AU683057B2 - Non-contact volume measurement - Google Patents

Description

Regulation 3,2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: *.0 .00: 0 Invention Title: NON-CONTACT VOLUME MEASUREMENT S S 55

S.

*555 55 S S 5* S. S S S 55 The following statement Is a full description of this invention, including the best method of performing it known to us NON-CONTACT VOLUME MEASUREMENT Technical Field The present invention relates to the measurement of volume, particularly but not exclusively for packages.

Background Art in applications such as postage, freight, shipping and the like it is often desired to measure or estimate the volume of packages. Charging is generally conducted not only in relation to the weight of an article, but also in relation to the volume of the article. It will be appreciated that a large but light package may occupy a disproporticnatO part of available carriage space if charging is based on weight alone. Hence, at a certain weight volume ratio, volume, not weight, becomes the dominant factor for transport and delivery charges.

Despite the economic importance of reliable volume measurement, no system for volume measurement has found wide acceptance other than manual techniques using a tape measure, calculation of volume, and reference to charging tables. This system is error prone, time consuming and does not allow e:e" for consistent standards to be applied.

Another technique has been used for airlines, utilising photoelectric cells spaced at pre-determined distances on a moving belt so as to provide a coarse estimate of volume.

It is an object of the present invention to provide a device capable of consistent and simple volume measurement.

Summary of Invention According to one aspect the present invention provides a method of measuring the volume of a generally cuboidal article, comprising the steps of: providing a reference device having 3 reference axes; 0. be placing an article to be measured in a predetermined position with rospect to the axes; capturing an image of said article and said axes; processing said image and determining the dimensions of said article by reference to the extent to which each of said axes is obscured by said article; and 2 calculating the volume of the article.

Preferably the reference device comprises 3 substantially perpendicular arms with a contrasting reference indicia to facilitate simplified processing and image acquisition. Preferably, indicia are internally illuminated. Most preferably, the reference indicia emits visible light.

Preferably, image acquisition is via a single, fixed electronic camera device, most preferably a video camera.

Cuboidal is defined to mean throughout the specification and claims an object with 6 generally rectangular faces, i.e. a rectangular parallelepiped. The invention further encompasses the measurement of parcels for which the smallest cuboidal enclosing envelope can be defined using the method of the present invention, for example an L- shaped parcel. The present arrangement will not, however, measure accurately an irregular shaped article or one which is, for example, spherical.

15 According to another aspect the present invention provides a device for measuring the volume of a generally cuboidal article, comprising in combination: oleo a reference means having 3 reference axes; image acquisition means; 20 processing means; and calculating means, the arrangement being such that when an article is operatively positioned on said reference means, an image of the reference means and said article is acquired, the image is processed and the dimensions of said article in the direction of said axes are determined by reference to the extent to which the article obscures said axes, and a volume measurement is calculated by reference to said dimensions.

Preferably the reference means comprises 3 substantially mutually perpendicular arms, each including reference indicia. Preferably the indicia are internally illuminated.

Preferably the image acquisition means is a single, fixed electronic camera device, most preferably a video camera.

The inventive arrangement allows for relatively simple processing, as most of the parameters are fixed only the extent of obscuring of the axes is variable. The arrangement is simple and can be readily used with little or no training, and is capable of a high degree of accuracy. The article need not be contacted, and so the invention may be applied to a continuous conveyor situation.

Brief Description of Drawings One embodiment of the invention will now be described with reference to the accompanying figures, in which: Figure 1 illustrates schematically the operation of the inventive volume measurement arrangement; Figure 2 illustrates the video scan lines used in one embodiment; Figure 3 illustrates the arrangement with an article positioned for measurement; ooooo 1 5 Figure 4 illustrates the dimension measurement with detected scan lines S.shown corresponding to figure 3; and Figure 5 is a block diagram of the associated electronic control and processing circuitry.

Description Referring to figure 1, the core compoents of the illustrated embodimnent of the present invention are a video camera 20, In a fixed position, and a set of reference bars 11, 12, 13 disposed about mutually perpendicular axes 10 what we will refer to as x, y and z directions. Figure 2 shows the view from the *see 660 perspective of the camera 20 of bars 11, 12, 13. Although it will b appreciated that a variety of techniques may be used, the image acquisition and measurement will be described with reference to scan lines and rows in a standard video format. It can be seen that with no parcel present, each bar appears to the camera to span a given number of scan lines -N in the Z direction, L in the Y direction and M in the X direction.

The image is electronically divided into these 3 parts, and the number of available scan lines is determined,.

Referring to figure 3, a parcel 25 of dimensions P, T x S is placed so as to abut the y and z axes. Thus, considering figure 4, only reduced numbers of scan lines m, I, n can be seen. Thus, the number of lines in each dimension visible define the initial bar length (say) m less the parcel size, and each dimension can be derived. Preferably, a conversion table is stored in memory to allow for calculation of the volume directly from the detected I, m, n values.

This provides a non-contact measurement which can be readily performed automatically.

The illustrative system may be calibrated by simply covering a known 1 0 length of the bar, and counting the corresponding number of scan lines.

It will be understood that the largest object which can be measured is determined by the height of each bar. In the illustrated embodiment, any object with dimensions P x Tx S, where A a> P a, B b> T> b, and C c S c can be measured. It will be understood that the level of accuracy will depend on 1 5 the relative geometry of camera placement and object size, as well as the number of scan lines provided by the camera.

It is noted that although perpendicular axes are preferred, the invention could equally be implemented with axes at different angles, with suitable modifications to the processing method to calibrate for such an arrangement.

Similarly, while use of a single camera is preferred for simplicity, the invention could equally be implemented with multiple cameras for instance, one for each dimension.

It is also preferred, in a postal situation, that the device incorporate scales so as to allow simultaneous weight and volume measurement. Scales having an output which is compatible with a label printing and/or cash register arrangement are well known to those skilled in the art. The scales may communicate with the control circuitry for the volume measuring system to allow a weight/volume corrected total measurement signal to be displayed or alternatively both may communicate directly with a label printing/cash receipting machine for automatic cost calculation and label printing. In this arrangement, no extra work over weighing is required to produce a postage label for a customer.

I it will be appreciated that the system is equally applicable to checking parcels for correct postage in an automated sorting system or the like.

Referring to figure 5, the general arrangement of the necessary electronic control and processing system according to this embodiment of the invention is shown.

Basic Operation of the F.lectronic Circuitry for the Non-contact Measurement Using Video Camera After video signal is input to the signal processing circuitry, the following signals are output: 1 0 Bar signals represent the detection of the axis bar by the video camera; Sync signal represents the horizontal sync signal for each scan line of the video amera; Field signal represents the vertical sync signal for each field of the video camera; 5 Frame signal represents odd/even frame of the video scan field.

Together with the above signals, control signals from the computer output o** are input to the logic control circuitry. The control signals are: measure, top, left and right etc. These signals enable the whole video image to be divided into three areas and be processed separately Bar out signal from the logic control circuitry Is fed to the counter circuitry, where the video scan lines are counted corresponding to the bar being detected.

A stop count circuit is designed to stop the counter when two consecutive video scan fields are completed. Then, the computer reads the counting result provided by the counter circuitry. This process is repeated for the three divided areas of video image.

By looking up a preset table through calibration, the length of the bar which is obtained from the video image is determined and displayed on the display.

The keyboard is used for sending command to the computer to perform certain tasks such as check calibration, measure or cancel.

F.

6 It will be appreciated that variations and additions are possible within the general inventive concept described.

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Claims (14)

1. A method of determining the volume of a generally cubL al article, comprising the steps of: providing a reference device having 3 non-parallel reference axes; placing an article to be measured within the reference device in a' predetermined position with respect to said axes; providing a means for and capturing an image of said axes and said article in relation to said axes; providing a means for and processing said image; determining in said processing means the dimensions of said article by reference to the extent to which each of said axes is obscured by said article; and calculating in said processing means the volume of the article based on the determined dimensions. cco

2. A method according to claim 1, wherein said reference device comprises 3 substantially perpendicular arms disposed about said axes. s' 3. A method according to claim 2, wherein said arms are provided with contrasting reference indicia.

4. A method according to claim 3, wherein said indicia are internally illuminated. A method according to any one of the preceding claims, wherein said image capturing means comprise an electronic camera device.

6. A method according to claim 5, wherein said camera is in a fixed position in relation to the reference device, 1

7. A method of determining the pricing of freight for an article, comprising: determining the volume of said article in accordance with any one of claims 1 to 6; providing a means for and weighing said article; providing a means for weighing and communicating the weight of said article to a calculating device; providing means for and communicating information relating to the calculated volume to said calculating device; and calculating in said calculating device an applicable price by reference to said volume and weight in accordance with a predefined set of instructions.

8. A method according to claim 7, wherein the weighing means comprise a scale. 9, A method according to claim 8, further comprising the step of providing a means for and printing a label in accordance with the calculated price.

10. Apparatus for determining the volume of a generally cuboidal article, comprising in combination: se a reference device having 3 non-parallel reference axes, said device adapted to receive said article in a predetermined position with respect to said axes; a image acquisition means arranged to acquire an image of said reference axes and said article and provide information relating thereto; processing means arranged to process said information received from said image acquisition means; and calculating means operatively cc, !nected with said processing means, 4'r o V 0 the arrangement being such that when said article is positioned in said reference device, an image of the axes of said reference device and said article is acquired, the image is processed and the dimensions of said article in the direction of said axes are determined by reference to the extent to which the article obscures said axes, and the volume of said article is calculated by reference to said dimensions.

11. Apparatus according to claim 10, wherein said reference device comprises 3 substantially perpendicular arms disposed about said axes.

12. Apparatus according to claim 11, wherein said arms are provided with contrasting reference indicia. SW CC

13. Apparatus according to claim 12, wherein said indicia are internally illuminated. 14, Apparatus according to any one of claims 10 to 13, wherein said image acquisition means comprises an electronic camera device, C see" 15. Apparatus according to claim 14, wherein said camera is in a fixed position in relation to the reference device. *fee* :0000 S16. Apparatus adapted to determine the pricing of freight for a generally cuboidal article, comprising in combination: an apparatus for determining volume according to any one of claims 10 to weighing means disposed to weight said article and output weight information relating thereto; price calculation means arranged to receive, via communicating means, said weight information and information relating to the volume of the article determined in the volume determining apparatus; said price calculating device arranged to calculate the applicable price by reference to said volume and weight information in accordance with a predefined set of instructions.

17. Apparatus according to claim 16, wherein the weighing means comprise a scale.

18. Apparatus according to claim 16 or 17, further comprising means for printing a label in accordance with the calculated price.

19. A method of determining the volume of a generally cuboidal article substantially as hereinbefore described with reference to the accompanying drawings.

20. Apparatus for determining the volume of a generally cuboidal article substantially as hereinbefore described with reference to the accompanying drawings. Ca DATED this 31st day of July, 1997. THE AUSTRALIAN POSTAL CORPORATION SWATERMARK PATENT TRADEMARK ATTORNEYS LEVEL 4, AMORY GARDENS 2 CAVILL AVENUE ASHFIELD NSW 2131 PNF:CJS:GL DOC 033 AU000PL9722.WPC t. I ABSTRACT A method and apparatus for determining the volume of an article are disclosed, particularly for postage and freight applications. The apparatus in one embodiment includes three mutually perpendicular reference axes, with reference indicia marked on the axes, and a fixed camera device such as a video camera. The dimensions are determined by the extent to which an article obscures the camera image of the article, and the volume may then be calculated. The apparatus may also communicate with an automated pricing device, e.g. a cash register. *ooe S **0 S *e S I