SE449136B

SE449136B - Sweeping beam measurement process using radiation

Info

Publication number: SE449136B
Application number: SE8105050A
Authority: SE
Inventors: S Eliasson; G Mork; P Strandberg
Original assignee: Kockums Ind Ab
Priority date: 1981-08-26
Filing date: 1981-08-26
Publication date: 1987-04-06
Also published as: SE8105050L

Abstract

The process is for measuring an object with two side surfaces which is illuminated by at least one radiation source. The radiations reflected on the object are picked up by two detectors fitted over it. The detectors produce electrical signals proportional to the picked-up radiations, which are fed to an electronic evaluation unit. The measurement object (10), through individual sweeps, (A) is investigated along a stretch comprising a sweep area, using a bunch of radiations moving at an adjusted speed. Each of the detectors (22') with their vision fields (22A) cover each side surface (10b,10c) and the whole of the upper surface (10a) of the object, and produce a signal sequence. The evaluation unit provides as an indication of the measurement sweep one end point and the signal sequence's first passage from values below a set threshold value to those above it. (Provisional Basic advised week K15)

Description

449 136 \ tur, i och för överföring av styrsignaler, ansluten till ett kant- verk 16 i vilket icke visade, i och för sig kända riktorgan_är mon- terade som i beroende av mottagna styrsignaler inställer det re- lativa läget av en via en andra transportör 12 inmatad bräda i förhållande till kantverkets bearbetningsorgan. Ur kantverket 16 utmatas sedan på en tredje transportör 13 en kantad bräda 10'. 449 136 \ in turn, for the transmission of control signals, connected to an edge plant 16 in which the guide means not shown, known per se, are which, depending on the control signals received, sets the the relative position of a board fed via a second conveyor 12 into relation to the edging plant's processing means. From the edging 16 then an edged board 10 'is discharged on a third conveyor 13.

För framtagning av lämliga styrsignaler i elektronikskåpet 15 måste konturerna av den okantade brädan 10 uppmätas och i form av mätsignaler via elektriska ledningen 20a inmatas i elektronik- skåpet.For the production of suitable control signals in the electronics cabinet 15 the contours of the unedged board 10 must be measured and shaped of measurement signals via the electrical line 20a are input to the the cabinet.

Enligt fig. 2 innefattar sändarenheten 21 sgm en parallellrik- tare en stationär konkav spegel 213 i form av en till parabelform böjd plan remsa, en roterande motordriven planspegel 212 i para- belspegelns 213 brännpunkt, och en strålningskälla, exempelvis en laserdiod 211 som riktar sin stråle resp. sitt strålknippe §_på den plana spegeln 212. Genonxplanspegelns rotation enligt P3 fås att det från parabelspegeln reflekterade strålknippet S{T_S2 ... förskjuts parallellt med sig själv, dvs att en "parallell svep- stråle" erhålles. Varje svep har en längd Ä.According to Fig. 2, the transmitter unit 21 sgm comprises a parallel direction a stationary concave mirror 213 in the form of another parabolic shape curved flat strip, a rotating motor-driven flat mirror 212 in the focal point of the bell mirror 213, and a source of radiation, for example a laser diode 211 which directs its beam resp. its beam §_on the plane mirror 212. The rotation of the genonxplan mirror according to P3 is obtained that the beam S {T_S2 ... reflected from the parabolic mirror ... displaced in parallel with itself, i.e. a "parallel sweep" beam "is obtained. Each sweep has a length Ä.

Brädan 10, som bildar mätföremâlet, har en smalare plan övre yta 10a, tvâ sneda sidoytor (vankanter) 10b, 10c och en bredare plan undersida 10d. Dessa ytor möts utmed längsgående kanter vilka i tvärsnittet framträder som hörnpunkter Cl: t2: t3f t4 0Ch i Sí9na1“ diagrammen (fig. 3a, Jb; som hörnen tl', tz", t3', t4“.The board 10, which forms the measuring object, has a narrower flat upper surface 10a, two oblique side surfaces (van edges) 10b, 10c and a wider plane underside 10d. These surfaces meet along longitudinal edges which in the cross section appears as vertices Cl: t2: t3f t4 0Ch in Sí9na1 “ the diagrams (fig. 3a, Jb; as the corners tl ', tz ", t3', t4".

Svepstrålen S1, S2 ... utstakar på mätföremålets 10 övre yta 10a och på de båda sidoytorna 10b, 10c en svep- eller avsökningszon Q; Utmed hela denna zon Q reflekteras den mottagna strålningen prak- tiskttagetåt alla håll, dvs också mot sidorna där detektorerna 22' och 22” är anordnade. Dessa detektorer har var sitt synfält 22'A och 22"A och är härvid så riktade, att de med sina respekti- ve synfält från var sin sida omfattar mätföremâlet 10,dock så, att vid sidan av den övre ytan endast mätföremålets främre, men in* te den bortvända bortre sidoytan ligger i en detektors synfält.The sweep beam S1, S2 ... protrudes on the upper surface 10a of the measuring object 10 and on the two side surfaces 10b, 10c a sweep or scan zone Q; Along this entire zone Q, the received radiation is practically reflected taken in all directions, ie also towards the sides where the detectors 22 'and 22' are arranged. These detectors each have their own field of view 22'A and 22 "A and are so oriented that they, with their respective field of view from each side comprises the measuring object 10, however, that next to the upper surface only the front of the measuring object, but in * te the facing far side surface is in a detector's field of view.

Anordningen arbetar på följande sätt. I den mån som svepstrålen S1, S2 ... sveper utmed zonen Q, mottar båda detektorerna ref- lekterad strålning med varierande intensitet och alstrar en följd 449 15 av elektriska mätsignaler med varierande intensitet.I fig 3 visas för- loppet av signalföljden hos detektorn 22' och i fig. 3b hos detek- torn 22" (fig. 1). På abskissaxeln anges tiden, och på ordinat- axeln signalintensiteten,alternativt sträckan (vid given svep- hastighet). Linjen Q_anger ett förbestämt tröskelvärde överen noll-linje Q. Med t1', t2" etc. betecknas i båda diagrammen de Ställen Vilka mßtsvarar svepstrâlknippets passage förbi mätföremâlets hörn t1, tz, etc. i fig. 2. Fastän vankanterna 10b och 10c på grund av sitt lutande läge, och i allmänhetmörkare färg, har mindre reflektionsförmåga än den övre plana ytan 10a, Så kan ändå en till detektorn tillvänd vankant på grund av sitt läge avge en kraftigare signal än den plana ytan. ' ü Vid känd och i utvärderingsenheten 15A ingiven svephastighet kan de verkliga avstânden mellan punkterna t1, t2 etc. på mätföre- målet lätt fastställas. I fig. 3a och šbmligger över linjen Q zonen motsvarande mottagningen av reflekterad strålning.The device operates in the following manner. To the extent that the sweep beam S1, S2 ... sweeps along the zone Q, both detectors receive ref- reflected radiation of varying intensity and produces a sequence 449 15 of electrical measuring signals of varying intensity. Fig. 3 shows the the course of the signal sequence of the detector 22 'and in Fig. 3b of the detector tower 22 "(Fig. 1). On the abscissa axis the time is indicated, and on the ordinate the axis signal intensity, or the distance (at a given sweep speed). The line Q_anges a predetermined threshold value above zero line Q. With t1 ', t2 "etc., both diagrams denote de Places which correspond to the passage of the sweep beam past the measuring object corner t1, tz, etc. in Fig. 2. Although the vanes 10b and 10c due to its sloping position, and in general darker color, has less reflectivity than the upper planar surface 10a, So can still a vankant used to the detector due to its position emit one stronger signal than the flat surface. 'ü At known and in the evaluation unit 15A the sweeping speed entered can the actual distances between points t1, t2, etc. on the measuring the goal is easily set. In Fig. 3a and šbm lies over the line Q zone corresponding to the reception of reflected radiation.

Ur betraktande av fig. 2 och 3a, 3b framgår att genom samverkan av de båda detektorerna 22' och 22" lägen för alla fyra relevan- ta "hörn" t1 - t4 kan fastställas med ledning av ställena tl', t2", W” t3' och tgïi signaldiagrammen.From consideration of Figs. 2 and 3a, 3b it appears that by cooperation of the two detectors 22 'and 22 "positions for all four relevant take "corner" t1 - t4 can be determined by the positions tl ', t2 ", W" t3 'and tgïi the signal diagrams.

I fig. 2 visas vidare att brädan 10 har en defekt i form av ett kvisthal 101 med dimensionen y. Där reflekteras givetvis prak- tiskt taget ingen strålning alls, vilket i signaldiagrammen fram- träder som gap mellan punkterna ts' och t6' resp. ts" och tö".Fig. 2 further shows that the board 10 has a defect in the form of a twig hall 101 with the dimension y. This of course reflects the virtually no radiation at all, as shown in the signal diagrams appears as a gap between the points ts 'and t6' resp. ts "and thaw".

För att inte t.ex. endast sträckan tz' - t5' ellerntš" - tšï_ skall kunna uppfattas som bredden av hela brädan 10, är utvärde- ringsenheten 15A programmerad att som mätsträckans pegynnelsepunkt registrera signalföljdens första övergång från zonen motsvarande icke-mottagning av på mätföremålet reflekterad strålning (zonen under linjen D i fig. 3a och 3b) till zonen för mottagning av reflekterad strålning (över linjen Q), och som mätsträckans slutpunkt den sista övergången av signalföljden från zonen för mottagning av reflekteras strålning (över linjen Q) till zonen för icke-mottagning (under linjen Q). Därigenom uppnås "undertryckning" av kvisthâl och andra defekter som orsakar utsläckning av reflexen från den sågade plana ytan. Märke bör läggas till att utvärderingseneheten mottager signalföljderna från båda detektorerna och att nämnda första och sista övergångar i regel inte förekommer i en och samma detektor. 449 1_36 Registrering avhörnpunkterna§¿L, §¿1, t¿l, t¿: sker i ut- värderingsenheten på följande sätt.In order not to e.g. only the distance tz '- t5' orntš "- tšï_ should be perceived as the width of the whole board 10, is evaluated the ring unit 15A is programmed to be the starting point of the measuring distance register the first transition of the signal sequence from the corresponding zone non-reception of radiation reflected on the measuring object (zone below line D in Figs. 3a and 3b) to the zone for receiving reflected radiation (across the line Q), and as the end point of the measuring distance the last the transition of the signal sequence from the zone for receiving is reflected radiation (above the line Q) to the non-reception zone (below the line Q). This achieves "suppression" of twig holes and other defects which causes the reflex to be extinguished from the sawn flat surface. Make should be added that the evaluation unit receives the signal sequences from both detectors and that said first and last transitions as a rule does not occur in one and the same detector. 449 1_36 Registration of the corner points§¿L, §¿1, t¿l, t¿: takes place in ut- the valuation unit as follows.

Breddkoordinater genereras genom att med början ñﬁm en tid motsvarande svepets början, vid varje utsänd laserpuls görs en uppräkning av innehållet i ett av utvärderingsenhetens register. Koordinaten kopieras därefter omedelbart till något av fyra andra register där man efter svepets slut kan erhålla hörn- punkterna. Detta sker genom att regisuæmnas adresser bestäms del- vis av datorprogrammet, delvis av de logiska nivåerna hos tvâ bi- stabila vippor vilka av respektive detektorsignal kan ställas i läge “1" och av en nollställningsimpuls i läge "O".Latitude coordinates are generated by starting with ñ ﬁ m a time corresponding to the beginning of the sweep, at each transmitted laser pulse a list is made of the contents of one of the evaluation unit register. The coordinates are then immediately copied to one of four other registers where, after the end of the sweep, one can obtain the points. This is done by determining the addresses of the directors of the computer program, in part by the logical levels of two stable flip-flops which can be set by the respective detector signal position "1" and of a reset pulse in position "0".

Vid svepets start uppvisar båda vipporna läget "00".”ïnnan anordningens detektorer har uppfångat någon reflex, kommer därför koordinatvärdet varje gång att inl sas i motsvarande register. Lä- get av t¿l erhålls därför genom att ett inkrement läggs till talet i detta register. Pâ samma sätt erhålls t¿: från registret med ad- ressen innehållande "O1".At the start of the sweep, both flip-flops have the "00" position the detectors of the device have detected any reflex, therefore the coordinate value each time to be entered in the corresponding register. Leeward- the number of numbers is therefore obtained by adding an increment to the number in this register. In the same way, t¿ is obtained from the register with ad- the race containing "O1".

När t¿ï har passerats, ändras registreringen så att den av datorprogrammet bestämda adressdelen ändras och vipporna áterställs till "OO" efter varje registrering. Härigenom uppnås att vid den nya adressen “11" lagras t¿l, medan t¿: erhålls vid "10".Once t¿ï has been passed, the registration is changed so that it is off the computer part determined address part is changed and the flip-flops are reset to "OO" after each registration. This achieves that at it the new address "11" is stored tæl, while t¿: is obtained at "10".

I fig. 4 visas ett alternativt utförande av mätanordningen enligt uppfinningen, utan konkavspegeln 213 och där svepstrålen inte för- flyttas utmed inbördes parallella, utan divergenta banor såsom S"1, S"2. Nackdelen med denna - konstruktionsmässigt enklare - -fïföringsform är, att avståndet mellan den roterande planspegeln 212 och mätföremålet 10 är kritiskt, vilket annars inte alls är fallet med den "parallella svepstrålen" enligt fig. 2. Konstruk- tionen enligt fig. 2 är således bl.a. okänslig för mätföremâlets Olika tjOCklekSVärden E . I övrigt bör anmärkas att även dessa dessa tjockleksvärden kan avkännas på konventionellt sätt, exem- pelvis via tryckrullar 18 vilka uppifrån sänks ned på mätföremålet, och motsvarande mätsiqnaler inmatas i utvärderings- enheten 15A. Där kan således det optimala utbytet ur en given bräda beräknas inte endast yt-, utan även volymmässigt.Fig. 4 shows an alternative embodiment of the measuring device according to invention, but the concave mirror 213 and where the sweep beam is not moved along mutually parallel, without divergent paths such as S "1, S" 2. The disadvantage of this - simpler in terms of construction - The embodiment is that the distance between the rotating plane mirror 212 and the measuring object 10 is critical, which otherwise is not at all the case of the "parallel sweep beam" of Fig. 2. the tion according to Fig. 2 is thus i.a. insensitive to the measurement object DIFFERENT THICKNESS VALUES E. In other respects, it should be noted that these too these thickness values can be sensed in a conventional manner, e.g. pelvis via pressure rollers 18 which are lowered onto from above the measuring object, and the corresponding measuring signals are entered in the evaluation unit 15A. There can thus be the optimal yield from a given board is calculated not only in terms of surface area, but also in terms of volume.

Känsligheten för mätobjektets tjocklek kan hos anordningen enligt fig.4 undanröjas genom att använda ett på något annatkäﬂt Sätt än via 449 13 detektorerna uppmätt tjockleksvärde. Dock kan i anordningen enligt fig. 4 alltför branta vankanter inte upptäckas, om inte mätavståndet (10 - 212) görs rätt långt (i storleksordningen l0m).The sensitivity to the thickness of the measuring object can be in the device according to fig.4 eliminated by using one on any other way than via 449 13 the detectors measured thickness value. However, in the device according to Fig. 4 excessive steep edges are not detected, unless the measuring distance (10 - 212) is made quite long (in the order of l0m).

Fastän det för enkelhets skull ibland talas om en svepstråle, gäl- ler det givetvis alltid ett strâlknippe, eftersom en enda strâle inte har någon breddimension. Spâret §l (fig. 5) av svepstrâlknip- pet på mätföremålet har en given breddimension k, vars värde be- stäms av praktiska överväganden, och en vald längddimension l i mätföremålets frammatningsriktning P1. Längddimensionen k väljs med fördel sådan, att vid given svephastighet i pilens P3' rikt- ning, och vid given frammatningshastighet i pilens Pl riktning, de enstaka svepzonerna C1, C2, C3 ... åtminstone berör, och helst något överlappar varandra i nämnda riktning Pl. Därigenom avsöks mätföremàl utan avbrott, dvs kontinuerlig täckning av hela mät- föremålet uppnås.Although for simplicity it is sometimes referred to as a sweep beam, of course, there is always a beam, because a single beam has no width dimension. The groove §1 (Fig. 5) of the sweep beam on the measuring object has a given width dimension k, the value of which is is determined by practical considerations, and a selected length dimension l i measuring direction P1 of the measuring object. The length dimension k is selected advantageously such that at a given sweep speed in the direction of the arrow P3 ' and at a given feed rate in the direction of the arrow P1, the individual sweep zones C1, C2, C3 ... at least touch, and preferably slightly overlapping each other in said direction P1. Thereby scanning measuring objects without interruption, ie continuous coverage of the entire measuring the object is achieved.

Ett prövat utföringsexempel uppvisar följande parametrar: Frammatningshastighet i riktningen Pl: 2,2 m/sec Sveplängd (A) __ 512 mm Svepfrekvens 200 svep/minut Svepstrålknippets tvärsnittsdimensioner l = llmm, k = 2mm LjuSkälïa= diodlaser LBl från bolaget ITT Detektorernas synfält: 21° Första transportören: längd 6,5 m Andra transportören: längd 8 m Upplösning i längdled: 11 mm Mätupplösning: 1 mm En avkortning av anordningens hela bygglängd uppnås när i stället för en enda mätanordning enligt uppfinningen flera sådana, exem- pelvis 3 st i inbördes avstånd på omkring 2_m används. Då är mätningen klar innan mätföremålet pâ exempelvis 6 m har framma- tats utmed en sträcka svarande mot hela dess längd, och t.ex. den andra transportören 12 kan avkortas till omkring 3 m.A tried and tested exemplary embodiment has the following parameters: Feed rate in the direction P1: 2.2 m / sec Sweep length (A) __ 512 mm Sweep rate 200 sweeps / minute The cross-sectional dimensions of the sweep beam l = llmm, k = 2mm LjuSkälïa = diode laser LBl from the company ITT Field of view of the detectors: 21 ° First conveyor: length 6.5 m Second conveyor: length 8 m Longitudinal resolution: 11 mm Measuring resolution: 1 mm A shortening of the entire construction length of the device is achieved when instead for a single measuring device according to the invention several such, e.g. pelvis 3 pcs at a mutual distance of about 2_m are used. Then is the measurement is completed before the measuring object of, for example, 6 m has taken along a distance corresponding to its entire length, and e.g. the the second conveyor 12 can be shortened to about 3 m.

Toppkapaciteten av en anordning enligt uppfinningen inom sågverks- industrin ligger vid omkring 20 brädor per minut vid en medel-The peak capacity of a device according to the invention in the sawmill the industry is at about 20 boards per minute at an average

Claims

449 136 length of 4.5 m and a feed speed of 132 m / min. if the feed speed is increased to 200 m / min_, the peak capacity rises to 25 boards / min., and the length of the other conveyor must be increased to 10 m, if a measuring device is used, resp. to 4 m, when three measuring devices are used. As a light source, a pulsed diode laser, but also any other light source, for example a gas laser, can be used. The advantage of a pulsed diode laser is greater output power, longer service life in operation, and unlimited service life in storage, as well as lower price and suppression of interference (thanks to optimal adaptation light source detector and pulsation that concentrates the light flux, however, the gas laser must and per se known method is modulated with some external device to avoid interference from the ambient lighting). As a detector 22 ', 22 "(Fig. 1) a photodiode 22c (Fig. 2) is advantageously used which is imaged by a collection lens 22a towards the part of the measuring object 10 which is scanned. is obtained only for light pulses of a length emitted by the light source in a measuring device (in the order of one-tenth of a microsecond) .In contrast to other measuring methods (eg with diode-ET 'array cameras), a practically complete suppression of static or slow varying light sources in the environment (such as daylight or electric lighting) It should be noted that the focus of the detectors does not affect the measured values and that no aperture and / or distance setting is required.

A method for measuring the width of a board (10) having two side surfaces (10b, 10c) of which at least one is an oblique vane, and having two planar sawn surfaces (10a, 10d) one of which is narrower than the other and together with the two side surfaces are illuminated by a radiation source (211) and brought into field of view (22'A, 22 "A) by two radiation detectors (22 ', 22") which generate measurement signals varying in intensity in function of intensity variation. radiation received on the board when the board is scanned by scanning in a scanning zone (C) in the measuring direction 444 156, said measuring signals from both detectors being input into a computerized programmable electronic device (1SA) type computer or minicomputer, where they are combined for evaluation and calculation of the desired width dimension, characterized in that the electronics unit is programmed to register as the starting point of the measuring distance the first time during a given sweep when the signal intensity increases over a selection t threshold value (D), to register as the end point of the measuring distance the last time during the same sweep when the signal intensity falls below said threshold value, and to determine all the intermediate transitions of the signal intensity (t'5 - t'5, t ") for determining the dimension of the measuring distance 5 - t "5) of the threshold value in either direction, so that measurement errors caused by the presence of defective places (101) on the narrower flat surface which have reduced reflectivity are eliminated.

Method according to claim 1, characterized in that said sweep is effected by displacing a beam (S1) parallel to itself in the measuring direction, the detectors being arranged stationary.

3. A method according to claim 1, characterized in that said sweep is effected by swinging a beam (Sl “) in the measuring direction along divergent paths around a center point, the detectors being arranged stationary.

4. A method according to any one or more of the preceding claims when used in a board fed in its longitudinal direction during the measurement, characterized in that the board is scanned without interruption by its feed rate - the speed of the sweep and the extent of the scanning zone ( l) in the individual sweep zones (Cl-Cs) On the board follow one after the other without spaces.

Method according to claim 4, characterized in that the feed speed is in the order of 2.2 m / sec, the sweep length (A) 512 mm, the sweep frequency 200 / min and the said extent of the scanning zone is 11 mm.

A method according to any one or more of the preceding claims, characterized in that said defective sites are registered.

Method according to one or more of the preceding claims, characterized in that said threshold value is selected below the signal intensity (t'1, t "r) which corresponds to the connection point of the van edge (10b, 10c) (t1). , tt) to the wider planar sawn surface (10dL so that positions for all four corners (tl - tt) in a cross section of a board can be determined.

A method according to any one or more of the preceding claims, characterized in that said illumination is provided by pulsating laser radiation.

Method according to Claim 8, characterized in that in the electronic unit for producing the measurement result, positions are determined for four corner points (t1, tg, ta, tr) of a cross section of a board, by generating width coordinates by at the beginning of each laser pulse, the contents of a register in the electronic unit are counted and the coordinates are immediately copied to one of four other registers present in said unit whose addresses are determined partly by the program and partly by logic levels of two bistable flip-flops which can be measured from each detector. set to position "1" and by a reset pulse to position "0". and which at the beginning of the scan is the position "0", wherein before the detectors have captured any reflected radiation, the coordinate value is read in each time in the corresponding register, while the position (t'1) of the first corner point (t1) is obtained by laying an increment to the number in this register, the position (t "2) for the other corner point (t2) is obtained in the same way from the register with the address containing" 01 ", after which the registration is changed so that the address part determined by the program is changed and the flip-flops are reset to "OO" after each registration, so that at the new address "11" the position (t'g) of the third corner point (tg) is stored while the position (t "~) of the fourth (tu) is obtained at the address "10".

Method according to one or more of the preceding patent claims, characterized in that the thickness (m) of the board is also sensed and the corresponding value is entered in the electronic unit for volume exchange optimization. m-v - -. ~ .qwr-4 ..... ~ ._ .. ~ -..---