Rotary actuator with position sensor

Abstract

An exemplary rotary actuator includes: a housing having a chamber therein; an output shaft disposed in the chamber and configured to rotate within the housing when a fluid flow is provided within the housing; a cam coupled to the output shaft and configured for rotation with the output shaft; and a rotation sensor mounted to the housing, where the rotation sensor interacts with the cam such that the rotation sensor provides sensor information indicative of rotational positions of the cam and the output shaft.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 428,741, filed on November 30, 2022, and U.S. Provisional Application No. 63 / 495,589, filed on April 12, 2023, all of which are incorporated herein by reference in their entirety as if fully set forth in this specification. Background Art

[0003] Some rotary actuators involve the use of high-pressure fluid to induce rotation of an output shaft. Such rotary actuators can be exposed to high torque, thrust, and radial loads because they are designed to be part of the structural load path in most applications.

[0004] In some applications, it may be desirable to measure the rotational position of the output shaft of a rotary actuator. However, standard encoders and position sensors are not designed to withstand the loads experienced by rotary actuators. Therefore, such sensors cannot be placed in high-load environments without additional support structures and space to operate.

[0005] Therefore, it may be desirable to integrate the sensor into the pressure chamber of the rotary actuator to remove the sensor from external loads. However, exposing the sensor to high pressure levels (eg, 5000 pounds per square inch) can create additional barriers to the use of some sensors.

[0006] Therefore, it may be desirable to have a position sensor that is configured to accurately measure the rotational position of an output shaft of a rotary actuator regardless of operating pressures in the actuator, external conditions, or internal loads under which the rotary actuator operates. With respect to these and other considerations, the present disclosure is presented herein. Summary of the Invention

[0007] This disclosure describes implementations involving a rotary actuator with a position sensor.

[0008] In a first exemplary implementation, the present disclosure describes a rotary actuator comprising: a housing having a chamber therein; an output shaft disposed in the chamber and configured to rotate within the housing when a fluid flow is provided within the housing; a cam coupled to the output shaft and configured to rotate therewith; and a rotational sensor mounted to the housing, wherein the rotational sensor interacts with the cam such that the rotational sensor provides sensor information indicative of a rotational position of the cam and the output shaft.

[0009] In a second exemplary implementation, the present disclosure also describes a method of operating the rotary actuator of the first exemplary implementation.

[0010] The foregoing summary is illustrative only and is not intended to be limiting in any way. In addition to the illustrative aspects, implementations, and features described above, further aspects, implementations, and features will become apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The novel features which are believed to be characteristic of the illustrative examples are set forth in the appended claims. However, the illustrative examples, together with the preferred mode of use, further objects and description thereof, will be best understood by reference to the following detailed description of illustrative examples of the present disclosure when read in conjunction with the accompanying drawings.

[0012] Figure 1 A perspective view of a rotary actuator is shown according to an exemplary implementation.

[0013] Figure 2 According to an exemplary implementation, Figure 1 Side view of the rotary actuator.

[0014] Figure 3 According to an exemplary implementation, Figure 1 Front view of the rotary actuator.

[0015] Figure 4A A perspective view of a rotation sensor is shown according to an exemplary implementation.

[0016] Figure 4B According to an exemplary implementation, Figure 4A Top view of the rotation sensor.

[0017] Figure 4C According to an exemplary implementation, Figures 4A to 4B Cross-sectional view of a rotation sensor.

[0018] Figure 5 According to an exemplary implementation, Figures 1 to 3 Cross-sectional side view of a rotary actuator.

[0019] Figure 6 A perspective view of an end cap is shown according to an exemplary implementation.

[0020] Figure 7A According to an exemplary implementation, Figures 1 to 3 Cross-sectional front view of a rotary actuator when the follower of the rotary sensor is in the uppermost position.

[0021] Figure 7B According to an exemplary implementation, Figure 7A Detailed view of a cross section.

[0022] Figure 8A According to an exemplary implementation, Figures 1 to 3 Cross-sectional front view of a rotary actuator when the follower of the rotary sensor is in an intermediate rotational position.

[0023] Figure 8B According to an exemplary implementation, Figure 8A Detailed view of a cross section.

[0024] Figure 9A According to an exemplary implementation, Figures 1 to 3 A cross-sectional front view of the rotary actuator when the follower of the rotary sensor is in the lowest position.

[0025] Figure 9B According to an exemplary implementation, Figure 9A Detailed view of a cross section.

[0026] Figure 10 According to an exemplary implementation, Figures 1 to 3 Another cross-sectional side view of the rotary actuator.

[0027] Figure 11 A cross-sectional side view of a rotary actuator is shown according to an exemplary implementation.

[0028] Figure 12 is a flow chart of a method for operating a rotary actuator according to an exemplary implementation. DETAILED DESCRIPTION

[0029] A rotary sensor capable of operating within a pressure vessel of a rotary actuator is disclosed herein. The rotary sensor has a follower that interacts with (e.g., follows or tracks) a cam surface of an output shaft of the rotary actuator mounted within the pressure vessel, such that the rotational position of the output shaft corresponds to the linear position of the follower.

[0030] In some examples, a second rotational sensor can be used to compensate for any deformation or radial "play" due to manufacturing tolerances or radial loads that may displace internal components of the rotary actuator. For example, such a second sensor may have a corresponding follower that interacts with (e.g., follows or tracks) a circular surface that is concentric with the output shaft. Thus, any radial play in the output shaft can be detected by the corresponding follower and measured by the second rotational sensor. This measurement can be subtracted from the measurement of the first or main sensor, thereby providing a more accurate measurement of the rotational position of the output shaft.

[0031] Figure 1shows a perspective view of a rotary actuator 100 according to an exemplary implementation, Figure 2 shows a side view of the rotary actuator 100, and Figure 3 FIG. 1 shows a front view of the rotary actuator 100. Figures 1 to 3 are described together.

[0032] The rotary actuator 100 includes a housing 102. The housing 102 serves as a pressure vessel or housing for the rotary actuator 100.

[0033] The housing 102 may have a plurality of ports, such as a first port 104 and a second port 106 axially spaced from the first port 104 along the length of the housing 102. The first port 104 and the second port 106 are configured to receive and discharge fluid (e.g., hydraulic fluid or gas). As described below, fluid provided to the first port 104 or the second port 106 may cause rotation of an output shaft 108 disposed longitudinally within the housing 102. Thus, the housing 102 is configured as a pressure vessel that can be filled with high-pressure fluid, for example, fluid at a pressure level of up to 5,000 pounds per square inch (psi).

[0034] The rotary actuator 100 includes a rotary sensor 110 mounted to a housing 102. As described below, the rotary sensor 110 extends within a chamber of the housing 102 and has a follower or a driven member. In one exemplary implementation, the driven member can be exposed to the high-pressure fluid within the chamber. In another exemplary implementation, the driven member can be protected from the high-pressure fluid.

[0035] In some example implementations, the rotary actuator 100 can include another rotation sensor 112. The rotation sensor 112 is configured to provide a reference measurement that can be used to correct or adjust the measurement of the rotation sensor 110 to compensate for any deformation caused by manufacturing tolerances or radial loads. In these examples, the rotation sensor 110 can be considered a primary rotation sensor, while the rotation sensor 112 can be considered a secondary or reference rotation sensor.

[0036] The controller 114 can receive sensor information from the rotation sensor 110 to determine the rotational position of the output shaft 108, as described in more detail below. The controller 114 may include one or more processors or microprocessors and may include a data storage device (e.g., a memory, a transitory computer-readable medium, a non-transitory computer-readable medium, etc.). The data storage device may have stored thereon instructions that, when executed by one or more processors of the controller 114, cause the controller 114 to perform the operations described herein.

[0037] Controller 114 may also receive corresponding sensor information from rotation sensor 112 to adjust the rotational position of output shaft 108 determined based on the sensor information from rotation sensor 110 to compensate for manufacturing tolerances or radial loads, as described below. In other examples, the electronics of rotation sensor 110 or rotation sensor 112 may perform the operations of controller 114.

[0038] Figure 4A shows a perspective view of a rotation sensor 110 according to an exemplary implementation, Figure 4B shows a top view of the rotation sensor 110, and Figure 4C FIG. 1 shows a cross-sectional view of the rotation sensor 110. FIG. Figures 4A to 4C are described together.

[0039] The rotation sensor 110 includes an adapter 200. In an example, the adapter 200 may be configured as Figure 4A The adapter 200 has a hexagonal body as shown. As an example, the adapter 200 can be made of machined stainless steel. The adapter 200 includes external threads 202 (e.g., Society of Automotive Engineers (SAE)-4 male threads) formed at a distal end of the adapter 200 and configured to engage corresponding internal threads in the housing 102 of the rotary actuator 100 to mount the rotary sensor 110 to the rotary actuator 100.

[0040] The adapter 200 may also include internal threads 204 (eg, a female SAE-4 threaded connection) at the proximal end of the adapter 200, such as Figure 4C The adapter 200 is configured to serve as a guide for a follower 206 of the rotation sensor 110. The follower 206 may also be referred to as a follower and is configured to move in an oscillating linear motion within the rotation sensor 110, as described in more detail below.

[0041] In an example, the follower 206 may be formed from an injection molded thermoplastic material (e.g., ) In one example, the follower 206 can have a tip 207 at the distal end of the follower 206. As described below, the tip 207 is configured to contact a cam surface (e.g., a cam surface of the cam 402 described below).

[0042] In an example, the tip 207 can be configured as a spherical tip. In this example, by being configured with a spherical shape, the tip 207 can ensure smooth and consistent contact with the cam surface that it follows. The spherical tip can also allow the follower 206 to maintain a consistent point of contact with the cam surface, regardless of the orientation of the follower 206 or the position of the cam. This is because the sphere has the same curvature in all directions, which ensures that the point of contact between the follower 206 and the cam surface remains constant, regardless of any small changes in the orientation of the follower 206 or the position of the cam.

[0043] The follower 206 has a cavity at its proximal end, and the rotation sensor 110 includes a magnet 208 disposed in the cavity. As an example, the magnet 208 can be a rare earth magnet coupled to the follower 206 or held in a cavity of the follower 206 and configured to generate a magnetic field.

[0044] The rotation sensor 110 also includes a tube 210 configured as a magnetic tube for the rotation sensor 110. In one example, the tube 210 is a machined stainless steel component having external threads at its distal end (e.g., an SAE-4 male threaded connection) that are configured to engage the internal threads 204 of the adapter 200 to couple the tube 210 to the adapter 200. Figure 4C As shown, tube 210 has an open distal end through which follower 206 is disposed and a closed distal end such that tube 210 and adapter 200 form a longitudinal aperture 211 within which follower 206 can oscillate in a linear motion.

[0045] The rotation sensor 110 also includes a spring 212 (e.g., a steel spring) disposed in the longitudinal aperture 211. The spring 212 is compressed between an enlarged portion 213 (e.g., a larger diameter section) of the follower 206 and an internal shoulder formed in the tube 210, as shown. Figure 4C . With this configuration, the proximal end of spring 212 is fixed, while the distal end of spring 212 rests against enlarged portion 213 of follower 206, biasing follower 206 in the distal direction. In this manner, spring 212 ensures that tip 207 of follower 206 remains in contact with the surface that follower 206 follows during operation. Because enlarged portion 213 contacts internal shoulder 214 at the distal end of adapter 200, the travel of follower 206 in the distal direction is limited.

[0046] The rotation sensor 110 also includes an electronics module 216 mounted to the outer surface of the tube 210. The electronics module 216 may also be referred to as a "read head" and is configured with a generally cylindrical body that houses electronics that detect changes in the magnetic field as the follower 206 and magnet 208 move linearly and thereby determine the linear position of the follower 206.

[0047] For example, the electronics module 216 may include a printed circuit board (PCB) located within the mold frame, and such a PCB may have electronics configured to interpret the magnetic field generated by the magnet 208 to determine the linear position of the follower 206. The PCB mechanically supports and electrically connects electronic components (e.g., microprocessors, integrated circuits, capacitors, resistors, etc.) using conductive traces, pads, and other features etched from one or more layers of a copper laminate laminated to and / or between sheets of a non-conductive substrate. Components are typically soldered to the PCB to electrically connect and mechanically secure the components to the PCB.

[0048] In the example, magnet 208 serves as a magnetic target for electronic module 216, which is configured to measure changes in magnetic field strength. When follower 206 moves, magnet 208 moves with follower 206, and the magnetic field strength sensed or measured by electronic module 216 changes. The position of follower 206 to which magnet 208 is attached can be correlated with the magnetic field strength measured by electronic module 216. Specifically, the processor of electronic module 216 can receive magnetic field strength information when magnet 208 moves, and can then determine the position of follower 206 based on the magnetic field strength information.

[0049] In an example, the electronics module 216 has one or more coils that receive power and, in response, generate a magnetic field that can interact with the magnetic field of the magnet 208. As the follower 206 and the magnet 208 move, the magnetic field changes, and this change is sensed by the coils of the electronics module 216. The coils of the electronics module 216 can then generate one or more voltage signals indicative of the change in the magnetic field, which is correlated to the linear position of the follower 206.

[0050] In an example, the rotation sensor 110 can include a retaining ring 218 and a washer 220 that are mounted circumferentially around the tube 210 and are configured to axially retain the electronics module 216 relative to the tube 210. As an example, the retaining ring 218 can be a steel snap ring mounted in a groove formed at the proximal end of the tube 210. The washer 220 can be a stainless steel flat washer used in conjunction with the retaining ring 218 to axially retain the electronics module 216 to the tube 210.

[0051] In one example, the rotation sensor 110 can include a spring 222 interposed between the electronics module 216 and the tube 210. The spring 222 is depicted as a wave spring; however, other types of biasing devices can be used. The spring 222 is configured to bias the electronics module 216 in a proximal direction toward the retaining ring 218 and the washer 220 to secure the electronics module 216 in a specific, repeatable position relative to the follower 206, thereby compensating for manufacturing tolerances in the follower 206 or the electronics module 216.

[0052] The rotation sensor 110 also includes a first seal 226 (e.g., an elastomeric O-ring seal) disposed about an outer surface of the adapter 200. The first seal 226 is configured to seal a bore in the housing 102 of the rotary actuator 100 in which the rotation sensor 110 is disposed to prevent leakage from a fluid-filled cavity within the housing 102 to the environment external to the rotary actuator 100. The rotation sensor 110 may also include a second seal 228 disposed in an annular groove formed in the tube 210 to seal the connection between the adapter 200 and the tube 210, thereby rendering the longitudinal aperture 211 a pressure-tight chamber in which the follower 206 linearly reciprocates.

[0053] The follower 206 is configured to follow a cam profile within the rotary actuator 100. The cam profile provides a continuously varying radial surface position relative to the central rotational axis of the output shaft 108 of the rotary actuator 100, and thus the linear position of the follower 206 indicates the rotational position of the output shaft 108 of the rotary actuator 100.

[0054] Although the rotation sensors 110, 112 are described herein as contact sensors in which a follower (such as follower 206) contacts a cam surface, it is contemplated herein that non-contact sensors may be used. Such non-contact sensors may be configured to measure the position of a rotating component based on interaction with a cam surface without contacting the cam surface. For example, the rotation sensor may be an optical sensor probe having an optical disc that serves as a window for monitoring the cam surface within a chamber of the housing 102.

[0055] Such an optical sensor may include a light source that emits light through an optical disc. The optical sensor may also include a sensing element that receives light reflected from the cam surface and converts the light into an electronic signal. Specifically, the sensing element may measure the distance to the cam surface and subsequently convert the measurement into an electrical signal indicating the distance and, therefore, the rotational position of the cam.

[0056] Thus, the term "interacting with a cam surface" is used herein to encompass contacting the cam surface or not contacting the cam surface but being configured to determine the rotational position of the cam surface. Thus, although the following description describes the rotation sensors 110, 112 as contact sensors, it should be understood that non-contact sensors may alternatively be used.

[0057] Figure 5 A cross-sectional side view of a rotary actuator 100 is shown according to an exemplary implementation. Figure 5 The cutting plane of the cross-sectional view passes through Figure 3 A rotation sensor 110 is shown.

[0058] exist Figures 1 to 3 、 Figure 5 The rotary actuator 100 depicted in the exemplary implementation of is a screw-type rotary actuator as an example for illustration. The disclosed rotary sensor configuration and operation can be used with other types of fluid-based rotary actuators.

[0059] The housing 102 of the rotary actuator 100 is a generally cylindrical body having a longitudinal axis 300. The output shaft 108 of the rotary actuator 100 is coaxial with the housing 102 and is configured for rotation about the longitudinal axis 300.

[0060] The housing 102 has an inner ring 302 that projects radially inwardly within a cavity 304 within the housing 102. The inner ring 302 may be referred to as a ring gear and has helical splines that project radially inwardly within the cavity 304. For example, the inner ring 302 may be welded to the inner surface of the housing 102.

[0061] The rotary actuator 100 further includes an annular piston 306 (a hollow piston) mounted in the chamber 304 around the output shaft 108. In other words, the annular piston 306 surrounds the output shaft 108 and is radially interposed between the output shaft 108 and the inner surface of the housing 102. The annular piston 306 has a piston head 308 and a piston rod 310.

[0062] The annular piston 306 has external helical splines 312 that project radially outward from the piston rod 310 and are configured to engage with internal helical splines of the inner ring 302 of the housing 102. The annular piston 306 also has internal helical splines 314 that project radially inward into the longitudinal cavity of the annular piston 306 and are configured to engage with external helical splines formed in the output shaft 108.

[0063] Reference together Figures 1 to 2 、 Figure 5When fluid is provided to the first port 104 of the rotary actuator 100, the fluid flows into the chamber 304 and in the proximal axial direction (e.g., toward Figure 5 306) applies a fluid force to the annular piston 306. The fluid force causes the annular piston 306 to move longitudinally (along the longitudinal axis 300) in a proximal axial direction.

[0064] Due to the engagement of the external helical splines 312 of the annular piston 306 with the internal helical splines of the inner ring 302 (which is fixed), the annular piston 306 rotates as it linearly translates in the proximal direction. In addition, due to the engagement of the internal helical splines 314 of the annular piston 306 with the external helical splines of the output shaft 108, when the annular piston 306 linearly translates in the proximal direction and rotates, the output shaft 108 rotates with the annular piston 306 in the first rotational direction. As the annular piston 306 moves, fluid is expelled from the other side of the piston head 308 through the second port 106.

[0065] In contrast, when fluid is provided to the second port 106 of the rotary actuator 100, the fluid flows into the chamber 304 and in the distal axial direction (e.g., toward Figure 5 ) exerts a corresponding fluid force on the annular piston 306. The corresponding fluid force causes the annular piston 306 to move longitudinally in the distal axial direction.

[0066] Due to the engagement of the external helical splines 312 of the annular piston 306 with the internal helical splines of the inner ring 302 (which is fixed), the annular piston 306 rotates as it linearly translates. In addition, due to the engagement of the internal helical splines 314 of the annular piston 306 with the external helical splines of the output shaft 108, when the annular piston 306 linearly moves in the distal direction and rotates, the output shaft 108 rotates with the annular piston 306 in a second rotational direction (opposite to the first rotational direction). As the annular piston 306 moves, fluid is expelled from the other side of the piston head 308 through the first port 104.

[0067] The annular piston 306 has an external groove in the piston head 308 in which a seal 316 is disposed to seal against the inner surface of the housing 102. The annular piston 306 also has an internal groove in which a seal 318 is disposed to seal against the outer surface of the output shaft 108. The seals 316, 318 prevent leakage or cross-flow between chambers formed in the chamber 304 on either side of the piston head 308.

[0068] As such, reciprocating longitudinal movement of the annular piston 306 within the housing 102 in response to the selective application of fluid on either side of the annular piston 306 causes the output shaft 108 to rotate clockwise or counterclockwise relative to the housing 102. For example, the rotational speed of the output shaft 108 may depend on the pitch of the helical splines of the annular piston 306.

[0069] The rotary actuator 100 further includes an end cap 320 mounted at a distal end of the housing 102 and coupled to the output shaft 108 such that rotation of the output shaft 108 causes the end cap 320 to rotate therewith. The rotation sensor 110 is configured to detect the rotational position of the end cap 320 .

[0070] Figure 6 A perspective view of an end cap 320 according to an exemplary implementation is shown. The end cap 320 can be coupled to the output shaft 108 in various ways. For example, the end cap 320 can have internal threads 400 configured to engage corresponding external threads of the output shaft 108 to rotatably couple the end cap 320 to the output shaft 108. However, other arrangements (e.g., a key-and-keyway arrangement, a spline arrangement, a self-retaining taper arrangement) can be used.

[0071] The end cap 320 has a cam 402. Figure 5 As shown, the follower 206 of the rotation sensor 110 is configured to contact the outer surface of the cam 402. The follower 206 remains in contact with the cam 402 during rotation of the output shaft 108 and the end cap 320. However, as described above, if a non-contact sensor is used, the sensing element of such a sensor can interact with the cam 402 to determine its position without contact.

[0072] In one example, the cam 402 can be configured to be included as an eccentric cylindrical portion (e.g., a lobe) that is radially offset relative to the longitudinal axis 300 (the axis of rotation of the output shaft 108) to provide a continuously varying radial surface position relative to the longitudinal axis 300 during rotational movement of the output shaft 108 and the end cap 320. With this configuration, as the end cap 320 rotates, the rotational motion of the end cap 320 and the cam 402 is converted into reciprocating motion of the follower 206 of the rotation sensor 110.

[0073] The configuration of the cam 402 is described herein as an example for illustration only. Any configuration that provides a continuously varying radial surface position relative to the longitudinal rotational axis 300 of the output shaft 108 during rotation is contemplated herein. Furthermore, interaction with such a configuration can be contact-based interaction or contactless (e.g., via an optical signal).

[0074] In an example where the rotation sensor 112 (secondary reference sensor) is used, the end cap 320 may have a flange 404 (e.g., a protruding rim) that is concentric with the output shaft 108. As described in more detail below, the circular surface 405 of the flange 404 serves as a reference surface that enables more accurate measurements by the rotation sensor 110 (primary sensor).

[0075] Reference together Figure 4C 、 Figure 5 , spring 212 causes the follower 206 of the rotation sensor 110 (particularly its tip 207) to maintain contact with the cam 402 of the end cap 320. As the cam 402 rotates through its range of rotational motion, the linear position of the follower 206 continuously changes along with the outer surface of the cam 402 that it follows due to the continuously varying radial distance between the center of rotation of the output shaft 108 (the longitudinal axis 300) and the outer surface of the cam 402.

[0076] As such, the rotation sensor 110, and in particular the electronics module 216, can provide sensor information indicative of the linear position of the follower 206, which in turn is indicative of the rotational position of the output shaft 108. In other words, the rotational position of the cam 402 (and therefore the end cap 320 and the output shaft 108) can be derived from the linear position of the follower 206 determined by the electronics module 216.

[0077] Figure 7A shows a cross-sectional front view of the rotary actuator 100 according to an exemplary implementation with the follower 206 in the uppermost position, and Figure 7B Shown Figure 7A Detailed view of the cross section of the Figure 2 Marked in Figure 7A The cutting plane of the cross section. Figure 7B An enlarged view of the rotation sensor 110 and cam 402 is provided when the follower 206 is in the uppermost position.

[0078] As shown, the cam 402 has lobes 406, e.g., projections or protrusions on the surface of the cam 402 designed to push the follower 206. In other words, the lobes 406 are raised features that convert the rotational motion of the cam 402 into linear motion of the follower 206. The shape and size of the lobes 406 can determine the characteristics of the linear movement of the follower 206.

[0079] exist 7A to 7BIn the illustrated rotational position of the cam 402, the lobe 406 is in a rotational position that fully retracts the follower 206 within the rotation sensor 110. As such, the follower 206 and the magnet 208 are radially in their highest position relative to the center 408 of the output shaft 108 (i.e., relative to the longitudinal axis 300). In other words, the follower 206 and the magnet 208 have moved the furthest from the center 408 in a radially outward direction.

[0080] Figure 8A shows a cross-sectional front view of the rotary actuator 100 according to an exemplary implementation with the follower 206 in an intermediate rotational position, and Figure 8B Shown Figure 8A Detailed view of a cross section. Figure 8A The cutting plane of the cross section is Figure 7A The cutting plane of the cross section is the same and is Figure 2 Marked in. Figure 8B An enlarged view of the rotation sensor 110 and cam 402 is provided when the cam 402 is in a mid-rotational position (ie, when the follower 206 is in the middle of its travel).

[0081] exist Figures 8A to 8B In the illustrated mid-rotational position of the cam 402, the lobe 406 (e.g., the raised portion of the cam 402) has been positioned relative to its Figure 7A 402) so that the highest point of the lobe 406 no longer abuts the follower 206. Rather, a lesser-protruding portion (e.g., the return portion of the cam profile) now abuts the follower 206, and as the follower 206 follows the surface of the cam 402, the spring 212 of the rotation sensor 110 pushes the follower 206 downward into the cavity 304 within the housing 102. Thus, the follower 206 and the magnet 208 are in a mid-stroke position and have moved radially inward toward the center 408 of the output shaft 108 (i.e., relative to the longitudinal axis 300).

[0082] As the cam 402 continues to rotate, the follower 206 correspondingly moves linearly. The electronic module 216 determines the linear position of the follower 206, which is indicative of the rotational position of the cam 402 and the output shaft 108.

[0083] Figure 9A shows a cross-sectional front view of the rotary actuator 100 according to an exemplary implementation with the follower 206 in a lowermost position, and Figure 9B Shown Figure 9A Detailed view of a cross section. Figure 9A The cutting plane of the cross section is Figure 7A The cutting plane of the cross section is the same and is Figure 2 Mark in. Figure 9B An enlarged view of the rotation sensor 110 and cam 402 is provided when the follower 206 is in the lowermost position.

[0084] As shown, the cam 402 has been rotated further in the counterclockwise direction (e.g., relative to its Figure 7A The position in the housing 102 is rotated 180 degrees), and the cam 406 is now diametrically opposite the position of the follower 206. As such, the follower 206 extends downwardly into the chamber 304 within the housing 102.

[0085] exist Figures 9A to 9B In the illustrated rotational position of the cam 402, the follower 206 is fully extended within the rotation sensor 110. As such, the follower 206 and the magnet 208 are in their lowest position relative to the center 408 of the output shaft 108 (i.e., relative to the longitudinal axis 300). In other words, the follower 206 and the magnet 208 have moved closest to the center 408.

[0086] Figure 7A 、 Figure 8A 、 Figure 9A The three positions shown in FIG. 4 are provided as examples of positions that the follower 206 passes through. During rotation of the output shaft 108 and the cam 402 , the linear position of the follower 206 changes continuously as the follower 206 follows the outer surface of the cam 402 .

[0087] As an example for illustration, the rotation sensor 110 may be configured such that the total travel of the follower 206 (eg, the total travel of the follower 206 in 7A to 7B The highest position and Figures 9A to 9B The total axial movement between the lowest position and the lowest position) is approximately 0.18 inches, which corresponds to 180 degrees of rotation of the cam 402. The electronic module 216 can be configured to detect movement as small as one tenth of a thousandth of an inch (0.0001 inches). In this example, the electronic module 216 can determine the rotational position of the cam 402 and the output shaft 108 with an accuracy of 0.1 degrees.

[0088] In some examples, due to manufacturing tolerances, the assembly of the output shaft 108, annular piston 306, and end cap 320 may be offset relative to the center of the housing 102. As an example, there may be a gap (e.g., 0.005-0.008 inches) between the outer surface of the end cap 320 (and the outer surface of the piston head 308) and the inner surface of the housing 102. As such, there may be some radial "play" or movement in the assembly of the output shaft 108, annular piston 306, and end cap 320 within the chamber 304 of the housing 102.

[0089] In these examples, this radial play may cause the position of follower 206 to provide an inaccurate indication of the rotational position of output shaft 108. For example, if the assembly is shifted downward in chamber 304, follower 206 may extend into chamber 304, which may inaccurately or falsely indicate that cam 402 has rotated.

[0090] In another example, components of the rotary actuator 100 (such as the housing 102, the end cap 320, or the annular piston 306) may deform due to the high fluid pressure in the chamber 304 (e.g., pressure levels up to 5000 psi). For example, the inner surface of the housing 102 may not remain circular under high pressure. Such deformation may also affect the accuracy of the rotation sensor 110 in indicating the rotational position of the output shaft 108.

[0091] In these examples, it may be desirable to configure the rotary actuator 100 such that the rotation sensor 112 operates as a reference sensor that provides a baseline or reference value for the position of the internal components of the rotary actuator 100. Such a reference value can then be subtracted from the measurement of the rotation sensor 110 to eliminate the effects of any radial play or deformation.

[0092] like Figure 1 、 Figure 3 As shown, in one example, the rotation sensor 112 is angularly spaced from the rotation sensor 110 about the surface of the housing 102. For example, the rotation sensor 112 may be angularly spaced from the rotation sensor 110 by less than 30 degrees.

[0093] Additionally, the rotation sensor 112 is axially or longitudinally offset from the rotation sensor 110 along the length of the housing 102 , as shown. Figures 1 to 2 For example, the rotation sensor 112 may be axially offset from the rotation sensor 110 by a distance that is less than the diameter of the rotation sensor 110 or the electronics module 216 of the rotation sensor 112 .

[0094] Figure 10 Another cross-sectional side view of a rotary actuator 100 is shown according to an exemplary implementation. Figure 10 The cutting plane of the cross-sectional view passes through the rotation sensor 112, as shown in FIG. Figure 3 shown.

[0095] As described above, in addition to the cam 402, the end cap 320 also includes a flange 404 having a circular surface 405. The circular surface 405 is coaxial or concentric with the center of rotation (e.g., center 408) of the output shaft 108. As such, the circular surface 405 has a constant radius, and points on the circular surface 405 are equidistant from the center 408 of the output shaft 108.

[0096] The rotation sensor 112 can be configured similarly to the rotation sensor 110 and can have a follower 500 that contacts the circular surface 405. As such, the rotation sensor 112 can measure and provide corresponding sensor information indicative of the position of the circular surface 405, which is concentric with the output shaft 108. It should be understood that a non-contact sensor can alternatively be used.

[0097] Circular surface 405 provides a baseline surface for measurement via rotation sensor 112. This measurement can then be used to correct the measurement of rotation sensor 110 so that movement of cam 402 of end cap 320 caused by radial play or deformation is eliminated.

[0098] Specifically, in an example, the measurement or position of the circular surface 405 detected by the follower 500 of the rotation sensor 112 can be subtracted from the measurement of the position of the follower 206 of the rotation sensor 110 to eliminate any inaccuracies caused by unintended movement (e.g., radial play) of the end cap 320. Eliminating this extraneous radial motion (when the end cap 320 experiences radial deflection relative to the housing 102 due to component assembly play or under heavy external loads) can result in a more accurate and repeatable angular position resolution of the output shaft 108 determined by the rotation sensor 110.

[0099] Advantageously, as Figure 10 As shown, circular surface 405 is positioned in close proximity to cam 402. This proximity between cam 402, followed by follower 206 of rotation sensor 110, and circular surface 405, followed by follower 500 of rotation sensor 112, can allow for more accurate determination of the rotational position of output shaft 108 after any radial play or deformation has been eliminated. Specifically, having cam 402 in close proximity to circular surface 405 and having both cam 402 and circular surface 405 permanently fixed to end cap 320 allows for instantaneous subtraction of the output value of rotation sensor 110, eliminating any positional changes of end cap 320 relative to housing 102.

[0100] like Figure 5 、 Figure 10 As shown, the end cap 320 includes a first annular groove 502 adjacent the circular surface 405 and a second annular groove 504 axially spaced from the first annular groove 502. The rotary actuator 100 may include a bearing (e.g., a radial ball bearing or a bushing) disposed in the first annular groove 502 to facilitate rotation of the end cap 320 relative to the housing 102.

[0101] The rotary actuator 100 may further include a rotary pressure seal disposed in the second annular groove 504 to seal the pressure chamber within the housing 102 from the environment external to the rotary actuator 100. This rotary pressure seal may be configured to form a seal around the end cap 320 as the end cap 320 rotates. Figure 5 、 Figure 10 In the configuration shown, the rotary sensors 110, 112 are subjected to high pressure fluid when the rotary pressure seal in the second annular groove 504 is positioned away from the rotary sensors 110, 112. If it is desired not to subject the rotary sensors 110, 112 to high pressure fluid, the end caps can be reconfigured so that the rotary pressure seal is positioned proximal to the rotary sensors 110, 112.

[0102] Figure 11 A cross-sectional side view of a rotary actuator 600 according to an exemplary implementation is shown. The rotary actuator 600 is similar to the rotary actuator 100, and like components are indicated with like reference numerals.

[0103] The rotary actuator 600 includes an end cap 602 that differs from the end cap 320 in that the end cap 602 has a cam 604 (similar to the cam 402) and a circular surface 606 (similar to the circular surface 405) that are located distally of a first annular groove 608 in which the bearing is disposed and a second annular groove 610 in which the rotary pressure seal is disposed. With this configuration, the rotary pressure seal in the second annular groove 610 isolates the rotary sensors 110, 112 from the high-pressure fluid in the chamber 304.

[0104] Figure 12 700 is a flow chart of a method 700 for operating a rotary actuator 100, 600 according to an exemplary implementation. The method 700 may include one or more operations or actions as shown by one or more of blocks 702-708. Although the blocks are shown in sequence, in some cases, the blocks may be performed in parallel and / or in a different order than described herein. In addition, various blocks may be combined into fewer blocks, divided into additional blocks, and / or removed based on the desired implementation.

[0105] In addition, for the method 700 and other processes and operations disclosed herein, the flowchart illustrates the operation of one possible implementation of this example. In this regard, some boxes may represent a module, segment, or portion of a program code that includes one or more instructions that can be executed by a processor (e.g., the processor of the rotation sensor 110 or an external controller, such as the controller 114) to implement specific logical operations or steps in the process. The program code can be stored on any type of computer-readable medium or memory, for example, such as a storage device including a disk or hard drive. The computer-readable medium may include non-transitory computer-readable media or memory, for example, such as a computer-readable medium that stores data for a short period of time, such as register memory, processor cache, and random access memory (RAM). The computer-readable medium may also include non-transitory media or memory, such as auxiliary or persistent long-term storage devices, such as read-only memory (ROM), optical disks or disks, compact disk read-only memory (CD-ROM). The computer-readable medium may also be any other volatile or non-volatile storage system. For example, the computer-readable medium may be considered to be a computer-readable storage medium, a tangible storage device, or other article of manufacture. In addition, for the method 700 and other processes and operations disclosed herein, Figure 12 One or more blocks in the may represent circuits or digital logic arranged to perform the specific logical operations in the process.

[0106] At box 702, method 700 includes providing a fluid flow to a rotary actuator 100, wherein the rotary actuator 100 includes: (i) a housing 102 having a chamber 304 therein, (ii) an output shaft 108 disposed in the chamber 304, (iii) a cam 402, 604 coupled to the output shaft 108, and (iv) a rotation sensor 110 mounted to the housing 102 and including a follower 206 extending into the chamber 304 of the housing 102 to contact the cam 402, 604.

[0107] At block 704 , method 700 includes rotating the cams 402 , 604 with the output shaft 108 in response to providing fluid flow within the cavity 304 of the housing 102 of the rotary actuator 100 , such that rotation of the cams 402 , 604 causes linear movement of the follower 206 .

[0108] At block 706, the method 700 includes determining the linear position of the follower 206 based on the sensor information from the rotation sensor 110. For example, the electronics module 216 may determine the linear position of the follower 206 based on the sensor information, or the sensor information may be provided to an external controller (e.g., the controller 114), and such a controller determines the linear position.

[0109] At block 708 , the method 700 includes determining the rotational position of the cams 402 , 604 and the output shaft 108 based on the linear position of the follower.

[0110] The method 700 may also be any of the operations described herein. For example, the rotary actuator 100 may further include a circular surface 405 concentric with the output shaft 108, and the rotary sensor 112 may be mounted to the housing and include a follower 500 extending into the cavity 304 of the housing 102 to contact the circular surface 405. The method may include determining a corresponding linear position of the follower 500 based on corresponding sensor information from the rotary sensor 112, and adjusting the rotational position of the cam 402 and the output shaft 108 based on the corresponding linear position of the follower 500. For example, adjusting the rotational position of the cam 402 and the output shaft 108 may be based on subtracting the corresponding linear position of the follower 500 from the linear position of the follower 206.

[0111] The above detailed description describes various features and operations of the disclosed system with reference to the accompanying drawings. The illustrative embodiments described herein are not intended to be limiting. Certain aspects of the disclosed system can be arranged and combined in a variety of different configurations, all of which are contemplated herein.

[0112] Furthermore, unless the context indicates otherwise, the features shown in each figure may be used in combination with each other. Thus, the drawings should generally be viewed as component aspects of one or more overall embodiments, with it being understood that not all illustrated features are required for each embodiment.

[0113] In addition, any listing of elements, blocks, or steps in this patent specification or claims is for clarity purposes. Therefore, such listing should not be interpreted as requiring or implying that these elements, blocks, or steps follow a specific arrangement or are performed in a specific order.

[0114] Furthermore, a device or system may be used or configured to perform the functions shown in the figures. In some cases, components of a device and / or system may be configured to perform a function such that the component is physically configured and constructed (with hardware and / or software) to achieve such performance. In other examples, components of a device and / or system may be arranged to be modified to, capable of, or adapted to perform a function, such as when operated in a particular manner.

[0115] The terms "substantially" or "approximately" mean that the feature, parameter or value described need not be precisely achieved, but deviations or changes (including, for example, tolerances, measurement errors, measurement precision limitations and other factors known to those skilled in the art) may occur in amounts that do not negate the effect that the feature is intended to provide.

[0116] The arrangements described herein are for illustrative purposes only. Therefore, those skilled in the art will appreciate that other arrangements and other elements (e.g., machines, interfaces, operations, groupings of instructions and operations, etc.) may be used instead, and some elements may be omitted entirely depending on the desired results. Furthermore, many of the elements described are functional entities that may be implemented as discrete or distributed components or with other components in any suitable combination and location.

[0117] Although various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for illustrative purposes only and are not intended to be limiting, with the true scope being indicated by the appended claims and the full range of equivalents to which such claims are entitled. Furthermore, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0118] Therefore, embodiments of the present disclosure may be related to one of the Enumerated Example Embodiments (EEE) listed below.

[0119] EEE 1 is a rotary actuator comprising: a housing having a chamber therein; an output shaft disposed in the chamber and configured to rotate within the housing when a fluid flow is provided within the housing; a cam coupled to the output shaft and configured to rotate together with the output shaft; and a rotation sensor mounted to the housing, wherein the rotation sensor interacts with the cam such that the rotation sensor provides sensor information indicative of a rotational position of the cam and the output shaft.

[0120] EEE 2 is a rotary actuator according to EEE 1, wherein the rotation sensor includes a follower extending into the cavity of the housing to contact the cam and thereby follow the surface of the cam, so that rotation of the cam causes the follower to move linearly, wherein the rotation sensor is configured to provide sensor information indicating the linear position of the follower, thereby indicating the rotational position of the cam and the output shaft.

[0121] EEE 3 is a rotary actuator according to EEE 2, wherein the cam includes a lobe that is radially offset relative to the longitudinal axis of the output shaft so that when the output shaft rotates about the longitudinal axis, the surface of the cam followed by the follower has a continuously changing position relative to the longitudinal axis.

[0122] EEE 4 is a rotary actuator according to any one of EEEs 1 to 3, wherein the rotation sensor is a first rotation sensor, and the rotary actuator further includes: a circular surface concentric with the output shaft; and a second rotation sensor mounted to the housing, wherein the second rotation sensor interacts with the circular surface so that the second rotation sensor provides corresponding sensor information indicating the position of the circular surface, and the corresponding sensor information of the second rotation sensor is used to correct the sensor information of the first rotation sensor to determine the rotational position of the cam and the output shaft.

[0123] EEE 5 is a rotary actuator according to EEE 4, wherein: the first rotation sensor includes a first follower, which extends into the cavity of the housing to contact the cam and thus follow the surface of the cam, so that rotation of the cam causes the first follower to move linearly, wherein the rotation sensor is configured to provide sensor information indicating the linear position of the first follower, thereby indicating the rotational position of the cam and the output shaft, and the second rotation sensor includes a second follower, which extends into the cavity of the housing to contact the circular surface, wherein the corresponding sensor information indicates the corresponding linear position of the second follower, thereby indicating the position of the circular surface.

[0124] EEE 6 is a rotary actuator according to EEE 4 or 5, wherein the second rotation sensor is angularly spaced from the first rotation sensor around the surface of the housing.

[0125] EEE 7 is a rotary actuator according to any one of EEEs 4 to 6, wherein the second rotation sensor is axially offset relative to the first rotation sensor along the length of the housing.

[0126] EEE 8 is a rotary actuator according to any one of EEE 4 to 7, wherein the rotary actuator further comprises: an end cap mounted to the output shaft and configured to rotate with the output shaft, wherein the end cap comprises the cam and the circular surface such that the circular surface is adjacent to the cam.

[0127] EEE 9 is a rotary actuator according to any one of EEE 1 to 8, wherein the rotary actuator further comprises: an annular piston mounted to the output shaft so that the fluid provided in the chamber of the housing applies fluid force to the annular piston, causing the annular piston to move linearly in the chamber, thereby rotating the output shaft.

[0128] EEE 10 is a rotary actuator according to EEE 9, wherein the housing includes an inner ring having an internal helical spline, wherein the annular piston includes an external helical spline, and the external helical spline engages with the internal helical spline of the inner ring of the housing, so that linear movement of the annular piston causes the annular piston to rotate relative to the housing.

[0129] EEE 11 is a rotary actuator according to EEE 10, wherein the annular piston further comprises corresponding internal helical splines that engage corresponding external helical splines formed in the output shaft, such that rotation of the annular piston causes the output shaft to rotate relative to the housing.

[0130] EEE 12 is a rotary actuator according to EEE 11, wherein the rotary actuator further comprises: a first port formed in the housing; and a second port formed in the housing, the second port being axially spaced apart from the first port along the length of the housing, wherein supplying fluid to the chamber through the first port causes the annular piston to move in a first axial direction, so as to cause the output shaft to rotate in a first rotational direction, and supplying fluid to the chamber through the second port causes the annular piston to move in a second axial direction, so as to cause the output shaft to rotate in a second rotational direction opposite to the first rotational direction.

[0131] EEE 13 is a rotary actuator according to any one of EEE 1 to 12, wherein the rotary actuator further comprises: an end cover mounted to the output shaft and configured to rotate with the output shaft, wherein the end cover comprises: (i) the cam, (ii) a first annular groove, a bearing is disposed in the first annular groove to facilitate rotation of the end cover, and (iii) a second annular groove, a rotary pressure seal is disposed in the second annular groove.

[0132] EEE 14 is a rotary actuator according to EEE 13, wherein the rotary pressure seal is disposed distally of the rotary sensor so that the rotary sensor is subjected to high-pressure fluid in the cavity of the housing.

[0133] EEE 15 is a rotary actuator according to EEE 13, wherein the rotary pressure seal is disposed proximal to the rotary sensor so that the rotary sensor is isolated from the high-pressure fluid in the cavity of the housing.

[0134] EEE 16 is a rotary actuator according to any one of EEE 1 to 15, wherein the rotary sensor includes: an adapter configured to facilitate mounting the rotary sensor to the housing; a follower extending into the chamber of the housing to contact the cam and thereby follow the surface of the cam; and a tube coupled to the adapter and forming a longitudinal aperture with the adapter such that when the cam rotates, the follower oscillates linearly in the longitudinal aperture.

[0135] EEE 17 is a rotary actuator according to EEE 16, wherein the rotation sensor further comprises: a spring installed in the longitudinal aperture and configured to bias the follower toward the cam to maintain contact between the follower and the cam when the cam rotates with the output shaft.

[0136] EEE 18 is a rotary actuator according to EEE 16 or 17, wherein the rotary sensor includes: a magnet mounted to the follower and capable of moving with the follower; and an electronic module mounted to the tube and configured to detect the linear position of the follower and the magnet.

[0137] EEE 19 is a rotary actuator according to EEE 18, wherein the rotary sensor includes: a retaining ring, which is mounted to the tube and axially retains the electronic module to the tube; and a spring, which is inserted between the tube and the electronic module and applies a biasing force toward the retaining ring to the electronic module to fix the electronic module in a specific position relative to the follower.

[0138] EEE 20 is a method for operating a rotary actuator according to any one of EEEs 1 to 19. For example, the method includes: providing a fluid flow to a rotary actuator, wherein the rotary actuator includes: (i) a housing having a chamber therein, (ii) an output shaft disposed in the chamber, (iii) a cam coupled to the output shaft, and (iv) a rotation sensor, the rotation sensor being mounted to the housing and including a follower extending into the chamber of the housing to contact the cam; in response to providing the fluid flow within the chamber of the housing of the rotary actuator, rotating the output shaft, thereby causing the cam to rotate together with the output shaft, such that the rotation of the cam causes the follower to move linearly; determining a linear position of the follower based on sensor information from the rotation sensor; and determining a rotational position of the cam and the output shaft based on the linear position of the follower.

Claims

1. A rotary actuator comprising: a housing having a chamber therein; an output shaft disposed in the chamber and configured to rotate within the housing when providing fluid flow within the housing; a cam coupled to the output shaft and configured for rotation therewith; as well as A rotation sensor is mounted to the housing, wherein the rotation sensor interacts with the cam such that the rotation sensor provides sensor information indicative of a rotational position of the cam and the output shaft.

2. The rotary actuator according to claim 1, wherein: The rotation sensor includes a follower extending into the cavity of the housing to contact the cam and thereby follow the surface of the cam, so that rotation of the cam causes the follower to move linearly, wherein the rotation sensor is configured to provide sensor information indicative of the linear position of the follower, thereby indicating the rotational position of the cam and the output shaft.

3. The rotary actuator according to claim 2, wherein: The cam includes a lobe that is radially offset relative to a longitudinal axis of the output shaft such that the surface of the cam followed by the follower has a continuously changing position relative to the longitudinal axis as the output shaft rotates about the longitudinal axis.

4. The rotary actuator according to claim 1, wherein: The rotation sensor is a first rotation sensor, and the rotation actuator further comprises: a circular surface concentric with the output shaft; and a second rotation sensor mounted to the housing, wherein the second rotation sensor interacts with the circular surface such that the second rotation sensor provides corresponding sensor information indicative of a position of the circular surface, and the corresponding sensor information of the second rotation sensor is used to correct the sensor information of the first rotation sensor to determine the rotational position of the cam and the output shaft.

5. The rotary actuator according to claim 4, wherein: the first rotation sensor includes a first follower extending into the cavity of the housing to contact the cam to follow a surface of the cam such that rotation of the cam causes linear movement of the first follower, wherein the rotation sensor is configured to provide sensor information indicative of a linear position of the first follower, thereby indicating the rotational position of the cam and the output shaft, and The second rotation sensor includes a second follower extending into the cavity of the housing to contact the circular surface, wherein the corresponding sensor information indicates a corresponding linear position of the second follower, thereby indicating the position of the circular surface.

6. The rotary actuator according to claim 4, wherein: The second rotation sensor is angularly spaced from the first rotation sensor about a surface of the housing.

7. The rotary actuator according to claim 4, wherein: The second rotation sensor is axially offset relative to the first rotation sensor along a length of the housing.

8. The rotary actuator according to claim 4, wherein: The rotary actuator further comprises: An end cap is mounted to the output shaft and is configured for rotation therewith, wherein the end cap includes the cam and the circular surface such that the circular surface is adjacent the cam.

9. The rotary actuator according to claim 1, wherein: The rotary actuator further comprises: An annular piston is mounted to the output shaft such that fluid provided within the chamber of the housing applies a fluid force to the annular piston, causing the annular piston to move linearly within the chamber, thereby rotating the output shaft.

10. The rotary actuator according to claim 9, wherein: The housing includes an inner ring having internal helical splines, wherein the annular piston includes external helical splines that engage the internal helical splines of the inner ring of the housing such that linear movement of the annular piston causes the annular piston to rotate relative to the housing.

11. The rotary actuator according to claim 10, wherein: The annular piston also includes corresponding internal helical splines that engage corresponding external helical splines formed in the output shaft such that rotation of the annular piston causes the output shaft to rotate relative to the housing.

12. The rotary actuator according to claim 11, wherein: The rotary actuator further comprises: a first port formed in the housing; and a second port formed in the housing, the second port axially spaced from the first port along a length of the housing, wherein providing fluid to the chamber through the first port causes the annular piston to move in a first axial direction to cause the output shaft to rotate in a first rotational direction, and providing fluid to the chamber through the second port causes the annular piston to move in a second axial direction to cause the output shaft to rotate in a second rotational direction opposite the first rotational direction.

13. The rotary actuator according to claim 1, wherein: The rotary actuator further comprises: an end cover mounted to the output shaft and configured to rotate with the output shaft, wherein the end cover comprises: (i) the cam, (ii) a first annular groove in which a bearing is disposed to facilitate rotation of the end cover, and (iii) a second annular groove in which a rotary pressure seal is disposed.

14. The rotary actuator according to claim 13, wherein: The rotary pressure seal is disposed distally of the rotary sensor such that the rotary sensor is subjected to high pressure fluid in the cavity of the housing.

15. The rotary actuator according to claim 13, wherein: The rotation pressure seal is disposed proximal to the rotation sensor such that the rotation sensor is isolated from high-pressure fluid in the cavity of the housing.

16. The rotary actuator according to claim 1, wherein: The rotation sensor comprises: an adapter configured to facilitate mounting the rotation sensor to the housing; a follower extending into the cavity of the housing to contact the cam to follow a surface of the cam; and A tube is coupled to the adapter and forms a longitudinal aperture with the adapter such that when the cam rotates, the follower oscillates linearly in the longitudinal aperture.

17. The rotary actuator according to claim 16, wherein: The rotation sensor further includes: A spring is mounted in the longitudinal bore and is configured to bias the follower toward the cam to maintain contact between the follower and the cam when the cam rotates with the output shaft.

18. The rotary actuator according to claim 16, wherein: The rotation sensor comprises: a magnet mounted to the follower and movable with the follower; and An electronics module is mounted to the tube and is configured to detect the linear position of the follower and the magnet.

19. The rotary actuator according to claim 18, wherein: The rotation sensor comprises: a retaining ring mounted to the tube and retaining the electronics module axially to the tube; and A spring is interposed between the tube and the electronic module and applies a biasing force to the electronic module toward the retaining ring to fix the electronic module in a specific position relative to the follower.

20. A method comprising: providing a fluid flow to a rotary actuator, wherein the rotary actuator includes: (i) a housing having a chamber therein, (ii) an output shaft disposed in the chamber, (iii) a cam coupled to the output shaft, and (iv) a rotation sensor mounted to the housing and including a follower extending into the chamber of the housing to contact the cam; in response to providing a fluid flow within the chamber of the housing of the rotary actuator, rotating the output shaft to cause the cam to rotate with the output shaft such that rotation of the cam causes linear movement of the follower; determining a linear position of the follower based on sensor information from the rotation sensor; and The rotational position of the cam and the output shaft is determined based on the linear position of the follower.

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