Patent Publication Number: US-9841039-B2

Title: Multivariable actuator pressure control

Description:
FIELD 
     The present disclosure relates to gas turbine engine actuators, and, more specifically, to a system and method that compensates for changes in operating conditions of a multivariable system. 
     BACKGROUND 
     A gas turbine actuator control system can include a control system, a gas turbine engine having a plurality of engine actuators, a hydraulic (or fueldraulic) system, and a plurality of engine sensors. Generally, a fueldraulic system maintains a predetermined pressure available for actuator control. Typically, as the pressure increases in a fueldraulic system, the losses in the fueldraulic system increase. This drives a fuel temperature increase, which can lead to decreased mission capability for the gas turbine engine. 
     SUMMARY 
     A variable pressure actuator control system for a gas turbine engine may comprise a controller, a pressure regulating electro-hydraulic servo valve assembly (P-EHSV), including a flow path, in electronic communication with the controller, a position regulating electro-hydraulic servo valve assembly (X-EHSV), including a network of flow paths, in electronic communication with the controller, a bypass regulator (BPR) in fluid communication with at least one of a pump, the P-EHSV, or the X-EHSV, the BPR configured to be controlled by the P-EHSV via a bypass pressure to vary an available pressure, and an actuator comprising an actuator piston. 
     In various embodiments, the network of flow paths may comprise a second flow path, a third flow path, a fourth flow path, and a fifth flow path, wherein an extend pressure exists between the second flow path and the third flow path and a retract pressure exists between the fourth flow path and the fifth flow path. At least one of the retract pressure and the extend pressure may be controlled by the X-EHSV. The X-EHSV may be configured to control the network of flow paths. The actuator piston may be configured to extend in response to an increase in extend pressure and retract in response to an increase in retract pressure. The available pressure may be configured to remain minimal in response to a minimal requested available pressure. The available pressure may be configured to increase in response to at least one of an increase in requested pressure or a feedback signal having reached a limit. The variable pressure actuator control system may use hydraulic fluid. 
     A gas turbine engine may comprise a variable pressure actuator control system. The variable pressure actuator control system may comprise a controller, a pressure regulating electro-hydraulic servo valve assembly (P-EHSV), including a flow path, in electronic communication with the controller, a position regulating electro-hydraulic servo valve assembly (X-EHSV), including a network of flow paths, in electronic communication with the controller, a bypass regulator (BPR) in fluid communication with at least one of a pump, the P-EHSV, or the X-EHSV, the BPR configured to be controlled by the P-EHSV via a bypass pressure to vary an available pressure, and an actuator comprising an actuator piston. 
     In various embodiments, the network of flow paths may comprise a second flow path, a third flow path, a fourth flow path, and a fifth flow path, wherein an extend pressure exists between the second flow path and the third flow path and a retract pressure exists between the fourth flow path and the fifth flow path. At least one of the retract pressure and the extend pressure may be controlled by the X-EHSV. The X-EHSV may be configured to control the network of flow paths. The actuator piston may be configured to extend in response to an increase in extend pressure and retract in response to an increase in retract pressure. The available pressure may be configured to remain minimal in response to a minimal requested available pressure. The available pressure may be configured to increase in response to a feeback signal having reached a limit. The variable pressure actuator control system may use hydraulic fluid. 
     A method of controlling a variable pressure actuator control system for a gas turbine engine may comprise: receiving, by a controller, at least one of a goal signal, a limit signal, and a sensor output signal, calculating, by the controller, at least one of a pressure signal and a position signal, sending, by the controller, at least one of the pressure signal and the position signal, receiving, by a pressure regulating electro-hydraulic servo valve assembly (P-EHSV), the pressure signal, receiving, by a position regulating electro-hydraulic servo valve assembly (X-EHSV), the position signal, and increasing, by the controller, an available pressure. 
     In various embodiments, the increasing may be in response to a feedback signal having reached a limit. In various embodiments, the method may further comprise decreasing, by the controller, the available pressure. In various embodiments, the decreasing may be in response to a decrease in desired pressure at an actuator piston. 
     The forgoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated herein otherwise. These features and elements as well as the operation of the disclosed embodiments will become more apparent in light of the following description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the figures, wherein like numerals denote like elements. 
         FIG. 1  illustrates a schematic view of a variable pressure actuator control system, in accordance with various embodiments; 
         FIG. 2  illustrates a schematic view of a control system, in accordance with various embodiments; 
         FIG. 3  illustrates a schematic view of an actuator pressure control system, in accordance with various embodiments; 
         FIG. 4  illustrates a schematic view of a variable pressure control system, in accordance with various embodiments; 
         FIG. 5  illustrates a method of controlling a variable pressure actuator control system, in accordance with various embodiments; and 
         FIG. 6  illustrates a method of controlling a variable pressure actuator control system, in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the inventions, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this invention and the teachings herein. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. The scope of the invention is defined by the appended claims. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials. In some cases, reference coordinates may be specific to each figure. 
     In various embodiments, the variable pressure control system as disclosed herein includes a hydraulic system which is capable of varying available system pressure in response to a high level control request. Variable available system pressure may reduce system temperatures, resulting in higher engine operating efficiencies. According to the present disclosure, a pressure regulating electro-hydraulic servo valve assembly (P-EHSV) may control available pressure in a hydraulic system. A position regulating electro-hydraulic servo valve assembly (X-EHSV) may control the position of an actuator piston by controlling retract pressures and extend pressures in the system. An actuator may retract in response to an increase in a retract pressure and may extend in response to an increase in an extend pressure. Thus, a retract pressure and an extend pressure may be the pressure which the actuator experiences via a supplied fluid. A constrained model based controller may determine appropriate available pressure, while tending to minimize available pressure, to achieve various benefits. 
     The term “effector signal” is used herein to describe a command signal that controls operation of the engine through the engine actuators. The effector signals can be generated by processing goals and/or limits using a control algorithm such that at least some of the goals are satisfied, subject to each limit being held (i.e., no limit is violated). An example of a goal is to move an actuator at a predetermined rate to a predetermined position. An example of a limit (i.e., a maximum or minimum) is to prevent the hydraulic pressure applied at an actuator piston from exceeding a certain value. A limit is “active” when its limit value has been met; e.g., when a temperature of a component is, or is predicted to be, at or above a maximum limit temperature. 
     System program instructions and/or controller instructions may be loaded onto a non-transitory, tangible computer-readable medium having instructions stored thereon that, in response to execution by a controller, cause the controller to perform various operations. The term “non-transitory” is to be understood to remove only propagating transitory signals per se from the claim scope and does not relinquish rights to all standard computer-readable media that are not only propagating transitory signals per se. Stated another way, the meaning of the term “non-transitory computer-readable medium” and “non-transitory computer-readable storage medium” should be construed to exclude only those types of transitory computer-readable media which were found in  In Re Nuijten  to fall outside the scope of patentable subject matter under 35 U.S.C. §101. 
     In various embodiments, an electro-hydraulic servo valve (EHSV) as used herein may comprise a directional control valve, wherein the EHSV consists of a spool, or the like, inside of a cylinder which is electronically controlled. For example, an EHSV may receive actuation commands to open, partially open, partially close and/or close various flow paths. The movement of the spool restricts or permits the flow of a hydraulic fluid. As described herein a position regulating electro-hydraulic servo valve (X-EHSV) may comprise one or more inputs and four outputs, in accordance with various embodiments. In various embodiments, each output may comprise a port, orifice, valve, or the like, referred to herein as a flow path, which may comprise a variable restriction flow path. Similarly, a pressure regulating electro-hydraulic servo valve (P-EHSV) is provided, in accordance with various embodiments. The P-EHSV may comprise one or more inputs and one or more outputs, in accordance with various embodiments. In this light, an EHSV may comprise a valve assembly. 
     Referring to  FIG. 1 , a variable pressure actuator control system  100  is schematically illustrated, in accordance with various embodiments. Variable pressure actuator control system  100  may include a high level controller  112  (e. g., a vehicle management system), a control system  114 , a gas turbine engine  116  having a plurality of actuators  118 , and a plurality of engine sensors  120 . In various embodiments, control system  114  may be referred to herein as a controller. The control system  114  is wired or wirelessly in communication with to the high level controller  112 , the gas turbine engine  116  via the engine actuators  118 , and the engine sensors  120 . The engine sensors  120  are disposed with the gas turbine engine  116 . 
     The control system  114  inputs one or more control signals  122  from the high level controller  112  and one or more sensor output signals  124  from the engine sensors  120 . The control signals  122  can include one or more goals  126  (also referred to as “command signals”) and one or more limits  128 . A signal indicative of a command to move an actuator at a predetermined rate to a predetermined position, as indicated above, is an example of a goal. A signal indicative of a control limit (i.e., a maximum or minimum) to prevent a hydraulic pressure applied at an actuator piston from exceeding a certain pressure, as indicated above, is an example of a limit. 
     Although described herein as comprising separate controllers, in various embodiments, control system  114  and high level controller  112  may comprise a single controller. For example, control system  114  may refer to system program instructions and/or controller instructions which may be loaded onto a non-transitory, tangible computer-readable medium and high level controller  112  may refer to system program instructions and/or controller instructions which may be loaded onto the same non-transitory, tangible computer-readable medium. Thus, control system  114  and high level controller  112  comprising a single controller. 
     The control system  114  provides one or more effector signals  130 ,  131  to one or more of the engine actuators  118 . The term “effector signal” is used herein, as indicated above, to refer to a command signal that controls operation of an engine actuator. Effector signal  130  and effector signal  131  are generated, as a function of the control and sensor output signals  122  and  124 , to control operation of the engine  116  by controlling the engine actuators  118 . Although illustrated in  FIG. 1  as two separate signals, effector signal  130  and effector signal  131  may comprise a single signal, in accordance with various embodiments. 
     The engine sensors  120  monitor certain engine parameters such as temperature, pressure, actuator position, etc. The engine sensors  120  output measured parameter data  132  to the control system  114 , via the sensor output signals  124  (i.e., feedback signals), indicative of the monitored engine parameters. A signal indicative of temperature, pressure, or actuator position that is measured by an engine sensor is an example of a sensor output signal. 
     With respect to  FIG. 2  and  FIG. 3 , elements with like element numbering as depicted in  FIG. 1  are intended to be the same and will not necessarily be repeated for the sake of clarity. 
     With reference to  FIG. 2 , the control system  114  may include a control signal interface  234 , an effector signal generator  236 , an actuation system modeling device  238 , a prediction signal biasing device  240 , a memory storage device  242 , a comparator  244 , and/or a bias estimator  246 . The effector signal generator  236  may include a dynamic inversion module  248  and/or an optimization module  250 . 
     Although described herein as being implemented on control system  114 , it is contemplated that control signal interface  234 , effector signal generator  236 , actuation system modeling device  238 , prediction signal biasing device  240 , memory storage device  242 , comparator  244 , and bias estimator  246  may be implemented on one or more controllers and in any combination thereof. 
     The control signal interface  234  receives the control signals  122  (i.e., the goals  126  and limits  128 ) from the high level controller  112  (see  FIG. 1 ), and stored parameter data  252  from the memory storage device  242 . The control signal interface  234  provides reference value data  254  to the dynamic inversion module  248 . The dynamic inversion module  248  receives bias estimates  256  from the bias estimator  246  and model term data  258  from the actuation system modeling device  238 . The dynamic inversion module  248  provides effector equation data  260  to the optimization module  250 . The optimization module  250  provides one or more effector signals  130 ,  131  to one or more of the engine actuators  118  (see  FIG. 1 ), and the actuation system modeling device  238 . The actuation system modeling device  238  provides predicted parameter data  262  to the prediction signal biasing device  240 . The prediction signal biasing device  240  receives the bias estimates  256  from the bias estimator  246 , and provides biased predicted parameter data  264  to the memory storage device  242 . The predicted parameter data  264  includes predictions of the values of states and variables that have associated goals or limits at the next control process cycle. The comparator  244  receives the stored parameter data  252  from the memory storage device  242 , and the measured parameter data  132  from one or more of the engine sensors  120  (see  FIG. 1 ). The stored parameter data  252  includes estimates of the current values of states and variables that have associated goals or limits the comparator  244  provides prediction error data  266  to the bias estimator  246 , which processes this data to produce bias estimates  256 . The bias estimates correct for model error. The bias estimates include at least one bias which, when added to at least one predicted parameter data  262 , corrects the output for model error. 
     The control signal interface  234  is configured to generate the reference value data  254  by processing the goals  126 , the limits  128  and the stored parameter data  252  using a reference model. The reference model is operable to reflect a desired future dynamic response to possibly changing goals and limits. The reference value data  254  is indicative of a desired value of one or more goals and one or more limits, which are determined for a subsequent (e.g., the next) control process cycle (also referred to as a “program cycle” or “update”). A numerical value indicative of a hydraulic pressure that corresponds to an actuator position is an example of a goal value. In various embodiments, each goal can also be associated with one or more additional signals such as 1) a reference value of hydraulic pressure included in the reference value data  254  indicative of the desired hydraulic pressure dynamic response to the goal, 2) a model prediction of actual hydraulic pressure included in the predicted parameter data  262 , 3) a sensor measurement of actual hydraulic pressure included in the measured parameter data  132 , and/or 4) a hydraulic pressure bias to correct for model errors. A numerical value indicative of a maximum actuator displacement rate is an example of a limit value. In various embodiments, each limit can also be associated with one or more additional signals such as: a reference value of actuator piston displacement rate included in the reference value data  254  indicative of the desired actuator displacement rate dynamic response to the possibly changing limit value, a model prediction of actual actuator displacement rates included in the predicted parameter data  262 , a sensor measurement of actual actuator displacement rates included in the measured parameter data  132 , and/or a actuator displacement rate bias to correct for model errors. 
     With reference to  FIG. 3 , an actuator pressure control system  300  is provided. An xy-axis is provided for ease of illustration. In various embodiments, an actuator pressure control system  300  may include a pump  302 , a pressure regulating electro-hydraulic servo valve assembly (P-EHSV)  310 , a position regulating electro-hydraulic servo valve assembly (X-EHSV)  320 , a bypass regulator (BPR)  330 , and at least one actuator  350 . In various embodiments, pump  302  may be a fixed displacement pump. 
     In various embodiments, P-EHSV  310  may include flow path  332 . In various embodiments, flow path  332  may comprise a variable restriction (VR) flow path. 
     In various embodiments, X-EHSV  320  may include flow path  322 , flow path  324 , flow path  326 , and/or flow path  328 . In various embodiments, flow path  322 , flow path  324 , flow path  326 , and/or flow path  328  may comprise a variable restriction (VR) flow path. Flow path  322  may be referred to herein as a second flow path. Flow path  324  may be referred to herein as a third flow path. Flow path  326  may be referred to herein as a fourth flow path. Flow path  328  may be referred to herein as a fifth flow path. Flow path  322 , flow path  324 , flow path  326 , and flow path  328  may be collectively referred to herein as a network of flow paths. 
     In various embodiments, BPR  330  may include flow path  334 . In various embodiments, flow path  334  may comprise a variable restriction (VR) flow path. Flow path  334  may be referred to herein as a sixth flow path. 
     In various embodiments, pump  302  may be in fluid communication with BPR  330 . In various embodiments, pump  302  may be in fluid communication with BPR  330  via fixed restriction  309 . In various embodiments, pump  302  may be in fluid communication with BPR  330  via conduit  362 . In various embodiments, pump  302  may be in fluid communication with X-EHSV  320 . In various embodiments, pump  302  may be in fluid communication with X-EHSV  320  via conduit  362 , for example. In various embodiments, BPR  330  may be in fluid communication with X-EHSV  320 . In various embodiments, BPR  330  may be in fluid communication with P-EHSV  310 . In various embodiments, BPR  330  may be in fluid communication with actuator piston  352  via X-EHSV  320 . 
     In various embodiments, P-EHSV  310  may be in electronic communication with control system  114  (see  FIG. 1 ). In various embodiments, P-EHSV  310  may comprise an electronics controller. In various embodiments, X-EHSV  320  may be in electronic communication with control system  114  (see  FIG. 1 ). In various embodiments, X-EHSV  320  may comprise an electronics controller. 
     In various embodiments, P-EHSV may receive effector signal  131 . Effector signal  131  may be a pressure command signal. In various embodiments, effector signal  131  may comprise a value or a current, such as a desired pressure, for example. P-EHSV  310  may be configured to one of restrict or permit hydraulic fluid to flow through flow path  332 , in response to effector signal  131 . In various embodiments, flow path  332  may receive pressurized hydraulic fluid at a regulated pressure  304 . In various embodiments, regulated pressure  304  may be maintained by an outside hydraulic system. In various embodiments, hydraulic fluid may flow through flow path  332  to drain  360  and/or to BPR  330 . A fixed restriction  307  may be located between drain  360  and flow path  332 . In various embodiments, drain  360  may comprise a tank. Flow path  332  may be configured to open in response to a command for an increase in bypass pressure  306  and close in response to a command for a decrease in bypass pressure  306 . Bypass pressure  306  may be configured to increase in response to effector signal  131  commanding more pressure to be applied at actuator piston  352 . Bypass pressure  306  may be configured to decrease in response to effector signal  131  commanding less pressure to be applied at actuator piston  352 . In various embodiments, bypass pressure  306  may be configured to control BPR  330 . For example, in various embodiments, a change in bypass pressure  306  may reduce the size of the flowpath for flow of hydraulic fluid through BPR  330 , thus increasing available pressure  312 . 
     Pump  302  may supply a constant flow of pressurized hydraulic fluid to actuator pressure control system  300 . Damping pressure  308  may exist between fixed restriction  309  and BPR  330 . Hydraulic fluid may flow from pump  302 , through flow path  334 , into drain  360 . BPR  330  may control flow path  334 . Flow path  334  may open to decrease available pressure  312 . Flow path  334  may close to increase available pressure  312 . Accordingly, BPR  330  and/or available pressure  312  may be controlled by P-EHSV  310 . 
     In various embodiments, hydraulic fluid may flow at available pressure  312  to flow path  322  and flow path  326 . Hydraulic fluid may flow through flow path  322 , through flow path  324 , and into drain  360 . Hydraulic fluid may flow through flow path  326 , through flow path  328 , and into drain  360 . Hydraulic fluid located between flow path  322  and flow path  324  may comprise extend pressure  314 . Hydraulic fluid located between flow path  326  and flow path  328  may comprise retract pressure  316 . Extend pressure  314  may be increased to extend actuator piston  352 . Retract pressure  316  may be decreased to extend actuator piston  352 . Retract pressure  316  may be increased to retract actuator piston  352 . Extend pressure  314  may be decreased to retract actuator piston  352 . 
     In various embodiments, X-EHSV  320  may receive effector signal  130 . Effector signal  130  may be a position command signal. In various embodiments, effector signal  130  may comprise a value or a current, such as an actuator position value, for example. X-EHSV  320  may be configured to one of restrict or permit hydraulic fluid to flow through flow path  322 , flow path  324 , flow path  326 , and/or flow path  328  in response to effector signal  130 . Stated another way, X-EHSV  320  may be configured to open and or close at least one of flow path  322 , flow path  324 , flow path  326 , and/or flow path  328  in response to effector signal  130 . Accordingly, actuator piston  352  may be configured to at least one of extend (in the positive x-direction) or retract (in the negative x-direction) in response to effector signal  130 . Accordingly, extend pressure  314  and/or retract pressure  316  may be controlled by X-EHSV  320 . 
     In various embodiments, extend pressure  314  and retract pressure  316  may be limited by available pressure  312 . For example, a limit may be reached by extend pressure  314  and thus X-EHSV  320  when extend pressure  314  has reached available pressure  312 . For example, extend pressure  314  may be equal to available pressure  312  when flow path  324  is in a closed position and flow path  322  is in an open position. Thus, the pressure of hydraulic fluid supplied to actuator  350  may be limited by available pressure  312 . 
     In various embodiments, available pressure  312  may be configured to increase in response to a feedback signal having reached a limit. Stated another way, available pressure  312  may be configured to increase in response to control system  114  (see  FIG. 2 ) having reached a limit. A feedback signal may include the value of an operating condition of actuator pressure control system  300 . In various embodiments, a feedback signal may include a rate of change of the position of actuator piston  352 . A feedback signal may include an error in the rate of change of the position of actuator piston  352 . A feedback signal may include an error of the position of actuator piston  352 . A feedback signal may include a rate of change of extend pressure  314  and/or retract pressure  316 . A feedback signal may include an error in the rate of change of extend pressure  314  and/or retract pressure  316 . A feedback signal may include an error in extend pressure  314  and/or retract pressure  316 . A feedback signal may include available pressure  312 . In various embodiments, a feedback signal may be supplied to a controller, such as control system  114  (see  FIG. 2 ) for example, via a sensor or the like. Accordingly, actuator pressure control system  300  may include one or more sensors. 
     Accordingly, available pressure  312  may be configured to remain minimal when minimal available pressure  312  is desired by actuator pressure control system  300 . Accordingly, available pressure  312  may be configured to decrease in response to a decrease in desired pressure applied to actuator piston  352 . Minimizing available pressure  312  may result in lower operating temperatures and better engine mission capability. 
     In various embodiments, load force  354  may be a force acting on actuator piston  352 . Load force  354  may be, for example, a force transmitted through an engine nozzle in response to exhaust pressure in the nozzle. In various embodiments, extend pressure  314  and retract pressure  316  may be configured to prevent actuator piston  352  from moving in response to load force  354 . In various embodiments, extend pressure  314  and retract pressure  316  may be configured to extend or retract actuator piston  352 , thus opening or closing an engine nozzle, for example. In various embodiments, the pressure applied to actuator piston  352  may be determined using load force  354 . 
     Hydraulic fluid in actuator pressure control system  300  may comprise fuel, or any other suitable fluid. Sensors may be used in actuator pressure control system  300  to detect parameters such as pressure, temperature, and position. 
     In various embodiments,  FIG. 4  illustrates a variable pressure control system  400 . In various embodiments, variable pressure control system  400  may be similar to variable pressure actuator control system  100 . In various embodiments, variable pressure control system  400  may comprise model based controller (MBC)  402 , a hydraulic pressure system  410 , and a plurality of actuators such as actuator  412  and actuator  414 , for example. MBC  402  may comprise an on-board model  422  and actuation controller  424 . 
     In various embodiments, on-board model  422  may receive a plurality of signals  430 . Plurality of signals  430  may include signals such as pre-predicted model requests, position requests, actuator positions, and feedback signals, for example. 
     In various embodiments, actuation controller  424  may receive a plurality of signals including pressure request  428  and plurality of position requests  426 , for example. In various embodiments, actuation controller  424  may determine or calculate a plurality of effector signals such as pressure signal  432  and plurality of position signals  434 , for example. In various embodiments, actuation controller  424  may comprise a single loop system. 
     In various embodiments, plurality of position requests  426  may be used to determine pressure signal  432 . For example, if an increase in available pressure is desired to reach a predetermined position, the value of pressure signal  432  may be varied according to the desired pressure. Plurality of position signals  434  may be calculated based on plurality of position requests  426 . Plurality of position signals  434  may be calculated based on various parameters such as load forces, available pressure, rate of change limits, etc. In various embodiments, plurality of position signals  434  may control the position of actuator  412  and/or actuator  414 . Thus, actuator  412  and/or actuator  414  may be in electronic communication with MBC  402 . 
     In various embodiments, pressure signal  432  may be received by hydraulic pressure system  410 . Thus, hydraulic pressure system  410  may be in electronic communication with MBC  402 . In various embodiments, hydraulic pressure system  410  may supply hydraulic pressure to a plurality of actuators such as actuator  412  and actuator  414 , for example. Accordingly, hydraulic pressure system  410  may be in fluid communication with the plurality of actuators. In various embodiments, hydraulic pressure system  410  may be similar to actuator pressure control system  300 , as described herein. 
     With reference to  FIG. 5 , a method  500  for controlling a variable pressure actuator control system is provided. Method  500  may comprise receiving, by a controller, at least one of a goal signal, a limit signal, and a sensor output signal (see step  501 ). Method  500  may comprise calculating, by the controller, at least one of a pressure signal and a position signal (see step  502 ). Method  500  may comprise sending, by the controller, at least one of the pressure signal and the position signal (see step  503 ). The pressure signal may be sent to a pressure regulating electro-hydraulic servo valve assembly (P-EHSV). The position signal may be sent to a position regulating electro-hydraulic servo valve assembly (X-EHSV). Method  500  may comprise receiving, by a pressure regulating electro-hydraulic servo valve assembly (P-EHSV), the pressure signal (see step  504 ). The pressure signal may be received from the controller. Method  500  may comprise receiving, by a position regulating electro-hydraulic servo valve assembly (X-EHSV), the position signal (see step  505 ). The position signal may be received from the controller. Method  500  may comprise decreasing, by the controller, an available pressure (see step  506 ). 
     With respect to  FIG. 6 , elements with like element numbering as depicted in  FIG. 5 , are intended to be the same and will not be repeated for the sake of clarity. Method  600  as illustrated in  FIG. 6  may be similar to method  500  as illustrated in  FIG. 5 . In various embodiments, method  600  may comprise increasing, by the variable pressure actuator control system, an available pressure (see step  606 ). 
     With reference now to  FIG. 1  and  FIG. 5 , step  501  may include receiving, by control system  114 , at least one of goals  126 , limits  128 , and sensor output signals  124 . Step  502  may include calculating, by control system  114 , at least one of effector signal  130  and effector signal  131 . Step  503  may include sending, by control system  114 , at least one of effector signal  130  and effector signal  131 . Effector signal  131  may be sent to pressure regulating electro-hydraulic servo valve assembly (P-EHSV)  182 . Effector signal  130  may be sent to a position regulating electro-hydraulic servo valve assembly (X-EHSV)  184 . Effector signal  130  and effector signal  131  may be sent to one or more of engine actuators  118  via at least one of P-EHSV  182  and X-EHSV  184 . Step  504  may include receiving, by P-EHSV  182 , effector signal  131 . Effector signal  131  may be received from control system  114 . Step  505  may include receiving, by X-EHSV  184 , effector signal  130 . Effector signal  130  may be received from control system  114 . Step  506  may include decreasing, by control system  114 , available pressure  312  (see  FIG. 3 ). With reference now to  FIG. 1  and  FIG. 6 , step  606  may include increasing, by control system  114 , available pressure  312  (see  FIG. 3 ). 
     Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the inventions. The scope of the inventions is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. 
     Systems, methods and apparatus are provided herein. In the detailed description herein, references to “various embodiments”, “one embodiment”, “an embodiment”, “an example embodiment”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. 
     Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f), unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.