Dual independent hybrid actuator system

Abstract

To enable independent control of a machine component such as a flight control surface by hydraulic force by a hydraulic system and mechanical force by an electric motor.SOLUTION: A double independent type hybrid type actuator system 100 includes an actuator body 110 defining a hydraulic chamber. The actuator system 100 is disposed in the hydraulic chamber, and includes a hydraulic piston assembly 118 that includes a hydraulic piston 120 dividing the hydraulic chamber into a first hydraulic sub chamber 112A in fluid communication with a first hydraulic fluid passage 114 and a second hydraulic sub chamber 112B in fluid communication with the second hydraulic fluid passage 116. The actuator system 100 further includes an electric motor 140 attached to the actuator body 110, and a screw wheel 150 mechanically united to a motor shaft 142 of the electric motor 140. The screw wheel 150 is engaged with a screw port 152 formed in the hydraulic piston assembly 118.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The invention of this disclosure relates generally to an actuator that is independently operable by a hydraulic system and an electric motor. [Background technology]

[0002] Aircraft utilize flight control surfaces, such as flaps and rudders, that are operated by actuators to change the orientation and / or position of the flight control surfaces relative to the airframe. Hydraulic actuators, commonly used on commercial aircraft, are controlled by electrohydraulic servo valves in the hydraulic system that communicate with the hydraulic actuators. Other types of mechanical systems outside of aircraft also utilize hydraulic actuators to operate mechanical components. In some cases, backup systems may be used in conjunction with hydraulic actuators to allow the backup system to operate flight control surfaces or other mechanical components if the hydraulic system cannot provide sufficient control. Summary of the Invention [Means for solving the problem]

[0003] According to one example of the present disclosure, a dual independent hybrid actuator system includes an actuator body defining a hydraulic chamber within the actuator body. The actuator body further defines a first hydraulic fluid passage and a second hydraulic fluid passage in fluid communication with the hydraulic chamber. The actuator system includes a hydraulic piston assembly including a hydraulic piston disposed within the hydraulic chamber and dividing the hydraulic chamber into a first hydraulic subchamber in fluid communication with the first hydraulic fluid passage and a second hydraulic subchamber in fluid communication with the second hydraulic fluid passage. The actuator system further includes a piston rod attached to the hydraulic piston passing through the second hydraulic subchamber with a distal end protruding outwardly from the actuator body. The actuator system further includes an electric motor attached to the actuator body and a threaded axle mechanically coupled to a motor shaft of the electric motor. The threaded axle passes through the first hydraulic subchamber and engages a threaded port formed in the hydraulic piston assembly.

[0004] According to another example of the present disclosure, a method of controlling a dual independent hybrid actuator system includes controlling operation of an electrohydraulic servo valve of a hydraulic system to generate a first hydraulic pressure differential between opposite sides of a hydraulic piston to move a piston rod attached to the hydraulic piston in a first translational direction. The method further includes controlling operation of an electric motor having a motor shaft mechanically coupled to the hydraulic piston via a threaded axle during movement of the piston rod in the first translational direction. Controlling operation of the electric motor includes providing power to the electric motor to rotate the motor shaft in a first rotational direction, thereby moving the piston rod in the first translational direction in cooperation with a force provided by the first hydraulic pressure differential or reducing resistance by the motor to movement of the piston rod in the first translational direction.

[0005] According to another example of the present disclosure, a method of controlling a dual independent hybrid actuator system includes controlling operation of an electro-hydraulic servo valve of a hydraulic system to generate a first hydraulic pressure differential between opposite sides of a hydraulic piston to move a piston rod attached to the hydraulic piston in a first translational direction during a first control action; and controlling operation of an electric motor having a motor shaft mechanically coupled to the hydraulic piston via a threaded axle to rotate the motor shaft in a first rotational direction and move the piston rod in the first translational direction during a second control action.

[0006] The aspects and techniques discussed in this summary can be provided independently in various examples or can be combined in yet other examples, further details of which are described in the following description and with reference to the drawings. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 illustrates an example of a dual independent hybrid actuator system according to the present disclosure. [Figure 2A] FIG. 2 illustrates an example electric brake that can be used with the actuator system of FIG. 1. [Figure 2B] FIG. 2 is another diagram illustrating an example electric brake that can be used with the actuator system of FIG. 1. [Figure 3A] 2 is a detailed view of the actuator system of FIG. 1, including an exemplary interface between a screw axle and a screw port. [Figure 3B] FIG. 2 is a detailed view of the actuator system of FIG. 1, including an exemplary in-line check valve. [Figure 4] 2 is a flow chart illustrating an example method for controlling a dual independent hybrid actuator system, including the actuator system of FIG. 1. [Diagram 5] FIG. 2 is a schematic diagram of an example control architecture for a dual independent hybrid actuator system, including the actuator system of FIG. 1. [Figure 6] FIG. 2 illustrates an example of a planetary gear system that may be included in the drive train of the actuator system of FIG. 1. [Figure 7] FIG. 6 illustrates an exemplary computing system capable of implementing the method of FIG. 4 and incorporating the control architecture of FIG. 5 for a dual independent hybrid actuator system, including the actuator system of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Disclosed herein is a dual independent hybrid actuator system and method of operation that allows for independent control of a mechanical component, such as a flight control surface, by hydraulic force provided by a hydraulic system and mechanical force provided by an electric motor. In a disclosed example, the actuator system incorporates an electric motor into the actuator body and mechanically couples the electric motor to a hydraulic piston assembly via a threaded axle. The hydraulic piston assembly may be independently operated by the electric motor via the threaded axle and / or by the hydraulic system providing a hydraulic pressure differential on either side of the hydraulic piston. In one example, an electrohydraulic servo valve (also referred to as an electrohydraulic servo actuator (EHSA)) of the hydraulic system may be used for primary control of the actuator position, and an electric motor mechanically coupled to the hydraulic piston assembly may be used for alternative or additional control of the actuator position.

[0009] Figure 1 illustrates an example of a dual independent hybrid actuator system 100. The actuator system 100 includes an actuator body 110 that defines a hydraulic chamber 112 within the actuator body. In Figure 1, an embodiment of the actuator system 100 is shown in cross section to depict the internal components contained within the actuator body 110. The actuator body 110 further defines a first hydraulic fluid passageway 114 and a second hydraulic fluid passageway 116 that are in fluid communication with different regions of the hydraulic chamber 112.

[0010] The actuator system 100 further includes a hydraulic piston assembly 118 including a hydraulic piston 120 disposed within the hydraulic chamber 112. The hydraulic piston 120 divides the hydraulic chamber 112 into a first hydraulic sub-chamber 112A in fluid communication with the first hydraulic fluid passage 114 and a second hydraulic sub-chamber 112B in fluid communication with the second hydraulic fluid passage 116. The hydraulic piston 120 may include one or more seals and / or bearings, shown generally at 121 and 123, to interface with an interior surface of the hydraulic chamber 112 to seal the first hydraulic sub-chamber 112A from the second hydraulic sub-chamber 112B and / or to reduce friction opposing movement of the hydraulic piston relative to the actuator body.

[0011] The hydraulic piston assembly 118 further includes a piston rod 122 attached to the hydraulic piston 120. The piston rod 122 passes through an opening 111 formed in the actuator body 110 into the second hydraulic sub-chamber 112B and has a distal end 124 that projects outwardly from the actuator body. The actuator body 110 may include one or more seals and / or bearings, shown diagrammatically at 113, to interface with the piston rod 122 to seal the second hydraulic sub-chamber 112B and / or reduce friction opposing movement of the piston rod.

[0012] The actuator body 110 in combination with the piston rod 122 forms a linkage 126 that includes a first bearing attachment point 128 at a distal end 124 of the piston rod 122 and a second bearing attachment point 130 at another distal end 132 of the actuator body opposite the first bearing attachment point 128. As used herein, the term "actuator position" may refer to a length of the linkage 126 formed between the first bearing attachment point 128 of the piston rod 122 and the second bearing attachment point 130 of the actuator body. In one example, the first bearing attachment point 128 may be mechanically coupled to a controlled mechanical component 127 (e.g., a flight control surface), shown diagrammatically in FIG. 1. The controlled mechanical component 127 may include or be associated with a positioning sensor 129 that allows the electronic control system 170 to measure and determine a position and / or orientation of the mechanical component 127, enabling the electronic control system to move the hydraulic piston assembly 118 to achieve a target position and / or orientation of the mechanical component 127.

[0013] The actuator system 100 includes a hydraulic system 134 in communication with the first hydraulic fluid passage 114 and the second hydraulic fluid passage 116 of the actuator body 110. The hydraulic system 134 is shown diagrammatically in FIG. 1 as including one or more hydraulic pumps 136 and one or more electrohydraulic servo valves 138. The one or more hydraulic pumps 136 may be selectively actuated by an electronic control system 170 to generate hydraulic pressure within the hydraulic system 134, and the one or more servo valves 138 may be selectively actuated by the electronic control system to independently control the supply of hydraulic fluid to each of the first hydraulic subchamber 112A via the first hydraulic fluid passage 114 and the second hydraulic subchamber 112B via the second hydraulic fluid passage 116 to generate a target pressure differential between the first and second hydraulic subchambers. However, in at least some examples, one or more bidirectional hydraulic pumps (e.g., of pump 136) or hydraulic motors of hydraulic system 134 may be used to control the hydraulic pressure difference between the first hydraulic sub-chamber 112A and the second hydraulic sub-chamber 112B.

[0014] According to an example operation of the actuator system 100, a first pressure differential may be created between the first hydraulic subchamber 112A and the second hydraulic subchamber 112B, the first hydraulic subchamber having a higher hydraulic pressure than the second hydraulic subchamber, causing the hydraulic piston 120 and piston rod 122 of the hydraulic piston assembly 118 to move in a first translational direction 102 (i.e., an extension direction) along the translational axis 125, thereby increasing the length of the linkage 126 between the bearing attachment points 128 and 130. A second pressure differential between the first hydraulic subchamber 112A and the second hydraulic subchamber 112B may be generated by the hydraulic system 134, with the second hydraulic subchamber having a higher hydraulic pressure than the first hydraulic subchamber, causing the hydraulic piston 120 and piston rod 122 of the hydraulic piston assembly 118 to move along the translation axis 125 in a second translation direction 104 opposite the first translation direction 102 (i.e., the backward direction), thereby decreasing the length of the linkage 126 between the attachment points 128 and 130.

[0015] The actuator system 100 further includes an electric motor 140 attached to the actuator body 110. In the example shown in FIG. 1, the electric motor 140 is housed in a separate subchamber of the actuator body 110 defined in part by the cover portion 110A. The electric motor 140 includes a motor shaft 142 that rotates about an axis (e.g., 125) upon supply of power by an electronic control system 170. The electric motor 140 may take the form of a DC motor or an AC motor, depending on the implementation. The electronic control system 170 may selectively vary the power and / or phase supplied to the electric motor 140 to control the direction and rotational speed of the motor shaft 142.

[0016] The motor shaft 142 may be mounted in one or more axial bearings, examples of which are shown diagrammatically at 145A and 145B. Axial bearings may be provided in any other suitable number and / or locations on the motor shaft 142. The axial bearings 145A and 145B may take the form of thrust bearings that support the load of the motor shaft in the axial or lateral directions (e.g., along axis 125).

[0017] The actuator system 100 further includes a threaded axle 150 mechanically coupled to the motor shaft 142 of the electric motor 140. In the example shown in Figure 1, the threaded axle 150 passes through the first hydraulic subchamber 112A and engages with a threaded port 152 formed in the hydraulic piston assembly 118. As an example, the hydraulic piston assembly 118 includes a ball screw nut (shown at 310 in Figure 3A) that defines the threaded port 152, and the threaded axle 150 forms a ball screw shaft (shown at 312 in Figure 3A).

[0018] In at least some examples, the hydraulic piston assembly 118 defines an internal chamber 154 within the hydraulic piston 120 and / or piston rod 122 that accommodates a portion of the threaded axle 150 that protrudes through the threaded port 152. In the example shown in FIG. 1, the threaded axle 150 is coaxial with the piston rod 122 and the translational axis 125 of the piston rod. However, in other examples, the threaded axle 150 may be parallel to, but not coaxial with, either the piston rod 122 or the translational axis 125. Also, in the example shown in FIG. 1, the motor shaft 142 is coaxial with, but not coaxial with, the piston rod 122 and the translational axis 125 of the piston rod. However, in other examples, the motor shaft 142 may be oriented at an angle relative to the piston rod 122 and the translational axis 125, or the motor shaft 142 may be parallel to, but not coaxial with, either the piston rod 122 or the translational axis 125. For example, the motor shaft 142 may be mechanically coupled to the threaded axle 150 via a drivetrain that allows the motor shaft 142 to be offset from and / or angled relative to the threaded axle 150.

[0019] The actuator system 100 may include a drive train 160 by which the threaded axle 150 is mechanically coupled to the motor shaft 142 of the electric motor 140. In at least some examples, the drive train 160 provides a non-parity (e.g., greater than or less than 1:1) effective gear ratio between the motor shaft 142 and the threaded axle 150. As an example, the non-parity effective gear ratio of the drive train 160 reduces the rotational speed of the threaded axle 150 relative to the rotational speed of the motor shaft 142, thereby providing the motor 140 with a mechanical advantage to increase the motor torque provided to the threaded axle 150 and the piston assembly 118. In the example shown in FIG. 6, the drive train 160 includes a planetary gear system. However, other suitable drive trains may be used. FIG. 1 further illustrates the drive train 160 including an output shaft 162 and an axial bearing 164 by which the threaded axle 150 is mounted or otherwise mechanically coupled to the threaded axle 150. The axial bearing 164 may take the form of a thrust bearing that supports the load of the output shaft 162 in an axial or lateral direction (eg, along the axis 125).

[0020] In at least some examples, the electric motor 140 may take the form of a stepper motor that allows the electronic control system 170 to measure and determine the rotational position and speed of the motor shaft 142. Additionally or alternatively, one or more position sensors 148A, 148B, etc. may be included that allow the electronic control system 170 to measure and determine the rotational position and speed of the motor shaft 142. The position sensors may include resolvers attached to the motor shaft 142, the output shaft 162, and / or the threaded axle 150 to measure the rotation of the motor shaft 142 and / or the threaded axle 150. The position sensors may also include, by way of example, encoders and Hall effect sensors to determine the rotational position of the shafts. The position sensors may be used, at least in some examples, to detect backlash between the threaded axle 150 and the hydraulic piston 120. The position sensors may be provided in other suitable numbers and / or locations on the motor shaft 142, the output shaft 162, and / or the threaded axle 150. In at least some examples, the actuator position may be determined by electronic control system 170 from sensor data received from position sensors 148A and 148B, or, in the case of a stepper motor, from electric motor 140 reporting its rotational position.

[0021] According to an example operation of actuator system 100, rotation of motor shaft 142 of electric motor 140 in a first rotational direction (e.g., 144 or 146) causes hydraulic piston 120 and piston rod 122 of hydraulic piston assembly 118 to move in a first translational direction 102, causing distal end 124 of piston rod 122 to extend outwardly from actuator body 110, thereby increasing the length of linkage 126 between attachment points 128 and 130. Rotation of motor shaft 142 of electric motor 140 in a second rotational direction opposite to the first rotational direction causes hydraulic piston 120 and piston rod 122 of hydraulic piston assembly 118 to move in a second translational direction 104, opposite to the first translational direction 102, causing distal end 124 of piston rod 122 to retract inwardly toward actuator body 110, thereby decreasing the length of linkage 126 between attachment points 128 and 130.

[0022] The control system 170 can coordinate operation of the electric motor 140 with operation of one or more electrohydraulic servo valves 138 of the hydraulic system 134 during at least some operating conditions. For example, the control system 170 can increase hydraulic pressure in the first hydraulic subchamber 112A relative to the second hydraulic subchamber 112B to achieve a first pressure differential to urge the piston rod 122 in the first translational direction 102 while simultaneously rotating the electric motor 140 in a first rotational direction, thereby increasing the length of the linkage 126 between the attachment points 128 and 130 through the coordinated operation of both the hydraulic system 134 and the electric motor 140. During other operating conditions, the electronic control system 170 can increase the hydraulic pressure in the second hydraulic sub-chamber 112B relative to the first hydraulic sub-chamber 112A to achieve a second pressure differential and simultaneously actuate the electric motor 140 to rotate in a second rotational direction opposite the first rotational direction, thereby decreasing the length of the linkage 126 between the attachment points 128 and 130 through coordinated action of both the hydraulic system 134 and the electric motor 140. Additional examples of coordinated action between the hydraulic system 134 and the electric motor 140 are described in further detail with reference to Figures 4 and 5.

[0023] The possibility of backdriving the electric motor 140 and drive train 160 may exist during conditions where there is a loss of hydraulic pressure and / or control of the hydraulic system 134. Under these conditions, the electric motor 140 in combination with the screw axle 150 may be used as the primary mode of control of the hydraulic piston assembly 118. However, backdriving of the electric motor 140 may occur when a force (e.g., an aerodynamic load) is applied to the controlled mechanical component 127 that is greater than the static force resisting movement of the hydraulic piston assembly 118. In at least some examples, the electric motor 140, drive train 160, and / or screw axle 150 may be used in conjunction with one or more electric brakes 149A, 149B, etc., that may be electrically actuated by the electronic control system 170. The electric brakes 149A and 149B may be selectively engaged by the electronic control system 170 to resist or prevent movement of the hydraulic piston assembly 118 due to backdriving by the controlled mechanical component. Electric brakes may be provided in other suitable numbers and / or locations on the motor shaft 142, the output shaft 162, and / or the screw axle 150.

[0024] 2A and 2B show an example electric brake 200 that can be used with actuator system 100 of FIG. 1, such as for electric brakes 149A and 149B. Electric brake 200 includes a housing 210 that can be attached to actuator body 110 of actuator system 100; a coil 212 to which electrical energy is applied; a drive cup 214 attached to a shaft to which braking is provided, such as motor shaft 142; a support plate 216; an armature 218; an end plate 220; a set of friction discs 222 attached between armature 218 and end plate 220; and a spring 224 attached between armature 218 and support plate 216. In one example, electric brake 200 is an electrically released brake that is engaged when electrical energy is not present in coil 212. When electrical energy is not provided to the coil 212, the spring 224 exerts a force on the set of friction disks 222 as shown in FIG. 2B, thereby exerting a braking force on the rotation of the shaft and preventing torque on the shaft. In at least some examples, the brake is not released until electricity is provided to the coil. Under that condition, the coil generates a magnetic field that is used to pull the armature plate toward or against the spring, overcoming the spring force and allowing the friction disks to separate from each other. This allows the disks to rotate freely without the ability to transmit or hold torque. FIG. 2A illustrates an example in which electrical energy is provided to the coil 212, attracting the armature 218 (e.g., comprising a magnet or a magnetically attractive material such as a metal) to the support plate 216, removing the braking force applied to the shaft. It will be understood that the electric brake 200 is one example of an electric brake that can be used with the actuator system 100, and that other electric brakes can be used, including electric brakes that exert a braking force on the shaft upon the supply of electrical energy to the brake.

[0025] 3A shows a detailed view of the actuator system 100 of FIG. 1, including an exemplary interface between the threaded axle 150 and the threaded port 152. In one example, the threaded port 152 is formed by a ball screw nut 310, and the threaded axle 150 forms a ball screw shaft 312. In this example, the ball screw nut 310 defines an outer threaded race 314, and the ball screw shaft 312 defines an inner threaded race 316. The threaded races 314 and 316 collectively include ball bearings 318 that reduce rotational friction and support radial and axial loads between the ball screw nut 310 and the ball screw shaft 312.

[0026] 3A, the hydraulic piston assembly 118 defines a fluid pathway 320 between the internal chamber 154 and the first hydraulic sub-chamber 112A that is independent of the opening 322 of the threaded port 152 through which the threaded axle 150 passes. The fluid pathway 320 forms a drain port that allows drainage of hydraulic fluid that leaks past the ball bearing 318 and into the internal chamber 154. If the hydraulic fluid is unable to drain from the internal chamber 154, damage to the piston rod 122 and / or the hydraulic piston assembly 118 may occur. Thus, the fluid pathway 320 may reduce or prevent damage caused by a buildup of hydraulic fluid in the internal chamber 154.

[0027] In FIG. 3A, the fluid path 320 is formed in the ball screw nut 310, however, the fluid path may alternatively or additionally be formed in the body of the hydraulic piston 120 and / or the piston rod 122. The hydraulic piston assembly 118 further includes a one-way in-line check valve 324 disposed along the fluid path 320, thereby providing greater resistance to hydraulic fluid flowing along the fluid path through the in-line check valve toward the inner chamber 154 compared to hydraulic fluid flowing from the inner chamber toward the first hydraulic sub-chamber 112A through the in-line check valve. Thus, when the threaded axle 150 rotates in a direction that increases its projection into the inner chamber 154, hydraulic fluid is displaced from the inner chamber 154 and can flow back through the fluid path 320 and the check valve 324 into the first hydraulic sub-chamber 112A.

[0028] 3B shows a detailed view of the actuator system 100 including an exemplary check valve 324 disposed along the fluid path 320 of the hydraulic piston assembly 118 between the internal chamber 154 and the first hydraulic sub-chamber 112A. In this example, the check valve 324 includes a valve core 330 that is urged against a valve seat 332 by a spring element 334 disposed between the valve core and a mounting bracket 336 or other form of valve. Hydraulic fluid of sufficient pressure within the internal chamber 154 overcomes the spring force provided by the spring element 334 and displaces the valve core 330 from the valve seat 332, thereby allowing hydraulic fluid to flow through the valve to the first hydraulic sub-chamber 112A via the fluid path 320. It will be understood that other suitable types or configurations of one-way in-line check valves may be used for the check valve 324.

[0029] Figure 4 is a flow diagram illustrating an example method 400 for controlling a dual independent hybrid actuator system, including the actuator system 100 of Figure 1. The method 400 may be performed, by way of example, by the electronic control system 170 of Figure 1.

[0030] In at least some examples, the method 400 may include calibrating the actuator system at step 410. As an example of calibration, the piston rod 122 may be extended and retracted through its range of motion, and sensor measurements may be captured and recorded by the electronic control system throughout the operating range of motion. For example, if the electric motor 140 forms a stepper motor, the rotational positioning data obtained throughout the operating range of the piston rod's motion may be mapped by the electronic control system, such that the electronic control system can later refer to the mapped data to identify the current position of the piston rod at a particular time (i.e., the actuator position). As another example, the position sensors 148A and 148B of FIG. 1 allow the electronic control system to measure and determine an amount of rotation of the motor shaft 142 that can be mapped to the operating range of the piston rod's motion. Again, this initial calibration allows the electronic control system to later refer to the mapped data to identify the current position of the piston rod at a particular time (i.e., the actuator position) by observing the amount of rotation of the motor shaft 142 in either direction. Calibration for other sensors, including sensor 129 that measures the position and / or orientation of the controlled mechanical part, may be performed 410 throughout the motion range of the piston rod. Positioning data captured by the electronic control system from sensor 129 may be mapped to data captured by other sensors, including position sensors 148A and 148B, as well as stepper motor positioning data.

[0031] In step 412, the method includes receiving input data, which may include inputs from sensors (e.g., 129, 148A, 148B, rotational position from electric motor 140 in the case of a stepper motor, etc.), a position reference (Position Ref) representing a control input for a mechanical component (e.g., a flight control surface) controlled by the actuator system, and an indication of a selected operating mode (e.g., from a human operator or a computing system).

[0032] At step 414, the method includes identifying a target change to a state of the actuator system based on the input data received at step 412. As an example, the target change to the state of the actuator system includes a target magnitude (e.g., distance) and a target translation direction (e.g., extension or retraction) representing a difference between a current actuator position and a target actuator position identified based on the input data received at 412. Identifying the target change to the state of the actuator system may be further based on the calibration data obtained at step 410.

[0033] At step 416, the method includes identifying an operational mode of the dual independent hybrid actuator system based on the input data received at step 412. As one example, the input data received at step 412 may include a command identifying an operational mode selected by a human operator or a computing system (e.g., an on-board flight control computing system). As another example, the input data received at step 412 may include data indicative of a fault condition, an error condition, or a normal operating condition (operation without fault).

[0034] In at least some examples, the dual independent hybrid actuator system can be operated in a selected one of a number of operating modes, including an active / active (A / A) mode, an active / no load (A / NL) mode, an active / passive (A / P) mode, or a passive / active (P / A) mode, each of which is indicated by the activity of the hydraulic system compared to the activity of the electric motor (i.e., hydraulic system activity / electric motor activity).

[0035] In active / active mode, the hydraulic system and electric motor are actively controlled and a combined force is generated on the hydraulic piston assembly by both hydraulic force provided by the hydraulic system and mechanical force provided by the electric motor. The active / active mode may be selected to balance the force contributions between the hydraulic system and the electric motor. For example, the hydraulic pressure difference that needs to be generated across the hydraulic piston to provide a given total force may be reduced by the mechanical force contribution from the electric motor. The active / active mode may be used when the hydraulic system cannot generate sufficient hydraulic pressure or when it is desirable to operate with a smaller hydraulic pressure difference. The active / active mode may provide higher dynamics than the active / passive mode.

[0036] In active / no-load mode, the hydraulic system and electric motor are actively controlled, but the hydraulic piston assembly is actuated by hydraulic forces imparted by the hydraulic system, and the electric motor is actuated to reduce, minimize, or eliminate mechanical forces imparted by the electric motor (and its drivetrain) to the hydraulic piston assembly, such as friction and drag. Active / no-load mode may be used when the electric motor acts as a backup for the hydraulic system while simultaneously reducing or minimizing the hydraulic differential required to overcome resistance from the electric motor (and its intermediate drivetrain). Active / no-load mode can provide higher dynamics than active / passive mode. At least in some configurations, active / no-load mode consumes less power, reduces ball screw wear, and improves the efficiency of the electrohydraulic servo actuator (EHSA) compared to active / active mode.

[0037] In active / passive mode, the hydraulic system is actively controlled to provide hydraulic force to the hydraulic piston assembly, and the electric motor and its drive train passively follow the movement of the hydraulic piston assembly. Active / passive mode may be used when the electric motor acts as a backup for the hydraulic system while avoiding the control overhead associated with the electric motor.

[0038] In passive / active mode, the electric motor is actively controlled to provide mechanical power to the hydraulic piston assembly and the hydraulic system is not activated or is activated to reduce, minimize, or eliminate hydraulic forces opposing the mechanical power of the electric motor. Passive / active mode may be used when the hydraulic system cannot generate sufficient hydraulic pressure, such as in the event of a hydraulic system failure or partial failure.

[0039] At step 418, the method includes operating the dual independent hybrid actuator system in the operating mode identified at step 416 to achieve the target change to the actuator system state identified at step 418. As an example, the electronic control system controls the hydraulic system and / or an electric motor of the actuator system to move a hydraulic piston assembly to a target actuator position.

[0040] If the operating mode is identified at step 416 as an active / active mode, the method includes controlling operation of one or more electrohydraulic servo valves of the hydraulic system at step 420 to generate a target hydraulic pressure differential between opposite sides of the hydraulic piston that urges the piston rod in a target translation direction at step 422. For example, with respect to the actuator system 100 of FIG. 1 where the target translation direction is the extend direction 102, the hydraulic pressure differential includes a higher hydraulic pressure in the first hydraulic sub-chamber 112A compared to the second hydraulic sub-chamber 112B. In another example where the target translation direction is the retract direction 104, the hydraulic pressure differential includes a higher hydraulic pressure in the second hydraulic sub-chamber 112B compared to the first hydraulic sub-chamber 112A.

[0041] Concurrently with and in coordination with the hydraulic force provided by the hydraulic differential at step 422, the method includes controlling operation of the electric motor in a target rotational direction at step 424 to urge the piston rod in the target translational direction. Controlling operation of the electric motor at step 424 includes powering the electric motor in an amount and phase sufficient to rotate the motor shaft in the target rotational direction, thereby rotating a threaded axle engaging the hydraulic piston assembly. The total force urging the piston rod in the target translational direction includes the sum of a hydraulic force provided by the hydraulic differential and a mechanical force provided by the electric motor to the hydraulic piston assembly. The total force provided by the hydraulic force and the mechanical force may result in movement of the hydraulic piston assembly in the target translational direction where the total force exceeds forces opposing such movement, e.g., air loads on a flight control surface.

[0042] If the operating mode is identified as an active / no load mode, the method includes controlling operation of one or more electrohydraulic servo valves of the hydraulic system at step 430 to generate a target hydraulic pressure differential that urges the piston rod in a target translational direction at step 432. Simultaneously with and in coordination with the hydraulic force provided by the hydraulic pressure differential at step 432, the method includes controlling operation of the electric motor to rotate the motor shaft in a target rotational direction corresponding to the target translational direction of the piston rod in a manner that reduces, minimizes, or eliminates resistance presented by the motor (and its intermediate drive train) to movement of the piston rod at step 434. Because in the active / no load mode, an electric motor is not used to provide mechanical force to the hydraulic piston assembly, for a particular total force provided to the hydraulic piston assembly, the hydraulic force in the active / no load mode will be greater than in the active / active mode.

[0043] If the operating mode is identified as an active / passive mode, the method includes controlling operation of one or more electrohydraulic servo valves of the hydraulic system, at step 440, to generate a target hydraulic pressure differential that urges the piston rod in a target translational direction, at step 442, and the electric motor is not actuated (i.e., no power is provided to the electric motor to induce additional mechanical force on the hydraulic piston assembly), at step 444. As the hydraulic piston assembly moves in the active / passive mode due to the hydraulic pressure differential, the electric motor (and its intermediate drive train) is free to rotate and resistance to such rotation is provided to the hydraulic piston assembly.

[0044] If the operating mode is identified as a passive / active mode, the method includes controlling operation of the electric motor at step 450 to rotate the motor shaft in a target rotational direction at step 454 to urge the piston rod in a target translational direction. At step 452, an inhibiting pressure differential that would cause the hydraulic system to not operate or urge the piston rod in a direction opposite to the target translational direction is reduced, minimized, or eliminated by controlling operation of one or more electrohydraulic servo valves and / or pressure relief valves of the hydraulic system. For example, in relation to the actuator system 100 of FIG. 1 where the target translational direction is the extend direction 102, the hydraulic pressure in the second hydraulic sub-chamber 112B can be reduced, thereby reducing the hydraulic force on the hydraulic piston assembly that opposes the mechanical force imparted by the electric motor. In another example where the target translational direction is the retract direction 104, the hydraulic pressure in the first hydraulic sub-chamber 112A can be reduced, thereby reducing the hydraulic force on the hydraulic piston assembly that opposes the mechanical force imparted by the electric motor.

[0045] From any of the operational modes 420, 430, 440, and 450 performed as part of operation 418, the method returns to step 412 at a subsequent time to receive additional input data. As an example, in response to the hydraulic system being unable to generate a target hydraulic pressure differential between the two sides of the hydraulic piston as identified based on the additional input data received in step 412, the power supplied to the electric motor may be increased to rotate the motor shaft in a target rotational direction, thereby moving the piston rod in a target translational direction to a target position, either alone or in combination with the hydraulic pressure differential provided by the hydraulic system. The power supplied to the electric motor may be increased as a result of a transition between modes, such as from an active / no load mode or an active / passive mode to an active / active mode or a passive / active mode. Conversely, the power supplied to the electric motor may be decreased as a result of a transition from an active / active mode or a passive / active mode to an active / no load mode or an active / passive mode. Thus, during a first control action (e.g., at a first time), one or more electrohydraulic servo valves of the hydraulic system can be actuated to generate a target hydraulic pressure differential that moves an attached piston rod in a target translational direction; and during a second control action (e.g., at a second time), the electric motor can be actuated, with or without hydraulic force contribution from the hydraulic system, to rotate the motor shaft in a target rotational direction, thereby moving the piston rod in the first translational direction.

[0046] FIG. 5 illustrates a schematic of an exemplary control architecture 500 for a dual independent hybrid actuator system, including the actuator system 100 of FIG. 1. The control architecture 500 may be implemented by an electronic control system, such as the electronic control system 170 of FIG. 1, to perform the method 400 of FIG. 4, or portions thereof. In this example, the control architecture 500 is described in relation to using the dual independent hybrid actuator system 100 of FIG. 1 for a flight control surface as an example of a mechanical component controlled by a piston rod of the actuator system. For example, the actuator position may be obtained from the position sensors 148A and 148B, or from an electric motor in the case of a stepper motor, and the control surface position may be obtained from the sensor 129 of FIG. 1. During fault-free operation, position control of the control surface may be achieved by a proportional position control loop of an electro-hydraulic servo actuator (EHSA) controller, while load control may be achieved by an additional proportional position load control loop for an electric motor driven ball screw (EMDLS) as an external cascade to the position control loop. In Figure 5, a ball screw actuator is provided as an example of the electric motor 140 of Figure 1. Thus, in the event of EHSA failure or loss of hydraulic power, control can be switched to EMDLS position control. Figure 5 further illustrates an example of a mode selector switch that allows selection between active / passive (A / P), active / active (A / A), and active / no load (A / NL) operating modes as previously described with reference to Figure 4.

[0047] FIG. 6 illustrates an exemplary planetary gear system 600 that may be included in the drive train 160 of the actuator system 100 of FIG. 1. The planetary gear system 600 includes an outer ring gear 610 that meshes with a number of planetary gears 612, 614, 616, 618, etc., which in turn mesh with a sun gear 620. It will be appreciated that fewer or more planetary gears may be used depending on the implementation. In FIG. 6, the gear teeth are omitted since any suitable gear tooth configuration may be used to achieve a particular gear ratio of the planetary gear system 600. In relation to the actuator system 100, the sun gear 620 is mounted on a sun gear axle 622 having an axis of rotation that is coaxial with the translation axis 125 of FIG. 1. The multiple planetary gears are mounted on a carrier 626 having a carrier axle 624 that protrudes from the opposite side of the planetary gear system 600 as the sun gear axle 622. The carrier axle 624 may also be coaxial with the translation axis 125. As an example, one of the axles 622 or 624 can be mechanically coupled to the motor shaft 142 of the electric motor 140, and the other of the axles 622 or 624 can be mechanically coupled to the screw axle 150 to provide the desired gear ratio.

[0048] In at least some examples, the methods and processes described herein may be coupled to a computing system of one or more computing devices. Figure 7 illustrates an exemplary computing system 700 that can implement the method 400 of Figure 4 and the control architecture 500 of Figure 5 for a dual independent hybrid actuator system, including the actuator system 100 of Figure 1. The computing system 700 is an example of an electronic control system for a dual independent hybrid actuator system, such as the electronic control system 170 of Figure 1. In Figure 7, the computing system 700 is illustrated in simplified form as including a logic machine 710, a memory machine 712, and an input / output subsystem 714.

[0049] The logical machine 710 includes one or more physical devices configured to execute instructions. For example, the logical machine may be configured to execute instructions that are part of one or more applications, services, programs, routines, libraries, objects, components, data structures, or other logical constructs. Such instructions may be implemented to perform a task, implement a data type, transform the state of one or more components, achieve a technical effect, or otherwise arrive at a desired result.

[0050] The logical machine 710 may include one or more processors configured to execute software instructions. Additionally or alternatively, the logical machine 710 may include one or more hardware or firmware logical machines configured to execute hardware or firmware instructions. The processors of the logical machines may be single-core or multi-core, and the instructions executed therein may be configured for sequential, parallel, and / or distributed processing. Individual components of the logical machine may optionally be distributed among two or more separate devices, which may be remotely located and / or configured for cooperative processing. For example, the logical machine 710 may be implemented as a first logical machine component that controls the operation of the hydraulic system 134 and as a second logical machine component that controls the operation of the electric motor 140.

[0051] The storage machine 712 includes one or more physical devices configured to hold instructions 720 and / or other data 722 executable by the logic machine 710 to implement the methods and operations described herein. When such methods and operations are performed, the state of the storage machine 712 may be transformed, for example, to hold different data. The storage machine 712 may include one or more removable and / or embedded devices. The storage machine 712 may include optical memory (e.g., CDs, DVDs, etc.), semiconductor memory (e.g., RAM, EPROM, EEPROM, etc.), and / or magnetic memory (e.g., hard disk drives, floppy disk drives, tape drives, MRAM, etc.). The storage machine 712 may include volatile, non-volatile, dynamic, static, read / write, read-only, random access, sequential access, location addressable, file addressable, and / or content addressable devices. Individual components of the storage machine may optionally be distributed among two or more separate devices, which may be located remotely and / or configured for cooperative processing. For example, the memory machine 712 may be implemented as a first memory machine component that holds instructions and / or data for controlling the operation of the hydraulic system 134 and as a second memory machine component that holds instructions and / or data for controlling the operation of the electric motor 140.

[0052] Aspects of the logic machine 710 and the storage machine 712 may be integrated together into one or more hardware logic components, which may include field programmable gate arrays (FPGAs), program specific and application specific integrated circuits (PASICs / ASICs), program specific and application specific standard products (PSSPs / ASSPs), systems on a chip (SOCs), complex programmable logic devices (CPLDs), and the like.

[0053] The input / output subsystem 714 can include or interface with one or more input devices and / or output devices. Examples of input devices include the various sensors described herein (e.g., 129, 148A, 148B, electric motor 140 as a stepper motor to identify rotational position, etc.), user input devices (e.g., aircraft cockpit controls, computer mouse or controller, touch screen, natural language interface, etc.), communication interfaces (e.g., with another computing device), etc. Examples of output devices include electric motor 140, brakes 149, hydraulic pump 136, servo valve 138, pressure relief valves for hydraulic systems, user output interfaces (e.g., gauges, graphic display devices, audio speakers, indicator lights), etc.

[0054] Examples of the subject matter of the present disclosure are described in the following enumerated subsections.

[0055] A.1 A dual independent hybrid actuator system comprising: an actuator body defining a hydraulic chamber therein, the actuator body further defining a first hydraulic fluid passageway in fluid communication with the hydraulic chamber; a hydraulic piston assembly including a hydraulic piston disposed within the hydraulic chamber dividing the hydraulic chamber into a first hydraulic subchamber in fluid communication with the first hydraulic fluid passageway and a second hydraulic subchamber in fluid communication with the second hydraulic fluid passageway; and a piston rod attached to the hydraulic piston and passing through the second hydraulic subchamber, the piston rod having a distal end that protrudes outwardly from the actuator body; an electric motor attached to the actuator body, the electric motor having a motor shaft; and a threaded axle mechanically coupled to the motor shaft of the electric motor, the threaded axle passing through the first hydraulic subchamber and engaging a threaded port formed in the hydraulic piston assembly.

[0056] A.2 The dual independent hybrid actuator system of claim A.1, wherein rotation of the motor shaft of the electric motor in a first rotational direction causes the hydraulic piston to move in a first translational direction within the hydraulic chamber, causing the distal end of the piston rod to extend outwardly from the actuator body; and rotation of the motor shaft of the electric motor in a second rotational direction opposite the first rotational direction causes the hydraulic piston to move in a second translational direction opposite the first translational direction within the hydraulic chamber, causing the piston rod to retract inwardly toward the actuator body.

[0057] A.3 The dual independent hybrid actuator system of clause A.2, wherein a first pressure differential between the first and second hydraulic subchambers causes the hydraulic piston to move in a first translational direction when the first hydraulic subchamber has a higher hydraulic pressure than the second hydraulic subchamber; and a second pressure differential between the first and second hydraulic subchambers causes the hydraulic piston to move in a second translational direction opposite the first translational direction when the second hydraulic subchamber has a higher hydraulic pressure than the first hydraulic subchamber.

[0058] A.4 The dual independent hybrid actuator system of clause A.3, further comprising: a hydraulic system in communication with the first hydraulic fluid passageway and the second hydraulic fluid passageway of the actuator body; and a control system that coordinates operation of the electric motor and an electro-hydraulic servo valve of the hydraulic system to increase hydraulic pressure in the first hydraulic subchamber relative to the second hydraulic subchamber to achieve a first pressure differential and simultaneously actuate the electric motor to rotate in a first rotational direction and increase hydraulic pressure in the second hydraulic subchamber relative to the first hydraulic subchamber to achieve a second pressure differential and simultaneously actuate the electric motor to rotate in a second rotational direction.

[0059] A.5 A dual independent hybrid actuator system according to any of clauses A.1 to A.4, wherein the screw axle is coaxial with the piston rod or with the translation axis of the piston rod.

[0060] A.6 A dual independent hybrid actuator system as described in clause A.5, wherein the motor shaft is coaxial with the piston rod or with the translation axis of the piston rod.

[0061] A.7. The dual independent hybrid actuator system of any of clauses A.1 to A.6, wherein the hydraulic piston assembly further includes a ball screw nut defining a threaded port, and the threaded axle forms a ball screw shaft.

[0062] A.8. The dual independent hybrid actuator system of any of clauses A.1 to A.7, wherein the hydraulic piston assembly defines an internal chamber within a body of the hydraulic piston and / or piston rod that accommodates a portion of the threaded axle protruding from the threaded port; the body of the hydraulic piston and / or piston rod defines a fluid pathway between the internal chamber and a first hydraulic sub-chamber that is independent of the threaded port; and the hydraulic piston assembly further includes an in-line check valve disposed along the fluid pathway, thereby providing greater resistance to hydraulic fluid flowing through the in-line check valve toward the internal chamber compared to hydraulic fluid flowing from the internal chamber through the in-line check valve.

[0063] A.9 The dual independent hybrid actuator system of any of clauses A.1 to A.8, further comprising a drive train, wherein the screw axle is mechanically coupled to a motor shaft of the electric motor via the drive train; and the drive train provides a non-parity effective gear ratio between the motor shaft and the screw axle.

[0064] A.10 A dual independent hybrid actuator system as described in clause A.9, wherein a non-parity effective gear ratio reduces the rotational speed of the screw axle compared to the rotational speed of the motor shaft.

[0065] A.11 A dual independent hybrid actuator system as described in clause A.9, wherein the drive train includes a planetary gear system.

[0066] A.12 A dual independent hybrid actuator system according to any of clauses A.1 to A.11, wherein the actuator body in combination with the piston rod forms a linkage including a first bearing attachment point at a distal end of the piston rod and a second bearing attachment point at a distal end of the actuator body opposite the first bearing attachment point.

[0067] B.1 A method of controlling a dual independent hybrid actuator system, the method comprising: controlling operation of an electro-hydraulic servo valve of the hydraulic system to create a first hydraulic pressure differential between opposite sides of a hydraulic piston to move a piston rod attached to the hydraulic piston in a first translational direction; and controlling operation of an electric motor having a motor shaft mechanically coupled to the hydraulic piston via a threaded axle during movement of the piston rod in the first translational direction, wherein controlling operation of the electric motor includes providing power to the electric motor to rotate the motor shaft in a first rotational direction, thereby moving the piston rod in the first translational direction in coordination with a force provided by the first hydraulic pressure differential or reducing resistance by the motor to movement of the piston rod in the first translational direction.

[0068] B.2 The method of claim 1, further comprising increasing power supplied to the electric motor in response to the hydraulic system being unable to generate a first hydraulic pressure differential between opposite sides of the hydraulic piston to rotate the motor shaft in a first rotational direction to move the piston rod in a first translational direction to a target position.

[0069] B.3 The method of claim B.1 or B.2, further comprising: controlling operation of an electrohydraulic servo valve of the hydraulic system to generate a second hydraulic pressure differential between opposite sides of the hydraulic piston to move the piston rod in a second translational direction opposite to the first translational direction; and controlling operation of the electric motor by supplying power to the electric motor to rotate the motor shaft in a second rotational direction opposite to the first rotational direction during movement of the piston rod in the second translational direction, thereby moving the piston rod in the second translational direction in coordination with the force provided by the second hydraulic pressure differential or reducing the resistance provided by the motor to movement of the piston rod in the second translational direction.

[0070] B.4 The method of claim B.3, further comprising increasing power supplied to the electric motor in response to the hydraulic system being unable to generate a second hydraulic pressure differential between the opposite sides of the hydraulic piston to rotate the motor shaft in a second rotational direction to move the piston rod in a second translational direction to a target position.

[0071] B.5 The method of any of clauses B.1 to B.4, wherein controlling operation of the electric motor includes supplying power to the electric motor to rotate the motor shaft in a first rotational direction to eliminate resistance by the motor to movement of the piston rod in a first translational direction.

[0072] C.1 A method of controlling a dual independent hybrid actuator system, the method comprising: controlling operation of an electro-hydraulic servo valve of a hydraulic system to generate a first hydraulic pressure differential between opposite sides of a hydraulic piston to move a piston rod attached to the hydraulic piston in a first translational direction during a first control action; and controlling operation of an electric motor having a motor shaft mechanically coupled to the hydraulic piston via a threaded axle to rotate the motor shaft in a first rotational direction and move the piston rod in the first translational direction during a second control action.

[0073] C.2 The method of clause C.1, wherein a second control action is performed in response to the hydraulic system being unable to generate a first hydraulic pressure differential between opposite sides of the hydraulic piston during the first control action.

[0074] C.3 The method of claim C.1 or C.2, wherein the second control action is performed simultaneously with the first control action.

[0075] It is understood that the configurations and / or techniques described herein are exemplary in nature, and that these specific examples should not be considered in a limiting sense, as many variations are possible. The specific methods and operations described herein may represent one or more of any number of processing strategies. Thus, the various operations shown and / or described may be performed in the sequence shown and / or described, in other sequences, in parallel, or omitted. Similarly, the order of the operations described above may be changed depending on the implementation. The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various configurations and techniques, as well as other forms, functions, operations, and / or properties disclosed herein, and all equivalents thereof. [Explanation of symbols]

[0076] 100 dual independent hybrid actuator system, 102 first translation direction, 102 extension direction, 104 second translation direction, 104 retraction direction, 110 actuator body, 110A cover portion, 111 opening, 112 hydraulic chamber, 112A first hydraulic sub-chamber, 112B second hydraulic sub-chamber, 113 seals and / or bearings, 114 first hydraulic fluid passage, 116 second hydraulic fluid passage, 118 hydraulic piston assembly, 120 hydraulic piston, 121 seals and / or bearings, 122 piston rod, 123 seals and / or bearings, 124 distal end, 125 translation shaft, 126 linkage, 127 mechanical part, 128 first bearing attachment point, 129 position sensor, 130 second bearing attachment point, 132 distal end, 134 hydraulic system, 136 Hydraulic pump, 138 electrohydraulic servo valve, 140 electric motor, 142 motor shaft, 144 first direction of rotation, 145A axial bearing, 145B axial bearing, 146 first direction of rotation, 148A position sensor, 148B position sensor, 149 brake, 149A electric brake, 149B electric brake, 150 threaded axle, 152 threaded port, 154 inner chamber, 160 drive train, 162 output shaft, 164 axial bearing, 170 electronic control system, 200 electric brake, 210 housing, 212 coil, 214 drive cup, 216 support plate, 218 armature, 220 end plate, 222 friction disc, 224 spring, 310 ball screw nut, 312 ball screw shaft, 314 external thread race, 316 internal threaded race, 318 ball bearing, 320 fluid path, 322 opening, 324 check valve, 330 valve core, 332 valve seat, 334 spring element, 336 mounting bracket, 500 control architecture, 600 planetary gear system, 610 outer ring gear, 612 planetary gear, 614 planetary gear, 616 planetary gear, 618 planetary gear, 620 sun gear, 622 sun gear axle, 624 carrier axle, 626 carrier, 700 computing system, 710 logic machine, 712 memory machine, 714Input / Output Subsystem, 720 Instruction, 722 Data

Claims

1. an actuator body defining a hydraulic chamber therein, the actuator body further defining a first hydraulic fluid passageway and a second hydraulic fluid passageway in fluid communication with the hydraulic chamber; A hydraulic piston assembly, comprising: a hydraulic piston disposed within said hydraulic chamber and dividing said hydraulic chamber into a first hydraulic sub-chamber in fluid communication with said first hydraulic fluid passage and a second hydraulic sub-chamber in fluid communication with said second hydraulic fluid passage; a piston rod attached to the hydraulic piston and passing through the second hydraulic sub-chamber, the piston rod having a distal end projecting outwardly from the actuator body; a hydraulic piston assembly including: an electric motor attached to the actuator body, the electric motor having a motor shaft; and a threaded axle mechanically coupled to the motor shaft of the electric motor, the threaded axle passing through the first hydraulic subchamber and engaging a threaded port formed in the hydraulic piston assembly; and Equipped with the hydraulic piston assembly defines an internal chamber within a body of the hydraulic piston and / or the piston rod that accommodates a portion of the threaded axle protruding from the threaded port; the body of the hydraulic piston and / or the piston rod defines a fluid path between the internal chamber and the first hydraulic sub-chamber that is independent of the threaded port; The hydraulic piston assembly further includes an in-line check valve disposed along the fluid path thereby providing a greater resistance to hydraulic fluid flowing through the in-line check valve toward the internal chamber compared to hydraulic fluid flowing from the internal chamber through the in-line check valve.

2. rotation of the motor shaft of the electric motor in a first rotational direction causes the hydraulic piston to move in a first translational direction within the hydraulic chamber causing the distal end of the piston rod to extend outwardly from the actuator body; 2. The dual independent hybrid actuator system of claim 1, wherein rotation of the motor shaft of the electric motor in a second rotational direction opposite to the first rotational direction causes the hydraulic piston to move within the hydraulic chamber in a second translational direction opposite to the first translational direction to retract the piston rod inwardly toward the actuator body.

3. a first pressure differential between the first hydraulic subchamber and the second hydraulic subchamber causes the hydraulic piston to move in the first translational direction when the first hydraulic subchamber has a higher hydraulic pressure than the second hydraulic subchamber; 3. The dual independent hybrid actuator system of claim 2, wherein a second pressure differential between the first hydraulic subchamber and the second hydraulic subchamber causes the hydraulic piston to move in the second translational direction opposite the first translational direction when the second hydraulic subchamber has a higher hydraulic pressure than the first hydraulic subchamber.

4. a hydraulic system in communication with the first hydraulic fluid passageway and the second hydraulic fluid passageway of the actuator body; a control system for coordinating operation of the electric motor and an electrohydraulic servo valve of the hydraulic system, comprising: increasing hydraulic pressure in the first hydraulic subchamber relative to the second hydraulic subchamber to achieve the first pressure differential while simultaneously energizing the electric motor to rotate in the first rotational direction; increasing hydraulic pressure in the second hydraulic subchamber relative to the first hydraulic subchamber to achieve the second pressure differential and simultaneously actuating the electric motor to rotate in the second rotational direction. A control system; 4. The dual independent hybrid actuator system of claim 3, further comprising:

5. 5. The dual independent hybrid actuator system according to claim 1, wherein the screw axle is coaxial with the piston rod or with a translation axis of the piston rod.

6. 6. The dual independent hybrid actuator system of claim 5, wherein the motor shaft is coaxial with the piston rod or with the translation axis of the piston rod.

7. the hydraulic piston assembly further includes a ball screw nut defining the threaded port; The screw axle forms a ball screw shaft. A dual independent hybrid actuator system according to any one of claims 1 to 6.

8. Equipped with a drivetrain, the screw axle is mechanically coupled to the motor shaft of the electric motor via the drive train; the drive train providing a non-parity effective gear ratio between the motor shaft and the screw axle; A dual independent hybrid actuator system according to any one of claims 1 to 7.

9. 9. The dual independent hybrid actuator system of claim 8, wherein the non-parity effective gear ratio reduces the rotational speed of the screw axle relative to the rotational speed of the motor shaft.

10. The dual independent hybrid actuator system of claim 8 or 9, wherein the drive train includes a planetary gear system.

11. the actuator body in combination with the piston rod forms a linkage; The linkage is a first bearing attachment point at the distal end of the piston rod; and a second bearing attachment point at a distal end of the actuator body opposite the first bearing attachment point; 11. The dual independent hybrid actuator system of claim 1 , comprising:

12. 1. A method of controlling a dual independent hybrid actuator system, the dual independent hybrid actuator system comprising: an actuator body defining a hydraulic chamber therein, the actuator body further defining a first hydraulic fluid passageway and a second hydraulic fluid passageway in fluid communication with the hydraulic chamber; A hydraulic piston assembly, comprising: a hydraulic piston disposed within said hydraulic chamber and dividing said hydraulic chamber into a first hydraulic sub-chamber in fluid communication with said first hydraulic fluid passage and a second hydraulic sub-chamber in fluid communication with said second hydraulic fluid passage; a piston rod attached to the hydraulic piston and passing through the second hydraulic sub-chamber, the piston rod having a distal end projecting outwardly from the actuator body; and a hydraulic piston assembly comprising: - controlling operation of an electrohydraulic servo valve of a hydraulic system to generate a first hydraulic pressure differential across the hydraulic piston to move the piston rod attached to the hydraulic piston in a first translational direction; - controlling operation of an electric motor having a motor shaft mechanically coupled to the hydraulic piston via a threaded axle during movement of the piston rod in the first translational direction; Including, The step of controlling operation of the electric motor includes providing electrical power to the electric motor to rotate the motor shaft in a first rotational direction, thereby moving the piston rod in the first translational direction in coordination with a force provided by the first hydraulic differential; or reducing resistance by the electric motor to movement of the piston rod in the first translational direction; The method further includes the steps of: the hydraulic piston assembly defines an internal chamber within a body of the hydraulic piston and / or the piston rod that receives a portion of the threaded axle protruding from a threaded port formed in the hydraulic piston assembly; the body of the hydraulic piston and / or the piston rod defines a fluid path between the internal chamber and the first hydraulic sub-chamber that is independent of the threaded port; the hydraulic piston assembly further includes an in-line check valve disposed along the fluid path thereby providing a greater resistance to hydraulic fluid flowing through the in-line check valve toward the internal chamber compared to hydraulic fluid flowing from the internal chamber through the in-line check valve.

13. increasing the power supplied to the electric motor to rotate the motor shaft in the first rotational direction to move the piston rod in the first translational direction to a target position in response to the hydraulic system being unable to generate the first hydraulic pressure differential between the opposite sides of the hydraulic piston. The method of claim 12 further comprising:

14. controlling operation of the electrohydraulic servo valve of a hydraulic system to create a second hydraulic pressure differential across the hydraulic piston to move the piston rod in a second translational direction opposite the first translational direction; controlling operation of the electric motor by supplying electrical power to the electric motor to rotate the motor shaft in a second rotational direction opposite to the first rotational direction during movement of the piston rod in the second translational direction; Further comprising: moving the piston rod in the second translational direction in coordination with a force provided by the second hydraulic differential; or reducing resistance by the electric motor to movement of the piston rod in the second translational direction; 14. The method according to claim 12 or 13.

15. increasing the power supplied to the electric motor to rotate the motor shaft in the second rotational direction to move the piston rod in the second translational direction to a target position in response to the hydraulic system being unable to generate the second hydraulic pressure differential between the opposite sides of the hydraulic piston. The method of claim 14 further comprising:

16. 16. The method of any one of claims 12 to 15, wherein controlling operation of the electric motor comprises supplying power to the electric motor to rotate the motor shaft in a first rotational direction to eliminate resistance by the electric motor to movement of the piston rod in the first translational direction.

17. 1. A method of controlling a dual independent hybrid actuator system, the dual independent hybrid actuator system comprising: an actuator body defining a hydraulic chamber therein, the actuator body further defining a first hydraulic fluid passageway and a second hydraulic fluid passageway in fluid communication with the hydraulic chamber; A hydraulic piston assembly, comprising: a hydraulic piston disposed within said hydraulic chamber and dividing said hydraulic chamber into a first hydraulic sub-chamber in fluid communication with said first hydraulic fluid passage and a second hydraulic sub-chamber in fluid communication with said second hydraulic fluid passage; a piston rod attached to the hydraulic piston and passing through the second hydraulic sub-chamber, the piston rod having a distal end projecting outwardly from the actuator body; and a hydraulic piston assembly comprising: During a first control operation, controlling operation of an electrohydraulic servo valve of a hydraulic system to generate a first hydraulic pressure differential across the hydraulic piston to move the piston rod attached to the hydraulic piston in a first translational direction; during a second control operation, controlling operation of an electric motor having a motor shaft mechanically coupled to the hydraulic piston via a threaded axle to rotate the motor shaft in a first rotational direction and move the piston rod in the first translational direction; Including, the hydraulic piston assembly defines an internal chamber within a body of the hydraulic piston and / or the piston rod that receives a portion of the threaded axle protruding from a threaded port formed in the hydraulic piston assembly; the body of the hydraulic piston and / or the piston rod defines a fluid path between the internal chamber and the first hydraulic sub-chamber that is independent of the threaded port; the hydraulic piston assembly further includes an in-line check valve disposed along the fluid path thereby providing a greater resistance to hydraulic fluid flowing through the in-line check valve toward the internal chamber compared to hydraulic fluid flowing from the internal chamber through the in-line check valve.

18. the second control action is performed in response to the hydraulic system being unable to generate the first hydraulic pressure differential between the opposite sides of the hydraulic piston during the first control action.

20. The method of claim 17.

19. 19. The method of claim 17 or 18, wherein the second control action is performed simultaneously with the first control action.

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