Fault-tolerant multi-turn actuator assembly

Abstract

1. An actuator assembly comprising: an output member rotatable about a central axis relative to a structure; a first actuator having a first stator fixed to the structure and a first rotor rotatable about the central axis relative to the first stator; a second actuator having a second stator coupled to the first rotor such that the second stator rotates about the central axis relative to the first stator with rotation of the first rotor about the central axis, and having a second rotor rotatably coupled to the output member; and a controller configured to, in a failure mode, drive one of the first secondary actuator or the second secondary actuator to selectively control rotation of the output member about the central axis, wherein the other of the first secondary actuator or the second secondary actuator is malfunctioning.

Description

[Technical field]

[0001] The present invention relates generally to the field of redundant flight control actuator systems, and more particularly to electromechanical redundant actuator systems. [Background technology]

[0002] Redundant actuator systems are commonly known. U.S. Patent No. 8,136,418, issued March 20, 2012, and entitled “Electromechanical Actuating Assembly,” is directed to an assembly capable of operating in multiple fault-tolerant modes.

[0003] U.S. Patent No. 8,136,418, issued March 20, 2012, and titled “Electromechanical Actuating Assembly,” is directed to an assembly capable of operating in multiple fault-tolerant modes.

[0004] U.S. Patent No. 7,122,926, issued Oct. 17, 2016, and titled “Fault-Tolerant Rotary Actuator,” is directed to an actuator module that houses two actuator subsystems.

[0005] U.S. Patent Application Publication No. 2007 / 0068291, published March 29, 2007 and entitled "Failure-Tolerant Redundant Actuator System," is directed to an actuator system that is resistant to any single point failure.

[0006] U.S. Patent Application Publication No. 2015 / 0081102, published March 19, 2015, and entitled “Actuator System and Method,” is directed to an actuator system having multiple actuators and a linkage including a shared link for rotating a controlled element.

[0007] U.S. Patent No. 9,086,125, titled “Rotary Actuator,” issued July 21, 2015, is directed to an actuator system having multiple actuators and multiple linkages with independent degrees of freedom. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 8,136,418 [Patent Document 2] U.S. Patent No. 7,122,926 [Patent Document 3] US Patent Application Publication No. 2007 / 0068291 [Patent Document 4] US Patent Application Publication No. 2015 / 0081102 [Patent Document 5] U.S. Patent No. 9,086,125 Summary of the Invention [Means for solving the problem]

[0009] For purposes of illustration only and not by way of limitation, with additional reference to corresponding parts, portions or surfaces of the disclosed embodiments, the present disclosure provides an output member (16) configured to selectively rotate about a rotary output shaft (18) relative to a structure (19) and configured to impart motion to a driven body (20), a first secondary actuator (30) having a first stator (31) and a first rotor (32), the first stator (31) being fixed to the structure (19) and the first rotor (32) being fixed to a second rotor (32) relative to the first stator (31). a first sub-actuator (30) configured to selectively rotate about a first sub-rotation shaft (33) relative to the second stator (51); and a second sub-actuator (50) having a second stator (51) and a second rotor (52), the second rotor (52) configured to selectively rotate about a second sub-rotation shaft (53) relative to the second stator (51), the second stator (51) being configured to selectively rotate about the first stator (31) with the rotation of the first rotor (32) about the first sub-rotation shaft (33) relative to the first stator (31). a second secondary actuator (50) connected to the first rotor (32) for rotation about a first secondary axis (33) relative to the rotor (31), the second rotor (53) being rotationally coupled to the output member; and at least one controller (90, 91A, 91B) configured to drive the first secondary actuator and the second secondary actuator to selectively control rotation of the output member about the rotational output axis within an output angular range of rotational motion about the rotational output axis, wherein the controller is configured in a normal mode to drive the first secondary actuator and the second secondary actuator to selectively control rotation of the output member about the rotational output axis within an output angular range of rotational motion as a function of a sum of rotations of the first rotor and the second rotor about the first secondary axis and the second secondary axis, respectively, relative to the structure, and wherein the controller is configured in a failure mode to drive one of the first secondary actuator or the second secondary actuator to selectively control rotation of the output member about the rotational output axis within an output angular range of rotational motion;At this time, the other of the first sub-actuator or the second sub-actuator is malfunctioning.

[0010] The rotary actuator assembly may include a third secondary actuator (70) having a third stator (71) and a third rotor (72), the third rotor (72) configured to selectively rotate relative to the third stator (71) about a third secondary axis of rotation (73), the third stator (71) being rotationally coupled to the second rotor (52) such that the third stator (71) rotates about the second secondary axis of rotation (53) relative to the second stator (51) with rotation of the second rotor (52) about the second secondary axis of rotation (53) relative to the second stator (51), the third rotor (72) being rotationally coupled to the output member (16) between the second rotor (52) and the output member (16), and the controller (90, 91A, 91B, 91C) is configured to control the rotation of the third secondary actuator (70) in a normal mode. and configured to drive the first secondary actuator, the second secondary actuator, and the third secondary actuator to selectively control rotation of the output member about the rotational output shaft within an output angular range of rotational motion as a function of a sum of rotations of the first rotor, the second rotor, and the third rotor about the first secondary rotational shaft, the second secondary rotational shaft, and the third secondary rotational shaft, respectively, relative to the structure, and the controller is configured to drive at least one of the first secondary actuator, the second secondary actuator, or the third secondary actuator in a failure mode to selectively control rotation of the output member about the rotational output shaft within an output angular range of rotational motion, wherein another one of the first secondary actuator, the second secondary actuator, or the third secondary actuator is malfunctioning.

[0011] The first counter rotating shaft (33) and the second counter rotating shaft (52) may be the same, and the first rotor (32) and the second rotor (52) may be coaxial. The first counter rotating shaft (33), the second counter rotating shaft (53), and the third counter rotating shaft (73) may be the same, and the first rotor (32), the second rotor (52), and the third rotor (72) may be coaxial. The first counter rotating shaft (33), the second counter rotating shaft (53), and the rotary output shaft (18) may be the same.

[0012] The first secondary actuator may include a first secondary actuator housing (34) containing a first stator (31) and fixed relative to the structure, the second secondary actuator may include a second secondary actuator housing (54) containing a second stator (51) and configured to rotate about a first secondary axis (33) relative to the first secondary actuator housing with rotation of the first rotor (32) about the first secondary axis (33) relative to the first secondary actuator housing, and the third secondary actuator may include a third secondary actuator housing (74) containing a third stator (71) and configured to rotate about a second secondary axis (53) relative to the second secondary actuator housing with rotation of the second rotor (52) about the second secondary axis (53) relative to the second secondary actuator housing.

[0013] The first secondary actuator may include a no-back brake (100, 100A) configured to selectively inhibit the first rotor from rotating in a back-drive rotational direction about the first secondary axis relative to the first stator due to malfunction of the first secondary actuator, and the second secondary actuator may include a no-back brake (100, 100B) configured to selectively inhibit the second rotor from rotating in a back-drive rotational direction about the second secondary axis relative to the second stator due to malfunction of the second secondary actuator. The controller may be configured to sense malfunction of the first secondary actuator and in response, stop driving the first secondary actuator, and the controller may be configured to sense malfunction of the second secondary actuator and in response, stop driving the second secondary actuator.

[0014] The first secondary actuator may comprise a first position sensor (35) connected to the controller and configured to sense the angular position of the first rotor about the first secondary axis of rotation relative to the first stator, the second secondary actuator may comprise a second position sensor (55) connected to the controller and configured to sense the angular position of the second rotor about the second secondary axis of rotation relative to the second stator, and the output member may comprise an output position sensor (22) connected to the controller and configured to sense the angular position of the output member about a rotational output axis relative to the structure.

[0015] The rotary actuator system may include a first gear mechanism (38) between the first rotor and the second stator and a second gear mechanism (58) between the second rotor and the output member. The first gear mechanism and the second gear mechanism may each have an input to output ratio greater than one. The first gear mechanism and the second gear mechanism may each comprise planetary gears. The rotary actuator system may include a gear mechanism (38) between the first rotor and the second stator, the first rotor may include an input to the gear mechanism and the second stator may include an output from the gear mechanism. The second stator (51) may rotate about the first secondary axis (33) relative to the first stator (31) at a rotational speed different from the rotational speed of the first rotor (32) about the first secondary axis (33) relative to the first stator (31) with the rotation of the first rotor (32) about the first secondary axis (33) relative to the first stator (31). As a function of the coupling ratio between the second stator and the first rotor, the rotational speed of the second stator about the first secondary axis (33) relative to the first stator may differ from the rotational speed of the first rotor about the first secondary axis (33) relative to the first stator.

[0016] The output angular range of rotational motion (21) may be less than 360 degrees about the rotary output shaft. The rotary actuator system may include a first mechanical stop (60) limiting rotation of the second stator about the first secondary rotational shaft relative to the first stator to an angular limit of the second stator that is less than or equal to 360 degrees. The angular limit of the second stator of the first mechanical stop may be at least twice the output angular range of rotational motion (21) of the output member about the rotary output shaft. The rotary actuator system may include a mechanical stop (23) limiting the output member to the output angular range of rotational motion of the output member about the rotary output shaft. The rotary actuator system may include a first mechanical stop (60) limiting rotation of the second stator about the first minor axis of rotation relative to the first stator to a second stator angle limit that is less than 360 degrees, and a second mechanical stop (80) limiting rotation of the third stator about the second minor axis of rotation relative to the first stator to a third stator angle limit that is less than 360 degrees. The second stator angle limit of the first mechanical stop (60) may be at least twice an output angular range (21) of rotational motion of the output member about the rotary output shaft, and the third stator angle limit of the second mechanical stop (80) may be at least twice the second stator angle limit of the first mechanical stop, and the rotary actuator system may include a mechanical stop (23) limiting the output member to the output angular range of rotational motion of the output member about the rotary output shaft.

[0017] The first secondary actuator may comprise a brushless DC permanent magnet motor configured to drive the first rotor relative to the first stator about a first secondary axis of rotation, and the second secondary actuator may comprise a brushless DC permanent magnet motor configured to drive the second rotor relative to the second stator about a second secondary axis of rotation.

[0018] The driven body may be selected from the group consisting of an aircraft flight control mechanism and an aircraft flight control surface. The driven body may comprise an aircraft flight control surface, which may be selected from the group consisting of an elevator, a rudder, an aileron, a flap, a slat, a stabilizer, and a spoiler. The driven body may comprise an aircraft flight control surface, and the output member may be connected to the flight control surface via a torque tube. The driven body may comprise an aircraft flight control mechanism, which may be selected from the group consisting of a helicopter main rotor, a helicopter tail rotor, a helicopter main rotor swashplate, and a helicopter tail rotor swashplate.

[0019] Malfunctions may include mechanical jams, electrical motor failures, or loss of power. [Brief description of the drawings]

[0020] [Figure 1] FIG. 11 is a schematic diagram of a three-motor embodiment of the improved actuator system connected to a flight control output. [Diagram 2] FIG. 1 is a schematic diagram of a two-motor embodiment of the improved actuator system. [Diagram 3] FIG. 3 is a longitudinal cross-sectional view of a two-motor embodiment of the improved actuator system shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view of the no-back device shown in FIG. [Diagram 5] FIG. 5 is an enlarged cross-sectional perspective view of the no-back device shown in FIG. [Figure 6] FIG. 6 is a partial perspective view of the no-back device shown in FIG. 5. [Figure 7] FIG. 7 is a partial cross-sectional view of the no-back device shown in FIG. 6 in an unlocked position. [Figure 8] FIG. 7 is a partial cross-sectional view of the no-back device shown in FIG. 6 in a locked position. [Figure 9] FIG. 4 is a perspective view of the right end of the two-motor embodiment of the improved actuator system shown in FIG. [Figure 10]FIG. 4 is a block diagram of a controller system for the two-motor embodiment of the improved actuator system shown in FIG. [Figure 11] FIG. 11 is a block diagram of the controller logic for the controller system shown in FIG. [Figure 12] FIG. 2 is a schematic diagram of a three-motor embodiment of the improved actuator system shown in Figure 1. [Figure 13] FIG. 13 is a longitudinal cross-sectional view of a three-motor embodiment of the improved actuator system shown in FIG. [Figure 14] FIG. 14 is a block diagram of a controller system for the three-motor embodiment of the improved actuator system shown in FIG. [Figure 15] FIG. 15 is a block diagram of the controller logic for the controller system shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] At the outset, it should be clearly understood that like reference numerals throughout the several views of the drawings are intended to consistently identify the same structural element, portion, or surface as such elements, portions, or surfaces may be further described or illustrated by the entire written specification of which this detailed description is incorporated as a part. Unless otherwise indicated, the drawings are intended to be read together with the specification (e.g., cross-hatching, part arrangement, proportions, degrees, etc.) and to be considered as part of the entire written specification of the present invention. As used in the following description, the terms "horizontal," "vertical," "left," "right," "upper," and "lower," as well as their adjectival and adverbial derivatives (e.g., "horizontally," "rightwardly," "upwardly," etc.) merely refer to the orientation of the depicted structure when a particular drawing is facing the reader. Similarly, the terms "inwardly" and "outwardly" generally refer to the orientation of a surface relative to its axis of extension or rotation, as appropriate.

[0022] 1, 2, and 12, an improved actuator system is provided having a first two motor embodiment generally indicated at 15 and a second three motor embodiment generally indicated at 115. As shown in FIGS. 2 and 3, the two motor system 15 generally includes an actuator 30, an actuator 50 that is rotationally coupled to the actuator 30 via a no-back device 100A and a gear transmission 38, and an output horn 16 that is rotationally coupled to the actuator 50 via a no-back device 100B and a gear box 78.

[0023] The actuator 30 is supported within a housing 34 and includes a stator 31 and a rotor 32. The housing 34 and stator 31 are fixed to the aircraft frame 19 of the aircraft, and the rotor 32 is driven to rotate relative to the housing 34 and stator 31 about a central axis 18. In this embodiment, the actuator 30 is a brushless DC permanent magnet electric motor having an unpowered no-back device 100A and a planetary gear unit 38. The rotary motor 30 includes an outer non-rotating stator 31 with coil windings and an inner rotor 32 with a permanent magnet 36. The stator 31 is fixed to the motor housing 34 so that the stator 31 does not rotate relative to the housing 34. When current is appropriately applied to the coils of the stator 31 via the leads 42 and the drive unit 91B, a magnetic field is induced. The interaction of the magnetic fields between the stator 31 and the rotor 32 produces a torque that can rotate the shaft 101A. Drive electronics 91A generates a stator magnetic field based on the angular position feedback of resolver 35 and commutates it to vary the speed and direction of motor 30. In response, motor 30 selectively applies torque to rotor 32 in either direction about axis 18 at various speeds. This drives rotor 32 to selectively rotate about axis of rotation 33 relative to stator 31 and housing 34.

[0024] The rotor 32 is rotatably coupled to a no-back input shaft 101A of a no-back device 100A. As shown in Figures 4-6, the no-back device 100A includes a spring 105 acting between an upper bearing plate 103 and a lower lock plate 104, two inclined ramp notches 109 and an input shaft cam 110, a lock pin 106 on the plate 104, and a lock slot 108 on the housing 112. As shown in Figure 8, when no torque is applied from the input shaft 101 to the shaft cam 110, the lock plate 104 is biased by the spring 105 to a lowered position, with the lock pin 106 seated in the corresponding housing slot 108, which does not allow rotation of the output shaft 102A about the central axis 18 relative to the housing 112. This is the locked position. As shown in FIG. 7, when torque is applied to rotate the shaft 32 in either direction about the axis 18, such rotation causes the shaft cam 110 to abut against one of the inclined surfaces (depending on the direction of rotation) of the corresponding inclined notch 109 and to ride out of the corresponding notch 109, which in turn forces the lock plate 104 upward, compresses the spring 105, and moves the pin 106 out of the corresponding lock slot 108 in the housing 112. This allows the output shaft 102A to rotate about the central axis 18 relative to the housing 112, compressing the spring 105, which causes the output shaft 102A to rotate with the input shaft 101A. This is the unlocked position. Thus, in the absence of driving torque on the input shaft 101A from the motor 30 and rotor 32, the output shaft 102A is prevented from rotating by the spring 105, which effectively grounds the output shaft 102A to the fixed structure 112 through the plate 104 and the lock pin 106. When torque is applied to the input shaft 101A from the rotor 32, the spring 105 is compressed, the pin 106 is released from the fixed structure 112, and the output shaft 102A is engaged, transmitting power from the input shaft 101A to the output shaft 102A.

[0025] The output shaft 102A of the no-back device 100A is in turn rotationally coupled to a gear box 38. In this embodiment, the gear box 38 includes an input gear shaft that is rotationally coupled to the output shaft 102A of the no-back device 100A, an output gear shaft 39 connected to the housing 54, and a planetary gear train between the input gear shaft and the output gear shaft 39. In this embodiment, the input to output ratio of the gear box 38 is greater than 1, preferably 120:1.

[0026] Other rotary motors or actuators, such as stepper motors, brush motors, induction motors, rotary hydraulic actuators, or the like, may alternatively be used. Also, other no-back devices, including but not limited to powered no-back devices, may alternatively be used. Additionally, other gear transmissions, or rotary couplings, such as belt couplings or other similar couplings, may be used to achieve the desired gear or speed ratios, or alternatively, no gears may be used.

[0027] The output gear shaft 39 of the gear mechanism 38 is in turn rigidly connected to a housing 54 of the motor 50. The housing 54 is rotationally supported by the aircraft frame 19 such that the housing 54 rotates about axis 18 with rotation of the output shaft 39 of the gear mechanism 38, which is rotationally coupled to the rotor 32 of the motor 30. When the rotor 32 of the motor 30 is not rotating relative to the frame 19 and / or the no-back device 100A is in a locked position, the housing 54 does not rotate relative to the frame 19 and the motor housing 34. When the no-back device 100A is in an unlocked position, the housing 54 rotates about axis 18 with rotation of the rotor 32 relative to the aircraft frame 19 and the motor housing 34 as a function of the coupling ratio between the rotor 32 and the output gear shaft 39 of the gear mechanism 38.

[0028] The actuator 50 is supported within a housing 54 and includes a stator 51 and a rotor 52. The stator 51 is fixed to the housing 54, and the rotor 52 is driven to rotate relative to the housing 54 and the stator 51 about a central axis 18. In this embodiment, the actuator 50 is a brushless DC permanent magnet electric motor having an unpowered no-back device 100B and a planetary gear unit 58. The rotary motor 50 includes an outer non-rotating stator 51 with coil windings and an inner rotor 52 with permanent magnets 56. The stator 51 is fixed to the motor housing 54 so that the stator 51 does not rotate relative to the housing 54. When current is appropriately applied to the coils of the stator 51 via the leads 62 and the drive unit 91B, a magnetic field is induced. The interaction of the magnetic fields between the stator 51 and the rotor 52 produces a torque that can rotate the shaft 101B. Drive electronics 91B generates a stator magnetic field based on the angular position feedback of resolver 55 and commutates it to vary the speed and direction of motor 50. In response, motor 50 selectively applies torque to rotor 52 in either direction about axis 18 at various speeds. This drives rotor 52 to selectively rotate about axis of rotation 53 relative to stator 51 and housing 54.

[0029] The rotor 52 is rotationally coupled to a no-back input shaft 101B of the no-back device 100B. The no-back device 100B is substantially identical in configuration to the no-back device 100A. Thus, in the absence of driving torque from the motor 50 and input shaft 52 to the input shaft 101B, the output shaft 102B is prevented from rotating by a spring 105 which effectively grounds the output shaft 102B to the housing 54 via a plate 104 and a lock pin 106. When torque is applied to the input shaft 101B from the rotor 52, the spring 105 is compressed, the pin 106 is released from the housing 54, and the output shaft 102B is engaged, allowing power to be transmitted from the input shaft 101B to the output shaft 102B.

[0030] The output shaft 102B of the no-back device 100B is in turn rotationally coupled to the gear transmission 58. The gear transmission 58 is of substantially the same configuration as the gear transmission 38. In this embodiment, the input to output ratio of the gear box 58 is greater than 1, preferably 120:1.

[0031] Other rotary motors or actuators, such as stepper motors, brush motors, induction motors, rotary hydraulic actuators, or the like, may alternatively be used. Also, other no-back devices, including but not limited to powered no-back devices, may alternatively be used. Additionally, other gear transmissions, or rotary couplings, such as belt couplings or other similar couplings, may be used to achieve the desired gear or speed ratios, or alternatively, no gears may be used.

[0032] The output gear shaft 59 of the gear mechanism 58 is in turn rigidly connected to the output horn 16. The output horn 16 is rotationally supported by the aircraft frame 19 such that the output horn 16 rotates about axis 18 with rotation of the output shaft 59 of the gear mechanism 58, which is rotationally coupled to the rotor 52 of the motor 50. When the rotor 52 of the motor 50 is not rotating relative to the motor housing 54 and / or the no-back device 100B is in a locked position, the output horn 16 does not rotate relative to the housing 54. When the no-back device 100B is in an unlocked position, the output horn 16 rotates about axis 18 relative to the housing 54 with rotation of the rotor 52 relative to the motor housing 54 as a function of the coupling ratio between the rotor 52 and the output gear shaft 59 of the gear mechanism 58.

[0033] 10 and 11, controller 90 is connected to motor drives 91A and 91B and monitors 122 actuators 30 and 50 and provides commands to actuators 30 and 50 to move output horn 16 to a desired position by controlling the corresponding rotation of rotor 32 relative to stator 31 and motor housing 34 and the rotation of rotor 52 relative to stator 51 and motor housing 54. In normal mode 120, actuators 30 and 50 are controlled to rotate output horn 16 and move flight control output 20 via linkage 25 as a function of the sum of the rotation of rotor 32 and rotor 52 relative to frame 19. However, in motor failure mode 121, either the actuator 30 may be controlled to rotate the output horn 16 and flight control output 20 as a function of the amount of rotation of the rotor 32 relative to the frame 19 when the actuator 50 fails, or the actuator 50 may be controlled to rotate the output horn 16 and flight control output 20 as a function of the amount of rotation of the rotor 52 relative to the frame 19 when the actuator 30 fails. Thus, actuators 30 and 50 have the characteristic that they cannot be back-driven following a critical actuator failure, and the system provides maximum flight control performance in the event of an actuator failure.

[0034] During normal operation 120, both actuators 30 and 50 are used to rotate the output horn 16 and flight control output 20 relative to the frame 19. This is sometimes referred to as an active-active scheme, and is the preferred scheme of operation during normal operation 120. However, if the actuator 50 fails and is no longer powered or operable 124 due to the no-back mechanism 100B, the output horn 16 may be rotated 125 by the actuator 30 alone, and the output shaft 102B is then restrained from rotating relative to the stator 51 and housing 54 via the no-back mechanism 100B, causing the motor 50 to act as a fixed coupling. Alternatively, if the actuator 30 fails and is no longer powered or inoperable 123 due to the no-back mechanism 100A, the output horn 16 may be rotated 125 by the actuator 50 alone, with the output shaft 102A then being restrained from rotating relative to the stator 31 and housing 34 via the no-back mechanism 100A, thereby causing the motor 30 to act as a fixed joint.

[0035] In the active-active scheme and normal mode 120, the controller 90 typically splits the position command equally between actuators 30 and 50 to perform control. After an actuator failure, the command to the remaining actuator is simply the position command. If any actuator stops in an off-center position, the command to the remaining actuator is biased to sweep or cancel the off-center input of the failed actuator.

[0036] Alternatively, in normal mode 120, only one of actuators 30 and 50 may be used to rotate output horn 16 and flight control output 20 relative to frame 19 during normal operation, referred to as an active-standby scheme, in which a single actuator provides full capability control until it fails and becomes inoperable, at which point the other actuator is activated to resume control while maintaining full capability.

[0037] A resolver 35 or another type of position sensor is configured to sense the position of the rotor 32 relative to the housing 34 and the stator 31. The resolver 35 is provided to adjust the position of the rotor 32 based on input commands from the controller 90. A resolver 55 or another type of position sensor is provided to sense the position of the rotor 52 relative to the housing 54 and the stator 51. The resolver 55 is provided to adjust the position of the rotor 52 based on input commands from the controller 90. A resolver 22 or another type of position sensor is provided to sense the position of the output horn 16 relative to the frame 19. The position sensor may be any electrical device for measuring position, or a derivative of position, or distance from an object, examples of which include an encoder, resolver, potentiometer, Hall effect sensor, linear variable differential transformer, varistor, variable capacitor, laser range finder, ultrasonic range detector, infrared range detector, or other similar device.

[0038] The controller 90 receives input commands from the pilot interface 95 and continuously compares the resolver position to the monitor 122 for mechanical faults. The system 15 includes diagnostic feedback to the controller 90 as a result. The controller 90 monitors data integrity, monitors the state of the sensor devices, monitors the power supply, and sets faults if parameters of interest fall outside acceptable levels. The controller 90 includes data sampling and storage mechanisms for receiving and storing sensor data, and data storage for storing logs of operational parameters and sensor data. The controller 90 is configured to perform various computer-implemented functions, such as performing method steps, calculations, and the like, as disclosed herein, and storing associated data. To communicate with the various sensors, the sensor interface allows signals transmitted by the sensors to be translated into signals that the processor 90 can understand and process. The sensors may be coupled to the sensor interface via a wired connection. In other embodiments, they may be coupled to the sensor interface via a wireless connection. In this embodiment, the controller 90 is a field programmable gate array ("FPGA"). However, a programmable logic device ("PLD"), microprocessor, microcontroller, or other similar device may be used instead. The controller may be any digital device having output lines that are a logical function of its input lines, including, for example, a microprocessor, microcontroller, field programmable gate array, programmable logic device, application specific integrated circuit, or other similar device. The controller 90 has inputs for receiving corresponding output signals from the sensors. The controller 90 is programmed to operate as disclosed herein and as shown in Figures 10, 11, 14, and 15.

[0039] Additionally, as shown in Figures 10 and 14, a redundant processor 90A and a processor 90B for modeling purposes may be provided. Redundant power supplies 96A and 96B may also be utilized. Motor drives 91A and 91B include drive power output electronics for commutating motors 30 and 50, respectively, and correspondingly receive feedback from sensors within the system and control motors 30 and 50.

[0040] As also shown in Figures 2, 3 and 9, a rotation stop 60 is provided to limit the range of rotation about axis 18 of housing 54 relative to housing 34 and frame 19. In this embodiment, stop 60 provides an angular limit of less than 120 degrees. A rotation stop 23 is provided to limit the range of rotation about axis 18 of output horn 23 relative to frame 19. In this embodiment, stop 23 provides a limit of angular range 21 that is less than 60 degrees. This allows for a simplified control scheme and electrical cabling to the actuators without the use of slip rings for signal commutation.

[0041] In this manner, system 15 pairs the rotary actuators together to provide maximum redundant fail-safe operation. Conventional multiple actuator systems have employed summing linkages or gearboxes, which are more complex and provide undesirable characteristics. Summing linkages and gearboxes require more parts and larger size enclosures and weight. Such conventional systems exhibit undesirable characteristics following failure of one of the actuators, exhibiting reduced reliability and safety due to the higher parts count and the introduction of failure modes that cannot be adequately mitigated.

[0042] FIG. 12 is a schematic diagram of a three-motor embodiment 115, which provides triple redundancy. This embodiment is similar to the system 15 described above in relation to actuators 30 and 50. However, in this embodiment, a third actuator 70 is provided between the rotor 52, and in particular the output gear shaft 59 of the gear mechanism 58, and the output horn 16. In this embodiment, the output gear shaft 59 of the gear mechanism 58 of the motor 50 is rigidly connected to the housing 74 of the motor 70. The housing 74 is rotationally supported by the aircraft frame 19 such that the housing 74 rotates about the axis 18 with the rotation of the output shaft 59 of the gear mechanism 58, which is rotationally coupled to the rotor 52 of the motor 50. When the rotor 52 of the motor 50 is not rotating relative to the housing 54 and / or the no-back device 100B is in the locked position, the housing 74 does not rotate relative to the motor housing 54. When the no-back device 100B is in the unlocked position, the housing 74 rotates about axis 18 relative to the motor housing 54 as a function of the coupling ratio between the rotor 52 and the output gear shaft 59 of the gear mechanism 58, accompanied by rotation of the rotor 52 relative to the motor housing 54.

[0043] The actuator 70 is supported within a housing 74 and includes a stator 71 and a rotor 72. The stator 71 is fixed to the housing 74, and the rotor 72 is driven to rotate relative to the housing 74 and the stator 71 about a central axis 18. In this embodiment, the actuator 70 is a brushless DC permanent magnet electric motor having an unpowered no-back device 100C and a planetary gear unit 78. The rotary motor 70 includes an outer non-rotating stator 71 with coil windings and an inner rotor 72 with permanent magnets 76. The stator 71 is fixed to the motor housing 74 so that the stator 71 does not rotate relative to the housing 74. When current is appropriately applied to the coils of the stator 71 via the drive unit 91C, a magnetic field is induced. The interaction of the magnetic fields between the stator 71 and the rotor 72 produces a torque that can rotate the shaft 101C. Drive electronics 91C generates and commutates a stator magnetic field based on the angular position feedback of resolver 75 to vary the speed and direction of motor 70. In response, motor 70 selectively applies torque to rotor 72 in either direction about axis 18 at various speeds. This drives rotor 72 to selectively rotate about axis of rotation 73 relative to stator 71 and housing 74.

[0044] The rotor 72 is rotationally coupled to a no-back input shaft 101C of the no-back device 100C. The no-back device 100C is substantially identical in configuration to the no-back device 100A. Thus, in the absence of driving torque from the motor 70 and rotor 72 to the input shaft 101C, the output shaft 102C is prevented from rotating by a spring 105 which effectively grounds the output shaft 102C to the housing 74 via a plate 104 and a lock pin 106. When torque is applied to the input shaft 101C from the rotor 72, the spring 105 is compressed, the pin 106 is released from the housing 74, and the output shaft 102C is engaged, allowing power to be transmitted from the input shaft 101C to the output shaft 102C.

[0045] The output shaft 102C of the no-back device 100C is in turn rotationally coupled to a gear transmission 78. The gear transmission 78 is of substantially the same configuration as the gear transmission 38. In this embodiment, the input to output ratio of the gear box 78 is greater than 1, and preferably is at least 120:1.

[0046] Other rotary motors or actuators, such as stepper motors, brush motors, induction motors, rotary hydraulic actuators, or the like, may alternatively be used. Also, other no-back devices, including but not limited to powered no-back devices, may alternatively be used. Additionally, other gear transmissions, or rotary couplings, such as belt couplings or other similar couplings, may be used to achieve the desired gear or speed ratios, or alternatively, no gears may be used.

[0047] In this embodiment 115, the output gear shaft 79 of the gear mechanism 78 is in turn rigidly connected to the output horn 16. The output horn 16 is rotationally supported by the aircraft frame 19 such that the output horn 16 rotates about axis 18 with rotation of the output shaft 79 of the gear mechanism 78, which is rotationally coupled to the rotor 72 of the motor 70. When the rotor 72 of the motor 70 is not rotating relative to the motor housing 74 and / or the no-back device 100C is in a locked position, the output horn 16 does not rotate relative to the housing 74. When the no-back device 100C is in an unlocked position, the output horn 16 rotates about axis 18 relative to the housing 74 with rotation of the rotor 72 relative to the motor housing 74 as a function of the coupling ratio between the rotor 72 and the output gear shaft 79 of the gear mechanism 78.

[0048] 14 and 15, controller 90 is connected to motor drives 91A, 91B, and 91C and monitors 222 actuators 30, 50, and 70 and provides commands to actuators 30, 50, and 70 to move output horn 16 to a desired position by controlling the corresponding rotation of rotor 32 relative to stator 31 and motor housing 34, rotation of rotor 52 relative to stator 51 and motor housing 54, and rotation of rotor 72 relative to stator 71 and motor housing 74. In normal mode 220, actuators 30, 50, and 70 are controlled to rotate output horn 16 and move flight control output 20 via linkage 25 as a function of the sum of the rotation of rotor 32, rotor 52, and rotor 72 relative to frame 19. However, in motor failure mode 221, any one or two of actuators 30, 50, and 70 may be controlled to rotate output horn 16 and flight control output 20 as a function of the rotation of rotors 32, 52, and 72 relative to frame 19 when one or two other of actuators 30, 50, or 70 fail. Thus, actuators 30, 50, and 70 have the characteristic that they cannot be back-driven following failure of the actuator in question, and the system provides maximum flight control performance during the occurrence of an actuator failure.

[0049] During normal operation 220, and in an active-active-active scheme, all of the actuators 30, 50, and 70 are used to rotate the output horn 16 and flight control output 20 relative to the frame 19. This is the preferred operation scheme in normal operation 120. However, if actuator 70 fails and is no longer powered or operable 225 due to the no-back mechanism 100C, the output horn 16 may be rotated 121 by actuators 30 and 50 as dual actuator 120 in dual actuator mode, with the output shaft 102C being restrained from rotating relative to the stator 71 and housing 74 via the no-back mechanism 100C, and the motor 70 thereby operating as a fixed joint. Alternatively, if the actuator 50 fails and is no longer powered or inoperable 224 due to the no-back mechanism 100B, the output horn 16 may be rotated 121 by the actuators 30 and 70 as dual actuators 120 in a dual actuator mode, with the output shaft 102B restrained from rotating relative to the stator 51 and housing 54 via the no-back mechanism 100B, and the motor 50 thereby operating as a fixed joint. In yet another alternative, if the actuator 30 fails and is no longer powered or inoperable 223 due to the no-back mechanism 100A, the output horn 16 may be rotated 121 by the actuators 50 and 70 as dual actuators 120 in a dual actuator mode, with the output shaft 102A restrained from rotating relative to the stator 31 and housing 34 via the no-back mechanism 100A, and the motor 30 thereby operating as a fixed joint.

[0050] If one of the actuators 30, 50, and 70 fails and is no longer powered or inoperable 223, 224, or 225, or a second of the actuators 30, 50, and 70 fails and is no longer powered or inoperable 123, 124, due to the no-back mechanism 100A, 100B, 100C respectively, the output horn 16 can be rotated by the remaining single actuator 30, 50, or 70 alone 125, with the failed motor thereby acting as a fixed coupling.

[0051] In the active-active-active scheme and normal mode 120, the controller 90 normally splits the position command equally between the actuators 30, 50, and 70 which it controls. After an actuator failure, the controller 90 normally splits the position command equally between the remaining two actuators which it controls. After a second actuator failure, the command to the remaining actuator is simply the position command. If any actuator stops in a non-center position, the command to the remaining actuator or actuators is biased to sweep or cancel the non-center input of the failed actuator or actuators.

[0052] Alternatively, in normal mode 120, only one of actuators 30, 50, and 70 may be used to rotate output horn 16 and flight control output 20 relative to frame 19 during normal operation, referred to as an active-standby-standby scheme. In this active-standby-standby scheme, a single actuator, such as actuator 30, provides full capacity control until it fails and becomes inoperable. When this occurs, an active-standby mode is utilized in which only one of the two remaining actuators, such as actuator 50, provides full capacity control until it fails and becomes inoperable. When this occurs, the other actuator, such as actuator 70, is activated to resume control while maintaining full capacity.

[0053] A resolver 75 is provided to sense the position of rotor 72 relative to housing 74 and stator 71. Resolver 75 is provided to adjust the position of rotor 72 based on input commands from controller 90. Controller 90 receives input commands from pilot interface 95 and continuously compares resolver position to monitor 222 for mechanical faults. System 115 thus includes diagnostic feedback to controller 90. Motor drives 91A, 91B, and 91C include drive power output electronics for commutating motors 30, 50, and 70, respectively, and receive corresponding feedback from sensors within the system and control motors 30, 50, and 70.

[0054] As also shown in FIG. 12, a rotation stop 60 is provided to limit the range of rotation about axis 18 of housing 54 relative to housing 34 and frame 19. In this embodiment, stop 60 provides an angular limit of 120 degrees or less. A rotation stop 80 is provided to limit the range of rotation about axis 18 of housing 74 relative to housing 54 and frame 19. In this embodiment, stop 80 provides an angular limit of 240 degrees or less. A rotation stop 23 is provided to limit the range of rotation about axis 18 of output horn 23 relative to frame 19. In this embodiment, stop 23 provides an angular limit of 60 degrees or less. This allows for a simplified control scheme and electrical cabling to the actuators without slip rings for signal commutation. This also allows the system to provide full speed movement of the full angular range of output horn 16 even with only one actuator operating at a time.

[0055] Frame 19 includes a number of bearings to provide rotational engagement with motor housings 54 and 74 and output horn 16. In this embodiment, rotary motors 30, 50, and 70 are mounted with their drive shafts coaxial and aligned about central axis 18. No-back mechanisms 100A, 100B, 100C, gear transmissions 38, 58, and 78, and output horn 16 are also aligned about central axis 18.

[0056] As noted above, actuator system 115 provides triple redundancy and fault or jam tolerance, which is extremely important in this and other aviation applications. Systems 15 and 115 provide continued power and output motion to the redundant actuation systems even after an internal mechanical failure that would cause other systems to jam or lock up the output.

[0057] Several modifications can be made to the disclosed embodiments. For example, but not by way of limitation, additional actuators oriented about the same central axis and having the functionality described above may be added to the system to provide further redundancy. Position sensors, resolvers, and / or encoders may also be added to the actuators and / or any other linkages to provide redundancy and provide useful feedback to the controller. Additional torque sensors, position sensors, and / or tachometers may also be added to each actuator output and / or any other linkage junctions in the linkage system 25 to provide further feedback.

[0058] Thus, while a presently preferred form of the actuator system has been shown and described, and several modifications have been discussed, those skilled in the art will readily appreciate that various additional changes could be made without departing from the scope of the invention.

Claims

1. an output member configured to selectively rotate relative to the structure about a rotational output axis and configured to impart motion to a driven body; a first secondary actuator having a first stator and a first rotor, a first secondary actuator, the first stator being fixed to the structure and the first rotor being configured to selectively rotate relative to the first stator about a first secondary axis of rotation; a second secondary actuator having a second stator and a second rotor, the second rotor is configured to selectively rotate relative to the second stator about a second secondary axis of rotation; the second stator is connected to the first rotor such that the second stator rotates about the first secondary axis of rotation relative to the first stator with rotation of the first rotor about the first secondary axis of rotation relative to the first stator; a second sub-actuator, the second rotor being connected to the output member; and at least one control device configured to drive the first secondary actuator and the second secondary actuator to selectively control rotation of the output member about the rotational output shaft within an output angular range of rotational motion about the rotational output shaft, the controller is configured to, in a normal mode, drive the first secondary actuator and the second secondary actuator to selectively control the rotation of the output member about the rotational output shaft as a function of a sum of the amounts of rotation of the first rotor and the second rotor about the first secondary rotation shaft and the second secondary rotation shaft, respectively, relative to the structure within an output angular range of rotational motion; a controller configured to, in a failure mode, drive one of the first secondary actuator or the second secondary actuator to selectively control the rotation of the output member about the rotational output shaft within an output angular range of the rotational motion, when the other of the first secondary actuator or the second secondary actuator is malfunctioning; 1. A rotary actuator assembly comprising:

2. a third secondary actuator having a third stator and a third rotor, the third rotor is configured to selectively rotate relative to the third stator about a third secondary axis of rotation; the third stator is connected to the second rotor such that the third stator rotates about the second secondary axis of rotation relative to the second stator with rotation of the second rotor about the second secondary axis of rotation relative to the second stator; the third rotor includes a third sub-actuator connected to the output member between the second rotor and the output member. the controller is configured in the normal mode to drive the first secondary actuator, the second secondary actuator, and the third secondary actuator to selectively control the rotation of the output member about the rotational output shaft as a function of a sum of the amounts of rotation of the first rotor, the second rotor, and the third rotor about the first secondary rotation shaft, the second secondary rotation shaft, and the third secondary rotation shaft, respectively, relative to the structure within an output angular range of rotational motion; the controller is configured to, in the failure mode, drive at least one of the first secondary actuator, the second secondary actuator, or the third secondary actuator to selectively control the rotation of the output member about the rotational output shaft within an output angular range of the rotational motion, while another of the first secondary actuator, the second secondary actuator, or the third secondary actuator is malfunctioning; 2. The rotary actuator assembly of claim 1.

3. 2. The rotary actuator system of claim 1, wherein the first minor axis of rotation and the second minor axis of rotation are the same, and the first rotor and the second rotor are coaxial.

4. 3. The actuator system of claim 2, wherein the first minor axis of rotation, the second minor axis of rotation, and the third minor axis of rotation are the same, and the first rotor, the second rotor, and the third rotor are coaxial.

5. The rotary actuator system of claim 1 , wherein the first minor rotation shaft, the second minor rotation shaft, and the rotary output shaft are the same.

6. the first secondary actuator includes a no-back brake configured to selectively inhibit the first rotor from rotating in a back-drive rotational direction about the first secondary axis of rotation relative to the first stator due to malfunction of the first secondary actuator; the second secondary actuator includes a no-back brake configured to selectively inhibit the second rotor from rotating in a reverse drive rotational direction about the second secondary axis of rotation relative to the second stator due to malfunction of the second secondary actuator; 10. The rotary actuator system of claim 1.

7. 7. The rotary actuator system of claim 6, wherein the controller is configured to sense a malfunction of the first secondary actuator and in response, to stop driving the first secondary actuator, and the controller is configured to sense a malfunction of the second secondary actuator and in response, to stop driving the second secondary actuator.

8. a first secondary actuator comprising a first position sensor connected to the controller and configured to sense an angular position of the first rotor about the first secondary axis of rotation relative to the first stator; the second secondary actuator comprises a second position sensor connected to the controller and configured to sense an angular position of the second rotor about the second secondary axis of rotation relative to the second stator.

10. The rotary actuator system of claim 1.

9. 9. The rotary actuator system of claim 8, wherein the output member comprises an output position sensor connected to the controller and configured to sense an angular position of the output member about the rotary output axis relative to the structure.

10. 2. The rotary actuator system of claim 1, comprising a first gear mechanism between the first rotor and the second stator, and a second gear mechanism between the second rotor and the output member.

11. 11. The rotary actuator system of claim 10, wherein the first gear mechanism and the second gear mechanism each have an input to output ratio greater than one.

12. The rotary actuator system of claim 10 , wherein the first gear mechanism and the second gear mechanism each comprise a planetary gear.

13. 2. The rotary actuator system of claim 1 , further comprising a gear mechanism between the first rotor and the second stator, the first rotor providing an input to the gear mechanism and the second stator providing an output from the gear mechanism.

14. 2. The rotary actuator system of claim 1, wherein the second stator rotates about the first minor axis of rotation relative to the first stator at a rotational speed that differs with rotation of the first rotor about the first minor axis of rotation relative to the first stator from a rotational speed of the first rotor about the first minor axis of rotation relative to the first stator.

15. 15. The rotary actuator system of claim 14, wherein the rotational speed of the second stator about the first minor axis of rotation relative to the first stator differs from the rotational speed of the first rotor about the first minor axis of rotation relative to the first stator as a function of a coupling ratio between the second stator and the first rotor.

16. 2. The rotary actuator system of claim 1, wherein the output angular range of rotary motion is less than 360 degrees about the rotary output shaft.

17. 2. The rotary actuator system of claim 1, comprising a first mechanical stop that limits rotation of the second stator about the first minor axis of rotation relative to the first stator to a second stator angular limit value that is less than or equal to 360 degrees.

18. 20. The rotary actuator system of claim 17, wherein the second stator angular limit of the first mechanical stop is at least twice an output angular range of the rotational motion of the output member about the rotary output shaft.

19. 20. The rotary actuator system of claim 18, comprising a mechanical stop that limits the output member to an output angular range of the rotational motion of the output member about the rotary output axis.

20. a first mechanical stop that limits rotation of the second stator about the first minor axis of rotation relative to the first stator to a second stator angle limit that is less than 360 degrees; and a second mechanical stop that limits rotation of the third stator about the second minor axis of rotation relative to the first stator to a third stator angle limit that is less than 360 degrees; and 3. The rotary actuator system of claim 2, comprising:

21. the second stator angular limit of the first mechanical stop is at least twice an output angular range of the rotational motion of the output member about the rotary output shaft; the third stator angle limit of the second mechanical stop is at least twice the second stator angle limit of the first mechanical stop; 21. The rotary actuator system of claim 20.

22. 22. The rotary actuator system of claim 21, comprising a mechanical stop that limits the output member to an output angular range of the rotational motion of the output member about the rotary output axis.

23. 2. The rotary actuator system of claim 1 , wherein the first secondary actuator comprises a brushless DC permanent magnet motor configured to drive the first rotor relative to the first stator about the first secondary axis of rotation, and the second secondary actuator comprises a brushless DC permanent magnet motor configured to drive the second rotor relative to the second stator about the second secondary axis of rotation.

24. The rotary actuator system of claim 1 , wherein the driven body is selected from the group consisting of an aircraft flight control mechanism and an aircraft flight control surface.

25. 25. The rotary actuator system of claim 24, wherein the driven body comprises a flight control surface of the aircraft, the flight control surface of the aircraft being selected from the group consisting of elevators, rudder, ailerons, flaps, slats, stabilizers, and spoilers.

26. 25. The rotary actuator system of claim 24, wherein the driven object comprises a flight control surface of the aircraft, and the output member is connected to the flight control surface via a torque tube.

27. 25. The rotary actuator system of claim 24, wherein the driven body comprises a flight control mechanism of the aircraft, the flight control mechanism of the aircraft being selected from the group consisting of a helicopter main rotor, a helicopter tail rotor, a helicopter main rotor swashplate, and a helicopter tail rotor swashplate.

28. The rotary actuator system of claim 1 , wherein the malfunction comprises a mechanical jam, a failure of an electric motor, or a loss of power.

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