Patent Publication Number: US-2013239701-A1

Title: Multi-axis loadcell

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of transducer technology, and more particularly, to a multi-axis loadcell. 
     BACKGROUND OF THE INVENTION 
     Multi-axis loadcells are widely used in the field of Aeronautics and Astronautics, automotive, robotics, automation, medical and sports equipment, e.g. the six component balance in the wind tunnel test, the six-DOF wheel force sensor in the vehicle road test, the multi-axis loadcell for Crash Test Dummy in the auto crash test, etc. 
     According to the different decoupling method, the multi-axis loadcells could be classified into two types: structurally decoupled multi-axis loadcell and algorithm decoupled multi-axis loadcell. The key point of the multi-axis loadcell lies in the flexure design, the placement and the bridge circuit of the strain gages. The structurally decoupled design allows the removal of the coupling between axes due to the specific flexure design and strain gage placement so that the output signals of the loadcell are the actual forces and moments. In the algorithm decoupled design, the actual forces and moments are obtained by manipulating the output signals through a specific algorithm, due to the coupling between each axis is significant. Regardless the six axis loadcell is structurally decoupled or algorithm decoupled, overload protection is always required for industrial robot application in the complex and demanding operation environment. 
     SUMMARY OF THE INVENTION 
     One objective of the present invention is to provide a multi-axis loadcell which allows for convenient installment, and is characteristic of simple construction. 
     To achieve the above-mentioned object, the present invention provides a multi-axis loadcell, which includes a flexure; wherein the flexure includes a upper member, a lower member and at least three force-measuring beams; each of the force-measuring beams having a rectangle-shaped cross section and being arranged between the upper member and the lower member with its upper end connected to the upper member and its lower end connected to the lower member; the force-measuring beam including a front side, a rear side opposite to the front side, a left side and a right side opposite to the left side; the multi-axis loadcell further comprising at least four strain gages, each of which is arranged on a surface of the side of the force-measuring beam for measuring longitudinal strain, transverse strain, shearing strains of positive 45° and negative 45° simultaneously; wherein at least two strain gages being respectively arranged in middle of a same side surface of the force-measuring beam in the longitudinal and transverse directions for measuring longitudinal strain and transverse strain; while at least two strain gages being respectively arranged in middle of a same side surface of the force-measuring beam in the positive 45° direction and negative 45° direction, for measuring the shearing strains of positive 45° and of negative 45°. 
     As an embodiment of the present invention, at least four strain gages are arranged in the middle of one side of the force-measuring beam in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, configured to measure the longitudinal strain, the transverse strain, and the shearing strain of positive 45° and of negative 45° respectively. 
     As another embodiment of the present invention, plurality of top supports extend from the lower end of the upper member, while a plurality of bottom supports extend from the upper end of the lower member; the top support is engaged with the bottom support correspondingly to form a junction with a gap form therein; when the gap is decreased, which is caused by a relative replacement between the top support and the bottom support, the top support is contacted with the bottom support to form a mutual limitation for each other; wherein both of the number of the top support and the number of the bottom support are larger than or equal to three. 
     The multi-axis loadcell according to the embodiment of the present invention includes a flexure and a plurality of strain gages which are used to measure the longitudinal strain, the transverse strain, and the shearing strains of positive 45° and of negative 45° negative simultaneously. While forces or moments are applied to the multi-axis loadcell, the force-measuring beams produce strain, and the strain is measured and converted into output electrical signal by strain gages. In comparison with the prior art, this multi-axis loadcell allows for convenient installment, and is characteristic of simple construction, could achieve not only structure decoupling but also algorithm decoupling, and enables to measure the force signal value and torque signal value which are applied onto the transducer. Furthermore, there are top supports and bottom supports which are used as an overload protection structure on the multi-axis loadcell. The loadcell is prevented from being damaged in the complex and demanding operation environment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other aspects, features, and advantages of this invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of this invention. The accompanying drawings facilitate an understanding of the various embodiments of this invention. In such drawings: 
         FIG. 1  is a schematic illustration of multi-axis loadcell without any plate according to the embodiment of the present invention; 
         FIG. 2  is a schematic illustration of multi-axis loadcell with plates according to the embodiment of the present invention; 
         FIG. 3  is an elevation drawing illustrating the multi-axis loadcell according to the embodiment of the present invention; 
         FIG. 4  is a partial enlarged drawing illustrating a force-measuring beam of the multi-axis loadcell shown in  FIG. 3  according to the embodiment of the present invention; 
         FIG. 5  is a schematic illustration of the multi-axis loadcell according to the first embodiment of the present invention; 
         FIG. 6  is a schematic illustration of the bridges connection of the strain gage of the multi-axis loadcell according to the first embodiment of the present invention; 
         FIG. 7  is a schematic illustration of the multi-axis loadcell according the second embodiment of the present invention; 
         FIG. 8  is a schematic illustration of the multi-axis loadcell according the third embodiment of the present invention; 
         FIG. 9  is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the third embodiment of the present invention; 
         FIG. 10  is a schematic illustration of the multi-axis loadcell according the fourth embodiment of the present invention; 
         FIG. 11  is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the fourth embodiment of the present invention; 
         FIG. 12  is a schematic illustration of the multi-axis loadcell according the fifth embodiment of the present invention; 
         FIG. 13  is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the fifth embodiment of the present invention; 
         FIG. 14  is a schematic illustration of the multi-axis loadcell according the sixth embodiment of the present invention; 
         FIG. 15  is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the sixth embodiment of the present invention; 
         FIG. 16  is a schematic illustration of the multi-axis loadcell according the seventh embodiment of the present invention; 
         FIG. 17  is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the seventh embodiment of the present invention; 
         FIG. 18  is a schematic illustration of the multi-axis loadcell according the eighth embodiment of the present invention; and 
         FIG. 19  is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the eighth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS 
     Various preferred embodiments of the invention will now be described with reference to the figures, obviously, the described embodiment hereinafter is parts of the embodiments of the present invention, not all the embodiment. Based on the embodiment of the present invention, other embodiments obtained without any creative word by the ordinary in the art is within the protection scope of the present invention. 
     The multi-axis loadcell according to the embodiments of the present invention includes a flexure; the flexure comprising a upper member, a lower member and at least three force-measuring beams; the force-measuring beam having a rectangle-shape cross section; the force-measuring beams being arranged between the upper member and the lower member; an upper end of the force-measuring beam being connected to the upper member, an lower end of the force-measuring beam being connected to the lower member; the force-measuring beam including a front side, a rear side, a left side and a right side, with the front side being opposite to the rear side, and the left side being opposite to the right side; the multi-axis loadcell further having at least four strain gages, the strain gages being arranged on the surface of the side of the force-measuring beam, configured to measure longitudinal strain, transverse strain, shearing strain of positive 45° and shearing strain of negative 45° simultaneously; at least two strain gages being arranged in the middle of the same side of the force-measuring beam in the longitudinal and transverse directions respectively, configured to measure the longitudinal strain and the transverse strain; at least two strain gages being arranged in the middle of the same side of the force-measuring beam in the positive 45° and negative 45° directions respectively, configured to measure the shearing strain of positive 45° and of negative 45°. The bridge circuit employs full bridge or half bridge. 
     Within a preferable embodiment of the present invention, at least four strain gages are arranged in the middle of the same side of the force-measuring beam in the directions of longitudinal, transverse, positive 45° and negative 45°, configured to measure the longitudinal strain, the transverse strain, and the shearing strains of positive 45° and of negative 45°. 
     The term “positive 45° ” is at positive 45° compared to the transverse direction, “negative 45° ” is at negative 45° compared to the transverse direction. 
     Referring to  FIG. 1 , it shows a schematic illustration of multi-axis loadcell without any plate according to the embodiment of the present invention. 
     As shown in  FIG. 1 , the flexure  1  of the multi-axis loadcell includes an upper member  2 , a lower member  3  and at least three force-measuring beams  4 . The upper member  2  are coupled to the lower member  3  via the force-measuring beams  4 , that is, the force-measuring beams  4  are arranged between the upper member  2  and the lower member  3 , the top of the force-measuring beam  4  is connected to the upper member  2 , and the bottom of the force-measuring beam  4  is connected to the lower member  3 . 
     A plurality of top supports  5  extend from the lower end of the upper member  2 , while a plurality of bottom supports  6  extend from the upper end of the lower member  3 ; the top support  5  is engaged with the bottom support  6  correspondingly to form a junction with a gap  7  form therein; when the gap  7  is decreased, which is caused by a relative replacement between the top support  5  and the bottom support  6 , the top support  5  is contacted with the bottom support  6  to form a mutual limitation for each other; wherein both of the number of the top support  5  and the number of the bottom support  6  are larger than or equal to three. 
     In an embodiment of the present invention, no plate is inserted into the gap  7  of the junction formed by the top support  5  and the bottom support  6 .  FIG. 1  shows a schematic illustration of multi-axis loadcell without any plate. 
     In another embodiment, referring to  FIG. 2 , it is a schematic illustration of multi-axis loadcell with plates. A plate  10  is inserted into the gap  7  of the junction formed by the top support  5  and the bottom support  6 . 
     Referring to  FIG. 3 , it is an elevation drawing illustrating the multi-axis loadcell according to the embodiment of the present invention. 
     As shown in  FIG. 3 , a groove  8  is formed in the upper member  2  above the junction of the force-measuring beam  4  and the upper member  2 ; a groove  9  is formed in the lower member  3  below the junction of the force-measuring beam  4  and the lower member  3 . 
       FIG. 4  is a partial enlarged drawing illustrating a force-measuring beam of the multi-axis loadcell shown in  FIG. 3 . 
     At least one strain gage is arranged on the side surface (position I as shown in  FIG. 3 ) of the force-measuring beam  4 . For example, as shown in  FIG. 4 , a strain rosette  11  is arranged onto the side surface of the force-measuring beam  4 . The resistance strain rosette is a kind of strain gage having two or more sensitive grids. In practice, the strain rosette  11  could be replaced by several strain gages Rn. 
     The flexure  1  of the multi-axis loadcell according to the present invention has top supports  5  and bottom supports  6  which are engaged with each other correspondingly to form junctions therebetween, and gap  7  is form at the junction, which serves the function that: when the multi-axis loadcell is applied on force or moment, a relative replacement exists between the upper member  2  and the lower member  3  of the flexure  1 , the gap  7  between the top support  5  the bottom support  6  is getting smaller. When the force or moment is beyond a predetermined value, the gap  7  between the top support  5  and the bottom support  6  is disappeared, and then the top support  5  and the bottom support  6  are contacted with each other, serving the function of overload protection, so that the strain gage of the force-measuring beam  4  is prevented from being damaged. 
     According to multi-axis loadcell, the groove  8  is formed in the upper member  2 , and a groove  9  is formed in the lower member  3 , which serves the function that: forming grooves on the upper member  2  and the lower member  3  is to reducing stiffness thereof. When the force or moment is overloaded, the groove  8  and the groove  9  facility a bigger relative displacement between the upper member  2  and the lower member  3 , and ensure the top support  5  and the bottom support  6  to contacted with each other, so that the strain gage of the force-measuring beam  4  is prevented from being damaged. 
     Preferably, referring to  FIG. 2 , the upper member  2  and the lower member  3  are both circular. At least three force-measuring beams  4  are arranged on the outskirts of the upper member  2  and the lower member  3 , to couple the upper member  2  to the lower member  3 . In the embodiment, the force-measuring beams  4  could be evenly distributed, and it also could not be without evenly distributed. 
     Preferably, the force-measuring beam  4  could be rectangle shape, and the force-measuring beam  4  includes a front side, a rear side, a left side and a right side; wherein, the front side is facing outwards regarding to the force-measuring beam, the rear side is facing the centerline of the force-measuring beam, and the left side and the right side are the two side of the force-measuring beam. The front side is opposite to the rear side, and the left side is opposite to the right side. 
     It should be noted that, the embodiments of the present invention are merely described by the shape of annular, the upper member  2  and the lower member  3  could be any other shape, e.g. the upper member  2  and the lower member  3  also could be rectangle shape, hexagon shape or octahedron shape, etc. the structure of the upper member  2  could be identical with that of the lower member  3 , also could be different from that of the lower member  3 , both of them could be parallel to each other; there could be holes formed in the upper member  2  and the lower member  3 . 
     The top support, the bottom support, the plate and the grooves formed in the top support and the bottom support are used for overload protection, whose shapes are without specific shapes. As long as the top supports are engaged with the bottom supports correspondingly and they could be limited to each other, the over load protection can be achieved. If the overload protection function is not necessary in practice, the multi-axis loadcell could be set without any overload protection structure. 
     This multi-axis loadcell allows for convenient installment, and is characteristic of simple construction, could achieve not only structure decoupling but also algorithm decoupling. Furthermore, the multi-axis loadcell could serve the function of overload protection, and avoid damaging the transducer, so as to adjust to the extreme and complicated operation demand. Combined with  FIGS. 5-19 , the following statement is detailedly described with the arrangement and the bridge circuit method of the strain gage of the multi-axis loadcell. 
     Referring to  FIG. 5 , it is a schematic illustration of the multi-axis loadcell according to the first embodiment of the present invention. 
     In the first embodiment, four strain gages are arranged on one side of the force-measuring beam in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, configured to measure the longitudinal strain, the transverse strain, and the shearing strains of positive 45° and of negative 45° respectively. 
     As shown in  FIG. 5 , the multi-axis loadcell includes three force-measuring beams, which are force-measuring beam  4   a , force-measuring beam  4   b  and force-measuring beam  4   c . Four strain gages are arranged on each of the above force-measuring beams, the detailed is as follow: 
     Four strain gages are arranged on front side of force-measuring beam  4   a  in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 11 , R 13 , R 14  and R 12  as shown in  FIG. 5 ; 
     Four strain gages are arranged on front side of force-measuring beam  4   b  in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 21 , R 23 , R 24  and R 22  as shown in  FIG. 5 ; 
     Four strain gages are arranged on front side of force-measuring beam  4   c  in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 31 , R 33 , R 34  and R 32  as shown in  FIG. 5 ; 
     In practice, four strain gages arranged on the same side of the force-measuring beam in the directions of longitudinal, transverse, positive 45° and negative 45° respectively could be stacked together or not stacked. The above four strain gages could be replaced by strain rosette. 
     Referring to  FIG. 6 , it is a schematic illustration of the bridges connection of the strain gage of the multi-axis loadcell according to the first embodiment of the present invention. 
     According to the multi-axis loadcell of the first embodiment, resistances Ra and Rb are employed in bridges circuit design of the strain gage, and the resistance values of resistances Ra and Rb are not changed when the force-measuring beam is applied on force. Referring to  FIG. 6 , there are six signal channels to output signal according to the bridges circuit design of the strain gage, which are signals CH 1 , CH 2 , CH 3 , CH 4 , CH 5  and CH 6 . The detailed is as follow: 
     R 11 , R 13 , Ra and Rb constitute a bridge circuit as shown in  FIG. 6 , when the flexure is applied on force to produce strain, the resistance changes of R 11  and R 13  are ΔR 11  and ΔR 13 , the strain is converted into electrical signal, to obtain signal CH 1 . 
     R 12 , R 14 , Ra and Rb constitute a bridge circuit as shown in  FIG. 6 , when the flexure is applied on force to produce strain, the resistance changes of R 12  and R 14  are ΔR 12  and ΔR 14 , the strain is converted into electrical signal, to obtain signal CH 2 . 
     R 31 , R 33 , Ra and Rb constitute a bridge circuit as shown in  FIG. 6 , when the flexure is applied on force to produce strain, the resistance changes of R 31  and R 33  are ΔR 31  and ΔR 33 , the strain is converted into electrical signal, to obtain signal CH 3 . 
     R 32 , R 34 , Ra and Rb constitute a bridge circuit as shown in  FIG. 6 , when the flexure is applied on force to produce strain, the resistance changes of R 32  and R 34  are ΔR 32  and ΔR 34 , the strain is converted into electrical signal, to obtain signal CH 4 . 
     R 21 , R 23 , Ra and Rb constitute a bridge circuit as shown in  FIG. 6 , when the flexure is applied on force to produce strain, the resistance changes of R 21  and R 23  are ΔR 21  and ΔR 23 , the strain is converted into electrical signal, to obtain signal CH 5 . 
     R 22 , R 24 , Ra and Rb constitute a bridge circuit as shown in  FIG. 6 , when the flexure is applied on force to produce strain, the resistance changes of R 22  and R 24  are ΔR 22  and ΔR 24 , the strain is converted into electrical signal, to obtain signal CH 6 . 
     After signals CH 1 , CH 2 , CH 3 , CH 4 , CH 5  and CH 6  output from six channels of the multi-axis loadcell are obtained, they are decoupled via matrix computation, then the value of the force or force torque signals which are applied onto the transducer are obtained. This decoupling is carried out by the following matrix computation in this embodiment: [F]=[C][CH]; matrix[F] includes force signals FX, FY, FZ and force torque signals MX, MY and MZ; wherein, signal FX is the force signal along the X-axis direction as shown in  FIG. 5 , signal FY is the force signal along the Y-axis direction as shown in  FIG. 5 , signal FZ is the force signal along the Z-axis direction as shown in  FIG. 5 . Signal MX is the force torque signal along the X-axis direction as shown in  FIG. 5 , signal MY is the force torque signal along the Y-axis direction as shown in  FIG. 5 , Signal MZ is the force torque signal along the Z-axis direction as shown in  FIG. 5 . 
     Matrix[C] is coefficient matrix, which comes from calibration equipment. In practice, the calibration equipment applies specific force or force torque onto the multi-axis loadcell, the output signals from each channel are recorded, and to obtain the relationship between the signals output from the transducer and the specific force and force torque, then coefficient matrix [C] is obtained. 
     [CH] matrix is the output signal matrix of the multi-axis loadcell. 
     It should be noted that the matrix computation coefficient [C] and [F]=[C][CH] are calculated via microprocessor, or by the specific circuit within the transducer. 
     Referring to  FIG. 7 , it is a schematic illustration of the multi-axis loadcell according the second embodiment of the present invention. 
     Two strain gages are arranged on each of two opposed sides of the force-measuring beam of the multi-axis loadcell according to the second embodiment of the present invention; Two strain gages on one of the opposed sides are arranged in the directions of positive 45° and negative 45° respectively, configured to measure the shearing strains of positive 45° and of negative 45°; the other two strain gages on the other one of the opposed sides are arranged in the directions of longitudinal and transverse respectively, configured to measure the longitudinal strain and transverse strain respectively. 
     As shown in  FIG. 7 , the multi-axis loadcell includes three force-measuring beams, which are force-measuring beam  4   a , force-measuring beam  4   b  and force-measuring beam  4   c . Four strain gages are arranged on each of the above force-measuring beams, the detailed is as follow: 
     Strain gages R 11  and R 13  are arranged on front side of force-measuring beam  4   a  in the directions of longitudinal and transverse respectively; Strain gages R 12  and R 14  are arranged on rear side of force-measuring beam  4   a  in the directions of negative 45° and positive 45° respectively. 
     Strain gages R 21  and R 23  are arranged on front side of force-measuring beam  4   b  in the directions of longitudinal and transverse respectively; Strain gages R 22  and R 24  are arranged on rear side of force-measuring beam  4   b  in the directions of negative 45° and positive 45° respectively. 
     Strain gages R 31  and R 33  are arranged on front side of force-measuring beam  4   c  in the directions of longitudinal and transverse respectively; Strain gages R 32  and R 34  are arranged on rear side of force-measuring beam  4   a  in the directions of negative 45° and positive 45° respectively. 
     In practice, four strain gages arranged on the same side of the force-measuring beam could be stacked together or not stacked. The above two strain gages arranged on the same side of the force-measuring beam could be replaced by strain rosette. 
     The bridge circuit connection and the decoupling principle of the multi-axis loadcell of the second embodiment of the present invention are identical to the first embodiment, so no more detailed description here. 
     Referring to  FIG. 8 , it is a schematic illustration of the multi-axis loadcell according the third embodiment of the present invention. 
     Two strain gages are arranged on each of two opposed sides of the force-measuring beam of the multi-axis loadcell according to the third embodiment of the present invention in the directions of positive 45° and negative 45° respectively, configured to measure the shearing strains of positive 45° and of negative 45°; two strain gages on each of the other two opposed sides are arranged in the directions of longitudinal and transverse respectively, configured to measure the longitudinal strain and transverse strain respectively. 
     As shown in  FIG. 8 , the multi-axis loadcell includes three force-measuring beams, which are force-measuring beam  4   a , force-measuring beam  4   b  and force-measuring beam  4   c . Eight strain gages are arranged on each of the above force-measuring beams, the detailed is as follow: 
     Strain gages R 14  and R 12  are arranged on front side of force-measuring beam  4   a  in the directions of positive 45° and negative 45° respectively; Strain gages R 18  and R 16  are arranged on rear side of force-measuring beam  4   a  in the directions of positive 45° and negative 45° respectively; Strain gages R 11  and R 13  are arranged on left side of force-measuring beam  4   a  in the directions of longitudinal and transverse respectively; Strain gages R 15  and R 17  are arranged on right side of force-measuring beam  4   a  in the directions of longitudinal and transverse respectively. 
     Strain gages R 24  and R 22  are arranged on front side of force-measuring beam  4   b  in the directions of positive 45° and negative 45° respectively; Strain gages R 28  and R 26  are arranged on rear side of force-measuring beam  4   b  in the directions of positive 45° and negative 45° respectively; Strain gages R 21  and R 23  are arranged on left side of force-measuring beam  4   b  in the directions of longitudinal and transverse respectively; Strain gages R 25  and R 27  are arranged on right side of force-measuring beam  4   b  in the directions of longitudinal and transverse respectively. 
     Strain gages R 34  and R 32  are arranged on front side of force-measuring beam  4   c  in the directions of positive 45° and negative 45° respectively; Strain gages R 38  and R 36  are arranged on rear side of force-measuring beam  4   c  in the directions of positive 45° and negative 45° respectively; Strain gages R 31  and R 33  are arranged on left side of force-measuring beam  4   c  in the directions of longitudinal and transverse respectively; Strain gages R 35  and R 37  are arranged on right side of force-measuring beam  4   c  in the directions of longitudinal and transverse respectively. 
     In practice, two strain gages arranged on the same side of the force-measuring beam in the directions of positive 45° and negative 45° respectively could be stacked together or not stacked; two strain gages arranged on the same side of the force-measuring beam in the directions of longitudinal and transverse respectively could be stacked together or not stacked; the above strain gages could be replaced by strain rosette. 
     Referring to  FIG. 9 , it is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the third embodiment of the present invention. 
     There are six signal channels to output signal according to the bridges circuit design of the strain gage, in accordance with the multi-axis loadcell of the third embodiment, which are signals CH 1 , CH 2 , CH 3 , CH 4 , CH 5  and CH 6 . The detailed is as follow: 
     R 11 , R 13 , R 15  and R 17  constitute a bridge circuit as shown in  FIG. 9 , when the flexure is applied on force to produce strain, the resistance changes of R 11 , R 13 , R 15  and R 17  are ΔR 11 , ΔR 13 , ΔR 15  and ΔR 17 , the strain is converted into electrical signal, to obtain signal CH 1 . 
     R 12 , R 14 , R 16  and R 18  constitute a bridge circuit as shown in  FIG. 9 , when the flexure is applied on force to produce strain, the resistance changes of R 12 , R 14 , R 16  and R 18  are ΔR 12 , ΔR 14 , ΔR 16  and ΔR 18 , the strain is converted into electrical signal, to obtain signal CH 2 . 
     R 31 , R 33 , R 35  and R 37  constitute a bridge circuit as shown in  FIG. 9 , when the flexure is applied on force to produce strain, the resistance changes of R 31 , R 33 , R 35  and R 37  are ΔR 31 , ΔR 33 , ΔR 35  and ΔR 37 , the strain is converted into electrical signal, to obtain signal CH 3 . 
     R 32 , R 34 , R 36  and R 38  constitute a bridge circuit as shown in  FIG. 9 , when the flexure is applied on force to produce strain, the resistance changes of R 32 , R 34 , R 36  and R 38  are ΔR 32 , ΔR 34 , ΔR 36  and ΔR 38 , the strain is converted into electrical signal, to obtain signal CH 4 . 
     R 21 , R 23 , R 25  and R 27  constitute a bridge circuit as shown in  FIG. 9 , when the flexure is applied on force to produce strain, the resistance changes of R 21 , R 23 , R 25  and R 27  are ΔR 21 , ΔR 23 , ΔR 25  and ΔR 27 , the strain is converted into electrical signal, to obtain signal CH 5 . 
     R 22 , R 24 , R 26  and R 28  constitute a bridge circuit as shown in  FIG. 9 , when the flexure is applied on force to produce strain, the resistance changes of R 22 , R 24 , R 26  and R 28  are ΔR 22 , ΔR 24 , ΔR 26  and ΔR 28 , the strain is converted into electrical signal, to obtain signal CH 6 . 
     After signals CH 1 , CH 2 , CH 3 , CH  4 , CH 5  and CH 6  output from six channels of the multi-axis loadcell are obtained, they are decoupled via matrix computation, then the value of the force or force torque signals which are applied onto the transducer are obtained. The decoupling principle is identical to the first embodiment, so no more detailed description here. 
     Referring to  FIG. 10 , it is a schematic illustration of the multi-axis loadcell according the fourth embodiment of the present invention. 
     In the fourth embodiment, four strain gages are arranged on each one of two opposed sides of the force-measuring beam in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, configured to measure the longitudinal strain, the transverse strain, and the shearing strains of positive 45° and of negative 45° respectively. 
     As shown in  FIG. 10 , the multi-axis loadcell includes four force-measuring beams, which are force-measuring beam  4   a , force-measuring beam  4   b , force-measuring beam  4   c  and force-measuring beam  4   d . Four strain gages are arranged on the front side and the rear side respectively of each force-measuring beams, the detailed is as follow: 
     Four strain gages are arranged on front side of force-measuring beam  4   a  in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 11 , R 13 , R 14  and R 12  as shown in  FIG. 10 ; 
     Four strain gages are arranged on rear side of force-measuring beam  4   a  in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 15 , R 17 , R 18  and R 16  as shown in  FIG. 10 ; 
     Four strain gages are arranged on front side of force-measuring beam  4   b  in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 21 , R 23 , R 24  and R 22  as shown in  FIG. 10 ; 
     Four strain gages are arranged on rear side of force-measuring beam  4   b  in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 25 , R 27 , R 28  and R 26  as shown in  FIG. 10 ; 
     Four strain gages are arranged on front side of force-measuring beam  4   c  in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 31 , R 33 , R 34  and R 32  as shown in  FIG. 10 ; 
     Four strain gages are arranged on rear side of force-measuring beam  4   c  in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 35 , R 37 , R 38  and R 36  as shown in  FIG. 10 ; 
     Four strain gages are arranged on front side of force-measuring beam  4   d  in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 41 , R 43 , R 44  and R 42  as shown in  FIG. 10 ; 
     Four strain gages are arranged on rear side of force-measuring beam  4   d  in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 45 , R 47 , R 48  and R 46  as shown in  FIG. 10 ; 
     In practice, four strain gages arranged on the same side of the force-measuring beam in the directions of longitudinal, transverse, positive 45° and negative 45° respectively could be stacked together or not stacked. The above four strain gages could be replaced by strain rosette. 
     Referring to  FIG. 11 , it is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the fourth embodiment of the present invention. 
     The fourth embodiment shows bridges circuit design of the strain gage, and there are three force signals FX, FY and FZ, and three force torque signals MX, MY and MZ are obtained. The detailed is as follow: 
     R 26 , R 28 , R 46  and R 48  constitute a bridge circuit as shown in  FIG. 11 , when the flexure is applied on force to produce strain, the resistance changes of R 26 , R 28 , R 46  and R 48  are ΔR 26 , ΔR 28 , ΔR 46  and ΔR 48 , the strain is converted into electrical signal, to obtain signal FX. Wherein, signal FX is the force signal along the X-axis direction shown in  FIG. 10 . 
     R 16 , R 18 , R 36  and R 38  constitute a bridge circuit as shown in  FIG. 11 , when the flexure is applied on force to produce strain, the resistance changes of R 16 , R 18 , R 36  and R 38  are ΔR 16 , ΔR 18 , ΔR 36  and ΔR 38 , the strain is converted into electrical signal, to obtain signal FY. Wherein, signal FY is the force signal along the Y-axis direction shown in  FIG. 10 . 
     R 15 , R 17 , R 25 , R 27 , R 35 , R 37 , R 45  and R 47  constitute a bridge circuit as shown in  FIG. 11 , when the flexure is applied on force to produce strain, the resistance changes of R 15 , R 17 , R 25 , R 27 , R 35 , R 37 , R 45  and R 47  are ΔR 15 , ΔR 17 , ΔR 25 , ΔR 27 , ΔR 35 , ΔR 37 , ΔR 45  and ΔR 47 , the strain is converted into electrical signal, to obtain signal FZ. Wherein, signal FZ is the force signal along the Z-axis direction shown in  FIG. 10 . 
     R 21 , R 23 , R 41  and R 43  constitute a bridge circuit as shown in  FIG. 11 , when the flexure is applied on force to produce strain, the resistance changes of R 21 , R 23 , R 41  and R 43  are ΔR 21 , ΔR 23 , ΔR 41  and ΔR 43 , the strain is converted into electrical signal, to obtain signal MX. Wherein, signal MX is the force torque signal along the X-axis direction shown in  FIG. 10 . 
     R 11 , R 13 , R 31  and R 33  constitute a bridge circuit as shown in  FIG. 11 , when the flexure is applied on force to produce strain, the resistance changes of R 11 , R 13 , R 31  and R 33  are ΔR 11 , ΔR 13 , ΔR 31  and ΔR 33 , the strain is converted into electrical signal, to obtain signal MY. Wherein, signal MY is the force torque signal along the Y-axis direction shown in  FIG. 10 . 
     R 12 , R 14 , R 22 , R 24 , R 32 , R 34 , R 42  and R 44  constitute a bridge circuit as shown in  FIG. 11 , when the flexure is applied on force to produce strain, the resistance changes of R 12 , R 14 , R 22 , R 24 , R 32 , R 34 , R 42  and R 44  are ΔR 12 , ΔR 14 , ΔR 22 , ΔR 24 , ΔR 32 , ΔR 34 , ΔR 42  and ΔR 44 , the strain is converted into electrical signal, to obtain signal MZ. Wherein, signal MZ is the force torque signal along the Z-axis direction shown in  FIG. 10 . 
     It should be noted that the fourth embodiment provides a method for obtaining six signals FX, FY, FZ, MX, MY and MZ. In practice, one or more strain gages with bridges circuit outputting signals could be reduced, so as to obtain less than six signals to output. 
     Referring to  FIG. 12 , it is a schematic illustration of the multi-axis loadcell according the fifth embodiment of the present invention. 
     In the fifth embodiment, five strain gages are arranged on each one of two opposed sides of the force-measuring beam. Four of the strain gages are arranged in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, configured to measure the longitudinal strain, the transverse strain, and the shearing strains of positive 45° and of negative 45° respectively; the other one of the strain gages is arranged in the longitudinal direction, configured to measure the longitudinal strain; 
     As shown in  FIG. 12 , the multi-axis loadcell includes four force-measuring beams, which are force-measuring beam  4   a , force-measuring beam  4   b , force-measuring beam  4   c  and force-measuring beam  4   d . Five strain gages are arranged on the front side and the rear side respectively of each force-measuring beams, the detailed is as follow: 
     Five strain gages are arranged on front side of force-measuring beam  4   a , four of the five strain gages are arranged in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 11 , R 13 , R 14  and R 12  as shown in  FIG. 12 ; the other one of the five strain gages is arranged in the longitudinal direction, which is strain gage R 19  as shown in  FIG. 12 ; 
     Five strain gages are arranged on rear side of force-measuring beam  4   a , four of the five strain gages are arranged in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 15 , R 17 , R 18  and R 16  as shown in  FIG. 12 ; the other one of the five strain gages is arranged in the longitudinal direction, which is strain gage R 10  as shown in  FIG. 12 ; 
     Five strain gages are arranged on front side of force-measuring beam  4   b , four of the five strain gages are arranged in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 21 , R 23 , R 24  and R 22  as shown in  FIG. 12 ; the other one of the five strain gages is arranged in the longitudinal direction, which is strain gage R 29  as shown in  FIG. 12 ; 
     Five strain gages are arranged on rear side of force-measuring beam  4   b , four of the five strain gages are arranged in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 25 , R 27 , R 28  and R 26  as shown in  FIG. 12 ; the other one of the five strain gages is arranged in the longitudinal direction, which us strain gage R 20  as shown in  FIG. 12 ; 
     Five strain gages are arranged on front side of force-measuring beam  4   c , four of the five strain gages are arranged in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 31 , R 33 , R 34  and R 32  as shown in  FIG. 12 ; the other one of the five strain gages is arranged in the longitudinal direction, which us strain gage R 39  as shown in  FIG. 12 ; 
     Five strain gages are arranged on rear side of force-measuring beam  4   c , four of the five strain gages are arranged in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 35 , R 37 , R 38  and R 36  as shown in  FIG. 12 ; the other one of the five strain gages is arranged in the longitudinal direction, which us strain gage R 30  as shown in  FIG. 12 ; 
     Five strain gages are arranged on front side of force-measuring beam  4   d , four of the five strain gages are arranged in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 41 , R 43 , R 44  and R 42  as shown in  FIG. 12 ; the other one of the five strain gages is arranged in the longitudinal direction, which us strain gage R 49  as shown in  FIG. 12 ; 
     Five strain gages are arranged on rear side of force-measuring beam  4   d , four of the five strain gages are arranged in the directions of longitudinal, transverse, positive 45° and negative 45° respectively, which are strain gages R 45 , R 47 , R 48  and R 46  as shown in  FIG. 12 ; the other one of the five strain gages is arranged in the longitudinal direction, which us strain gage R 40  as shown in  FIG. 12 ; 
     In practice, five strain gages arranged on the same side of the force-measuring beam in the directions of longitudinal, transverse, positive 45° and negative 45° respectively could be stacked together or not stacked. The above five strain gages could be replaced by strain rosette. 
     Referring to  FIG. 13 , it is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the fifth embodiment of the present invention. 
     The fifth embodiment shows bridges circuit design of the strain gage, and there are three force signals FX, FY and FZ, and three force torque output signals MX, MY and MZ are obtained. The detailed is as follow: 
     R 26 , R 28 , R 46  and R 48  constitute a bridge circuit as shown in  FIG. 13 , when the flexure is applied on force to produce strain, the resistance changes of R 26 , R 28 , R 46  and R 48  are ΔR 26 , ΔR 28 , ΔR 46  and ΔR 48 , the strain is converted into electrical signal, to obtain signal FX. 
     R 16 , R 18 , R 36  and R 38  constitute a bridge circuit as shown in  FIG. 13 , when the flexure is applied on force to produce strain, the resistance changes of R 16 , R 18 , R 36  and R 38  are ΔR 16 , ΔR 18 , ΔR 36  and ΔR 38 , the strain is converted into electrical signal, to obtain signal FY. 
     R 11 , R 13 , R 15 , R 17 , R 21 , R 23 , R 25 , R 27 , R 31 , R 33 , R 35 , R 37 , R 41 , R 43 , R 45  and R 47  constitute a bridge circuit as shown in  FIG. 13 , when the flexure is applied on force to produce strain, the resistance changes of R 11 , R 13 , R 15 , R 17 , R 21 , R 23 , R 25 , R 27 , R 31 , R 33 , R 35 , R 37 , R 41 , R 43 , R 45  and R 47  are ΔR 11 , ΔR 13 , ΔR 15 , ΔR 17 , ΔR 21 , ΔR 23 , ΔR 25 , ΔR 27 , ΔR 31 , ΔR 33 , ΔR 35 , ΔR 37 , ΔR 41 , ΔR 43 , ΔR 45  and ΔR 47 , the strain is converted into electrical signal, to obtain signal FZ. 
     R 20 , R 29 , R 40  and R 49  constitute a bridge circuit as shown in  FIG. 13 , when the flexure is applied on force to produce strain, the resistance changes of R 20 , R 29 , R 40  and R 49  are ΔR 20 , ΔR 29 , ΔR 40  and ΔR 49 , the strain is converted into electrical signal, to obtain signal MX. 
     R 10 , R 19 , R 30  and R 39  constitute a bridge circuit as shown in  FIG. 13 , when the flexure is applied on force to produce strain, the resistance changes of R 10 , R 19 , R 30  and R 39  are ΔR 10 , ΔR 19 , ΔR 30  and ΔR 39 , the strain is converted into electrical signal, to obtain signal MY. 
     R 12 , R 14 , R 22 , R 24 , R 32 , R 34 , R 42  and R 44  constitute a bridge circuit as shown in  FIG. 13 , when the flexure is applied on force to produce strain, the resistance changes of R 12 , R 14 , R 22 , R 24 , R 32 , R 34 , R 42  and R 44  are ΔR 12 , ΔR 14 , ΔR 22 , ΔR 24 , ΔR 32 , ΔR 34 , ΔR 42 , ΔR 44 , the strain is converted into electrical signal, to obtain signal MZ. 
     It should be noted that the fifth embodiment provides a method for obtaining six signals FX, FY, FZ, MX, MY and MZ. In practice, one or more strain gages with bridges circuit outputting signals could be reduced, so as to obtain less than six signals to output. 
       FIG. 14  is a schematic illustration of the multi-axis loadcell according the sixth embodiment of the present invention. 
     In the sixth embodiment, three strain gages are arranged on each one of two opposed sides of the force-measuring beam. Two of the three strain gages are arranged in the directions positive 45° and negative 45° respectively, configured to measure the shearing strains of positive 45° and of negative 45° respectively; the other one of the strain gages is arranged in the longitudinal direction, configured to measure the longitudinal strain. 
     Two strain gages are arranged on each one of the other two opposed sides of the force-measuring beam in the directions of longitudinal and transverse respectively, configured to measure the longitudinal strain and transverse strain respectively. 
     As shown in  FIG. 14 , the multi-axis loadcell includes four force-measuring beams, which are force-measuring beam  4   a , force-measuring beam  4   b , force-measuring beam  4   c  and force-measuring beam  4   d . Strain gages are arranged on each of four sides respectively of each force-measuring beam, the detailed is as follow: 
     Strain gages R 12 , R 14  and R 19  are arranged on front side of force-measuring beam  4   a ; strain gages R 14  and R 12  are arranged in the directions of positive 45° and of negative 45° respectively; strain gage R 19  is arranged in the longitudinal direction. 
     Strain gages R 16 , R 18  and R 10  are arranged on rear side of force-measuring beam  4   a ; strain gages R 18  and R 16  are arranged in the directions of positive 45° and of negative 45° respectively; strain gage R 10  is arranged in the longitudinal direction. 
     Strain gages R 11  and R 13  are arranged on left side of force-measuring beam  4   a  in the longitudinal direction and the transverse direction respectively; 
     Strain gages R 15  and R 17  are arranged on right side of force-measuring beam  4   a  in the longitudinal direction and the transverse direction respectively. 
     Strain gages R 22 , R 24  and R 29  are arranged on front side of force-measuring beam  4   b ; strain gages R 24  and R 22  are arranged in the directions of positive 45° and of negative 45° respectively; strain gage R 29  is arranged in the longitudinal direction. 
     Strain gages R 26 , R 28  and R 20  are arranged on rear side of force-measuring beam  4   b ; strain gages R 28  and R 26  are arranged in the directions of positive 45° and of negative 45° respectively; strain gage R 20  is arranged in the longitudinal direction. 
     Strain gages R 21  and R 23  are arranged on left side of force-measuring beam  4   b  in the longitudinal direction and the transverse direction respectively. 
     Strain gages R 25  and R 27  are arranged on right side of force-measuring beam  4   b  in the longitudinal direction and the transverse direction respectively. 
     Strain gages R 32 , R 34  and R 39  are arranged on front side of force-measuring beam  4   c ; strain gages R 34  and R 32  are arranged in the directions of positive 45° and of negative 45° respectively; strain gage R 39  is arranged in the longitudinal direction. 
     Strain gages R 36 , R 38  and R 30  are arranged on rear side of force-measuring beam  4   c ; strain gages R 38  and R 36  are arranged in the directions of positive 45° and of negative 45° respectively; strain gage R 30  is arranged in the longitudinal direction. 
     Strain gages R 31  and R 33  are arranged on left side of force-measuring beam  4   c  in the longitudinal direction and the transverse direction respectively. 
     Strain gages R 35  and R 37  are arranged on right side of force-measuring beam  4   c  in the longitudinal direction and the transverse direction respectively. 
     Strain gages R 42 , R 44  and R 49  are arranged on front side of force-measuring beam  4   d ; strain gages R 44  and R 42  are arranged in the directions of positive 45° and of negative 45° respectively; strain gage R 49  is arranged in the longitudinal direction. 
     Strain gages R 46 , R 48  and R 40  are arranged on rear side of force-measuring beam  4   d ; strain gages R 48  and R 46  are arranged in the directions of positive 45° and of negative 45° respectively; strain gage R 40  is arranged in the longitudinal direction. 
     Strain gages R 41  and R 43  are arranged on left side of force-measuring beam  4   d  in the longitudinal direction and the transverse direction respectively. 
     Strain gages R 45  and R 47  are arranged on right side of force-measuring beam  4   d  in the longitudinal direction and the transverse direction respectively. 
     In practice, strain gages arranged on the same side of the force-measuring beam could be stacked together or not stacked. The above two or three strain gages which are arranged on the same side of the force-measuring beam could be replaced by strain rosette. 
       FIG. 15  is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the sixth embodiment of the present invention. 
     The sixth embodiment shows bridges circuit design of the strain gage, and there are three force signals FX, FY and FZ, and three force torque output signals MX, MY and MZ are obtained. The detailed is as follow: 
     R 26 , R 28 , R 46  and R 48  constitute a bridge circuit as shown in  FIG. 15 , when the flexure is applied on force to produce strain, the resistance changes of R 26 , R 28 , R 46  and R 48  are ΔR 26 , ΔR 28 , ΔR 46  and ΔR 48 , the strain is converted into electrical signal, to obtain signal FX. 
     R 16 , R 18 , R 36  and R 38  constitute a bridge circuit as shown in  FIG. 15 , when the flexure is applied on force to produce strain, the resistance changes of R 16 , R 18 , R 36  and R 38  are ΔR 16 , ΔR 18 , ΔR 36  and ΔR 38 , the strain is converted into electrical signal, to obtain signal FY. 
     R 11 , R 13 , R 15 , R 17 , R 21 , R 23 , R 25 , R 27 , R 31 , R 33 , R 35 , R 37 , R 41 , R 43 , R 45  and R 47  constitute a bridge circuit as shown in  FIG. 15 , when the flexure is applied on force to produce strain, the resistance changes of R 11 , R 13 , R 15 , R 17 , R 21 , R 23 , R 25 , R 27 , R 31 , R 33 , R 35 , R 37 , R 41 , R 43 , R 45  and R 47  are ΔR 11 , ΔR 13 , ΔR 15 , ΔR 17 , ΔR 21 , ΔR 23 , ΔR 25 , ΔR 27 , ΔR 31 , ΔR 33 , ΔR 35 , ΔR 37 , ΔR 41 , ΔR 43 , ΔR 45  and ΔR 47 , the strain is converted into electrical signal, to obtain signal FZ. 
     R 20 , R 29 , R 40  and R 49  constitute a bridge circuit as shown in  FIG. 15 , when the flexure is applied on force to produce strain, the resistance changes of R 20 , R 29 , R 40  and R 49  are ΔR 20 , ΔR 29 , ΔR 40  and ΔR 49 , the strain is converted into electrical signal, to obtain signal MX. 
     R 10 , R 19 , R 30  and R 39  constitute a bridge circuit as shown in  FIG. 15 , when the flexure is applied on force to produce strain, the resistance changes of R 10 , R 19 , R 30  and R 39  are ΔR 10 , ΔR 19 , ΔR 30  and ΔR 39 , the strain is converted into electrical signal, to obtain signal MY. 
     R 12 , R 14 , R 22 , R 24 , R 32 , R 34 , R 42  and R 44  constitute a bridge circuit as shown in  FIG. 15 , when the flexure is applied on force to produce strain, the resistance changes of R 12 , R 14 , R 22 , R 24 , R 32 , R 34 , R 42  and R 44  are ΔR 12 , ΔR 14 , ΔR 22 , ΔR 24 , ΔR 32 , ΔR 34 , ΔR 42 , ΔR 44 , the strain is converted into electrical signal, to obtain signal MZ. 
     It should be noted that the sixth embodiment provides a method for obtaining six signals FX, FY, FZ, MX, MY and MZ. In practice, one or more strain gages with bridges circuit outputting signals could be reduced, so as to obtain less than six signals to output. 
       FIG. 16  is a schematic illustration of the multi-axis loadcell according the seventh embodiment of the present invention. 
     According to the multi-axis loadcell of the seventh embodiment, four strain gages are arranged on each one of two opposed sides of the force-measuring beam; two of the strain gages are arranged on an upper portion and a lower portion of the force-measuring beam in the longitudinal direction, configured to measure longitudinal strain of the upper portion and the lower portion of the force-measuring beam; the other two of the strain gages are arranged in the middle portion of the force-measuring beam in the longitudinal direction and transverse direction, configured to measure longitudinal strain and the transverse strain of the middle portion of the force-measuring beam; 
     five strain gages are arranged on one of the other two opposed sides of the force-measuring beam; three of the five strain gages are arranged on an upper portion, a middle portion and a lower portion of the force-measuring beam in the longitudinal direction, configured to measure longitudinal strain of the upper portion, the middle portion and the lower portion; the other two of the five strain gages are arranged on the middle portion of the force-measuring beam in the positive 45° direction and the negative 45° direction, configured to measure the shearing strains of positive 45° and of negative 45° of the middle portion of the force-measuring beam; three strain gages are arranged on an upper portion, a middle portion and a lower portion in the longitudinal direction on the other one of the two opposed sides, configured to measure longitudinal strain of the upper portion, the middle portion and the lower portion of the force-measuring beam. 
     As shown in  FIG. 16 , the multi-axis loadcell includes four force-measuring beams, which are force-measuring beam  4   a , force-measuring beam  4   b , force-measuring beam  4   c  and force-measuring beam  4   d . Strain gages are arranged on the each of four sides respectively of each force-measuring beam, the detailed is as follow: 
     Strain gages R 101 , R 102 , R 103 , R 104  and R 105  are arranged on front side of force-measuring beam  4   a ; strain gages R 101 , R 102  and R 105  are arranged on an upper portion, a middle portion and a lower portion of the front side in the longitudinal direction; strain gages R 104  and R 103  are arranged in the middle portion of the front side in the directions of positive 45° and of negative 45° respectively. 
     Strain gages R 110 , R 107  and R 106  are arranged on an upper portion, a middle portion and a lower portion of rear side of force-measuring beam  4   a;    
     Strain gages R 111 , R 112 , R 113  and R 114  are arranged on left side of force-measuring beam  4   a ; strain gages R 114  and R 111  are arranged on an upper portion and a lower portion of the left side in the longitudinal direction; strain gages R 112  and R 113  are arranged in the middle portion of the left side in the longitudinal direction and in the transverse direction. 
     Strain gages R 115 , R 116 , R 117  and R 118  are arranged on right side of force-measuring beam  4   a ; strain gages R 118  and R 115  are arranged on an upper portion and a lower portion of the right side in the longitudinal direction; strain gages R 116  and R 117  are arranged in the middle portion of the right side in the longitudinal direction and in the transverse direction. 
     Strain gages R 201 , R 202 , R 203 , R 204  and R 205  are arranged on front side of force-measuring beam  4   b ; strain gages R 205 , R 202  and R 201  are arranged on an upper portion, a middle portion and a lower portion of the front side in the longitudinal direction; strain gages R 204  and R 203  are arranged in the middle portion of the front side in the directions of positive 45° and of negative 45° respectively. 
     Strain gages R 210 , R 207  and R 206  are arranged on an upper portion, a middle portion and a lower portion of rear side of force-measuring beam  4   b;    
     Strain gages R 211 , R 212 , R 213  and R 214  are arranged on left side of force-measuring beam  4   b ; strain gages R 214  and R 211  are arranged on an upper portion and a lower portion of the left side in the longitudinal direction; strain gages R 212  and R 213  are arranged in the middle portion of the left side in the longitudinal direction and in the transverse direction. 
     Strain gages R 215 , R 216 , R 217  and R 218  are arranged on right side of force-measuring beam  4   b ; strain gages R 218  and R 215  are arranged on an upper portion and a lower portion of the right side in the longitudinal direction; strain gages R 216  and R 217  are arranged in the middle portion of the right side in the longitudinal direction and in the transverse direction. 
     Strain gages R 301 , R 302 , R 303 , R 304  and R 305  are arranged on front side of force-measuring beam  4   c ; strain gages R 305 , R 302  and R 301  are arranged on an upper portion, a middle portion and a lower portion of the front side in the longitudinal direction; strain gages R 304  and R 303  are arranged in the middle portion of the front side in the directions of positive 45° and of negative 45° respectively. 
     Strain gages R 310 , R 307  and R 306  are arranged on an upper portion, a middle portion and a lower portion of rear side of force-measuring beam  4   c;    
     Strain gages R 311 , R 312 , R 313  and R 314  are arranged on left side of force-measuring beam  4   c ; strain gages R 314  and R 311  are arranged on an upper portion and a lower portion of the left side in the longitudinal direction; strain gages R 312  and R 313  are arranged in the middle portion of the left side in the longitudinal direction and in the transverse direction. 
     Strain gages R 315 , R 316 , R 317  and R 318  are arranged on right side of force-measuring beam  4   c ; strain gages R 318  and R 315  are arranged on an upper portion and a lower portion of the right side in the longitudinal direction; strain gages R 316  and R 317  are arranged in the middle portion of the right side in the longitudinal direction and in the transverse direction. 
     Strain gages R 401 , R 402 , R 403 , R 404  and R 405  are arranged on front side of force-measuring beam  4   d ; strain gages R 405 , R 402  and R 401  are arranged on an upper portion, a middle portion and a lower portion of the front side in the longitudinal direction; strain gages R 404  and R 403  are arranged in the middle portion of the front side in the directions of positive 45° and of negative 45° respectively. 
     Strain gages R 410 , R 407  and R 406  are arranged on an upper portion, a middle portion and a lower portion of rear side of force-measuring beam  4   d;    
     Strain gages R 411 , R 412 , R 413  and R 414  are arranged on left side of force-measuring beam  4   d ; strain gages R 414  and R 411  are arranged on an upper portion and a lower portion of the left side in the longitudinal direction; strain gages R 412  and R 413  are arranged in the middle portion of the left side in the longitudinal direction and in the transverse direction. 
     Strain gages R 415 , R 416 , R 417  and R 418  are arranged on right side of force-measuring beam  4   d ; strain gages R 418  and R 415  are arranged on an upper portion and a lower portion of the right side in the longitudinal direction; strain gages R 416  and R 417  are arranged in the middle portion of the right side in the longitudinal direction and in the transverse direction. 
     In practice, two strain gages arranged on the same side of the force-measuring beam in the directions of positive 45° and negative 45° respectively could be stacked together or not stacked; two strain gages arranged on the same side of the force-measuring beam in the directions of longitudinal and of transverse respectively could be stacked together or not stacked. The above strain gages could be replaced by strain rosette. 
       FIG. 17  is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the seventh embodiment of the present invention. 
     The seventh embodiment shows bridges circuit design of the strain gage, and there are three force signals FX, FY and FZ, and three force torque output signals MX, MY and MZ are obtained. The detailed is as follow: 
     R 105 , R 106 , R 214 , R 215 , R 301 , R 310 , R 411 , R 418 , R 101 , R 110 , R 211 , R 218 , R 305 , R 306 , R 414  and R 415  constitute a bridge circuit as shown in  FIG. 17 , when the flexure is applied on force to produce strain, the resistance changes of R 105 , R 106 , R 214 , R 215 , R 301 , R 310 , R 411 , R 418 , R 101 , R 110 , R 211 , R 218 , R 305 , R 306 , R 414  and R 415  are ΔR 105 , ΔR 106 , ΔR 214 , ΔR 215 , ΔR 301 , ΔR 310 , ΔR 411 , ΔR 418 , ΔR 101 , ΔR 110 , ΔR 211 , Δ 218 , ΔR 305 , ΔR 306 , ΔR 414  and ΔR 415 , the strain is converted into electrical signal, to obtain signal FX. 
     R 114 , R 115 , R 201 , R 210 , R 311 , R 318 , R 405 , R 406 , R 111 , R 118 , R 205 , R 206 , R 314 , R 315 , R 410  and R 401  constitute a bridge circuit as shown in  FIG. 17 , when the flexure is applied on force to produce strain, the resistance changes of R 114 , R 115 , R 201 , R 210 , R 311 , R 318 , R 405 , R 406 , R 111 , R 118 , R 205 , R 206 , R 314 , R 315 , R 410  and R 401  are ΔR 114 , ΔR 115 , ΔR 201 , ΔR 210 , ΔR 311 , ΔR 318 , ΔR 405 , ΔR 406 , ΔR 111 , ΔR 118 , ΔR 205 , ΔR 206 , ΔR 314 , ΔR 315 , ΔR 410  and ΔR 401 , the strain is converted into electrical signal, to obtain signal FY. 
     R 113 , R 117 , R 213 , R 217 , R 313 , R 317 , R 413 , R 417 , R 112 , R 116 , R 212 , R 216 , R 312 , R 316 , R 412  and R 416  constitute a bridge circuit as shown in  FIG. 17 , when the flexure is applied on force to produce strain, the resistance changes of R 113 , R 117 , R 213 , R 217 , R 313 , R 317 , R 413 , R 417 , R 112 , R 116 , R 212 , R 216 , R 312 , R 316 , R 412  and R 416  are ΔR 113 , ΔR 117 , ΔR 213 , ΔR 217 , ΔR 313 , ΔR 317 , ΔR 413 , ΔR 417 , ΔR 112 , ΔR 116 , ΔR 212 , ΔR 216 , ΔR 312 , ΔR 316 , ΔR 412  and ΔR 416 , the strain is converted into electrical signal, to obtain signal FZ. 
     R 202 , R 207 , R 402  and R 407  constitute a bridge circuit as shown in  FIG. 17 , when the flexure is applied on force to produce strain, the resistance changes of R 202 , R 207 , R 402  and R 407  are ΔR 202 , ΔR 207 , ΔR 402  and ΔR 407 , the strain is converted into electrical signal, to obtain signal MX. 
     R 102 , R 107 , R 302  and R 307  constitute a bridge circuit as shown in  FIG. 17 , when the flexure is applied on force to produce strain, the resistance changes of R 102 , R 107 , R 302  and R 307  are ΔR 102 , ΔR 107 , ΔR 302  and ΔR 307 , the strain is converted into electrical signal, to obtain signal MY. 
     R 103 , R 104 , R 203 , R 204 , R 303 , R 304 , R 403  and R 404  constitute a bridge circuit as shown in  FIG. 17 , when the flexure is applied on force to produce strain, the resistance changes of R 103 , R 104 , R 203 , R 204 , R 303 , R 304 , R 403  and R 404  are ΔR 103 , ΔR 104 , ΔR 203 , ΔR 204 , ΔR 303 , ΔR 304 , ΔR 403  and ΔR 404 , the strain is converted into electrical signal, to obtain signal MZ. 
     It should be noted that the seventh embodiment provides a method for obtaining six signals FX, FY, FZ, MX, MY and MZ. In practice, one or more strain gages with bridges circuit outputting signals could be reduced, so as to obtain less than six signals to output. 
       FIG. 18  is a schematic illustration of the multi-axis loadcell according the eighth embodiment of the present invention. 
     According to the multi-axis loadcell of the eighth embodiment, four strain gages are arranged on one of two opposed sides of the force-measuring beam respectively in the directions of longitudinal, transverse, positive 45° and negative 45°, configured to measure the strains in longitudinal and transverse directions, and shearing strains in positive 45° and negative 45° directions; 
     four strain gages are arranged on the other one of two opposed sides of the force-measuring beam respectively, two of the strain gages are arranged in longitudinal direction, configured to measure the longitudinal strain; the other two of the strain gages are arranged in the directions positive 45° and negative 45°, configured to measure the shearing strains of positive 45° and negative 45°. 
     As shown in  FIG. 18 , the multi-axis loadcell includes four force-measuring beams, which are force-measuring beam  4   a , force-measuring beam  4   b , force-measuring beam  4   c  and force-measuring beam  4   d . Strain gages are arranged on the each of front side and rear side of each force-measuring beam, the detailed is as follow: 
     Four strain gages are arranged on front side of force-measuring beam  4   a ; two strain gages R 11  and R 13  are arranged in the longitudinal direction as shown in  FIG. 18 ; the other two strain gages R 14  and R 12  are arranged in the directions of positive 45° and of negative 45° respectively as shown in  FIG. 18 . 
     Four strain gages R 15 , R 17 , R 18  and R 16  are arranged on rear side of force-measuring beam  4   a  in the directions of longitudinal, transverse and positive 45° and negative 45° respectively as shown in  FIG. 18 . 
     Four strain gages are arranged on front side of force-measuring beam  4   b ; two strain gages R 21  and R 23  are arranged in the longitudinal direction as shown in  FIG. 18 ; the other two strain gages R 24  and R 22  are arranged in the directions of positive 45° and of negative 45° respectively as shown in  FIG. 18 . 
     Four strain gages R 25 , R 27 , R 28  and R 26  are arranged on rear side of force-measuring beam  4   b  in the directions of longitudinal, transverse and positive 45° and negative 45° respectively as shown in  FIG. 18 . 
     Four strain gages are arranged on front side of force-measuring beam  4   c ; two strain gages R 31  and R 33  are arranged in the longitudinal direction as shown in  FIG. 18 ; the other two strain gages R 34  and R 32  are arranged in the directions of positive 45° and of negative 45° respectively as shown in  FIG. 18 . 
     Four strain gages R 35 , R 37 , R 38  and R 36  are arranged on rear side of force-measuring beam  4   c  in the directions of longitudinal, transverse and positive 45° and negative 45° respectively as shown in  FIG. 18 . 
     Four strain gages are arranged on front side of force-measuring beam  4   d ; two strain gages R 41  and R 43  are arranged in the longitudinal direction as shown in  FIG. 18 ; the other two strain gages R 44  and R 42  are arranged in the directions of positive 45° and of negative 45° respectively as shown in  FIG. 18 . 
     Four strain gages R 45 , R 47 , R 48  and R 26  are arranged on rear side of force-measuring beam  4   d  in the directions of longitudinal, transverse and positive 45° and negative 45° respectively as shown in  FIG. 18 . 
     In practice, four strain gages arranged on the same side of the force-measuring beam could be stacked together or not stacked. The above strain gages arranged on the same side of the force-measuring beam could be replaced by strain rosette. 
       FIG. 19  is a schematic illustration of the bridge connections of the strain gage of the multi-axis loadcell according to the eighth embodiment of the present invention. 
     The eighth embodiment shows bridges circuit design of the strain gage, and there are three force signals FX, FY and FZ, and three force torque output signals MX, MY and MZ are obtained. The detailed is as follow: 
     R 26 , R 28 , R 46  and R 48  constitute a bridge circuit as shown in  FIG. 19 , when the flexure is applied on force to produce strain, the resistance changes of R 26 , R 28 , R 46  and R 48  are ΔR 26 , ΔR 28 , ΔR 46  and ΔR 48 , the strain is converted into electrical signal, to obtain signal FX. 
     R 16 , R 18 , R 36  and R 38  constitute a bridge circuit as shown in  FIG. 19 , when the flexure is applied on force to produce strain, the resistance changes of R 16 , R 18 , R 36  and R 38  are ΔR 16 , ΔR 18 , ΔR 36  and ΔR 38 , the strain is converted into electrical signal, to obtain signal FY. 
     R 15 , R 17 , R 25 , R 27 , R 35 , R 37 , R 45  and R 47 , constitute a bridge circuit as shown in  FIG. 19 , when the flexure is applied on force to produce strain, the resistance changes of R 15 , R 17 , R 25 , R 27 , R 35 , R 37 , R 45  and R 47  are ΔR 15 , ΔR 17 , ΔR 25 , ΔR 27 , ΔR 35 , ΔR 37 , ΔR 45  and ΔR 47 , the strain is converted into electrical signal, to obtain signal FZ. 
     R 21 , R 23 , R 41  and R 43  constitute a bridge circuit as shown in  FIG. 19 , when the flexure is applied on force to produce strain, the resistance changes of R 21 , R 23 , R 41  and R 43  are ΔR 21 , ΔR 23 , ΔR 41  and ΔR 43 , the strain is converted into electrical signal, to obtain signal MX. 
     R 11 , R 13 , R 31  and R 33  constitute a bridge circuit as shown in  FIG. 19 , when the flexure is applied on force to produce strain, the resistance changes of R 11 , R 13 , R 31  and R 33  are ΔR 11 , ΔR 13 , ΔR 31  and ΔR 33 , the strain is converted into electrical signal, to obtain signal MY. 
     R 12 , R 14 , R 22 , R 24 , R 32 , R 34 , R 42  and R 44  constitute a bridge circuit as shown in  FIG. 19 , when the flexure is applied on force to produce strain, the resistance changes of R 12 , R 14 , R 22 , R 24 , R 32 , R 34 , R 42  and R 44  are ΔR 12 , ΔR 14 , ΔR 22 , ΔR 24 , ΔR 32 , ΔR 34 , ΔR 42  and ΔR 44 , the strain is converted into electrical signal, to obtain signal MZ. 
     It should be noted that the eighth embodiment provides a method for obtaining six signals FX, FY, FZ, MX, MY and MZ. In practice, one or more strain gages with bridges circuit outputting signals could be reduced, so as to obtain less than six signals to output. 
     The multi-axis loadcells according to the embodiments of the present invention have the advantages as bellow: 
     1. The multi-axis loadcell according to the present invention includes a flexure and strain gages, with the strain gages being arranging on the force-measuring beams. When the multi-axis loadcell is applied on force, the flexure produces strain, and converts the strain into electrical signal to output. This multi-axis loadcell allows for convenient installment, and is characteristic of simple construction, could achieve not only structure decoupling but also algorithm decoupling, and enables to measure the force signal value and torque signal value which are applied onto the transducer. 
     2. The multi-axis loadcell of the present invention is equipped with top supports and bottom supports which are engaged with each other correspondingly, adapted for serving the function of overload protection, avoiding damaging the transducer, and adjusting to the extreme and complicated operation demand. 
     While the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.