Ultra-lightweight and ultra-precise portable coordinate measuring machine with a reduced-profile swivel joint

Abstract

A coordinate measuring machine (CMM) may include a manually positionable articulated arm that includes an arm section and a rotary joint. The swivel joint may include two or more bearings, a shaft coupled to the inner races of the first and second bearings, a first housing coupled to the outer race of the first bearing, and a second housing coupled to the outer race of the second bearing. The second housing is not directly connected to the first housing. The swivel joint may also include an inner spacer coupled to the inner races of the first and second bearings and an outer spacer coupled to the outer races of the first and second bearings. Most of the outer surface of the outer spacer may be exposed to form part of the housing of the CMM.

Description

Technical Field

[0001] The present disclosure generally relates to coordinate measuring machines, and more particularly to highly accurate and ultra-lightweight portable coordinate measuring machines.

Background Art

[0002] (Background) Coordinate measuring machines, among other things, serve to measure points in three-dimensional space. Coordinate measuring machines, for example, trace measurement points in a Cartesian coordinate space (x, y, z). Coordinate measuring machines typically consist of a base and a tracing system. The base can serve as a reference point relative to which the tracing system can move in space in a measurable manner. The tracing system for a portable coordinate measuring machine may include an articulated arm attached to the base at one end and a measurement probe at the other end.

[0003] For the measurement to be useful, it must be accurate. However, very high accuracy is difficult to achieve due to factors such as temperature and load conditions. In particular, in portable coordinate measuring machines, the distortion of the arm caused by thermal changes or by changes in load affects the accuracy of the measurement. As a result, from the perspective of their performance, conventional portable coordinate measuring machines lacked accuracy, especially because they lacked rigidity.

[0004] Improvements in accuracy may be available. However, conventionally, such improvements have been accompanied by a significant increase in the mass and / or weight of the coordinate measuring machine. Conventional portable coordinate measuring machines with improved accuracy were bulky and heavy. These are undesirable characteristics for coordinate measuring machines, especially portable coordinate measuring machines. Also, a process for fabricating and assembling joints of a coordinate measuring machine, especially long joints, with the precision required to obtain accurate measurements has not been available.

Summary of the Invention

Means for Solving the Problems

[0005] (Summary of the Invention) The present disclosure provides a portable coordinate measuring machine (CMM) that is more accurate than prior art coordinate measuring machines. Notably, the CMM disclosed herein is also lighter and less bulky.

[0006] In one aspect of the present invention, the CMM disclosed herein includes a novel swivel joint. The swivel joint is installed between bearings to maintain an appropriate spacing therebetween and, more importantly, to set and retain a preload that improves rigidity, and thus measurement accuracy, as compared to, for example, self-weight preload or spring preload. The swivel joint may include spacers. An outer spacer may be disposed in contact with the outer race of the first bearing and the outer race of the second bearing, and an inner spacer may be disposed in contact with the inner race of the first bearing and the inner race of the second bearing. Most of the outer surface of the outer spacer may be exposed so as to represent at least one outermost layer of the swivel joint. That is, most of the outer surface of the outer spacer may be exposed so as to form part of the housing of the CMM. Compared to conventional CMMs, the swivel joint disclosed herein is significantly smaller, lighter (and thus easier to transport), and aesthetically superior (since there is no need for any additional housing components). This swivel joint design is also more rigid, which can reduce flexure or deformation of the CMM and thus improve the accuracy of the CMM.

[0007] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments of aspects of the invention and illustrate various exemplary systems, methods, etc. It should be understood that the element boundaries shown in the figures (e.g., boxes, groups of boxes, or other shapes) represent one example of a boundary. One of ordinary skill in the art will understand that one element may be designed as multiple elements, or multiple elements may be designed as one element. An element shown as an internal component of another element may be implemented as an external component, and vice versa. Further, the elements may not be drawn to scale.

Brief Description of the Drawings

[0008]

Figure 1A

Figure 1B

Figure 1C

Figure 1D

[0009]

Figure 2A

Figure 2B

[0010]

Figure 3A

Figure 3B

[0011]

Figure 4A

Figure 4B

[0012]

Figure 5A

Figure 5B

Figure 5C

DETAILED DESCRIPTION

[0013] (Detailed Description) FIGS. 1A - 1C illustrate a perspective view of an exemplary coordinate measuring machine (CMM) 1. FIG. 1D illustrates a cross-sectional view of the exemplary CMM 1. The CMM 1 includes an articulated arm 2, a base 4, and a measurement probe 6. The articulated arm 2 is attached to the base 4 at one end and to the measurement probe 6 at the other end. The base 4 may be attached to, for example, a base plate 5 to attach the arm 2 to, for example, a work surface. The articulated arm 2 includes two arm sections 8, 9 and several rotary joints 12, 14, 16, 18, 20, 22, 24.

[0014] The overall length of the articulated arm 2 and / or the arm sections 8, 9 may vary depending on its intended use. In one embodiment, the articulated arm may have an overall length of about 48 inches. This arm dimension provides a portable CMM that is currently very suitable for measurements performed using typical hand tools such as micrometers, height gauges, calipers, and the like. The articulated arm 2 may have smaller or larger dimensions.

[0015] The rotary joints generally include two types of joints, namely, swivel joints 12, 16, 20 and hinge joints 14, 18, 22. The swivel joints 12, 16, 20 are positioned generally along the substantially axial or longitudinal direction along the arm 2. The hinge joints 14, 18, 22 are generally positioned at 90° to the swivel joints or at 90° to the longitudinal axis of the arm 2. The swivel and hinge joints are generally mated as shown in FIGS. 1A-1D, although the joints may be arranged in other configurations. For the plurality of rotary joints, the arm 2 is manually positionable, meaning that the user can freely manually move the probe 6 to any position within the radius substantially tethered to the base 4 of the CMM 1. Each of these joints is generally shown in FIGS. 2A-5C.

[0016] Generally, the base plate 5 of the base 4 attaches the CMM 1 to the work surface, and the base 4 is attached to the swivel joint 12, which is attached to the hinge joint 14, which is attached to the swivel joint 16, which is attached to the hinge joint 18, which is attached to the swivel joint 20, which is attached to the hinge joint 22, which is attached to the measuring probe 6.

[0017] FIG. 2A illustrates a partial cross-sectional view of the swivel joint 16, while FIG. 2B illustrates a partial exploded view of an exemplary swivel joint 16. Each of the figures illustrates only the end of the swivel joint 16, and the central portion of the swivel joint not shown corresponds to the arm section 8. The swivel joint 16 will generally be used to explain the swivel joints 12, 16, 20 even if the swivel joints are not the same. The swivel joints 16 and 20 are very similar.

[0018] The swivel joint 16 may include housings 48, 49, a shaft 30, bearings 32, 34, spacers 301a, 301b, an encoder PCB 36, an encoder disk 38, and a slip ring 40. The bearings 32, 34 are preferably steel or stainless steel ball bearings. The relatively long shaft 30 may be processed from a material that is rigid like that from steel, such as carbon fiber, aluminum, etc., but is relatively lightweight. In one embodiment, the shaft 30 may be processed from steel or ceramic so as to match the material from which the bearings 32, 34 are processed. Similar to the relatively long shaft 30, the spacers 301a, 301b may be tubes processed from a material that has the same rigidity as the shaft 30, including those from carbon fiber, ceramic, or steel, but is relatively lightweight.

[0019] At one end of the swivel joint 16, the housing 48 has a port in which an end of the shaft 30 resides, and a yoke 48a that operably connects the swivel joint 16 to the aforementioned hinge joint (see FIGS. 1A - 1D). In the case of the swivel joint 16, the yoke 48a has two protrusions that connect the swivel joint 16 to the shaft of the hinge joint 14. At the other end of the swivel joint 16, the housing 49 has a port in which an end of the shaft 30 resides.

[0020] As can be seen in most detail in FIG. 2A, at one end of the swivel joint 16, the inner diameter of the port of the housing 48 engages (e.g., is fixedly attached to) the outer diameter or outer race of the bearing 32. The port of the housing 48 may be glued, for example, to the outer diameter or outer race of the bearing 32. The shaft 30 has an outer diameter that engages (e.g., is fixedly attached to) the inner diameter or inner race of the bearing 32 over a portion of it. The shaft 30 may be glued, for example, to the inner diameter or inner race of the bearing 32. At the other end of the swivel joint 16, the inner diameter of the port of the housing 49 engages (e.g., is fixedly attached to) the outer diameter or outer race of the bearing 34. The port of the housing 49 may be glued, for example, to the outer diameter or outer race of the bearing 34. The shaft 30 has an outer diameter that engages (e.g., is fixedly attached to) the inner diameter or inner race of the bearing 34 over a portion of it. The shaft 30 may be glued, for example, to the inner diameter or inner race of the bearing 34. The shaft 30 thus rotates about the axis of rotation a of the bearings 32 and 34 and the housings 48 and 49.

[0021] The PCB 36 of the swivel joint 16 has at least one transducer laid thereon configured to output an angle signal corresponding to the rotational angle of the shaft 30 with respect to the housings 48, 49 about the axis of rotation α. Each transducer comprises an optical encoder having two primary components, namely, one or more read heads and an encoder disk 38. The encoder disk 38 is operably attached (e.g., using fasteners and / or a suitable adhesive) to the end of the shaft 30 spaced from and aligned with the read head of the PCB 36, which is operably attached (e.g., using a suitable adhesive) to the housing 48. The locations of the disk 38 and the read head may be reversed, whereby the disk 38 may be operably attached to the housing 48 and the read heads rotate in tandem with the shaft 30 such that they are rotatable relative to each other while maintaining optical communication. The encoder is commercially available from Celera Motion, for example, under the trade name MicroE encoder, etc. Each PCB 36 may additionally include a processor for receiving the angle signal from the read head and a transceiver and connector for connecting the PCB 36 to the communication bus of the CMM 1 and / or other wiring. Each of the PCBs 36 may also include a temperature sensor connected to the processor to provide thermal compensation due to room temperature variations.

[0022] A Kapton film 306 may be positioned between the PCB 36 and the housing 48 for electrical insulation. A plastic cap 307 may be glued to the central hole of the PCB 36 to seal the cavity between the PCB 36 and the encoder disk 38 and protect against dust contamination.

[0023] The cover 82 is operably attached to the housing 48, covers the wiring harness, and seals the PCB 36 and the encoder disk 38 from dust contamination. The cover 82 may be integral or divided into two parts 82a and 82b that are operably attached to the housing 48. The cover part 82b has a portion that covers a part of the yoke 48a that projects to operably connect the swivel joint 16 to the hinge joint 14.

[0024] (Similar to other joints within CMM1), the swivel joint 16 can have infinite rotation, meaning that it can rotate 360° about its axis of rotation α. Accordingly, a slip ring 40 is used to provide an infinitely rotatable electrical connection to the swivel joint 16. Shafts used herein within swivel joints, such as shaft 30 of base swivel joint 12 and shaft 30 of swivel joint 16, may be hollow (i.e., have an axial opening). Shafts used herein within hinge joints, such as shaft 80 of hinge joint 18 described below, may also be hollow and may include an opening (see FIG. 3A).

[0025] The swivel joint 16 of the arm section 8 is a relatively long joint, as can be understood from FIGS. 1A-1D. In one embodiment, the shaft 30 is at least 6 inches in length. Such long joints have been problematic in the past because, as detailed in U.S. Patent No. 10,267,614 (incorporated herein by reference in its entirety), improved accuracy required concentricity between bearing bores within housings 48 and 49. The prior art (e.g., U.S. Patent No. 10,267,614, see FIG. 3C) used special fixtures to align those bores for improved concentricity. This process was cumbersome and left room for further concentricity improvement. Also, the prior art (e.g., U.S. Patent No. 10,267,614, see FIG. 3E) used self-weight or spring washers to apply bearing preload, which also left room for further improvement. The swivel joint 16 uses a novel and unique configuration to address these problems.

[0026] The Cardan joint 16 may include spacers 301a, 301b that can serve as a spacer (involved in maintaining an appropriate distance and preload between the bearings 32, 34) and as the housing or outermost layer of the CMM1 for the unique configuration of the Cardan joint 16. This unique design solves the concentricity problems in the prior art as it provides a rigid and concentric Cardan joint bearing assembly that incorporates the bearings 32, 34 and the spacers 301. The unique design with the spacers 301 also provides an improvement in bearing preload.

[0027] In the illustrated embodiment, the inner spacer 301a is a tubular spacer that is disposed in contact with the inner races of the first bearing 32 and the second bearing 34, while the outer spacer 301b is a tubular spacer that is disposed in contact with the outer races of the first bearing 32 and the second bearing 34. The spacers 301a and 301b are matched and precisely lapped to maximize the accuracy of the structure formed by the spacers 301a, 301b, and the bearings 32, 34. Also, as shown in FIG. 2A, most of the outer surface of the outer spacer 301b is exposed (i.e., there is no additional cladding over the spacer 301b), and thus, the outer surface of the outer spacer 301b is the outermost layer of the Cardan joint 16. This means that the outer surface of the outer spacer 301b forms part of the housing of the CMM1.

[0028] Since the outer surface of the outer spacer 301b is part of the housing of the CMM1, no additional fixture application is necessary. In addition, the spacers 301a and 301b add stiffness to the Cardan joint bearing assembly of the CMM1 compared to conventional CMMs, which reduces bending / flexure and thus increases stiffness and ultimately accuracy. In part, due to this unique design, the CMM1 achieves significantly better accuracy than prior art portable coordinate measuring machines.

[0029] FIG. 3A illustrates a cross-sectional view of the hinge joint 18, while FIG. 3B illustrates an exploded view of an exemplary hinge joint 18. The hinge joint 18 will generally be used here to describe the hinge joints 14, 18, 22, even if the hinge joints may not be the same. At least some of the components of the hinge joint 18 are substantially similar to the components discussed in detail above with reference to the swivel joints 12 and 16, and thus these similar components are identified in FIGS. 3A and 3B using the same reference indicators as in the foregoing figures.

[0030] The hinge joint 18 may include a housing 78, a shaft 80, bearings 32, 34, spacers 301a, 301b, an encoder PCB 36, and an encoder disk 38. As can be seen most clearly in FIG. 3A, the housing 78 has ports that engage (e.g., are fixedly attached to) the outer diameters or outer races of the bearings 32, 34. The ports of the housing 78 may be glued, for example, to the outer diameters or outer races of the bearings 32 and 34. The shaft 80 has an outer diameter that engages (e.g., is fixedly attached to) the inner diameters or inner races of the bearings 32, 34 over a portion thereof. The shaft 80 may be glued, for example, to the inner diameters or inner races of the bearings 32, 34. The shaft 80 thus rotates about the rotation axis b of the bearings 32, 34 of the hinge joint 18 and the housing 78.

[0031] The spacers 301a, 301b may be tubes that are of the same stiffness as the shaft 80, including those made from carbon fiber, ceramic, or steel, but are further processed from a relatively lightweight material. The spacers 301a, 301b may be installed between the bearings 32, 34 to maintain an appropriate interval therebetween, and more importantly, to set and maintain a preload. In the illustrated embodiment, the inner spacer 301a is a tubular spacer that is disposed in contact with the inner race of the first bearing 32 and the inner race of the second bearing 34, while the outer spacer 301b is a tubular spacer that is disposed in contact with the outer race of the first bearing 32 and the outer race of the second bearing 34. The spacers 301a and 301b are matched to maximize the accuracy of the structure formed by the spacers 301a, 301b, and the bearings 32, 34, and are precisely lapped and finished.

[0032] The shaft 80 is configured to engage with the yokes of adjacent swivel joints, such as the yoke 48a of the swivel joint 20. In the illustrated embodiment, the shaft 80 has a groove 72 that is machined or otherwise formed thereon to create a gap (e.g., 5 mils or 127 μm) for better bonding of the adhesive with the yokes of adjacent swivel joints, such as the yoke 48a of the swivel joint 16. The housing 78 has a housing bracket 78a constructed, welded, or otherwise disposed thereon to create a gap 79 in the housing 78 for one of the protruding portions of the yoke to engage with the shaft 80 such that the two protruding portions of the yoke straddle the bearings 32, 34 therebetween.

[0033] The encoder cavity dust seal washer 302 is held in place by a washer 303 that is glued to the inside of the bracket 78a and the shaft 80. A plastic cap 307 is glued to the central hole of the encoder substrate 36. The dust seal washer 302 and the plastic cap 307 seal the encoder cavity from dust contaminants from each end.

[0034] Similar to the swivel joint discussed above, the PCB 36 of the hinge joint 18 is configured to output an angular signal corresponding to the rotation angle of the shaft 80 relative to the housing 78 about the axis of rotation b, and has disposed thereon at least one transducer. As discussed above, each transducer comprises an optical encoder having two primary components, namely, one or more reading heads and an encoder disk 38. In the illustrated embodiment, the encoder disk 38 is operatively attached (e.g., using fasteners and / or a suitable adhesive) to the end of the shaft 80 that is spaced from and aligned with the reading head on the PCB 36, which is operatively attached (e.g., using a suitable adhesive) to the housing 78. The locations of the disk 38 and the reading head may be reversed, such that the disk 38 is operatively attached to the housing 78 and the reading head is rotatable relative to each other while maintaining optical communication and is co-rotatable with the shaft 80. As best shown in FIG. 3A, the PCB 36 and the encoder disk 38 are located adjacent to the end of the shaft 80 that is separated from the bearing 34 by a gap 79. This is different from prior art hinge joints (e.g., see U.S. Patent No. 11,287,241, FIG. 16D), where the PCB 36 and the encoder disk 38 may reside between the ends of the shaft 80 between the bearings 32, 34. In the illustrated embodiment, the PCB 36 and the encoder disk 38 are located outside the yoke of the adjacent swivel joint, rather than between the bearings 32, 34, and are separated from the bearing 34 by a gap 79 such that one of the protrusions of the yoke engages the shaft 80.

[0035] Instead of being inside the housing 78 between the bearings 32, 34, the PCB 36 and the encoder disk 38, which are located near the end of the shaft 80, may be exposed to an external load such as a user who can place the encoder disk 38, the reading head, etc. on, for example, his hand on the joint 18, specifically, the plastic cover 82. This can result in an angular measurement error. To protect against such external loads, the joint 18 may also include a bracket 305 that can be machined from aluminum, steel, etc. and mounted on the housing 78. As shown in FIG. 3B, the housing 78 may have a threaded hole 78b formed thereon to match the holes in the protective bracket 305 so that the bracket 305 can be mounted on the housing 78 using screws. As seen in FIG. 3A, the bracket 305 protects the PCB 36 and the encoder disk 38 from external loads. The joint 18 may further include a cover 82 that is operably attached to the housing 78, covers the wiring harness, and seals the PCB 36 and the encoder disk 38 from dust. The cover 82 may have threaded holes formed thereon to match the threaded holes in the bracket 305 so that the cover 82 can be attached to the bracket 305 using screws.

[0036] Unlike the prior art hinge joint where the electronic device is embedded inside the structural element of the CMM joint (see, e.g., U.S. Patent No. 11,287,241, Figure 16D), for the hinge joint 18, specifically, the PCB 36 and other electronic devices (e.g., wiring harness) can be easily serviced by removing the cover 82. Compared with the prior art CMM, the hinge joint 18 is significantly smaller, lighter, easier to transport, and aesthetically superior because there is no need for any space to fit the encoder PCB 36 between the bearings 32, 34. This design allows for the use of the spacer 301 within the hinge joint 18 compared to the prior art (see, e.g., U.S. Patent No. 10,267,614, Figure 5B) where the applied bearing preload deforms the yoke and misaligns the outer races of the bearings 32 and 34. As a result, the hinge joint 18 becomes more rigid, which can reduce flexure or deformation and thus improve the measurement accuracy of the CMM.

[0037] Figures 4A and 4B illustrate cross-sectional and exploded views of the exemplary joint 12 and the base plate 204. The base plate 204 may have holes 208 formed thereon for receiving fasteners for mounting the CMM 1 to a mounting surface or a magnet plate. The main PCB 158 may be disposed inside the base plate 204. The base plate 204 may have a cover plate 210 that attaches the base plate 204 for covering the opening to a cavity in which the PCB 158 resides. The cover plate 210 may be fastened to the base plate 204 using, for example, screws 212. The main PCB may also be mounted to the cover plate 210 or the base plate 204 using screws. An insulator 306 (e.g., Kapton film) may be disposed between the PCB 158 and the cover plate 210.

[0038] The swivel joint 12 may include a housing 28, a shaft 30, bearings 32, 34, spacers 301a, 301b, an encoder printed circuit board 36, an encoder disk 38, and a slip ring 40. The shaft 30 may have an internal opening 30a (e.g., 0.5 inches or 12.7 mm in diameter) that houses the slip ring 40. A plastic cap 307 is glued to the center hole of the encoder PCB 36 to seal the encoder cavity from dust contamination. As can be seen most clearly in FIG. 4A, the housing 28 has ports that engage (e.g., are fixedly attached to) the outer diameters or outer races of the bearings 32, 34. The ports of the housing 28 may be glued, for example, to the outer diameters or outer races of the bearings 32 and 34. The shaft 30 has an outer diameter that engages (e.g., is fixedly attached to) the inner diameters or inner races of the bearings 32, 34 over a portion thereof. The shaft 30 may be glued, for example, to the inner diameters or inner races of the bearings 32, 34. The shaft 30 thus rotates about the rotation axis c of the bearings 32, 34 of the hinge joint 12 and the housing 28.

[0039] In the illustrated embodiment, the inner spacer 301a is a tubular spacer that is disposed in contact with the inner races of the first bearing 32 and the second bearing 34, while the outer spacer 301b is a tubular spacer that is disposed in contact with the outer races of the first bearing 32 and the second bearing 34. The spacers 301a and 301b are matched and precision lapped to maximize the accuracy of the structure formed by the spacers 301a, 301b, and the bearings 32, 34. The spacers 301a, 301b may be tubes having the same stiffness as the shaft 30, including those from carbon fiber, ceramic, or steel, but being machined from a relatively lighter material. The spacers 301a, 301b may be installed between the bearings 32, 34 to maintain an appropriate spacing therebetween and, more importantly, to set and maintain a preload.

[0040] Similar to the swivel joint discussed above, the PCB 36 of the swivel joint 12 is provided with at least one transducer configured to output an angular signal corresponding to the rotation angle of the shaft 30 with respect to the housing 28 about the axis of rotation c. The encoder PCB 36 and the encoder disk 38 may be stored parallel to the main PCB 158 within the cavity of the base plate 204. This arrangement is particularly space - efficient and compact. Taller components on the main PCB 158 may be installed near the edge of the main PCB 158 (not vertically overlapping the encoder PCB 36) that is taller.

[0041] Figures 5A - 5C illustrate a cross - sectional view and an exploded view of an exemplary measurement probe 6. The probe 6 includes a housing 126 having an internal space for the housing PCB 130 and a handle 128 (formed from two parts 128a and 128b) having an internal space for the housing PCB 125. The housing 126 is operably coupled to the hinge joint 22 (see FIGS. 1A - 1D) using a yoke 126a.

[0042] The measurement probe 6 may also include a contact trigger probe 308 that is mechanically connected (e.g., screwed) to the housing 126 and electrically connected to the PCB 130. The handle 128 may include two switches, namely, a take switch 131 and a confirm switch 132. The operator may use these switches to take measurements (take switch 131) and confirm the measured values (confirm switch 132) during operation. The handle 128 is generally shaped to resemble a human grasping motion, which is more ergonomic than at least some prior art probes. The handle 128 may also house a switch PCB 134 on which the switches 131 and 132 can be mounted. The switch PCB 134 is electrically coupled to the PCB 125 host component for processing signals from the switches 131 and 132. In one embodiment, the PCB 125 includes a wireless (e.g., Wi-Fi, Bluetooth® etc.) transmitter (instead of an electrical connection to the communication bus of the CMM1) that wirelessly transmits the take and confirm signals associated with the switches 131 and 132 to, for example, a host PC that generally controls the CMM1. The wireless transmission of the take and confirm signals associated with the switches 131 and 132 significantly simplifies the cabling and wiring of the probe 6. The probe 6 may also include a battery 309 for powering the electronics therein.

[0043] The handle 128 is attached to an aluminum block 311 and incorporates two plastic bearings 310 that rotate around the housing 126. A haptic feedback motor 312 is glued inside the handle 128 to provide feedback to the operator when taking measurements.

[0044] (Definition) The following includes definitions of selected terms employed in this specification. The definitions cover the scope of the terms and include components of various embodiments or forms that may be used for implementation. The examples are not intended to be limiting. Both singular and plural terms may be within the definitions.

[0045] As used herein, an "operable connection" or "operable coupling", i.e., a connection by which entities are "operably connected" or "operably coupled", is one in which the entities are connected in such a way that the entities can perform as intended. An operable connection can be a direct connection, or an indirect connection where intermediate entity or entities cooperate, or are otherwise part of the connection, or exist between operably connected entities. In the context of signals, an "operable connection", i.e., a connection by which an entity is "operably connected", is one by which a signal, physical communication, or logical communication can be transmitted or received. Typically, an operable connection includes a physical interface, an electrical interface, or a data interface, but note that an operable connection can include different combinations of these or other types of connections sufficient to enable operable control. For example, two entities can be operably connected by being able to communicate signals with each other directly or through one or more intermediate entities such as a processor, an operating system, logic, software, or other entities. A logical or physical communication channel can be used to create an operable connection.

[0046] As used herein, "signal" includes, but is not limited to, one or more electrical or optical signals, analog or digital signals, data, one or more computer or processor instructions, messages, bits or bitstreams, or other means that can be received, transmitted, or detected.

[0047] As long as the terms "includes" or "including" are used in the detailed description or claims, this is intended to be inclusive in a manner similar to the term "comprising" as it is interpreted when used as a transitional term in a claim. Further, as long as the term "or" is used in the detailed description or claims (e.g., "A or B"), this is intended to mean "A or B or both." When the Applicants intend to indicate "only A or B but not both," the term "only A or B but not both" will be employed. Accordingly, the use of the term "or" in this specification is an inclusive and not an exclusive use. See Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d. Ed. 1995). Exemplary systems, methods, etc. are illustrated by way of examples, and the examples are described in considerable detail, but it is not the intention of the Applicants to limit the scope to such detail or to limit it in any way. Of course, it is not possible to describe every conceivable combination of components or methodologies for the purpose of describing the systems, methods, etc. described herein. Additional advantages and modifications will readily occur to those skilled in the art. Accordingly, the invention is not limited to the specific details, representative devices, and illustrative examples shown and described. Thus, this application is intended to cover modifications, adaptations, and variations that fall within the scope of the appended claims. Further, the foregoing description is not intended to limit the scope of the invention. Rather, the scope of the invention should be determined by the appended claims and their equivalents.

Claims

1. A coordinate measuring machine (CMM), The CMM comprises a manually positionable articulated arm having a first end and a second end, the articulated arm comprising a plurality of arm sections and a plurality of rotary joints, the first end comprising a connector configured to connect to a measuring probe, and the second end comprising a base for mounting the CMM on a mounting surface. At least one of the plurality of rotary joints is A first bearing and a second bearing, A shaft for engaging the inner race of the first bearing and the inner race of the second bearing, wherein the shaft is configured to rotate about the rotation axes of the first bearing and the second bearing, and the shaft has two ends, each end configured to engage with one of two projections of the yoke of another adjacent rotary joint among the plurality of rotary joints, thereby the two projections of the yoke straddle the first bearing and the second bearing between them, and the shaft, A housing that engages the outer race of the first bearing with the outer race of the second bearing, An outer tubular spacer is disposed to abut against the outer race of the first bearing and the outer race of the second bearing, and an inner tubular spacer is disposed to abut against the inner race of the first bearing and the inner race of the second bearing, At least one transducer configured to output an angle signal corresponding to the rotation angle of the shaft relative to the housing about the rotation axis, wherein the at least one transducer is positioned adjacent to one of the two ends of the shaft, and is not located between the first bearing and the second bearing. CMM, including.

2. The CMM according to claim 1, wherein the shaft has two grooves formed thereon, each groove being formed adjacent to each of the two ends and configured to engage with each of the two protrusions of the yoke.

3. At least one of the plurality of rotary joints is A printed circuit board (PCB) assembly wherein the at least one transducer is disposed on the PCB assembly, and the PCB assembly is positioned adjacent to one of the two ends of the shaft, so as not to be between the first bearing and the second bearing. The CMM according to claim 1, comprising:

4. At least one of the plurality of rotary joints is An L-shaped mounting bracket, wherein the L-shaped mounting bracket is operably coupled to the housing and the PCB assembly is mounted on it. The CMM according to claim 3, comprising:

5. At least one of the plurality of rotary joints is A protective bracket, wherein the protective bracket is operably coupled to the housing and mounted across the L-shaped mounting bracket, thereby protecting the PCB assembly from external loads. The CMM according to claim 4, comprising:

6. At least one of the plurality of rotary joints is A plastic cover, wherein the plastic cover is mounted across the protective bracket so as to cover the protective bracket and the PCB assembly. The CMM according to claim 5, comprising:

7. A coordinate measuring machine (CMM), The CMM comprises a manually positionable articulated arm having a first end and a second end, the articulated arm comprising a plurality of arm sections and a plurality of rotary joints, the first end comprising a connector configured to connect to a measuring probe, and the second end comprising a base for mounting the CMM on a mounting surface. At least one of the plurality of rotary joints is A first bearing and a second bearing, A shaft for engaging the inner race of the first bearing and the inner race of the second bearing, wherein the shaft is configured to rotate about the rotation axes of the first bearing and the second bearing, and the shaft has two ends, each end configured to engage with a projection of one of two projections of a yoke that connects at least one of the plurality of rotary joints to another adjacent rotary joint among the plurality of rotary joints, thereby the two projections of the yoke straddle the first bearing and the second bearing between them, and the shaft, A housing that engages the outer race of the first bearing with the outer race of the second bearing, At least one transducer configured to output an angle signal corresponding to the rotation angle of the shaft relative to the housing about the rotation axis, wherein the at least one transducer is positioned adjacent to one of the two ends of the shaft such that the at least one transducer is positioned outside the yoke. CMM, including.

8. The CMM according to claim 7, wherein the shaft has two grooves formed thereon, each groove being formed adjacent to each of the two ends and configured to engage with each of the two protrusions of the yoke.

9. At least one of the plurality of rotary joints is An outer tubular spacer is positioned to contact the outer race of the first bearing and the outer race of the second bearing, An inner tubular spacer is positioned to contact the inner race of the first bearing and the inner race of the second bearing. The CMM according to claim 7, comprising:

10. At least one of the plurality of rotary joints is A printed circuit board (PCB) assembly wherein the at least one transducer is disposed on the PCB assembly, and the PCB assembly is positioned adjacent to one of the two ends of the shaft, so as not to be between the first bearing and the second bearing. The CMM according to claim 7, comprising:

11. At least one of the plurality of rotary joints is An L-shaped mounting bracket, wherein the L-shaped mounting bracket is operably coupled to the housing and the PCB assembly is mounted on it. The CMM according to claim 10, comprising:

12. At least one of the plurality of rotary joints is A protective bracket, wherein the protective bracket is operably coupled to the housing and mounted across the L-shaped mounting bracket, thereby protecting the PCB assembly from external loads. The CMM according to claim 11, comprising:

13. At least one of the plurality of rotary joints is A plastic cover, wherein the plastic cover is mounted across the protective bracket so as to cover the protective bracket and the PCB assembly. The CMM according to claim 12, comprising:

14. A coordinate measuring machine (CMM), The CMM comprises a manually positionable articulated arm having a first end and a second end, the articulated arm comprising a plurality of arm sections and a plurality of rotary joints, the first end comprising a connector configured to connect to a measuring probe, and the second end comprising a base for mounting the CMM on a mounting surface. At least one of the plurality of rotary joints is A first bearing and a second bearing, A shaft for engaging the inner race of the first bearing and the inner race of the second bearing, wherein the shaft is configured to rotate about the rotation axes of the first bearing and the second bearing, and the shaft has two ends, each end configured to engage with one of two projections of the yoke of another adjacent rotary joint among the plurality of rotary joints, thereby the two projections of the yoke straddle the first bearing and the second bearing between them, and the shaft, A housing for housing the first bearing and the second bearing, At least one transducer configured to output an angle signal corresponding to the rotation angle of the shaft relative to the housing about the rotation axis, wherein the at least one transducer is positioned adjacent to one of the two ends of the shaft, and is not located between the first bearing and the second bearing. CMM, including.

15. The CMM according to claim 14, wherein the shaft has two grooves formed thereon, each groove being formed adjacent to each of the two ends and configured to engage with each of the two protrusions of the yoke.

16. At least one of the plurality of rotary joints is An outer spacer is positioned to contact the outer race of the first bearing and the outer race of the second bearing, An inner spacer is positioned to contact the inner race of the first bearing and the inner race of the second bearing. The CMM according to claim 14, comprising:

17. At least one of the plurality of rotary joints is A printed circuit board (PCB) assembly wherein the at least one transducer is disposed on the PCB assembly, and the PCB assembly is positioned adjacent to one of the two ends of the shaft, so as not to be between the first bearing and the second bearing. The CMM according to claim 14, comprising:

18. At least one of the plurality of rotary joints is An L-shaped mounting bracket, wherein the L-shaped mounting bracket is operably coupled to the housing and the PCB assembly is mounted on it. The CMM according to claim 17, comprising:

19. At least one of the plurality of rotary joints is A protective bracket, wherein the protective bracket is operably coupled to the housing and mounted across the L-shaped mounting bracket, thereby protecting the PCB assembly from external loads. The CMM according to claim 18, comprising:

20. At least one of the plurality of rotary joints is A plastic cover, wherein the plastic cover is mounted across the protective bracket so as to cover the protective bracket and the PCB assembly. The CMM according to claim 19, comprising:

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