GB2325300A

GB2325300A - Viewing apparatus

Info

Publication number: GB2325300A
Application number: GB9709738A
Authority: GB
Inventors: Hugh Gerald Stirling
Original assignee: British Technology Group Ltd
Current assignee: BTG International Ltd
Priority date: 1997-05-14
Filing date: 1997-05-14
Publication date: 1998-11-18
Also published as: CA2288972A1; EP0981777A1; WO1998052087A1; GB9709738D0

Abstract

Apparatus operative to form a 2-D representation of a number of different views of a 3-D object, for example a cow's teat, comprises a support casing 14 housing an array of five mirrors 16 arranged about a vertical axis 18 of the apparatus. Light from a source 38 is reflected by a beam splitter 34 and is subsequently reflected by mirrors 16 onto an object within the viewing space. Light reflected by the object is returned via the mirrors and beam splitter to a camera 20 which may be separated from the apparatus using fibre optics. The support casing is movable to allow positioning of the object within the viewing space. Spectral analysis may be used to detect the presence of contamination or disease of the object. A plurality of cameras responsive to different wavebands and a broad band source, or a single camera and a plurality of narrow band sources may be used.

Description

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 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 device(s) 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 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 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 device(s) 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 cameraassociated electronics, which might be prone to damage or water ingress during a cleaning cycle, from the distal end of the robot arm. Care would have to be taken, however, to avoid problems associated with the twisting action on the fibre optic bundle by the pivotal head.

As already mentioned, the detection device(s) 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 are 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 device(s) 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 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 2 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 12 comprises a support casing 14 housing a first array of five mirrors 16 arranged about a vertical axis 18 of the apparatus.

For clarity, only two 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 20. 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.

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 mirrors 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 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 all 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 650nm (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.

Claims

1. 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 comprising 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.

2. Viewing apparatus as claimed in Claim 1 including one or more light sources to give artificial illumination of the object or object parts in the viewing space.

3. Viewing apparatus as claimed in Claim 2 in which the or each light source comprises a light guide encircling the viewing space and illuminated by one or more light emitting diodes or filament lamps or the like.

4. Viewing apparatus as claimed in Claim 2 in which illumination of the object or object part is provided by use of a beam-splitting combiner located between the reflectors and the detection device(s) 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).

5. Viewing apparatus as claimed in Claim 4 in which the component of source light that passes through the beam splitting combiner is held in an optical trap.

6. Viewing apparatus as claimed in any preceding claim in which examination of the teat or other object contained within the viewing space of the apparatus is enhanced by means illuminating the object with different optical wavebands and measuring them independently.

7. Viewing apparatus as claimed in Claim 6 in which the illumination means comprises a broad band source operating over a wide wavelength range.

8. Apparatus as claimed in Claim 7 including interference filters to enable the detection device(s) to take independent information in different optical wavebands.

9. Viewing apparatus as claimed in Claim 6 in which the illumination means includes some means of varying the wavelength of a single light source to provide different detection parameters.

10. Viewing apparatus as claimed in Claim 9 in which the wavelength-varying means comprises one or more interference filters which allows the detection device to take independent information in different optical wavebands.

I 1. Viewing apparatus as claimed in Claim 6 in which the illumination means includes two different light sources operating at different wavelengths.

12. Viewing apparatus as claimed in Claim 11 in which the light sources are laser sources.

13. Viewing apparatus as claimed in any of Claims 6 to 12 in which the means for measuring the wavebands independently comprises one or more beamsplitters to split the returned light into different paths.

14. Viewing apparatus as claimed in any preceding claim in which the one or more detection devices are 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.

15. Viewing apparatus as claimed in any of Claims 1 to 14 in which the detection device(s) are mounted independently of the support structure.

16. Viewing apparatus as claimed in Claim 15 in which the light from the reflectors is transmitted down the robot arm using coherent fibre optic bundles to a camera or other detector located externally of the arm.

17. Viewing apparatus as claimed in any preceding claim when intended for use in teat examination, including a cleaning mechanism whereby the detection device(s) and any object-illuminating lighting system are kept clean either during the inspection cycle, or cleaned between cycles.

18. Viewing apparatus as claimed in any preceding claim in which 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.

19. Viewing apparatus as claimed in any of Claims 1 to 18 in which one or more of the reflectors are axially spaced from the viewing space so as to provide an end view of an object or object part contained in the viewing space.

20. Viewing apparatus as claimed in any preceding claim in which the reflectors consist of mirrors.

21. Viewing apparatus as claimed in any preceding claim in which the support structure for the reflectors is mounted with a teat cup holder at the distal end of a same "wrist action" sub-assembly or robot arm acting as the placement means.

22. Viewing apparatus as claimed in Claim 21 in which both the teat cup holder and the detector(s) pivot about the same inclined "wrist" axis in such a way that the robot arm is operable to 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, whereby, after the inspection stage and assuming the teat is deemed to be both clean and healthy, the entire head is pivoted about the wrist axis of the robot and the robot arm then drives the now inverted and correctly orientated teat cup, onto the teat.

23. Viewing apparatus as claimed in any preceding claim combined with an air sampling device thereby to allow assessment of an animal's health and the detection of disease or defects on its udder.

24. Viewing apparatus as claimed in Claim 23 including means 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.

25. Viewing apparatus substantially as hereinbefore described with reference to and/or illustrated in the accompanying drawings.