I
`
`o
`
`o
`
`o
`
`hfrffir
`Office
`
`I
`
`PCrnBgg/01590
`2,t. 10. 99
`
`INVESTORIN PEOPLE
`
`The Patent Office
`Concept House
`Cardiff Road
`Newport
`
`r ocr t999
`
`I, the undersigned, being an officer duly authorised in accordance with Section 7aQ) nd Ø)
`of the Deregulation & Contracting Out Act 1994, to sign and issue certificates onbehalf of the
`Compholler-General, hereby certify that annexed hereto is a true copy of the documents ¡ts
`originally filed in connection with the patent application identified therein.
`
`In accordance with the Patenæ (Companies Re-regisnation) Rules 1982, if acompany named
`in this certificate and any accompanying documents hæ re-regisæred under the Companies Act
`1980 with the same name as that with which it was registered immediately before re-
`registration save for the substitution as, or inclusion as, the last part of the name of the words
`"public limiæd company" or their equivalents in Welsh, references to the name of the company
`in this certificate and any accompanying documents shall be treaæd æ references to the name
`with which it is so re-registered.
`
`In accordance with the rules, the words "public limiæd companyn may be replaced by p.l.c.,
`plc, P.L.C. or PLC.
`
`Re-registration under the Companies Act does not constitute a new legal entity but merely
`subjects the cornpany to certain additional company law rules.
`
`Signd
`
`DOCUMENT
`'RIORIT'
`SUBMITTED OR TRÂI.ISMITTED IN
`COMPLIANCE wlTH RULE l7.l(a) OR (b)
`
`?â9 - all
`ExHrBrr I OE I
`DAlE
`REPORTER
`PLnct Dcec. LIC
`
`stry
`
`PGS Exhibit 1081, pg. 1
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`;a Pate¡¡¿s Form.1,/77
`
`Pâtcnts À-t 1977
`(Rulc l,
`
`t
`
`1. You¡referencc
`
`2, Patent application numbcr
`(Tbe Patett OlFce uttllfll in tbts paft)
`
`3. Full name, address and postcode of rhe or of
`cach applicant (undqtíne alt summes)
`
`o
`
`Patents ADP numbar QJyou Þnout ie
`
`If rhe applicant is a corporatc body, give the
`counry/state of its incorporatio¡
`
`4. Title of the ir¡venrion
`
`ñ The
`tãtent
`Offiæ
`
`-r
`
`14.0123
`
`iilûrìï'€ Ee¡':û:?-i [r]17q?
`,:11,r??{'l ,ri: 0ü : is:iili . ;*
`
`The Paært Office
`
`Cardi.ffRoad
`Newport
`Gwent NP9 lRlI
`
`0l ocÏ 1ee8 9821277.2
`
`Geco AS
`Schlumberger House
`Solbraveien 23
`N-1370 Asker
`Norway
`
`-a._ -
`,'.-..-.(:
`Norway-r':'i'l-
`
`l.
`
`lÞfE PATENTOFFICE
`L
`- t (}cT 1q^
`HECEIVED BY POST;
`
`SEISIüC DATA ACQUISITION EQUIPMEI\II CTOIfIROL SYSTEM
`
`5. Name of your agetat GÍyou baue on¿)
`
`W B Batzer
`
`Geco-Prakla Technicat Services Inc
`Schlumberger House
`Buckingham Gate
`Gatwick
`West Sussex RH6 ONZ
`ì'-*-í;:- þ:; {.^C I
`
`Country
`
`Prio¡iry 3pplicedon ûuEbcr
`(íf you þnou ¡t)
`
`Datc of ñling
`(da!/montb/yar)
`
`Number of carlier application
`
`Detc of ñIing
`(day/montb/year)
`
`"Address for service" in the United Kingdorn
`co which all correspondencc shor¡td be sent
`(includlng tbe Instcode)
`
`o Patents ADP number 6ÍJ,ou þnou ít)
`6. lf you are dedaring pdority from one or more
`eadier patent applications, give t¡e country
`and the date of filing of rhe o¡ of each of thcse
`earlier applicatior¡s a¡¡d OI?ou knou it) tlJ,;e oÍ
`each application number
`
`7. If this application is divicted or otherwise
`derived from an ea¡lier UK application,
`give the number and the ñ.ling date of
`the earlier application
`
`and of
`suppofl
`
`8. Is a statement of
`to g¡ant
`â Patent
`this rcquest? (Ansuter'yes' íf:
`a) any applicant named in part j is ¡¡ot an inventor, or
`b) lbne ís an ínuentor u'bo ls not named as af,
`applicanl, or
`c) eny named applicant is a corporate body.
`See no¡e (d))
`
`'i:GCI'H.ffi .if iörn.¡.eU9æ¡i[¡40..',en'.,$0nfi
`
`7*ÉSU7,ii
`
`Patents Forrrr 7/77
`
`PGS Exhibit 1081, pg. 2
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`o
`
`l,atenls rorfll l/ / /
`
`9. Ënter the number of sheets for any of thc
`following items you are filing with this form.
`l)<¡ nor count copies of thc same document
`
`Continuation shects of this form
`DescriPtion 19
`
`5 I
`
`Claimrs)
`
`Abstr¿ct
`
`Drawing¡s.l 3 {_a Ð
`
`I 0. If you are also fìling any of the follon'ing,
`state how many against each item.
`
`Prioriry documents
`
`Translations of priority documents
`
`¡ Sratcment of inüentorship and right
`to gralnt of a patent (Pa¡ents Forrn 7n7)
`
`Requcst for preliminary examination
`and search (Parmts Fortn 9/77)
`
`1
`
`Request for substantivc examinarion
`(Paterts Form IO/77)
`
`Any other documents
`(please spect!)
`
`11
`
`$/Ve request the
`
`a
`
`on the basis of this appl¡cation.
`
`Signature
`
`Date
`
`30
`
`1998
`
`12. Name and da)îime tclcphone number of
`person to contrct in the United Kingdom
`
`W B Batzer OI293 556259
`
`Warning
`After an appltctttion for 4 patent bas been fìled, the CornptrolleÌ of tbe Patent Olftce utill consider whetþer publícatìon
`or communicatíon of tbe ínuenúon shot¿ld be probibited or restricted under Section 22 oÍ tbe Petents Act 1977. You
`wtll be infonned if it is necessarl to probíbít or restñct yotr inuention in tbis way. Furtbermore, if you llae ln tbe
`United Kingdont, Sectiort 23 oJ the Patents Act 1977 stops you Jrom appuing J'or a patent abroad uithout Íírst getting
`úritten Perntíssion from tbe Patent Offíce unless an eþplication bas been filed at least 6 ueel¿s beþreband in tbe
`United Kirtgdomfor a patentÍor tþe same inaentìon and either no direction probibit¡ng pubticatìon or
`commuflicc,tion bas been giuen, or ûny sucb direction ba.s been renoked.
`
`Notes
`a) If 1'r,ttt need belp tolíll ín tbisfonn or you haue any questions, please contact tbe Patent Offíce on 0645 50A505.
`b) Vrite yol,r altstt'ers in capitql letters ustng black ink or you may tyþe tbem.
`c) If there is not enouglt space for all rbe releuant details ott any part of tbis foffi, please continue on a seþarate
`sbeet of pttper and u)nte -see corttinuation sbeet" in tlze releuant pc.rt(s). Any co
`sbeet shottlcl oe
`&ttached to tÍ)¡s Íorm.
`d) Íf 1'ou baue anstaered 'Yes' Patents f'orn 7/77 u)ill need to be Íitect.
`e) Once yott baue Íilled in tbe fonn you mzßt retnentber to sigtr ancl date tt.
`, For details ol lbe Jee artd ways to pay please contact tbe patent Olfice.
`
`i¡eon{æ¡..t!"r,ffi iigggffi ili8ä:i.irniii.S0iÐ7iï2sü#i.:
`
`Patents For:nl. 1/77
`
`PGS Exhibit 1081, pg. 3
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`o
`
`SEISMIC DATA ACOUISITON EQUIPMENT CONTROL SYSTEM
`
`1
`
`BACKGROUND OF THE INVENTION
`
`This invention relates generally to systems for controlling seismic data
`
`acqu¡s¡tion equipment and particularly to a system for controlling a marine
`seismíc streamer positionÍng device.
`
`o
`
`A marine seismic streamer is an elongate cable-like structure, typically
`up to several thousand meters long, which contains arrays of seismic
`
`o
`
`sensors, known as hydrophones, and associated electronic equipment along
`its length, and which is used in marine seismic surveying. ln order to perform
`a 3D marine seismic survey, a plurality of such streamers are towed at about
`
`5 knots behind a se¡smic survey vessel, which also tows one or more seismic
`sources, typically air guns. Acoustic signals produced by the seismic sources
`are directed down through the water into the earth beneath, where they are
`reflected from the various strata. The reflected signals are received by the
`hydrophones, and then digitized and processed to build up a representation
`of the subsurface geology.
`
`The horizontal positions of the streamers are typically controlled by a
`deflector, located at the front end or "head" of the streamer, and a tail buoy,
`located at the back end or "tail" of the streemer. These devices create
`tension forces on the streamer which constrain the movement of the streamer
`and cause it to assume a roughly linear shape. Cross currents and transient
`forces cause the streamer to bow and undulate, thereby introducing
`deviations into this desired linear shape.
`
`The streamers are typically towed at a constant depth of approximately
`
`ten meters, in order to facilitate the removal of undesired "ghost" reflections
`from the surface of the water. To keep the streamers at this constant depth,
`
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`
`PGS Exhibit 1081, pg. 4
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`o control devices known as "birds", are typically attached at various points
`
`2
`
`O
`
`o
`
`along each streamer between the deflector end the tail buoy, with the spac¡ng
`between the birds generally varying between 20O and 400 meters. The birds
`have hydrodynamic deflecting surfaces, referred to as wings, that allow the
`position of the streamer to be controlled as it ís towed through the water.
`When a bird is used for depth control purposes only, it is possible for the bird
`to regularly sense its depth using an integrated pressure sensor and for a
`local controller within the bird to adjust the wing angles to maintain the
`streamer near the desired depth using only a desired depth value received
`from a central control sYstem.
`
`While the majority of birds used thus far have only controlled the depth
`of the streamers, additional benefits can be obtained by using properly
`controlled horizontally steerable birds, particularly by using the types of
`horizontally and vertically steerable birds disclosed in our published PCT
`lnternationalApplication No. WO 98/28636. The benefìts that can be
`obtained by using properly controlled horizontally steerable birds can include
`
`reducing horizontal out-of-position conditions that necess¡tate reacqu¡r¡ng
`seismic data in a particular area (i.e. in-fitl shooting), reducing the chance of
`tangling adjacent streamers, and reducing the time required to turn the
`seismic acquisition vesselwhen ending one pass and beginning another paSS
`
`during a 3D seismic survey.
`
`It is estimated that horizontal out-of-position conditions reduce the
`efficiency of current 3D seismic survey operations by between 5 and 10%'
`depending on weather and current conditions. \Nhile incidents of tangling
`adjacent streamers are relatively rare, when they do occur they invariably
`resull ln prolongecl vessel oownttme. lne loss oT eÎÎlclency asso
`wttn
`turning the seismic survey vesselwilldepend in large part on the seismic
`survey layout, but typical estimates range from 5 to 1O%- Simulations have
`
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`
`PGS Exhibit 1081, pg. 5
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`3
`
`concluded that properly controlled horizontally steerable birds can be
`expected to reduce these types of costs by approximately 30%.
`
`One system for controlling a horízontally steerable bird, as disclosed in
`uK Patent GB 2093610 B, is to utilíze a manually-operated central control
`system to transmit the magnitudes and directions of any required wíng angle
`changes to the birds. While this method greatly simplifies the circuitry needed
`within the bird itself, it is virtually impossible for thís type of system to closely
`regulate the horizontal positions of the birds because it requires manual input
`and supervísion. This becomes a particularly significant issue when a
`substantial number of streamers are deployed simultaneously and the
`number of birds that must be controlled goes up accordingly.
`
`Another system for controlling a horizontally steerable bird is disclosed
`in our published PCT lnternationalApplication No. wo 99129636. Using this
`type of control system, the desired horizontal positíons and the actual
`horizontal positions are received from a remote control system and are then
`used by a local control system within the birds to adjust the wing angles. The
`actual horizontal positions of the birds may be determined every s to 10
`seconds and there may be a 5 second delay between the taking of
`measurements and the determination of actual streamer positions. \Mile this
`type of system allows for more automatic adjustment of the bird wing angles,
`the delay period and the relatively long cycle time between positíon
`measurements prevents this type of control system from rapidly and efficienfly
`controlling the horizontalposition of the bird. A more deterministic system for
`controlling this type of streamer positioning device is therefore desired.
`
`improved method and apparatus for controlling a streamer positioning device
`
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`
`o
`
`:ì:iGbiHffi ::ïf öfi ï]iigiie94ûlf ]80.:::6$:istl07*20ü,iïi:i
`
`PGS Exhibit 1081, pg. 6
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`o
`
`4
`
`An advantage of the present invention is that the position of the
`streamer may be better controlled, thereby reducíng the need for in-fìll
`shooting, reducíng the chance of streamer tangling, and reducing the time
`needed to turn the seismic survey vessel.
`
`Another advantage of the present inventíon is that noise in marine
`seismic data associated with streamer position over-correction and streamer
`
`positioning errors can be significantly reduced.
`
`O
`
`oF THE TNVENTT.N
`
`',MMARY
`
`I
`
`The present invention involves a method of controlling a streamer
`positioning devíce configured to be attached to a marine seismic streamer
`and towed by a seismic survey vessel and having a wing and a wing motor for
`changing the oríentation of the wing. The method includes the steps of:
`
`obtaining an estimated velocity of the streamer positioning device, calculatíng
`a desired change in the orientation of the wing using the estimated velocity of
`the streamer positioning device, and actuating the wing motor to produce the
`desired change in the orientatíon of the wíng. The present invention also
`involves an apparatus for controlling a streamer positioning device. The
`apparatus includes means for obtainíng an estÍmated velocíty of the streamer
`positioning device, means for calculating a desired change in the orientation
`of the wing using the estimated velocity of the streamer positioning device,
`and means for actuating the wing motor to effectuate the desired change in
`the orientation of the wing. The invention and its benefìts wíll be better
`understood with reference to the detailed description below and the
`
`accompanying figures.
`
`PGS Exhibit 1081, pg. 7
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`BRIEF DESCßIPTION OF THE DRAWINGS
`
`5
`
`Figure 1 is a schematic diagram of a seismic survey vesseland
`
`associated seismic data acquisitíon equipment;
`
`Figure 2 is a schematic horizontal cross-sectional view through a
`marine seismic streamer and an attached streamer positioning device;
`
`Figure 3 is a schematic vertical cross-sectional view through the
`streamer positioning device from Figure 2; and
`
`Figure 4 is a schematic diagram of the local control system architecture
`of the streamer positioning device from Figure 2.
`
`DETAILED DESCRIPTION OF THE INVENT]ON
`
`ln Figure 1, a seismic survey vessel 10 is shown towing eÍght marine
`seismic streamers 12 that may, for instance, each be 3000 meters in length.
`The outermost streamers 12 in the array could be 700 meters apart, resulting
`in a horizontalseparation between the streamers of 100 meters in the regular
`horizontal spacing configuration shown. A seismic source 14, typically an
`
`airgun or an array of airguns, is also shown beíng towed by the seismic
`survey vessel 10. At the front of each streamer 12 is shown a deflector 16
`and at the rear of every streamer is shown a tail buoy 20. The deflector 16 is
`used to horizontally posítion the end of the streamer nearest the seismic
`survey vessel 10 and the tail buoy 20 creates drag at the end of the streamer
`farthest from the seismic survey vessel 10. The tension created on the
`sersmrc streamer by the deïlector 1ti ano Ine tail Þuoy zu results rn tne
`roughly linear shape of the seismic streamer 12 shown in Figure 1
`
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`
`PGS Exhibit 1081, pg. 8
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`o
`
`o
`
`o
`
`6
`
`Located between the deflector 16 and the tailbuoy 20 are a plurality of
`streamer positioning devices known as birds 18. Preferably the birds 1B are
`both vertically and horizontally steerable. These birds 18 may, for instance,
`be located at regular intervals along the streamer, such as every 200 to 400
`meters. The vertically and horizontally steerable birds 18 can be used to
`constrain the shape of the seismic streamer 12 between the deflector 16 and
`the tail buoy 20 in both the vertical (depth) and horizontal directions.
`
`ln the preferred embodiment of the present invention, the control
`system for the birds 18 is distributed between a global control system 22
`located on or nearthe seismic survey vessel 10 and a local control system
`located within or near the birds 18. The global control system 22 is typically
`connected to the seismic survey vessel's navigation system and obtains
`estimates of system wide parameters, such as the vessel's towing direction
`and velocity and current direction and velocity, from the vessel's navigation
`
`system.
`
`The most important requirement for the control system is to prevent the
`streamers 12 from tangling. This requirement becomes more and more
`
`important as the complexity and the total value of the towed equipment
`increases. The trend in the industry is to put more streamers 12 on each
`
`seismic survey vessel 10 and to decrease the horizontal separation between
`them. To get better control of the.streamers 12, horizontal steering becomes
`necessary. lf the birds 18 are not properly controlled, horizontal steering can
`increase, rather than decrease, the likelihood of tangling adjacent streamers.
`
`Localized current fluctuations can dramatically influence the magnitude of the
`side control required to properly position the streamers. To compensate for
`
`these localized current fluctuations, the inventive control system utilizes a
`distributed processing control architecture and behavior-predictive model-
`based control logic to properly controlthe streamer positioning devices.
`
`PGS Exhibit 1081, pg. 9
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`o
`
`o
`
`o
`
`7
`
`ln the preferred embodiment of the present invention, the globaf control
`system 22 monitors the aclual positions of each of the blrds 18 and is
`programmed with the desired positions of or the desíred minimum separations
`
`between the seismic streamers 12. The horizontal positions of the birds 1B
`can be derived, for instance, using the types of acoustic positioning systems
`described in our U.S. Patent No. 4,992,990 or in our PCT lnternational Patent
`Application No. WO 98/21163. Alternatively, or addítionally, satellite-based
`
`global positioning system equipment can be used to determine the p.ositions
`of the equipment. The vertical positions of the birds 1B are typically
`monitored using pressure sensors attached to the birds, as discussed below.
`
`The global control system 22 preferably maintains a dynamic model of
`
`each of the seismic streamers 12 and utilizes the desired and actual positions
`of the birds 18 to regularly calculate updated desired vert¡cal and horizontal
`
`forces the birds should impart on the seisrnic streamers 12 to move them from
`theír actual positions to their desired positions. Because the movement of the
`
`seismic streamer 12 causes acoustic noise (both from seawater flow past the
`bird wing structures as well as cross current flow across the streamer skin
`itself), it is important that the streamer movements be restrained and kept to
`the minimum correction required to properly position the streamers. Any
`streamer positíoning device control system that consistently overestimates
`the type of correction required and causes the bird to overshoot its intended
`position introduces undesirable noise into the se¡smic data being acquired by
`the streamer. ln current systems, this type of over-correction no¡se is often
`balanced against the "noise" or "smearing" caused when the seismic sensors
`
`in the streamers 12 are displaced from their desired posit¡ons.
`
`The global control system 22 prelerably cafculates the desired vertical
`and horizontal forces based on the behavior of each streamer and also takes
`into account the behavior of the complete streamer affay. Due to the
`relatively low sample rate and time delay associated with the horizontal
`
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`
`PGS Exhibit 1081, pg. 10
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`o posit¡on determination system, the global control system 2? runs position
`
`I
`
`o
`
`o
`
`predictor software to estimate the actual locations of each of the birds 1B'
`The global control system 22 also checks the data received from the vessel's
`navigation system and the data will be filled in if it is missing- The interface
`between the global control system 22 and the local control system will
`typically operate with a sampling frequency of at least 0.1 Hz. The global
`control system 22 will typically acquire the following parameters from the
`vessel's navigation system: vesselspeed (m/s), vessel heading (degrees),
`current speed (m/s), current heading (degrees), and the location of each of
`the bírds in the horizontal plane in a vesselfìxed coordinate system. Current
`speed and heading can also be estimated based on the average forces acting
`on the streamers 12 by the birds 18. The global control system 22 will
`preferably send the following values to the local bird controller: demanded
`vertical force, demanded horizontal force, towing velocity, and crosscurrent
`
`veloc¡ty.
`
`The towing velocity and crosscurrent velocity are preferably "water-
`referenced" values that are calculated from the vessel speed and heading
`values and the current speed and heading values, as well as any relative
`movement between the seismic survey vessel 10 and the bird 18 (such as
`whíle the vessel is turning), to produce relative velocities of the bird 1B with
`respect to the water in both the 'in-line" and the "Gross-line" directions'
`Alternatively, the global control system 22 could provide the local contfol
`system with the horizontal velociÇ and water in-flow angle. The force and
`velocity values are del¡vered by the global control system 22 as separate
`values for each bird 1E on each streamer 12 continuously during operation of
`the control system.
`
`The "water-referenced" towing velocity and crosscurrent velocity could
`alternatively be determined using flowmeters or other types of water velocity
`sensors attached directly to the birds 18. Although these types of sensors are
`
`PGS Exhibit 1081, pg. 11
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`9
`
`typically quite expensive, one advantage of this type of velocity determination
`system is that the sensed in-line and cross-line velocities will be inherently
`compensated for the speed and heading of marine currents acting on said
`streamer positioning device and for relative movements between the vessel
`1O and the bird 18.
`
`Figure 2 shows a type of bird 1B that is capable of controlling the
`position of seismic streamers 12 in both the vertical and horizontal directions
`A bird 1B of this type is also dísclosed in our PCT lnternational Application
`No. WO 98/28636. While a number of alternatíve designs for the vertically
`and horizontally steerable birds 1B are possible, including those utilizing one
`full-moving wing with ailerons, three full-mov¡ng wings, and four full-moving
`wings, the independent two-wing principal is, conceptually, the simplest and
`most robust design.
`
`ln Fígure 2, a portíon of the seismic streamer 12 is shown with an
`attached bird 18. A communication line 24, which may consist of a bundle of
`fÌber optic data transmíssíon cables and power transmissíon wires, passes
`along the length of the seismic streamer 12 and is connected to the seismic
`sensors, hydrophones 26, that are distributed along the length of the
`streamer, and to the bird 18. The bird 1B preferably has a pair of
`independently moveable wings 28 that are connected to rotatable shafts 32
`that are rotated by wing motors 34 and that allow the orientation of the wings
`28 with respect to the bird body 30 to be changed. When the shafts 32 of the
`bird 1B are not horizontal, this rotation causes the horizontal orientation of the
`wings 28 to change and thereby changes the horizontalforces that are
`applied to the streamer 12by the bird.
`
`The motors 34 can consist of any type of device that is capable of
`changing the orientation of the wings 28, and they are preferabry either
`electric motors or hydraufic actuators. The local control system 36 controls
`
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`PGS Exhibit 1081, pg. 12
`PGS v. WesternGeco (IPR2014-00688)
`
`

`
`10
`
`o the movement of the wíngs 28 by calculating a desired change in the angle of
`
`the wings and then selectively driving the motors 34 to effectuate this change.
`While the preferred embodiment depicted utilizes a separate motor 34 for
`each wíng 28, it would be also be possible to independently move the wings
`2B using a single motor 34 and a select¡vely actuatable transmission
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`mechanism.
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`When the bird 1B uses two wings 28 to produce the horízontal and
`vertical forces on the streamer 12, the required outputs of the local control
`system 36 are relatively simple, the directions and magnitudes of the wing
`movements required for each of the wings 28, or equivalently the magnitude
`and direction the motors 34 need to be driven to produce this wing
`movement. While the requíred outputs of the local control systern 36 for such
`a Nvo full moving wing design is quite simple, the structure and operation of
`the overall system required to coordinate control of the device is relatively
`complicated.
`
`Figure 3 shows a schematic vertical cross-sectional view through the
`streamer positioning device shown in Figure 2 that will allow the operation of
`the inventive controlsystem to be described in more detail. The components
`of the bird 18 shown ín Figure 3 include the wings 28 and the body 30. Also
`shown in Figure 3 are a horizontalcoordinate axis 38 and a vertical
`coordinate axis 40, During operation of the streamer Position¡ng control
`system, the global control system 22 preferably transmits, at regular intervals
`(such as every five seconds) a desired horizontal force 42 and a desired
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`vertical force 44 to the local control system 36.
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`combined within the local control system 36 to calculate the magnitude and
`direction of the desired total force 46 that the global control system 22 has
`instructed the localcontrolsystem to apply to the streamer 12. -fhe global
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`PGS Exhibit 1081, pg. 13
`PGS v. WesternGeco (IPR2014-00688)
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`control system 22 could alternatively provide the magnitude and direction of
`the desired total force 46 to the local control system 36 instead of the desired
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`horizontal force 42 and the desired vertical force 44.
`
`While the desired horizontal force 42 and the desired vertical force 44
`are pre'ferably calculated by the global control system 22,ilis also possible
`for the local control system 36 in the inventive control system to calculate one
`or both of these forces using a localized displacemenVforce conversion
`program. Thís type of localized conversion program may, for instance, use a
`look-up table or conversion routine that associates certain magnitudes and
`directions of vertical or horizontal displacements with certain magnitudes and
`directions of changes in the vertical or horizontal forces required. Using this
`type of embodiment, the global control system 22 can transmit location
`information to the local control system 36 instead of force information.
`lnstead of the desired vertical force 44, the global control system 22 can
`transmit a desired vertical depth and the local control system 36 can calculate
`the magnitude and direction of the deviation between the desired depth and
`the actual depth. Similarly, instead of transmittíng a desired horizontal force
`42,lhe global control system 22 can transmit the magnitude and direction of
`the displacement between the actual horizontal position and the desired
`horizontal position of the bird 18. One advantage to this alternative type of
`system is that the required vertical force can be rapidly updated as the local
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`control system receives updated depth information from the integrated
`pressure sensor. Other advantages of this type of alternative system include
`reducing communication traffìc on the communication l¡ne 24 and simplifying
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`the programming needed to convert the measured vertical andlor horizontal
`displacements into corresponding forces to be applied by the birds 18.
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`When the local control system 36 has a new desired horizontal force
`42 and desired vertical force 44 to be applied, the wíngs 28 will typically not
`be in the proper orientation to provide the direction of the desired total force
`
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`PGS Exhibit 1081, pg. 14
`PGS v. WesternGeco (IPR2014-00688)
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`o ' 46 required. As can be seen in Figure 3, the wings 28 introduce a force into
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`the streamer 12 along an axis perpendicular to the rotational axis of the wings
`28 and perpendicular to the streamer. This force axis 48 is typically not
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`12
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`properly aligned with the desired total force 46 when new desired horizontal
`and verticalforce values are rece¡ved from the global control system 22 or
`determined by the local control system 36 and some rotation of the bird 1B is
`requíred before the bird can produce this desired total force 46. As can be
`seen, the force axis 48 is directly related to the bird roll angle, designated in
`Figure 3 as g.
`
`The local controlsystem 36 optimizes the control process by projecting
`the desired total force 46 onto the force axis 48 (i.e. multiplying the magnitude
`of the desired total force by the cosine of the deviation angle 50) to produce
`an intermediate desired force 52 and then adjusting the wing common angle
`ø (the angle of the wings with respect to the bird body 30, or the average
`angle if there is a non-zero splay angle) to produce this magnitude of force
`along the force axis. The calculated desired common wing angle ís compared
`to the current common wing angle to calculate a desired change in the
`common wing angle and the wing motors 34 are actuated to produce this
`desired change in the orientation of the wings.
`
`A splay angle is then introduced into the wings 28 to produce a
`rotational movement in the bird body 30 (i.e. to rotate the force axis 48 to be
`aligned with the desired totalforce 46). The splay angle is the difference
`between the angles of the wings 28 with respect to the bird body 30. As the
`bird body 30 rotates and the force axis 48 becomes more closely aligned with
`the desired total force 46, the bird roll angle and the bird roll angular velocity
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`angle is incrementally increased until the intermediate desired force 52 is in
`the same dírection and of the same magnitude as the desired total force. The
`local control system 36 carefully regulates the splay angle to ensure that the
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`PGS Exhibit 1081, pg. 15
`PGS v. WesternGeco (IPR2014-00688)
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`streamer is stable in roll degree of freedom. The calculated common wing
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`angle and the splay angle are also regulated by the local controlsystem 36 to
`prevent the wings 28 from stalling and to ensure that the splay angle is
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`prioritized.
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`When using the type of birds described in our published PCT
`lnternationalApplication No. WO 98/28636, where the bird 1B is rigidly
`
`attached, and cannot rotate with respect, to the streamer 12, it is important for
`the control system to take the streamer twist into account. lf this is not taken
`into account, the bird 18 can use all of its available splay angle to counterthe
`twist in the streamer 12. The bird 18 wíll then be unable to reach the
`demanded roll angle and the generated force will decrease. The inventive
`
`control system incorporates two functions for addressing this situation, the
`anti-twist function and the untwist function.
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`ln the anti-twist function, the streamer twist is estimated by
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`weÍghtfunction filtering the splay angle measurements instead of simply
`averaging the splay angle measurements to improve the bandwidth of the
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`eslimation. The anti-twist function engages when the estimated twist has
`reached a criticalvalue and it then overrides the normal shortest path control
`of the calculated roll angle. The anti-twist function forces the bird 18 to rotate
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`in the opposite direction of the twist by adding +/- 180 degrees to the
`demanded roll angle. Once the twist has been reduced to an acceptable
`
`value, the anti-twist function disengages and the normal shortest path
`calculation is continued.
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`The untwist function is implemented by the global control system 22
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`regular intervals or when the splay angle has reached a critical value, the
`globalcontrol system 22 instructs each local control system 36 to rotate each
`bird 18 in the oppos¡te direction of the twist. The number of revolutions done
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`PGS Exhibit 1081, pg. 16
`PGS v. WesternGeco (IPR2014-00688)
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`o by each bird '18 is monitored and the untwist function is disengaged once the
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`twist has reached an acceptable level
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`Figure 4 is a schematic diagram of the architecture of the local control
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`system 36 for