WO1998014046A1

WO1998014046A1 - Method and apparatus for the quality assessment of seed

Info

Publication number: WO1998014046A1
Application number: PCT/NL1997/000551
Authority: WO
Inventors: Jacobus Marinus Oggel
Original assignee: van der Have D J BV
Current assignee: van der Have D J BV
Priority date: 1996-10-04
Filing date: 1997-10-06
Publication date: 1998-04-09
Anticipated expiration: 1999-04-04
Also published as: AU4473997A; NL1004209C2

Abstract

The present invention relates to a method and apparatus for automatically assessing seed during the processing thereof, by: a) taking a sample of seed; b) visualizing a sub-population of the sample; c) determining which of the separate seeds of the sub-population is an assessable seed; d) measuring on at least a part of the assessable seeds a parameter from which can be derived whether the seed has the desired quality; e) subject to the parameter value found in step d) adding the value to a total value for good seeds or a total value for empty seeds; f) optionally repeating the steps from step c) until the total sample is analyzed; and g) optionally repeating the steps from step a). The method and apparatus are particularly suitable for the analysis of grass seed, wherein use is made of the fact that grass seed is translucent. Using this translucency it can be determined whether the grass seed is good or empty.

Description

METHOD AND APPARATUS FOR THE QUALITY ASSESSMENT OF SEED

The present invention relates to a method and apparatus for assessing the quality of a batch of seed during the processing. The invention is particularly suitable for assessing grass seed. Grass seed is applied on extensive scale everywhere in the world, but particularly in the western countries. The processing of grass seed, such as for instance the purifying thereof, has become increasingly more efficient and larger-sale due to mechanization and automation of the processing equipment. This makes more and different demands of the quality control of the end product and of the product during the treatments and of the quantity of good product in the waste flows. Where once the quality was assessed per individual grower batch, now diverse grower batches are combined and the thus obtained bulk further processed. The drawback to such large batches is that quality controls at the finish produce great wastage when a quality norm is not achieved. There is therefore a clear need for another form of rapid quality control which can already take place during the processing of the seed. It is important herein that practically the same values must be found as in purity determination on laboratory scale. An advantage of such a desired on-line checking is that, when a quality problem is already ascertained during the processing, such as for instance purifying of the seed, steps can still be taken during this processing to influence the treatment process, whereby the quality of the end product can still be acceptable. On-line monitoring of the waste flows can reduce the quantity of good product in the waste .

It is the object of the present invention to provide a method and apparatus with which the above stated objectives are realized for seeds in general and grass seed in particular. This is achieved for seed in general by the invention with a method for automatically assessing the seed, comprising the steps of: a) taking a sample of seed; b) visualizing a sub-population of the sample; c) determining which of the separate seeds of the sub-population is an assessable seed; d) measuring on at least a part of the assessable seeds a parameter from which can be derived whether the seed has the desired quality; e) subject to the parameter value found in step d) adding the value to a total value for good seeds or a total value for empty seeds; f) optionally repeating the steps from step c) until the total sample is analyzed; and g) optionally repeating the steps from step a) . A method according to the invention which is particularly suitable for assessing the quality of a batch of grass seed comprises the steps of: a) taking a sample of grass seed; b) spreading the sample on a transparent conveyor belt; c) illuminating the sample through the conveyor belt; d) visualizing a sub-population of the sample; e) determining which of the separate seeds of the sub-population is an assessable seed; f) calculating the value of a determined parameter of each assessable seed; g) determining of each assessable seed whether it has a sufficiently large core, and gl) in the case of an insufficiently large core adding the parameter value determined in step f) or a value derived therefrom to a total parameter value for empty seeds; or g2) in the case of a sufficiently large core adding the parameter value determined in step f) or a value derived therefrom to a total parameter value for good seeds; h) optionally repeating the steps from step d) until the total sample is analyzed; and i) optionally repeating the steps from step a) . The visualizing of a sub-population of a sample can for instance take place by means of a camera. The subsequent assessment of the recorded image of the sub- population of the sample preferably takes place by means of a computer provided with suitable software. In a preferred embodiment the method according to the invention is in fact based therefore on computerized image recognition. Image recognition is not new per se and is used for instance to check whether in a production line a particular component has been assembled in a product and whether the assembly route of that product can be continued. However, the use of image recognition techniques for assessing the quality of seeds, in particular grass seeds, during the treatment process is new.

The ability to assess seeds involves specific problems. In contrast to the recognition of components of a product, which generally have an unvarying appearance, this involves the recognition of natural products, no two of which are wholly identical. The computer will therefore have to "learn" which parts of the recorded image must be seen as seeds and what are contaminants. In addition, it must be possible to make a distinction between good and empty seeds . Only then can a correct quality assessment be obtained.

Recognition of the seed can take place by means of different criteria. In the case of translucent seeds such as grass seed and lettuce seed, use can be made of this property by illuminating the seed from below and then making an image thereof. Opaque seeds will have to be assessed by shape and/or color and can for instance be X-rayed. By means of the software and "instructing" of the computer it will be possible to enter the desired recognition patterns into the system for any seed. The criteria that can be used to distinguish seeds from contaminations, including other seeds, or to distinguish between good and empty (bad) seed are color, form and structure. Color can be used to identify diseases in and on the seeds. Form criteria can be used to find damage to seeds and the presence of husks and floral parts on the seeds. Degree of polishing, ripeness and dehydration of seed can be evaluated by means of the structure .

In a further preferred embodiment of the method for assessing grass seed, grass seed which is continuously illuminated from below passes beneath a camera which records continuously. The recordings are then analyzed using special software (for instance Video Frame Grabber™ and Image Processing Toolkit™, Neural Net- work™) . The analysis results in an image in which are located areas through which less light passes than through the original background (for instance a light plate or transparent conveyor belt) . These areas represent seeds or contaminants. Because the computer is adjusted such that it can recognize an assessable seed, it is capable of counting the number of assessable seeds. Objects smaller than assessable seed are counted as small contaminants. The recognition is based on shape and size. Seeds lying for instance on top of one another are hereby not taken into account.

Of the areas assessed as seed, differences in translucency are then registered. In the case of grass seed the caryopsis (core) will allow through less light than the husk. The ratio between the size of the two areas with a different translucency determined with the aid of surface scanning is a measure for the size of the core. By setting a minimum value for the ratio a distinction can be made between seeds with a sufficiently large core ("good seeds") and seeds with too small a core ("empty seeds") . For good grass seed it is generally the case that the surface area of the core amounts to at least 30% of the total surface area. Of each assessable seed the total surface area is then calculated and optionally converted to seed weight. Calculation of the weight may be important because in the current assessment methods quality is also expressed in weight ratios between good and empty seeds. The surface area or weight of empty seeds is added to a total value for empty seeds. The same is done for good seeds. The two total values represent the quality of the batch after completion of the analysis.

If desired, the system can be adjusted such that a comparison is also made between the total value for empty seeds and a predetermined threshold value. The same applies for the number of good seeds in the waste flows. When the threshold value is exceeded this can result in a signal and/or a feedback to the control of the processing device from which the samples originate. Prior to being taken into use for the method according to the invention the computer is adjusted to recognize grass seed. For this purpose grass seeds of the relevant species are presented to the system. The shape and size of the two types of seed are stored by the computer and an average with margins is determined therefrom. Any unknown grass seed falling within the margins of its species will then be later identified as belonging to this species. In addition to shape and size, the weight ratios of the known seeds are in the first instance also stored in the system. To this end good and empty seeds separated in conventional manner by means of a blow-pipe are presented to the image recognition system. This is necessary in order to be able to later calculate the weight on the basis of the surface area of unknown seeds .

The software is preferably provided with a neural network which is trained to recognize seed. This training can take place either by means of new recordings or by means of recordings stored in a database. Parameters are also entered into the system relating to the sensitivity of the neural network, the dimensions of the seed and the contaminants, and the boundary between good and empty seeds .

Preferably about 5000-7000 seeds are assessed per sample. Each image which is recorded contains for instance roughly 20 seeds. The software can for instance process two images per second.

At the end of the processing every batch is in principle still assessed as to quality by the official bodies designated for this purpose. The advantage of the method according to the invention is that the smallest possible safety margins need be observed due to a better control and checking of the quality. Safety margins are observed in order to prevent so-called repurification being necessary after checking by the official body. Repurification not only results in higher processing costs but good seed is moreover also lost therein. The present invention further provides an apparatus for performing the method. This apparatus comprises means for taking a sample, a device for recording an image of a sub-population of a sample, transporting means for guiding the sample past the image recording device and means for analyzing the recorded image .

As already stated above, the image recording means are preferably formed by a camera and the analysis means by a computer.

The transporting means can be formed for instance by a transparent, for instance milk white, conveyor belt which is preferably antistatic. If the belt were to become static due to the continuous circulating movement this would result in dust being attracted and thereby in deviations in the analysis. The apparatus can further be provided with means for generating a signal and/or means for feedback to the control system of the seed processing apparatus. An apparatus according to the invention can be incorporated in a conventional purifying line. Samples can then be taken at determined locations in the purifying line, optionally supplemented with samples from the waste flows in order to check whether too much good seed is disappearing during purification. If necessary, the process parameters of the purifying process can then be adapted on the basis of the results of the different samples .

The results of the analyses of successive images can for instance be plotted in a graph. The apparatus can comprise a plotter device for this purpose. The present invention will be further illustrated using the accompanying drawings in which corresponding reference numerals refer to corresponding components and in which: figures la and lb show a schematic overview of a purifying line having indicated therein the points at which samples are taken for processing in accordance with the method according to the invention; figure 2 shows a schematic view of an analysis station and the supply routes of sample material; and figure 3 is a perspective detail view of a part of the analysis station.

Figures la and lb show a schematic overview of a purifying line. The line is built up of a plurality of compartments, each comprising a particular type of purifying device. The non-purified batch of seeds is fed from a silo 1 and subjected to a first purification on a purifying machine 2 for a screen and air purifying. After two rubbers 3, 4 and a subsequent purifying machine 5 for a second screen and air purifying, a sample is taken for the first time from the seed flow at I, which sample will be analyzed according to the method of the present invention. The grass seed is guided to an intermediate bunker 6, whereafter, following a third purifying machine for screen and air purification 7, a sample is taken once again (II) . Following the screen and air purifier 7 the seed first enters a so-called splitter sorter 19. In such a device a separation is effected on the basis of shape. Objects with a round shape remain behind while elongate shapes, such as for instance grass seed, continue further. The splitter sorter separates the flow into two part -flows which enter parallel sorters 20, 21. The actual separation takes place in the sorters 20 and 21. After a screen purifier 22 the seed enters a storage bunker 23.

Samples are taken of the total purified product (III) and of the different waste flows (IV, V and VI) . Subject to the wishes of the user a sample can be taken from the seed flow at more or other points and analyzed. The transport of wholly or partially purified product (I, II and III) from the sample takers and of the waste flows (IV, V and VI) takes place by means of vacuum transport. Dust is hereby also removed from the waste to prevent fouling of the analysis station 8. From a small air purifier 9 for separating the sample and the dust, sample is dosed via a control slide 10 into the sample distributor 11. In order to obtain a representative sample a larger than necessary sample is taken, only a part of which is used. A vibrating chute 12 then provides the supply of the seed 13 to the transparent belt 14. The seed thereafter falls onto a distributing plate 18 which is slightly convex whereby the seeds are spread in width direction. Spreading in the length direction takes place due to the speed of the conveyor belt . Disposed under the belt is a light box 15 which illuminates the seed from below through belt 14. A camera 16 makes about 2 images per second and can record roughly 20 seeds per image. Once photographed the seeds fall into a collection bin 17 or the sample returns to the purifying line. This apparatus is further illustrated in detail in figure 3.

Claims

1. Method for automatically assessing seed during the processing thereof, comprising the steps of: a) taking a sample of seed; b) visualizing a sub-population of the sample; c) determining which of the separate seeds of the sub-population is an assessable seed; d) measuring on at least a part of the assessable seeds a parameter from which can be derived whether the seed has the desired quality; e) subject to the parameter value found in step d) adding the value to a total value for good seeds or a total value for empty seeds; f) optionally repeating the steps from step c) until the total sample is analyzed; and g) optionally repeating the steps from step a) .

2. Method for assessing the quality of a batch of grass seed during a treatment process, comprising the steps of : a) taking a sample of grass seed; b) spreading the sample on a transparent conveyor belt; c) illuminating the sample through the conveyor belt; d) visualizing a sub-population of the sample; e) determining which of the separate seeds of the sub-population is an assessable seed; f) calculating the value of a determined parameter of each assessable seed; g) determining of each assessable seed whether it has a sufficiently large core, and: gl) in the case of an insufficiently large core adding the parameter value determined in step f) or a value derived therefrom to a total parameter value for empty seeds; or g2) in the case of a sufficiently large core adding the parameter value determined in step f) or a value derived therefrom to a total parameter value for good seeds; h) optionally repeating the steps from step d) until the total sample is analyzed; and i) optionally repeating the steps from step a) .

3. Method as claimed in claim 1 or 2 , characterized in that a signal is given when the total (parameter) value for empty seeds exceeds a preset band width.

4. Method as claimed in claim 1, 2 or 3 , characterized in that as assessable seed is considered any seed having a predetermined shape and/or size.

5. Method as claimed in any of the claims 1-4, characterized in that the visualizing of a sub-population of the sample is effected using a camera.

6. Method as claimed in any of the claims 2-5, characterized in that the determined parameter of any assessable seed is the surface area of the seed and that the value derived therefrom is the weight of the seed.

7. Method as claimed in any of the claims 2-6, comprising of: a) taking a sample of a grass seed; b) spreading the sample on a transparent conveyor belt; c) guiding the conveyor belt with the seeds spread thereon beneath a camera; d) recording an image of a part of the conveyor belt passing under the camera at a determined moment; e) transmitting the image to a computer; f) counting the less translucent areas of the image using suitable software in order to obtain a value for the number of seeds for analysis; g) determining per less translucent area whether it is an assessable seed; h) determining, per area which is less translucent and classified as assessable seed, part-areas with a differing translucency in order to ascertain whether a core is present; i) classifying the area as "good seed" or

"empty seed" on the basis of the result of the determination of differences in translucency; j ) assigning the seed to a total value for good seeds or a total value for empty seeds subject to the result of step i) ; and k) optionally comparing the total value for empty and/or full seeds with a predetermined threshold value and generating a signal in the case the threshold value is exceeded.

8. Method as claimed in any of the claims 1-7, characterized in that the treatment consists of a purifying of the sample .

9. Apparatus evidently intended for performing the method as claimed in any of the claims 1-8, comprising means for taking a sample, a device for recording an image of a sub-population of a sample, transporting means for guiding the sample past the image recording device and means for analyzing the recorded image .

10. Apparatus as claimed in claim 9, characterized in that the image recording means are formed by a camera.

11. Apparatus as claimed in either of the claims 9-10, characterized in that the transporting means are formed by a transparent conveyor belt.

12. Apparatus as claimed in any of the claims 9-11, characterized in that the analysis means are formed by a computer.

13. Apparatus as claimed in any of the claims 9-12, further provided with means for generating a signal.

14. Apparatus as claimed in any of the claims 9-13, further provided with means for registering analysis data.