US3554084A - Redundant force summing servo unit - Google Patents

Redundant force summing servo unit Download PDF

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Publication number
US3554084A
US3554084A US683994A US3554084DA US3554084A US 3554084 A US3554084 A US 3554084A US 683994 A US683994 A US 683994A US 3554084D A US3554084D A US 3554084DA US 3554084 A US3554084 A US 3554084A
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pressure
fluid
piston
power
valve
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US683994A
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Robert F Rasmussen
John C Taylor
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Honeywell Inc
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Honeywell Inc
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B9/00—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B18/00—Parallel arrangements of independent servomotor systems
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
    • G05D1/0055—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots with safety arrangements
    • G05D1/0077—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots with safety arrangements using redundant signals or controls

Definitions

  • MmneapolfsiMmn' ABSTRACT The servosystem which will tolerate failure in a corporat'on of Delaware two of its four redundant channels and still be operational consists of four identical redundant units.
  • the force outputs of the [54] REDUNDANT FORCE SUMMING SERVO UNIT four redundant units are summed together, by means of a 11 Claims 6Drawin H S summing hnk or member, with the resultant force on the v g g member being applied to a control valve of a fluid operated [52] US. CL 91/3, motor which is a low resistive load ,9 3
  • the input signal to each redundant unit is an electrical [51] Int.
  • the purpose of the pressure sensor piston is to provide long term hydraulic pressure equalization on all'of the jet pipe receiving holes.-For example, ideally if each of the four redundant units was identical a'ndr'eceived-the' same input signal,
  • Each redund ant channel of the servo in one embodiment additionallyincludesa third piston arrangement which acts as a failure monitorflf a hardover faiiuretorra loss of input or feedback) occurred in any individualredundant channel, the pressure differential on both its mod and sensor pistons would build up to a large value. Both-pistons would move in response to the pressureHowever, the mod piston isconstrained by the summinglink, which is beingheld in place (within a small erfor) by the other redundant units; whereas the monitor pressure sensor piston is free to move, and does so, until it trips a failure switch which disengages the particular redundant channel or unit as by removing hydraulic pressure.
  • fly-by-wire control apparatus incorporating duplicate or redundant units.
  • the term fly-by-wire may be .visualized as a structural departure with respect to a conventional aircraft having force transmitting control cables extending between the control stick operated by the pilot and the-control surface or control surface actua I tor. ln-the fly-by-wire apparatus," such cables are omitted and signals are t'akendirectly from the pilots stick or other signal sources for'operating a motor to position the actuator.
  • One object of this invention therefore is to provide an improved apparatus with channel redundancy and with a minimum requirement for cross channel monitoring.
  • Another object of this invention is to provide for channel I redundancy monitoring with a simplein-
  • a further object of this invention is'to provide redundant channels each having a separate force summed servo which servos coact on a common'output member to minimize movement of the output member upon occurrence of a failure.
  • a further object of the invention is to provide in each of multiple redundant channels a hydraulic or fluid pressure equalization monitor arrangement to minimize channel mistracking.
  • I j I' A further object of the invention is to provide for each of the redundant channels an individual improved malfunction equalization disengage monitor arrangement;
  • FIG. 3 is a block diagram of a redundant channel along with the summing link or summing member for the four channels;
  • FIG. 4 is a block diagram of a second form of jet pipe equalization pressure arrangement and monitor failure control
  • FIG. 5 is a schematic diagram of the arrangement of FIG. 4.
  • FIG. 6 is a schematic of a modified form 'of equalizer piston-
  • four identical channels which receive like control signals, each include a force summed-fluid servo.
  • the servos may have separate fluid sources or there may be a lesser number of fluid sources than servoswith suitable pressure operated switching means for each source for switching out a failed source from a servo and switching in an unfailed source to the servo, for example.
  • the four servos are utilized to drive a common output member with each servo driven directly from operation of a member of one of the redundant channels. Multiple force summing minimizes the output link response to a failure of one channel thus allowing a simple failure monitoring arrangement to disengage a failed channel.
  • a simple pressure equalization arrangement for a fluid servo is used in each channel to minimize the mistracking due to mismatching of inputs or tolerances within the servo.
  • a jet pipe valve utilizing an electrically driven moveable orifice is used to provide-proportional control and also to minimize hydraulic contamination effects which sometimes occur in other arrangements.
  • a simple hydraulic pressure sensor piston monitors the differential pressure across each individual servo power piston and feeds back a time integrated and limited signal to the torque motor output which reduces the servo differential pressure and thereby channel mistracking.
  • the primary positional feedback to the torque motor linkage that positions the jet pipe is obtained from the common multiple force summing member that is positioned by the four redundant servos.
  • a redundant control system includes a plurality of redundant channels A, B, C, and D. Since the channels are similar, a description of one will suffice for a description of all.
  • an electrical variable signal source such as control transducer 17 operated by movement of a member such as the control stick of an aircraft supplies the control signal in each case to a demodulator amplifier 19 which in turn through a shaping network 20 supplies a control signal to summing device 21.
  • the summing device also receives control signals from stabilization and control augmentation systems (not shown) through conductor 22.
  • the signal from summing device 21 is transmitted by conductor 23 to a servoamplifier 25.
  • the output of the amplifier 25 reversibly controls the operation of a conventional torque motor 26 which through motion transmission means 27 controls the operation of a moveable servo control member that differentially ports fluid to the ends of a piston of a servo 38.
  • the piston under control of the fluid applied thereto operates through piston rod 61 a common member of the four channels, and the common member 40 has an output 41 that operates for example the control valve of a main actuator for a control surface.
  • the movement of the servopiston and its rod 61 to force summing member 40 is also supplied in a feedback arrangement of the force transmission type to a force summing arrangement within servo 38.
  • the output from the force summing arrangement within servo 38 is transmitted to the moveable servocontrol member.
  • the force summing arrangement within servo 38 receives an input over transmission means 48, of the force type, from a pressure equalization arrangement 49.
  • the equalization arrangement 49 and a monitor 51 receives as inputs thereto the pressure across the mod piston in servo arrangement 38 to be described.
  • FIG. 2 shows a force summed fluid-type servomotor 38 for one channel.
  • Servo 38 includes a torque motor 26 (that receives the variable transducer signal) having an output arm 54 which through a link 59 operates to variably displace a jet pipe or moveable servocontrol member 52.
  • the jet pipe 52 receives pressure fluid through a solenoid operated engage valve and conduit 51 from a fluid pressure source P.
  • a return 53 is provided from the discharge of jet pipe 52.
  • the jet pipe 52 coacts with two holes or ports 57, 58 which normally receive equal fluid pressure discharge from the jet pipe 52.
  • the holes 57, 58 communicate by suitable conduits to opposed sides of a mod piston 60.
  • Operation of the torque motor arm 54 and its connected link 59 in either direction according to the transducer signal displaces the jet pipe 52 to cause reversible movement of the mod piston 60.
  • An output rod 61 of the mod piston 60 connects to a mod piston summing link or summing member 63 which may be used to position a control valve of a main actuator, now shown.
  • the jet pipe 52 is repositioned toward its normal position by a feedback arrangement comprising summing member 63 on common member 40, a feedback spring 64 and link 65 connected to torque motor arm 54.
  • the redundant servos operated member 63 thus exerts supervision of the feedback to jet pipe 52.
  • a hydraulic fluid cylinder-piston type monitor having a piston 67 has applied to opposite ends thereof pressure.
  • the fluid is conducted to the ends through suitable orifices 62 or restrictors in subconduits connected with main conduits extending to opposite sides of the mod piston 60.
  • the orifices provide a time delay to operation of the piston 67 following initial displacement of mod piston 60.
  • Movement of the monitor piston 67 is transmitted through a feedback spring 69 (thus thrnnoh a force or imoositive feedback member) to the torque motor arm 54 to reposition jet pipe 52 to thereby provide pressure equalization fromjet pipe 52 on the holes or ports 57. 58.
  • the hydraulic fluid clinder-piston monitor having piston 67 operates through a suitable connection a disengage limit switch 72 for opening the electrical circuit through a solenoid operated engage valve 50 permitting the valve to close by suitable means such as a spring to interrupt the flow offluid to the adjustable jet pipe 52, thus indicating a failure in the particular channel involved.
  • FIG. 3 is an analysis block diagram of the force summed servo 38 of FIG. 2 wherein the electrical torque motor 26 receives a variable voltage signal over a conductor from amplifier 25 FIG. 1.
  • the torque motor as a transducer converts the electrical input to a mechanical torque output proportional to its electrical input. Through its arm 54 and connecting link 59, it initially positions the jet pipe 52 a distance proportional to the difference between the torque motor output and the two feedback spring (64 and 69) forces.
  • the jet pipe 52 varies the fluid pressure in receiving holes 57 and 58, proportional to its displacement, whereby the mod piston 60 is positioned in inches per second in accordance with the flow resulting from that pressure differential which is applied to its opposite sides.
  • the piston 60 moves in its cylinder in accordance with the integral of the time period of the differential pressure and resulting rate of flow, and through its rod 61 positions the mod piston summing link 63 and member 40 which operates the feedback spring 64 to provide a force feedback proportional to'thc displacement of the summing link 63 from the neutral position.
  • the force on spring 64 varies the normal dimension or shortest distance between its output-input points. This force is transmitted through the connecting link 65 to the force summing point 66 which may be considered the remote end of arm 54.
  • the displacement of pressure sensor monitor piston 67 is supplied to the disengage on-off limit switch 72 which operates as will be described hereinafter to break the circuit through the operating solenoid of engage valve 50 thereby terminating the flow of fluid from the pressure source P to the jet pipe 52.
  • the switch 72 also controls the energization of an indicator for notification to the pilot of such failure in the channel.
  • each channel torque has similar feedback provisions as that in channel A.
  • FIG. 4 thus hasreference characters corresponding to those in FIG. 3.
  • valve In addition to the mod piston pressuresensing or responsive switches 72 controlling the solenoid engage valve 50, the valve may additionally be controlled from engageand monitor-circuits to be described.
  • FIG. 4 consequentlyincludes logic statements which will hereinafter be reviewed.
  • FIG. 5 shows the force summed servo'with the mechanical feedback of FIG. 4shown indetail.
  • the features common with FIG. 2 havethe same reference characters.
  • FIG. 5 since it presentsmetely. novel electrical circuits over material previously'considered, will be described concurrently with its operation, thus momentary closing of a manually operable start monitor switch 80 upper Ieft'closes the'circuit from a DC voltage source (not shown), conductor 81, switch 80, conductor 82, conductor 83,: presently closed solenoid operated switch 84, conductor 85, through a pull-in electrical winding 86 of a push-type solenoid, conductor 87 to DC return.
  • the engage valve 50 as shown is in closed. position whereby pressureifrom the source P cannot be transmitted to the jet pipe 52.
  • valve moves rightward in the'FlG. thus permitting pressure fluid to be supplied to the jet pipe 52 and concurrently opening the circuit through switch" 84 by an extension of'the valve and valve 50 remains open by the following arrangement.
  • Pressure monitor disengage switch 72 as shown consists of four relatively moveable'end. mounted members twoof which, 90, 91 are elongated to engage with shoulders on moveable plungers 93, 94, of the mod piston pressure monitor.
  • Each of the separate plungers 93, 94 have engaged therewith suitable outwardly biasing springs 95, 97. It is evident that when pressure fluid through suitable conduitsshown, isadmitted. to one end of each of the plungers 93 and 94 thatthenormal pressure in ports 57, 58 as transmitted by the conduits compress the biasing springs 95, 97 causing the, operable inner switch members 90, 91 to contact each other.
  • the outer switch contacts 98, 99 which normally engage their respective inner contacts 90, 91 remain so engaged.
  • I I j Concerning the operation of thepressuremonitor disengage switch 72, in the event thatthere. has been a failed operation malfunction in signal operated-amplifier 25 of channel A for example whereas the remaining channels'have operated, motion is applied-in 'channelA through the force summing link 40 and rod 61 to piston moving the cylinder feedbackflat spring 64 and displacing the jet pipe 52, lwhich-has notorque applied thereto from torque 26, in accordance with the dis spring 119.
  • the'chamber- 113' includes a washer '1 18' biased by a preloaded coil spring. 120.
  • the arrangement is placement of the output member 40 or summing linkt63.
  • This unrestricteddisplacement ofpipe 52 results he large pressure in one or the other of holes or ports 57, 58 which can approximate percent of the total pressure P, resulting in a large displacement say of plunger 94 relativetoplunger 93 or viceversa and as to plunger 94 engaging switcharrn thereby opening the electrical circuit between outer contact 98 and inner contact 90 or as to plunger 93 beingoperated disengag ing outer contact 99 and inner COIIMCI-QLIIICI'CIJ ⁇ !
  • ble auxiliary spring means 89 connected thereto aided by the pressure from the hydraulic power source.
  • the spring biased,.mod'piston pressure equalizer piston 67 is supplied'with fluid through'a 'rest rictor 62 to limit' the flow rate thereto so thatitoperateson a long term basis.,ln one mode of :operation of thepressure' equalizer piston 67, in the event that the A channel mbd piston 60 is jammed and will notmove, a differential pressu're on the opposite ends of the mod piston 60 for an extended time period occurs.
  • the equalizer piston67 because of the presence over the time period of the differential pressure, is displaced and through its spring connection 69 will return the jet pipe '52 to normal position where it applies equal pressure to the two openings 57, 58 and thus toboth ends of the mod piston.
  • Thecircuit between conductor 88 and outer contact 99 of limit switch 72 as stated includes a manually operable engagedisengage switch 104 so that the channel may be also manually disengaged. It is moved to closed position following momentary operation. of switch 80 to hold the solenoid valve 50in the open or engaged position. 1
  • the disengage logic is tabulated.
  • the electrical engage circuit for valve 50 is opened between contacts 90, 91, if c, c be less than .5 P,.
  • the circuit is opened between contacts 90,98 of the limit switch 72 if c, c, be greater than .8 P, Finally, if 0 c be greater than .8 P, the engage circuit is opened at contacts 91, 99. In other words, for the first condition, the inner contacts 90, 91, will become disengaged or are not closed. For the second condition, outer contact 98 and inner contact 90 will be disengaged.
  • outer contact 99 and contact 91 will be disengageddn other words, the solenoid winding for the engage valve 50 will be deenergized if there is very low pressure supplied to the mod piston 60 by the jet pipe 52. Also, if the pressure be ex cessive on one side of the mod piston relative to the other. either switch contacts 98,. 90 or 99, 91 will be disengaged.
  • FIG. 6 shows a modified form of cylinder-piston equalizer 110, where the cylinder has a small diameter portion Ill Endchamber 112 includes a washer 1l7'which abuts one end of chamber 112 while subject to the force of a prestressed coil such that the washers 1'17 and 118 with no pressure applied to conduits c, and c apply no force to the piston 67.
  • the cylinder has a small diameter portion Ill Endchamber 112 includes a washer 1l7'which abuts one end of chamber 112 while subject to the force of a prestressed coil such that the washers 1'17 and 118 with no pressure applied to conduits c, and c apply no force to the piston 67.
  • the conduits c, c when a differential pressure is applied to the conduits c, c, the
  • Each of the servo amplifiers, such asamplifier 25in channel A, for the forcesummed fluid servos receive a similar electrical control signal.
  • the multiple mod pistons are normally linked together to a common output member 63.
  • the mod pistons normally or ideally have the same operation.
  • the null of each of the servounits will vary in accordance with manufacturing tolerances, material variations, etc.
  • a differential pressure sensor equalizer is connected to the corresponding output cylinder to have applied thereto the differential pressure on a mod piston.
  • Either soft or hardover failures are detected directly by the failure switch 72. Dead failures are detected due to the relatively high-pressure gain utilized, which, when a command appears to the good servos makes the dead servo appear to be hardover in the opposite direction.
  • the four channels may have individual fluid sources and their jet'pipes may be engaged and will remain engaged with at least one fluid source through pressure responsive switching in the event its original pressure source fails.
  • a novel control system such as a fly-by-wire system" consisting of redundant channels, having fluid operated servos.
  • Such systems because of the redundancy, provide a fail operational arrangement more reliable than the conventional primary control system.
  • the arrangement includes a selfequalization arrangement for equalizing the fluid pressure on the holes cooperating with a jet pipe in each redundant channel.
  • a disengage monitoring arrangement has been included responsive to fluid pressure on a servo to disable a failed servounit.
  • a fluid type actuator having a power output section and a control section, receiving fluid under pressure, for porting fluid through suitable passages to said power section, said control section have a displaceable fluid conducting member and coacting receiving ports to vary the flow rate to the power section and thus the velocity ofdisplacement thereof in combination:
  • fluid pressure monitor means including a controller having subpassages, at least one having flow restrictive means, connected to said passages to said power section thereby responsive by said restrictive means to time duration of fluid pressures applied to said power section, operating on the member to control the rate of flow to the power section.
  • a fluid-type actuator having a power output section and a control section for porting fluid from a source of pressure fluid to said power section, said control section having a displaceable member to vary the flow rate to the power section and thus its displacement rate:
  • pressure fluid monitor means connected to said power section thus responsive to fluid pressure therein and controlling the operation of said valve.
  • valve being of the solenoid actuated type and the pressure fluid monitor means also includes a switch means having contacts controlling a circuit of said solenoid and responsive to pressure to said power means to effect opening of said valve to supply fluid to the conduit.
  • the apparatus of claim 4 in including a pressure monitoring start switch for momentarily energizing said solenoid to momentarily open the valve to passage of fluid to apply pressure to said power means and switch means.
  • each power section thereof is connected to a common force summing member, all power sections normally applying effects to an output of said summing member, whereby each feedback means is operated in accordance with the average position of the output from the summing member whereby failure to cause a first means in one section to initially displace a displaceable member in the section results in the feedback means repositioning said displaceable member in the section causing a larger than normal operating pressure thus a change in nonnal operating pressure to its power means with the accompanying operation of the pressure monitor means to terminate operation of said valve.
  • the power section includes a power piston and wherein the displaceable member controls the position of a nozzle or jet pipe which normally applies equal pressures to a 575? receiving ports or openings directly connected to opposite ends of the power piston of the power means to apply normally equal pressures thereto.
  • the apparatus of claim 7 including a pressure equalizer monitor responsive to time duration offluid pressure applied to said power section and operatively connected to said displaceable member.
  • valve being of the solenoid actuated type andthe pressure fluid through their pistons operating a force summing common member connectable for operation to said output; first means displaceable for applying differential fluid pressure to said redundant servo motor pistons to effect ,operation thereof; second means responsive to excessive differential pressures in each servomotor operating a failure switch connected to the first means for terminating application of fluid pressure to said servomotor thus terminating operation of said servomotor; and a differential pressure responsive device in each channel connected through fluid flow restrictive conducting means to opposite sides of its associated piston to respond only to time duration differential pressures across said piston and connected to the first means to modify the displacement thereof.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Supply Devices, Intensifiers, Converters, And Telemotors (AREA)
US683994A 1967-11-17 1967-11-17 Redundant force summing servo unit Expired - Lifetime US3554084A (en)

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US68399467A 1967-11-17 1967-11-17

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US (1) US3554084A (enrdf_load_stackoverflow)
DE (1) DE1809344A1 (enrdf_load_stackoverflow)
FR (1) FR1593218A (enrdf_load_stackoverflow)
GB (1) GB1249658A (enrdf_load_stackoverflow)
NL (1) NL6816366A (enrdf_load_stackoverflow)
SE (1) SE341692B (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3662550A (en) * 1971-01-11 1972-05-16 Sundstrand Corp Actuator system
US3679156A (en) * 1970-07-20 1972-07-25 Ltv Electrosystems Inc Fly-by-wire
US3727520A (en) * 1970-11-06 1973-04-17 Sperry Rand Corp Digital electrohydraulic servo system
US3826174A (en) * 1971-03-03 1974-07-30 Bendix Corp Quadruple redundant closed loop electro-hydraulic servo system
US4155288A (en) * 1976-07-10 1979-05-22 Lucas Industries Limited Control system for a fluid pressure operated actuator arrangement
US4338965A (en) * 1980-06-02 1982-07-13 Moog Inc. Self-monitoring dual-spool servovalve
US5740988A (en) * 1995-04-13 1998-04-21 General Electric Company Axisymmetric vectoring nozzle actuating system having multiple power control circuits
US6142416A (en) * 1994-09-29 2000-11-07 General Electric Company Hydraulic failsafe system and method for an axisymmetric vectoring nozzle
US6563281B1 (en) * 1999-01-19 2003-05-13 Abb Ab Device for controlling the operation of driving apparatus
RU2329411C2 (ru) * 2006-03-03 2008-07-20 Открытое акционерное общество "Ракетно-космическая корпорация "Энергия" имени С.П. Королева" Гидроцилиндр рулевой машины

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2158124B1 (enrdf_load_stackoverflow) * 1971-11-04 1974-10-31 Gen Electric

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2947286A (en) * 1958-01-29 1960-08-02 Bell Aerospace Corp Integrated actuator
US3171329A (en) * 1963-05-06 1965-03-02 Honeywell Regulator Co Control apparatus
US3190185A (en) * 1961-07-11 1965-06-22 Honeywell Inc Servomotor with monitor
US3270623A (en) * 1964-04-13 1966-09-06 Moog Inc Fluid powered servomechanism of a redundant, monitor type
US3272062A (en) * 1965-10-07 1966-09-13 Ltv Electrosystems Inc Servo valve synchronizer

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2947286A (en) * 1958-01-29 1960-08-02 Bell Aerospace Corp Integrated actuator
US3190185A (en) * 1961-07-11 1965-06-22 Honeywell Inc Servomotor with monitor
US3171329A (en) * 1963-05-06 1965-03-02 Honeywell Regulator Co Control apparatus
US3270623A (en) * 1964-04-13 1966-09-06 Moog Inc Fluid powered servomechanism of a redundant, monitor type
US3272062A (en) * 1965-10-07 1966-09-13 Ltv Electrosystems Inc Servo valve synchronizer

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3679156A (en) * 1970-07-20 1972-07-25 Ltv Electrosystems Inc Fly-by-wire
US3727520A (en) * 1970-11-06 1973-04-17 Sperry Rand Corp Digital electrohydraulic servo system
US3662550A (en) * 1971-01-11 1972-05-16 Sundstrand Corp Actuator system
US3826174A (en) * 1971-03-03 1974-07-30 Bendix Corp Quadruple redundant closed loop electro-hydraulic servo system
US4155288A (en) * 1976-07-10 1979-05-22 Lucas Industries Limited Control system for a fluid pressure operated actuator arrangement
US4338965A (en) * 1980-06-02 1982-07-13 Moog Inc. Self-monitoring dual-spool servovalve
US6142416A (en) * 1994-09-29 2000-11-07 General Electric Company Hydraulic failsafe system and method for an axisymmetric vectoring nozzle
US5740988A (en) * 1995-04-13 1998-04-21 General Electric Company Axisymmetric vectoring nozzle actuating system having multiple power control circuits
US6563281B1 (en) * 1999-01-19 2003-05-13 Abb Ab Device for controlling the operation of driving apparatus
RU2329411C2 (ru) * 2006-03-03 2008-07-20 Открытое акционерное общество "Ракетно-космическая корпорация "Энергия" имени С.П. Королева" Гидроцилиндр рулевой машины

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SE341692B (enrdf_load_stackoverflow) 1972-01-10
NL6816366A (enrdf_load_stackoverflow) 1969-05-20
GB1249658A (en) 1971-10-13
DE1809344A1 (de) 1969-07-10
FR1593218A (enrdf_load_stackoverflow) 1970-05-25

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