Ultra-lightweight and ultra-accurate portable coordinate measuring machine with reduced external 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 relates generally to coordinate measuring machines, and more specifically, to a highly accurate, ultra-lightweight portable coordinate measuring machine.

Background Art

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

[0003] For a 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, arm distortions caused by thermal changes or by load variations adversely affect measurement accuracy. As a result, in terms of their performance, conventional portable coordinate measuring machines have lacked accuracy, inter alia, 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 properties for coordinate measuring machines, especially portable coordinate measuring machines. Also, no process has been available for organizing and assembling the joints of coordinate measuring machines, particularly long joints, with the precision required to obtain accurate measurements.

Summary of the Invention

Means for Solving the Problems

[0005] (Summary of the invention) This 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 may include spacers installed between bearings to set and preserve a preload, maintaining an appropriate distance between them and, more importantly, to improve rigidity, and therefore measurement accuracy, compared to, for example, a self-weight preload or a spring preload. The outer spacers may be positioned in contact with the outer races of the first and second bearings, and the inner spacers may be positioned in contact with the inner races of the first and second bearings. A large portion of the outer surface of the outer spacers may be exposed to represent the outermost layer of at least one of the swivel joints. That is, a large portion of the outer surface of the outer spacers may be exposed to form part of the housing of the CMM. Compared to conventional CMMs, the swivel joints disclosed herein are significantly smaller, lighter (easier to transport), and aesthetically superior (as there is no need for any additional housing components). This swivel joint design is also more rigid, which can reduce bending or deformation of the CMM and thus improve the accuracy of the CMM.

[0007] The accompanying drawings incorporated herein and forming part thereof illustrate various exemplary systems, methods, etc., illustrating various exemplary embodiments of aspects of the present invention. It should be understood that the element boundaries shown in the drawings (e.g., boxes, groups of boxes, or other shapes) represent one embodiment of the boundary. Those skilled 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. Furthermore, elements may not be drawn to scale. The present invention provides, for example, the following items: (Item 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 including a swivel joint and a hinge joint, 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 swivel joints of the plurality of rotary joints is First and second bearings, A shaft having a length of at least 6 inches and 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, A housing that engages with the outer race of the first bearing, At least one transducer configured to output an angle signal corresponding to the rotation angle of the shaft relative to the housing around the rotation axis, wherein the at least one transducer is positioned adjacent to one of the two ends of the shaft, not between the first bearing and the second bearing. A matching inner and outer tubular spacer set comprising an outer tubular spacer positioned in contact with the outer race of the first bearing and the outer race of the second bearing, and an inner tubular spacer positioned in contact with the inner race of the first bearing and the inner race of the second bearing, wherein the majority of the outer surface of the outer tubular spacer is exposed to represent the at least one outermost layer of the swivel joint; CMM, including. (Item 2) The CMM according to item 1, wherein at least one of the swivel joints comprises a second housing that engages with the outer race of the second bearing, and the second housing is not directly connected to the first housing. (Item 3) The CMM described in item 2, wherein each of the first and second housings extends axially along a longitudinal axis parallel to the rotation axis. (Item 4) The axial lengths of the first housing and the second housing are such that the first housing and the second housing do not cover the majority of the outer surface of the outer tubular spacer, as described in item 3. (Item 5) The CMM according to item 4, wherein the first housing and the second housing are each adhesively bonded to the outer surface of the outer tubular spacer. (Item 6) The inner tubular spacer is bonded to the shaft adhesively, as described in item 1. (Item 7) The CMM according to item 1, wherein the majority of the outer surface of the outer spacer is exposed to form part of the housing of the CMM. (Item 8) 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 rotary joints of the plurality of rotary joints is First and second bearings, A shaft having a length of at least 6 inches, coupled to the inner race of the first bearing and the inner race of the second bearing, and rotating about the axis of rotation of the first bearing and the second bearing, A housing for the first bearing, At least one transducer configured to output an angle signal corresponding to the rotation angle of the shaft relative to the housing around the rotation axis, An outer spacer positioned in contact with the outer race of the first bearing and the outer race of the second bearing, and an inner spacer positioned in contact with the inner race of the first bearing and the inner race of the second bearing, wherein the majority of the outer surface of the outer spacer is exposed to form part of the housing of the CMM, and the outer spacer and inner spacer A CMM is a swivel fitting equipped with [a specific feature]. (Item 9) The swivel joint comprises a second housing that houses the second bearing, and the second housing is not directly connected to the first housing, as described in item 8. (Item 10) The CMM according to item 9, wherein each of the first and second housings extends axially along a longitudinal axis parallel to the rotation axis. (Item 11) The axial lengths of the first housing and the second housing are such that the first housing and the second housing do not cover the majority of the outer surface of the outer spacer, as described in item 10. (Item 12) The CMM according to item 10, wherein the first housing and the second housing are each adhesively bonded to the outer surface of the outer spacer. (Item 13) The inner spacer is bonded to the shaft adhesively, as described in item 8. (Item 14) The CMM according to item 8, wherein the majority of the outer surface of the outer tubular spacer is exposed to represent the outermost layer of at least one of the swivel joints. (Item 15) 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 including a swivel joint and a hinge joint, 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 swivel joints of the plurality of rotary joints is First and second bearings, A shaft is coupled to the inner race of the first bearing and the inner race of the second bearing, and rotates about the rotation axes of the first bearing and the second bearing. 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, wherein the second housing is not directly connected to the first housing, and the first housing and the second housing are connected to each other. At least one transducer configured to output an angle signal corresponding to the rotation angle of the shaft with respect to the first housing around the rotation axis, An inner spacer coupled to the inner race of the first bearing and the inner race of the second bearing, and an outer spacer coupled to the outer race of the first bearing and the outer race of the second bearing, wherein the majority of the outer surface of the outer spacer is exposed to form part of the housing of the CMM, and the inner spacer and outer spacer CMM, including. (Item 16) The CMM according to item 15, wherein each of the first and second housings extends axially along a longitudinal axis parallel to the rotation axis. (Item 17) The axial lengths of the first housing and the second housing are such that the first housing and the second housing do not cover most of the outer surface of the outer spacer, as described in item 16. (Item 18) The CMM according to item 17, wherein the first housing and the second housing are each adhesively bonded to the outer surface of the outer spacer. (Item 19) The inner spacer is bonded to the shaft adhesively, as described in item 15. (Item 20) The CMM according to item 15, wherein the majority of the outer surface of the outer tubular spacer is exposed to represent the outermost layer of at least one of the swivel joints. Brief Description of the Drawings

[0008] [Figure 1A] Figure 1A-1C shows a perspective view of an exemplary coordinate measuring machine (CMM). [Figure 1B] Figure 1A-1C shows a perspective view of an exemplary coordinate measuring machine (CMM). [Figure 1C] Figure 1A-1C shows a perspective view of an exemplary coordinate measuring machine (CMM). [Figure 1D] Figure 1D shows a cross-sectional view of the exemplary CMM shown in Figures 1A-1C.

[0009] [Figure 2A] Figures 2A and 2B illustrate a cross-sectional view and a partially exploded view of the exemplary swivel joint of the CMM shown in Figure 1A-1D, respectively. [Figure 2B] Figures 2A and 2B illustrate a cross-sectional view and a partially exploded view of the exemplary swivel joint of the CMM shown in Figure 1A-1D, respectively.

[0010] [Figure 3A] Figures 3A and 3B illustrate the cross-sectional view and partially exploded view of the hinge joint of the CMM shown in Figure 1A-1D, respectively. [Figure 3B] Figures 3A and 3B illustrate the cross-sectional view and partially exploded view of the hinge joint of the CMM shown in Figure 1A-1D, respectively.

[0011] [Figure 4A] Figures 4A and 4B illustrate the cross-sectional and partially exploded views, respectively, of the exemplary base and swivel joint of the CMM shown in Figures 1A-1D. [Figure 4B] Figures 4A and 4B illustrate the cross-sectional and partially exploded views, respectively, of the exemplary base and swivel joint of the CMM shown in Figures 1A-1D.

[0012] [Figure 5A] Figures 5A-5C illustrate cross-sectional and partially exploded views of the exemplary measurement probe of the CMM shown in Figure 1A-1D. [Figure 5B]Figures 5A-5C illustrate cross-sectional and partially exploded views of the exemplary measurement probe of the CMM shown in Figure 1A-1D. [Figure 5C] Figures 5A-5C illustrate cross-sectional and partially exploded views of the exemplary measurement probe of the CMM shown in Figure 1A-1D. [Modes for carrying out the invention]

[0013] (Detailed explanation) Figures 1A-1C illustrate a perspective view of an exemplary coordinate measuring machine (CMM) 1. Figure 1D illustrates a cross-sectional view of the exemplary CMM 1. The CMM 1 includes an articulated arm 2, a base 4, and a measuring probe 6. The articulated arm 2 is attached to the base 4 at one end and to the measuring probe 6 at the other end. The base 4 may be attached, for example, to a base plate 5, and the arm 2 may be attached, for example, to 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 arm sections 8, 9 may vary depending on their intended use. In one embodiment, the articulated arm may have an overall length of approximately 48 inches. This arm dimension provides a portable CMM that is very suitable for measurements currently performed using typical hand tools such as micrometers, height gauges, calipers, and equivalents. The articulated arm 2 may have smaller or larger dimensions.

[0015] The rotary joint generally includes two types of joints: swivel joints 12, 16, and 20, and hinge joints 14, 18, and 22. The swivel joints 12, 16, and 20 are positioned along the arm 2 in a substantially axial or longitudinal direction. The hinge joints 14, 18, and 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 paired as shown in Figures 1A-1D, although the joints may be arranged in other configurations. Due to the multiple rotary joints, the arm 2 is manually positionable, meaning that the user can freely manually move the probe 6 to any position within a radius that is substantially anchored to the base 4 of the CMM 1. Each of these joints is generally shown in Figures 2A-5C.

[0016] Generally, the base plate 5 of the base 4 is attached to the CMM 1 on the work surface, 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] Figure 2A shows a partial cross-sectional view of swivel joint 16, while Figure 2B shows an exploded view of an exemplary swivel joint 16. Each figure shows only the end portion of swivel joint 16, with the unshown central portion of the swivel joint corresponding to arm section 8. Swivel joint 16 will be used here to describe swivel joints 12, 16, and 20 in general, even though the swivel joints may not be identical. 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 made from a rigid but relatively lightweight material such as carbon fiber or aluminum, as well as from steel. In one embodiment, the shaft 30 may be made from steel or ceramic to match the material from which the bearings 32, 34 are made. Similar to the relatively long shaft 30, the spacers 301a, 301b may be tubes made from the same rigid but relatively lightweight material as the shaft 30, including carbon fiber, ceramic, or steel.

[0019] At one end of the swivel joint 16, the housing 48 has a port in which the end of the shaft 30 resides permanently, and a yoke 48a that operably connects the swivel joint 16 to the aforementioned hinge joint (see Figure 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 the end of the shaft 30 resides permanently.

[0020] As can be seen in most detail in Figure 2A, at one end of the swivel joint 16, the inner diameter of the port of the housing 48 engages with the outer diameter or outer race of the bearing 32 (for example, it is fixedly mounted to it). The port of the housing 48 may be glued to the outer diameter or outer race of the bearing 32, for example. The shaft 30 has an outer diameter over a portion of it that engages with the inner diameter or inner race of the bearing 32 (for example, it is fixedly mounted to it). The shaft 30 may be glued to the inner diameter or inner race of the bearing 32, for example. At the other end of the swivel joint 16, the inner diameter of the port of the housing 49 engages with the outer diameter or outer race of the bearing 34 (for example, it is fixedly mounted to it). The port of the housing 49 may be glued to the outer diameter or outer race of the bearing 34, for example. The shaft 30 has an outer diameter over a portion of it that engages with the inner diameter or inner race of the bearing 34 (for example, it is fixedly mounted to it). The shaft 30 may be glued, for example, to the inner diameter or inner race of the bearing 34. The shaft 30 therefore rotates about the axis a of rotation 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 on it, configured to output an angle signal corresponding to the rotation angle of the shaft 30 relative to the housings 48, 49 around the rotation axis 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 may be operably mounted (e.g., using a suitable adhesive) to the end of the shaft 30 spaced apart from and aligned with the read head on the PCB 36, which is operably mounted to the housing 48 (e.g., using fasteners and / or a suitable adhesive). The positions of the disk 38 and the read head may be reversed so that the disk 38 is operably mounted to the housing 48 and the read head rotates with the shaft 30 so that it is rotatable relative to the other while maintaining optical communication. The encoder is commercially available from Celera Motion, for example, under the trademark name MicroE Encoder. Each PCB36 may also include a processor for receiving angle signals from the read head, and a transceiver and connector for connecting the PCB36 to the CMM1's communication bus and / or other wiring. Each PCB36 may also include a temperature sensor connected to the processor to provide thermal compensation for room temperature fluctuations.

[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 from dust contamination.

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

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

[0025] The swivel joint 16 of arm section 8 is a relatively long joint, as can be understood from Figures 1A-1D. In one embodiment, the shaft 30 is at least 6 inches long. Such long joints have conventionally presented problems because improved precision required concentricity between the bearing bores within housings 48 and 49, as described in detail in U.S. Patent No. 10,267,614 (which is incorporated herein by reference as a whole). The prior art (e.g., U.S. Patent No. 10,267,614, see Figure 3C) used special fasteners to align those bores for improved concentricity. This process was redundant and left room for further concentricity improvement. The prior art (e.g., U.S. Patent No. 10,267,614, see Figure 3E) also applied bearing preload using its own weight or a spring washer, which also left room for further improvement. The swivel joint 16 uses a novel and unique arrangement to address these problems.

[0026] The swivel joint 16 may include spacers 301a, 301b, which, for the unique configuration of the swivel joint 16, can serve a dual role as spacers (involved in maintaining appropriate distance and preload between bearings 32, 34) and as the housing or outermost layer of the CMM 1. This unique design solves the concentricity problem in the prior art, as it provides a rigid, concentric swivel joint bearing assembly that incorporates bearings 32, 34 and spacers 301. The unique design with spacers 301 also provides an improvement in bearing preload.

[0027] In the illustrated embodiment, the inner spacer 301a is a tubular spacer positioned 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 positioned 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 and precisely lapped to maximize the precision of the structure formed by the spacers 301a, 301b and the bearings 32, 34. Also, as shown in Figure 2A, most of the outer surface of the outer spacer 301b is exposed (i.e., there is no additional cladding across the spacer 301b), and therefore the outer surface of the outer spacer 301b is the outermost layer of the swivel joint 16. This means that the outer surface of the outer spacer 301b forms part of the housing of the CMM 1.

[0028] Since the outer surface of the outer spacer 301b is part of the housing of the CMM1, no additional fasteners are required. In addition, spacers 301a and 301b add rigidity to the swivel joint bearing assembly of the CMM1 compared to conventional CMMs, which reduces bending / flexing and therefore increases rigidity, and ultimately accuracy. Partly due to this unique design, the CMM1 achieves significantly better accuracy than prior art portable coordinate measuring machines.

[0029] Figure 3A illustrates a cross-sectional view of hinge joint 18, while Figure 3B illustrates an exploded view of an exemplary hinge joint 18. Hinge joint 18 will be used here to describe hinge joints 14, 18, and 22 in general, even if the hinge joints are not identical. At least some of the components of hinge joint 18 are substantially similar to the components discussed above in detail with reference to swivel joints 12 and 16, and therefore these similar components are identified in Figures 3A and 3B using the same reference designators as in the preceding 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 in most detail in Figure 3A, the housing 78 has ports that engage with (for example, are fixedly mounted to) the outer diameter or outer races of the bearings 32, 34. The ports of the housing 78 may, for example, be glued to the outer diameter or outer races of the bearings 32 and 34. The shaft 80 has an outer diameter over part of it that engages with (for example, is fixedly mounted to) the inner diameter or inner races of the bearings 32, 34. The shaft 80 may, for example, be glued to the inner diameter or inner races of the bearings 32, 34. The shaft 80 therefore rotates about the axis b of rotation of the bearings 32, 34 and the housing 78 of the hinge joint 18.

[0031] Spacers 301a and 301b may be tubes, fabricated from materials having the same rigidity as the shaft 80 but being relatively lighter, including carbon fiber, ceramic, or steel. Spacers 301a and 301b may be installed between bearings 32 and 34 to maintain an appropriate spacing between them and, more importantly, to set and preserve preload. In the illustrated embodiment, the inner spacer 301a is a tubular spacer positioned 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 positioned in contact with the outer race of the first bearing 32 and the outer race of the second bearing 34. Spacers 301a and 301b are fitted and precisely lapped to maximize the precision of the structure formed by the spacers 301a and 301b and the bearings 32 and 34.

[0032] The shaft 80 is configured to engage with the yoke of an adjacent swivel joint, such as the yoke 48a of the swivel joint 20. In the illustrated embodiment, the shaft 80 has a groove 72 machined or otherwise formed thereon to create a gap (e.g., 5 mil or 127 μm) for better bonding of the adhesive with the yoke of an adjacent swivel joint, such as the yoke 48a of the swivel joint 16. The housing 78 has a housing bracket 78a built, welded, or otherwise disposed thereon, on which a housing bracket 78a is constructed, welded, or otherwise disposed thereon, creating a gap 79 for one of the yoke projections to engage with the shaft 80, such that the two projections of the yoke straddle the bearings 32, 34 between them.

[0033] The encoder cavity dust seal washer 302 is held in place by a washer 303 which is glued to the inside of the bracket 78a and to 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 (inside the bracket 78a) from dust contaminants from each end.

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

[0035] Located near the end of the shaft 80, rather than inside the housing 78 between bearings 32 and 34, the PCB 36 and encoder disk 38 may be exposed to external loads, such as a user resting their hands against the joint 18, specifically the plastic cover 82. This can lead to angular measurement errors. To protect against such external loads, the joint 18 may also include a bracket 305, which may be machined from aluminum, steel, or the like and mounted on the housing 78. As shown in Figure 3B, the housing 78 may have threaded holes 78b formed thereon to match holes in the protective bracket 305, so that the bracket 305 can be mounted on the housing 78 using screws. As seen in Figure 3A, the bracket 305 protects the PCB 36 and encoder disk 38 from external loads. The joint 18 may further include a cover 82, which is operably mounted on the housing 78, covers the wiring harness, and seals the PCB 36 and encoder disk 38 from dust. The cover 82 may have threaded holes formed thereon to match threaded holes in the bracket 305, so that the cover 82 can be attached to the bracket 305 using screws.

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

[0037] Figures 4A and 4B illustrate a cross-sectional and exploded view of an exemplary joint 12 and base plate 204. The base plate 204 may have holes 208 formed thereon for receiving fasteners for mounting the CMM1 to a mounting surface or magnet plate. The main PCB 158 may be located inside the base plate 204. The base plate 204 may have a cover plate 210 that attaches the base plate 204 to the cavity in which the PCB 158 resides, for covering the opening. 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 to the base plate 204 using screws. An insulator 306 (e.g., Kapton film) may be placed 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 central hole of the encoder PCB 36 to seal the encoder cavity from dust contamination. As can be seen in most detail in Figure 4A, the housing 28 has ports that engage with (e.g., are fixedly mounted to) the outer diameter or outer race of the bearings 32, 34. The ports of the housing 28 may be glued to, for example, the outer diameter or outer race of the bearings 32 and 34. The shaft 30 has an outer diameter over part of it that engages with (e.g., is fixedly mounted to) the inner diameter or inner race of the bearings 32, 34. The shaft 30 may be glued, for example, to the inner diameter or inner race of the bearings 32, 34. The shaft 30 thus rotates about the axis of rotation 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 positioned 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 positioned 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 fitted and precision lapped to maximize the precision of the structure formed by the spacers 301a, 301b and the bearings 32, 34. The spacers 301a and 301b may be tubes fabricated from materials that are as rigid as the shaft 30 but relatively lighter, including carbon fiber, ceramic, or steel. The spacers 301a and 301b may be positioned between the bearings 32, 34 to maintain an appropriate spacing between them and, more importantly, to set and preserve preload.

[0040] Similar to the swivel joint discussed above, the PCB 36 of the swivel joint 12 has at least one transducer disposed thereon, configured to output an angle signal corresponding to the rotation angle of the shaft 30 relative to the housing 28 about the rotation axis c. The encoder PCB 36 and encoder disk 38 may be housed in a cavity in the base plate 204, parallel to the main PCB 158. This arrangement is particularly space-efficient and compact. Taller components on the main PCB 158 may be placed near the higher edges of the main PCB 158 (not overlapping perpendicularly with the encoder PCB 36).

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

[0042] The measuring 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 confirmation switch 132. The operator may use these switches to perform a measurement during operation (take switch 131) and to confirm the measurement (confirmation switch 132). The handle 128 is generally shaped to resemble a human gripping motion, which is more ergonomic than at least some prior art probes. The handle 128 may also house a switch PCB 134 on which switches 131 and 132 may be mounted. The switch PCB 134 is electrically coupled to a host component PCB 125 for processing signals from switches 131 and 132. In one embodiment, PCB125 includes a wireless (e.g., Wi-Fi, Bluetooth®, etc.) transmitter (instead of an electrical connection to the CMM1's communication bus) that wirelessly transmits take and acknowledgment signals associated with switches 131 and 132 to a host PC that controls the CMM1, for example. Wireless transmission of take and acknowledgment signals associated with switches 131 and 132 significantly simplifies the organization and wiring of the probe 6. The probe 6 may also include a battery 309 for powering the electronics within it.

[0043] The handle 128 incorporates two plastic bearings 310 that are mounted on an aluminum block 311 and rotate around the housing 126. A tactile 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 used herein. These definitions include various embodiments or forms of components that fall within the scope of the terms and may be used for implementation. Embodiments are not intended to be limiting. Both singular and plural forms of terms may exist within these definitions.

[0045] As used herein, an “operable connection” or “operable coupling,” that is, a connection by which entities are “operably connected” or “operably coupled,” is a connection in which entities are connected in such a manner that they can perform as intended. An operable connection may be a direct connection, or an indirect connection that exists between entities that are operationally connected, where an intermediate entity or multiple entities cooperate or are otherwise part of the connection. In the context of signaling, an “operable connection,” that is, a connection by which entities are “operably connected,” is a connection on which signals, physical communications, or logical communications can be transmitted or received. Typically, an operable connection includes a physical interface, an electrical interface, or a data interface, but it should be noted that an operable connection may include different combinations of these or other types of connections, as long as they are sufficient to enable operational control. For example, two entities can be operationally connected by enabling them to communicate signals with each other directly or through one or more intermediate entities such as a processor, operating system, logic, software, or other entities. A logical or physical communication channel can be used to create an operational 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] Wherever the terms “includes” or “including” are used in the detailed description or claims, they are intended to be inclusive in a similar manner to the term “comprising” when used as a transitional term in a claim. Furthermore, wherever the term “or” is used in the detailed description or claims (e.g., “A or B”), it 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 used. Thus, the use of the term “or” in this specification is inclusive and non-exclusive. See Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d. Ed. 1995). Exemplary systems, methods, etc., are illustrated by describing embodiments, and these embodiments are described in considerable detail; however, it is not the applicant's intention to limit or restrict the scope in any way to such detail. Naturally, it is not possible to describe all conceivable combinations of components or methodologies for the purpose of illustrating the systems, methods, etc., described herein. Additional advantages and modifications will be readily conceivable to those skilled in the art. Therefore, the present invention is not limited to the specific details, representative apparatus, and illustrative embodiments shown and described. Accordingly, this application is intended to encompass modifications, alterations, and variations that fall within the scope of the appended claims. Furthermore, the foregoing description is not intended to limit the scope of the present invention. Rather, the scope of the present 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 that engages with 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 the respective projection of 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 with the outer race of the first bearing and the outer race of the second bearing, An outer tubular spacer is positioned to contact the outer race of the first bearing and the outer race of the second bearing, and an inner tubular spacer is positioned to contact 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 mounted on the housing to which the PCB assembly is attached. The CMM according to claim 3, comprising:

5. At least one of the plurality of rotary joints is A plastic cover, wherein the plastic cover is mounted across the L-shaped mounting bracket so as to cover the L-shaped mounting bracket and the PCB assembly. The CMM according to claim 4, comprising:

6. 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 that engages with 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 of which is 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 of 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 with the outer race of the first bearing and 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.

7. The CMM according to claim 6, 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.

8. 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 6, comprising:

9. 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 6, comprising:

10. At least one of the plurality of rotary joints is An L-shaped mounting bracket, wherein the L-shaped mounting bracket is mounted on the housing to which the PCB assembly is attached. The CMM according to claim 9, comprising:

11. At least one of the plurality of rotary joints is A plastic cover, wherein the plastic cover is mounted across the L-shaped mounting bracket so as to cover the L-shaped mounting bracket and the PCB assembly. The CMM according to claim 10, comprising:

12. 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 that engages with 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 the respective projection of 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.

13. The CMM according to claim 12, 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.

14. 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 12, comprising:

15. 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 12, comprising:

16. At least one of the plurality of rotary joints is An L-shaped mounting bracket, wherein the L-shaped mounting bracket is mounted on the housing to which the PCB assembly is attached. The CMM according to claim 15, comprising:

17. At least one of the plurality of rotary joints is A plastic cover, wherein the plastic cover is mounted across the L-shaped mounting bracket so as to cover the L-shaped mounting bracket and the PCB assembly. The CMM according to claim 16, comprising:

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