United States Patent (19)
`Watkins et al.
`
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`US005275327A
`5,275,327
`(11) Patent Number:
`Jan. 4, 1994
`(45) Date of Patent:
`
`(54 INTEGRATED OPTICAL SENSOR
`Arthur D. Watkins; Herschel B.
`75) Inventors:
`Smartt; Paul L. Taylor, all of Idaho
`Falls, Id.
`73) Assignee: EG&G Idaho, Inc., Idaho Falls, Id.
`(21) Appl. No.: 960,329
`22 Filed:
`Oct. 13, 1992
`51) Int. Ci.......................... B23K9/12; G06F 15/46
`52) U.S. C. ........................................ 228/102; 228/9;
`219/124.34; 219/130.01
`58) Field of Search ........................ 228/102, 105, 7-9;
`29/407,702, 709; 219/124.34, 130.01; 250/559
`References Cited
`U.S. PATENT DOCUMENTS
`4,306,144 12/1981 Masaki .................
`... 219/24.34
`4,649,426 3/1987 Bolstad .....
`... 358/O1
`4,654,949 4/1987 Pryor .................................... 29/407
`4,877,940 10/1989 Bangs et al. .
`... 219/124.34
`4,951,28 8/1990 Okumura ........................ 219/124.34
`5,150,175 9/1992 Whitman ............................. 250/559
`OTHER PUBLICATIONS
`Agapakis, et al., Joint Tracking & Adaptive Robotic
`Welding Using Vision Sensing of the Weld Joint Geom
`etry, Welding Journal, vol. 65, No. 11, pp. 33-41 (1986).
`Hanright, Robotic Arc Welding Under Adaptive Con
`
`(56)
`
`trol-A Survey of Current Technology, Welding Jour
`nal, vol. 65, No. 11, pp. 19-24 (1986).
`Richardson, et al., Coaxial Arc Weld Pool Viewing for
`Process Monitoring & Control, Welding Journal, vol.
`63, No. 3, pp. 43-50 (1984).
`Lukens, et al, Infrared Temperature Sensing of Cooling
`Rates for Arc Welding Control, Welding Journal, vol.
`61 No. 1, pp. 27-33 (1982).
`Primary Examiner-Samuel M. Heinrich
`Attorney, Agent, or Firm-Alan D. Kirsch
`(57)
`ABSTRACT
`An integrated optical sensor for arc welding having
`multifunction feedback control. The sensor, comprising
`generally a CCD camera and diode laser, is positioned
`behind the arc torch for measuring weld pool position
`and width, standoff distance, and post-weld centerline
`cooling rate. Computer process information from this
`sensor is passed to a controlling computer for use in
`feedback control loops to aid in the control of the weld
`ing process. Weld pool position and width are used in a
`feedback loop, by the weld controller, to track the weld
`pool relative to the weld joint. Sensor standoff distance
`is used in a feedback loop to control the contact tip to
`base metal distance during the welding process. Cooling
`rate information is used to determine the final metallur
`gical state of the weld bead and heat affected zone,
`thereby controlling post-weld mechanical properties.
`
`21 Claims, 6 Drawing Sheets
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`Laser and shutter
`powericontrol
`Renote head
`camera interface
`
`Camera power
`& video signal
`
`External Camera
`Controller
`
`
`
`1
`
`Field of view
`... . . Laser beam
`
`
`
`
`
`Laser Power Supply
`& Shutter Control
`28
`
`Video signal
`
`
`
`Camera gain
`control
`
`Shutte?
`control
`signal
`
`Analog/Digital Signal
`Conditioning
`30
`
`Weiding direction
`
`
`
`
`
`
`
`Computer
`24
`
`
`
`Serial Line
`
`Google Ex. 1028, p. 1
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`

`

`U.S. Patent
`
`Jan. 4, 1994
`
`Sheet 1 of 6
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`5,275,327
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`
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`
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`
`
`
`
`
`
`
`Laser and shutter
`power/control
`Remote head
`Camera interface
`
`Camera power
`& video signal
`
`External Camera
`Controller
`
`
`
`/ --- Field of view
`. . . . . Laser bean
`
`Welding direction
`auma-amaumaruammammare
`
`
`
`
`
`
`
`
`
`
`
`Computer
`24
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`
`
`Serial Line
`
`
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`
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`
`
`Laser Power Supply
`& Shutter Control
`28
`
`Video signal
`
`Camera gain
`Control
`
`Shutter
`Control
`signal
`
`Analog/Digital Signal
`Conditioning
`30
`
`Fig.
`
`Google Ex. 1028, p. 2
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`

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`U.S. Patent
`
`Jan. 4, 1994
`
`Sheet 2 of 6
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`5,275,327
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`r - a - - a - - - - -
`
`-- -
`
`- - --- -
`
`Environmental Rack
`
`-
`
`m - ru - -- - - - - - -- - - -
`
`-
`
`- -
`
`Sensor
`-----------------------
`
`0.
`Diode Laser Electronics
`
`CW Diode Laser
`
`Diode Laser
`Shutter
`
`CCD Camera
`Head and Optics
`
`Debug
`
`Monitor
`
`Keyboard
`
`Floppy Disk
`Drive
`
`
`
`
`
`Camera Power and Electronics
`
`Computer Bus
`--------------------------. W
`Disk Emulator
`
`Analog Out Card
`
`
`
`Watchdog Timer/Serial Interface
`
`Frame Grabber
`
`Computer
`
`Robot Controller
`
`Fig.2
`
`Google Ex. 1028, p. 3
`
`

`

`U.S. Patent
`
`Jan. 4, 1994
`
`Sheet 3 of 6
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`5,275,327
`
`
`
`Location of
`laser line
`
`Location of
`laser line
`
`Fig. 4b.
`
`Edges of
`molten
`weld pool
`
`Edge of gas
`Cup
`
`Google Ex. 1028, p. 4
`
`

`

`U.S. Patent
`
`Jan. 4, 1994
`
`Sheet 4 of 6
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`5,275,327
`
`
`
`Google Ex. 1028, p. 5
`
`

`

`U.S. Patent
`
`Jan. 4, 1994
`
`Sheet 5 of 6
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`5,275,327
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`
`
`Edge of weld
`groove
`
`Weld bead
`
`Welding
`torch gas
`Cup
`
`Molten weld
`pool
`
`Laser line
`
`Google Ex. 1028, p. 6
`
`

`

`U.S. Patent
`
`Jan. 4, 1994
`
`Sheet 6 of 6
`
`5,275,327
`
`
`
`Google Ex. 1028, p. 7
`
`

`

`1.
`
`NTEGRATED OPTICAL SENSOR
`
`5
`
`O
`
`CONTRACTUAL ORIGIN OF THE INVENTION
`The United States Government has rights in this
`invention pursuant to contract No. DE-AC07
`76ID01570 between the U.S. Department of Energy
`and EG&G Idaho, Inc.
`BACKGROUND OF THE INVENTION
`This invention relates to a sensor for welding opera
`tions and more particularly to a multifunction feedback
`control sensor for gas-tungsten and gas-metal arc weld
`ing operations.
`Automated welding requires a welding system capa
`ble of adapting to changing conditions encountered
`during the welding process. Many sensor systems have
`been developed to give automated welding systems the
`capability to adapt to variations in one parameter. For
`20
`example, Agapakis, J. E., et al. Welding Journal vol. 65,
`No. 11, pp. 33-41 (1986), describes laser striping for
`joint tracking, and Hanright, J., Welding Journal vol. 65,
`No. 11, pp. 19-24 (1986), discusses through-the-arc
`sensing techniques. Additionally, coaxial viewing of the
`25
`weld pool and infrared sensings are discussed in Rich
`ardson, R. W., et al., Welding Journal vol. 63, No. 3, pp.
`43-50 (1984), and Lukens, W. E., et al., Welding Jour
`nal vol. 61, No. 1, pp. 27-33 (1982), respectively.
`However, frequently it is desired to continuously
`monitor, in real-time, more than one parameter in the
`welding process, such as, the weld pool position and
`width, sensor-to-work piece distance and weld pool
`bead centerline cooling rate. Continuous monitoring of
`surfaces requires that light be reflected or emitted from
`those surfaces at sufficient strength so that attributes of
`35
`the surface can be detected by the imaging device. Ad
`ditional light, other than that which is required for
`imaging, shows up in the image as noise and degrades
`the quality of the image. In some cases, image degrada
`tion is so severe that the desired details or attributes
`within the image are lost and cannot be recovered. In
`the case of welding, the arc is a high luminosity light
`source that degrades the weld pool image to the extent
`that attributes of the weld pool and adjacent areas are
`unclear, unless light suppression techniques are used.
`45
`It is an object of this invention to provide an auto
`mated multifunction feedback control sensor for weld
`ing that is independent of significant operator interac
`tion.
`It is another object of this invention to provide a
`50
`multifunction feedback control sensor capable of mea
`suring weld pool position and width, sensor-to-work
`piece distance and weld bead centerline cooling rate.
`Additional objects, advantages and novel features of
`the invention will become apparent to those skilled in
`55
`the art upon examination of the following and by prac
`tice of the invention.
`SUMMARY OF THE INVENTION
`To achieve the foregoing and other objects, an inte
`grated optical sensor for arc welding having multifunc
`tion feedback control is provided. The integrated opti
`cal sensor consists of a computer automated system
`using a single charged coupled device (CCD) image to
`measure weld pool position, width and discrete temper
`65
`ature normal to molten weld pool/solidified weld bead
`interface. The integrated optical sensor also determines
`solidified weld bead profile and centerline cooling rate.
`
`5,275,327
`2
`Computer process information from this sensor is
`passed to a controlling computer for use in feedback
`control loops to aid in control of the welding process.
`The weld pool position and width data along with infor
`mation from a separate joint preview sensor is used to
`track the molten weld pool along a desired path in the
`weld joint. Solidified weld bead profile information is
`used as a basis to adjust welding process parameters to
`control welding torch standoff and adherence to weld
`bead fill strategies. Centerline cooling rate information
`is used to determine and control thermal input to the
`weld.
`BRIEF DESCRIPTION OF THE DRAWINGS
`The present invention is illustrated in the accompany
`ing drawings where:
`FIG. 1 is a schematic diagram of the integrated opti
`cal sensor system;
`FIG. 2 is a schematic diagram of the hardware con
`figuration for the integrated optical sensor system;
`FIG. 3a is a computer generated photograph of an
`unprocessed image output from the sensor.
`FIG. 3b shows a schematic drawing of the raw input
`image of FIG. 3a;
`FIG. 4a is a computer generated photograph of a
`processed image from the sensor showing laser line
`displacement;
`FIG. 4b shows a schematic drawing of the processed
`image of FIG. 4a,
`DETAILED DESCRIPTION OF THE
`INVENTION
`Referring now to FIG. 1, a schematic diagram of the
`integrated optical sensor (IOS) system is shown. The
`integrated optical sensor is comprised of a CCD camera
`10 with fixed optics consisting of a lens 12 and filter 14
`for imaging the weld pool and adjacent areas. The inte
`grated optical sensor relies on two techniques to sup
`press entry of direct arc light into the sensor. Suppres
`sion occurs by positioning the sensor so that the gas cup
`16 of the welding torch 18 acts as a mask to shield the
`CCD camera from light directly emitted from the weld
`ing arc, but allows arc light reflected or emitted infrared
`from the surface of the molten weld pool and adjacent
`areas to be used for imaging. Light intensities are fur
`ther attenuated and discriminated by using an extremely
`narrow, band pass or laser line filter 14. This filter al
`lows light in some narrow bandwidth, for example, at
`850 nanometers, plus or minus 0.5 nanometers (at half
`peak height), to pass through the filter and rejects all
`other wavelengths. Additionally, the filter has a trans
`mittance of approximately 45% in the band pass wave
`length, meaning that the incoming light intensities are
`cut by 55% after passing through the filter.
`Lens 12 is used to focus the incoming light onto the
`CCD camera detector. The field of view and magnifica
`tion may be further modified by using a extension tube
`(not shown) placed between the lens 12 and the CCD
`camera 10. The extension tube increases the magnifica
`tion and decreases the field of view, and allows the lens
`to be focused at the appropriate standoff distance from
`the weld bead. Different extension tubes can be used to
`allow the lens to be focused at different standoff dis
`tances. An iris in the lens can be manually adjusted to
`modify the quantity of light passing through the camera
`lens, or alternatively, the computer can control the lens
`and iris automatically.
`
`15
`
`30
`
`60
`
`Google Ex. 1028, p. 8
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`

`

`5,275,327
`4.
`3
`function of this card is to output analog voltages which
`The camera used in the IOS is light and compact and
`allow computer control of the gain, pedestal, and
`is unobtrusive to the normal operation of the welding
`gamma functions of the camera. Also, the card pro
`system. Preferably, the CCD camera is tilted off the
`duces a TTL output to control shutter operations of the
`torch axis between 5 to 15. The remote head contain
`ing the CCD detector is distant from the main camera 5
`diode laser.
`body by preferably approximately 2.3 meters. A camera
`The solid state disk emulator with daughter card is
`capable of emulating a hard disk drive. The emulator
`control unit 26 regulates the gain, pedestal, and gamma
`should preferably have up to 770 kilobytes of primary
`levels of the CCD camera. Additionally an enhancer is
`boot disk EPROM storage and up to 64 kilobytes of
`installed in the camera control unit to enhance the ana
`read/write secondary disk SRAM storage. The opera
`log video output signal of the CCD camera. Connection 10
`between the camera control unit 26 and the computer
`tional software and sensor calibration information are
`data acquisition system 24 is by a coaxial cable. The
`stored on these cards.
`There are four stages of data processing: acquisition,
`camera control unit can be modified to allow computer
`data validity check, unit conversion, and data output.
`control of the camera gain, pedestal and gamma func
`The acquisition process is further divided into three
`15
`tions.
`operations. Generally, each operation begins with the
`A diode laser 20 with striping optics is used to pro
`acquisition of a new image by the frame grabber. A
`duce a stripe transverse to the direction of welding. The
`portion of the image that is of interest, called a region of
`diode laser operates at the same wavelength frequency
`as the band pass filter 14, preferably approximately 850
`interest (ROI), is then transferred to the computer's
`RAM for processing. Once the data has been extracted
`nanometers, plus or minus 0.2 nanometers. The output 20
`power of the diode laser is adjustable to approximately
`from the regions of interest, a validity check is per
`540 mW continuous wave power. The heart of the
`formed. If the data is determined to be valid, it is con
`verted to the appropriate unit of measure and then sent
`diode laser is a high power multi-mode continuous
`out through the serial communication port to the pro
`wave injection diode laser. The diode laser has a Peltier
`cess controlling computer.
`cooling unit 22 capable of maintaining the specified 25
`output frequency over a temperature swing from 0 to
`FIGS. 3a and 4a, respectively illustrate the unpro
`cessed and processed computer generated photographs
`100 F. The diode laser has adjustable line generating
`optics capable of producing a stripe with dimensions of
`of a welding operation. Referring now to FIGS. 3b and
`4b, a detailed description of each data acquisition opera
`100 mm in length and 1 mm in width at a standoff dis
`tion is provided. The first acquisition operation extracts
`tance of 200 mm. Laser shuttering means 21 can be 30
`provided for operational safety. The laser shutter and
`the locations of the edges of the molten weld pool from
`ROI 1. The operation begins by transferring the pixel
`power control unit 28 can be controlled by the remote
`computer. In a preferred embodiment of the present
`intensities in ROI 1 to the computer's RAM. The loca
`tion of ROI 1 is shown in FIG. 4b and is determined by
`invention, two mirrors located beneath the diode laser
`the position of the welding torch gas cup. The position
`can be used to reflect the diode laser beam at the proper 35
`angle to the work piece 15. The angle of the laser stripe
`of the welding torch gas cup is determined in the second
`acquisition operation, which is described below. If the
`is dependent upon the sensor standoff distance and the
`accuracy required for the particular application. Prefer
`second acquisition operation does not find the welding
`torch gas cup, a default location is used. The edges of
`ably the angle of the laser stripe to the surface is be
`the molten weld pool are determined by scanning ROI
`tween 50 to 80 degrees.
`40
`1 in the y-direction (see FIG. 4b) using two image pro
`The computer data acquisition system 24 is com
`cessing techniques: thresholding and gradient detection.
`prised of several computer cards, including a disk emu
`Thresholding elevates all pixel intensities above a spe
`lator, analog output card, watchdog timer/serial inter
`face card, a digitizing frame grabber and a microproces
`cific level to the maximum intensity and all intensities
`below a specific level to the minimum intensity. The
`sor card. The hardware configuration for the integrated 45
`thresholding levels are determined by reading intensity
`optical sensor system is shown in FIG. 2. The frame
`levels in the weld pool area and setting the thresholding
`grabber card digitizes the video signal into discrete
`values representing the strength of the incoming video
`levels a determined amount above and below the weld
`signal. These values are stored in dual-ported memory
`pool intensity. Gradient detection locates the position in
`the ROI where a sharp gradient in image intensity oc
`located on the frame grabber board. Preferably, the 50
`board digitizes the video signal and stores an image in
`curs. Two gradients are found in ROI 1 and their loca
`one of two memory buffers at a rate of approximately 30
`tions are stored as x,y coordinate pairs which will be
`images per second. One complete image is referred to as
`transformed into part of the sensor's output. The loca
`a frame. A phase-locked loop circuit synchronizes the
`tion of the center of the weld pool (in the y-direction) is
`video timing of the frame grabber to the composite sync 55
`calculated using the two locations. The center location
`is stored for use by the second acquisition operation.
`of the video input signal.
`The first acquisition operation is continuously repeated
`The controlling microprocessor is a stand-alone sys
`until it is completed successfully.
`tem which self-boots on system power up. The image
`processing system operates without a keyboard and
`The second acquisition operation extracts three
`pieces of information, viz.: the location of the welding
`monitor, however, a monitor and keyboard can be used 60
`for display or diagnostic information during system
`torch gas cup edge; the location where the laser line
`integration. Welding process communications to and
`appears in the ROI; and the cooling rate of the solidified
`weld bead where a pre-determined temperature occurs.
`from the controller takes place through the watchdog
`The second acquisition operation begins by transferring
`timer/serial interface and proceeds at a rate of approxi
`the pixel intensities in ROI 2 into the computer's RAM.
`mately 10 Hz.
`ROI 2 is positioned over the weld pool center (in the
`The multifunction analog and digital I/O card
`y-direction) determined in ROI 1. A gradient detection
`(shown as 30 in FIG. 1) interfaces the camera control
`is performed to locate the edge of the gas cup and the
`unit and the laser shutter with the sensor computer. The
`
`65
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`Google Ex. 1028, p. 9
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`5
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`15
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`5,275,327
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`5
`state of the weld bead and heat affected zone, thereby
`center of the laser line in the x-direction of the image
`permitting control of post weld mechanical properties.
`(see FIG. 4b). The location of the gas cup edge is stored
`The foregoing description of a preferred embodiment
`for use by the first acquisition operation, while the loca
`of the invention has been presented for purposes of
`tion of the laser line is stored for use by the second
`illustration and description. It is not intended to be
`acquisition operation. Both are used to determine the
`exhaustive or to limit the invention to the precise form
`cooling rate of the weld bead by processing a row of
`disclosed, and obviously many modifications and varia
`pixel intensities down the center of ROI 2. This row is
`tions are possible in light of the above teaching. The
`processed to remove the intensities of the laser line and
`embodiments described explain the principles of the
`gas cup, leaving only pixel intensities of the solidified
`invention and practical application and enable others
`weld bead. These intensities are statistically processed
`skilled in the art to utilize the invention in various em
`to determine the cooling rate at a specific temperature,
`bodiments and with various modifications as are suited
`which the sensor receives from the robot computer via
`to the particular use contemplated. It is intended that
`the serial communication link. If no temperature value
`the scope of the invention be defined by the claims
`is received, a default value is used. The cooling rate for
`appended hereto.
`the location is then stored as a temperature change per
`The embodiments of this invention in which an exclu
`pixel which will be transformed into part of the sensor's
`sive property or privilege is claimed are defined as
`output. If the second acquisition operation cannot be
`follows:
`completed successfully, the sequence stops and is re
`1. A method for electronic data acquisition and multi
`turned to the first acquisition operation.
`function controlling of a welding operation, comprising
`20
`The third acquisition operation determines the loca
`the steps of:
`tion of the laser line at the edges of the weld bead from
`(a) positioning a laser and electronic imaging device
`two ROIS. The locations for ROI 3 and ROI 4, as
`in close proximity behind the path of a welding
`shown in FIG. 4b, are determined in the first and second
`torch so that the torch shields the imaging device
`acquisition operations. The centers of these Rols, in the
`from light directly emitted from the welding arc
`25
`x-direction, are placed at the laser line location deter
`site;
`mined in the first operation. ROI 3 and ROI 4 are
`(b) directing a laser stripe of a known wavelength
`placed, in the y-direction, at the upper and lower weld
`from the laser to a position traversing a weld bead
`bead edge, respectively, as determined in the first acqui
`site;
`sition operation. A gradient detection is performed on
`(c) filtering light reflected from the weld site by a
`30
`each ROI to locate the center of the laser line in each
`band pass filter of approximately the same wave
`ROI. The x-coordinate of the center of the laser line in
`length as the laser stripe;
`each ROI are stored so they can be transformed for the
`(d) acquiring images of the weld bead site by the
`sensor's output.
`electronic imaging device;
`When the three acquisition operations are completed,
`(e) processing and extracting from the acquired image
`the data is checked for validity. The pool edge locations
`the location of: the molten weld pool edges, the
`are compared with known boundary conditions and if
`welding torch gas cup edge, and the laser stripe;
`they are within these boundary conditions, the data are
`(f) analyzing the extracted information and calculat
`passed as valid. The laser line locations found in ROI 2
`ing data for controlling the welding process;
`(g) controlling the welding process based upon the
`and ROI 3 are checked to see that they are within a
`40
`preset boundary in the image area. If they fall within the
`calculated data.
`boundary, the data are passed as valid. A statistical
`2. The method of claim 1 further comprising the step
`correlation value is used to check the validity of the
`of determining the solidified weld bead profile and cen
`cooling rate information. This value is sent with the
`terline cooling rate from the measured information.
`cooling rate data as part of the sensor's output.
`3. The method of claim 2 wherein the solidified weld
`45
`bead profile information is used as a basis to adjust
`Once the data are validated, each set of data is con
`welding process parameters to control the torch stand
`verted to a standard unit of measure. The data obtained
`during the calibration of the sensor are used to convert
`off distance and adherence to weld bead fill design.
`pixel coordinates into distances in a standard unit of
`4. The method of claim 2 wherein the centerline
`measure. The weld pool edge locations are converted
`cooling rate information is used to determine and con
`50
`into distances from a center reference point in the image
`trol thermal input to the weld site.
`area. The laser line locations found in third acquisition
`5. The method of claim 1 wherein the information
`extracted from the acquired images is enhanced by
`operation three are converted into a work piece-to-ref.
`locating the position in the acquired image where a
`erence point distance. The reference point is determined
`sharp gradient in image intensity occurs.
`during sensor calibration. The cooling rate data are
`converted into a temperature change per unit distance
`6. The method of claim 5 wherein the enhanced im
`ages are further intensified by using a thresholding tech
`or a temperature change per unit time. The cooling rate
`nique which elevates all pixel intensities above an estab
`datum is accompanied by its statistical correlation. The
`lished threshold intensity level to the maximum inten
`data, converted to standard units, are sent through a
`sity level and reduces all intensities below a threshold
`serial communications link to the controlling computer
`60
`level to the minimum intensity level in order to empha
`for controlling the welding operation.
`size the intensity of the image.
`The pool position and width are used to control the
`7. The method of claim 1 wherein controlling the
`welding torch position relative to the weld pool, allow
`acquisition of information of step (d) and analysis of the
`ing the host control system to compensate for such
`information of step (f) is performed by a computer.
`phenomena as arc blow. The host welding system uses
`8. The method of claim 1 wherein the laser stripe is a
`the sensor standoff distance in the feedback loop to
`directed to the weld site at an angle between 50 and
`control the contact tip-to-work piece distance. Cooling
`80'.
`rate information is used to infer the final metallurgical
`
`35
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`55
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`65
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`Google Ex. 1028, p. 10
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`5
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`10
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`5,275,327
`7
`8
`13. The system of claim 10 further comprising means
`9. The method of claim 1 wherein the laser wave
`for cooling the laser to maintain a constant laser temper
`length and band pass filter are approximately 850 nano
`ature and output beam wavelength.
`eters.
`14. The system of claim 10 wherein the imaging sen
`10. A system for data acquisition and control of a
`sor is a charged coupled device camera.
`welding operation, comprising:
`15. The system of claim 14 further comprising a cam
`a. an electronic image sensor positioned in close prox
`era control unit to regulate the gain, pedestal and
`inity behind the path of a welding torch on a work
`gamma levels of the charged coupled device camera.
`piece so that the torch shields the imaging device
`16. The system of claim 10 wherein the computer
`from light directly emitted from the welding arc
`means comprises a disk emulator, analog output card,
`site;
`watchdog timer/serial interface card, digitizing frame
`b. means for creating a laser stripe transverse to a
`grabber and a microprocessor card.
`weld bead path, said laser stripe being a known
`17. The system of claim 10 wherein the lens means
`wavelength;
`and adjustment is controlled by a computer.
`c. lens means attached to the electronic image sensor
`18. The system of claim 10 further comprising an
`15
`for focusing the image;
`extension tube positioned between the image sensor and
`d. a band pass optical filter to limit the frequency of
`lens, said extension tube permitting the acquired image
`light reflected from the weld bead being imaged,
`to be focused at an appropriate standoff distance from a
`the band pass frequency corresponding to the
`work piece.
`wavelength of the laser stripe;
`19. The system of claim 10 wherein the image sensor
`e, computer means for acquiring and processing data
`is positioned at an angle of between 5' and 15" from the
`from the image and controlling the welding pro
`welding torch axis.
`20. The system of claim 10 further comprising means
`CSS,
`11. The system of claim 10 wherein the means for
`for directing the laser stripe to strike the work piece at
`creating the laser stripe is a continuous wave diode 25
`an angle of between 50 and 80.
`21. The system of claim 19 wherein the means for
`laser.
`directing the laser stripe is comprised of two mirrors
`12. The system of claim 11 wherein the diode laser
`generates a beam having a wavelength of approximately
`located between the laser and the work piece.
`850 nanometers.
`
`k
`
`20
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`65
`
`Google Ex. 1028, p. 11
`
`