Patent Application
20160113228
The present invention relates to the cleaning of windows and lenses of optical equipment used in contaminated environments and has particular relevance to cleaning of windows and lenses of equipment used in automatic or semiautomatic milking systems.
An optical detection arrangement, such as is commonly used in automatic milking systems, typically includes a detector in the form of a diode detector or CCD array camera for detecting radiation that is emitted or reflected from an object of interest, and using the detected radiation to determine the distance between the object and the detector. Some systems may also have a radiation source, for example, a laser, used to illuminate objects of interest with suitable radiation. In most cases, the radiation detector and source, if present, are arranged in a housing behind a screen or window that protects the camera or diode from surrounding pollution. The window may be made of glass or other suitably transparent material through which visible light or other radiation can pass substantially without attenuation. In order for an optical detection system of this kind to operate reliably, it is important that the transmission of radiation through the window is not blocked by deposits such as dirt, dust milk or water. Deposits of any kind reduce the amount of optical radiation that can reach the detector and, in systems containing a source of radiation for illuminating an object, may also prevent an object from being illuminated adequately.
A particular challenge in a milking parlour is the extent and range of contaminants that are present. These include urine, manure, milk, dust, hair and also mineral deposits, such as limescale, and disinfectant or cleaning solutions. In present-day automatic milking parlours, where teat cups are connected to an animal's teats automatically, optical detectors are commonplace for detecting the presence of an animal and specifically for determining the position of the teats. The optical detectors are often located close to the teats of an animal, which implies a position that is close to the floor of the milking parlour. As a consequence, all the above contaminants may land on the optical detector and its window.
Existing systems have cleaning devices either provided separately from the detectors or connected to the detector window for washing or wiping the window surface and in some cases drying the protective window with compressed air. For example, EP-A-0688498 describes a cylindrical optical detector used in a milking arrangement that has a sliding cover adapted to move over a window. The cover is equipped with a sponge that is wetted by a cleaning liquid. As the cover slides over the window, the window is wiped by the sponge. U.S. Pat. No. 4,843,561 describes an agricultural harvester with an imaging devices in the form of cameras. These cameras are cleaned by means of a sprayer that sprays cleaning solution and wiper blades that automatically wipe a glass cover that protects the camera. A problem with known arrangements is that over time thin films can build up on the detector window or lens, which impede the detection process. Particularly in environments such as a milking parlour, where contaminants include milk, urine and manure, a thin film of fat or protein deposits can persist, which ultimately degrades the detector operation.
In view of the drawbacks of the above arrangements and methods, it is an object of the present invention to provide a cleaning arrangement for an optical device that is highly effective over time.
In accordance with the present invention, this object is achieved in a milking system that includes an optical detector for detecting radiation emitted and/or reflected by at least part of an animal, the detector having a housing with a window that is substantially transparent to said radiation. The milking arrangement further includes a cleaning device for cleaning the window of the detector. The cleaning device comprises at least one nozzle connected to a source of steam, wherein in operation the nozzle of the cleaning device is configured to direct steam against the window of said optical detector.
It has been discovered by the inventor that directing steam via one or more nozzles onto a window is a highly effective manner of cleaning the window as it offers the combined functions of heating and rinsing but without the inherent drawbacks associated with other cleaning fluids as it is free from impurities and importantly from minerals that can leave deposits and residue on the window, which, over time, may degrade the operation of the optical detector. In this regard it is to be noted that once steam is exposed to atmospheric pressure upon release from a nozzle it is no longer strictly speaking steam, but rather hot vapour. Yet this vapour, unlike heated water, is free from all impurities. For the purposes of this disclosure the term “steam” is used both for steam and vapour.
In a particularly preferred embodiment, the milking system further comprises a controller that is configured to control both the operation of the cleaning arrangement and of the optical detector. This enables the correct sequencing of the associated functions that ensures that the cleaning of the detector window is carried out with minimum disruption and in safe manner that excludes all risk of injury to animals or operators. The milking system may further be arranged to comprise a milking robot with at least one robot arm that is configured to move under the control of a controller, wherein said optical detector is mounted on said robot arm.
According to one embodiment, the controller is configured to control the supply of steam to the cleaning arrangement for a predetermined period prior to applying steam to the optical detector window to purge condensation from said cleaning arrangement. By forcing steam through the nozzle or nozzles of the cleaning arrangement for a certain limited time prior to the cleaning operation, it is ensured that the temperature of the steam used for cleaning is at the optimum level so that the steam has sufficient energy for cleaning the detector window.
While the use a single nozzle is entirely adequate to expose the whole window surface to steam, particularly, when the detector is moved relative to the nozzle throughout the cleaning process, it is equally possible for the cleaning device to comprise at least two nozzles disposed a predetermined distance apart such that in operation the nozzles generate an overlapping jet of steam. By providing such an overlapping steam jet, the coverage of the window can be improved and it is thereby ensured that the whole surface of the detector window is subject to the same degree of cleaning efficiency. This may also be achieved when at least one nozzle is configured to move during the application of steam to said optical detector.
In order to provide an even distribution of steam over the surface of the optical detector window, and thus ensure a uniform heating effect over the whole window it is preferably when the nozzle or nozzles are oriented such that, in operation, an axial extension of the nozzle or nozzles is substantially at right-angles to the optical detector window. This then minimises the localised overheating of any area and ensures a uniform cleaning result.
In a particularly advantageous arrangement the cleaning arrangement further comprises a drying arrangement for drying the detector after the application of steam. Providing such a drying arrangement in the cleaning arrangement enables any water droplets remaining on the window surface after cleaning to be removed immediately, so that the optical detector can be put back into operation with the minimum delay.
In a particularly advantageous embodiment, the drying arrangement includes an air supply arrangement for supplying compressed air to the detector window. The use of compressed air to force water droplets away from the window surface not only dries the window rapidly, but also cools both the window and the optical detector housing, so ensuring that the components within the optical detector remain safely within the operating temperature range, while also minimising any risk of injury to animals or operators who may inadvertently come into contact with a hot detector.
In a particularly advantageous embodiment, the drying arrangement is configured to supply compressed air to the at least one nozzle. In other words the same nozzles are used for supplying both steam and air, which greatly simplifies the cleaning arrangement.
In a particularly advantageous embodiment, the cleaning arrangement further comprises a pre-rinsing arrangement for applying water to said detector window before the application of steam. It has been discovered that rinsing the window prior to cleaning with steam is effective for removing milk protein that can become denaturised when heated and adhere to the surface of the window. This means that the steam applied to the window subsequently can be at a higher temperature than other wise, for example by placing the nozzles closer to the window surface. The rinsing water is preferably purified or distilled water, which is free from minerals and thus would not add to the contamination of the window. The water is also preferably unheated, or heated to a temperature below 60° C.
In a further embodiment, the milking system comprises a milk box for accommodating an animal to be milked, wherein said cleaning arrangement is located at a position outside the milk box. In this regard, the term milk box refers equally to stand-alone stalls in which an individual animal is milked fully or partially automatically, as well as to pens, bays or milking positions in milking parlours that accommodate several animals at a time, including rotary parlours or the like.
In a still further embodiment, the cleaning arrangement is arranged at a position adjacent the optical detector. In this arrangement, the optical detector does not need to be moved to and from the cleaning arrangement.
The invention further resides in a method of cleaning the window of an optical detector that forms part of a milking system as defined in the appended claims and as described further below.
More specifically, a method of cleaning the window of an optical detector that forms part of a milking system is proposed, wherein the optical detector is arranged to detect radiation emitted and/or reflected at least in part by at least part of an animal, and comprises a housing with a window that is substantially transparent to the radiation. The method comprises: cleaning the window by directing steam towards the window from at least one nozzle oriented towards the window. As discussed above the present inventor has discovered that applying steam to the window has proven particularly effective at removing contamination in particular oily films that have a tendency to build up over time on equipment that is exposed to contamination in a dairy environment.
The nozzle or nozzles are preferably oriented at right-angles to window surface in order to ensure uniform application of steam and thus heat. The uniform application of steam and thus of heat can be still further enhanced when the method includes effecting a relative movement between the detector window and the at least one nozzle while directing steam against the window.
In order to reduce the time for cleaning the detector window it is preferable when the window is dried after directing steam towards said window. Once the window is dried it can be put into operation immediately. Drying may be done mechanically, such as using a wiper or cloth. Preferably, however, the method includes drying the window by directing compressed air towards the window.
In a particularly preferred embodiment the method comprises rinsing the window with water prior to directing steam towards said window. This pre-rinsing step aids the removal of milk proteins, which could become denaturised when exposed to the steam cleaning step and adhere to the window surface. By removing these proteins before steam cleaning, the temperature of the steam can be hotter than permitted otherwise, which may improve the cleaning and/or reduce the time needed to clean. The water used for rinsing is preferably purified or distilled water.
The method further comprises the step of evacuating condensed water from the nozzles prior to directing steam towards said window. The supply of steam to a cool nozzles and a cool supply pipeline will result in condensation forming that results in water being forced out of the nozzle or nozzles before steam is issued. This evacuation step may be used as the pre-rinsing step, provided that the condensed water is sufficiently cool, and specifically below about 60° C.
Further objects and advantages of the present invention will become apparent from the following description of the preferred embodiments that are given by way of example with reference to the accompanying drawings. In the figures:
A set of four teat cups 50 connected to milk lines (not shown) are provided in a magazine located beside the robot arm construction 10 within easy reach of the same. Integrated in this teat cup magazine is a teat cup cleaning arrangement 70 for cleaning and disinfecting the teat cups after use. The teat cup cleaning arrangement 70 is connected to a source of steam, such as a boiler 80 via a pipeline and valve 82. This arrangement includes four nozzles over each of which a teat cup 50 can be supported. Each of the nozzles has openings via which steam is supplied to clean and disinfect the teat cup 50. A washing cup 60 for washing an animal's teats one by one is also shown in its rest position arranged beside the robot arm construction. While only one washing cup 60 is illustrated, it will be understood by those skilled in the art that two or more washing cups 60 may be provided to wash more than one teat simultaneously. The structure and function of the teat cups 60 and washing cups 70 are well known to one of ordinary skill in the art and will thus not be described further. The robot arm construction 10 includes a robot arm 11 that is movable both vertically and horizontally and also rotationally to enable it to be moved into one or more precise positions under an animal present in the milk box 30 and also withdrawn to various positions at the side of the milk box 30, including the illustrated rest position. The robot arm 11 carries a gripper 12 at its end which, in the illustrated embodiment, comprises an electromagnet that can be energised to pick up a teat cup 50 or the cleaning cup 60 and de-energised to release the teat and cleaning cups 50, 60. To this end, the teat cups 50 and cleaning cups 60 are provided with an outer casing that is magnetic or is provided with a strip of magnetic material. It will be understood, however, that other systems could replace the electromagnet. For example, opening and closing mechanical elements for physically gripping the teat cups and cleaning cups, or a cup-like element for cradling each teat cup could be employed equally well here.
At the end of the robot arm 11, slightly behind and above the gripper 12, there is arranged an optical detector 40 for detecting and determining the position of the teats of an animal to be milked. In an alternative embodiment, the detector 40 can be arranged on a separate robot arm that is moved independently of the robot arm 11 carrying teat cups. One or more detectors 40 could alternatively be located at a substantially fixed position outside or at the edge of the milk box 30. Also located at the side of the milk box 30 is a cleaning device 100 for cleaning the optical detector. The location of this device 100 is such that the optical detector 40 can be moved into or under this cleaning device 100 using the robot arm 11. The cleaning device 100 is connected to the boiler 80 to receive steam via pipeline and valve 81 and to a compressor 90 for compressed air. Although not illustrated specifically in
A controller, generally indicated by black box 20, controls the operation of the milking robot 1. As illustrated in
The detector 40 is used to generate image or distance data which the controller 20 can subsequently use establish the position of an animal's udder and/or of the individual teats relative to a known position. This is then used to guide the robot arm 11 in a number of operations, such as cleaning the teats, attaching teat cups 60, or effecting an after-treatment. While that detector 40 could determine the positions of the teats relatively quickly, an animal will rarely stay completely still, so that the position of the teats shifts constantly. For this reason, the detector 40 is often used to track the teat positions continuously until the operation in question is completed. An embodiment of the detector 40 is illustrated schematically in more detail in
The detector 40 is constantly exposed to contamination. Typical contaminants include airborne dust and water vapour, mud, manure, urine, water and cleaning liquid splashes, hair and milk. Its arrangement in proximity to the floor and on a robot arm that is moved close to or under the teats of an animal means that the detector window 42 will at some time become spattered with dirt, while airborne contaminants such as dust and water vapour tend to settle on the window as a film. Dried droplets of water can also result in mineral deposits. In addition, the fat contained in milk has a tendency to form a fatty residue over time that is difficult to remove. Yet it is essential for the correct operation of the detector 40, and thus for the correct guidance of the robot arm, that the detector window 42 should not become obscured and impede the transmission of light. In accordance with the present invention, the detector window is cleaned effectively, hygienically and with minimum impact on the environment by using steam.
While the application of steam has been found to clean all impurities that are likely to be present on a detector window 42, it is important to limit the heating effect produced when cleaning. This is due to the need to prevent the various optical and electronic components contained in the detector housing 41 from being heated to or above the maximum recommended operating temperature. This depends partly on the thickness of the detector window and the material of this window, but the temperature of the steam applied to the window 42 and the length of time it is applied must be limited. The application of compressed air to the window 42 also has a cooling effect that can prevent much of the surface heat being transmitted to the inside of the detector housing.
The boiler 80 produces wet or saturated steam. By wet steam is meant saturated steam, namely steam that in equilibrium with heated water and which has not been heated past the boiling point at its pressure. This differs from dry stream or superheated steam, which contains only gas, and a small loss in temperature does not produce condensation. The steam in the boiler heated to 158° C. at a pressure of between 5.5 and 6 Bar. The boiler 80 may also be used to provide steam for disinfecting the teat cups 60. When the steam is released from the nozzles 120 where it is retained under pressure, it will expand under atmospheric pressure and thus attain a temperature no higher than 100° C. Strictly speaking the steam is no longer steam when it reaches the detector window 42 but instead will have been converted to the liquid phase and can better be described as hot vapour. For the purposes of this disclosure however, the term steam will be used for both steam and vapour that is issued from the nozzles 120 when connected to boiler 80. By the time it impacts on the detector window 42, the temperature of the steam will have dropped by an amount that depends on the distance between the nozzles 120 and the window 42 as well as the ambient temperature. It is important to note that the use of steam from boiler 80 ensures that the low temperature steam or hot vapour will contain no impurities or minerals and thus, unlike heated water, will not leave residues on the window surface 42.
While in the illustrated embodiment two nozzles 120 arranged in a fixed position are shown, it will be understood that more nozzles 120 may be provided. Similarly, a single nozzle appropriately spaced may also achieve a sufficient cleaning effect. It is further contemplated that one or more nozzles can be mounted on a movable support that moves the nozzle or nozzles so that the steam sweeps across the surface of the detector window. In such an arrangement there would be no need to move the detector 42.
By means of the relative movement of the detector 42 and nozzles 120 it is ensured that heat is spread over the window surface thus limiting the localised heating effect. This may limit the effects of thermal shock and also prevent residues that may occur when milk proteins present on the detector window are denatured by the heat and adhere to the surface. However, it is also possible to provide an arrangement of nozzles 120 that provide and overlapping steam supply capable of covering the entire window surface 42. In this case, the time needed to supply steam would be shorter, again to minimise the heating of the detector 42.
It has been found that saturated steam provides the best cleaning effect by simultaneously heating and rinsing away impurities, however, any drop in temperature of the steam causes water droplets to condense out. When steam is first applied to pipeline 130 via valve 81 required for cleaning a detector, the temperature of the steam drops within the pipeline 81 causing condensation, which means that initially the nozzles will spray water. In order to remove the condensed water droplets from pipeline 81 and to heat the pipeline sufficiently to prevent further condensation, steam must be supplied from boiler 80 to nozzles 120 for a period before the detector window is in place for cleaning. The longer this pre-heating period, the higher the temperature of the steam, but the more steam wasted. Clearly this will depend on the ambient temperature as well as the length of the pipeline 81. In general, it is believed that a period of between 2 s and 20 s is sufficient to achieve an acceptable steam temperature in the nozzles 120 to clean the detector window 42 effectively. The condensed steam emitted from the pipeline 130 and nozzles 120 may be used to pre-rinse the window, provided that the initial temperature of this water is below around 60° C. In this case, there would be no need to provide the additional pipeline 160 connected to a separate source of rinsing water.
In operation, when the detector window 42 is to be cleaned, the controller 20 initially effects the pre-rinsing of the window surface 42. This may be achieved by controlling the robot arm 11 to bring the detector 40 into a cleaning position in the detector cleaning arrangement 100 and connecting the nozzles 120 to a source of rinsing water. Alternatively, the controller 20 opens the supply of steam to the nozzles 120 of the cleaning arrangement 100 and allows steam to flow for a certain period of time to remove any condensed water that may have collected in the pipeline. The steam then continues to flow for the designated cleaning period, which may be between 2 s and 25 s, after which the supply to pipeline 130 is cut via valve 81 and the nozzles are connected to the compressor 90 via pipeline 140 again for a predetermined period, but preferably between 10 and 30 s until the detector window 42 is dry and the detector housing 41 cooled. During the pre-rinsing, steaming and drying periods, the controller 20 controls the movement of the robot arm such that all the window surface 42 rinsed, cleaned and dried substantially uniformly.
In both illustrated embodiments of the cleaning arrangement 100 compressed air is used to dry the detector window 42, 420. However, since the steam is free of impurities and minerals commonly present in water, other drying devices could be employed that can effectively remove any water droplets from the detector 42, 420. Possible devices include mechanical wipers constituted by flexible blades, cloths or sponges that are capable of scraping or wiping away residual water.
It will be understood that the described arrangement can be applied to other milking arrangements that require the use of optical detectors. In this regard, it is noted that optical detectors may be employed for other tasks than determining the positions of the teats of an animal. For example, they may be used to determine the position of an animal relative to equipment, to identify animals that show certain behaviour that may indicate illness, an injury or fertility. Optical detectors in the form of cameras may also be used to provide remote monitoring of an installation. The cleaning arrangement described above can be applied to any of these systems. Similarly, a milking system is not limited to the illustrated embodiments, but may also include systems in which some of the operations are performed by operators, but also systems in which several animals are milked collectively, such as rotary systems or collective milking parlours.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1350745-4 | Jun 2013 | SE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SE2014/050738 | 6/17/2014 | WO | 00 |
