# Patent

## Title
Low profile load transducer

## Abstract

A load transducer includes a central body portion; a plurality of beams extending outwardly from the central body portion, each of the plurality of beams including an end portion that is supported in a cantilevered manner from the central body portion; and a plurality of load cells, each of the load cells being disposed on one of the beams, the plurality of load cells configured to measure a plurality of force and/or moment components. In addition to being very accurate and reliable, the load transducer has a low profile and small size. This invention is easily manufactured using strain gage technology.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This patent application claims priority to, and incorporates by reference in its entirety, U.S. Provisional Patent Application No. 61/887,357, entitled “Low Profile Load Transducer”, filed on Oct. 5, 2013.


STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
Not Applicable.
INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISK
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of the invention relates to multi-component load transducers utilizing multiple strain gage load channels for precise measurement of forces and moments and, more particularly, to beam-style load cells requiring an overall small size, high capacity, and yet high sensitivity.
2. Background and Related Art
The use of strain gages in load transducers to measure forces and moments is a known art. A transducer can incorporate one or more load channels. Each load channel measures one of the load components, and is comprised of one or more strain gages mounted to one or more elastic elements that deform under the applied load. An appropriate circuitry relates the resistance change in each set of gages to the applied force or moment. Strain gages have many industrial, medical, and electrical applications due to their small size, low production cost, flexibility in installation and use, and high precision.
A typical low profile, small, multi-component load transducer only functions correctly when the axial (i.e. vertical) force acts relatively central to the transducer. Specifications of such transducers indicate a maximum allowable offset for the force being approximately half the diameter of the transducer. Technical specifications of transducers are given as the allowable force and moment ratings, where the moment rating is obtained by multiplying the maximum allowable force with the maximum allowable offset of the force.
Transducers can be used to measure forces and moments in linkages such as those found in a robotic arm, where the links are connected by joints, and the magnitude and offset of the forces transmitted by these joints are used to control the linkage. In such applications, it is desirable to have a transducer which has significantly higher moment capacity than those available in the market. Accordingly, there is a need for an improved multi-component, low profile load transducer with high moment capacity.
BRIEF SUMMARY OF EMBODIMENTS OF THE INVENTION
Accordingly, the present invention is directed to a low profile load transducer that substantially obviates one or more problems resulting from the limitations and deficiencies of the related art.
In accordance with one or more embodiments of the present invention, there is provided a load transducer that includes: a central body portion having a plurality of sides; a plurality of beams extending outwardly from the sides of the central body portion, each of the plurality of beams being supported in a cantilevered manner from the central body portion; and a plurality of load cells, each of the load cells being disposed on one of the beams, the plurality of load cells configured to measure a plurality of force and/or moment components.
In a further embodiment of the present invention, one or more of the plurality of load cells comprises a strain gage configured to measure a load component applied at a respective one of the end portions of the beams.
In yet a further embodiment, the central body portion and the plurality of beams are each part of a transducer frame, the transducer frame being compact and of one-piece construction.
In still a further embodiment, the plurality of beams comprises at least six beams, and wherein the plurality of load cells comprises at least three load cells that are configured to be sensitive to a vertical force component, at least two load cells that are configured to be sensitive to a first shear force component, and at least two load cells that are configured to be sensitive to a second shear force component, the first shear force component being generally perpendicular to the second shear force component, and each of the first and second shear force components being generally perpendicular to the vertical force component.
In yet a further embodiment, the plurality of beams comprises at least two pairs of beams that are disposed generally parallel to one another.
In still a further embodiment, each of the at least two pairs of beams comprises two beams that are laterally spaced apart from one another by a gap.
In yet a further embodiment, the plurality of beams comprises at least two generally U-shaped beams that are disposed diagonally opposite to one another across the central body portion.
In still a further embodiment, the plurality of beams comprises a first set of beams disposed on a first side of the central body portion and a second set of beams disposed on a second side of the central body portion, the first side of the central body portion being opposite to the second side of the central body portion, each of the first and second sets of beams comprising an arrangement of beams disposed in a generally C-shaped configuration.
In yet a further embodiment, the plurality of beams comprises a first set of beams disposed on a first side of the central body portion and a second set of beams disposed on a second side of the central body portion, the first side of the central body portion being opposite to the second side of the central body portion, each of the first and second sets of beams comprising an arrangement of beams disposed in a generally T-shaped configuration.
In still a further embodiment, the plurality of beams comprises at least two generally L-shaped beams that are disposed diagonally opposite to one another across the central body portion.
In yet a further embodiment, one or more of the plurality of load cells is configured as a bending beam load cell.
In still a further embodiment, one or more of the plurality of load cells is configured as a shear-web load cell.
In yet a further embodiment, electronics for the plurality of load cells are mounted on the central body portion.
In still a further embodiment, the plurality of beams are attached to the central body portion by one or more of the following: (i) an adhesive, (ii) welding, and (iii) one or more fasteners.
In accordance with one or more other embodiments of the present invention, there is provided a load transducer that includes: a central body portion having a plurality of sides; a plurality of beams extending outwardly from the sides of the central body portion, each of the plurality of beams including an end portion that is supported in a cantilevered manner from the central body portion; and a plurality of load cells, each of the load cells being disposed on one of the beams, the plurality of load cells including at least three load cells that are configured to be sensitive to a vertical force component, at least two load cells that are configured to be sensitive to a first shear force component, and at least two load cells that are configured to be sensitive to a second shear force component, the first shear force component being generally perpendicular to the second shear force component, and each of the first and second shear force components being generally perpendicular to the vertical force component.
In a further embodiment of the present invention, one or more of the plurality of load cells comprises a strain gage configured to measure a load component applied at a respective one of the end portions of the beams.
In yet a further embodiment, the central body portion and the plurality of beams are each part of a transducer frame, the transducer frame being compact and of one-piece construction.
In still a further embodiment, the plurality of sides of the central body portion comprise a first side, a second side disposed generally opposite to the first side, a third side, and a fourth side disposed generally opposite to the third side; and at least a first of the plurality of beams extends outwardly from the first side of the central body portion, at least a second of the plurality of beams extends outwardly from the second side of the central body portion, at least a third of the plurality of beams extends outwardly from the third side of the central body portion, and at least a fourth of the plurality of beams extends outwardly from the fourth side of the central body portion.
In yet a further embodiment, one or more of the plurality of beams comprises a first top surface that is disposed at a first elevation relative to a bottom surface of the central body portion and a second top surface that is disposed at a second elevation relative to a bottom surface of the central body portion, the second elevation being greater than the first elevation; and wherein a recessed area created by the difference in elevation between the second elevation and the first elevation is used to accommodate one or more electrical components of the plurality of load cells.
In still a further embodiment, one or more of the plurality of beams comprises a mounting aperture disposed near a respective end thereof for accommodating a fastener.
In yet a further embodiment, one or more of the plurality of load cells is configured as a bending beam load cell.
In still a further embodiment, one or more of the plurality of load cells is configured as a shear-web load cell.
In yet a further embodiment, the plurality of beams are attached to the central body portion by one or more of the following: (i) an adhesive, (ii) welding, and (iii) one or more fasteners.
In accordance with yet one or more other embodiments of the present invention, there is provided a load transducer that includes: a plurality of beams arranged in a band-shaped configuration, at least one of the plurality of beams being disposed generally perpendicular to at least another one of the plurality of beams; and a plurality of load cells, each of the load cells being disposed on one of the beams, the plurality of load cells configured to measure a plurality of force and/or moment components.
In a further embodiment of the present invention, the load transducer further includes a central body portion that is at least partially circumscribed by the plurality of beams arranged in the band-shaped configuration.
In yet a further embodiment, at least one of the plurality of beams arranged in the band-shaped configuration is spaced apart from a lateral side of the central body portion by a gap.
In still a further embodiment, at least one of the plurality of beams comprises a standoff portion for spacing one or more of the plurality of load cells apart from a structure to which the load transducer is mounted.
In accordance with yet one or more other embodiments of the present invention, there is provided a load transducer that includes: a central body portion; a plurality of beams extending outwardly from the central body portion, each of the plurality of beams including an end portion that is supported in a cantilevered manner from the central body portion; and a plurality of load cells, each of the load cells being disposed on one of the beams, the plurality of load cells configured to measure three force components and three moment components.
In a further embodiment of the present invention, the plurality of beams comprises at least six beams.
In yet a further embodiment, the three force components comprise a vertical force component, a first shear force component, and a second shear force component, the first shear force component being generally perpendicular to the second shear force component, and each of the first and second shear force components being generally perpendicular to the vertical force component; and the plurality of load cells comprises at least three load cells that are configured to be sensitive to the vertical force component, at least two load cells that are configured to be sensitive to the first shear force component, and at least two load cells that are configured to be sensitive to the second shear force component.
In still a further embodiment, the plurality of beams are attached to the central body portion by one or more of the following: (i) an adhesive, (ii) welding, and (iii) one or more fasteners.
From the foregoing disclosure and the following more detailed description of various preferred embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology and art of load transducers. Particularly significant in this regard is the potential the invention affords for providing a low profile load transducer with high moment capacity. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below.



BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a perspective view of a low profile load transducer, according to a first embodiment of the invention;
FIG. 2 is a first side view of the low profile load transducer of FIG. 1, according to the first embodiment of the invention;
FIG. 3 is a second side view of the low profile load transducer of FIG. 1, according to the first embodiment of the invention;
FIG. 4 is a top view of the low profile load transducer of FIG. 1, according to the first embodiment of the invention;
FIG. 5 is a block diagram illustrating data manipulation operations carried out by the load transducer data processing system, according to an embodiment of the invention;
FIG. 6 is a perspective view of a low profile load transducer, according to a second embodiment of the invention;
FIG. 7 is a first side view of the low profile load transducer of FIG. 6, according to the second embodiment of the invention;
FIG. 8 is a second side view of the low profile load transducer of FIG. 6, according to the second embodiment of the invention;
FIG. 9 is a top view of the low profile load transducer of FIG. 6, according to the second embodiment of the invention;
FIG. 10 is a perspective view of a low profile load transducer, according to a third embodiment of the invention;
FIG. 11 is a first side view of the low profile load transducer of FIG. 10, according to the third embodiment of the invention;
FIG. 12 is a second side view of the low profile load transducer of FIG. 10, according to the third embodiment of the invention;
FIG. 13 is a top view of the low profile load transducer of FIG. 10, according to the third embodiment of the invention;
FIG. 14 is a bottom view of the low profile load transducer of FIG. 10, according to the third embodiment of the invention;
FIG. 15 is a perspective view of a low profile load transducer, according to a fourth embodiment of the invention;
FIG. 16 is a first side view of the low profile load transducer of FIG. 15, according to the fourth embodiment of the invention;
FIG. 17 is a second side view of the low profile load transducer of FIG. 15, according to the fourth embodiment of the invention;
FIG. 18 is a top view of the low profile load transducer of FIG. 15, according to the fourth embodiment of the invention;
FIG. 19 is a perspective view of a low profile load transducer, according to a fifth embodiment of the invention;
FIG. 20 is a perspective view of a low profile load transducer, according to a sixth embodiment of the invention;
FIG. 21 is a perspective view of a low profile load transducer, according to a seventh embodiment of the invention;
FIG. 22 is a perspective view of a low profile load transducer, according to an eighth embodiment of the invention;
FIG. 23 is a perspective view of a low profile load transducer, according to a ninth embodiment of the invention;
FIG. 24 is a perspective view of a low profile load transducer, according to a tenth embodiment of the invention; and
FIG. 25 is a perspective view of an exemplary mounting arrangement for the low profile load transducer illustrated in FIGS. 15-18.



It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the load transducers as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes of the various components, will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments have been enlarged or distorted relative to others to facilitate visualization and clear understanding. In particular, thin features may be thickened, for example, for clarity or illustration. All references to direction and position, unless otherwise indicated, refer to the orientation of the load transducers illustrated in the drawings. In general, up or upward generally refers to an upward direction within the plane of the paper in FIG. 1 and down or downward generally refers to a downward direction within the plane of the paper in FIG. 1.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
It will be apparent to those skilled in the art, that is, to those who have knowledge or experience in this area of technology, that many uses and design variations are possible for the improved load transducers disclosed herein. The following detailed discussion of various alternative and preferred embodiments will illustrate the general principles of the invention. Other embodiments suitable for other applications will be apparent to those skilled in the art given the benefit of this disclosure.
Referring now to the drawings, FIGS. 1-4 illustrate a load transducer 10 according to a first exemplary embodiment of the present invention. This load transducer 10 is designed to have a low profile, small size, trivial weight, high sensitivity, and easy manufacturability. The load transducer 10 generally includes a one-piece compact transducer frame 12 having a central body portion 14 and a plurality of beams 16, 18, 20, 22, 24, 26, 28, 30 extending outwardly from the central body portion 14. As best illustrated in the perspective view of FIG. 1, each of the beams 16, 18, 20, 22, 24, 26, 28, 30 comprises a respective load cell or transducer element for measuring forces and/or moments. For example, the load cells of beams 16, 18, 24, 26 are configured to respectively measure the forces F1, F2, F3, F4 with force vector components F1x, F1y, F1z, F2x, F2y, F2z, F3x, F3y, F3z, F4x, F4y, F4z. In addition to forces, the output of the load cells can also be used to determine moments and the point of application of a force (i.e., its center of pressure). Referring again to FIG. 1, it can be seen that the illustrated load transducer 10 comprises eight single or multi-axis load cells that are mounted to a common structure or body portion 14.
The illustrated transducer frame 12 is shown in FIGS. 1-4. The illustrated transducer frame 12 includes the central body portion 14 and a plurality of beams 16, 18, 20, 22, 24, 26, 28, extending outwardly therefrom. In the illustrated embodiment, the transducer frame 12 is milled as one solid and continuous piece of a single material. That is, the transducer frame 12 is of unitary or one-piece construction with the body portion 14 and the beams 16, 18, 20, 22, 24, 26, 28, 30 integrally formed together. The transducer frame 12 is preferably machined in one piece from aluminum, titanium, steel, or any other suitable material that meets strength and weight requirements. Alternatively, the beams 16, 18, 20, 22, 24, 26, 28, 30 can be formed separately and attached to the body portion 14 in any suitable manner.
With reference to FIG. 1, it can be seen that the illustrated central body portion 14 is generally in the form of rectangular prism (i.e., a square prism) with substantially planar top, bottom, and side surfaces. In FIG. 1, it can be seen that the body portion 14 comprises a first pair of opposed sides 14a, 14c and a second pair of opposed sides 14b, 14d. The side 14a is disposed generally parallel to the side 14c, while the side 14b is disposed generally parallel to the side 14d. Each of the sides 14a, 14b, 14c, 14d is disposed generally perpendicular to the planar top and bottom surfaces. Also, each of the first pair of opposed sides 14a, 14c is disposed generally perpendicular to each of the second pair of opposed sides 14b, 14d. While not explicitly shown in FIGS. 1-4, the central body portion 14 may comprise one or more apertures disposed therethrough for accommodating fasteners (e.g., screws) that attach electronics or circuitry to the body portion 14. In addition to fasteners, it is noted that any other suitable means for attachment of the electronics or circuitry can alternatively be utilized (e.g., suitable adhesives, etc.). While the illustrated body portion 14 is generally in the form of a square prism, it is to be understood that the body portion 14 can alternatively have other suitable shapes.
As shown in FIGS. 1-4, the illustrated beams 16, 18, 20, 22, 24, 26, 28, 30 are each attached to one of the sides 14a, 14b, 14c, 14d of the body portion 14, and extend generally horizontally outward therefrom. In particular, beams 16, 18 extend generally horizontally outward from side 14a of the body portion 14, beams 20, 22 extend generally horizontally outward from side 14b of the body portion 14, beams 24, 26 extend generally horizontally outward from side 14c of the body portion 14, and beams 28, 30 extend generally horizontally outward from side 14d of the body portion 14. In addition, each of the illustrated beams 16, 18, 20, 22, 24, 26, 28, 30 extend substantially parallel to the top and bottom surfaces of the body portion 14. Each of the illustrated beams 16, 18, 20, 22, 24, 26, 28, 30 has a cantilevered end relative to the body portion 14 that allows for deflection of the ends of the beams 16, 18, 20, 22, 24, 26, 28, 30 in the vertical direction.
With particular reference to FIGS. 1 and 4, it can be seen that the beams 16, 18 extending from side 14a are substantially parallel to one another, and laterally spaced apart from one another by a gap. Opposed beams 24, 26, which extend from side 14c, also are substantially parallel to one another, and laterally spaced apart from one another by a gap. Beam 16 extends in a longitudinal direction that is generally co-linear with, but opposite to the extending direction of beam 26 (i.e., both beams 16 and 26 are aligned along central longitudinal axis LA1). Similarly, beam 18 extends in a longitudinal direction that is generally co-linear with, but opposite to the extending direction of beam 24 (i.e., both beams 18 and 24 are aligned along central longitudinal axis LA2). The beams 20, 22 extending from side 14b are substantially parallel to one another, and laterally spaced apart from one another by a gap. Opposed beams 28, 30, which extend from side 14d, also are substantially parallel to one another, and laterally spaced apart from one another by a gap. Beam 20 extends in a longitudinal direction that is generally co-linear with, but opposite to the extending direction of beam 30 (i.e., both beams 20 and 30 are aligned along central longitudinal axis LA3). Similarly, beam 22 extends in a longitudinal direction that is generally co-linear with, but opposite to the extending direction of beam 28 (i.e., both beams 22 and 28 are aligned along central longitudinal axis LA4). The illustrated beams 16, 18, 20, 22, 24, 26, 28, 30 are provided with generally vertically extending apertures 32 near their ends for accommodating fasteners that are used to secure the load transducer 10 to additional structures. Although, it is noted that any other suitable means for attachment of the load transducer 10 can alternatively be utilized (e.g., a suitable adhesive for attaching metallic components to one another).
The main body portions of illustrated beams 16, 18, 20, 22, 24, 26, 28, 30 have a rectangular-shaped cross section to form generally planar, opposed top and bottom surfaces, and generally planar, opposed side surfaces for attachment of load cell components as described hereinafter. The illustrated beams 16, 18, 20, 22, 24, 26, 28, 30 have generally cylindrical end portions, which include the fastener apertures 32. As best shown in FIG. 1, the illustrated top planar surfaces of the beam main body portions of beams 16, 18, 24, 26 are recessed below the top surfaces of the beam cylindrical end portions to protect the load cell components from engagement with the structure to which the load transducer 10 is attached, while the illustrated bottom planar surfaces of the beam main body portions of beams 20, 22, 28, 30 are recessed above the bottom surfaces of the beam cylindrical end portions to protect the load cell components from engagement with the structure to which the load transducer 10 is attached. In other words, as shown in FIG. 1, the cylindrical end portions of beams 16, 18, 24, 26 are provided with a top standoff portion (i.e., a cylindrical portion protruding from the top of each beam having the aperture 32), while the cylindrical end portions of beams 20, 22, 28, 30 are provided with a bottom standoff portion (i.e., a cylindrical portion protruding from the bottom of each beam having the aperture 32). While not explicitly shown in the figures, beams 16, 18, 20, 22, 24, 26, 28, 30 may also include apertures disposed therethrough for increasing the deflectability of the beams 16, 18, 20, 22, 24, 26, 28, 30 as desired (e.g., the apertures could be disposed below, or adjacent to each of the strain gages 34, 36, 38). In order to accommodate these apertures, the length of each beam 16, 18, 20, 22, 24, 26, 28, 30 could be extended so that multiple strain gages 34, 36 on a common beam could be spaced apart from one another along a length of the beam (i.e., each strain gage 34, 36 would occupy a dedicated, respective segment of the beam). It is noted that these apertures can be of any suitable size and shape as needed and also can be eliminated if desired. It is further noted that the beams 16, 18, 20, 22, 24, 26, 28, 30 can alternatively have other cross-sectional shapes depending on whether it is desired to have planar surfaces at the top and/or bottom or left and/or right sides for the load cell components but the illustrated rectangular shape is particularly desirable because the same frame can be used for multiple configurations of the transducer load cells.
The illustrated one-piece frame 12 has a low profile or is compact. The terms “low profile” and “compact” are used in this specification and the claims to mean that the height is substantially smaller than the footprint dimensions so that the load transducer 10 can be utilized in a mechanical joint without significant changes to the mechanical joint. The illustrated one piece frame 12 has a height H that is about 20% its footprint width W1 or W2 (see FIGS. 2, 3, 7, and 8). As a result, the load transducer 10 has a low profile or is compact and has a height H that is about 20% its footprint width W1 or W2. The term “load cell” is used in the specification and claims to mean a load sensing element of the load transducer that is capable of sensing one or more load components of the applied load.
As best shown in FIG. 1, the illustrated load cells are located on beams 16, 18, 20, 24, 26, and 30. In the illustrated embodiment, beams 22, 28 do not contain any load cells, but, in other embodiments, may contain load cells with strain gages 38 similar to beams 20, 30. Beams 16, 26 also may contain strain gages 36, similar to beams 18, 24, in other embodiments. In a preferred embodiment, each load cell comprises one or more strain gages 34, 36, 38. Specifically, in the illustrated embodiment, beams 16, 18, 24, 26 each comprise a strain gage 34 disposed on the top surface thereof that is sensitive to the vertical force component (i.e., a FZ strain gage). Opposed beams 18, 24 also each comprise a strain gage 36 disposed on a side surface thereof that is sensitive to a first shear force component (i.e., a FX strain gage). Opposed beams 20, 30 each comprise a strain gage 38 disposed on a side surface thereof that is sensitive to a second shear force component (i.e., a FY strain gage). All eight (8) of the strain gages 34, 36, 38 are measuring a difference in the bending moments in the beams. If the applied shears to each of the two parallel beams 18, 24 or 20, 30 are equal (which is most likely the case), this is an optimal number of strain gages for a six-component load transducer (i.e., for a load transducer that is capable of measuring the three (3) force components FX, FY, FZ and the three (3) moment components MX, MY, MZ). Shear web gages can also be used in lieu of one or more of the illustrated strain gages 34, 36, 38. Also, in other preferred embodiments alternate load and/or moment sensors may be utilized as required or desired as long as they do not interfere with the advantages of the design as a whole. For example, piezoelectric gages or Hall-effect sensors are possible alternatives to the strain gages 34, 36, 38.
As best shown in FIG. 1, the illustrated load cells are configured as bending beam load cells. The illustrated strain gages 34, 36, 38 are mounted to either top or side surfaces of the beams 16, 18, 20, 24, 26, 30 between their attachment locations to the body portion 14 and the cylindrical end portions thereof. Alternatively, the strain gages 34 can be mounted to the bottom surfaces of the beams 16, 18, 24, 26 between their attachment locations to the body portion 14 and the cylindrical end portions thereof, while the strain gages 36, 38 can be mounted to the opposite side surfaces of the beams 18, 20, 24, 30 between their attachment locations to the body portion 14 and the cylindrical end portions thereof. That is, the strain gages 34, 36, 38 are mounted to surfaces generally normal to the direction of applied vertical and/or shear forces (i.e., FX, FY, FZ). It is also noted that alternatively, the strain gages 34 can be mounted at both the top surface and the bottom surface of the beams 16, 18, 24, 26, and/or the strain gages 36, 38 can be mounted at both opposed side surfaces of the beams 18, 20, 24, 30. These strain gages 34, 36, 38 measure force either by bending moment or difference of bending moments at two cross sections. As force is applied to the ends of the beams (e.g., forces F1, F2, F3, F4 with force vector components F1x, F1y, F1z, F2x, F2y, F2z, F3x, F3y, F3z, F4x, F4y, F4z applied to the ends of respective beams 16, 18, 24, 26), the beams 16, 18, 20, 24, 26, 30 with strain gages attached thereto bend. This bending either stretches or compresses the strain gages 34, 36, 38, in turn changing the resistances of the electrical currents passing therethrough. The amount of change in the electrical voltage or current is proportional to the magnitude of the applied force (e.g., forces F1, F2, F3, F4 with force vector components F1x, F1y, F1z, F2x, F2y, F2z, F3x, F3y, F3z, F4x, F4y, F4z applied to the ends of respective beams 16, 18, 24, 26).
Alternatively, the load cells can be configured as shear-web load cells. In this configuration, the strain gages are mounted to either one of the lateral side surfaces of the beams between their attachment locations to the body portion 14 and the cylindrical end portions thereof. It is noted that alternatively, the strain gages can be mounted at both of the lateral side surfaces of the beams. Mounted in these positions, the strain gages directly measure shear as force is applied to the end of the beam.
As best shown in FIG. 1, the load transducer 10 measures applied forces (e.g., forces F1, F2, F3, F4 with force vector components F1x, F1y, F1z, F2x, F2y, F2z, F3x, F3y, F3z, F4x, F4y, F4z applied to the ends of respective beams 16, 18, 24, 26) at each of the load cells. The sum of the forces is the force being applied to any assembly attached to the top of the load transducer 10. The load cells of the beams 16, 26 measure the force being applied to one lateral side of the load transducer 10; whereas, load cells of the beams 18, 24 measure the force being applied to the other lateral side of the load transducer 10. The various moments are determined by subtracting the sum total of the forces acting on one pair of load cells from the sum total acting upon the opposite pair. For example, subtracting the sum total of the forces acting on load cell of beam 16 and load cell of beam 18 from the sum total of the forces acting on load cell of beam 24 and load cell of beam 26, subtracting the sum total of load cells of beams 18, 24 from the sum total of load cells of beams 16, 26.
The sensory information from the strain gages 34, 36, 38 is transmitted to a microprocessor which could then be used to control the assembly to which the load transducer is a part of such as a robotic assembly. As best shown in FIG. 1, the planar central body portion 14 of the transducer frame 12 provides an area where associated electronics and/or circuitry can be mounted. Alternatively, the electronics and/or circuitry can be mounted at any other suitable location. FIG. 5 schematically illustrates exemplary electronic components that can be included in the load transducer data processing system. The strain gages 34, 36, 38 of load transducer 10 may be electrically connected to a signal amplifier/converter 40, which in turn, is electrically connected to a computer 42 (i.e., a data acquisition and processing device or a data processing device with a microprocessor). The components 10, 40, 42 of the system may be connected either by wiring, or wirelessly to one another.
FIG. 5 graphically illustrates the acquisition and processing of the load data carried out by the exemplary load transducer data processing system. Initially, as shown in FIG. 5, external forces F1-F4 and/or moments are applied to the load transducer 10. When the electrical resistance of each strain gage 34, 36, 38 is altered by the application of the applied forces and/or moments, the change in the electrical resistance of the strain gages brings about a consequential change in the output voltage of the strain gage bridge circuit (e.g., a Wheatstone bridge circuit). Thus, in one embodiment, the eight (8) strain gages 34, 36, 38 output a total of eight (8) analog output voltages (signals). In some embodiments, the eight (8) analog output voltages from the eight (8) strain gages 34, 36, 38 are then transmitted to a preamplifier board (not shown) for preconditioning. The preamplifier board is used to increase the magnitudes of the analog voltage signals, and preferably, to convert the analog voltage signals into digital voltage signals as well. After which, the load transducer 10 transmits the output signals STO1-STO8 to a main signal amplifier/converter 40. Depending on whether the preamplifier board also includes an analog-to-digital (A/D) converter, the output signals STO1-STO8 could be either in the form of analog signals or digital signals. The main signal amplifier/converter 40 further magnifies the transducer output signals STO1-STO8, and if the signals STO1-STO8 are of the analog-type (for a case where the preamplifier board did not include an analog-to-digital (A/D) converter), it may also convert the analog signals to digital signals. Then, the signal amplifier/converter 40 transmits either the digital or analog signals SACO1-SACO8 to the data acquisition/data processing device 42 (computer 42) so that the forces and/or moments that are being applied to the load transducer 10 can be transformed into output load values OL. The computer or data acquisition/data processing device 42 may further comprise an analog-to-digital (A/D) converter if the signals SACO1-SACO8 are in the form of analog signals. In such a case, the analog-to-digital converter will convert the analog signals into digital signals for processing by the microprocessor of the computer 42.
When the computer or data acquisition/data processing device 42 receives the voltage signals SACO1-SACO8, it initially transforms the signals into output forces and/or moments by multiplying the voltage signals SACO1-SACO8 by a calibration matrix. After which, the force components FX, FY, FZ and the moment components MX, MY, MZ applied to the load transducer 10 are determined by the computer or data acquisition/data processing device 42. Also, the center of pressure (i.e., the x and y coordinates of the point of application of the force applied to the load transducer 10) can be determined by the computer or data acquisition/data processing device 42.
FIGS. 6-9 illustrate a load transducer 10′ according to a second exemplary embodiment of the present invention. With reference to these figures, it can be seen that, in some respects, the second exemplary embodiment is similar to that of the first embodiment. Moreover, some parts are common to both such embodiments. For the sake of brevity, the parts that the second embodiment of the load transducer has in common with the first embodiment will only be briefly mentioned, if at all, because these components have already been explained in detail above. Furthermore, in the interest of clarity, these components will be denoted using the same reference characters that were used in the first embodiment.
Initially, referring to the perspective view of FIG. 6, it can be seen that, like the first exemplary embodiment, the transducer frame 12′ of the second embodiment includes a central body portion 14 and a plurality of beams 16, 18, 20′, 24′, 28, 30 extending outwardly therefrom. Although, unlike the first exemplary embodiment of the load transducer, the side 14b of the body portion 14 of the load transducer 10′ contains only a single beam 20′ extending therefrom, rather two beams 20, 22 (see FIG. 1). Similarly, unlike the load transducer 10 of the first embodiment, the side 14c of the body portion 14 of the load transducer 10′ contains only a single beam 24′ extending therefrom, rather two beams 24, 26 (refer to FIG. 1). Also, unlike the load transducer 10 of the first embodiment, the load transducer 10′ includes only three strain gages 34 that are sensitive to the vertical force component (i.e., three Fz strain gages), rather than four strain gages.
In particular, in the second embodiment, beams 16, 18, 24′ each comprise a strain gage 34 disposed on the top surface thereof that is sensitive to the vertical force component (i.e., a Fz strain gage). Beams 18, 24′ also each comprise a strain gage 36 disposed on a side surface thereof that is sensitive to a first shear force component (i.e., a Fx strain gage), while beams 20′, each comprise a strain gage 38 disposed on a side surface thereof that is sensitive to a second shear force component (i.e., a FY strain gage). The load transducer 10′ of the second embodiment is capable of measuring the three force components (FX, FY, FZ) and the three moment components (MX, MY, MZ) with a minimum of six beams 16, 18, 20′, 24′, 28, 30 (i.e., three input beams and three output beams) and a minimum of seven strain gages 34, 36, 38.
Now, with reference to the top view illustrated in FIG. 9, it can be seen that the central longitudinal axis LA5 of the beam 20′, which extends from side 14b of the body portion 14, is generally equally spaced apart from the central longitudinal axis LA3 and LA4 (i.e., the central longitudinal axis LA5 of the beam 20′ is generally centered between the central longitudinal axis LA3 of beam 30 and the central longitudinal axis LA4 of beam 28). Similarly, as shown in FIG. 9, the longitudinal axis LA6 of the beam 24′, which extends from side 14c of the body portion 14, is generally equally spaced apart from the central longitudinal axis LA1 and LA2 (i.e., the central longitudinal axis LA6 of the beam 24′ is generally centered between the central longitudinal axis LA1 of beam 16 and the central longitudinal axis LA2 of beam 18). The other features of the load transducer 10′ are similar to that of the load transducer 10, and thus, need not be reiterated herein.
FIGS. 10-14 illustrate a load transducer 100 according to a third exemplary embodiment of the present invention. Referring initially to the perspective view of FIG. 10, it can be seen that the load transducer 100 generally includes a one-piece compact transducer frame 112 having a central body portion 114 and a plurality of generally U-shaped transducer beams 116, 118, 120, 122 extending outwardly from the central body portion 114. As best illustrated in FIG. 10, each of the beams 116, 118, 120, 122 comprises a plurality of load cells or transducer elements for measuring forces and/or moments.
With reference again to FIG. 10, it can be seen that the illustrated central body portion 114 is generally in the form of square band-shaped element with a central opening 102 disposed therethrough. In FIG. 10, it can be seen that the body portion 114 comprises a first pair of opposed sides 114a, 114c and a second pair of opposed sides 114b, 114d. The side 114a is disposed generally parallel to the side 114c, while the side 114b is disposed generally parallel to the side 114d. Each of the sides 114a, 114b, 114c, 114d is disposed generally perpendicular to the planar top and bottom surfaces of the body portion 114. Also, each of the first pair of opposed sides 114a, 114c is disposed generally perpendicular to each of the second pair of opposed sides 114b, 114d. In addition, as shown in FIG. 10, each of the opposed sides 114a, 114c comprises a beam connecting portion 128 extending outward therefrom. In the illustrated embodiment, it can be seen that each of the beam connecting portions 128 comprises a plurality of apertures 130 (e.g., two apertures 130) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 100 to another object, such as a robotic arm, etc. Also, as depicted in the side views of FIGS. 11 and 12 and the bottom view of FIG. 14, the bottom surface of the central body portion 114 comprises a raised portion or standoff portion 126 for elevating the transducer beams 116, 118, 120, 122 above the object (e.g., robotic arm) to which the load transducer 100 is attached so that forces and/or moments are capable of being accurately measured by the load transducer 100. In one or more embodiments, the structural components to which the load transducer 100 is mounted are connected only to the top standoff portions 124 and the bottom standoff 126 so as to ensure that the total load applied to the load transducer 100 is transmitted through the transducer beams 116, 118, 120, 122.
As shown in FIGS. 10-14, the illustrated generally U-shaped transducer beams 116, 118, 120, 122 are each attached to one of the sides 114a, 114b, 114c, 114d of the body portion 114 via a connecting portion 128, and extend generally horizontally outward therefrom. In particular, beams 116, 118 extend generally horizontally outward from opposed sides of the beam connecting portion 128 attached to side 114a of the body portion 114, while the beams 120, 122 extend generally horizontally outward from opposed sides of the beam connecting portion 128 attached to side 114c of the body portion 114. As best shown in FIG. 10, the top and bottom surfaces of each of the illustrated beams 116, 118, 120, 122 are disposed substantially co-planar with the top and bottom surfaces of the body portion 114. Each of the illustrated beams 116, 118, 120, 122 has a U-shaped cantilevered end relative to the body portion 114 that allows for deflection of the ends of the beams in multiple directions.
With particular reference to FIGS. 10, 13, and 14, it can be seen that each of the generally U-shaped beams 116, 118, 120, 122 comprises a plurality of segmental beam portions, wherein each of the successive beam portions are disposed substantially perpendicular to the immediately preceding beam portion. For example, as shown in FIG. 10, the first generally U-shaped transducer beam 116 comprises a first beam portion 116a extending from a first side of the beam connecting portion 128, a second beam portion 116b connected to the first beam portion 116a and disposed substantially perpendicular thereto, a third beam portion 116c connected to the second beam portion 116b and disposed substantially perpendicular thereto, and a fourth beam portion 116d connected to the third beam portion 116c and disposed substantially perpendicular thereto. Similarly, the second generally U-shaped transducer beam 118 comprises a first beam portion 118a extending from a second side of the beam connecting portion 128 (which is generally opposite to the first side of the beam connecting portion 128 from which the first beam portion 116a extends), a second beam portion 118b connected to the first beam portion 118a and disposed substantially perpendicular thereto, a third beam portion 118c connected to the second beam portion 118b and disposed substantially perpendicular thereto, and a fourth beam portion 118d connected to the third beam portion 118c and disposed substantially perpendicular thereto. With reference to FIGS. 10, 13, and 14, it can be seen that the generally U-shaped transducer beams 120, 122 are generally minor images of the generally U-shaped transducer beams 116, 118, and thus, have the same structure as the generally U-shaped transducer beams 116, 118. Referring again to FIGS. 10, 13, and 14, it can be seen that the fourth beam portion of each of the generally U-shaped transducer beams 116, 118, 120, 122 comprises a raised portion or standoff portion 124 with mounting apertures 132 (e.g., two apertures 132) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 100 to another object, such as a robotic arm, etc. In addition, as shown in FIGS. 10 and 13, each generally U-shaped transducer beam 116, 118, 120, 122 comprises a central beam gap 106, which is bounded by the second, third, and fourth beam portions. Also, it can be seen that the first and second beam portions of each transducer beam 116, 118, 120, 122 are separated from the opposing sides of the central body portion 114 by an L-shaped gap 104. That is, the sides of the central body portion 114, which face the sides of the first and second beam portions in an opposing relationship, are separated from the sides of the first and second beam portions by the L-shaped gap 104.
As best shown in the perspective view of FIG. 10, the illustrated load cells are located on the transducer beams 116, 118, 120, 122. In the illustrated embodiment, each load cell comprises a plurality of strain gages 134, 136, 138. Specifically, in the illustrated embodiment, each of the first portions (e.g., 116a, 118a) of the transducer beams 116, 118, 120, 122 comprise a strain gage 134 disposed on the top surface thereof that is sensitive to the vertical force component (i.e., a Fz strain gage). The first portions (e.g., 116a, 118a) of the transducer beams 116, 118, 120, 122 also each comprise a strain gage 138 disposed on a side surface thereof that is sensitive to a first shear force component (i.e., a Fy strain gage). Also, in the illustrated embodiment, each of the fourth portions (e.g., 116d, 118d) of the transducer beams 116, 118, 120, 122 comprise a strain gage 136 disposed on a side surface thereof that is sensitive to a second shear force component (i.e., a FX strain gage).
As best shown in FIG. 10, the illustrated load cells are configured as bending beam load cells. The illustrated strain gages 134, 136, 138 are mounted to either top or side surfaces of the beams 116, 118, 120, 122 between their attachment locations to the beam connecting portions 128 and the raised end portions 124 thereof. Alternatively, the strain gages 134 can be mounted to the bottom surfaces of the first beam portions (e.g., 116a, 118a) of the transducer beams 116, 118, 120, 122, while the strain gages 138 can be mounted to the opposite side surfaces of the first beam portions (e.g., 116a, 118a) of the transducer beams 116, 118, 120, 122. Similarly, the strain gages 136 can be mounted to the opposite side surfaces of the fourth beam portions (e.g., 116d, 118d) of the transducer beams 116, 118, 120, 122. In general, the strain gages 134, 136, 138 are mounted to surfaces generally normal to the direction of applied vertical and/or shear forces (i.e., FX, FY, FZ). It is also noted that alternatively, the strain gages 134 can be mounted at both the top surface and the bottom surface of the first beam portions of the beams 116, 118, 120, 122, the strain gages 138 can be mounted at both opposed side surfaces of first beam portions of the beams 116, 118, 120, 122, and/or the strain gages 136 can be mounted at both opposed side surfaces of the beams 116, 118, 120, 122. These strain gages 134, 136, 138 measure force either by bending moment or difference of bending moments at two cross sections. As force is applied to the ends of the beams, the beams 116, 118, 120, 122 bend. This bending either stretches or compresses the strain gages 134, 136, 138, which in turn changes the resistance of the electrical current passing therethrough. The amount of change in the electrical voltage or current is proportional to the magnitude of the applied force, as applied to the ends of respective beams 116, 118, 120, 122.
Next, referring to FIGS. 15-18, a load transducer 200 according to a fourth exemplary embodiment of the present invention will be described. Referring initially to the perspective view of FIG. 15, it can be seen that the load transducer 200 generally includes a one-piece compact transducer frame 204 that is generally in the form of square band-shaped element with a central opening 202 disposed therethrough. As best illustrated in FIGS. 15 and 18, the square band-shaped transducer frame 204 comprises a first transducer beam side portion 206, a second transducer beam side portion 208, a third transducer beam side portion 210, and a fourth transducer beam side portion 212. Also, as shown in FIG. 15, the transducer beam side portions 206, 208, 210, 212 comprise a plurality of load cells or transducer elements for measuring forces and/or moments. The transducer frame 204 of the load transducer 200 is similar to the other transducers (e.g., transducers 300, 400) that will be described hereinafter, except that the central body portion of these transducers (e.g., 300, 400) has been removed in the load transducer 200.
As shown in FIGS. 15-18, the illustrated transducer beam side portions 206, 208, 210, 212 of the transducer frame 204 are arranged in a generally square configuration. In particular, with reference to FIGS. 15 and 18, the first transducer beam side portion 206 is connected to the second transducer beam side portion 208 on one of its longitudinal ends, and the fourth transducer beam side portion 212 on the other one of its longitudinal ends, and the first transducer beam side portion 206 is disposed generally perpendicular to each of the second and fourth transducer beam side portions 208, 212. The second transducer beam side portion 208 is connected to the first transducer beam side portion 206 on one of its longitudinal ends, and the third transducer beam side portion 210 on the other one of its longitudinal ends, and the second transducer beam side portion 208 is disposed generally perpendicular to each of the first and third transducer beam side portions 206, 210. The third transducer beam side portion 210 is connected to the second transducer beam side portion 208 on one of its longitudinal ends, and the fourth transducer beam side portion 212 on the other one of its longitudinal ends, and the third transducer beam side portion 210 is disposed generally perpendicular to each of the second and fourth transducer beam side portions 208, 212. The fourth transducer beam side portion 212 is connected to the third transducer beam side portion 210 on one of its longitudinal ends, and the first transducer beam side portion 206 on the other one of its longitudinal ends, and the fourth transducer beam side portion 212 is disposed generally perpendicular to each of the first and third transducer beam side portions 206, 210. Referring to FIGS. 15, 17, and 18, it can be seen that the top surface of the second transducer beam side portion 208 and the top surface of the fourth transducer beam side portion 212 each comprises a central raised portion or standoff portion 214 with spaced apart mounting apertures 218 (e.g., two spaced apart apertures 218) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 200 to another object, such as a robotic arm, etc. Similarly, with reference to FIGS. 15 and 16, it can be seen that the bottom surface of the first transducer beam side portion 206 and the bottom surface of the third transducer beam side portion 210 each comprises a central raised portion or standoff portion 216 with spaced apart mounting apertures 218 (e.g., two spaced apart apertures 218) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 200 to another object, such as a robotic arm, etc.
As best shown in the perspective view of FIG. 15, the illustrated load cells are located on the transducer beam side portions 206, 208, 210, 212. In the illustrated embodiment, each load cell comprises one or more strain gages 220, 222, 224. Specifically, in the illustrated embodiment, the first transducer beam side portion 206 and the third transducer beam side portion 210 each comprise a plurality of spaced apart strain gages 220 (e.g., two spaced apart strain gages 220) disposed on the top surface thereof that is sensitive to the vertical force component (i.e., a FZ strain gage). The second transducer beam side portion 208 and the fourth transducer beam side portion 212 also each comprise a plurality of spaced apart strain gages 222 (e.g., two spaced apart strain gages 222) disposed on a side surface thereof that is sensitive to a first shear force component (i.e., a FX strain gage). Also, in the illustrated embodiment, the first transducer beam side portion 206 and the third transducer beam side portion 210 also each comprise a plurality of spaced apart strain gages 224 (e.g., two spaced apart strain gages 224) disposed on a side surface thereof that is sensitive to a second shear force component (i.e., a FY strain gage).
As best shown in FIG. 15, the illustrated load cells are configured as bending beam load cells. The illustrated strain gages 220, 222, 224 are mounted to either top or side surfaces of the transducer beam side portions 206, 208, 210, 212 between the opposed longitudinal ends thereof. Alternatively, the strain gages 220 can be mounted to the bottom surfaces of the first and third transducer beam side portions 206, 210, while the strain gages 222 can be mounted to the opposite side surfaces of the second and fourth transducer beam side portions 208, 212. Similarly, the strain gages 224 can be mounted to the opposite side surfaces of the first and third transducer beam side portions 206, 210. In general, the strain gages 220, 222, 224 are mounted to surfaces generally normal to the direction of applied vertical and/or shear forces (i.e., FX, FY, FZ). It is also noted that alternatively, the strain gages 220 can be mounted at both the top surface and the bottom surface of the first and third transducer beam side portions 206, 210, the strain gages 222 can be mounted at both opposed side surfaces of second and fourth transducer beam side portions 208, 212, and/or the strain gages 224 can be mounted at both opposed side surfaces of the first and third transducer beam side portions 206, 210. These strain gages 220, 222, 224 measure force either by bending moment or difference of bending moments at two cross sections. As force is applied to the beams, the beams 206, 208, 210, 212 bend. This bending either stretches or compresses the strain gages 220, 222, 224, which in turn changes the resistance of the electrical current passing therethrough. The amount of change in the electrical voltage or current is proportional to the magnitude of the applied force, as transferred through the end portions of respective beams 206, 208, 210, 212.
An exemplary mounting arrangement for the load transducer 200 is illustrated in FIG. 25. As depicted in the perspective view of FIG. 25, the load transducer 200 is mounted between a top plate member 226 and a bottom plate member 228. Specifically, in this mounting arrangement, the bottom surface 226a of the top plate member 226 abuts the top surfaces of the standoff portions 214 on the second and fourth transducer beam side portions 208, 212, while the top surface 228a of the bottom plate member 228 abuts the bottom surfaces of the standoff portions 216 on the first and third transducer beam side portions 206, 210. As such, in this mounting arrangement, an upper gap 230 is formed between the top surfaces of the load transducer 200 and the bottom surface 226a of the top plate member 226 by the two spaced apart top standoff portions 214. Similarly, a lower gap 232 is formed between the bottom surfaces of the load transducer 200 and the top surface 228a of the bottom plate member 228 by the two spaced apart bottom standoff portions 216. Thus, as result of the mounting arrangement illustrated in FIG. 25, the entire load exerted on the load transducer 200 by the top and bottom plate members 226, 228 is transferred through the corner portions of the transducer frame 204, which are instrumented with the strain gages 220, 222, 224 and are spaced apart from the top and bottom plate members 226, 228 by the standoff portions 214, 216.
While the exemplary mounting arrangement is illustrated in FIG. 25 using the load transducer 200, it is to be understood that each of the other load transducers 10, 10′, 100, 300, 400, 500, 600, 700, 800 described herein are mounted in generally the same manner to adjoining structures (e.g., plate members 226, 228 or components of a robotic arm). That is, the standoff portions described on the load transducers 10, 10′, 100, 300, 400, 500, 600, 700, 800 perform the same functions as those described in conjunction with the load transducer 200 above. In particular, the adjoining structures to which the transducers are mounted are only connected to the top standoff portions and the bottom standoff portions of each load transducer 10, 10′, 100, 300, 400, 500, 600, 700, 800 so as to ensure that the total loads applied to the load transducers 10, 10′, 100, 300, 400, 500, 600, 700, 800 are transmitted through the instrumented portions of the transducer beams of the transducers.
FIG. 19 illustrates a load transducer 300 according to a fifth exemplary embodiment of the present invention. With reference to this figure, it can be seen that, in some respects, the fifth exemplary embodiment is similar to that of the fourth embodiment. Moreover, some parts are common to both such embodiments. For the sake of brevity, the parts that the fifth embodiment of the load transducer has in common with the fourth embodiment will only be briefly mentioned because these components have already been explained in detail above.
Initially, referring to the perspective view of FIG. 19, it can be seen that, unlike the fourth exemplary embodiment of the load transducer, the load transducer 300 comprises a central body portion 302. Also, unlike the load transducer 200 of the fourth embodiment, the second and fourth transducer beam side portions 308, 312 have side projecting portions 326 extending from the inner sides thereof towards the central body portion 302. As shown in FIG. 19, the load transducer 300 generally includes a one-piece compact transducer frame 304 with a central body portion 302 and a plurality of transducer beam side portions 306, 308, 310, 312.
With reference again to FIG. 19, it can be seen that the illustrated central body portion 302 is generally in the form of rectangular band-shaped element with a central opening 303 disposed therethrough. In FIG. 19, it can be seen that the body portion 302 comprises a first pair of opposed side portions 302a, 302c and a second pair of opposed side portions 302b, 302d. The side portion 302a is disposed generally parallel to the side portion 302c, while the side portion 302b is disposed generally parallel to the side portion 302d. Each of the side surfaces of the side portions 302a, 302b, 302c, 302d is disposed generally perpendicular to the planar top and bottom surfaces thereof. Also, each of the first pair of opposed side portions 302a, 302c is disposed generally perpendicular to each of the second pair of opposed sides portions 302b, 302d. In addition, as shown in FIG. 19, each of the opposed side portions 302a, 302c forms a middle portion of the first and third transducer beam side portions 306, 310. In the illustrated embodiment, it can be seen that each of the opposed side portions 302a, 302c comprises a plurality of apertures 318 (e.g., two apertures 318) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 300 to another object, such as a robotic arm, etc. Also, as depicted in the FIG. 19, the central body portion 302 comprises a raised top portion or top standoff portion 314 for spacing the transducer beam side portions 306, 308, 310, 312 apart from the object (e.g., robotic arm) to which the load transducer 300 is attached so that forces and/or moments are capable of being accurately measured by the load transducer 300.
As shown in FIG. 19, the illustrated transducer beam side portions 306, 308, 310, 312 of the transducer frame 304 are arranged in a generally square configuration. In particular, with reference to FIG. 19, the first transducer beam side portion 306 is connected to the second transducer beam side portion 308 on one of its longitudinal ends, and the fourth transducer beam side portion 312 on the other one of its longitudinal ends, and the first transducer beam side portion 306 is disposed generally perpendicular to each of the second and fourth transducer beam side portions 308, 312. The second transducer beam side portion 308 is connected to the first transducer beam side portion 306 on one of its longitudinal ends, and the third transducer beam side portion 310 on the other one of its longitudinal ends, and the second transducer beam side portion 308 is disposed generally perpendicular to each of the first and third transducer beam side portions 306, 310. The third transducer beam side portion 310 is connected to the second transducer beam side portion 308 on one of its longitudinal ends, and the fourth transducer beam side portion 312 on the other one of its longitudinal ends, and the third transducer beam side portion 310 is disposed generally perpendicular to each of the second and fourth transducer beam side portions 308, 312. The fourth transducer beam side portion 312 is connected to the third transducer beam side portion 310 on one of its longitudinal ends, and the first transducer beam side portion 306 on the other one of its longitudinal ends, and the fourth transducer beam side portion 312 is disposed generally perpendicular to each of the first and third transducer beam side portions 306, 310. Referring to FIG. 19, it can be seen that the bottom surface of the second transducer beam side portion 308 and the bottom surface of the fourth transducer beam side portion 312 each comprises a central standoff portion 316, which is connected to the side projecting portion 326 on each of the transducer beam side portions 308, 312. The side projecting portions 326 each comprise spaced apart mounting apertures 328 (e.g., two spaced apart apertures 328) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 300 to another object, such as a robotic arm, etc.
As best shown in the perspective view of FIG. 19, the illustrated load cells are located on the transducer beam side portions 306, 308, 310, 312. In the illustrated embodiment, each load cell comprises one or more strain gages 320, 322, 324. Specifically, in the illustrated embodiment, the second transducer beam side portion 308 and the fourth transducer beam side portion 312 each comprise a plurality of spaced apart strain gages 320 (e.g., two spaced apart strain gages 320) disposed on the top surface thereof that is sensitive to the vertical force component (i.e., a FZ strain gage). The second transducer beam side portion 308 and fourth transducer beam side portion 312 also each comprise a plurality of spaced apart strain gages 322 (e.g., two spaced apart strain gages 322) disposed on a side surface thereof that is sensitive to a first shear force component (i.e., a FX strain gage). Also, in the illustrated embodiment, the first transducer beam side portion 306 and the third transducer beam side portion 310 also each comprise a plurality of spaced apart strain gages 324 (e.g., two spaced apart strain gages 324) disposed on a side surface thereof that is sensitive to a second shear force component (i.e., a FY strain gage).
FIG. 20 illustrates a load transducer 400 according to a sixth exemplary embodiment of the present invention. With reference to this figure, it can be seen that, in some respects, the sixth exemplary embodiment is similar to that of the fifth embodiment. Moreover, some parts are common to both such embodiments. For the sake of brevity, the parts that the sixth embodiment of the load transducer has in common with the fifth embodiment will only be briefly mentioned because these components have already been explained in detail above.
Initially, referring to the perspective view of FIG. 20, it can be seen that, unlike the fifth exemplary embodiment of the load transducer, all four sides of the central body portion 402 of the load transducer 400 are spaced apart from the transducer beam side portions 406, 408, 410, 412. In particular, the central body portion 402 is spaced apart from the transducer beam side portions 406, 408, 410, 412 by the two C-shaped gaps 426. Also, unlike the load transducer 300 of the fifth embodiment, the first and third transducer beam side portions 406, 410 of the load transducer 400 are connected to the central body portion 402 by the beam connecting portions 417. Although, like the load transducer 300, the load transducer 400 generally includes a one-piece compact transducer frame 404 with a central body portion 402 and a plurality of transducer beam side portions 406, 408, 410, 412.
With reference again to FIG. 20, it can be seen that the illustrated central body portion 402 is generally in the form of rectangular band-shaped element with a central opening 403 disposed therethrough. In FIG. 20, it can be seen that the body portion 402 comprises a first pair of opposed side portions 402a, 402c and a second pair of opposed side portions 402b, 402d. The side portion 402a is disposed generally parallel to the side portion 402c, while the side portion 402b is disposed generally parallel to the side portion 402d. Each of the side surfaces of the side portions 402a, 402b, 402c, 402d is disposed generally perpendicular to the planar top and bottom surfaces thereof. Also, each of the first pair of opposed side portions 402a, 402c is disposed generally perpendicular to each of the second pair of opposed sides portions 402b, 402d. In addition, as shown in FIG. 20, each of the opposed side portions 402a, 402c is connected to the first and third transducer beam side portions 406, 410 by beam connecting portions 417. In the illustrated embodiment, it can be seen that each of the beam connecting portions 417 comprises a plurality of apertures 418 (e.g., two apertures 418) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 400 to another object, such as a robotic arm, etc.
As shown in FIG. 20, the illustrated transducer beam side portions 406, 408, 410, 412 of the transducer frame 404 are arranged in a generally square configuration. In particular, with reference to FIG. 20, the first transducer beam side portion 406 is connected to the second transducer beam side portion 408 on one of its longitudinal ends, and the fourth transducer beam side portion 412 on the other one of its longitudinal ends, and the first transducer beam side portion 406 is disposed generally perpendicular to each of the second and fourth transducer beam side portions 408, 412. The second transducer beam side portion 408 is connected to the first transducer beam side portion 406 on one of its longitudinal ends, and the third transducer beam side portion 410 on the other one of its longitudinal ends, and the second transducer beam side portion 408 is disposed generally perpendicular to each of the first and third transducer beam side portions 406, 410. The third transducer beam side portion 410 is connected to the second transducer beam side portion 408 on one of its longitudinal ends, and the fourth transducer beam side portion 412 on the other one of its longitudinal ends, and the third transducer beam side portion 410 is disposed generally perpendicular to each of the second and fourth transducer beam side portions 408, 412. The fourth transducer beam side portion 412 is connected to the third transducer beam side portion 410 on one of its longitudinal ends, and the first transducer beam side portion 406 on the other one of its longitudinal ends, and the fourth transducer beam side portion 412 is disposed generally perpendicular to each of the first and third transducer beam side portions 406, 410. Referring to FIG. 20, it can be seen that the top surface of the second transducer beam side portion 408 and the top surface of the fourth transducer beam side portion 412 each comprises a central raised portion or standoff portion 414 with spaced apart mounting apertures 428 (e.g., two spaced apart apertures 428) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 400 to another object, such as a robotic arm, etc. Similarly, with reference to FIG. 20, it can be seen that the bottom surface of the first transducer beam side portion 406 and the bottom surface of the third transducer beam side portion 410 each comprises a central raised portion or standoff portion 416.
As best shown in the perspective view of FIG. 20, the illustrated load cells are located on the transducer beam side portions 406, 408, 410, 412. In the illustrated embodiment, each load cell comprises one or more strain gages 420, 422, 424. Specifically, in the illustrated embodiment, the first transducer beam side portion 406 and the third transducer beam side portion 410 each comprise a plurality of spaced apart strain gages 420 (e.g., two spaced apart strain gages 420) disposed on the top surface thereof that is sensitive to the vertical force component (i.e., a FZ strain gage). The second transducer beam side portion 408 and fourth transducer beam side portion 412 also each comprise a plurality of spaced apart strain gages 422 (e.g., two spaced apart strain gages 422) disposed on a side surface thereof that is sensitive to a first shear force component (i.e., a FX strain gage). Also, in the illustrated embodiment, the first transducer beam side portion 406 and the third transducer beam side portion 410 also each comprise a plurality of spaced apart strain gages 424 (e.g., two spaced apart strain gages 424) disposed on a side surface thereof that is sensitive to a second shear force component (i.e., a FY strain gage).
FIG. 21 illustrates a load transducer 500 according to a seventh exemplary embodiment of the present invention. With reference to this figure, it can be seen that, in some respects, the seventh exemplary embodiment is similar to that of the fifth embodiment. Moreover, some parts are common to both such embodiments. For the sake of brevity, the parts that the seventh embodiment of the load transducer has in common with the fifth embodiment will only be briefly mentioned because these components have already been explained in detail above.
Initially, referring to the perspective view of FIG. 21, it can be seen that, like the fifth embodiment described above, the load transducer 500 generally includes a one-piece compact transducer frame 504 with a central body portion 502 and a plurality of transducer beam side portions 506, 508, 510, 512, 514, 516. Although, the central body portion 502 of the load transducer 500 is considerably wider than the central body portion 302 of the load transducer 300.
With reference again to FIG. 21, it can be seen that the illustrated central body portion 502 is generally in the form of square band-shaped element with a central opening 530 disposed therethrough. In FIG. 21, it can be seen that the body portion 502 comprises a first pair of opposed side portions 502a, 502c and a second pair of opposed side portions 502b, 502d. The side portion 502a is disposed generally parallel to the side portion 502c, while the side portion 502b is disposed generally parallel to the side portion 502d. Each of the side surfaces of the side portions 502a, 502b, 502c, 502d is disposed generally perpendicular to the planar top and bottom surfaces thereof. Also, each of the first pair of opposed side portions 502a, 502c is disposed generally perpendicular to each of the second pair of opposed sides portions 502b, 502d. In addition, as shown in FIG. 21, each of the opposed side portions 502a, 502c is disposed between a respective pair of transducer beam side portions 506, 508 and 512, 514. In the illustrated embodiment, it can be seen that each of the opposed side portions 502a, 502c comprises a plurality of apertures 532 (e.g., two apertures 532) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 500 to another object, such as a robotic arm, etc. Also, as depicted in the FIG. 21, the central body portion 502 comprises a raised bottom portion or bottom standoff portion 520 for spacing the transducer beam side portions 506, 508, 510, 512, 514, 516 apart from the object (e.g., robotic arm) to which the load transducer 500 is attached so that forces and/or moments are capable of being accurately measured by the load transducer 500.
As shown in FIG. 21, the first set of illustrated transducer beam side portions 506, 514, 516 of the transducer frame 504 are arranged in a generally C-shaped configuration on a first side of the central body portion 502. A first side aperture 534 is formed between the side portion 502d of the central body portion 502 and the first set of transducer beam side portions 506, 514, 516. Referring again to FIG. 21, it can be seen that the first transducer beam side portion 506 is connected to the sixth transducer beam side portion 516 on one of its longitudinal ends, and the side portion 502d of the central body portion 502 on the other one of its longitudinal ends, and the first transducer beam side portion 506 is disposed generally perpendicular to the side portion 502d of the central body portion 502 and to sixth transducer beam side portion 516. Similarly, the fifth transducer beam side portion 514 is connected to the sixth transducer beam side portion 516 on one of its longitudinal ends, and the side portion 502d of the central body portion 502 on the other one of its longitudinal ends, and the fifth transducer beam side portion 514 is disposed generally perpendicular to the side portion 502d of the central body portion 502 and to sixth transducer beam side portion 516. The sixth transducer beam side portion 516 is connected to the first transducer beam side portion 506 on one of its longitudinal ends, and the fifth transducer beam side portion 514 on the other one of its longitudinal ends, and the sixth transducer beam side portion 516 is disposed generally perpendicular to each of the first and fifth transducer beam side portions 506, 514. Turning again to FIG. 21, it can be seen that the second set of transducer beam side portions 508, 510, 512 of the transducer frame 504 is arranged in a generally C-shaped configuration on a second side of the central body portion 502, which is opposite to the first side of the central body portion 502. A second side aperture 534 is formed between the side portion 502b of the central body portion 502 and the second set of transducer beam side portions 508, 510, 512. In FIG. 21, it can be seen that the second transducer beam side portion 508 is connected to the third transducer beam side portion 510 on one of its longitudinal ends, and the side portion 502b of the central body portion 502 on the other one of its longitudinal ends, and the second transducer beam side portion 508 is disposed generally perpendicular to the side portion 502b of the central body portion 502 and to third transducer beam side portion 510. Similarly, the fourth transducer beam side portion 512 is connected to the third transducer beam side portion 510 on one of its longitudinal ends, and the side portion 502b of the central body portion 502 on the other one of its longitudinal ends, and the fourth transducer beam side portion 512 is disposed generally perpendicular to the side portion 502b of the central body portion 502 and to third transducer beam side portion 510. The third transducer beam side portion 510 is connected to the second transducer beam side portion 508 on one of its longitudinal ends, and the fourth transducer beam side portion 512 on the other one of its longitudinal ends, and the third transducer beam side portion 510 is disposed generally perpendicular to each of the second and fourth transducer beam side portions 508, 512. Also, as shown in FIG. 21, it can be seen that the top surface of the third transducer beam side portion 510 and the top surface of the sixth transducer beam side portion 516 each comprises a central standoff portion 518. The central standoff portions 518 each comprise spaced apart mounting apertures 522 (e.g., two spaced apart apertures 522) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 500 to another object, such as a robotic arm, etc.
As best shown in the perspective view of FIG. 21, the illustrated load cells are located on the transducer beam side portions 506, 508, 510, 512, 514, 516. In the illustrated embodiment, each load cell comprises one or more strain gages 524, 526, 528. Specifically, in the illustrated embodiment, the first transducer beam side portion 506, the second transducer beam side portion 508, the fourth transducer beam side portion 512, and the fifth transducer beam side portion 514 each comprise a strain gage 524 disposed on the top surface thereof that is sensitive to the vertical force component (i.e., a FZ strain gage). The third transducer beam side portion 510 and the sixth transducer beam side portion 516 also each comprise a plurality of spaced apart strain gages 526 (e.g., two spaced apart strain gages 526) disposed on a side surface thereof that is sensitive to a first shear force component (i.e., a FX strain gage). Also, in the illustrated embodiment, the first transducer beam side portion 506, the second transducer beam side portion 508, the fourth transducer beam side portion 512, and the fifth transducer beam side portion 514 each comprises a strain gage 528 disposed on an outer side surface thereof that is sensitive to a second shear force component (i.e., a FY strain gage).
FIG. 22 illustrates a load transducer 600 according to an eighth exemplary embodiment of the present invention. With reference to this figure, it can be seen that, in some respects, the eighth exemplary embodiment is similar to that of the preceding embodiments. Moreover, some parts are common to all of the embodiments. For the sake of brevity, the parts that the eighth embodiment of the load transducer has in common with the preceding embodiments will only be briefly mentioned because these components have already been explained in detail above.
Initially, referring to the perspective view of FIG. 22, it can be seen that, like the preceding embodiments described above, the load transducer 600 generally includes a one-piece compact transducer frame 604 with a central body portion 602 and a plurality of transducer beams 606, 608, 610, 612, 614, 616 connected thereto. Although, the transducer beams 606, 608, 610, 612, 614, 616 are arranged in a different configuration than that which was described for the preceding embodiments.
With reference again to FIG. 22, it can be seen that the illustrated central body portion 602 is generally in the form of square band-shaped element with a central opening 630 disposed therethrough. In FIG. 22, it can be seen that the body portion 602 comprises a first pair of opposed side portions 602a, 602c and a second pair of opposed side portions 602b, 602d. The side portion 602a is disposed generally parallel to the side portion 602c, while the side portion 602b is disposed generally parallel to the side portion 602d. Each of the side surfaces of the side portions 602a, 602b, 602c, 602d is disposed generally perpendicular to the planar top and bottom surfaces thereof. Also, each of the first pair of opposed side portions 602a, 602c is disposed generally perpendicular to each of the second pair of opposed sides portions 602b, 602d. In addition, as shown in FIG. 22, each of the opposed side portions 602b, 602d is connected to a respective set of transducer beams 606, 608, 610 and 612, 614, 616. In the illustrated embodiment, it can be seen that each of the opposed side portions 602a, 602c comprises a plurality of apertures 632 (e.g., two apertures 632) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 600 to another object, such as a robotic arm, etc.
As shown in FIG. 22, the first set of illustrated transducer beams 606, 608, 610 of the transducer frame 604 is arranged in a generally T-shaped configuration on a first side of the central body portion 602. A first side aperture 634 is formed between the side portion 602d of the central body portion 602 and the first set of transducer beam side portions 606, 608, 610. Referring again to FIG. 22, it can be seen that the first transducer beam 606 is connected to the side portion 602d of the central body portion 602 by means of two spaced apart connecting transducer beams 608, 610. Specifically, the second transducer beam 608 is connected to an inner side of the first transducer beam 606 on one of its longitudinal ends, and the side portion 602d of the central body portion 602 on the other one of its longitudinal ends, and the second transducer beam 608 is disposed generally perpendicular to the side portion 602d of the central body portion 602 and to first transducer beam 606. Similarly, the third transducer beam 610 is connected to the inner side of the first transducer beam 606 on one of its longitudinal ends, and the side portion 602d of the central body portion 602 on the other one of its longitudinal ends, and the third transducer beam 610 is disposed generally perpendicular to the side portion 602d of the central body portion 602 and to first transducer beam 606. Turning again to FIG. 22, it can be seen that the second set of transducer beams 612, 614, 616 of the transducer frame 604 is arranged in a generally T-shaped configuration on a second side of the central body portion 602, which is opposite to the first side of the central body portion 602. A second side aperture 634 is formed between the side portion 602b of the central body portion 602 and the second set of transducer beam side portions 612, 614, 616. In FIG. 22, similar to the first transducer beam 606, it can be seen that the fourth transducer beam 612 is connected to the side portion 602b of the central body portion 602 by means of two spaced apart connecting transducer beams 614, 616. Specifically, the fifth transducer beam 614 is connected to an inner side of the fourth transducer beam 612 on one of its longitudinal ends, and the side portion 602b of the central body portion 602 on the other one of its longitudinal ends, and the fifth transducer beam 614 is disposed generally perpendicular to the side portion 602b of the central body portion 602 and to fourth transducer beam 612. Similarly, the sixth transducer beam 616 is connected to the inner side of the fourth transducer beam 612 on one of its longitudinal ends, and the side portion 602b of the central body portion 602 on the other one of its longitudinal ends, and the sixth transducer beam 616 is disposed generally perpendicular to the side portion 602b of the central body portion 602 and to fourth transducer beam 612. Also, as shown in FIG. 22, it can be seen that the bottom surface of the first transducer beam 606 and the bottom surface of the fourth transducer beam 612 each comprises a central standoff portion 620. In addition, it can be seen that the opposed longitudinal ends of the first transducer beam 606 and the fourth transducer beam 612 are each provided with raised standoff portions 618. Each raised standoff portion 618 is provided with a mounting aperture 622 disposed therethrough for accommodating a respective fastener (e.g., a screw) that attaches the load transducer 600 to another object, such as a robotic arm, etc.
As best shown in the perspective view of FIG. 22, the illustrated load cells are located on the transducer beams 606, 608, 610, 612, 614, 616. In the illustrated embodiment, each load cell comprises one or more strain gages 624, 626, 628. Specifically, in the illustrated embodiment, the first transducer beam 606 and the fourth transducer beam 612 each comprise a pair of spaced apart strain gages 624 disposed on the top surfaces thereof that are sensitive to the vertical force component (i.e., FZ strain gages). In FIG. 22, it can be seen that each of the strain gages 624 is disposed near the raised standoff portions 618 at the opposed ends of the beams 606, 612. Also, in the illustrated embodiment, the second transducer beam 608, the third transducer beam 610, the fifth transducer beam 614, and the sixth transducer beam 616 each comprise a strain gage 626 disposed on an outer side surface thereof that is sensitive to a first shear force component (i.e., a FX strain gage). The first transducer beam 606 and the fourth transducer beam 612 also each comprise a plurality of spaced apart strain gages 628 (e.g., two spaced apart strain gages 628) disposed on an outer side surface thereof that is sensitive to a second shear force component (i.e., a FY strain gage).
FIG. 23 illustrates a load transducer 700 according to a ninth exemplary embodiment of the present invention. With reference to this figure, it can be seen that, in some respects, the ninth exemplary embodiment is similar to that of the eighth embodiment. Moreover, some parts are common to all of the embodiments. For the sake of brevity, the parts that the ninth embodiment of the load transducer has in common with the eighth embodiment will only be briefly mentioned because these components have already been explained in detail above.
Initially, referring to the perspective view of FIG. 23, it can be seen that, like the eighth embodiment described above, the load transducer 700 generally includes a one-piece compact transducer frame 704 with a central body portion 702 and a plurality of transducer beams 706, 708, 710, 712, 714, 716 connected thereto. Although, each of connecting transducer beams 708, 710, and each of connecting transducer beams 714, 716, are spaced considerably further apart from one another as compared to the connecting transducer beams 608, 610, 614, 616 of the load transducer 600 such that the connecting beams 708, 710, 714, 716 are generally axially aligned with the side portions 702a, 702c of the central body portion 702.
With reference again to FIG. 23, it can be seen that the illustrated central body portion 702 is generally in the form of square band-shaped element with a central opening 730 disposed therethrough. In FIG. 23, it can be seen that the body portion 702 comprises a first pair of opposed side portions 702a, 702c and a second pair of opposed side portions 702b, 702d. The side portion 702a is disposed generally parallel to the side portion 702c, while the side portion 702b is disposed generally parallel to the side portion 702d. Each of the side surfaces of the side portions 702a, 702b, 702c, 702d is disposed generally perpendicular to the planar top and bottom surfaces thereof. Also, each of the first pair of opposed side portions 702a, 702c is disposed generally perpendicular to each of the second pair of opposed sides portions 702b, 702d. In addition, as shown in FIG. 23, each of the opposed side portions 702b, 702d is connected to a respective set of transducer beams 706, 708, 710 and 712, 714, 716. In the illustrated embodiment, it can be seen that each of the opposed side portions 702a, 702c comprises a plurality of apertures 732 (e.g., two apertures 732) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 700 to another object, such as a robotic arm, etc. Also, as depicted in the FIG. 23, the central body portion 702 comprises a raised bottom portion or bottom standoff portion 720 for spacing the transducer beams 706, 708, 710, 712, 714, 716 apart from an object (e.g., robotic arm) to which the load transducer 700 is attached so that forces and/or moments are capable of being accurately measured by the load transducer 700.
As shown in FIG. 23, the first set of illustrated transducer beams 706, 708, 710 of the transducer frame 704 is arranged in a generally T-shaped configuration on a first side of the central body portion 702 (with the wide base of the T-shaped arrangement being formed by the connecting beam transducers 708, 710). A first side aperture 734 is formed between the side portion 702d of the central body portion 702 and the first set of transducer beam side portions 706, 708, 710. Referring again to FIG. 23, it can be seen that the first transducer beam 706 is connected to the side portion 702d of the central body portion 702 by means of two spaced apart connecting transducer beams 708, 710. Specifically, the second transducer beam 708 is connected to an inner side of the first transducer beam 706 on one of its longitudinal ends, and the side portion 702d of the central body portion 702 on the other one of its longitudinal ends, and the second transducer beam 708 is disposed generally perpendicular to the side portion 702d of the central body portion 702 and to first transducer beam 706. Similarly, the third transducer beam 710 is connected to the inner side of the first transducer beam 706 on one of its longitudinal ends, and the side portion 702d of the central body portion 702 on the other one of its longitudinal ends, and the third transducer beam 710 is disposed generally perpendicular to the side portion 702d of the central body portion 702 and to first transducer beam 706. Turning again to FIG. 23, it can be seen that the second set of transducer beams 712, 714, 716 of the transducer frame 704 is arranged in a generally T-shaped configuration on a second side of the central body portion 702, which is opposite to the first side of the central body portion 702 (with the wide base of the T-shaped arrangement being formed by the connecting beam transducers 714, 716). A second side aperture 734 is formed between the side portion 702b of the central body portion 702 and the second set of transducer beam side portions 712, 714, 716. In FIG. 23, similar to the first transducer beam 706, it can be seen that the fourth transducer beam 712 is connected to the side portion 702b of the central body portion 702 by means of two spaced apart connecting transducer beams 714, 716. Specifically, the fifth transducer beam 714 is connected to an inner side of the fourth transducer beam 712 on one of its longitudinal ends, and the side portion 702b of the central body portion 702 on the other one of its longitudinal ends, and the fifth transducer beam 714 is disposed generally perpendicular to the side portion 702b of the central body portion 702 and to fourth transducer beam 712. Similarly, the sixth transducer beam 716 is connected to the inner side of the fourth transducer beam 712 on one of its longitudinal ends, and the side portion 702b of the central body portion 702 on the other one of its longitudinal ends, and the sixth transducer beam 716 is disposed generally perpendicular to the side portion 702b of the central body portion 702 and to fourth transducer beam 712. Also, in FIG. 23, it can be seen that the opposed longitudinal ends of the first transducer beam 706 and the fourth transducer beam 712 are each provided with raised standoff portions 718. Each raised standoff portion 718 is provided with a mounting aperture 722 disposed therethrough for accommodating a respective fastener (e.g., a screw) that attaches the load transducer 700 to another object, such as a robotic arm, etc.
As best shown in the perspective view of FIG. 23, the illustrated load cells are located on the transducer beams 706, 708, 710, 712, 714, 716. In the illustrated embodiment, each load cell comprises one or more strain gages 724, 726, 728. Specifically, in the illustrated embodiment, the first transducer beam 706 and the fourth transducer beam 712 each comprise a pair of spaced apart strain gages 724 disposed on the top surfaces thereof that are sensitive to the vertical force component (i.e., FZ strain gages). In FIG. 23, it can be seen that each of the strain gages 724 is disposed near the raised standoff portions 718 at the opposed ends of the beams 706, 712. Also, in the illustrated embodiment, the second transducer beam 708, the third transducer beam 710, the fifth transducer beam 714, and the sixth transducer beam 716 each comprise a strain gage 726 disposed on an outer side surface thereof that is sensitive to a first shear force component (i.e., a FX strain gage). The first transducer beam 706 and the fourth transducer beam 712 also each comprise a plurality of spaced apart strain gages 728 (e.g., two spaced apart strain gages 728) disposed on an outer side surface thereof that is sensitive to a second shear force component (i.e., a FY strain gage).
FIG. 24 illustrates a load transducer 800 according to a tenth exemplary embodiment of the present invention. With reference to this figure, it can be seen that, in some respects, the tenth exemplary embodiment is similar to that of the preceding embodiments. Moreover, some parts are common to all of the embodiments. For the sake of brevity, the parts that the tenth embodiment of the load transducer has in common with the preceding embodiments will only be briefly mentioned because these components have already been explained in detail above.
Initially, referring to the perspective view of FIG. 24, it can be seen that the load transducer 800 generally includes a one-piece compact transducer frame 804 with a central body portion 802 and a plurality of L-shaped transducer beams 806, 808, 810, 812 connected thereto. As shown in FIG. 24, each of the L-shaped transducer beams 806, 808, 810, 812 is generally disposed at a respective corner of the central body portion 802.
With reference again to FIG. 24, it can be seen that the illustrated central body portion 802 is generally in the form of square band-shaped element with a central opening 826 disposed therethrough. In FIG. 24, it can be seen that the body portion 802 comprises a first pair of opposed side portions 802a, 802c and a second pair of opposed side portions 802b, 802d. The side portion 802a is disposed generally parallel to the side portion 802c, while the side portion 802b is disposed generally parallel to the side portion 802d. Each of the side surfaces of the side portions 802a, 802b, 802c, 802d is disposed generally perpendicular to the planar top and bottom surfaces thereof. Also, each of the first pair of opposed side portions 802a, 802c is disposed generally perpendicular to each of the second pair of opposed sides portions 802b, 802d. In addition, as shown in FIG. 24, each of the corners of the central body portion 802 is connected to a respective L-shaped transducer beam 806, 808, 810, 812. In the illustrated embodiment, it can be seen that each of the opposed side portions 802a, 802c comprises a plurality of apertures 828 (e.g., two apertures 828) disposed therethrough for accommodating fasteners (e.g., screws) that attach the load transducer 800 to another object, such as a robotic arm, etc. Also, as depicted in the FIG. 24, the central body portion 802 comprises a raised bottom portion or bottom standoff portion 816 for spacing the L-shaped transducer beams 806, 808, 810, 812 apart from an object (e.g., robotic arm) to which the load transducer 800 is attached so that forces and/or moments are capable of being accurately measured by the load transducer 800.
As shown in FIG. 24, the first generally L-shaped transducer beam 806 comprises a first beam portion 806a and a second beam portion 806b, wherein the first beam portion 806a is disposed generally perpendicular to the second beam portion 806b. Similarly, the second generally L-shaped transducer beam 808 comprises a first beam portion 808a and a second beam portion 808b, wherein the first beam portion 808a is disposed generally perpendicular to the second beam portion 808b. Also, it can be seen in FIG. 24 that the first beam portion 806a of the first generally L-shaped transducer beam 806 and the first beam portion 808a of the second generally L-shaped transducer beam 808 are both generally axially aligned with the side portion 802a of the central body portion 802 (i.e., the longitudinal axes of the beam portions 806a, 808a are generally aligned with the longitudinal axis of the side portion 802a). With reference again to FIG. 24, the third generally L-shaped transducer beam 810 comprises a first beam portion 810a and a second beam portion 810b, wherein the first beam portion 810a is disposed generally perpendicular to the second beam portion 810b. Similarly, the fourth generally L-shaped transducer beam 812 comprises a first beam portion 812a and a second beam portion 812b, wherein the first beam portion 812a is disposed generally perpendicular to the second beam portion 812b. Also, it can be seen in FIG. 24 that the first beam portion 810a of the third generally L-shaped transducer beam 810 and the first beam portion 812a of the fourth generally L-shaped transducer beam 812 are both generally axially aligned with the side portion 802c of the central body portion 802 (i.e., the longitudinal axes of the beam portions 810a, 812a are generally aligned with the longitudinal axis of the side portion 802c). Also, in FIG. 24, it can be seen that the free ends of the second beam portions 806b, 808b, 810b, 812b of the L-shaped transducer beams 806, 808, 810, 812 are each provided with raised standoff portions 814. Each raised standoff portion 814 is provided with a mounting aperture 818 disposed therethrough for accommodating a respective fastener (e.g., a screw) that attaches the load transducer 800 to another object, such as a robotic arm, etc.
As best shown in the perspective view of FIG. 24, the illustrated load cells are located on the L-shaped transducer beams 806, 808, 810, 812. In the illustrated embodiment, each load cell comprises one or more strain gages 820, 822, 824. Specifically, in the illustrated embodiment, the second beam portions 806b, 808b, 810b, 812b of the L-shaped transducer beams 806, 808, 810, 812 are each provided with a strain gage 820 disposed on the top surface thereof that is sensitive to the vertical force component (i.e., an FZ strain gage). In FIG. 24, it can be seen that each of the strain gages 820 is disposed near the raised standoff portions 818 of the second beam portions 806b, 808b, 810b, 812b. Also, in the illustrated embodiment, the second beam portions 806b, 808b, 810b, 812b of the L-shaped transducer beams 806, 808, 810, 812 each comprise a strain gage 822 disposed on an outer side surface thereof that is sensitive to a first shear force component (i.e., a FX strain gage). The first beam portions 806a, 808a, 810a, 812a of the L-shaped transducer beams 806, 808, 810, 812 each comprise a strain gage 824 disposed on an outer side surface thereof that is sensitive to a second shear force component (i.e., a FY strain gage).
In the illustrated embodiments of the present invention, the transducer beams do not extend from a top or upper surface of the central body portion. As such, there is no gap formed between the top or upper surface of the central body portion and a bottom or lower surface of one or more of the transducer beams. Rather, in the exemplary embodiments comprising a central body portion, the transducer beams extend outwardly from a side or lateral surface of the central body portion so as to minimize the overall height of the transducer profile (i.e., because the transducer beams are not required to be disposed above the central body portion). Also, in the illustrated embodiments discussed above, the transducer beams are not in the form of generally linear beams, and are not in the form of generally linear beams with generally symmetrical end portions. Rather, the transducer beams of the exemplary embodiments generally either emanate from a central body portion and have only one cantilevered end or are arranged in a continuous band-like configuration. In addition, it can be seen that, except for the top and bottom standoff portions on either the transducer beams or the central body portions, the top and bottom surfaces of the transducer beams of the exemplary embodiments are generally co-planar with the respective top and bottom surfaces of the central body portion. Similarly, in the exemplary embodiments having a band-like configuration of transducer beams, the top surfaces of each of the looped transducer beams are generally co-planar with one another, while the bottom surfaces of each of the looped transducer beams are also generally co-planar with one another.
Any of the features or attributes of the above described embodiments and variations can be used in combination with any of the other features and attributes of the above described embodiments and variations as desired.
It is apparent from the above detailed description that the present invention provides a low profile six-component load transducer 10, 10′, 100, 200, 300, 400, 500, 600, 700, 800 which has a significant allowable offset for the line of action of the force. In that, for a given allowable maximum load, this load transducer has a much higher moment capacity than currently available load transducers and the offset value can be as high as five times the diameter (or width dimension) of the transducer. Therefore, the load transducer 10, 10′, 100, 200, 300, 400, 500, 600, 700, 800 according to the present invention is able to withstand and measure moments which are approximately ten times higher than that of a similarly sized and rated conventional load cell.
From the foregoing disclosure and detailed description of certain preferred embodiments, it is also apparent that various modifications, additions and other alternative embodiments are possible without departing from the true scope and spirit of the present invention. The embodiments discussed were chosen and described to provide the best illustration of the principles of the present invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present invention as determined by the appended claims when interpreted in accordance with the benefit to which they are fairly, legally, and equitably entitled.

## Claims

1. A load transducer comprising, in combination:
a central body portion having a plurality of sides;
a plurality of beams extending outwardly from the sides of the central body portion, each of the plurality of beams being supported in a cantilevered manner from the central body portion, one or more of the plurality of beams comprising a first top surface that is disposed at a first elevation relative to a bottom surface of the central body portion and a second top surface that is disposed at a second elevation relative to the bottom surface of the central body portion, the second elevation being greater than the first elevation, and wherein a recessed area created by the difference in elevation between the second elevation and the first elevation is used to accommodate one or more load cell electrical components; and
a plurality of load cells, each of the load cells being disposed on one of the beams, the plurality of load cells configured to measure one or more force components or one or more moment components, or both one or more force components and one or more moment components.

2. The load transducer according to claim 1, wherein one or more of the plurality of load cells comprises a strain gage configured to measure a load component applied at a respective one of the end portions of the beams.

3. The load transducer according to claim 1, wherein the central body portion and the plurality of beams are each part of a transducer frame, the transducer frame being compact and of one-piece construction.

4. The load transducer according to claim 1, wherein the plurality of beams comprises at least six beams, and wherein the plurality of load cells comprises at least three load cells that are configured to be sensitive to a vertical force component, at least two load cells that are configured to be sensitive to a first shear force component, and at least two load cells that are configured to be sensitive to a second shear force component, the first shear force component being generally perpendicular to the second shear force component, and each of the first and second shear force components being generally perpendicular to the vertical force component.

5. The load transducer according to claim 1, wherein the plurality of beams comprises at least two pairs of beams that are disposed generally parallel to one another.

6. The load transducer according to claim 5, wherein each of the at least two pairs of beams comprises two beams that are laterally spaced apart from one another by a gap.

7. The load transducer according to claim 1, wherein the plurality of beams comprises at least two generally U-shaped beams that are disposed diagonally opposite to one another across the central body portion.

8. The load transducer according to claim 1, wherein the plurality of beams comprises a first set of beams disposed on a first side of the central body portion and a second set of beams disposed on a second side of the central body portion, the first side of the central body portion being opposite to the second side of the central body portion, each of the first and second sets of beams comprising an arrangement of beams disposed in a generally C-shaped configuration, the first set of beams forming a closed loop together with the first side of the central body portion, and the second set of beams forming a closed loop together with the second side of the central body portion.

9. The load transducer according to claim 1, wherein the plurality of beams comprises a first set of beams disposed on a first side of the central body portion and a second set of beams disposed on a second side of the central body portion, the first side of the central body portion being opposite to the second side of the central body portion, each of the first and second sets of beams comprising an arrangement of beams disposed in a generally T-shaped configuration with a base of the generally T-shaped configuration being formed by two spaced apart beams.

10. The load transducer according to claim 1, wherein the plurality of beams comprises at least two generally L-shaped beams that are disposed diagonally opposite to one another across the central body portion.

11. The load transducer according to claim 1, wherein the plurality of sides of the central body portion comprise a first side, a second side disposed generally opposite to the first side, a third side, and a fourth side disposed generally opposite to the third side; and
wherein at least a first of the plurality of beams extends outwardly from the first side of the central body portion, at least a second of the plurality of beams extends outwardly from the second side of the central body portion, at least a third of the plurality of beams extends outwardly from the third side of the central body portion, and at least a fourth of the plurality of beams extends outwardly from the fourth side of the central body portion.

12. A load transducer comprising, in combination:
a central body portion having a plurality of sides;
a plurality of beams extending outwardly from the sides of the central body portion, each of the plurality of beams including an end portion that is supported in a cantilevered manner from the central body portion, one or more of the plurality of beams comprising a first top surface that is disposed at a first elevation relative to a bottom surface of the central body portion and a second top surface that is disposed at a second elevation relative to the bottom surface of the central body portion, the second elevation being greater than the first elevation, and wherein a recessed area created by the difference in elevation between the second elevation and the first elevation is used to accommodate one or more load cell electrical components; and
a plurality of load cells, each of the load cells being disposed on one of the beams, the plurality of load cells including at least three load cells that are configured to be sensitive to a vertical force component, at least two load cells that are configured to be sensitive to a first shear force component, and at least two load cells that are configured to be sensitive to a second shear force component, the first shear force component being generally perpendicular to the second shear force component, and each of the first and second shear force components being generally perpendicular to the vertical force component.

13. The load transducer according to claim 12, wherein one or more of the plurality of load cells comprises a strain gage configured to measure a load component applied at a respective one of the end portions of the beams.

14. The load transducer according to claim 12, wherein the central body portion and the plurality of beams are each part of a transducer frame, the transducer frame being compact and of one-piece construction.

15. The load transducer according to claim 12, wherein the plurality of sides of the central body portion comprise a first side, a second side disposed generally opposite to the first side, a third side, and a fourth side disposed generally opposite to the third side; and
wherein at least a first of the plurality of beams extends outwardly from the first side of the central body portion, at least a second of the plurality of beams extends outwardly from the second side of the central body portion, at least a third of the plurality of beams extends outwardly from the third side of the central body portion, and at least a fourth of the plurality of beams extends outwardly from the fourth side of the central body portion.

16. The load transducer according to claim 12, wherein one or more of the plurality of beams comprises a mounting aperture disposed near a respective end thereof for accommodating a fastener.

17. The load transducer according to claim 12, wherein the plurality of beams comprises at least two generally U-shaped beams that are disposed diagonally opposite to one another across the central body portion.

18. A load transducer comprising, in combination:
a plurality of beams arranged in a band-shaped configuration forming a closed loop, at least one of the plurality of beams being disposed generally perpendicular to at least another one of the plurality of beams, one or more of the plurality of beams having a first top surface, a second top surface, and a bottom surface, the first top surface of the one or more of the plurality of beams being disposed at a first elevation relative to the bottom surface of the one or more of the plurality of beams, and the second top surface of the one or more of the plurality of beams being disposed at a second elevation relative to the bottom surface of the one or more of the plurality of beams, the second elevation being greater than the first elevation, and wherein a recessed area created by the difference in elevation between the second elevation and the first elevation is used to accommodate one or more load cell electrical components; and
a plurality of load cells, each of the load cells being disposed on one of the beams, the plurality of load cells configured to measure one or more force components or one or more moment components, or both one or more force components and one or more moment components.

19. The load transducer according to claim 18, further comprising a central body portion that is at least partially circumscribed by the plurality of beams arranged in the band-shaped configuration.

20. The load transducer according to claim 19, wherein at least one of the plurality of beams arranged in the band-shaped configuration is spaced apart from a lateral side of the central body portion by a gap.