Note: Descriptions are shown in the official language in which they were submitted.
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VIEWING APPARATUS
The present invention relates to viewing apparatus and in particular, but not
exclusively, to viewing apparatus for examination of a cow's teats.
Published international application WO 96/24084 discloses examples of a
viewing
apparatus operative to transpose the views of an object seen from a number of
different
viewpoints into a single two-dimensional representation.
The principal advantage of taking multiple viewpoints around an object is that
the
off axis distortion when transferring a viewed object to a single plane is
reduced as the
number of radial viewpoints increases. This is important as a minimum feature
on the
surface of the object may otherwise not be resolved to its full extent.
According to the present invention, viewing apparatus operative to transpose
the
views of an object or object part seen from a number of different viewpoints
into a single
two-dimensional representation comprises a support structure to which is
secured a
plurality of reflectors disposed about a viewing space in the apparatus, one
or more cameras
or other detection devices disposed to receive optical information from the
object or object
part in the viewing space by light reflected from the reflectors, and
placement means
adapted to move the support structure to and from a position in which the
object or object
part is contained within said viewing space.
Where the apparatus is to be used to inspect a cow's teat for cleanliness and
contamination by dirt, faeces or other contaminants, artificial illumination
is preferred to
give consistency of results, for example, by one or more light sources placed
around the
periphery of the viewing space, with minimum obstruction of the optical paths.
A
convenient light source for this purpose could, for example, comprise a light
guide
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encircling the viewing space and illuminated by one or more light emitting
diodes or
filament lamps for example.
As an alternative, illumination could be provided by use of a beam-splitting
combiner located between the reflectors and the detection devices) so that
light from the
or each light source is directed to the teat using the same reflective
elements as the reflected
light that is returned to the detection device(s).
In this alternative system, the component of source light that passes through
the
beam splitting combiner is held in an optical trap, for example a cavity
having a highly
absorbent coating applied to the internal surface of the cavity.
Conveniently, examination of the teat or other object contained within the
viewing
space of the apparatus may be enhanced by means illuminating the object with
different
optical wavebands and measuring them independently, for example, using one or
more
beam-splitters to split the returned light into different paths.
Conveniently, the illumination means includes a broad band light source
operating
over a wide wavelength range. The detection devices may then incorporate
interference
filters to take independent information in different optical wavebands.
Alternatively, the
illumination means may include some means of varying the wavelength of a
single light
source to provide different detection parameters; for example, the
introduction of
interference filters at the source will allow the detection device again to
take independent
information in different optical wavebands. As a further alternative, two
different light
sources, e.g. laser sources, operating at different wavelengths could be used.
Where a camera is used as the or each detection device, the type of camera
selected
and the background lighting required for detection of teat lesions, for
example, might also
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be used to measure the colour of the teat such that any abnormal swelling or
dimensional
change could be assessed in conjunction with a colour change such as reddening
of the teat.
Indeed it can be shown that certain diseases exhibit particular optical
reflectances, so it
may be possible to detect and quantify these disease types over the surface of
the teat.
Where there is a need to distinguish scars from open and scabbed wounds on the
teat, this can best be done perhaps by use of illumination at a specific
wavelength as the
shape of the wound will not be different in these two cases. It is to be
noted, in this respect
that healed teat lesions appear to be very light in colour in relation to open
wounds.
Similarly. one could also look for blood related wavelengths to detect open
wounds.
Further information on these and related topics may be had by reference to
published patent
applications WO 92/19098, WO 94/12019, WO 94/12020 and WO 94/12022.
Where a filter is fitted so that light at a particular wavelength (for
example, infra
red) may be used for illumination or detection purposes, then subcutaneous
inspection and
assessment of diseased teats is possible whilst any infection is sub-clinical,
i.e. before it
would normally be visually apparent to the stockman on the surface of the
teat. A different
filter might be used to give a wavelength that could be used to detect
chlorophyll, for
example.
It is to be noted that inspection can be conducted using light that is either
reflected
or emitted from the object being examined, i.e. the teat. The light may be in
the infra red,
visible and ultraviolet range if broad band sources are used for illumination.
It should further also be noted that it is possible to use illumination to
cause features
on the teat to fluoresce, e.g. chlorophyll or injury, and in this respect,
illumination at
specific wavelengths other than in the infra red range could be an important
practical
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option.
Using historic information on the teat size together with a predictive
algorithm as
to how the size of the teat might change between milkings or during the
natural cycle of
lactation in a dairy cow, the apparatus could be used to detect an
inflammation or swelling
of the teat due to health problems.
In use of one embodiment of the invention, with the automatic milking robot of
British Patent 2258382, the support structure for the reflectors is mounted at
the distal end
of the same "wrist action" sub-assembly as is the teat cup holder. In this
case. where the
said sub-assembly or "robot arm" is acting as the placement means of the
present invention.
both the teat cup holder and the detector could pivot about the same inclined
"wrist" axis
in such a way that the robot arm would locate the teat initially and apply the
support
structure over the teat whilst the teat cup holder carries the teat cup still
in the inverted
position. After the inspection stage and assuming the teat is deemed to be
both clean and
healthy, the entire head could then pivot about the wrist axis of the robot
and the robot arm
would then drive the now correctly orientated teat cup, onto the teat.
The one or more detection devices may also be secured to the support structure
so
as to move with the reflectors during the introduction and removal of the
object or object
part in the viewing space. Alternatively, the detection devices) may be
mounted
independently of said structure.
Conveniently, in this last case, the light from the reflectors could be
transmitted
down the robot arm using coherent fibre optic bundles, say, to a camera or
other detector
located externally of the arm. The advantage of this would be to remove the
camera-
associated electronics, which might be prone to damage or water ingress during
a cleaning
cycle, from the distal end of the robot arni. Care would have to be taken,
however, to avoid
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problems associated with the_twisting action on the fibre optic bundle by the
pivotal head.
As already mentioned, the detection devices) could comprise one or more
cameras.
The images that the camera (or combination of cameras) produces may be
processed to provide information on contamination areas on the teat, diseases
including
warts and disorders at the teat apex.
Suitable miniaturised imaging cameras for this purpose might be those
currently
available from Vision plc, possibly encapsulated against moisture ingress.
Such cameras
operate at a relatively low voltage {typically 5 volts) and could be used
quite safely even
in the presence of moisture, provided they axe adequately sealed.
Conveniently, where the apparatus is intended for use in teat examination,
steps
should also be taken to ensure that both the camera and any object-
illuminating lighting
system are kept clean either during the inspection cycle, or cleaned between
cycles. Thus,
provision could be made, for example, for the detection devices) to activate a
cleaning
mechanism (perhaps similar to the ones described in British Patent 2272627).
There could
also be provision for washing the apparatus e.g. using a continuous or
intermittent water
wash and air dry curtain as is current practice in electro-optical sorting
machines for
agricultural produce.
In preferred embodiments of the invention, the viewing space lies along an
axis of
the apparatus and at least some of the reflectors are disposed radially about
said axis so as
to surround an object or object part contained in the viewing space.
Additionally, or alternatively, one or more of the reflectors may be axially
spaced
from the viewing space so as to provide an end view of an object or object
part contained
in the viewing space.
Conveniently, the reflectors consist of mirrors, although, in principle, other
means,
for example, prisms, could be used as an alternative.
Conveniently. the viewing apparatus of the present invention may be combined
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with an air sampling device such as the one disclosed in published
international patent
application WO 94/12022 to allow assessment of an animal's health and the
detection of
disease or defects on its udder. In such a combination, there may be scope for
combining
the signals from one or both the detection systems present and processing them
through a
predictive algorithm to give an overall assessment of the animal's health.
Embodiments of the invention will now be described, by way of example only,
with
reference to the accompanying drawings in which:
Figure 1 shows a simplified schematic perspective view of an apparatus
according
to the present invention;
Figure ? is a schematic horizontal section of the same apparatus; and
Figure 3 is a schematic side view of the apparatus looking from left to right
in
Figure 2.
With reference first to Figure 1 of the drawings, an apparatus 10 for viewing
a
cow's teats 1? comprises a support casing 14 housing a first array of five
minors 16
arranged about a vertical axis 18 of the apparatus.
For clarity, only rivo of these mirrors 16 are included in Figure 1. although
all five
are depicted in Figure 2 which is to scale as regards the relative
dispositions of the mirrors
and a camera '_'0. Light is reflected to this latter via an extension piece 22
which allows the
camera to be spaced some 30cm, say, from the axis 18.
At its top end, the casing 14 is provided with a 7cm diameter aperture 24
which
allows entry of the cow's teat into the hollow cylindrical viewing space 26.
The mirrors 16 provide five views, equally radially disposed about this
cylindrical
space.
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The mirrors are disposed in such a way as to modify the optical paths through
the
apparatus and to project the views to a single point at the camera 20 which is
connected to
a suitable peripheral electronic image-processing system (not shown) which
processes the
camera inputs to identify the features under investigation. Such systems are
well known
in related arts.
The projections are also made in such as way as to minimise cumulative angular
coverage from the single viewing point. This allows efficient use of a CCD-
type camera
detector to be positioned at this point to capture images of all the views
simultaneously.
The overall viewed area is a pentagon inscribed within the cylinder cross
section
of the viewing space.
The disposition of the camera detector is such that the variation in path
lengths to
each of the views is small compared with the mean length, therefore depth of
field and
geometrical scaling variations are minimised.
In the bottom section of the casing 14 are located two further mirrors 28
which lie
below and on opposite sides of the viewing space 26 and which are so inclined
as to
provide an end view of the teat 12.
Figure 3 diagrammatically illustrates the light paths from viewing mirrors 28
via
redirection mirrors 30 to the camera 20 at the end of the extension piece 22.
The minors 28 project two views at 45 degrees to the long axis of the teat.
This
allows visualisation of any apical distribution of contamination or defects.
The apparatus is completed by a light source 32, beam-splitter 34 and light-
trap 36.
In more detail. the light source comprises a mains-powered bulb-illuminator
38, for
example a halogen lamp, mounted in an apertured housing 40 connected to one
side of the
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extension piece 22 adjacent camera 20. The light trap 36 is secured on the
other side of
piece 22 to absorb any light which the beam-splitter 34 either fails to
reflect towards the
viewing space 26 or to pass from that space to the camera 20.
In an alternative embodiment of the invention (not shown), the camera 20 is
replaced by a series of cameras all viewing the same optical path and alI
having different
interference filters in the optical path for the scanning of a cow's teat
within the viewing
space 26. The filter selection is determined by previous measurement of
typical teat lesions
or defects by a scanning spectrometer.
If desired, additional reflectors or the like may be included to provide
optical
rearrangement of the various views prior to image capture at the camera(s).
Examples of
this technique may be had from application WO 96/24084.
In one investigation conducted with a spectrometer, the wavelength range
scanned
was from 600 to 1600 nm and the spectra created showed several things, viz:
(i) 30-40%
reflectance in the 600 to 700 range; (ii) in all cases a cusp in the
chlorophyll absorption
band 6~Onm (indicating faecal dirt); (iii) a large difference between healthy
tissue and
healing scab lesion; (iv) substantial difference between healthy tissue and
teat tip scab;
(v) substantial difference between healthy tissue and teats with warts (it is
to be noted in
this respect that the spectra were taken on the area of teats adjacent to the
warts present on
the teat and not actually on the warts themselves). Mastitis and other
diseases are
detectable using the same or related techniques.
_g_
