst part required the operator
to place the HUD upside down
into a nest to allow three of the faces to be
To perform inspection of
the HUD, the system incorporates a gantry of cameras mounted on a linear drive
that move in the z axis (Figure
2). The laser projection unit
is mounted in-line with the
camera to allow a single laser line to be pro-
jected into the machined holes on the HUD.
In addition, white LED lighting arrays were
mounted above the camera to provide overall
diffused lighting for surface inspection checks.
The nest was mounted on two linear drives
allowing it to travel in both the x and y axes.
Using this setup, any point on the three inspec-
tion faces could be presented to a camera and
Mark Smith, Indus-
trial Vision Systems Ltd
(IVS; Kingston Bagpuize,
Oxfordshire, UK (www.
Figure 1: Industrial Vision Systems has developed a vision-based system that inspects head-up displays (HUDs) for presence of screws, bolts or covers and verifes that helicoils are
properly placed in the machined aluminium castings.