BACKGROUND

[0001] Mechanical assemblies may include multiple subassemblies that support various techniques for assembly, disassembly, and reassembly. In some examples, an implementation of an assembly may benefit from a relatively precise positioning between subassemblies. For example, in an antenna system implementation, a first subassembly may be associated with a mounting pedestal and a second subassembly may be associated with an antenna assembly. An alignment of the antenna system, such as an antenna boresight alignment or an antenna positioning alignment (e.g., between the antenna assembly and the mounting pedestal), may be relatively more-precise when one or more fastening systems between the first subassembly and the second subassembly provide a relatively precise positioning between the first subassembly and the second subassembly, including such alignment as provided during an assembly operation or a reassembly operation.

SUMMARY

[0002] Methods and systems are described for positioning precision between subassemblies. In some assemblies, implementing a fastening system that supports relatively precise positioning or repositioning between subassemblies may be associated with an overconstrained condition or an interference between components, which may impede or prevent assembly, disassembly, or reassembly operations. For example, an alignment tolerance between a precision-formed hole of a first subassembly and a precision-formed hole of a second subassembly may not support a precision-formed pin being freely inserted through or removed from the precision-formed holes (e.g., due to such precision-formed holes being non-concentric, misaligned, or otherwise blocking or binding during an assembly or disassembly operation). Accordingly, in some examples, precision-formed pins and precision-formed holes may be unsuitable for supporting some assembly, disassembly, or reassembly operations or techniques.

[0003] In accordance with examples as disclosed herein, a fastening system may be configured with various interfaces (e.g., physical interfaces, mating interfaces, surfaces) that support movement (e.g., one or more degrees of freedom) between subassemblies during assembly or disassembly operations, and support one or more constraints between subassemblies in an assembled condition. For example, a first subassembly may be associated with a set of one or more first coupling locations and a second subassembly may be associated with a set of one or more second coupling locations. In an assembled condition, each first coupling location of the first subassembly may be coupled with (e.g., connected with, fastened with, fixed relative to) a respective second coupling location of the second subassembly (e.g., at a coupling location of the assembly that is associated with a respective first coupling location and a respective second coupling location) using a respective fastening system in accordance with examples as disclosed herein. The fastening system may support one or more degrees of freedom associated with the coupling locations during an assembly operation or a disassembly operation to facilitate component assembly or disassembly (e.g., a radial degree of freedom to facilitate an insertion or a removal of a fastener through holes associated with the coupling locations) and, in an assembled condition, the one or more degrees of freedom may instead be associated with (e.g., replaced with, modified to) one or more constraints (e.g., a radial constraint between the fastener and each subassembly, where a radial constraint may refer to a translational constraint along directions radial to an associated axis) that supports a relatively precise alignment or realignment between the first subassembly and the second subassembly. In some examples, the fastening system may include a fastener configured for a radial constraint (e.g., a precision fit, a slip fit) with one or more bushings. The bushings may be configured for a radial degree of freedom with the subassemblies during an assembly operation or a disassembly operation (e.g., when not preloaded into a mating interface by the fastener), and for a radial constraint with the subassemblies in an assembled condition (e.g., when preloaded into a mating interface by the fastener). By supporting one or more degrees of freedom during assembly or disassembly operations and one or more constraints in an assembled condition, fastening systems in accordance with examples as disclosed herein may support improved assembly or disassembly operations while also supporting relatively precise positioning between subassemblies.

[0004] Further scope of the applicability of the described methods and systems will become apparent from the following detailed description, claims, and drawings. The detailed description and specific examples are given by way of illustration only, since various changes and modifications within the scope of the description will become apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 illustrates an example of an assembly that supports techniques for positioning precision between subassemblies in accordance with examples as disclosed herein.

[0006] FIGs. 2 and 3 illustrate an example of a fastening system that supports techniques for positioning precision between subassemblies in accordance with examples as disclosed herein.

[0007] FIG. 4 illustrates an example of an assembly that supports techniques for positioning precision between subassemblies in accordance with examples as disclosed herein.

[0008] FIG. 5 shows a flowchart illustrating methods that support techniques for positioning precision between subassemblies in accordance with examples as disclosed herein.

DETAILED DESCRIPTION

[0009] Methods and systems for positioning precision between subassemblies are described. In some assemblies, implementing a fastening system that supports relatively precise positioning or repositioning between subassemblies may be associated with an overconstrained condition or an interference between components, which may impede or prevent assembly, disassembly, or reassembly operations. For example, an alignment tolerance between a precision-formed hole of a first subassembly and a precision-formed hole of a second subassembly may not support a precision-formed pin being freely inserted through or removed from the precision-formed holes (e.g., due to such precision-formed holes being non-concentric, misaligned, or otherwise blocking or binding during an assembly or disassembly operation). Accordingly, in some examples, precision-formed pins and precision-formed holes may be unsuitable for supporting some assembly, disassembly, or reassembly operations or techniques.

[0010] In accordance with examples as disclosed herein, a fastening system may be configured with various interfaces (e.g., physical interfaces, mating interfaces, surfaces) that support movement (e.g., one or more degrees of freedom) between subassemblies during assembly or disassembly operations, and support one or more constraints between subassemblies in an assembled condition. For example, a first subassembly may be associated with a set of one or more first coupling locations and a second subassembly may be associated with a set of one or more second coupling locations. In an assembled condition, each first coupling location of the first subassembly may be coupled with (e.g., connected with, fastened with, fixed relative to) a respective second coupling location of the second subassembly (e.g., at a coupling location of the assembly that is associated with a respective first coupling location and a respective second coupling location) using a respective fastening system in accordance with examples as disclosed herein. The fastening system may support one or more degrees of freedom associated with the coupling locations during an assembly operation or a disassembly operation to facilitate component assembly or disassembly (e.g., a radial degree of freedom to facilitate an insertion or a removal of a fastener through holes associated with the coupling locations) and, in an assembled condition, the one or more degrees of freedom may instead be associated with (e.g., replaced with, modified to) one or more constraints (e.g., a radial constraint between the fastener and each subassembly, where a radial constraint may refer to a translational constraint along directions radial to an associated axis) that supports a relatively precise alignment or realignment between the first subassembly and the second subassembly. In some examples, the fastening system may include a fastener configured for a radial constraint (e.g., a precision fit, a slip fit) with one or more bushings, and the bushings may be configured for a radial degree of freedom with the subassemblies during an assembly or disassembly operation (e.g., when not preloaded into a mating interface by the fastener) and a radial constraint with the subassemblies in an assembled condition (e.g., when preloaded into a mating interface by the fastener). By supporting one or more degrees of freedom during assembly or disassembly operations and one or more constraints in an assembled condition, fastening systems in accordance with examples as disclosed herein may support improved assembly or disassembly operations while also supporting relatively precise positioning between subassemblies.

[0011] FIG. 1 illustrates an example of an assembly 100 that supports techniques for positioning precision between subassemblies in accordance with examples as disclosed herein. The assembly 100 includes a subassembly 105 and a subassembly 110, which may be coupled with one another at coupling locations 120 (e.g., a coupling location 120-a, a coupling location 120-b, and a coupling location 120-c). Although the assembly 100 illustrates an example of coupling subassemblies 105 and 110 at three coupling locations 120, the described techniques for positioning precision between subassemblies 105 and 110 may be implemented with any quantity of one or more coupling locations 120. Aspects of the assembly 100 may be described with reference to an x-direction, a y-direction, and a z- direction in accordance with the illustrated coordinate system.

[0012] In some examples, the assembly 100 may illustrate aspects of an antenna system. For example, the subassembly 105 may be an example of or otherwise include a mounting pedestal, which may be associated with mounting the antenna system to a fixed location (e.g., at a grounded location, to a foundation, to a building) or a mobile location (e.g., to a vehicle). In some examples, the subassembly 110 may be an example of or otherwise include an antenna assembly, such as a direct radiating antenna assembly, a reflector antenna assembly, or a phased array antenna assembly, among other examples. For example, the subassembly 110 may include or be coupled with a fixed antenna assembly (e.g., an antenna assembly with a fixed alignment relative to the subassembly 110), or may include or be coupled with an antenna positioning system configured for aligning a direction of signaling of an antenna assembly (e.g., for aligning a boresight of an antenna) relative to the subassembly 110.

[0013] In the example of assembly 100, each coupling location 120 may be associated with respective coupling locations of the subassembly 105 and the subassembly 110 that form a joint (e.g., a double shear joint, a knuckle joint) between the subassembly 105 and the subassembly 110. For example, the coupling location 120-a may be associated with a portion (e.g., a single eye portion) of a first joint that includes a projection 125-a of the subassembly 105, and the coupling location 120-a may be associated with a portion (e.g., a double eye portion) of the first joint that includes projections 130-a-l and 130-a-2 of the subassembly 110. The coupling location 120-b may be associated with a portion of a second joint that includes a projection 125-b of the subassembly 105, and the coupling location 120-b may be associated with a portion of the second joint that includes projections 130-b-l and 130-b-2 of the subassembly 110. The coupling location 120-c may be associated with a portion of a third joint that includes a projection 125-c of the subassembly 105, and the coupling location 120-c may be associated with a portion of the third joint that includes projections 130-c-l and 130-C-2 of the subassembly 110. As used herein, a projection may refer to a portion of a subassembly that supports a coupling of the subassembly with another subassembly, and so forth, (e.g., at a joint) via a fastening system 150. The projection may include an extension from a structural component of the subassembly (e.g., as illustrated with respect to the projections 125 and 130) or may include another feature of a subassembly such as a hole through a body portion of the subassembly, which may support a coupling in accordance with a double shear joint or a single shear joint, among other configurations. [0014] Some joints that may be implemented at coupling locations 120 include precision holes formed in (e.g., drilled through, reamed through) projections 125 and projections 130, through which a precision- formed pin (e.g., a machined pin, a ground pin, a dowel pin, a shoulder bolt) may be inserted. Such techniques may be associated with at least a radial constraint between projections 125 and projections 130 (e.g., a translational constraint along radial directions relative to axes associated with such holes and pins). In some examples, such a radial constraint may be supported in accordance with a class of fit between such holes and pins (e.g., a slip fit, an interference fit), which may be associated with various mechanical tolerancing techniques. However, when implementing such joints at multiple coupling locations 120 between the subassembly 105 and the subassembly 110, an alignment tolerance between holes through projections 125 and holes through projections 130 may not support a precision-formed pin being freely inserted through or removed from the holes (e.g., due to a hole through a projection 125 being non-concentric, misaligned, or otherwise blocking or binding relative to one or more holes through projections 130 during an assembly operation). Accordingly, in some examples, implementing precision- formed pins with precision- formed holes through projections 125 and projections 130 may be unsuitable for supporting some assembly, disassembly or reassembly operations or techniques for the assembly 100.

[0015] In accordance with examples as disclosed herein, the assembly 100 may implement a respective fastening system 150 at each of the coupling locations 120 (e.g., a fastening system 150-a at the coupling location 120-a, a fastening system 150-b at the coupling location 120-b, a fastening system 150-c at the coupling location 120-c) for coupling the subassembly 105 with the subassembly 110. Each fastening system 150 may be configured with various interfaces (e.g., physical interfaces, mating interfaces, surfaces) that support one or more degrees of freedom between the subassembly 105 and the subassembly 110 during assembly or disassembly operations, and support one or more constraints between the subassembly 105 and the subassembly 110 in an assembled condition.

[0016] In some examples, each fastening system 150 may include a fastener, such as a shoulder bolt, configured for a radial constraint (e.g., a precision fit, a slip fit) with one or more bushings of the fastening system 150. The bushings may be configured to support radial movement (e.g., a radial degree of freedom) with one or both of the subassembly 105 or the subassembly 110 during an assembly or disassembly operation (e.g., when the bushings are not preloaded into a mating interface, such as a mating surface associated with the subassembly 105 or the subassembly 110 that is configured to constrain the bushings along radial directions, by the fastener). The bushings also may be configured for a radial constraint with one or both of the subassembly 105 or the subassembly 110 in an assembled condition, for example, when the bushings are preloaded into a mating interface (e.g., a mating surface) associated with the subassembly 105 or the subassembly 110 by the fastener (e.g., a load imparted by the fastener when the fastener is tightened and is thereby configured clamp mating components together). As referred to herein, components or interfaces configured for a radial constraint may be configured in a condition associated with a translational constraint (e.g., an immobility, a restriction of movement, a prevention of movement) along directions radial to one or more axes corresponding to an associated component or interface. By supporting relative movement (e.g., one or more degrees of freedom) during assembly or disassembly operations and relative immobility (e.g., one or more constraints) in an assembled condition, the fastening system 150 may support improved operations for assembling or disassembling the assembly 100 (e.g., for coupling the subassembly 105 with the subassembly 110) while also supporting relatively precise positioning between the subassembly 105 and the subassembly 110.

[0017] FIGs. 2 and 3 illustrate an example of a fastening system 150-d that supports techniques for positioning precision between subassemblies in accordance with examples as disclosed herein. The fastening system 150-d may be an example for implementing one or more of the fastening systems 150 of the assembly 100, among other examples for coupling subassemblies 105 and 110 at a coupling location 120 (e.g., for coupling at a double shear joint between subassemblies).

[0018] FIG. 2 illustrates an exploded view of an example of components that may be included in the fastening system 150-d (e.g., in an unassembled condition, as an example of a kit of parts). The fastening system 150-d may be configured for coupling a first subassembly (e.g., a subassembly 105) with a second subassembly (e.g., a subassembly 110), and may include at least a fastener 210, a bushing 220, and a bushing 260. In an assembled condition of the first subassembly and the second subassembly, the fastener 210 may be configured to provide a clamping load that pulls the bushing 220 and the bushing 260 toward one another (e.g., when the fastener 210 is tightened), which may be associated with maintaining a preload between the bushing 220 and the bushing 260 (e.g., along an axis 211, associated with a tensile load of the fastener 210 that is reacted via at least a compressive load of the bushing 220, such as into a bushing 230 or other component, and a compressive load of the bushing 260, such as into a bushing 250 or other component). In some examples, such a preload may support the fastening system 150-d establishing one or more constraints (e.g., radial constraints) between the first subassembly and the second subassembly (e.g., in an assembled condition).

[0019] The fastener 210 may be associated with an axis 211, and may include an interface 212, an interface 213, and an interface 214, each of which may be concentric with the axis 211. For example, the fastener 210 may be a shoulder bolt, such that the interface 212, the interface 213, and the interface 214 may each correspond to a respective portion of a common cylindrical surface of the fastener 210. The common cylindrical surface of the fastener 210 may be a non- threaded portion (e.g., a shoulder, a shank) of the fastener 210. In some examples, the interface 213 may be configured to support at least a radial constraint between the fastener 210 and the first subassembly (e.g., a precision cylindrical bore or slot, of or otherwise associated with the first subassembly, mating surfaces that suppress movement in radial directions) relative to the axis 211. In some examples, the fastener 210 may include a threaded portion 215 (e.g., an external threaded portion), and a preload supported by the fastener 210 may be based at least in part on mating the threaded portion 215 with a threaded portion 265 (e.g., an internal threaded portion) of the bushing 260. An outer diameter of the threaded portion 215 may be equal to or less than a diameter of the fastener at the interfaces 212, 213, and 214. The fastener 210 also may include a head portion 216, which may react a generated tensile preload of the fastener 210 against the bushing 220 (e.g., via a physical contact or compressive load between the head portion 216 and the bushing 220 that opposes the tensile preload of the fastener 210). In various examples, the head portion 216 may include an internal polygonal portion (e.g., an Allen socket), an external polygonal portion (e.g., a hexagonal head), a screw head, or some other feature that supports rotating the fastener 210 (e.g., about the axis 211) to engage the threaded portion 215 with the threaded portion 265.

[0020] The bushing 220 may be associated with an axis 221 and may include various interfaces that support the described techniques for precision positioning between the first subassembly and the second subassembly. For example, the bushing 220 may include an interface 222 (e.g., an internal surface of the bushing 220 that is concentric with the axis 221) that is configured to couple with the interface 212 in accordance with, and therefore limited by, at least a radial constraint (e.g., relative to the axis 211, between the axis 221 and the axis 211). In some examples, the interface 222 may be associated with a cylindrical bore that is configured for a precision fit (e.g., a slip fit, a fit within a threshold tolerance) with the interface 212. The fit between the interface 212 and the interface 222 may support a rotational degree of freedom (e.g., a rotational degree of freedom about or between the axis 211 and the axis 221, a twisting degree of freedom). The bushing 220 also may include an interface 223 (e.g., concentric with the axis 221) that is configured to support a degree of freedom during an assembly or disassembly operation and support a constraint between the first subassembly and the second subassembly in an assembled condition. For example, the interface 223 may be configured for coupling the bushing 220 with the second subassembly in accordance with at least a radial constraint (e.g., relative to the axis 221, between the axis 221 and an axis associated with or otherwise fixed relative to the second subassembly) while a preload is maintained by the fastener 210 (e.g., when the interface 223 is loaded in contact with a bushing 230 or other component, such as by a tensile load of the fastener 210). The interface 223 also may support at least a radial degree of freedom between the bushing 220 and the second subassembly (e.g., relative to the axis 221, between the axis 221 and an axis associated with or otherwise fixed relative to the second subassembly) while the preload is removed or otherwise not maintained by the fastener 210 (e.g., when the interface 223 is not in contact with a bushing 230 or another component).

[0021] To support a radial constraint, the interface 223 may include various types of surfaces, including one or more surfaces that are non-perpendicular with the axis 221 or the axis 211, among other axes. In some examples, the interface 223 may include a revolute surface (e.g., about the axis 221), which may support a rotational degree of freedom (e.g., about the axis 221) between the bushing 220 and the second subassembly. In some examples, the interface 223 may include a convex spherical surface of the bushing 220. The interface 223 may allow an angular misalignment between the bushing 220 and the second subassembly, such as an angular rotation about one or more axes perpendicular to the axis 221 or an axis associated with a hole through the second subassembly. For example, the convex spherical surface of the interface 223 of the bushing 220 may remain in contact with a mating concave spherical surface associated with the second subassembly while maintaining an associated radial constraint under preload. In various examples, such mating spherical surfaces may be associated with solid angles that are different than one another, which may be provided to support such angular misalignment. Supporting such an angular misalignment at or between subassemblies may reduce or eliminate a bending loading of the fastener 210. In some other examples, the interface 223 may not include a revolute surface, in which case the interface 223 may not support a rotational degree of freedom (e.g., about the axis 221 or axes perpendicular to the axis 221) between the bushing 220 and the second subassembly.

[0022] The bushing 260 may be associated with an axis 261, and also may include various interfaces that support the described techniques for precision positioning between the first subassembly and the second subassembly. For example, the bushing 260 may include an interface 262 (e.g., concentric with the axis 261 and being an interior surface of the bushing

260 with respect to the fastener 210) that is configured to couple with the interface 214 in accordance with at least a radial constraint (e.g., relative to the axis 211, between the axis 261 and the axis 211). In some examples, the interface 262 may be associated with a cylindrical bore that is configured for a precision fit (e.g., a slip fit, a fit within a threshold tolerance) with the interface 214, which may support a rotational degree of freedom (e.g., a rotational degree of freedom about or between the axis 211 and the axis 261, a twisting degree of freedom). The bushing 260 also may include an interface 263 (e.g., concentric with the axis 261) that is configured to support a degree of freedom during an assembly or disassembly operation and support a constraint between the first subassembly and the second subassembly in an assembled condition. For example, the interface 263 may be configured for coupling the bushing 260 with the second subassembly in accordance with at least a radial constraint (e.g., relative to the axis 261, between the axis 261 and an axis associated with or otherwise fixed relative to the second subassembly) while a preload is maintained by the fastener 210, and may support at least a radial degree of freedom between the bushing 260 and the second subassembly (e.g., relative to the axis 261, between the axis 261 and an axis associated with or otherwise fixed relative to the second subassembly) while the preload is removed or otherwise not maintained by the fastener 210.

[0023] To support a radial constraint, the interface 263 also may include various types of surfaces, including one or more surfaces that are non-perpendicular with the axis 261 or the axis 211, among other axes. In some examples, the interface 263 may include a revolute surface (e.g., about the axis 261), which may support a rotational degree of freedom (e.g., about the axis 261) between the bushing 260 and the second subassembly. In some examples, the interface 263 may include a convex spherical surface of the bushing 260. The interface 263 may allow an angular misalignment between the bushing 260 and the second subassembly, such as an angular rotation about one or more axes perpendicular to the axis

261 or an axis associated with a hole through the second subassembly. For example, the convex spherical surface of the interface 263 of the bushing 260 may remain in contact with a mating concave spherical surface associated with the second subassembly while maintaining an associated radial constraint under preload. In various examples, such mating spherical surfaces may be associated with solid angles that are different than one another, which may be provided to support such angular misalignment. Supporting such an angular misalignment at or between subassemblies may reduce or eliminate a bending loading of the fastener 210. In some other examples, the interface 263 may not include a revolute surface, in which case the interface 263 may not support a rotational degree of freedom (e.g., about the axis 261 or axes perpendicular to the axis 261) between the bushing 260 and the second subassembly.

[0024] In some examples, the fastening system 150-d may include a bearing 240, which may be associated with an axis 241. The bearing 240 may include an interface 242 (e.g., concentric with the axis 241) that is configured to couple with the interface 213 in accordance with at least a radial constraint (e.g., relative to the axis 211, between the axis 211 and the axis 241). In some examples, the interface 242 may be associated with a cylindrical bore that is configured for a precision fit (e.g., a slip fit, a fit within a threshold tolerance) with the interface 213, which may support a rotational degree of freedom between the bearing 240 and the fastener 210 (e.g., a rotational degree of freedom about or between the axis 211 and the axis 241, a rotational degree of freedom between the interface 242 and the interface 213, a twisting degree of freedom). The bearing 240 also may include an interface 243 that is configured to couple the bearing 240 with the first subassembly in accordance with at least a radial constraint (e.g., relative to the axis 241 or axis of the interface 243, between the axis 241 or axis of the interface 243 and an axis associated with a mounting hole in the first subassembly). In some examples, a bearing 240 may be a spherical, or similar bearing configured to provide a spherical degree of freedom between a first portion of the spherical bearing (e.g., including the interface 242) and a second portion of the spherical bearing (e.g., including the interface 243), which may support a degree of misalignment between holes, surfaces, or other features of the first subassembly and the second subassembly. In examples of the fastening system 150-d that do not include a bearing 240, a first subassembly (e.g., a projection 125) may include an interface (e.g., a cylindrical bore) that is configured to couple with the interface 213 in accordance with at least a radial constraint (e.g., in accordance with a precision fit, in accordance with a slip fit), which may otherwise support a rotational degree of freedom (e.g., a rotational degree of freedom about or between the axis 211 and the axis 241). [0025] In some examples, the fastening system 150-d may include a bushing 230, which may be associated with an axis 231. The bushing 230 may include an interface 232 which may be configured to couple with (e.g., to be in contact with, to mate with) the interface 223 of the bushing 220. In some examples, the interface 232 may include one or more surfaces that are non-perpendicular with the axis 211 or the axis 231, among other axes. In some examples, the interface 232 may include a concave spherical surface of the bushing 230, which may be associated with a solid angle that is different than a solid angle associated with a convex spherical surface associated with the interface 223 (e.g., to support an angular misalignment between the axis 231 and the axis 221). The bushing 230 also may include an interface 233 that is configured to couple with the second subassembly (e.g., with a first projection 130) in accordance with at least a radial constraint (e.g., relative to the axis 231). In some examples, the interface 233 may be configured for a precision fit, a slip fit, or a press fit with a mating hole of the second subassembly. In some other examples, the interface 233 may be configured for a threaded connection with the second subassembly. The bushing 230 also may include an interface 234 (e.g., a flange interface), which may support the bushing 230 reacting a preload of the fastener 210 (e.g., via the bushing 220) into the second subassembly.

[0026] In some examples, the bushing 230 may include an opening 235 to receive the bushing 220. A diameter or cross-sectional area of the opening 235 may be larger than a corresponding diameter or cross-sectional area of the bushing 220 (e.g., of a portion 224 of the bushing 220), which may support a radial degree of freedom between the bushing 220 and the bushing 230 (e.g., between the axis 221 and the axis 231, when the fastener 210 is not maintaining a preload, when the interface 223 is not in contact with the interface 232). Further, the bushing 230 may include an opening 236 through which the fastener 210 may be inserted. A diameter or cross-sectional area of the opening 236 may be larger than a corresponding diameter or cross-sectional area of the fastener 210, which may support a radial degree of freedom between the fastener 210 and the bushing 230 (e.g., between the axis 211 and the axis 231). In examples of the fastening system 150-d that do not include the bushing 230, an interface 232 may be replaced by a corresponding interface of the second subassembly, such as a precision-formed surface (e.g., a surface of a first projection 130), a concave spherical surface) of the second subassembly with which the interface 223 of the bushing 220 may couple (e.g., contact, mate) to provide a radial constraint between the bushing 220 and the second subassembly (e.g., when preloaded by the fastener 210). [0027] Additionally, or alternatively, in some examples, the fastening system 150-d may include a bushing 250, which may be associated with an axis 251. The bushing 250 may include an interface 252 which may be configured to couple with the interface 263 of the bushing 260. In some examples, the interface 252 may include one or more surfaces that are non-perpendicular with the axis 211 or the axis 251, among other axes. In some examples, the interface 252 may include a concave spherical surface of the bushing 250, which may be associated with a solid angle that is different than a solid angle associated with a convex spherical surface associated with the interface 263 (e.g., to support an angular misalignment between the axis 251 and the axis 261). The bushing 250 also may include an interface 253 that is configured to couple with the second subassembly (e.g., with a second projection 130) in accordance with at least a radial constraint (e.g., relative to the axis 251). In some examples, the interface 253 may be configured for a precision fit, a slip fit, or a press fit with a mating hole of the second subassembly. In some other examples, the interface 253 may be configured for a threaded connection with the second subassembly. The bushing 250 also may include an interface 254 (e.g., a flange interface), which may support the bushing 250 reacting a preload of the fastener 210 (e.g., via the bushing 260) into the second subassembly.

[0028] In some examples, the bushing 250 may include an opening 255 to receive the bushing 260. A diameter or cross-sectional area of the opening 255 may be larger than a corresponding diameter or cross-sectional area of the bushing 260 (e.g., of a portion 264 of the bushing 260), which may support a radial degree of freedom between the bushing 260 and the bushing 250 (e.g., between the axis 261 and the axis 251, when the fastener 210 is not maintaining a preload, when the interface 263 is not in contact with the interface 252). Further, the bushing 250 may include an opening 255 through which the fastener 210 may be inserted. A diameter or cross-sectional area of the opening 255 may be larger than a corresponding diameter or cross-sectional area of the fastener 210, which may support a radial degree of freedom between the fastener 210 and the bushing 250 (e.g., between the axis 211 and the axis 251). In examples of the fastening system 150-d that do not include a bushing 250, an interface 252 may be replaced by a corresponding interface of the second subassembly, such as a precision-formed surface (e.g., a surface of a second projection 130, a concave spherical surface) of the second subassembly with which the interface 263 of the bushing 260 may couple (e.g., contact, mate) to provide a radial constraint between the bushing 260 and the second subassembly (e.g., when preloaded by the fastener 210). [0029] In some examples of the fastening system 150-d that include the bushing 250, the bushing 260 may include an interface 266 and the bushing 250 may include an interface 257, which may (e.g., in combination) be configured to limit rotation of the bushing 260 (e.g., about the axis 261, based at least in part on physical contact between the interface 256 and the interface 266). For example, an interface 266 may be associated with a hexagonal or other polygonal perimeter or cross-section, and the interface 257 may be associated with a lobed or otherwise corresponding opening configured to receive or otherwise couple with the interface 266 (e.g., in accordance with a loose or imprecise fit). Such contacting interfaces may suppress rotation of the bushing 260 within the bushing 250 as a result of, for example, rotating (e.g., tightening, loosening) the fastener 210.

[0030] Additionally, or alternatively, some examples of the fastening system 150-d that include a bushing 250 also may include a retainer 270 (e.g., a retaining clip, a snap ring), which may be configured to couple with the bushing 250 (e.g., in a slot or groove in or along the opening 255). A retainer 270 may be configured to limit a displacement of the bushing 260, relative to the bushing 250, along the axis 261 (e.g., in a direction opposite the interface 263, to capture the bushing 260 in the bushing 250).

[0031] The fastening system 150-d illustrates an example of components that are configured to support a degree of freedom (e.g., a radial degree of freedom) between components to facilitate assembly operations or disassembly operations (e.g., of a subassembly 105 and a subassembly 110). For example, for cases in which a bearing 240 is included, the bearing 240 may be coupled with a first subassembly, which may involve slipping, pressing, threading, or otherwise mating the bearing 240 with a hole or other feature of the first subassembly (e.g., a hole or other feature of a projection 125), which may establish a radial constraint between the first subassembly and the interface 243. In some cases, the interface 243 may establish a fixed relationship between the bearing 240 and the first subassembly. The bearing 240 may support one or more rotational degrees of freedom between the interface 243 and the interface 242, which may support various misalignments between the first subassembly and the second subassembly, but the interface 242 may be radially constrained relative to the interface 243. For example, the axis 241 may be skewed or twisted relative to an axis associated with the interface 243, but the axis 241 may be coincident with such an axis at a point (e.g., as a point constraint, supporting at least a radial constraint between the axis 241 and the first subassembly, a coupling relationship between the interface 242 and the interface 243 that permits relative rotations and suppresses relative translations). In some examples, a rotational degree of freedom provided by a bearing 240 may facilitate an insertion of the fastener 210 through various components of the fastening system 150-d or may reduce a loading of the fastening system 150-d (e.g., a bending loading of the fastener 210) in an assembled condition, among other benefits. In some other examples, installing a bearing 240 with the first subassembly may be omitted, such as for examples in which an interface corresponding to the interface 242 (e.g., a cylindrical bore, a precision bore, a precision slot) is formed as part of the first subassembly.

[0032] For cases in which a bushing 230 is included, the bushing 230 may be coupled with a second subassembly, which may involve slipping, pressing, threading, or otherwise mating the bushing 230 with a hole or other feature of the second subassembly (e.g., a hole or other feature of a first projection 130), which may establish at least a radial constraint, if not a fixed relationship, between the second subassembly and the interface 232. In some other examples, installing a bushing 230 with the second subassembly may be omitted, such as for examples in which an interface corresponding to the interface 232 (e.g., a concave spherical surface) is formed as part of the second subassembly (e.g., as a formed surface of the first projection 130). Further, for cases in which a bushing 250 is included, the bushing 250 may be coupled with the second subassembly, which may involve slipping, pressing, threading, or otherwise mating the bushing 250 with a hole or other feature of the second subassembly (e.g., a hole or other feature of a second projection 130), which may establish at least a radial constraint, if not a fixed relationship between the second subassembly and the interface 252. In some other examples, installing a bushing 250 with the second subassembly may be omitted, such as for examples in which an interface corresponding to the interface 252 (e.g., a concave spherical surface) is formed as part of the second subassembly (e.g., as a surface of the second projection 130).

[0033] To assemble the fastening system 150-d at a joint between the first subassembly (e.g., at a coupling location of the first subassembly associated with a projection 125) and the second subassembly (e.g., at a coupling location of the second subassembly associated with two projections 130), a bushing 260 may be inserted into a bushing 250 (e.g., where applicable), which may include inserting the bushing 260 into an opening 255 of the bushing 250. With the opening 255 having a greater diameter or cross-section than the bushing 260 (e.g., when the interface 263 is not preloaded or otherwise in contact with the interface 252), the bushing 260 may have a radial degree of freedom relative to the bushing 250 (e.g., at least a radial degree of freedom between the axis 261 and the axis 251). In some examples, such a radial degree of freedom may be supported in the absence of a bushing 260, such as when a surface of the second subassembly includes an interface to mate with the interface 263 (e.g., with or without an opening or other portion corresponding to the opening 255). After insertion of the bushing 260 in the bushing 250, a retainer 270 may be installed in a groove of the bushing 250, which may retain the bushing 260 in the bushing 250 (e.g., along the axis 251 or along the axis 261). In some examples, a bushing 260 and a retainer 270 may be assembled with a bushing 250 before coupling the bushing 250 with a second subassembly. Similarly, a bushing 220 may be inserted into a bushing 230 (e.g., where applicable), which may include inserting the bushing 220 into an opening 235 of the bushing 230. With the opening 235 having a greater diameter or cross-section than the bushing 220 (e.g., when the interface 223 is not preloaded or otherwise in contact with the interface 232), the bushing 220 may have a radial degree of freedom relative to the bushing 230 (e.g., at least a radial degree of freedom between the axis 221 and the axis 231). In some examples, such a radial degree of freedom may be supported in the absence of a bushing 230, such as when a surface of the second subassembly includes an interface to mate with the interface 223 (e.g., with or without an opening or other portion corresponding to the opening 235).

[0034] The fastener 210 may be inserted through the bushing 220 (e.g., after or before inserting the bushing 220 in a bushing 230), through the bushing 230 (e.g., where applicable), through the bearing 240 (e.g., where applicable), through the bushing 250 (e.g., where applicable), and through the bushing 260. In some examples, the fastener 210 may be radially constrained relative to the bushing 220 (e.g., due to a radial constraint associated with the interface 212 and the interface 222, such as a slip fit or other precision fit), radially constrained relative to the first subassembly (e.g., radially constrained relative to the bearing 240, where applicable, due to a radial constraint associated with the interface 213 and the interface 242, such as a slip fit or other precision fit), and radially constrained relative to the bushing 260 (e.g., due to a radial constraint associated with the interface 214 and the interface 262, such as a slip fit or other precision fit). However, the fastener 210, the bushing 220, and the bushing 260 may not yet be constrained (e.g., radially constrained) relative to the second subassembly. For example, the radially-constrained combination of the fastener 210, the bushing 220, the first subassembly (e.g., the bearing 240), and the bushing 260 may have a degree of freedom (e.g., a radial degree of freedom, relative to the second subassembly) supported by a combination of the opening 235 (e.g., where applicable) being larger than the bushing 220 (e.g., larger than the portion 224), by the opening 236 (e.g., where applicable) being larger than the fastener 210 (e.g., larger than the interface 212 or other diameter or dimension of the fastener 210), by the opening 255 (e.g., where applicable) being larger than the fastener 210 (e.g., larger than the interface 214 or other diameter or dimension of the fastener 210), and by the opening 255 (e.g., where applicable) being larger than the bushing

260 (e.g., larger than the portion 264). In accordance with these and other examples, such a degree of freedom may facilitate the insertion of the fastener 210, compared with other techniques that do not support such degrees of freedom (e.g., where aspects of a first subassembly and a second subassembly may be over-constrained or non-concentric).

[0035] Coupling of the first subassembly with the second subassembly may continue by engaging the threaded portion 215 of the fastener 210 with the threaded portion 265 of the bushing 260 by translating the fastener 210 into the bushing 260 (e.g., along the axis 211) and rotating the fastener 210 (e.g., about the axis 211). Rotation of the bushing 260 about the axis

261 may be suppressed by contact between the interface 266 of the bushing 260 and the interface 257 of the bushing 250. Engaging the threaded portions may establish a tensile preload in the fastener 210 which may be reacted as a compressive preload among or between other components of the fastening system 150-d and the subassemblies. For example, a compressive preload may be established between the head portion 216 of the fastener 210 and the bushing 220, and between the bushing 220 and the bushing 230, which may couple (e.g., mate, bring into contact) the interface 223 with the interface 232. As a result of such a coupling of surfaces that are non-perpendicular to the axis 211 (e.g., among other axes along similar directions), a radial constraint may be established between the bushing 220 and the bushing 230 (e.g., between the axis 221 and the axis 231). Similarly, a compressive preload may be established at the bushing 260 (e.g., based on the mating of the threaded portion 215 of the fastener 210 with the threaded portion 265 of the bushing 260, and between the bushing 260 and the bushing 250, which may couple (e.g., mate, bring into contact) the interface 263 with the interface 252. As a result of such a coupling of surfaces that are nonperpendicular to the axis 211 (e.g., among other axes along similar directions), a radial constraint may be established between the bushing 260 and the bushing 250 (e.g., between the axis 261 and the axis 251). Therefore, based on the preloading provided by the fastener 210 (e.g., corresponding to an assembled condition of the fastening system 150-d), a radial constraint may be established between the first subassembly and the second subassembly (e.g., at a coupling location of a corresponding assembly, such as an assembly 100), based on the collection of radial constraints established between the first subassembly and the fastening system 150-d, between the second subassembly and the fastening system 150-d, and between components of the fastening system 150-d themselves.

[0036] FIG. 3 illustrates an example of the fastening system 150-d in an assembled condition. In the assembled condition of the fastening system 150-d (e.g., corresponding to at least a partially assembled condition of a first subassembly and a second subassembly), the fastener 210 may be configured to maintain a preload between the bushing 220, hidden inside the bushing 250 in the view of FIG. 3, and the bushing 260 (e.g., along an axis 211, associated with a tensile load of the fastener 210 reacted via at least a compressive load of the bushing 220 and a compressive load of the bushing 260). Such a preload may support the fastening system 150-d establishing one or more constraints (e.g., at least a radial constraint) between the first subassembly and the second subassembly (e.g., in the assembled condition).

[0037] The preload of the fastener 210 may be reacted by various components of the fastening system 150-d, of one or both of the coupled subassemblies, or various combinations thereof. In some examples, at least a portion of the preload may be reacted via the bushing 220 and the bushing 230, and the bushing 230 may impose the conveyed preload on a first projection 130 of the second subassembly (e.g., via an interface 234, via a flange interface). Similarly at least a portion of the preload may be reacted via the bushing 260 and the bushing 250, and the bushing 250 may impose the conveyed preload on a second projection 130 of the second subassembly (e.g., via an interface 254, via a flange interface). In such examples, the conveyed preload may be imposed at least in part as a bending load on each of the projections 130, which may be reacted between the projections 130 via a physical coupling of the second subassembly between the projections 130. In some examples, such a bending load may be associated with a bending deflection of the projections 130, and an associated deflection of the projections 130 (e.g., associated with an angular misalignment between the bushing 230 and the bushing 250) may be accommodated by spherical interfaces of the fastening system 150-d (e.g., by mating spherical surfaces of an interface 223 and an interface 232, by mating spherical surfaces of an interface 263 and an interface 252). In some examples, such an accommodation may reduce a bending load imposed on the fastener 210 resulting from the generated preload. In some examples (e.g., for cases in which the preload of the fastener 210 is reacted entirely via projections 130), the fastening system 150-d may be associated with an axial degree of freedom (e.g., a translational degree of freedom, along the axis 241) between the first subassembly and the second subassembly (e.g., associated with a separation between the bearing 240 and one or both of the bushing 230 or the first projection 130, associated with a separation between the bearing 240 and one or both of the bushing 250 or the second projection 130).

[0038] Additionally, or alternatively, in some examples, at least a portion of the preload may be reacted via a bearing 240. For example, a bushing 230, a bushing 250, or both may be in contact with an inner portion of the bearing 240 (e.g., an inner race, a portion of the bearing 240 associated with an interface 242), and such an inner portion of the bearing 240 may convey at least a portion of the preload as a compressive load in a direction along an axis 241. In some such examples, the bearing 240 may be associated with providing an axial constraint (e.g., a translational constraint, along the axis 241) between the first subassembly and the second subassembly. Some such examples may include omitting an interface 234, an interface 254, or both, such that a preload of the fastener 210 may be reacted entirely via the bearing 240.

[0039] Thus, in accordance with these and other implementations in accordance with examples as disclosed herein, a fastening system 150 may be configured with various interfaces (e.g., physical interfaces, mating interfaces, surfaces). The fastening system 150 may support one or more degrees of freedom between subassemblies during assembly or disassembly operations and support one or more constraints between subassemblies in an assembled condition. By supporting one or more degrees of freedom during assembly or disassembly operations and one or more constraints in an assembled condition, fastening systems 150 in accordance with examples as disclosed herein may support improved assembly or disassembly operations while also supporting relatively precise positioning between subassemblies. For example, a fastening system 150 may be configured with interfaces that provide one or more radial degrees of freedom, during an assembly or disassembly operation, that facilitate an insertion or removal of a fastener 210 despite any misalignment or overconstraint between subassemblies, and that provide one or more radial constraints, for an as-assembled condition, that support a precise relative positioning between subassemblies in the as-assembled condition.

[0040] FIG. 4 illustrates an example of an assembly 100-a that supports techniques for positioning precision between subassemblies in accordance with examples as disclosed herein. The assembly 100-a includes a subassembly 105-a and a subassembly 110-a, which may be examples of a subassembly 105 and a subassembly 110 as described herein (e.g., with reference to FIG. 1). The subassembly 105-a and the subassembly 110-a may be coupled with one another at coupling locations 120 (e.g., a coupling location 120-e, a coupling location 120-f, and a coupling location 120-g). Aspects of FIG. 4 may be illustrative of an assembled condition of the assembly 100-a, which may be associated with an assembled condition of a set of fastening systems 150-d (e.g., fastening system 150-d-l at the coupling location 120-e, fastening system 150-d-2 at the coupling location 120-f, fastening system 150-d-3 at the coupling location 120-g). In the example of FIG. 4, the assembly 100-a is illustrated in accordance with a cross-sectional view through fastening system 150-d-l and fastening system 150-d-2, providing a view of interfaces of the fastening system 150-d-l and the fastening system 150-d-2 as coupled in the assembled condition.

[0041] Assembling the subassembly 105-a with the subassembly 110-a may be supported in accordance with various step- wise assembly operations of the fastening systems 150-d, which may be supported by one or more degrees of freedom during various assembly operations. For example, the subassembly 105-a and the subassembly 110-a may be positioned in an orientation that supports installing the fastening system 150-d-l and the fastening system 150-d-2, which may or may not correspond to an orientation in which coupling locations of the subassembly 105-a and the subassembly 110-a associated with the coupling location 120-g are aligned (e.g., a positioning that may or may not support the installation of the fastening system 150-d-3). For the coupling locations 120-e and 120-f (e.g., for the fastening systems 150-d-l and 150-d-2, respectively) a respective fastener (e.g., a fastener 210 of FIG. 3) may be inserted (e.g., as supported by various radial degrees of freedom as described herein), and then tightened into a respective bushing (e.g., a bushing 260 of FIG. 3), which may establish various constraints as described herein. For example, tightening a fastener 210 for the fastening system 150-d-l may support establishing a radial constraint between the projection 125-e and one or both of the projection 130-e-l and the projection 130-e-2, and tightening a fastener 210 for the fastening system 150-d-2 may support establishing a radial constraint between the projection 125-f and one or both of the projection 130-f-l and the projection 130-f-2.

[0042] The installation of the fastening system 150-d-l and the fastening system 150-d-2 may establish various constraints and degrees of freedom between the subassembly 105-a and the subassembly 110-a. For example, the radial constraints associated with the fastening system 150-d-l and the fastening system 150-d-2 may establish a radial constraint, between the subassembly 105-a and the subassembly 110-a, relative to an axis 410. The axis 410 may be aligned along a respective axis 211 of each of the fastening systems 150-d-l and 150-d-2 (e.g., an axis 211 with reference to FIG. 2), or aligned along such axes 211 within a tolerance. In some examples, installation of the fastening system 150-d-l and the fastening system 150-d-2 may be associated with a translational degree of freedom between the subassembly 105-a and the subassembly 110-a (e.g., an axial degree of freedom, a degree of freedom along a direction of the axis 410), including circumstances in which a clearance exists between the projection 125-e and both the projections 130-e-l and 130-e-2, and between the projection 125-f and both the projections 130-f-l and 130-f-2 (e.g., along a direction of the axis 410), among other clearances. In some other examples, installation of the fastening system 150-d-l and the fastening system 150-d-2 may be associated with a translational constraint between the subassembly 105-a and the subassembly 110-a (e.g., an axial constraint, a constraint along a direction of the axis 410), including circumstances in which the projection 125-e is loaded in contact with one or both of the projections 130-e-l and 130-e-2, or in which the projection 125-f is loaded in contact with one or both of the projections 130-f-l and 130-f-2, or in which one or more bushings (e.g., one or more bushings 230 or 250 with reference to FIG. 3) are loaded in contact with a bearing (e.g., a bearing 240 with reference to FIG. 3), among other contact loading.

[0043] In some examples, installation of the fastening system 150-d-l and the fastening system 150-d-2 may be associated with a rotational degree of freedom between the subassembly 105-a and the subassembly 110-a, such as a rotational degree of freedom about the axis 410. Such a rotational degree of freedom may be supported by various rotational degrees of freedom of the fastening systems 150-d-l and 150-d-2 (e.g., supported by various rotation of components or interfaces about a respective axis 211). In some examples, such a rotational degree of freedom may support aspects of assembly or disassembly of the assembly 100-a. For example, after installing the fastening systems 150-d-l and 150-d-2, the subassembly 110-a may be rotated relative to the subassembly 105-a about the axis 410 to bring the projections 130-g-l and 130-g-2 into position relative to the projection 125-g, thereby supporting the installation of the fastening system 150-d-3 at the coupling location 120-g. For example, in such a position, for the fastening system 150-d-3, a respective fastener 210 may be inserted (e.g., as supported by various radial degrees of freedom as described herein), and then tightened into a respective bushing 260, which may further establish various constraints as described herein (e.g., with reference to the fastener 210 and the bushing 260 of FIG. 3).

[0044] With the combination of radial constraints provided by the fastening systems 150-d-l, 150-d-2, and 150-d-3, the subassembly 105-a and the subassembly 110-a may be coupled with at least a planar constraint, such that rotations between the subassembly 105-a and the subassembly 110-a may be suppressed (e.g., prevented) about any axis, and translations between the subassembly 105-a and the subassembly 110-a may be suppressed (e.g., prevented) along any direction perpendicular to the axis 410. In various examples, the assembly 100-a may also include a translational constraint between the subassembly 105-a and the subassembly 110-a along a direction of the axis 410, or the assembly 100-a may include a limited translational degree of freedom between the subassembly 105-a and the subassembly 110-a along a direction of the axis 410. In some examples, such as implementations in an antenna system or other system associated with an angular pointing, such a translational degree of freedom along a direction of the axis 410 may have limited or negligible effect on positioning tolerance (e.g., pointing tolerance, pointing precision), and may be part of a suitable tradeoff between assembly precision and ease of assembly or disassembly (e.g., where a limited degree of freedom along a direction of the axis 410 may facilitate aspects of assembly or disassembly).

[0045] The features of the fastening systems 150-d may also support aspects of partial or complete disassembly of the assembly 100-a, which may include a disassembly or removal of one or more of the fastening systems 150-d. For example, the fastening system 150-d-3 may be removed, which may support the subassembly 110-a being rotated relative to the subassembly 105-a (e.g., about the axis 410), which may support various maintenance operations associated with the subassembly 110-a. For example, such a rotation of the subassembly 110-a may support maintenance operations being performed on an antenna assembly or other components associated with the subassembly 110-a. A removal of the fastening system 150-d-3 may include a removal of an associated fastener 210, which may be facilitated by radial degrees of freedom supported by the fastening system 150-d-3 when a preload of the associated fastener 210 is removed. For example, by loosening the associated fastener 210, a bushing 220 of the fastening system 150-d-3 may have a radial degree of freedom relative to the subassembly 110-a (e.g., due to a clearance between an interface 223 and the subassembly 110-a or an interface 232 of a bushing 230 coupled with the subassembly 110-a), or a bushing 260 of the fastening system 150-d-3 may have a radial degree of freedom relative to the subassembly 110-a (e.g., due to a clearance between an interface 263 and the subassembly 110-a or an interface 252 of a bushing 250 coupled with the subassembly 110-a), or both. Such radial degrees of freedom may support a radial degree of freedom between the associated fastener 210 of the fastening system 150-d-3 and the subassembly 110-a. Thus, even in the presence of a radial constraint between the associated fastener 210 of the fastening system 150-d-3 and the subassembly 105-a (e.g., via a bearing 240), the associated fastener 210 may be removed freely because the components are not over-constrained at the coupling location 120-g (e.g., due to a misalignment between an axis associated with a coupling location of the subassembly 105-a and an axis associated with a coupling location of the subassembly 110-a. Thus, the associated fastener 210 may be removed more easily than a precision-formed pin from precision-formed holes, where an over-constrained condition between the subassembly 105-a and the subassembly 110-a may be associated with considerable binding that impedes or prevents the removal us such a precision-formed pin). After such maintenance operations, the subassembly 110-a may be rotated (e.g., about the axis 410) back into position, such that the fastening system 150-d-3 may be reinstalled. As a result of the precision radial constraints associated with the fastening systems 150-d, upon reinstallation of the fastening system 150-d-3, the subassembly 110-a may be returned to a same position as before the fastening system 150-d-3 was disassembled (e.g., within a tolerance between the components of the assembly 100-a).Such a reinstallation may again be facilitated by the radial degrees of freedom associated with the fastening system 150-d-3 prior to preloading of the associated fastener 210, which may support freely inserting the associated fastener 210 through the corresponding components.

[0046] Thus, in accordance with these and other implementations in accordance with examples as disclosed herein, a fastening system 150 may be configured with various interfaces (e.g., physical interfaces, mating interfaces, surfaces). The fastening system 150 may support one or more degrees of freedom between subassemblies during assembly or disassembly operations and support one or more constraints between subassemblies in an assembled condition. By supporting one or more degrees of freedom during assembly or disassembly operations and one or more constraints in an assembled condition, fastening systems 150 in accordance with examples as disclosed herein may support improved assembly or disassembly operations while also supporting relatively precise positioning between subassemblies. For example, a fastening system 150 may be configured with interfaces that provide one or more radial degrees of freedom, during an assembly or disassembly operation, that facilitate an insertion or removal of a fastener 210 despite any misalignment or overconstraint between subassemblies, and that provide one or more radial constraints, for an as-assembled condition, that support a precise relative positioning between subassemblies in the as-assembled condition. [0047] FIG. 5 shows a flowchart illustrating a method 500 that supports techniques for positioning precision between subassemblies in accordance with examples as disclosed herein.

[0048] At 505, the method 500 may include inserting a first fastener (e.g., a first fastener 210, a fastener of a first fastening system 150) through a first opening of a first bushing (e.g., an opening of a first bushing 220, an opening associated with a first interface 232), a second opening associated with a first subassembly (e.g., a first opening associated with a subassembly 105, an opening of a first projection 125, an opening of a first bearing 240 associated with an interface 242), and a third opening of a second bushing (e.g., an opening of a first bushing 260, an opening associated with a first interface 262). In some examples, inserting the first fastener may be based at least in part on (e.g., supported by, facilitated by) a radial degree of freedom between the first bushing (e.g., the first bushing 220) and a second subassembly (e.g., a subassembly 110), or a radial degree of freedom between the second bushing (e.g., the first bushing 260) and the second subassembly, or a combination thereof. The operations of 505 may be performed in accordance with examples as disclosed herein.

[0049] At 510, the method may include constraining the first subassembly and the second subassembly in directions radial to an axis (e.g., a first axis 211) of the first fastener based at least in part on preloading (e.g., using the first fastener) a first surface of the first bushing (e.g., an interface 223) with a second surface associated with the second subassembly (e.g., a first surface of the subassembly 110, a surface of a first projection 130, an interface 232) and a third surface of the second bushing (e.g., an interface 263) with a fourth surface associated with the second subassembly (e.g., a second surface of the subassembly 110, a surface of a second projection 130, an interface 252). In some examples, preloading the first surface with the second surface may be associated with (e.g., may impose, may define) a radial constraint between the first bushing and the second subassembly. Additionally, or alternatively, in some examples, preloading the third surface with the fourth surface may be associated with (e.g., may impose, may define) a radial constraint between the second bushing and the second subassembly. The operations of 510 may be performed in accordance with examples as disclosed herein.

[0050] At 515, the method may include inserting a second fastener (e.g., a second fastener 210, a fastener 210 of a second fastening system 150) through a fourth opening of a third bushing (e.g., an opening of a second bushing 220, an opening associated with a second interface 232), a fifth opening associated with the first subassembly (e.g., a second opening associated with the subassembly 105, an opening of a second projection 125, an opening of a second bearing 240 associated with an interface 242), and a sixth opening of a fourth bushing (e.g., an opening of a second bushing 260, an opening associated with a second interface 262). In some examples, inserting the second fastener may be based at least in part on (e.g., supported by, facilitated by) a radial degree of freedom between the third bushing (e.g., the second bushing 220) and the second subassembly, or a radial degree of freedom between the fourth bushing (e.g., the second bushing 260) and the second subassembly, or a combination thereof. The operations of 515 may be performed in accordance with examples as disclosed herein.

[0051] At 520, the method may include constraining the first subassembly and the second subassembly in directions radial to an axis (e.g., a second axis 211) of the second fastener based at least in part on preloading (e.g., using the second fastener) a fifth surface of the third bushing (e.g., an interface 223) with a sixth surface associated with the second subassembly (e.g., a third surface of the subassembly 110, a surface of a third projection 130, an interface 232) and a seventh surface of the fourth bushing (e.g., an interface 263) with an eighth surface associated with the second subassembly (e.g., a fourth surface of the subassembly 110, a surface of a fourth projection 130, an interface 252). In some examples, preloading the fifth surface with the sixth surface may be associated with (e.g., may impose, may define) a radial constraint between the third bushing (e.g., the second bushing 220) and the second subassembly. Additionally, or alternatively, in some examples, preloading the seventh surface with the eighth surface may be associated with (e.g., may impose, may define) a radial constraint between the fourth bushing (e.g., the second bushing 260 and the second subassembly. The operations of 520 may be performed in accordance with examples as disclosed herein.

[0052] In some examples of the method 500, the first surface, the second surface, the third surface, and the fourth surface may be non-perpendicular to the axis of the first fastener and the first surface, the second surface, the third surface, and the fourth surface may be nonperpendicular to the axis of the first fastener.

[0053] Additionally, or alternatively, some examples of the method 500 may further include rotating the second subassembly relative to the first subassembly, after preloading the first surface with the second surface and preloading the third surface with the fourth surface, based at least in part on a rotational degree of freedom between the first subassembly and the second subassembly about the axis of the first fastener (e.g., about an axis 410). [0054] It should be noted that the described methods include possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, portions from two or more of the methods may be combined.

[0055] A system for coupling a first subassembly with a second subassembly is described. The following provides an overview of aspects of the system as described herein:

[0056] The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “exemplary” used herein means “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

[0057] As used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of’ or “one or more of’) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an exemplary step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on.”

[0058] In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[0059] The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.