GB2087550A - Apparatus for measurement of volume and related parameters - Google Patents

Abstract

The apparatus is used to obtain an at least approximate measure of volume (or volume-related parameter such as weight) of an article, e.g. fish. The article is located in a measuring zone between light sources (20, 22) and light cell arrays (24, 26) whose photosensitive surfaces are masked by the article so that the electrical outputs of the arrays provides an indication of the degree of masking which, in turn, is used to provide a corresponding volume or weight value. The measuring zone is water-tight to permit the passage of water containing the fish. <IMAGE>

Description

SPECIFICATION Apparatus for measurement of.volume and related parameters This invention relates to apparatus for obtaining an at least approximate measure of the volume and/or a volume-related parameter (such as weight) of an article.

Although not limited thereto, the invention has particular application to the in-water weighing of fish in for example fish farming establishments.

Hitherto weighing of fish has involved manhandling the fish to remove them from the water and perform the weighing operation. This not only tends to be time consuming but is also extremely stressful to the fish and their development and physical well being may be retarded for at least several days; for these reasons the present method is not considered satisfactory.

The object of the present invention is to provide improved volume measuring apparatus and in particular such apparatus which, when applied to the weighing of fish, reduces or eliminates the drawbacks referred to above.

According to the present invention we provide apparatus for obtaining an at least approximate measure of the volume and/or a volume related parameter of an article, comprising a radiation sensitive area or areas providing an electrical output or outputs related to the amount of radiation falling onto said area or areas and means irradiating said area or areas, said means and said area(s) being so arranged that the article to be measured can be interposed therebetween to mask the amount of radiation falling on said area(s), and means for indicating the change in magnitude of said electrical output(s) caused by the masking of said area(s) and thereby afford an at least approximate measure of volume or related parameter.

Preferably there are at least two such areas disposed in angular relationship to each other so that the masking of said areas by the article is dependent upon the cross section of the article in at least two different planes. For example, if two such areas are employed, they are conveniently disposed at right angles to one another so that the masking depends upon the cross sections of the article in two mutually orthogonal planes. Where three such areas are employed, they may be disposed at angles of typically 1200 with respect to one another. Although it is preferred to provide at least two such areas, in some circumstances only a very-approximate measure of volume (or related parameter) may be required and it is conceivable in such circumstances that only one radiation sensitive area may be necessary.

Each such area may comprise a series of light sensitive cells disposed side-by-side (and possibly in a row and column. arrangement) so as to present a light sensitive area which may be generally planar or of arcuate configuration and the electrical outputs of the individual cells may be processed separately or collectively. In the latter event for example, the electrical outputs of the cells constituting each area may be connected in series to provide a collective output for further processing. If desired, the collective outputs from each area may be connected in series to provide a single electrical output whose magnitude will be dependent upon the degree of masking to which the areas, considered collectively, are subjected.

The further processing of the output(s) from said area(s) may involve for example conversion of the volume measure represented by the output(s) into another parameter by scaling or otherwise modifying the output(s). For example, in the case of fish, the body density of a given species is substantially constant and consequently a measure of weight can be obtained from the volume measure provided by said area(s) by appropriate modification of the electrical output(s) from said area(s).

Where the apparatus of the invention is intended for the weighing of fish, the preferred embodiment may comprise a duct of which at least part of the length is composed of a transparent or translucent material so that said area(s) can be located about its periphery with the irradiating means disposed so that the radiation traverses the width of the duct before impinging on said area(s). The irradiating means and said area(s) may be enclosed within a watertight enclosure surrounding the duct which will be arranged so that fish can be introduced at one end and withdrawn at the other end. In this way, the weighing operation can, if desired, be performed without removing the fish from their natural environment, i.e. by immersing the apparatus in the tank, pond or such like so that the fish can pass through the duct.

Preferably the arrangement is such that a flow of water is created through the duct so as to control movement of the fish through the duct.

Such a flow may be gravity induced or it may be achieved by means of a pumping arrangement. A valve arrangement may be disposed adjacent the outlet end of the duct to stop the flow (and hence each individual fish) temporarily while each measurement and a corresponding print-out for example is made. The valve arrangement may be controlled by means of a sensing device or devices associated with the duct such that, when the fish reaches a predetermined position along the length of the duct, the valve is closed until the measuring cycle is completed whereupon the valve is again opened to resume the flow until the next fish reaches the measuring section.

The apparatus of the invention may be used in conjunction with means for separating the fish into different grades or sizes, i.e. according to the measured values obtained. Thus, there may be some form of gating means located downstream of the measuring section which is operated; according to the measured values, to direct or channel each fish into one of a number of zones representing different grades or sizes.

Conveniently the apparatus will include a printer or other device for producing a permanent or semi-permanent record of each measurement and a counting device may also be provided to record the number of fish passing through the apparatus.

Although the invention is described above in terms of the volume measurement/weighing of fish, it will be appreciated that the invention may have application to for example manufacturing industry in circumstances where there is a requirement for volume measurement of articles or, where the articles have a substantially constant density, weight measurement.

In order to promote further understanding of the invention, one embodiment will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a longitudinal sectional view through apparatus of the invention; Figure 2 is a transverse section through the apparatus; and Figure 3 is a schematic block diagram showing the circuitry of the apparatus.

Referring now to the drawings, as shown in Figures 1 and 2 the apparatus comprises a duct 10 having an inlet 12 and an outlet 14. The duct may be of square cross section and will be sufficiently large in cross section to enable fish of a selected size range to pass through from the inlet to the outlet. In practice, different duct sizes may be necessary for fish of different size ranges.

The duct has a measuring zone 16 midway between its ends and is made of transparent or translucent material such as glass at least over the length of the measuring section 16. The length of the measuring section 16 is sufficiently long to accommodate the range of fish lengths to be encountered in practice. The measuring zone of the duct 10 is enclosed within a waterproof enclosure 1 8 so as to protect the various components of the measuring system when the apparatus is immersed in water. The ends of the duct 10 project from or are at least flush with the enclosure 18 so that fish can enter and leave the duct. Fish may be fed through the duct either by immersing the apparatus in a pond or tank or alternatively by means of pipes fitted to the inlet and outlet of the duct.

The measuring system comprises two light sources 20. 22 each consisting of for example a pair of fluorescent tubes, and the light receiving sections 24. 26 are arranged as shown in Figures 1 and 2 so that section 24 responds primarily to light produced by the source 20 and the section 26 responds primarily to light produced by the source 22. The tubes conveniently emit their light via diffusers 28, 30 to provide even light distribution and both the light receivers and the sources are slightly spaced from the duct 10 by spacers to minimise the effect of extraneous light.

Each receiving section 24, 26 comprises a series of photosensitive devices such as solar cells which provide an electrical output related to the amount of light falling on them. The cells are shown distributed longitudinally of the duct but other distributions are possible, for example a column and row arrangement. In the illustrated embodiment, the cells of each section 24, 26 may be connected electrically in series and the two sections may also be connected in series to provide an analogue output, via leads 34, dependent upon the amount of light falling on the two sections.

Adjacent the leading end of the duct 10 means is provided for detecting the presence of a fish approaching the outlet. Such means may be in the form of one or more (two are shown) photo diodes 35 which emit an output via leads 36 when light input to the photo diode is interrupted by the presence of a fish in the duct 10. This output can then be used to initiate a measuring cycle and related operations such as grading as will be explained below. The outputs from the photo diode 35 may control a solenoid operated valve which, in turn, controls water flow (which may be gravity induced or pumped) through the ducts such that valve closure halts flow to enable a measuring cycle and print-out to be completed before the next fish enters the measuring zone.

Referring now to the block diagram in Figure 3, the measuring zone is shown schematically and for simplicity only one light source/receiver 22. 26 is illustrated. In the quiescent state, i.e. with no fish present in the measuring zone, substantially all of the light emitted by the sources 20, 22 is collected by solar cells24, 26 which collectively provide a maximum electrical analogue signal which is interpreted by the measuring circuitry as zero weight. When a fish passes through the measuring zone, the analogue signal decreases as a a result of partial masking of the solar cells 24, 26 by the fish. The interruption is in effect three dimensional, i.e. the cells 26 being masked by the body length and depth of the fish and the cells 24 being masked by the body length and width of the fish.The decrease is therefore at least approximately proportional to the fish volume and because volume is closely proportional to weight for a given species, the decrease may be interpreted as a weight.

The collective analogue output from the cells 24, 26 is fed to the first stage of the measurement circuitry 40 which comprises an operational amplifier 42 connected in the inversion mode and operating as an invertor/subtractor whereby the maximum cell output is converted to zero and a specific factor is subtracted to enable the analogue outputs corresponding to different fish sizes to be scaled or adjusted in such a way that they can be subsequently acted upon by a common diviser. In practice, the subtraction factor will require to be varied in accordance with the strength of illumination provided by the light sources and the physical and optical characteristics of the glass chamber and the relative positioning of both or either the solar cells and the light sources.

The output from the invertor/subtractor 42 is fed to a second operational amplifier 44 configured to operate as a multiplier in order to improve the analogue resolution. The following stage comprises a potential divider 46 such as a potentiometer which divides the input signals received from the multiplier 44 by the previously mentioned common diviser. The final stage comprises a voltage follower circuit 48 for providing impedance matching between the divider 48 and a digital volt meter which affords an indication of the input voltage after processing via the circuitry 40.

As previously mentioned, each measuring cycle is initiated when the fish to be measured interrupts the light falling on the photo diodes 35 or like sensors. The output from the photo diodes 35 operates a period timer 52 which, in turn, operates: (a) a stop timer 54 which stops the fish within the chamber by means of the stop solenoid 55 which actuates the previously mentioned valves; (b) a sample/print timer 56 which commands a printer 57 to print the sample being presented by the digital volt meter 50; and (c) a grade timer 58 which initiates end of measurement sequence, deenergisation of the stop solenoid and operation of the appropriate grade paths (shown schematically by reference numeral 61,62 and 63) as determined by decoder 64, 65 and 66. The number of grade paths may be varied as required and the grade path is determined during the print command sequence.

Thus, according to the weight measurement, a given fish after leaving the measuring zone will be directed along one of the paths 61, 62 and 63.

Although as described above, each fish is stopped while in the measuring zone, it is envisaged that in a modification the sampling procedure may be carried out without stopping the fish, i.e. weighing-in-motion. If desired, the output information from the measuring circuitry may also be fed into a computer or electronic storage for statistical analysis.

Although the invention is described above in terms of using light-cell arrays, in a modification one or more television/video cameras may be used so that the degree of masking of the lightsensitive signal plate thereof affords variation in the signal output of the or each tube, which variation can be processed to derive a measurement of volume or other related parameter. The invention may be used for measurements of objects other than fish. If desired, the or each array of light cells or the or each camera tube and/or the associated source may be angularly displaceable about an axis intermediate the array/tube and source so that scanning of the object can be carried out to enable the degree of masking to be determined at different #angular positions. In this event, only one source and one light cell array or camera may be necessary.

Claims (13)

1. Apparatus For obtaining an at least approximate measure of the volume and/or a volume related parameter of an article, comprising a radiation-sensitive area or areas providing an electrical output or outputs related to the amount of radiation falling onto said area or areas and means irradiating said area or areas, said means and said area(s) being so arranged that the article to be measured can be interposed therebetween to mask the amount of radiation falling on said area(s), and means for indicating the change in magnitude of said electrical output(s) caused by the masking of said area(s) and thereby afford an at least approximate measure of volume or related parameter.

2. Apparatus as claimed in Claim 1 in which there are at least two such areas disposed in angular relationship to each other so that the masking of said areas by the article is dependent upon the cross section of the article in at least two different planes.

3. Apparatus as claimed in Claim 2 in which two such areas are employed disposed at right angles to one another so that the masking depends upon the cross sections of the article in two mutually orthogonal planes.

4. Apparatus as claimed in any one of Claims 1 to 3 in which the or each radiation-sensitive area is constituted by the light-sensitive signal plate of a television camera.

5. Apparatus as claimed in any one of Claims 1-3 in which the or each such area comprises an array of radiation-sensitive cells.

6. Apparatus as claimed in any one of Claims 1-4 in which the or each area is of generally planar configuration.

7. Apparatus as claimed in any one of Claims 1-4 in which the or each area is of generally arcuate configuration.

8. Apparatus as claimed in any one of Claims 1-7 in which the or each radiation-sensitive area and/or the or each source is displaceable angular about an axis intermediate each such area and the source.

9. Apparatus as claimed in any one of Claims 1-8 including a duct of which at least of the length is composed of a transparent or translucent material so that said area(s) can be located about its periphery with the irradiating means disposed so that the radiation traverses the width of the duct before impinging on said area(s).

10. Apparatus as claimed in Claim 9 in which the irradiating means and said area(s) are enclosed within a watertight enclosure surrounding the duct.

1 Apparatus as claimed in claim 9 or 10 including means for creating a flow of water through the duct.

12. Apparatus as claimed in Claim 11 including means for arresting the flow temporarily to enable a measurement to be made.

13. Apparatus for obtaining an at least approximate measure of the volume and/or a volume related parameter of an article, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.