CA1080324A - Electro-optical monitoring system - Google Patents
Electro-optical monitoring systemInfo
- Publication number
- CA1080324A CA1080324A CA266,077A CA266077A CA1080324A CA 1080324 A CA1080324 A CA 1080324A CA 266077 A CA266077 A CA 266077A CA 1080324 A CA1080324 A CA 1080324A
- Authority
- CA
- Canada
- Prior art keywords
- view
- field
- detector means
- detector
- zone
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired
Links
Classifications
-
- 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
- G01B11/08—Measuring arrangements characterised by the use of optical techniques for measuring diameters
- G01B11/10—Measuring arrangements characterised by the use of optical techniques for measuring diameters of objects while moving
- G01B11/105—Measuring arrangements characterised by the use of optical techniques for measuring diameters of objects while moving using photoelectric detection means
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
- B27B31/00—Arrangements for conveying, loading, turning, adjusting, or discharging the log or timber, specially designed for saw mills or sawing machines
- B27B31/06—Adjusting equipment, e.g. using optical projection
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16P—SAFETY DEVICES IN GENERAL; SAFETY DEVICES FOR PRESSES
- F16P3/00—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body
- F16P3/12—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine
- F16P3/14—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine the means being photocells or other devices sensitive without mechanical contact
- F16P3/144—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine the means being photocells or other devices sensitive without mechanical contact using light grids
-
- 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
- G01B11/27—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes
- G01B11/272—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes using photoelectric detection means
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Forests & Forestry (AREA)
- Wood Science & Technology (AREA)
- Control Of Conveyors (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Geophysics And Detection Of Objects (AREA)
- Closed-Circuit Television Systems (AREA)
- Optical Communication System (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
Abstract
ELECTRO-OPTICAL MONITORING SYSTEM
Abstract of the Disclosure A system for viewing a zone to detect the presence of an article carried therein on a conveyor. In one embodiment, the system includes a laser source which projects a line-beam of coherent light toward the zone, which beam is intersected, along a length thereof, by the planar field of view of a reflection detector whose view-plane contains the beam. In another embodi-ment, the system uses a laser source which projects a planar beam of coherent light which is intersected by the field of view of a reflection detector whose view-field has both length and breadth dimensions where it intersects the laser beam. In both embodiments, the region of intersection of the laser beam and the detector's field of view is spaced from the conveyor.
1.
Abstract of the Disclosure A system for viewing a zone to detect the presence of an article carried therein on a conveyor. In one embodiment, the system includes a laser source which projects a line-beam of coherent light toward the zone, which beam is intersected, along a length thereof, by the planar field of view of a reflection detector whose view-plane contains the beam. In another embodi-ment, the system uses a laser source which projects a planar beam of coherent light which is intersected by the field of view of a reflection detector whose view-field has both length and breadth dimensions where it intersects the laser beam. In both embodiments, the region of intersection of the laser beam and the detector's field of view is spaced from the conveyor.
1.
Description
1 ~ 8~ 3~ ~
Background and Summary of the Invention This invention pertains to a system for viewing a selected zone to detect the presence of an article in the zone.
More particularly, it pertains to such a system which utilizes a beam of light, such as that produced by a laser, which beam is intersected by a defined wide-expanse field of view of a reflec-tion detector, with the region of intersection of these two things lying within the selected zone.
There are various applications in which it is desired to provide an automatic monitoring or detection system for noting the presence of an article in a selected zone. For example, it is typical in many sawmills to note the presence of a log carried either sideways or endwise into such a zone for the purpose of producing some control function, such as the operation of a saw.
~' Typical detection systems include a source of light, "
such as a laser, which projects a beam toward a conveyor on ' ' which an article is carried, with a detector placed in the path of the beam so as to be able to note any interruption in the beam, thus to indicate, presumably, the presence of an article.
This type of system, however, is sub;ect to severe disadvantages, in that under operating conditions, it is often the case that various kinds of debris, other than an article of interest, are carried on the conveyor and interrupt the light beam, just as 1 the desired article would. Furthermore, passage of conveyor '~ parts or other structure across such a beam has often been the cause of false'responses.
A general object o~ the present invention is to provide a unique monitoring system which'completely avoids these diffi-' 30 culties in an extremely practical and satisfactory manner.
According to one'embodiment of the'proposed invention, the system includes a laser source which projects a line-beam of .
Background and Summary of the Invention This invention pertains to a system for viewing a selected zone to detect the presence of an article in the zone.
More particularly, it pertains to such a system which utilizes a beam of light, such as that produced by a laser, which beam is intersected by a defined wide-expanse field of view of a reflec-tion detector, with the region of intersection of these two things lying within the selected zone.
There are various applications in which it is desired to provide an automatic monitoring or detection system for noting the presence of an article in a selected zone. For example, it is typical in many sawmills to note the presence of a log carried either sideways or endwise into such a zone for the purpose of producing some control function, such as the operation of a saw.
~' Typical detection systems include a source of light, "
such as a laser, which projects a beam toward a conveyor on ' ' which an article is carried, with a detector placed in the path of the beam so as to be able to note any interruption in the beam, thus to indicate, presumably, the presence of an article.
This type of system, however, is sub;ect to severe disadvantages, in that under operating conditions, it is often the case that various kinds of debris, other than an article of interest, are carried on the conveyor and interrupt the light beam, just as 1 the desired article would. Furthermore, passage of conveyor '~ parts or other structure across such a beam has often been the cause of false'responses.
A general object o~ the present invention is to provide a unique monitoring system which'completely avoids these diffi-' 30 culties in an extremely practical and satisfactory manner.
According to one'embodiment of the'proposed invention, the system includes a laser source which projects a line-beam of .
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coherent light toward a selected zone, which beam is intersected, along a length thereof, by the planar field of view of a re~lec-tion detector whose view-plane contains the beam. The region of intersection of the beam and the field of view is referred to as a sensitivity region, and this region is positioned so that it is spaced appropriately from any conveyor or other support means for an article in the zone.
In general terms, the present invention provides an electro-optical monitoring system for noting in an observation zone the presence of a solid and essentially non-transparent article, particularly a log to be fed into a saw, comprising at least one means for projecting into said zone a beam of optical radiation, and at least one detector means sensitive to said radiation, wherein said at least one projecting means is adapted to generate a beam which, when viewed from at least one side, has substantially the appearance of a straight line, said at least one detector means is a reflection detector means constructed to have a defined field of view broadening in the direction ; away from the detector means and intersecting said beam along a finite length thereof, said intersection producing a sensitivity region of pre-selected extension and location in said zone, and said at least one projecting means and at least one detector means being oriented relative to one another so that the latter is unable to view directly radiation projected by the former and only can perceive radiation emitted from the former after reflection on a solid article positioned within said sensitivity region. ~ -; Preferably, said beam, when viewed from any side, appears as a substantially straight line, and the field of view of said detector means lies in a plane containing said beam so that an essentially line-shape sensitiuity region is obtained.
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- ~LQ8V3Z4 The apparatus may further include means adjacent said zone for supporting an article in the zone, said beam then projecting toward said support means, and said sensitivity region being spaced from said support means. The means for projecting a beam preferably comprises a laser.- The beam may be essentially planar, and the field of view of said detector means, where it intersects said beam, may as well have length and width within the plane of the beam.
These and other objects and advantages which are attained by the invention will become more fully apparent as the description which now follows is read in conjunction with ~he accompanying drawings.
Description of the Drawings Fig. 1 is a schematic view of a log-positioner in a '' .. . .
- 3a - - ~
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sawmill in connection with which one embodiment of the system of the present invention is used.
Fig. 2 is a side view taken from the left side of Fig.
1. ..
Fig. 3 is a schematic diagram of a detector used in the system of Figs. 1 and 2.
Fig. 4 is a schematic end view of a log-scaling station in a sawmill in connection with which another embodiment of the instant invention is used.
Fig. 5 is a side view of the station o~ Fig. 4.
Detailed Description of the Invention Turning now to the drawings, and referring first to Figs. 1 and 2, ind:Lcated generally at 10 is a positioning station, or zone, in a sawm:Lll where logs are to be positioned prior to their being fed endwise into a saw. Provided for carrying logs endo into this station, and ultimately into a saw, is a movable carriage 12. A log 14 is shown on the carriage in the station.
Provided on one side of the carriage is a laterally shiftable positioner including upright independently movable arms 16 which may be shifted toward and away from the carriage for the purpose of aligning a log thereon as desired. Shown schematically at 18 in Fig. l~ as being associated with the positioner arm seen in this figure, is a rack and pinion drive which i8 driven by an electric motor 20. ~ like drive and motor are provided for the other ar~. The motors are started and stopped through suitable conventional control apparatus, such as . ~
. , .
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, . . . . . .
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that represented in block form at 22.
What has been described so far is entirely conventional. --What is intended with this apparatus is that logs, such as log 14, are brought into station 10 on carriage 12 so that they may be engaged by arms 16 of the positioner. Prior to feeding such logs endwise into a saw, it is desired that each log ~e posi-tioned laterally on the carriage, whereby its side which is opposite arms 16, extends no further than a selected plane, such as that shown represented by line 24 in Fig. 1. When a log is so positioned, it is in proper lateral alignment for feeding into the mentioned saw.
Pro~ided according to the present invention for assist-ing in so positioning logs is a monitoring system including a pair of modulated laser sources 26, 27 and a pair of reflection detectors 28, 29 which are sensitive to the beams emitted by the sources. Source 26 and detector 28 are associated with the right-hand arm 16 in Fig. 2, and source 27 and detector 29 are ~, associated with the left-hand arm in this figure. The two sources are identical. Such also is true with respect to the detectors.
Source 26 includes a conventional laser 30 suitably coupled to a conventional amplitude modulator 32 which operates herein at a frequency of about 2000 Hz. The reason for using a modulator will be explained more fully shortly. Source 26 herein, when operating, projects along a line 33 (see Fig. 2) a modulated linear laser beam which occupies previously mentioned plane 24. Source 27 projects a similar beam along a line 35 (see Fig. 2? which also occupies plane 24.
Referring to Fig. 3 along with Figs. 1 and 2, detector 28, inside its housing, includes a lens 34, a relatively large-area photodet~ctor 36 which is coupled electrically through a modulating signal-pass filter 38 ~ith an output amplifier 40.
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All of these components in the detector are conventional.
Filter 38, in effect, "tunes" the detector for being sensitive only to reflected laser radiation which is modulated at the frequency of modulator 32. Thus, it will be seen that the reason for using and detecting a modulated laser beam is to increase the sensitivity of the overall system by making the system in effect, reject all other sources of optical radiation.
Provided between photodetector 36 and lens 34 are a field-of-view mask 42, and in front of this, a band-pass optical filter 44. Filter 44 is selected to pass, essentially, only light coming from laser 30. Provided in mask 42 is an elongated thin linear slot 42a, the purpose for which will be explained shortly.
As is clearly implied by its name, mask 42 defines the fieId of view of detector 28. With this mask being provided with slot 42a, the field of view of detector 28 is substantially planar. This field of view is indicated at 46 in Figs. 1 and 2, and it will be noted that the fieId has a wide expanse where it is adjacent station 10. Further describing the situation which exists, field of view 46 occupies a plane parallel to that of Fig. 1, and contains previously mentioned line 33. It will be noted that the upper reach of the field of view intersects line 33 at 46a and that the lower reach of the field intersects the line at 46b. Attention should especially be called to the fact that intersection point 46b is disposed above the top of carriage 12. Thus, the whole region, which is a linear region, wherein field 46 and line 33 intersect is spaced above the carriage. -This intersection region is referred to herein as a sensitivity region.
Detector 29 has a field of view 47 which is like field 46 except that it contains line 35. This field is show~ in Fig.
2. It will be noted that field 47 has an upper intersection 6.
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~0803'~4 with line 35 at 47a, and a lower intersection with this line at 47b. Point 47b is at substantially the same elevation above conveyor 12 as point 46b.
Referring again particularly to Fig. 3, a feature of the detector 28 which should be noted is that mask 42 may be laterally repositioned within the housing of the detector. The design of the specific means for allowing this is not important~. ' herein, and hence is not shown. It will be evident that reposi-tioning of the mask will relocate slot 42a, so as to shift the field of view of the detector. This feature is a desirable one in that it enables quick mounting of the detector in place, and ready fine ad~ustment of the location of the field of view so as.' to select precisely the region of intersection of this field and.
a laser beam like that which is projected from source 26. : ' The output of amplifier 40 in detector 28 is coupled ' to conventional control apparatus represented in block form at '~.
48. Control apparatus 48 is in turn connected to previously mentioned motor controller 22. The amplifier in detector 29 corresponding to amplifier 40 i8 similarly connected to control apparatus 48. The functioning of apparatus 48 will be explained shortly.
Explaining now how the system of the invention which has been described so far performs, sources 26, 27 and detectors 28, 29 are energized. As a conse.quence, the sources project , line-beams of modulated laser light along lines 33,.35 in plane ; 24. The detectors view these beams.in the planar fields of view shown at 46, 47, for the'purpose'of detecting any reflected l laser light. Light other than that produced by the lasers will .' be re~.ected by the'detectors,.both because of the presence of amplitude'~odulation which.'is.used with respect to the'beams, and because of the presence'of.band-pass optical filters in the ".
detectors. ' ~.
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A log is carried endwise into station 10 on conveyor 12 and is stopped so that it may be engaged by positioner arms 16. A suitable command is given to turn on the motors for the positioner arms, whereupon these arms advance toward the log across the conveyor.
It will typically be the casP that one end of a log '.
will be moved to where it intersects plane 24 before this happens with respect to the other end of the log. Assuming that what is shown as the right-hand end of log 14 in Fig. 2 is first to .' intersect plane 24, when this occurs, the part of the log which '~
: intersects the plane, it will be seen, lies within the field of view of detector 28, and also intersects the beam of light being ~-projected from source 26. As a consequence, light will be reflected to detector 28 which will then produce a control ' signal from amplifier 40 which, through the actions of control ' apparatus 48 and motor controller 22, shuts off motor 20.
The other positioner arm which is moving the left end of the log in Fig. 2 toward plane 24 will continue to operate until this end also intersects the plane. Like action will then take place with re~pect to the motor operating this other posi-tioner arm. More particularly, such intersection of plane 24 will result in light being reflected to detector 29 which, again through the combined actions of apparatus 48 and controller 22, will shut off the motor provided for.this other arm.
Log 14 is then properly positioned for advancement into a saw.
It will especially be noted th.at because of the way in which the'ields of.view o the'de.tectors are'arranged to inter-sect the'line-beams of light from.the'laser sources, any debris 3~ which ~a~ be'carried on.conveyor 12 will not produce any reflected '-:' light which mi:ght be.'det'ected by .t.he. de.tectors to.pro.duce false control signals. 'Also,:it will be no.ted that the'sensitivity .
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~08~3;24 regions defined by the lengths of intersections of the fields of view and the laser beams are suitably spaced from the conveyor, whereby movement of the conveyor parts will not effect any false control signals.
Let us consider now the embodiment of the invention illustrated in Figs. 4 and 5. Shown herein generally at 50 is a station for scaling logs, through which station logs, such as log 52, are transported by an elongated conveyor 54. Suitably disposed above conveyor 54, in a housing 56, is a laser source 58 including a laser 60 which is like previously described laser 30, and an amplitude modulator 62 which is like previously described modulator 3Z. Also included in source 58, within housing 56, are a parabolic mirror 64, a rotary-mounted mirror 66, and a motor 68 which is drivingly connected to mirror 66 to ' rotate'the same.' Mirror 66 is rotatable about a horizontal axis ~'' shown at 70--this a~is lying in the'same horizontal plane con-taining laser 60 and modulator 62.
The reIative positions of the laser, modulator and rotating mirror in Figs. 4 and 5 are shown only schematically in these figures. The laser and modulator are positioned so as to project a modulated laser beam toward the inclined surface 66a of mirror 66, with this beam lying in the same horizontal plane containing axis 70. With rotation of the mirror, in the direc-tion of arrow 72 seen in Fig. 4, the rotating mirror scans the beam of the laser along and across the'parabolic surface of mirror 6h. The direction of traveL of the scanned beam across the'mirror i8 indicated by arrow 74 in Fig. 4.
With operation of source'58, there~ore, what is produced i8 a subatantially vertical, planar, swept beam of laser light ~ 30 which'occupies the'vertical plane'sho'wn at 76 in Fig. 5, and '~ which'has thé'width indicated as ~ in Fig. 4. 'It will be seen that thi's planar beam is directed t~ard conveyor 54, and extends ~... . . . . . .
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~3133~
a considerable distance on opposite sides of the conveyor.
Also included in the monitoring system used in conjunc- -tion with scaling station 50 are two detectors 78, 80 which are ~-each extremeIy similar in construction to previously described detector 28, except that the fieIds of view of detectors 78, 80 are pyramidal rather than planar. The configuring of such fieIds of view for these detectors may readily be accomplished by providing them with masks, such as mask 42_, in which a generally rectangular aperature is provided for defining such fieIds of view. The'fields of view of detectors 78, 80 are --shown at 82, 84, respectiveIy.
As can be seen in Fig. 4, detectors 78, 80 are located above and on opposite sides of conveyor 54, and look downwardly at angles toward the conveyor. As can be seen in Fig. 5, the detectors are located longitudinally to one side of source 58 whereby they look downwardly at an angle toward conveyor 54 in the region of plane 76.
It will thus be apparent that the fields of view of the detectors, where these fields intersect plane 76 (which is the'plane of the scanned laser beam) produce regions of intersec-tion which have both length and breadth dimensions in plane 76. ':
Such a region of intersection, called a sensitivity region, is shown generally at 86 in Fig. 5. An important consideration herein is that the'detectors are'also oriented whereby no por- '' tions of their fields of view in the region of intersection with plane 76, touch conveyor 54. 'Further, these regions of intersec- ' tion are located above'the'top surface of the conveyor.
In the'system shown in Figs. 4 and 5, it is intended '~
that output signals from the'det'ectors be'used to compute log diameter along the'length'of a log such as log 52. 'The'exact way in which'such computations are'performed is no part of the present invention. 'However, reference'may be made'herein to 10. :`
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1~ 80 32 ~
u.s. Patent No. 3,997,269 to Clifford ~. Moulton for "Scaling Apparatus With Linearization compensation". This patent discloses apparatus usable in the present sYStem to reIate the output signals produced by detectors 78, 80 to the -angular position of mirror 66 with respect to mirror 64, whereby log diameter dimensions may accurately be determined.
Regardless of how the output signals produced by detectors 78, 80 are specifically used, the system shown in Figs. 4 and 5 performs with mirror 66 scanning a beam of laser light in plane 76, which beam is viewed in the fields of view of detectors 78, 80 to look for any reflections. Just as was the ' case with the'system shown in Figs. 1 and 2, wood chips or other debris carried on conveyor 54 will produce no false output signals. Further, movement of the conveyor parts will not produce such a signal. The only event which will result in a ~' signal, whi'ch will be a proper signal, is the presence in a region of intersection of a field of view 'of one'of the detectors and plane 76 of an object which'reflects the scanned laser beam.
The arrangement of the detectors, as has been explained, is such that this event will only occur when an article of interest, such as log 52, intersects one of these regions.
It will thus be apparent that a very simple and effec-tive system is proposed by the in~ention for monitoring the presence o~ an article at a selected location. The system can be used also for measuring dimensions. By utilizing beams of optical radiation, such as those'described, which beams are '~
'~ intersected by the angularly disposed, defined wide-'expanse fields of view of optical detectors, sensitivity regions are ~ `
defined which may be geometrically spaced so as to avoid false~
signal problems which have'characterized previously available scanning or monitoring equipment. 'It will also be'apparent that JP~;' 11. :
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a system embodying the invention may take a number of different forms and may readily be incorporated in various different kinds of apparatus. Further, by equipping a detector in the system with a shiftable mask, such as that described herein, placing of a system becomes an extremely simple operation, since fine adjustments for positioning the desired region of sensitivity may be made simply by shifting the position of the mask in the detector. It will be recognized, of course, that fields of view may be specially configured to suit different applications. :
While two embodiments of the invention have been described herein, it is appreciated that other variations and modifications may be made without departing from the spirit of the inventlon.
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coherent light toward a selected zone, which beam is intersected, along a length thereof, by the planar field of view of a re~lec-tion detector whose view-plane contains the beam. The region of intersection of the beam and the field of view is referred to as a sensitivity region, and this region is positioned so that it is spaced appropriately from any conveyor or other support means for an article in the zone.
In general terms, the present invention provides an electro-optical monitoring system for noting in an observation zone the presence of a solid and essentially non-transparent article, particularly a log to be fed into a saw, comprising at least one means for projecting into said zone a beam of optical radiation, and at least one detector means sensitive to said radiation, wherein said at least one projecting means is adapted to generate a beam which, when viewed from at least one side, has substantially the appearance of a straight line, said at least one detector means is a reflection detector means constructed to have a defined field of view broadening in the direction ; away from the detector means and intersecting said beam along a finite length thereof, said intersection producing a sensitivity region of pre-selected extension and location in said zone, and said at least one projecting means and at least one detector means being oriented relative to one another so that the latter is unable to view directly radiation projected by the former and only can perceive radiation emitted from the former after reflection on a solid article positioned within said sensitivity region. ~ -; Preferably, said beam, when viewed from any side, appears as a substantially straight line, and the field of view of said detector means lies in a plane containing said beam so that an essentially line-shape sensitiuity region is obtained.
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- ~LQ8V3Z4 The apparatus may further include means adjacent said zone for supporting an article in the zone, said beam then projecting toward said support means, and said sensitivity region being spaced from said support means. The means for projecting a beam preferably comprises a laser.- The beam may be essentially planar, and the field of view of said detector means, where it intersects said beam, may as well have length and width within the plane of the beam.
These and other objects and advantages which are attained by the invention will become more fully apparent as the description which now follows is read in conjunction with ~he accompanying drawings.
Description of the Drawings Fig. 1 is a schematic view of a log-positioner in a '' .. . .
- 3a - - ~
:
.- .. : -. . . . . . . . . -~08~33~
sawmill in connection with which one embodiment of the system of the present invention is used.
Fig. 2 is a side view taken from the left side of Fig.
1. ..
Fig. 3 is a schematic diagram of a detector used in the system of Figs. 1 and 2.
Fig. 4 is a schematic end view of a log-scaling station in a sawmill in connection with which another embodiment of the instant invention is used.
Fig. 5 is a side view of the station o~ Fig. 4.
Detailed Description of the Invention Turning now to the drawings, and referring first to Figs. 1 and 2, ind:Lcated generally at 10 is a positioning station, or zone, in a sawm:Lll where logs are to be positioned prior to their being fed endwise into a saw. Provided for carrying logs endo into this station, and ultimately into a saw, is a movable carriage 12. A log 14 is shown on the carriage in the station.
Provided on one side of the carriage is a laterally shiftable positioner including upright independently movable arms 16 which may be shifted toward and away from the carriage for the purpose of aligning a log thereon as desired. Shown schematically at 18 in Fig. l~ as being associated with the positioner arm seen in this figure, is a rack and pinion drive which i8 driven by an electric motor 20. ~ like drive and motor are provided for the other ar~. The motors are started and stopped through suitable conventional control apparatus, such as . ~
. , .
4.
, . . . . . .
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that represented in block form at 22.
What has been described so far is entirely conventional. --What is intended with this apparatus is that logs, such as log 14, are brought into station 10 on carriage 12 so that they may be engaged by arms 16 of the positioner. Prior to feeding such logs endwise into a saw, it is desired that each log ~e posi-tioned laterally on the carriage, whereby its side which is opposite arms 16, extends no further than a selected plane, such as that shown represented by line 24 in Fig. 1. When a log is so positioned, it is in proper lateral alignment for feeding into the mentioned saw.
Pro~ided according to the present invention for assist-ing in so positioning logs is a monitoring system including a pair of modulated laser sources 26, 27 and a pair of reflection detectors 28, 29 which are sensitive to the beams emitted by the sources. Source 26 and detector 28 are associated with the right-hand arm 16 in Fig. 2, and source 27 and detector 29 are ~, associated with the left-hand arm in this figure. The two sources are identical. Such also is true with respect to the detectors.
Source 26 includes a conventional laser 30 suitably coupled to a conventional amplitude modulator 32 which operates herein at a frequency of about 2000 Hz. The reason for using a modulator will be explained more fully shortly. Source 26 herein, when operating, projects along a line 33 (see Fig. 2) a modulated linear laser beam which occupies previously mentioned plane 24. Source 27 projects a similar beam along a line 35 (see Fig. 2? which also occupies plane 24.
Referring to Fig. 3 along with Figs. 1 and 2, detector 28, inside its housing, includes a lens 34, a relatively large-area photodet~ctor 36 which is coupled electrically through a modulating signal-pass filter 38 ~ith an output amplifier 40.
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~08~3Z~
All of these components in the detector are conventional.
Filter 38, in effect, "tunes" the detector for being sensitive only to reflected laser radiation which is modulated at the frequency of modulator 32. Thus, it will be seen that the reason for using and detecting a modulated laser beam is to increase the sensitivity of the overall system by making the system in effect, reject all other sources of optical radiation.
Provided between photodetector 36 and lens 34 are a field-of-view mask 42, and in front of this, a band-pass optical filter 44. Filter 44 is selected to pass, essentially, only light coming from laser 30. Provided in mask 42 is an elongated thin linear slot 42a, the purpose for which will be explained shortly.
As is clearly implied by its name, mask 42 defines the fieId of view of detector 28. With this mask being provided with slot 42a, the field of view of detector 28 is substantially planar. This field of view is indicated at 46 in Figs. 1 and 2, and it will be noted that the fieId has a wide expanse where it is adjacent station 10. Further describing the situation which exists, field of view 46 occupies a plane parallel to that of Fig. 1, and contains previously mentioned line 33. It will be noted that the upper reach of the field of view intersects line 33 at 46a and that the lower reach of the field intersects the line at 46b. Attention should especially be called to the fact that intersection point 46b is disposed above the top of carriage 12. Thus, the whole region, which is a linear region, wherein field 46 and line 33 intersect is spaced above the carriage. -This intersection region is referred to herein as a sensitivity region.
Detector 29 has a field of view 47 which is like field 46 except that it contains line 35. This field is show~ in Fig.
2. It will be noted that field 47 has an upper intersection 6.
. . , .. . . . - . . . . .
~0803'~4 with line 35 at 47a, and a lower intersection with this line at 47b. Point 47b is at substantially the same elevation above conveyor 12 as point 46b.
Referring again particularly to Fig. 3, a feature of the detector 28 which should be noted is that mask 42 may be laterally repositioned within the housing of the detector. The design of the specific means for allowing this is not important~. ' herein, and hence is not shown. It will be evident that reposi-tioning of the mask will relocate slot 42a, so as to shift the field of view of the detector. This feature is a desirable one in that it enables quick mounting of the detector in place, and ready fine ad~ustment of the location of the field of view so as.' to select precisely the region of intersection of this field and.
a laser beam like that which is projected from source 26. : ' The output of amplifier 40 in detector 28 is coupled ' to conventional control apparatus represented in block form at '~.
48. Control apparatus 48 is in turn connected to previously mentioned motor controller 22. The amplifier in detector 29 corresponding to amplifier 40 i8 similarly connected to control apparatus 48. The functioning of apparatus 48 will be explained shortly.
Explaining now how the system of the invention which has been described so far performs, sources 26, 27 and detectors 28, 29 are energized. As a conse.quence, the sources project , line-beams of modulated laser light along lines 33,.35 in plane ; 24. The detectors view these beams.in the planar fields of view shown at 46, 47, for the'purpose'of detecting any reflected l laser light. Light other than that produced by the lasers will .' be re~.ected by the'detectors,.both because of the presence of amplitude'~odulation which.'is.used with respect to the'beams, and because of the presence'of.band-pass optical filters in the ".
detectors. ' ~.
7.
. . ~ - , -108032~
A log is carried endwise into station 10 on conveyor 12 and is stopped so that it may be engaged by positioner arms 16. A suitable command is given to turn on the motors for the positioner arms, whereupon these arms advance toward the log across the conveyor.
It will typically be the casP that one end of a log '.
will be moved to where it intersects plane 24 before this happens with respect to the other end of the log. Assuming that what is shown as the right-hand end of log 14 in Fig. 2 is first to .' intersect plane 24, when this occurs, the part of the log which '~
: intersects the plane, it will be seen, lies within the field of view of detector 28, and also intersects the beam of light being ~-projected from source 26. As a consequence, light will be reflected to detector 28 which will then produce a control ' signal from amplifier 40 which, through the actions of control ' apparatus 48 and motor controller 22, shuts off motor 20.
The other positioner arm which is moving the left end of the log in Fig. 2 toward plane 24 will continue to operate until this end also intersects the plane. Like action will then take place with re~pect to the motor operating this other posi-tioner arm. More particularly, such intersection of plane 24 will result in light being reflected to detector 29 which, again through the combined actions of apparatus 48 and controller 22, will shut off the motor provided for.this other arm.
Log 14 is then properly positioned for advancement into a saw.
It will especially be noted th.at because of the way in which the'ields of.view o the'de.tectors are'arranged to inter-sect the'line-beams of light from.the'laser sources, any debris 3~ which ~a~ be'carried on.conveyor 12 will not produce any reflected '-:' light which mi:ght be.'det'ected by .t.he. de.tectors to.pro.duce false control signals. 'Also,:it will be no.ted that the'sensitivity .
. - - , , , .
~08~3;24 regions defined by the lengths of intersections of the fields of view and the laser beams are suitably spaced from the conveyor, whereby movement of the conveyor parts will not effect any false control signals.
Let us consider now the embodiment of the invention illustrated in Figs. 4 and 5. Shown herein generally at 50 is a station for scaling logs, through which station logs, such as log 52, are transported by an elongated conveyor 54. Suitably disposed above conveyor 54, in a housing 56, is a laser source 58 including a laser 60 which is like previously described laser 30, and an amplitude modulator 62 which is like previously described modulator 3Z. Also included in source 58, within housing 56, are a parabolic mirror 64, a rotary-mounted mirror 66, and a motor 68 which is drivingly connected to mirror 66 to ' rotate'the same.' Mirror 66 is rotatable about a horizontal axis ~'' shown at 70--this a~is lying in the'same horizontal plane con-taining laser 60 and modulator 62.
The reIative positions of the laser, modulator and rotating mirror in Figs. 4 and 5 are shown only schematically in these figures. The laser and modulator are positioned so as to project a modulated laser beam toward the inclined surface 66a of mirror 66, with this beam lying in the same horizontal plane containing axis 70. With rotation of the mirror, in the direc-tion of arrow 72 seen in Fig. 4, the rotating mirror scans the beam of the laser along and across the'parabolic surface of mirror 6h. The direction of traveL of the scanned beam across the'mirror i8 indicated by arrow 74 in Fig. 4.
With operation of source'58, there~ore, what is produced i8 a subatantially vertical, planar, swept beam of laser light ~ 30 which'occupies the'vertical plane'sho'wn at 76 in Fig. 5, and '~ which'has thé'width indicated as ~ in Fig. 4. 'It will be seen that thi's planar beam is directed t~ard conveyor 54, and extends ~... . . . . . .
- ,. ;
.. . . . .. .. . . . .
~3133~
a considerable distance on opposite sides of the conveyor.
Also included in the monitoring system used in conjunc- -tion with scaling station 50 are two detectors 78, 80 which are ~-each extremeIy similar in construction to previously described detector 28, except that the fieIds of view of detectors 78, 80 are pyramidal rather than planar. The configuring of such fieIds of view for these detectors may readily be accomplished by providing them with masks, such as mask 42_, in which a generally rectangular aperature is provided for defining such fieIds of view. The'fields of view of detectors 78, 80 are --shown at 82, 84, respectiveIy.
As can be seen in Fig. 4, detectors 78, 80 are located above and on opposite sides of conveyor 54, and look downwardly at angles toward the conveyor. As can be seen in Fig. 5, the detectors are located longitudinally to one side of source 58 whereby they look downwardly at an angle toward conveyor 54 in the region of plane 76.
It will thus be apparent that the fields of view of the detectors, where these fields intersect plane 76 (which is the'plane of the scanned laser beam) produce regions of intersec-tion which have both length and breadth dimensions in plane 76. ':
Such a region of intersection, called a sensitivity region, is shown generally at 86 in Fig. 5. An important consideration herein is that the'detectors are'also oriented whereby no por- '' tions of their fields of view in the region of intersection with plane 76, touch conveyor 54. 'Further, these regions of intersec- ' tion are located above'the'top surface of the conveyor.
In the'system shown in Figs. 4 and 5, it is intended '~
that output signals from the'det'ectors be'used to compute log diameter along the'length'of a log such as log 52. 'The'exact way in which'such computations are'performed is no part of the present invention. 'However, reference'may be made'herein to 10. :`
., :
,. ..
1~ 80 32 ~
u.s. Patent No. 3,997,269 to Clifford ~. Moulton for "Scaling Apparatus With Linearization compensation". This patent discloses apparatus usable in the present sYStem to reIate the output signals produced by detectors 78, 80 to the -angular position of mirror 66 with respect to mirror 64, whereby log diameter dimensions may accurately be determined.
Regardless of how the output signals produced by detectors 78, 80 are specifically used, the system shown in Figs. 4 and 5 performs with mirror 66 scanning a beam of laser light in plane 76, which beam is viewed in the fields of view of detectors 78, 80 to look for any reflections. Just as was the ' case with the'system shown in Figs. 1 and 2, wood chips or other debris carried on conveyor 54 will produce no false output signals. Further, movement of the conveyor parts will not produce such a signal. The only event which will result in a ~' signal, whi'ch will be a proper signal, is the presence in a region of intersection of a field of view 'of one'of the detectors and plane 76 of an object which'reflects the scanned laser beam.
The arrangement of the detectors, as has been explained, is such that this event will only occur when an article of interest, such as log 52, intersects one of these regions.
It will thus be apparent that a very simple and effec-tive system is proposed by the in~ention for monitoring the presence o~ an article at a selected location. The system can be used also for measuring dimensions. By utilizing beams of optical radiation, such as those'described, which beams are '~
'~ intersected by the angularly disposed, defined wide-'expanse fields of view of optical detectors, sensitivity regions are ~ `
defined which may be geometrically spaced so as to avoid false~
signal problems which have'characterized previously available scanning or monitoring equipment. 'It will also be'apparent that JP~;' 11. :
~., . .. . ~ , , - .-~08~3Z~
a system embodying the invention may take a number of different forms and may readily be incorporated in various different kinds of apparatus. Further, by equipping a detector in the system with a shiftable mask, such as that described herein, placing of a system becomes an extremely simple operation, since fine adjustments for positioning the desired region of sensitivity may be made simply by shifting the position of the mask in the detector. It will be recognized, of course, that fields of view may be specially configured to suit different applications. :
While two embodiments of the invention have been described herein, it is appreciated that other variations and modifications may be made without departing from the spirit of the inventlon.
. .
. . .
, ':
~ 30 ~, ..
: ., 12.
Claims (12)
1. An electro-optical monitoring system for noting in an observation zone the presence of a solid and essentially non-transparent article, particularly a log to be fed into a saw, comprising at least one means for projecting into said zone a beam of optical radiation, and at least one detector means sensitive to said radiation, wherein said at least one projecting means is adapted to generate a beam which, when viewed from at least one side, has substantially the appearance of a straight line, said at least one detector means is a reflection detector means constructed to have a defined field of view broadening in the direction away from the detector means and intersecting said beam along a finite length thereof, said intersection producing a sensitivity region of pre-selected extension and location in said zone, and said at least one projecting means and at least one detector means being oriented relative to one another so that the latter is unable to view directly radiation projected by the former and only can perceive radiation emitted from the former after reflection on a solid article positioned within said sensitivity region.
2. The system of claim 1, wherein said beam, when viewed from any side, appears as a substantially straight line, and the field of view of said detector means lies in a plane containing said beam so that an essentially line-shape sensitivity region is obtained.
3. The system according to claim 1, which further includes means adjacent said zone for supporting an article in the zone, and wherein said beam projects toward said support means, and said sensitivity region is spaced from said support means.
4. The system according to claim 1 wherein said means for projecting a beam comprises a laser.
5. The system of claim 1 wherein said beam is essentially planar, and the field of view of said detector means, where it intersects said beam, has as well length as breadth dimensions in the plane of said beam.
6. The system of claim 5 wherein the field of view of said detector means is pyramid shaped.
7. The system according to claim 5 or 6 wherein means for turning the beam in a pre-selected plane are provided.
8. The system according to claim 5 or 6 wherein the said at least one means for projecting comprises a modulator for coding the said beam and the said at least one detector means comprises a corresponding modulating signal pass filter.
9. The system according to claim 5 or 6 wherein the said at least one detector means comprises a band-pass optical filter which allows to pass only radiation from the said at least one means of projection.
10. The system according to claim 1, wherein the said at least one detector means comprises a field-of-view diaphragm in the form of a mask in which an opening defining the shape of the field-of-view is arranged.
11. The system of claim 10 wherein the said mask is for a fine setting of the field-of-view, arranged movably in the said at least one detector means.
12. System according to claim 1, 2 or 11 wherein the output signal of the said at least one detector means through electronic manoeuvre means controls a device for mechanical change of position of the monitored solid article.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US63406675A | 1975-11-21 | 1975-11-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1080324A true CA1080324A (en) | 1980-06-24 |
Family
ID=24542300
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA266,077A Expired CA1080324A (en) | 1975-11-21 | 1976-11-19 | Electro-optical monitoring system |
Country Status (6)
| Country | Link |
|---|---|
| AU (1) | AU508268B2 (en) |
| CA (1) | CA1080324A (en) |
| DE (1) | DE2648181A1 (en) |
| FI (1) | FI73522C (en) |
| NO (1) | NO144026C (en) |
| SE (1) | SE406825B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015038109A1 (en) * | 2013-09-11 | 2015-03-19 | Halliburton Energy Services, Inc. | Method and apparatus for aligning components of integrated optical sensors |
-
1976
- 1976-10-19 SE SE7611567A patent/SE406825B/en not_active IP Right Cessation
- 1976-10-25 DE DE19762648181 patent/DE2648181A1/en not_active Ceased
- 1976-11-18 FI FI763296A patent/FI73522C/en not_active IP Right Cessation
- 1976-11-18 NO NO763930A patent/NO144026C/en unknown
- 1976-11-19 CA CA266,077A patent/CA1080324A/en not_active Expired
- 1976-11-22 AU AU19856/76A patent/AU508268B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| NO144026C (en) | 1981-06-03 |
| FI73522B (en) | 1987-06-30 |
| DE2648181A1 (en) | 1977-06-08 |
| FI763296A (en) | 1977-05-22 |
| SE7611567L (en) | 1977-05-22 |
| NO763930L (en) | 1977-05-24 |
| NO144026B (en) | 1981-02-23 |
| AU1985676A (en) | 1978-06-01 |
| FI73522C (en) | 1987-10-09 |
| SE406825B (en) | 1979-02-26 |
| AU508268B2 (en) | 1980-03-13 |
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