System and method for fine pointing of payload

Abstract

To provide systems and methods which enable a pivot point of reflector movement to be close to a source and reflector focal point.SOLUTION: A two-axis pointing system includes: a first rotary actuator 140 which controls movement of a payload, which may be an antenna reflector 102, along a first actuator axis by moving a first connecting rod 144; a second rotary actuator 150 which controls movement of the payload along a second actuator axis; and a first strut 110-1, a second strut 110-2 and a third strut 110-3, where each strut is movably connected to the payload at a first end and movably connected to a base 160 at a second end, and restricts movement of the payload, caused by the first rotary actuator 140 and the second rotary actuator 150, to rotation around a virtual pivot point 108.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The following relates generally to payload pointing mechanisms, and more particularly to systems and methods for two-axis pointing of payloads, such as antenna reflectors. [Background technology]

[0002] In conventional antenna pointing mechanisms, when a reflector is steered relative to a fixed signal source (or signal receiver), the signal (eg, radio frequency) is degraded due to defocusing and / or mispointing.

[0003] To minimize signal degradation, the focal point of the reflector, which is moved by the pointing mechanism, needs to remain as close to the source (or receiver) as possible. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 9,172,154 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, there is a need in the art for improved systems and methods that allow the pivot point of the reflector's movement to be closer to the source and the reflector's focal point to overcome at least some of the shortcomings of existing systems and methods. [Means for solving the problem]

[0006] Provided herein is a two-axis pointing system for pointing a payload, the system comprising: a payload; a first actuator connected to the payload by at least a first connecting rod, the first actuator controlling movement of the payload along a first actuator axis by moving the first connecting rod; a second actuator connected to the payload by a second connecting rod, the second actuator controlling movement of the payload along the second actuator axis by moving the second connecting rod; and a first strut, a second strut, and a third strut, each strut movably connected to the payload at a first end and to a base at a second end opposite the first end, the first strut, and the third strut constraining movement of the payload caused by the first actuator and the second actuator to rotation about a virtual pivot point.

[0007] In one embodiment, the first strut has a first strut axis along the length of the first strut, the second strut has a second strut axis along the length of the second strut, and the third strut has a third strut axis along the length of the third strut, and an extrapolation of the first strut axis, the second strut axis, and the third strut axis intersect at a virtual pivot point of the payload when the payload is centered midway through the payload's pointing range.

[0008] The payload may be an antenna reflector.

[0009] The payload may have a focal point and the virtual pivot point may be approximately at the focal point.

[0010] The first actuator axis and the second actuator axis may be orthogonal.

[0011] The first actuator and the second actuator may be each one of a rotary actuator and a linear actuator.

[0012] Each of the first strut, the second strut, and the third strut may be connected to the payload by a spherical bearing.

[0013] Each of the first strut, the second strut, and the third strut may be connected to the payload support structure by a spherical bearing.

[0014] Each of the first strut, second strut, and third strut may be equally spaced about the center of rotation of the payload.

[0015] The first strut, the second strut, and the third strut may be connected to the base.

[0016] The base may be a single component.

[0017] The base may comprise more than one component.

[0018] The first actuator and the second actuator may be connected to the base.

[0019] At least the first connecting rod may be a single connecting rod having two prongs, each one of the prongs being connected to a payload.

[0020] The at least first connecting rod may be two separate connecting rods, each of the two separate connecting rods connected to both the first actuator and the payload.

[0021] Provided herein is a method of operation for pointing a payload with a two-axis pointing mechanism, the method comprising: actuating a first actuator, the first actuator connected to the payload by at least a first connecting rod and a bearing, the first actuator moving the first connecting rod to move the payload in a first direction; and actuating a second actuator, the second actuator connected to the payload by a second connecting rod and a bearing, the second actuator moving the second connecting rod to move the payload in a second direction, wherein the payload is movably connected to the first strut, the second strut, and a third strut by spherical bearings, the first strut, the second strut, and the third strut are movably connected to a base, and the first strut, the second strut, and the third strut constrain movement of the payload to rotation about a virtual pivot point.

[0022] Other aspects and features will become apparent to those skilled in the art upon review of the following description of several exemplary embodiments.

[0023] The figures included herewith are intended to illustrate various examples of the articles, methods, and apparatus of the present application. [Brief explanation of the drawings]

[0024] [Figure 1A] FIG. 1 is a schematic side perspective view of a two-axis payload orientation system, according to one embodiment. [Figure 1B] 1B is a different schematic side perspective view of the two-axis payload orientation system of FIG. 1A. [Figure 1C] 1B is a different side perspective view of the two-axis payload orientation system of FIG. 1A. FIG. [Figure 2] 1 is a flowchart of a method for operating a two-axis payload direction mechanism, according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Various devices or processes are described below to provide examples of each claimed embodiment. The embodiments described below do not limit the claimed embodiments, and the claimed embodiments may cover processes or devices different from those described below. The claimed embodiments are not limited to devices or processes having all of the features of any one device or process described below, or to features common to several or all of the devices described below.

[0026] The description of an embodiment having several components in communication with each other does not imply that all such components are required. On the contrary, various optional components are described to illustrate the wide variety of possible embodiments of the present invention.

[0027] Furthermore, although process steps, method steps, algorithms, etc. may be described (in this disclosure and / or claims) in a sequential order, such processes, methods, and algorithms may be configured to work in alternative orders. In other words, any sequence or order of steps that may be described does not necessarily indicate a requirement that the steps be performed in that order. Steps of processes described herein may be performed in any order that is practical. Additionally, some steps may be performed simultaneously.

[0028] Where a single device or article is described herein, it will be readily apparent that more than one device / article (whether they cooperate or not) can be used in place of the single device / article. Similarly, where more than one device or article (whether they cooperate or not) is described herein, it will be readily apparent that a single device / article can be used in place of the more than one device or article.

[0029] The following relates generally to payload pointing mechanisms, and more particularly to systems and methods for two-axis pointing of payloads, such as antenna reflectors. While antenna reflectors are discussed and shown herein, it will be understood that other payloads requiring pointing are contemplated by the present disclosure.

[0030] The disclosed two-axis pointing mechanism allows for the rotation of an antenna reflector around a virtual pivot point along two orthogonal axes. In a complete system, the pivot point for the antenna reflector's movement is at the radio frequency (RF) signal source / receiver, and the gimbaled payload becomes the parabolic reflector. In conventional systems, as the parabolic reflector rotates, its focal point moves away from the source, causing signal degradation.

[0031] Existing precision pointing mechanisms that operate in two axes, such as the system described in U.S. Pat. No. 9,172,154, result in a moving focal point because such systems are not designed to remain near a single source. These types of systems provide pointing accuracy but do not always maintain acceptable or desirable (i.e., excellent) RF signal performance.

[0032] The two-axis pointing mechanism of the present disclosure includes three struts movably connected to a payload. In one embodiment, the payload is an antenna. In one embodiment, the struts are connected to the payload by spherical bearings. In another embodiment, the struts may be movably connected to the payload by a movable connection other than a spherical bearing. The struts are movable by two fixed actuators. The struts and movable connections (e.g., spherical bearings) together enable movement of a reflector in two orthogonal axes, with each actuator driving movement in one of the axes. The focal point of the reflector is very close to a virtual pivot point of the reflector. Conventional pointing systems simply tilt the reflector. The system of the present disclosure rotates the reflector about the virtual pivot point.

[0033] The two-axis pointing mechanism allows for rotation of the reflector around a virtual pivot point, instead of simply tilting the reflector as is the case with conventional pointing mechanisms. This allows for minimal movement of the reflector focal point away from the source (or receiver). This is important because misalignment of even a few centimeters can degrade the RF signal.

[0034] A virtual pivot point is three-dimensional, allowing virtual pivoting in two orthogonal axes. The effect of a virtual pivot point in a pointing system is similar to rotating the entire antenna around its focal point.

[0035] The two-axis pointing mechanism of the present disclosure can provide various advantages such as reduced focus deviation, reduced pointing deviation, finer resolution, no moving harness, no moving RF components, etc. The two-axis pointing mechanism can eliminate the need for a retention and release mechanism for the reflector.

[0036] The dual-axis pointing mechanism can be used for Gregorian, Cassegrain, single-offset, center-fed, and Dragonian antennas. If the antenna has more than one focus or one or more subreflectors, such as in a dual-reflector antenna with an ellipsoidal or hyperbolic subreflector, the dual-axis pointing mechanism can be set in the configuration required to minimize signal degradation.

[0037] The two-axis pointing mechanism is particularly suited for space use cases, but is not limited to space applications.

[0038] 1A-1C, a two-axis pointing system 100 is shown, according to one embodiment.

[0039] 1B and 1C show the two-axis pointing system 100 of FIG. 1A from different perspectives.

[0040] The two-axis pointing system 100 includes an antenna reflector 102 mounted on a support structure 120, a first mast 110-1, a second mast 110-2, a third mast 110-3, a first rotary actuator 140, and a second rotary actuator 150. The three masts are collectively referred to herein as masts 110.

[0041] The antenna reflector 102 can be considered and referred to as a movable reflector. The antenna reflector 102 is configured to reflect RF signals to and from a fixed RF source / receiver, which can be a horn antenna.

[0042] The antenna reflector 102 is parabolic and has a focal point 104 near a virtual pivot point of the antenna reflector 102. The focal point 104 may be referred to as the reflector focal point.

[0043] In other embodiments, the two-axis pointing system may point at a payload other than the antenna reflector. In other embodiments, the payload may not have a focal point.

[0044] The support structure 120 is connected to the base 160 by the mast 110. In other embodiments, there may be no support structure for the antenna reflector 102 or for a non-antenna payload, and the mast may be connected directly to the antenna / payload.

[0045] In other embodiments, the base 160 to which the post 110 is connected may comprise more than one component.

[0046] The virtual pivot point 108 is the point around which the payload pivots. The virtual pivot point is near the focal point or pointing position of the payload. During payload pointing, the struts 110 constrain the payload's movement so that the payload rotates around the virtual pivot point. When the payload is in a central (or nominal) position, approximately halfway through the payload's pointing range, the intersection of the extrapolations of the first strut axis 112-1 along the length of the first strut 110-1, the second strut axis 112-2 along the length of the second strut 110-2, and the third strut axis 112-3 along the length of the third strut 110-3 (collectively the strut axes 112) is approximately the virtual pivot point. As the payload moves away from the middle of the pointing range, the intersection of the three strut axes 112 is no longer at the virtual pivot point.

[0047] Each of the struts 110 is coupled at a first end to the support structure 120 by a first spherical bearing. Each of the struts 110 is coupled to the base 160 by a second spherical bearing.

[0048] In other embodiments, movable connections other than spherical bearings can be used to connect the struts to the support and / or base.

[0049] 2A and 2B, the three support posts are equally spaced around the reflector 102. That is, adjacent support posts are disposed 120° apart around the reflector 102. However, in other embodiments, the support posts may be in any relative position that allows for the desired virtual pivot point, and therefore the desired movement, of the antenna reflector 102.

[0050] Similarly, the lengths of the three struts 110-1, 110-2, 110-3 relative to the size of the reflector 102 are important to create the desired virtual pivot point and movement of the antenna 102 (or other payload). In some embodiments, the length of each strut may be the same as the other struts, while in other embodiments, the lengths of the struts may be different.

[0051] 2A and 2B, the payload is an antenna reflector, and the virtual pivot point 108 is near the focal point 104 of the reflector, allowing movement of the antenna reflector while maintaining proximity to the focal point 104. In the embodiment of FIGS. 1A-1C, the first rotary actuator 140 and the second rotary actuator 150 are positioned approximately 90° apart relative to the center of the reflector 102. However, in other embodiments, the rotary actuators can be positioned closer or farther apart than 90° around the payload, as long as the desired range of movement is achieved.

[0052] The first and second rotary actuators 140, 150 are fixed actuators mounted on a base or support structure 160. In other embodiments, the column 110 and the actuators 140, 150 can be mounted on separate bases.

[0053] A first rotary actuator 140 is coupled to a crank 142 at a first end of the crank 142. The first crank 142 is connected to a first connecting rod 144 and a second connecting rod 145 at first ends of the rods 144, 145. The connecting rods 144, 145 are connected to the support structure 120 at second ends of the rods 144, 145. Movement of the first rotary actuator 140 moves the connecting rods 144, 145, which in turn moves the reflector 102.

[0054] 1A-1C, connecting rods 144 and 145 are disposed between first strut 110 and second strut 120. However, the configuration of the first actuator and connecting rods relative to the struts is not critical; that is, the configuration can be any configuration that allows for the desired movement.

[0055] In other embodiments, the first connecting rod 144 and the second connecting rod 145 may be a single Y-shaped connecting rod that connects to the reflector 102 in two locations. Connecting the first actuator 140 to the reflector 102 (or other payload) in two locations allows for control of the movement of the reflector 102 in two degrees of freedom.

[0056] To oversimplify the role of the first actuator, for example, if it is the only actuator present and is actuating the payload, the first actuator controls the movement of the reflector 102 along the X-axis 170, which causes rotation of the reflector 102 about the Y-axis 180. By connecting to the reflector 102 at at least one point, the reflector 102 is prevented from moving in the Z-axis. In the embodiment of Figure 1, there are two points of connection to the reflector 102.

[0057] A second rotary actuator 150 is coupled to a crank 152 at a first end thereof. A connecting rod 154 is coupled to a second end thereof. A spherical bearing 151 connects the crank 152 to the connecting rod 154. The spherical bearing connects the connecting rod 154 to the support structure 120 of the reflector 102. The connecting rod 154 controls one degree of freedom of the reflector 102. Movement of the second rotary actuator 150 moves the second connecting rod 154, which in turn moves the reflector 102.

[0058] Also, if we oversimplify the role of the second actuator, for example, if the second actuator is the only actuator present and is actuating the payload, the second actuator 150 controls the movement of the reflector 102 along the Y-axis 180, which in turn causes rotation of the reflector 102 about the X-axis 170.

[0059] While the movement of each individual actuator has been described above in simplified terms, the actual movement of the reflector is more complex. Together, the two rotary actuators rotate the reflector 102 about a virtual pivot point 108 (near the focal point 104) to steer the RF beam without affecting the signal, e.g., by losing focus. The movement of one actuator affects the movement of the other, and a transfer function exists that determines the actual movement of the reflector due to each actuator. While the first actuator may move the reflector primarily about the Y axis and the second actuator may move the reflector primarily about the X axis, both actuators may also move the reflector about other axes. That is, for example, the movement affected by the first actuator may be primarily about the Y axis, but based on the influence the second actuator has on the reflector's position and movement, the first actuator may also move the reflector to some extent about the X axis, and vice versa.

[0060] In some embodiments, the system 100 can use a linear actuator instead of a rotary actuator to actuate the reflector 102. As described above, when the actuator is a rotary actuator, a crank and connecting rod are used. When the actuator is a linear actuator, only a connecting rod is used.

[0061] Referring now to FIG. 2, a method 200 of operating a two-axis pointing system is shown, according to one embodiment.

[0062] The two-axis pointing system may be similar to system 100 of Figures 1A-1C.

[0063] The two-axis pointing system includes a base to which a first actuator and a second actuator are connected. The system further includes a first support, a second support, and a third support movably connected to the base. The base may be a single component or may comprise more than one component; that is, the actuator and the support may be connected to different base components.

[0064] Each of the first, second, and third struts is connected to the payload by a spherical bearing (or other bearing) on ​​the base side of the payload. For example, if the payload is a reflector, the strut is connected to the side of the reflector closest to the base, which is not used to reflect signals. In other embodiments, the strut can be indirectly connected to the payload through the payload's support structure.

[0065] In one embodiment, the three struts are spaced equally about 120° apart around the payload, the same distance from the center of the payload (e.g., reflector). In other embodiments, the struts may be any relative distance from the center of the payload and from each other.

[0066] The three struts support the payload and control its movement.

[0067] During payload pointing, the struts constrain the movement of the payload so that the payload rotates about a virtual pivot point. At the payload's center position when the payload is approximately in the middle of the payload's pointing range, the first strut axis, the second strut axis, and the third strut axis intersect at the payload's virtual pivot point. In embodiments where the payload has a focal point, such as an antenna reflector, the virtual pivot point is near the payload's focal point. In an antenna reflector, the focal point is as close as possible to either the source of the RF signal or the receiver of the RF signal.

[0068] In one embodiment, the first and second actuators are positioned approximately 90° apart relative to the payload's center of rotation, with each actuator representing one of two axes of a two-axis pointing mechanism. In other embodiments, the first and second actuators may be more or less than 90° apart.

[0069] In one embodiment, the first actuator is connected to the payload at two locations. The connections at the two locations can be achieved either by two separate connecting rods or by a single connecting element with two connecting rods, for example a Y or V. The two connecting rods are connected to the payload by spherical or rotary bearings.

[0070] By connecting to the payload in two places, the first actuator is able to control two degrees of freedom of movement of the payload.

[0071] In embodiments in which the first actuator is a rotary actuator, the first actuator includes a crank connected to a connecting rod by a spherical bearing.

[0072] In embodiments in which the first actuator is a linear actuator, the first actuator does not include a crank.

[0073] The second actuator is connected to the payload by a single connecting rod, which is connected to the payload by a spherical bearing.

[0074] In embodiments in which the second actuator is a rotary actuator, the second actuator includes a crank connected to a connecting rod by a spherical bearing.

[0075] In embodiments in which the second actuator is a linear actuator, the second actuator does not include a crank.

[0076] At 202, a first actuator (either a rotary actuator or a linear actuator) is actuated to move the payload in a first application direction, i.e., along a first actuator axis. The rotation of the payload is generally about an axis orthogonal to the first actuator axis. However, actuation of the strut, and therefore the payload, due to the first actuator depends on actuation of the second actuator, and vice versa. That is, for the first actuator to move the payload to the correct position, the position of the payload due to the second actuator must be considered, and therefore, the rotation of the payload due to the first actuator cannot occur only about an orthogonal axis.

[0077] Because the first actuator is connected to the payload in two places (two connecting rods or a single connecting rod in a Y-shape), rotation of the payload along the Z-axis is prevented when the first actuator is actuated (where the first actuator axis is the X-axis and the rotation axis is the Y-axis).

[0078] In other embodiments, the first actuator may be connected to the payload at one location.

[0079] At 208, a second actuator (either a rotary actuator or a linear actuator) is actuated to move the payload in a second application direction, i.e., along a second actuator axis. The rotation of the payload is generally about an axis orthogonal to the second actuator axis. However, as noted above, actuation of the second actuator depends on actuation of the first actuator, and vice versa. The first and second actuator axes are coplanar and may or may not be orthogonal.

[0080] Movement of the payload in the first and second directions together rotates and points the payload to a desired pointing position.

[0081] It should be understood that in some circumstances, the payload may be moved only by the first actuator or may be moved only by the second actuator to orient the payload in a desired direction.

[0082] While the above description provides examples of one or more devices, methods, or systems, it will be understood that other devices, methods, or systems may fall within the scope of the claims, as interpreted by one of ordinary skill in the art. [Explanation of symbols]

[0083] 100 2-axis pointing system 102 Antenna Reflector 104 Focus 108 Virtual pivot point 110 Post 110-1 First Pillar 110-2 Second Pillar 110-3 Third Pillar 112 Prop shaft 112-1 First support shaft 112-2 Second support shaft 112-3 Third support axis 120 Support structures 140 First rotary actuator 142 Crank 144 First connecting rod 145 Second connecting rod 150 Second rotary actuator 151 spherical bearing 152 Crank 154 connecting rod, second connecting rod 160 Base 170 X-axis 180 Y axis

Claims

1. 1. A two-axis pointing system for pointing a payload, comprising: A payload; a first actuator connected to the payload by at least a first connecting rod, the first actuator controlling movement of the payload along a first actuator axis by moving the first connecting rod; a second actuator connected to the payload by a second connecting rod, the second actuator moving the second connecting rod to control movement of the payload along a second actuator axis; a first strut, a second strut, and a third strut, each strut movably connected to the payload at a first end and movably connected to a base at a second end, the first strut, the second strut, and the third strut constraining movement of the payload caused by the first actuator and the second actuator to rotation about a virtual pivot point; A system comprising:

2. 2. The system of claim 1, wherein the first strut has a first strut axis along a length of the first strut, the second strut has a second strut axis along a length of the second strut, and the third strut has a third strut axis along a length of the third strut, and wherein an extrapolation of the first strut axis, the second strut axis, and the third strut axis intersect approximately at a virtual pivot point of the payload when the payload is centered midway through its pointing range.

3. The system of claim 1 , wherein the payload is an antenna reflector.

4. The system of claim 1 , wherein the payload has a focal point and the virtual pivot point is approximately at the focal point.

5. The system of claim 1 , wherein the first actuator axis and the second actuator axis are substantially orthogonal.

6. The system of claim 1 , wherein each of the first actuator and the second actuator is one of a rotary actuator and a linear actuator.

7. The system of claim 1 , wherein each of the first strut, the second strut, and the third strut is connected to the payload by a spherical bearing.

8. 10. The system of claim 1, wherein each of the first strut, the second strut, and the third strut is connected to the payload support structure by a spherical bearing.

9. The system of claim 1 , wherein each of the first strut, the second strut, and the third strut are approximately equally spaced about a center of rotation of the payload.

10. The system of claim 1 , wherein the first actuator and the second actuator are connected to the base.

11. 10. The system of claim 1, wherein the at least a first connecting rod is a single connecting rod having two prongs, each one of the prongs being connected to the payload.

12. The system of claim 1 , wherein at least one of the connecting rods is connected to the payload in a manner that allows relative movement along only one axis of rotation.

13. 2. The system of claim 1, wherein the at least a first connecting rod is two separate connecting rods, each of the two separate connecting rods connected to both the first actuator and the payload.

14. 10. The system of claim 1, wherein the payload is a dual-reflector antenna and the virtual pivot point is approximately at a second focus of an ellipsoidal or hyperbolic subreflector.

15. 1. A method of operation for pointing a payload with a two-axis pointing mechanism, comprising: activating a first actuator, the first actuator connected to a payload by at least a first connecting rod and a bearing, the first actuator moving the first connecting rod to move the payload in a first direction; activating a second actuator, the second actuator connected to the payload by a second connecting rod and a bearing, the second actuator moving the second connecting rod to move the payload in a second direction; Including, The method of claim 1, wherein the payload is movably connected to a first support column, a second support column, and a third support column by spherical bearings, the first support column, the second support column, and the third support column are movably connected to a base, and the first support column, the second support column, and the third support column restrict movement of the payload to rotation about a virtual pivot point.

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