WO2021036655A1 - Checkweigher - Google Patents

Checkweigher Download PDF

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Publication number
WO2021036655A1
WO2021036655A1 PCT/CN2020/105374 CN2020105374W WO2021036655A1 WO 2021036655 A1 WO2021036655 A1 WO 2021036655A1 CN 2020105374 W CN2020105374 W CN 2020105374W WO 2021036655 A1 WO2021036655 A1 WO 2021036655A1
Authority
WO
WIPO (PCT)
Prior art keywords
conveying belt
shape
information
checkweigher
width
Prior art date
Application number
PCT/CN2020/105374
Other languages
French (fr)
Inventor
Shenhui Wang
Song Zhang
Conghan CAO
Qin Sun
Original Assignee
Mettler-Toledo (Changzhou) Measurement Technology Ltd.
Mettler-Toledo (Changzhou) Precision Instruments Ltd.
Mettler-Toledo International Trading (Shanghai) Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mettler-Toledo (Changzhou) Measurement Technology Ltd., Mettler-Toledo (Changzhou) Precision Instruments Ltd., Mettler-Toledo International Trading (Shanghai) Co., Ltd. filed Critical Mettler-Toledo (Changzhou) Measurement Technology Ltd.
Publication of WO2021036655A1 publication Critical patent/WO2021036655A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G23/00—Auxiliary devices for weighing apparatus
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G11/00—Apparatus for weighing a continuous stream of material during flow; Conveyor belt weighers
    • G01G11/003—Details; specially adapted accessories
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/04—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness specially adapted for measuring length or width of objects while moving
    • G01B11/043—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness specially adapted for measuring length or width of objects while moving for measuring length
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/04—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness specially adapted for measuring length or width of objects while moving
    • G01B11/046—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness specially adapted for measuring length or width of objects while moving for measuring width
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0608—Height gauges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0691—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of objects while moving
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
    • G01G19/002—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for postal parcels and letters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
    • G01G19/40—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/002—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/04—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness specially adapted for measuring length or width of objects while moving
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes

Definitions

  • the present invention relates to a checkweigher, and in particular to a checkweigher with an object shape recognition function.
  • weighing data is generally filtered or corrected in terms of a belt feature, a belt movement rate, and a vibration frequency of the checkweigher.
  • the weighing performance of the checkweigher is not only affected by the characteristics of the checkweigher itself, but also by the external environment. In other words, the weighing performance is affected by factors such as shape attribute of a checked object and position attribute of the checked object on a checkweighing conveying belt. Consequently, existing checkweighers can hardly achieve high-precision weighing performance.
  • the present invention aims to solve the problem in the prior art by providing a checkweigher with an object dimension recognition function, in which a shape dimension of an object and the position of the object on a conveying belt are recognized to compensate for weighing data, so as to improve the weighing precision.
  • the present invention provides a checkweigher comprising a conveying belt for conveying an object.
  • the checkweigher is characterized by an object shape recognition apparatus for detecting and recognizing information about shape of a contact surface between an object conveyed on a conveying belt of the checkweigher and the conveying belt and for information about position of the object on the conveying belt.
  • the checkweigher comprises a calculation unit for querying or calculating a correction parameter using the information about the shape and the information about the position of the object on the conveying belt, and correcting the weight of the object obtained by the checkweigher using the correction parameter.
  • the object shape recognition apparatus is used to detect and recognize information including the shape of the contact surface between the object and the conveying belt, and information such as length and width of the shape, and an included angle between the shape and the conveying belt, and the information about the position of the object on the conveying belt, and a corresponding correction is performed, to remove an impact, on weighing precision, of the object at different positions on the conveying belt in dynamic weighing, so as to improve the weighing performance.
  • the information about the shape in the present invention further comprises information about the center or the center of gravity of the object.
  • the information about the position comprises coordinates of the object in a width direction of the conveying belt and in a length direction of the conveying belt.
  • the object shape recognition apparatus detects and recognizes the width and length of the shape of the contact surface between the object on the conveying belt and the conveying belt, or recognizes the width and length of the shape, and an included angle between a width direction and/or a length direction of the shape and a movement direction or a width direction of the conveying belt.
  • the object shape recognition apparatus further detects and recognizes information about distances between the object and edges of the conveying belt, or information about distances between the center or the center of gravity of the object and the edges of the conveying belt; and the correction parameter is queried or calculated by using the width and length of the shape, or by using the width and length of the shape and the included angle, and the information about the distances between the object and the edges of the conveying belt or the information about the distances between the center or the center of gravity of the object and the edges of the conveying belt, and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
  • the object shape recognition apparatus detects and recognizes the width and length of the shape of the contact surface between the object on the conveying belt and the conveying belt, or recognizes the width and length of the shape, and an included angle between a width direction and/or a length direction of the shape and a movement direction or a width direction of the conveying belt.
  • the object shape recognition apparatus further detects and recognizes information about distances between the object and two edges of the conveying belt in the width direction thereof, or information about distances between the center or the center of gravity of the object and two edges of the conveying belt in the width direction thereof.
  • the correction parameter is queried or calculated by using width and length of the shape, or by using width and length of the shape, and the included angle, and the information about the distances between the object and the two edges of the conveying belt in the width direction thereof, or the information about the distances between the center or the center of gravity of the object and the two edges of the conveying belt in the width direction thereof, and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
  • the object shape recognition apparatus detects and recognizes the shape of the contact surface between the object on the conveying belt and the conveying belt, and calculates an equivalent width and equivalent length of the shape, and an included angle between an equivalent width direction and/or an equivalent length direction and a movement direction or a width direction of the conveying belt, or calculates an equivalent length of the shape in a conveying direction of the conveying belt and an equivalent width of the shape in a width direction of the conveying belt.
  • the object shape recognition apparatus further detects and recognizes information about distances between the object and edges of the conveying belt, or information about distances between the center or the center of gravity of the object and the edges of the conveying belt.
  • the correction parameter is queried or calculated by using the equivalent width and equivalent length of the shape, and the included angle, or by using the equivalent length of the shape in the conveying direction of the conveying belt, the equivalent width of the shape in the width direction of the conveying belt, and the information about the distances between the object and the edges of the conveying belt, or the information about the distances between the center or the center of gravity of the object and the edges of the conveying belt, and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
  • the object shape recognition apparatus detects and recognizes the shape of the contact surface between the object on the conveying belt and the conveying belt, and calculates an equivalent width and equivalent length of the shape, and an included angle between an equivalent width direction and/or an equivalent length direction and a movement direction or a width direction of the conveying belt, or calculates an equivalent length of the shape in a conveying direction of the conveying belt and an equivalent width of the shape in a width direction of the conveying belt.
  • the object shape recognition apparatus further detects and recognizes information about distances between the object and two edges of the conveying belt in the width direction thereof, or information about distances between the center or the center of gravity of the object and two edges of the conveying belt in the width direction thereof.
  • the correction parameter is queried or calculated by using the equivalent width and equivalent length of the shape, and the included angle, or by using the equivalent length of the shape in the conveying direction of the conveying belt, the equivalent width of the shape in the width direction of the conveying belt, and the information about the distances between the object and the two edges of the conveying belt in the width direction thereof, or the information about the distances between the center or the center of gravity of the object and the two edges of the conveying belt in the width direction thereof, and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
  • the information about the distances is distances between the object and edges of the conveying belt in the width direction of the conveying belt, that is, a direction perpendicular to the movement direction of the conveying belt, and distances between the object and edges of the conveying belt in the length direction of the conveying belt, that is, the movement direction of the conveying belt, when the object is on the conveying belt.
  • the equivalent length and equivalent width are the length and width that can represent a shape and that are obtained after the actually recognized and detected shape is abstracted through existing algorithm calculation.
  • Weighed weight is corrected with a part of information about the shape of the object and the information about the position of the object on the conveying belt, so that calculation complexity is reduced, and a requirement for a calculation unit or a system configuration is reduced.
  • the object shape recognition apparatus comprises at least one camera and an image recognition unit that are arranged above the conveying belt, wherein the camera collects an image of the conveying belt and the object conveyed on the conveying belt, and the image recognition unit recognizes the object in the image collected by the camera, and determines information about the shape of the contact surface between the object and the conveying belt and the information about the position of the object on the conveying belt.
  • the object shape recognition apparatus comprises a camera arranged to have a photographing direction facing towards a plane of the conveying belt, and a camera arranged to have a photographing direction perpendicular to a movement direction of the conveying belt.
  • the object shape recognition apparatus comprises a camera arranged to have a photographing direction facing a plane of the conveying belt, a camera arranged to have a photographing direction perpendicular to a movement direction of the conveying belt, and a camera arranged to have a photographing direction facing the movement direction of the conveying belt.
  • information about other features of the object is acquired by arranging more cameras.
  • the object shape recognition apparatus comprises upright rods arranged on two opposing sides of the conveying belt, wherein a plurality of photoelectric sensors are arranged on each of the upright rods, and a light source is arranged at the top of each of the upright rods such that light emitted by the light source is reflected by the conveying belt and the object conveyed on the conveying belt, and then received by the photoelectric sensors.
  • the object shape recognition apparatus further comprises a processing unit that determines information about the shape of the contact surface between the object and the conveying belt and the information about the position of the object on the conveying belt based on signals output by the photoelectric sensors.
  • the information about the dimension and position of the object can be also obtained by an existing method of scanning an object on a conveying belt with light.
  • the object shape recognition apparatus comprises a linear image sensor arranged above the conveying belt, wherein the linear image sensor collects image information of the object passing by the linear image sensor during movement with the conveying belt.
  • the object shape recognition apparatus further comprises a processing unit that determines information about the shape of the contact surface between the object and the conveying belt and the information about the position of the object on the conveying belt based on image information output by the linear image sensor.
  • the object is scanned during the movement thereof on the conveying belt, so as to obtain the information about the shape of the object while it is on the conveying belt.
  • the object shape recognition apparatus further comprises a photoelectric switch and a counter, wherein the photoelectric switch is arranged on one side of the conveying belt, such that when the photoelectric switch detects passing of the object conveyed on the conveying belt, the counter is activated to perform a counting function, and when the photoelectric switch does not detect passing of the object, the counter is deactivated to stop performing a counting function.
  • the image recognition unit or the processing unit calculates the length of the object based on the counter and a conveying speed.
  • a combination of the photoelectric switch and the counter is used to simplify calculation of the length of an object.
  • the present invention further provides a checkweighing system, characterized by comprising a checkweigher described above, a feeding apparatus for feeding an object to be weighed to the checkweigher, and a processing apparatus that performs a corresponding operation based on weight data obtained by the checkweigher and information about the shape of the object.
  • Applying the checkweigher of the present invention to a checkweighing system can provide valuable inputs for subsequent processing steps such as sorting and selecting, charging, and printing of a label, in conjunction with the information about the shape of the object and on the basis that an accurate weighing value is provided for a subsequent processing apparatus.
  • the positive effect of the present invention is that the weighing data is compensated and corrected by recognizing the shape and position of the object on the conveying belt thereof so as to remove impact of a detected object on dynamic weighing value, thereby improving weighing precision.
  • Fig. 1 is a schematic view of a checkweigher of an embodiment of the present invention.
  • Fig. 2 is a schematic view of a checkweigher of another embodiment of the present invention.
  • Fig. 3 is a schematic view of a checkweigher of still another embodiment of the present invention.
  • an object shape recognition apparatus is installed in space above a conveying belt or on either side of a conveying belt, which recognizes the shape of a contact surface between an object and the conveying belt, for example, the length and width of the contact surface, and moreover, establishes a coordinate system relative to the conveying belt and recognizes coordinates of the object on the conveying belt or obtains only information about the lateral position of the object that is perpendicular to a movement direction of the conveying belt.
  • Weighing data is corrected and compensated with the information about the shape of the contact surface and the coordinates or the lateral position of the object on the conveying belt. Therefore, the precision of the output object weight data is improved, and higher weighing performance is achieved.
  • a camera 2 is arranged directly above a conveying belt 1 of a checkweigher in this embodiment, wherein the camera 2 faces towards the conveying belt 1 and can photograph a belt surface of the conveying belt 1 to obtain a status picture.
  • FIG. 1 a picture of a package being conveyed on the belt photographed by the camera 2 is shown in FIG. 1, wherein the picture comprises an image of the complete package, and an image of the belt displayed in the picture covers the whole belt width X.
  • a calculation unit calculates, by using an existing image recognition algorithm, an actual length L and actual width W of the object in the picture, and distances (x1, x2) between edges of the conveying belt and two edges of the object that face the conveying belt, so as to obtain the position of the package on the conveying belt.
  • an image monitoring function is used in which the camera 2 is woken up whenever there is a change in the content of pictures from the camera 2 to take a photo of a package being conveyed on the conveying belt 1.
  • a photoelectric switch is used to detect movement of an object on the conveying belt.
  • a photographing function of the camera is triggered, so as to obtain a photo of the package being conveyed on the conveying belt.
  • the hardware costs are reduced due to the triggering of the photographing only when the movement of an object is detected.
  • a computer receives the photographed picture of the object, and obtains a correction parameter according to a preset mapping relationship between a correction parameter and length of the object, width of the object, and position of the object on the conveying belt.
  • the computer corrects a weighed weight CW obtained when the package passes through the checkweigher, to obtain a corrected weighed weight FW of the package.
  • the computer receives the photographed picture, recognizes the shape of a contact surface between the object and the conveying belt and the position of the object on the conveying belt, that is, distances between the object and edges of the conveying belt in a width direction and in a length direction.
  • the computer calculates the length and width of the object, and included angles between edges of the object and a conveying direction of the conveying belt based on the shape, and in turn calculates a corrected weighed weight of the object according to a preset correction algorithm, with data of the shape of the object and the position of the object on the conveying belt which are taken as parameters and the weighed weight obtained when the object passes by the checkweigher being input to the algorithm.
  • the shape of the object is irregular, and the shape of a contact surface between the object and the conveying belt is also irregular.
  • the irregular shape recognized from the picture is processed by an existing image processing algorithm to calculate an equivalent length and equivalent width of the object, and an included angle between a length direction or a width direction and a conveying direction of the conveying belt.
  • an equivalent length and an equivalent width of the irregular shape respectively in the conveying direction of the conveying belt and in the width direction of the conveying belt are even directly calculated. Then, the weighed weight of the object is corrected by using the correction algorithm in the above embodiment.
  • two cameras are arranged above the conveying belt of the checkweigher, and a coordinate system is established with respect to the conveying belt, wherein the movement direction of the conveying belt is taken as a Y axis, the width direction of the conveying belt is taken as an X axis, and a direction perpendicular to the conveying belt is taken as a Z axis.
  • One camera with a photographing direction along the X axis photographs a side surface of the object on the conveying belt, so as to recognize the length and height of the object.
  • the other camera with the photographing direction which is along the Z axis and faces towards the conveying belt photographs a top surface of the object on the conveying belt, so as to recognize the width of the object and distances between two edges of the object and edges of the conveying belt. Then, the weighed weight of the object is corrected by way of the calculation of the correction coefficient as described in the embodiment shown in FIG. 1.
  • a camera is arranged in each coordinate axis direction.
  • the shape and the position of the object can be obtained, but also information such as a specific dimension of the object, can be obtained.
  • the weighed weight of the object can be corrected by way of the calculation of the correction coefficient as described in the embodiment shown in FIG. 1.
  • the position of the center or center of gravity of the object can be estimated according to the information about the shape of the object, which is then used to obtain a correction parameter according to a preset mapping relationship between a correction parameter and the length of the object, the width of the object, the position of the center or center of gravity of the object on the conveying belt, and then the weighed weight of the object is corrected.
  • position information of the barycentre position or the centre position of the object, from the edges of the conveying belt, in the width direction and in a length direction thereof are obtained, and the length of the object, the width of the object, and the position of the center of gravity or the center of the object on the conveying belt are input to a preset correction function, to calculate a corresponding correction parameter, and the weighed weight of the object is corrected.
  • two upright rods 3a are arranged on two sides of a conveying belt 1a of a checkweigher, and a photoelectric sensor and a corresponding light source 4a are arranged on each of the upright rods 3a.
  • the received reflected light is used to determine distances (xa1, xa2) between two edges of the object and the edges of the conveying belt and the width Wa of the object. Furthermore, in this embodiment, the length La of the object is calculated by means of a pulse counter, the speed of the conveying belt 1, and a signal from the upright rod 3a for detecting whether an object has passed by.
  • a computer then calculates a corresponding correction parameter according to a preset correction function, with the length of the object, the width of the object, and the position of the object on the conveying belt being input to the function. Then, the computer corrects the weighed weight CWa of the package obtained when the package passes through the checkweigher, to obtain a corrected weighed weight FWa of the package.
  • cameras 4b are arranged on each of the upright rods 3a, and the cameras 4b are used to recognize image information of an object passing by, so as to obtain distances between two edges of the object and the edges of the conveying belt and the width of the object. Then, the length is calculated by way of the calculation of the object dimension as described in the embodiment shown in FIG. 2.
  • a rod positioned parallel to the conveying belt is arranged above the conveying belt, and a linear image sensor is arranged on the rod along the width direction of the conveying belt.
  • the linear image sensor faces towards the conveying belt, and acquires image information when an object moves with the conveying belt below the rod, so as to obtain distances between two edges of the object and the edges of the conveying belt and the width of the object. Then, the length is calculated by way of the calculation of the object dimension as described in the embodiment shown in FIG. 2.
  • a single-chip microcomputer calculates a corrected weighed weight of the object according to a correction algorithm stored therein, with the length of the object, the width of the object, and the position of the object on the conveying belt which are taken as parameters and the weighed weight of the object obtained when the object passes through the checkweigher is input to the algorithm.
  • a person skilled in the art can further use other existing object dimension recognizing devices on the basis of the apparatus for detecting the shape of a contact surface between an object and the conveying belt and the position of the object in the examples described above, to implement similar detection and calculation of the shape of the contact surface between the same object and the conveying belt and the position of the object.
  • the description set forth in the above embodiments gives no limitation to the form of the apparatus for detecting the shape of the contact surface between the object and the conveying belt and the position of the object.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The present invention discloses a checkweigher comprising a conveying belt (1,1a)for conveying an object. The checkweigher comprises an object shape recognition apparatus for detecting and recognizing information about the shape of a contact surface between the object conveyed on the conveying belt (1,1a) of the checkweigher and the conveying belt (1,1a) and information about the position of the object on the conveying belt (1,1a). The checkweigher further comprises a calculation unit for querying or calculating a correction parameter with the information about the shape and the information about the position of the object on the conveying belt (1,1a), and correcting the weight of the object obtained by the checkweigher with the correction parameter. By means of the present invention, weighing data is compensated and corrected by recognizing the dimension of the object on the conveying belt(1,1a) and the position thereof on the conveying belt (1,1a), to remove impact of the detected object on dynamic weighing, thereby improving the weighing precision.

Description

CHECKWEIGHER BACKGROUND OF THE INVENTION Technical Field
The present invention relates to a checkweigher, and in particular to a checkweigher with an object shape recognition function.
Background Art
Currently, in order to improve weighing performance of a checkweigher in a dynamic weighing process, weighing data is generally filtered or corrected in terms of a belt feature, a belt movement rate, and a vibration frequency of the checkweigher.
However, the weighing performance of the checkweigher is not only affected by the characteristics of the checkweigher itself, but also by the external environment. In other words, the weighing performance is affected by factors such as shape attribute of a checked object and position attribute of the checked object on a checkweighing conveying belt. Consequently, existing checkweighers can hardly achieve high-precision weighing performance.
SUMMARY
The present invention aims to solve the problem in the prior art by providing a checkweigher with an object dimension recognition function, in which a shape dimension of an object and the position of the object on a conveying belt are recognized to compensate for weighing data, so as to improve the weighing precision.
The present invention provides a checkweigher comprising a conveying belt for conveying an object. The checkweigher is characterized by an object shape recognition apparatus for detecting and recognizing information about shape of a contact surface between an object conveyed on a conveying belt of the checkweigher and the conveying belt and for information about position of the object on the conveying belt. The checkweigher comprises a calculation unit for querying or calculating a correction parameter using the information about the shape and the information about the position of the object on the conveying belt, and correcting the weight of the object obtained by the checkweigher using the correction parameter.
In the present invention, the object shape recognition apparatus is used to detect and recognize information including the shape of the contact surface between the object and the conveying belt, and information such as length and width of the shape, and an included angle between the shape and the conveying belt, and the information about the position of the object on the conveying belt, and a corresponding correction is performed, to remove an impact, on weighing precision, of the object at different positions on the conveying belt in dynamic weighing, so as to improve the weighing performance.
In addition to the length and the width of the shape, and the included angle between the shape and the conveying belt, the information about the shape in the present invention further comprises information about the center or the center of gravity of the object. The information about the position comprises coordinates of the object in a width direction of the conveying belt and in a length direction of the conveying belt.
Preferably, the object shape recognition apparatus detects and recognizes the width and length of the shape of the contact surface between the object on the conveying belt and the conveying belt, or recognizes the width and length of the shape, and an included angle between a width direction and/or a length direction of the shape and a movement direction or a width direction of the conveying belt.
The object shape recognition apparatus further detects and recognizes information about distances between the object and edges of the conveying belt, or information about distances between the center or the center of gravity of the object and the edges of the conveying belt; and the correction parameter is queried or calculated by using the width and length of the shape, or by using the width and length of the shape and the included angle, and the information about the distances between the object and the edges of the conveying belt or the information about the distances between the center or the center of gravity of the object and the edges of the conveying belt, and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
The object shape recognition apparatus detects and recognizes the width and length of the shape of the contact surface between the object on the conveying belt and the conveying belt, or recognizes the width and length of the shape, and an included angle between a width direction and/or a length direction of the shape and a movement direction or a width direction of the conveying belt. The object shape recognition apparatus further detects and recognizes information about distances between the  object and two edges of the conveying belt in the width direction thereof, or information about distances between the center or the center of gravity of the object and two edges of the conveying belt in the width direction thereof. The correction parameter is queried or calculated by using width and length of the shape, or by using width and length of the shape, and the included angle, and the information about the distances between the object and the two edges of the conveying belt in the width direction thereof, or the information about the distances between the center or the center of gravity of the object and the two edges of the conveying belt in the width direction thereof, and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
The object shape recognition apparatus detects and recognizes the shape of the contact surface between the object on the conveying belt and the conveying belt, and calculates an equivalent width and equivalent length of the shape, and an included angle between an equivalent width direction and/or an equivalent length direction and a movement direction or a width direction of the conveying belt, or calculates an equivalent length of the shape in a conveying direction of the conveying belt and an equivalent width of the shape in a width direction of the conveying belt. the object shape recognition apparatus further detects and recognizes information about distances between the object and edges of the conveying belt, or information about distances between the center or the center of gravity of the object and the edges of the conveying belt. The correction parameter is queried or calculated by using the equivalent width and equivalent length of the shape, and the included angle, or by using the equivalent length of the shape in the conveying direction of the conveying belt, the equivalent width of the shape in the width direction of the conveying belt, and the information about the distances between the object and the edges of the conveying belt, or the information about the distances between the center or the center of gravity of the object and the edges of the conveying belt, and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
The object shape recognition apparatus detects and recognizes the shape of the contact surface between the object on the conveying belt and the conveying belt, and calculates an equivalent width and equivalent length of the shape, and an included angle between an equivalent width direction and/or an equivalent length direction and a movement direction or a width direction of the conveying belt, or calculates an equivalent length of the shape in a conveying direction of the conveying belt and an equivalent width of the shape in a width direction of the conveying belt. The object shape recognition apparatus further detects and recognizes information about  distances between the object and two edges of the conveying belt in the width direction thereof, or information about distances between the center or the center of gravity of the object and two edges of the conveying belt in the width direction thereof. The correction parameter is queried or calculated by using the equivalent width and equivalent length of the shape, and the included angle, or by using the equivalent length of the shape in the conveying direction of the conveying belt, the equivalent width of the shape in the width direction of the conveying belt, and the information about the distances between the object and the two edges of the conveying belt in the width direction thereof, or the information about the distances between the center or the center of gravity of the object and the two edges of the conveying belt in the width direction thereof, and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
The information about the distances is distances between the object and edges of the conveying belt in the width direction of the conveying belt, that is, a direction perpendicular to the movement direction of the conveying belt, and distances between the object and edges of the conveying belt in the length direction of the conveying belt, that is, the movement direction of the conveying belt, when the object is on the conveying belt.
The equivalent length and equivalent width are the length and width that can represent a shape and that are obtained after the actually recognized and detected shape is abstracted through existing algorithm calculation.
Weighed weight is corrected with a part of information about the shape of the object and the information about the position of the object on the conveying belt, so that calculation complexity is reduced, and a requirement for a calculation unit or a system configuration is reduced.
Preferably, the object shape recognition apparatus comprises at least one camera and an image recognition unit that are arranged above the conveying belt, wherein the camera collects an image of the conveying belt and the object conveyed on the conveying belt, and the image recognition unit recognizes the object in the image collected by the camera, and determines information about the shape of the contact surface between the object and the conveying belt and the information about the position of the object on the conveying belt.
Preferably, the object shape recognition apparatus comprises a camera arranged to have a photographing direction facing towards a plane of the conveying belt, and a  camera arranged to have a photographing direction perpendicular to a movement direction of the conveying belt.
The object shape recognition apparatus comprises a camera arranged to have a photographing direction facing a plane of the conveying belt, a camera arranged to have a photographing direction perpendicular to a movement direction of the conveying belt, and a camera arranged to have a photographing direction facing the movement direction of the conveying belt.
In the present invention, in addition to obtaining by calculation the information about the shape of the object, information about other features of the object is acquired by arranging more cameras.
Preferably, the object shape recognition apparatus comprises upright rods arranged on two opposing sides of the conveying belt, wherein a plurality of photoelectric sensors are arranged on each of the upright rods, and a light source is arranged at the top of each of the upright rods such that light emitted by the light source is reflected by the conveying belt and the object conveyed on the conveying belt, and then received by the photoelectric sensors. The object shape recognition apparatus further comprises a processing unit that determines information about the shape of the contact surface between the object and the conveying belt and the information about the position of the object on the conveying belt based on signals output by the photoelectric sensors.
In the present invention, the information about the dimension and position of the object can be also obtained by an existing method of scanning an object on a conveying belt with light.
Preferably, the object shape recognition apparatus comprises a linear image sensor arranged above the conveying belt, wherein the linear image sensor collects image information of the object passing by the linear image sensor during movement with the conveying belt. The object shape recognition apparatus further comprises a processing unit that determines information about the shape of the contact surface between the object and the conveying belt and the information about the position of the object on the conveying belt based on image information output by the linear image sensor.
In the present invention, the object is scanned during the movement thereof on the conveying belt, so as to obtain the information about the shape of the object while it is on the conveying belt.
Preferably, the object shape recognition apparatus further comprises a photoelectric switch and a counter, wherein the photoelectric switch is arranged on one side of the conveying belt, such that when the photoelectric switch detects passing of the object conveyed on the conveying belt, the counter is activated to perform a counting function, and when the photoelectric switch does not detect passing of the object, the counter is deactivated to stop performing a counting function. The image recognition unit or the processing unit calculates the length of the object based on the counter and a conveying speed.
In the present invention, a combination of the photoelectric switch and the counter is used to simplify calculation of the length of an object.
The present invention further provides a checkweighing system, characterized by comprising a checkweigher described above, a feeding apparatus for feeding an object to be weighed to the checkweigher, and a processing apparatus that performs a corresponding operation based on weight data obtained by the checkweigher and information about the shape of the object.
Applying the checkweigher of the present invention to a checkweighing system can provide valuable inputs for subsequent processing steps such as sorting and selecting, charging, and printing of a label, in conjunction with the information about the shape of the object and on the basis that an accurate weighing value is provided for a subsequent processing apparatus.
The positive improvement effects of the present invention are as follows:
The positive effect of the present invention is that the weighing data is compensated and corrected by recognizing the shape and position of the object on the conveying belt thereof so as to remove impact of a detected object on dynamic weighing value, thereby improving weighing precision.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other features, properties, and advantages of the present invention become clearer based on the description below in conjunction with the drawings and embodiments, and the same reference numeral always represents the same feature.
Fig. 1 is a schematic view of a checkweigher of an embodiment of the present invention.
Fig. 2 is a schematic view of a checkweigher of another embodiment of the present invention.
Fig. 3 is a schematic view of a checkweigher of still another embodiment of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
To make the above objectives, features and advantages of the present invention more apparent and easier to understand, specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings.
Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Reference will now be made in detail to preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The same reference numerals used in all the figures denote identical or similar parts wherever possible.
Furthermore, although the terms used in the present invention are selected from well-known common terms, some of the terms mentioned in the description of the present invention may have been selected by the applicant according to his or her determination, and the detailed meaning thereof is described in the relevant section described herein.
Furthermore, the present invention must be understood, not simply by the actual terms used but also by the meanings encompassed by each term.
For a checkweigher in the present invention, an object shape recognition apparatus is installed in space above a conveying belt or on either side of a conveying belt, which recognizes the shape of a contact surface between an object and the conveying belt, for example, the length and width of the contact surface, and moreover, establishes a coordinate system relative to the conveying belt and recognizes coordinates of the object on the conveying belt or obtains only information about the lateral position of the object that is perpendicular to a movement direction of the conveying belt. Weighing data is corrected and compensated with the information about the shape of the contact surface and the coordinates or the lateral position of the object on the conveying belt. Therefore, the precision of the output object weight data is improved, and higher weighing performance is achieved.
Modes for carrying out the present invention are described below by way of example in the following embodiments.
As shown in FIG. 1, a camera 2 is arranged directly above a conveying belt 1 of a checkweigher in this embodiment, wherein the camera 2 faces towards the conveying belt 1 and can photograph a belt surface of the conveying belt 1 to obtain a status picture.
In this embodiment, a picture of a package being conveyed on the belt photographed by the camera 2 is shown in FIG. 1, wherein the picture comprises an image of the complete package, and an image of the belt displayed in the picture covers the whole belt width X.
In this embodiment, while the conveying belt 1 is running, if no object is moving on the conveying belt, the content of pictures obtained by the camera 2 is not changed, so that no operation is to be performed; and when a package having length L and width W that is shown in FIG. 1 moves on the conveying belt, the content of pictures obtained by the camera 2 is changed, in which case a calculation unit calculates, by using an existing image recognition algorithm, an actual length L and actual width W of the object in the picture, and distances (x1, x2) between edges of the conveying belt and two edges of the object that face the conveying belt, so as to obtain the position of the package on the conveying belt.
In this embodiment, an image monitoring function is used in which the camera 2 is woken up whenever there is a change in the content of pictures from the camera 2 to take a photo of a package being conveyed on the conveying belt 1.
In another embodiment, a photoelectric switch is used to detect movement of an object on the conveying belt. When an object is passing through a detection area of the photoelectric switch, a photographing function of the camera is triggered, so as to obtain a photo of the package being conveyed on the conveying belt. In this embodiment, the hardware costs are reduced due to the triggering of the photographing only when the movement of an object is detected.
A computer receives the photographed picture of the object, and obtains a correction parameter according to a preset mapping relationship between a correction parameter and length of the object, width of the object, and position of the object on the conveying belt. The computer corrects a weighed weight CW obtained when the package passes through the checkweigher, to obtain a corrected weighed weight FW of the package.
In a variant, the computer receives the photographed picture, recognizes the shape of a contact surface between the object and the conveying belt and the position of the object on the conveying belt, that is, distances between the object and edges of the conveying belt in a width direction and in a length direction. The computer calculates the length and width of the object, and included angles between edges of the object and a conveying direction of the conveying belt based on the shape, and in turn calculates a corrected weighed weight of the object according to a preset correction algorithm, with data of the shape of the object and the position of the object on the conveying belt which are taken as parameters and the weighed weight obtained when the object passes by the checkweigher being input to the algorithm.
In still another variant, the shape of the object is irregular, and the shape of a contact surface between the object and the conveying belt is also irregular. In this case, the irregular shape recognized from the picture is processed by an existing image processing algorithm to calculate an equivalent length and equivalent width of the object, and an included angle between a length direction or a width direction and a conveying direction of the conveying belt. Alternatively, an equivalent length and an equivalent width of the irregular shape respectively in the conveying direction of the conveying belt and in the width direction of the conveying belt are even directly calculated. Then, the weighed weight of the object is corrected by using the correction algorithm in the above embodiment.
In still another embodiment, two cameras are arranged above the conveying belt of the checkweigher, and a coordinate system is established with respect to the conveying belt, wherein the movement direction of the conveying belt is taken as a Y axis, the width direction of the conveying belt is taken as an X axis, and a direction perpendicular to the conveying belt is taken as a Z axis. One camera with a photographing direction along the X axis photographs a side surface of the object on the conveying belt, so as to recognize the length and height of the object. The other camera with the photographing direction which is along the Z axis and faces towards the conveying belt photographs a top surface of the object on the conveying belt, so as to recognize the width of the object and distances between two edges of the object and edges of the conveying belt. Then, the weighed weight of the object is corrected by way of the calculation of the correction coefficient as described in the embodiment shown in FIG. 1.
In an alternative implementation, a camera is arranged in each coordinate axis direction. In this case, not only the shape and the position of the object can be obtained,  but also information such as a specific dimension of the object, can be obtained. In this embodiment, the weighed weight of the object can be corrected by way of the calculation of the correction coefficient as described in the embodiment shown in FIG. 1. In addition, in this embodiment, when the object has an even mass distribution, the position of the center or center of gravity of the object can be estimated according to the information about the shape of the object, which is then used to obtain a correction parameter according to a preset mapping relationship between a correction parameter and the length of the object, the width of the object, the position of the center or center of gravity of the object on the conveying belt, and then the weighed weight of the object is corrected.
In still another variant, after the position of the center or center of gravity of the object is estimated, distances between the position of the center or center of gravity and two edges of the conveying belt are obtained, and the length of the object, the width of the object, and position of the center or center of gravity in the width direction of the conveying belt are input to a preset correction function, to calculate a corresponding correction parameter, and the weighed weight of the object is corrected.
In another variant, after the position of the center or center of gravity of the object is estimated, position information of the barycentre position or the centre position of the object, from the edges of the conveying belt, in the width direction and in a length direction thereof are obtained, and the length of the object, the width of the object, and the position of the center of gravity or the center of the object on the conveying belt are input to a preset correction function, to calculate a corresponding correction parameter, and the weighed weight of the object is corrected.
In another embodiment shown in FIG. 2, two upright rods 3a are arranged on two sides of a conveying belt 1a of a checkweigher, and a photoelectric sensor and a corresponding light source 4a are arranged on each of the upright rods 3a.
In this embodiment, when a package is passing through a plane formed by the upright rods 3a, the received reflected light is used to determine distances (xa1, xa2) between two edges of the object and the edges of the conveying belt and the width Wa of the object. Furthermore, in this embodiment, the length La of the object is calculated by means of a pulse counter, the speed of the conveying belt 1, and a signal from the upright rod 3a for detecting whether an object has passed by.
A computer then calculates a corresponding correction parameter according to a preset correction function, with the length of the object, the width of the object, and the  position of the object on the conveying belt being input to the function. Then, the computer corrects the weighed weight CWa of the package obtained when the package passes through the checkweigher, to obtain a corrected weighed weight FWa of the package.
In still another embodiment, as shown in FIG. 3, cameras 4b are arranged on each of the upright rods 3a, and the cameras 4b are used to recognize image information of an object passing by, so as to obtain distances between two edges of the object and the edges of the conveying belt and the width of the object. Then, the length is calculated by way of the calculation of the object dimension as described in the embodiment shown in FIG. 2.
In another embodiment, a rod positioned parallel to the conveying belt is arranged above the conveying belt, and a linear image sensor is arranged on the rod along the width direction of the conveying belt. The linear image sensor faces towards the conveying belt, and acquires image information when an object moves with the conveying belt below the rod, so as to obtain distances between two edges of the object and the edges of the conveying belt and the width of the object. Then, the length is calculated by way of the calculation of the object dimension as described in the embodiment shown in FIG. 2.
A single-chip microcomputer calculates a corrected weighed weight of the object according to a correction algorithm stored therein, with the length of the object, the width of the object, and the position of the object on the conveying belt which are taken as parameters and the weighed weight of the object obtained when the object passes through the checkweigher is input to the algorithm.
A person skilled in the art can further use other existing object dimension recognizing devices on the basis of the apparatus for detecting the shape of a contact surface between an object and the conveying belt and the position of the object in the examples described above, to implement similar detection and calculation of the shape of the contact surface between the same object and the conveying belt and the position of the object. The description set forth in the above embodiments gives no limitation to the form of the apparatus for detecting the shape of the contact surface between the object and the conveying belt and the position of the object.
Although the specific implementations of the present invention are described above, a person skilled in the art should understand that these are only exemplary, and the scope of protection of the present invention is defined by the attached claims. Various  alterations or modifications to these implementations can be made by a person skilled in the art without departing from the principle and essence of the present invention; however, these alterations and modifications all fall within the scope of protection of the present invention.
Reference signs list
1, 1a                       conveying belt
2                           camera
3a                          upright rods
4a                          light source
4b                          camera arranged on the upright rods 3a
X                           width of the conveying  belt  1, 1a
x1, x2, xa1, xa2            distances between edges of the conveying belt and two
                            edges of the object that face the conveying belt
L, La                       length of the object
W, Wa                       width of the object

Claims (12)

  1. A checkweigher comprising a conveying belt (1, 1a) for conveying an object, the checkweigher is characterized by an object shape recognition apparatus for detecting and recognizing information about shape of a contact surface between the object conveyed on a conveying belt (1, 1a) of the checkweigher and the conveying belt (1, 1a) and for information about position of the object on the conveying belt (1, 1a) ; and a calculation unit for querying or calculating a correction parameter using the information about the shape and the information about the position of the object on the conveying belt (1, 1a) , and correcting weight of the object obtained by the checkweigher using the correction parameter.
  2. The checkweigher of claim 1, characterized in that in the checkweigher, the object shape recognition apparatus detects and recognizes width (W, Wa) and length (L, La) of the shape of the contact surface between the object on the conveying belt (1, 1a) and the conveying belt (1, 1a) , or recognizes the width (W, Wa) and length (L, La) of the shape, and an included angle between a width direction and/or a length direction of the shape and a movement direction or a width direction of the conveying belt (1, 1a) ; and the object shape recognition apparatus further detects and recognizes information about distances (x1, x2, xa1, xa2) between the object and edges of the conveying belt (1, 1a) , or information about distances between center or center of gravity of the object and the edges of the conveying belt (1, 1a) ; and the correction parameter is queried or calculated by using the width (W, Wa) and length (L, La) of the shape, or by using the width (W, Wa) and length (L, La) of the shape and the included angle, and the information about the distances (x1, x2, xa1, xa2) between the object and the edges of the conveying belt (1, 1a) or the information about the distances between the center or the center of gravity of the object and the edges of the conveying belt (1, 1a) , and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
  3. The checkweigher of claim 1, characterized in that the object shape recognition apparatus detects and recognizes the width (W, Wa) and length (L, La) of the shape of the contact surface between the object on the conveying belt (1, 1a) and the conveying belt (1, 1a) , or recognizes the width (W, Wa) and length (L, La) of the shape, and an included angle between a width direction and/or a length direction of the shape and a movement direction or a width direction of the conveying belt (1, 1a) ; and the object shape recognition apparatus further detects and recognizes information about distances (x1, x2, xa1, xa2) between the object and two edges of the conveying belt (1, 1a) in the width direction thereof, or information about distances between the center or the center of gravity of the object and two edges of the conveying belt (1, 1a) in the width direction thereof; and the correction  parameter is queried or calculated by using the width (W, Wa) and length of the shape, or by using the width (W, Wa) and length (L, La) of the shape, and the included angle, and the information about the distances (x1, x2, xa1, xa2) between the object and the two edges of the conveying belt (1, 1a) in the width direction thereof, or the information about the distances between the center or the center of gravity of the object and the two edges of the conveying belt (1, 1a) in the width direction thereof, and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
  4. The checkweigher of claim 1, characterized in that the object shape recognition apparatus detects and recognizes the shape of the contact surface between the object on the conveying belt (1, 1a) and the conveying belt (1, 1a) , and calculates an equivalent width (W, Wa) and equivalent length (L, La) of the shape, and an included angle between an equivalent width direction and/or an equivalent length direction and a movement direction or a width direction of the conveying belt (1, 1a) , or calculates an equivalent length (L, La) of the shape in a conveying direction of the conveying belt (1, 1a) and an equivalent width (W, Wa) of the shape in a width direction of the conveying belt (1, 1a) ; the object shape recognition apparatus further detects and recognizes information about distances (x1, x2, xa1, xa2) between the object and edges of the conveying belt (1, 1a) , or information about distances between the center or the center of gravity of the object and the edges of the conveying belt (1, 1a) ; and the correction parameter is queried or calculated by using the equivalent width (W, Wa) and equivalent length (L, La) of the shape, and the included angle, or by using the equivalent length (L, La) of the shape in the conveying direction of the conveying belt (1, 1a) , the equivalent width (W, Wa) of the shape in the width direction of the conveying belt (1, 1a) , and the information about the distances (x1, x2, xa1, xa2) between the object and the edges of the conveying belt (1, 1a) , or the information about the distances between the center or the center of gravity of the object and the edges of the conveying belt (1, 1a) , and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
  5. The checkweigher of claim 1, characterized in that the object shape recognition apparatus detects and recognizes the shape of the contact surface between the object on the conveying belt (1, 1a) and the conveying belt (1, 1a) , and calculates an equivalent width (W, Wa) and equivalent length (L, La) of the shape, and an included angle between an equivalent width direction and/or an equivalent length direction and a movement direction or a width direction of the conveying belt (1, 1a) , or calculates an equivalent length (L, La) of the shape in a conveying direction of the conveying belt (1, 1a) and an equivalent width (W, Wa) of the shape in a width direction of the conveying belt (1, 1a) ; the object shape  recognition apparatus further detects and recognizes information about distances between the object and two edges of the conveying belt (1, 1a) in the width direction thereof, or information about distances between the center or the center of gravity of the object and two edges of the conveying belt (1, 1a) in the width direction thereof; and the correction parameter is queried or calculated by using the equivalent width (W, Wa) and equivalent length (L, La) of the shape, and the included angle, or by using the equivalent length (L, La) of the shape in the conveying direction of the conveying belt (1, 1a) , the equivalent width (W, Wa) of the shape in the width direction of the conveying belt (1, 1a) , and the information about the distances between the object and the two edges of the conveying belt (1, 1a) in the width direction thereof, or the information about the distances between the center or the center of gravity of the object and the two edges of the conveying belt (1, 1a) in the width direction thereof, and the weight of the object obtained by the checkweigher is corrected with the correction parameter.
  6. The checkweigher as claimed in any of the preceding claims, characterized in that the object shape recognition apparatus comprises at least one camera (2) and an image recognition unit that are arranged above the conveying belt (1, 1a) , wherein the camera (2) collects an image of the conveying belt (1, 1a) and the object conveyed on the conveying belt (1, 1a) , and the image recognition unit recognizes the object in the image collected by the camera (2) , and determines information about the shape of the contact surface between the object and the conveying belt (1, 1a) and the information about the position of the object on the conveying belt (1, 1a) .
  7. The checkweigher as claimed in claim 6, characterized in that the camera (2) is arranged to have a photographing direction facing towards a plane of the conveying belt (1, 1a) and perpendicular to a movement direction of the conveying belt (1, 1a) .
  8. The checkweigher as claimed in claims 6, characterized in that the object shape recognition apparatus comprises a camera (2) arranged to have a photographing direction facing a plane of the conveying belt (1, 1a) , a camera (2) arranged to have a photographing direction perpendicular to a movement direction of the conveying belt (1, 1a) , and a camera (2) arranged to have a photographing direction facing the movement direction of the conveying belt (1, 1a) .
  9. The checkweigher as claimed in any of the preceding claims, characterized in that the object shape recognition apparatus comprises upright rods (3a) arranged on two opposing sides of the conveying belt (1, 1a) , wherein a plurality of photoelectric sensors are arranged on each of the upright rods (3a) , and a light source (4a) is arranged at the top of each of the  upright rods (3a) ; such that light emitted by the light source (4a) is reflected by the conveying belt (1, 1a) and the object conveyed on the conveying belt (1, 1a) , and then received by the photoelectric sensors; wherein the object shape recognition apparatus further comprises a processing unit that determines information about the shape of the contact surface between the object and the conveying belt (1, 1a) and the information about the position of the object on the conveying belt (1, 1a) based on signals output by the photoelectric sensors.
  10. The checkweigher as claimed in any of the preceding claims, characterized in that the object shape recognition apparatus comprises a linear image sensor arranged above the conveying belt (1, 1a) , wherein the linear image sensor gathers image information of the object moving along with the conveying belt (1, 1a) ; wherein the object shape recognition apparatus further comprises a processing unit that determines information about the shape of the contact surface between the object and the conveying belt (1, 1a) and the information about the position of the object on the conveying belt (1, 1a) based on image information output by the linear image sensor.
  11. The checkweigher as claimed in any of the preceding claims, characterized in that the object shape recognition apparatus further comprises a photoelectric switch and a counter, wherein the photoelectric switch is arranged on one side of the conveying belt (1, 1a) such that when the photoelectric switch detects passing of the object conveyed on the conveying belt (1, 1a) , the counter is activated to perform a counting function, and when the photoelectric switch does not detect passing of the object, the counter is deactivated to stop performing a counting function; and the image recognition unit or the processing unit determines length (L, La) of the object based on the counting function and a conveying speed of the conveying belt (1, 1a) .
  12. A checkweighing system, characterized by comprising a checkweigher as claimed in any of the preceding claims, a feeding apparatus for feeding an object to be weighed on to the checkweigher, and a processing apparatus that performs a corresponding operation based on weight data obtained by the checkweigher and information about shape of the object.
PCT/CN2020/105374 2019-08-30 2020-07-29 Checkweigher WO2021036655A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
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CN201910814330.7 2019-08-30

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