WO1985000657A1

WO1985000657A1 - Method and arrangement for the contact-free quality identification and structural description of, for instance, workpieces such as lengths of timber

Info

Publication number: WO1985000657A1
Application number: PCT/SE1984/000262
Authority: WO
Inventors: Tord Wadell
Original assignee: N. P.-New Products Nordinvent Investment Aktiebola
Priority date: 1983-07-22
Filing date: 1984-07-18
Publication date: 1985-02-14
Also published as: SE8304117D0; CA1220275A; FI853204L; SE8304117L; FI853204A0; EP0181332A1

Abstract

The object is scanned by means of optoelectrical sensors of at least two different types, being on the one hand sensors (2, 3, 9) with coarse resolution for the measurement of all or large parts of the object and on the other hand sensors (4-8) with fine resolution for the detailed measurement of the object. By means of the sensors of the first-mentioned type are determined the presence and the position of any variations in quality which are of interest in this context. The nature of any such variations is then determined by the sensors of the other type.

Description

TITLE OF THE INVENTION:

Method and arrangement for the contact—free quality identification and structural description of, for instance, workpieces such as lengths of timber

TECHNICAL FIELD:

The present invention relates to a method for the contact—free quality identification of, for instance, workpieces, such as the identification of different types of wood, the structural description of the fibre, and the determination of the properties and the quality of sawn and planed wood products for the purpose of preparing a product specification and for the positioning of processing tools used in subsequent stages of the manufacturing process.

The invention also relates to an arrangement for implementing the method.

_ B_A_C_KG_R_O_UN—D —__TO— THE INVENTION AND DESCRIPTION OF THE ₉

PRIOR ART:

The major proportion of the timber produced by sawmills and planing mills is currently inspected and assessed for quality by manual and visual means. The high rate of production at the present time calls for a very high Level of concentration from the timber graders, especially in connection with the classification of timber. It is difficult to maintain an even basis of assessment within strict limits when working manually for lengthy periods. A certain proportion of the structural timber which is produced is nevertheless classified by machine in respect of its strength by the physical bending of the lengths of timber as they are moving along or by a contact—free process of measurement using high—frequency radio waves, in particular microwaves, which are caused to pass through the length of timber. Under certain c rcumstances optical or electropotical equipment may be used to investigate the appearance of one side of the length of timber, for instance for the purpose of assessing the quality of the so-called lateral match. The information obtained in this way about the properties of the length of timber is relatively limited, however, and may be said to be restricted essentially to revealing the presence of defects rather than to describing their nature.

OBJECT OF THE INVENTION AND ITS HOST IMPORTANT CHARACTERISTIC FEATURES:

The object of the present invention is to provide an improved method for examining an object, for instance a workpiecε such as a Length of timber, by the contact—free measurement of said object, thereby providing a far more thorough and more accurate assessment of the characteristic features of the object. The invention was thus intended essentially to permit a sufficiently thorough examination of a length of timber to be carried out by the contact—free measurement of said timber for the result of measurement to be capable of being used in a quite detailed product specification and also of being used for the automatic guidance of a certain amount of processing, treatment or handling of the Length of timber, depending on the characteristics of said length of timber established by measurement.

The method proposed for this purpose in accordance with the invention and the arrangement are characterized in that information in respect of the visual character of at Least two different sectional areas or a number of different surfaces of the object and parts thereof is collected via optoelectrical sensor organs from two levels of scanning and measurement at coarse (low) and fine (high) resolution respectively.

It is possible in accordance with the invention to collect, store, analyze and compare information from the length of timber relating to at least one end surface and at least one lateral surface of said Length of timber. It is also possible, where appropriate, to collect, store and analyze information relating to all the surfaces of the length of timber.

The invention permits a precise determination to be made of practically every characteristic feature of the length of timber which it may be wished to know. It is particularly worthy of mention in this respect that the method in accordance with the invention can be utilized for the determinat on of the mechanical strength of the Length of timber. It may be important in this case for the information which is collected to include information in respect of the visual character of at Least one end surface of the Length of timber, preferably being at that end of the length of timber which is nearest the root.

With the aim of simplifying the equipment required for the storage and/or processing of the information relating to the object it is possible, prior to storing or analysing the collected or stored information, to divide it up into two or three different part quantities relating to separate parameters of each surface or parts thereof, in which case the actual quantity of information associated with this can be reduced prior to storage or analysis of same. As examples of such parameters, reference may be made to the structure of a surface, its form, or its geometry, and to surface defects on the Length of timber, for example knots or cracks.

The invention may be applied in practice for a variety of different purposes. For example, the method in accordance with the invention may be utilized in connection with the preparation of a product specification and to determine to which of a number of dimensional and/or quality classes a length of timber may be allocated, as well as the kind of wood of which it consists. The invention can in this case be applied to a timber grading plant so as to permit the fully— or semi—automatic control of said plant with the aim of reducing the need for intervention by the operator.

Other workpieces exist, however, in respect of which it may be wished to establish certain characteristic features for the purpose of specifying the nature of their further processing or of checking, for example final inspection. The widest application for the invention may thus be said to be in the areas of inspection and the determination of characteristics on the basis of a visual image and with the help of automatically operating devices. DESCRIPTION OF THE DRAWING:

The accompanying Figure shows a general view of the devices applied to the invention.

The invention is described below with reference to an embodiment which is best suited to the quality identification of timber. The indicated principles may, however, also be applied in other contexts. With reference to the Figure the measurement object, in this case a Length of timber, is identified by the reference designation 1 . Optoelectrical sensor organs 2—8 with filters and objectives are so arranged as to scan one of the flat sides 11 Clongitudinal section) of the length of timber, and sensor organs 9, 10 are so arranged as to be trained onto one of the end surfaces 12 Ccross section) of the length of timber. The optoelectrical sensor organs used for the longitudinal section are divided up into two groups comprising on the one hand two organs 2 and 3 having coarse Clow) resolution permitting general structural analysis and on the other hand a number of organs 4—8 having fine Chigh) resolution permitting detailed analysis. In a similar fashion the organs used for the cross section are divided up into one organ 9 having coarse resolution and one organ 10 having fine resolution.

The method is performed by scanning, preferably along the length or across the breadth of the length of timber, during continuous or intermittent movement. However, the sensor organs 4—8 and 10 providing fine resolution are so arranged as to be capable of movement in relation to the Length of timber 1 , so that each of them can be aimed at a specific area of the surface, this being the scanning area within a specially identified part of the length of timber. On the other hand, the . sensor organs 2, 3 and 9 providing coarse resolution need not be capable of individual movement, but may capture the length of timber as it is being transported past the organs at a given moment along its path. Because the surface which is to be scanned is much Larger in its longitudinal section 11 than in its cross section 12 the surface in question has, in fact, been divided up between two of the aforementioned sensor organs, these being 2 and 3 , whereas the cross section is scanned by only a single sensor organ, this being the organ 9 . In order to represent the possibility of movement by the sensor organs -4—8 and 10 , these have been drawn with sliding rails 13 and 14 . What is important in this context, however, is not the manner in which the Length of timber which is to be identified is caused to move past the sensor organs, but the fact that such relative movement actually takes place, and that the object can be scanned not only in its entirety by the sensor organs having coarse resolution, but also by the sensor organs having finer resolution. This can be made to happen in this case by causing only the sensor organs or only the object to move or, as shown here, by causing both the object and the sensor organ to move.

The fundamental idea behind the method in accordance with the invention is that it is possible with the help of a device which corresponds to that specified here initially to identify any areas on the object which appear in the form of marks, either which call for a more detailed examination to be made for possible quality defects such as physical damage, or which are particularly suited to the determination of a given grade of quality for the length of timber, such as the type of wood in this case.

Different types of quality defect can thus occur in Lengths of timber, said defects manifesting themselves as marks in the form of darker areas. These marks may, however, represent various types of variation in quality, and a more detailed examination must be made. The use of coarse resolution permits the entire length of timber to be scanned easily over its large surface areas, enabling the number and extent of said variations in quality to be determined, although their specific character cannot be determined with sufficient reliability at coarse resolution. In order to be able to do this, the one or more sensor organs having fine resolution are utilized to provide a detailed analysis of the areas in question.

As far as concerns the aforementioned quality determination, although not the inspection for possible variations in quality, there are present on a length of timber areas of particularly distinct graining, said areas being more suitable for determining the type of wood in the length of timber than other areas of more indifferent graining. These more strongly grained areas can be identified by means of the sensor organs with coarse resolution, and a detailed examination permitting the type of wood to be determined can then be made by the aforementioned sensor organs with fine resolution.

The advantages resulting from the ability to identify the type of wood do not require to be discussed in any greater detail, although it should be obvious that it is generally desirable when processing wood of mixed types to be able to distinguish between these in terms of differences in price and area of application. As far as concerns the wish to be able to distinguish between types of variation in quality, attention is drawn to the fact that Lengths of timber may contain variations which are of no consequence from the point of view of strength, for example sap discolouration, and which do not, therefore, affect its use as structural timber, but which make the length of timber unsuitable for use in certain types of furniture, for instance. Damage of other kinds, such as rotting, cracks and streaks of pith, may be of such significance to the strength characteristics that account must be taken of them when selecting the timber and cutting it to size for structural use. Certain areas of damage may be so serious that the timber must be cut to size in such a way that the sections in which damage is present are eliminated. Other types of damage may influence the use to which the timber is put, as previously described, and may even affect the price. Phenomena such as knots are generally acceptable to a certain extent in timber, although not in such numbers as to jeopardize its strength. It will be appreciated, therefore, that it is extremely important to find ways of examining certain areas on the surface of the timber by general scanning before proceeding to a more detailed inspection of the character of the apparent phenomena. In a similar fashion objects other than Lengths of timber can similarly be processed by means of general scanning followed by the detailed inspection of any areas which are of interest in the particular context. Workpieces can thus be scanned in this way so that the surface coating can be inspected by the general scanning process, with the character of any surface defects then being determined by the detailed scanning. The workpieces can/examined in this way before being passed to other stations, for example in order to identify the need for minor adjustments, for total renovation or for scrapping.

Another example of the application of the invention is for the grading of natural products ranging from animal skins to fruit. The quality of natural products may be uneven, and various types of damage may be present. It is usual to classify the product into one of a number of price categories and/or to allocate it to a particular use. For example, animal skins with large areas from which certain types of damage are absent are used in items having a large surface area, whereas those pieces which have been cut away from the sides or which are in the form of small pieces taken from between areas of damage may be used for so— alled 'patchwork'; in the case of fruit, for example, it should be obvious that fruit is classified into different price categories in accordance with damage of a cosmetic nature, whereas damage of a type which affects its use and keeping properties will result in the fruit being destroyed or cut up for canning.

As will have been appreciated from the above, the method in accordance with the invention will, in principle, be applied in accordance with the following plan:

1. Scanning of the entire object at coarse resolution;

2. Recording of areas requiring more detailed examination; this may include, for example, the identification of those areas presenting a variation in reflected Light Cdark areas);

3. Once the Location of those areas which require more detailed examination has been indicated, this information is then used to guide to those areas one or more of the detailed scanning organs having finer resolution;

4. The last—mentioned sensor organs compare the perceived image with images contained in the memory for the identifcation of the characteristics, for example the quality, of the area which has been scanned in detail;

5. With the help of the above determination of the level of quality in a given case, together with the position, the size and the distribution of what has been perceived, a decision in respect of the nature of the further processing is made in accordance with a plan stored in the memory.

In other words a positional determination is obtained initially from the first—mentioned sensor organs with coarse resolution, said sensor organs being connected to control devices for guiding the remaining sensor organs for the purpose of the detailed scanning. The latter organs with the finer resolution are, on the other hand, so arranged as to produce a structural analysis of the scanning area in question, for which purpose they are connected to analysis organs which are in turn connected to a memory in which are stored data in respect of those structures which may conceivably occur.

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Claims

— rPATENT CLAIMS

1. Method for the contact—free quality identi ication and structural description of objects, for instance workpieces, such as lengths of timber, c h a r a c t e r i z e d in that the 5 object is scanned by means of optoelectrical sensor organs of at least two different types, being on the one hand sensor organs (2, 3, 9) with coarse resolution for the measurement of all or large parts of the object, and on the other hand sensor organs (4—8) with fine resolution for the detailed measurement of the 10 object, with the presence and the position of any variations in quality which are of interest in this context being determined by means of the sensor organs of the first— entioned type, whereupon the nature of any such variations is then determined by means of the sensor organs of the other type. 15

2. Method in accordance with Patent Claim 1, c h a r a c t e r i z e d in that the measurement by means of the first—mentioned sensor organs (2,

3, 9) is used to determine the presence and the position of areas of interest for the detailed measurement and for the guidance of the last—mentioned 20 scanning by the sensor organs of these identified areas, whereas said other sensor organs (4—8) are used to determine the nature of any variations in quality by means of structural analysis utilizing a storage unit containing details of interesting structures which may conceivably occur. 25 3. Method in accordance with Patent Claim 2 for the contact—free ident f cation of the type of the wood, the structural description of the fibre, and the determination of the properties and the quality of timber which is to be provided with a product specification and is subsequently to undergo further 30 processing, c h a r a c t e r i z e d in that details of the^" visual character of the length of timber (1) are collected via optoelectrical sensor organs with physical or mathematical filtering C2—10) and are converted in respect of at least one longitudinal section (11) and at least one cross section (12) 35 from each of two levels of scanning and measurement, these being level 1, the macro level C13—14), at coarse (lower) resolution permitting general structural analysis to be performed in respect of the biological and technical properties of the entire surface of the longitudinal section (11) and the surface of the cross sec¬ tion (12) , making use simultaneously for this purpose of level 2, ^" the micro level (15 and 16) , at fine (higher) resolution permitting random detailed analysis of the structure of the fibre via test surfaces (17-21 and 22) , with each of the results from the diffe¬ rent levels being interpreted interactively and in parallel for the analysis of the direction of the fibres and other characteristic features of the entire workpiece in a central computer (23) , with the identification of the type of the wood being provided by the transformation technique.

4. Arrangement for the contact-free quality identification and structural description of objects , for example workpieces , such as lengths of timber, c h a r a c t e r i z e d in that the arrange¬ ment comprises optoelectrical sensor organs of at least two diffe¬ rent types for scanning the object, being on the one hand sensor organs (2, 3, 9) with coarse resolution for examining all or large parts of the object and on the other hand sensor organs (4-8) with fine resolution of the detailed examination of the object, in that the first-mentioned type of sensor organ is so arranged as to identify the occurrence and the position of any variations in quality which are of interest in the particular context, and in that the second type of sensor organ is so arranged as to then examine the nature of any such variations .

5. Arrangement for the contact-free quality identif action and structural description of objects, for instance workpieces , such as lengths of timber, with the object being scanned on the one hand by means of optoelectrical sensor organs (2, 3, 9) of a first type for scanning all or large parts of the object, and on the other hand by means of optoelectrical sensor organs (4-8) over small areas for the detailed measurement of the object within said areas , c h a r a c t e r i z e d in that the sensor organs (2, 3, 9) or the first type are so arranged as to record the presence and the position of variations in quality and are connected to arrangements providing guidance of the sensor organs (4-8) of the second type for the scanning of those areas whose positions

p.vπ have been determined, whereas the sensor organs of the second type are so arranged as to scan the structure of said area with fine resolution and are connected to a storage unit in which are contained details of interesting structures which may occur in this context, in addition to which processing arrangements are provided for the purpose of comparing the structural image re¬ corded by the sensor organs and the structural images contained in the memory for thr purpose of determining the nature of the scanned structure.

6. Arrangement in accordance with Patent Claim 5 for the contact-free identif action of the type of the wood, the structural description of the fibre, and the determination of the properties and the quality of the timber and, on the basis of this , for the control of the positioning of processing tools in subsequent manu- facturing processes for sawn and/or planed wood products, c h a r a c t e r i z e d in that a central computer (23) and a number of optoelectrical sensor organs (2-10) , having on the one hand individual microprocessors , on the other hand physical or mathematical filtering and on the other hand different objectives for the measurement process , scan and convert the visual charac¬ ter in respect of at least one longitudinal section (11) , being a flat side, and at least one cross section (12) , being the end sur¬ face, from two levels of resolution - one being the macro level at coarse (lower) resolution permitting general structural ana- lysis , and the other being the micro level at fine (higher) reso¬ lution permitting the random detailed analysis of the structure of the fibre.

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