JPS59151032A - Evaluating and calibrating jig of force sensor - Google Patents

Abstract

PURPOSE:To execute exactly evaluation and calibration of a force sensor by constituting the force sensor so that an external force is applied separately in accordance with total six elements, respectively, consisting of three elements of force and three elements of a moment. CONSTITUTION:A force transfer means to a force sensor is connected to the force sensor through a shaft supported by a frame, a pulley fitted to these shaft, and a projection provided on a disk, and constituted of a rope extended to an optional pulley, and a weight hanged on its tip. When a load Fx of Fy is applied to the force sensor, and when a load Fz is applied, an output is generated from strain gauges 14-17, and strain gauges 10-13, respectively. Also, when a load Mx is applied, when a load My is applied, and when a load Mz is applied, an output is generated from the strain gauges 11, 13, the strain gauges 10, 12 and the strain gauges 14-17, respectively. In this way, the output appears in only the strain gauge corresponding to the load, and evaluation and calibration of the force sensor are executed exatly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a jig for evaluating and calibrating a force sensor used for feedback control of a robot.

[Prior art] In the conventional technology for evaluating and calibrating this type of force sensor, it is not possible to apply a load to the force sensor separately into 6 elements (6 force elements and 3 moment elements), and therefore it is difficult to evaluate and calibrate the force sensor. There was a drawback that it could not be done accurately.

Hereinafter, the structure and principle of a force sensor used in a robot or the like, and the prior art in relation to the six elements of force and moment will be further explained.

Conventional robots were mainly of the type that performed only predetermined movements, such as teaching's layback. However, as the applications of robots expand, force sensors for robots have been developed that require control to optimize the robot by attaching a force sensor or the like and using signals from the sensor.

FIG. 1 shows the structure of a force sensor, FIG. 2 shows an example of how the force sensor is used in a robot, and FIG. 3 shows the position of a strain gauge on the force sensor.

The force sensor 1 shown in these figures consists of eight elastic beams 2 to 9.
And, the elasticity is 8 ffi in total, consisting of 4 strain gauges 10 to 16 pasted one on each side 2 to 5 and four strain gauges 14 to 17 pasted two on elastic edge 8.9.
Strain gauges 10 to 17 are constructed of strain gauges 10 to 17, and the elasticity is caused by applying force to strain gauges 2 to 9.
7 is the principle of detection.

Note 1. The number 18 in Figure 2 indicates the robot's arm, which has 1 rigid body and 6 degrees of freedom. In other words, in a three-dimensional space, there is a force element of 31 degrees and a moment element of 3 f degrees, and when expressed in rectangular coordinates, the force in the X-axis direction (hereinafter referred to as F
x), force in the Y-axis direction (hereinafter referred to as Fy), force in the X-axis direction (hereinafter referred to as Fz), moment around X@ (hereinafter referred to as IVx), moment around Y@ (hereinafter referred to as ray), and finally around the Z axis.

moment (hereinafter referred to as "Viz"), and has a total of six elements.

Corresponding to the six elements of force and moment, the load detection of Fz and MxMY applied to the force sensor 1 is performed using strain gauges 10, 11, 12, and 15, and Fx
, Fy,, Fz load detection LD strain gauge 14
．． It is scheduled to take place on 15.16.17.

The elasticity of the eight pieces in the force sensor 1 is 92 to 9.
The following equation generally holds between the output and load of the strain gauges 10 to 17 to which VC is attached.

Li=C,E where F: Load vector E: Output vector C: Transformation matrix The approximate linearity of each coefficient of the transformation matrix C is determined at the design stage, but
It is extremely difficult to obtain accurate values in advance due to the effects of design accuracy, dimensional errors, nonlinearity or drift of strain gauges, etc. Therefore, the most practical technique for evaluating and calibrating the force sensor 1 is to apply a load whose value is known to the force sensor after the force sensor is completed, and to obtain the coefficient by measuring the output. However, this requires the load to be applied by accurately separating it into six elements: force and moment.

However, with conventional technology that applies a load by pressing a spring balance, for example, it is difficult to apply the load separately to the six elements of force and moment.
There was a drawback that it was not possible to accurately evaluate and calibrate force sensors.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art and provide a jig for evaluating and calibrating a force sensor that can accurately evaluate and calibrate a force sensor in correspondence with the six elements of force and moment.

[Summary of the invention]

In the present invention, a force sensor is fixed by a holding means, a force transmitting means is arranged around the force sensor corresponding to six elements of force and moment in a three-dimensional space, and the six elements are transmitted through the nuclear force transmitting means. By configuring the structure so that an external force can be applied to each of them individually, it is possible to accurately evaluate and calibrate the case/su.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on the drawings.

4 to 14 show one embodiment of the present invention. .

In the embodiment shown in these figures, the force sensor 1 is fixed in a frame unit 23 via a holding means, and the holding means is composed of a block 19 and a bolt 20 for fixing the force sensor. 6, the force sensor 1 is fixed by bolts 20 to a block 19, which in turn is fixed to an intermediate horizontal support member 40.41 of the framework 26. As shown in FIG.

In addition, as shown in FIG. 6, the force sensor 1 has a bolt 2
A disk 21 is attached through the force sensor 2 so that a load as an external force is applied to the force sensor 1 through the disk 21. Further, force transmitting means are arranged around the force sensor 1 in correspondence to a total of six elements, three force elements and three moment elements in three-dimensional space, and the force transmitting means is supported by a framework 26. Outer shafts 42-62, pulleys 63-10 attached to these @42-62
force sensor 1 through the protrusion 108 provided on the disc 21.
A rope 109 hung on an arbitrary pulley
, and a weight 1 suspended from the end of the rope 1119
10. As shown in FIG. 11, the force sensor 1 includes a gorif 5.77 attached to the shaft 46, two ropes 109 hung from the disk 21 to each pulley 75.77, and each rope. A force transmission means consisting of a weight 110 suspended from the shaft 109 increases the load of Fx by 7"0, and as shown in FIG. A load of Fy is applied by a force transmission means composed of two ropes 109 hung from the disc 21 to each pulley 78.8DK and a weight 110 suspended from the valley rope 109, as shown in FIG. As shown, the Goo!J 99 attached to the shaft 54.42
．． 64 A rope 109 is hung from the disc 21 to the pulley 99.64, and a weight 1 is suspended from this.
10 A pulley 100.70 attached to a shaft 55.44 supported around the disc 21 at a position 1801 degrees symmetrical to the shaft 54.42, a pulley 100.70 from the disc 21
A rope 109 is hung across the rope 109 , a set of weights 110 are suspended from the rope 109 , and the shaft 5 is attached to the rotation of the disc 21 .
A pulley 103.67 is attached to a shaft 58.43 supported at a position 90 degrees symmetrical to 4.42, and one rope 10 is hung from the disc 21 to the pulley 1'03,67.
9. A weight 110 suspended from this, a pulley 101.73 attached to a shaft 56.45 supported around the disc 21 at a position 180 degrees symmetrical to the shaft 58.46, and a pulley 101.73 from the disc 21. A load of Fz is applied by a force transmission means composed of a rope 109 hung over a pulley 101.76 and a set of weights 110 suspended from the rope 109.
As shown in FIG. 16, a pulley 10173 is attached to the shaft 56.45, a rope 109 is hung from the disk 21 to the pulley 101.73, and a suspended weight 110 and the shaft 56 around the disk 21.
．． 45 and a shaft 62.51 supported in a 180 degree symmetrical position
The pulley 107.91 attached to the
The pulley 107 is pulled out in the opposite direction in the axial direction.
．． As shown in FIG. 16, a load Mx is applied to the shaft 54 by a force transmitting means composed of a rope 109 hung across the rope 91 and a set of weights 110 suspended from the rope 109. Pulley 99.64 attached to .42,
A rope 109 is hung from the disc 21 to the pulley 99.64 (/c). One pulley 105.94 mounted on the !11160.52 supported by the said pulley 99 from the disk 21
．． A rope 109 is pulled out in two axial directions opposite to the rope 109 hung on the pulley 105.94, and a weight 1 is suspended from the rope 109
A load of My is observed by the force transmitting means composed of 10 sets of P and K, and as shown in FIG. The pulleys 77.80.83.86 are supported on the shafts 46.47.4849 and are pulled out in the centrifugal direction at intervals of 90 degrees around the disc 21, and the pulleys 77. A load of Mz is applied by a force transmitting means composed of four ropes 109 hung on 80, 83, and 86 and a weight 110 suspended from these.

Therefore, Fx in detecting the load applied to the force sensor 1
, FyS, and Fz outputs for loads are shown in Figures 1 and 3.
The outputs for the loads of strain gauges 14, 15, 16, and 17 shown in the figure, pz, tnx, and My appear only in strain gauge 10, 11, 12, and 13.

In this way, it is possible to individually apply loads as external forces to the force sensor 1 in correspondence with the six elements of force and moment, and as a result, the strain gauges 10 to 17 have accurate outputs corresponding to the loads. , the force sensor 1 can be accurately evaluated and calibrated.

Next, the embodiments shown in FIGS. 4 to 14 will be described in more detail.

The embodiment shown in these figures includes means for holding the force sensor 1, a framework 26, and means for transmitting force to the force sensor 1.

As shown in FIG. 6, the holding means for the force sensor 1 includes a block 19 and a bolt 20 for fixing the force sensor,
The force sensor 1 is fixed to a block 19 via a bolt 20, and the block 19 is attached to an intermediate horizontal support member 40 of a framework 23.
．． By fixing 41, the force sensor 1 is kept stationary.

As shown in FIG. 6, a disk 21 is attached to the force sensor 1 via bolts 22, and an external force is applied to the force sensor 1 through the disk 21.

The framework 26 is connected to the vertical support member 2, as shown in FIG.
4 to 27, horizontal support members 28 to 55, intermediate vertical support members 66 to 39, and intermediate horizontal support members 40 and 41.

As shown in FIGS. 4, 5, and 7 to 14, the force transmitting means to the force sensor 1 includes shafts 42 to 62 supported by the framework 26 and attached to these shafts 42 to 62. The attached pulleys 63 to 107, the protrusion 10 provided on the disc 21
8 to the force sensor 1 and predetermined pulleys 63~
107, and a weight 110 suspended from the end of the rope 109. As shown in FIG. 7, three pieces each are attached to the shafts 46, 47, 48, and 49 supported at 90 degree intervals on the rotary shaft in the middle part of the disk 21 in the height direction. The middle part of the pool is 6.79.828
The five-piece disc 21 is arranged in alignment with the center thereof, and the pulleys 75, 78, 81, 84 and 77, 8083, on the sides thereof.
The pulleys 76, 79 . 86 are connected to the pulleys 76 , 79 .
82. Distance d equal to 1 of the diameter of the disk 21゛ from 85
As shown in Fig. 8,
The goulifs 5 to 86 are arranged at intervals equal to the radius of the pulleys 75 to 86 so that the rope 109 can be pulled out straight from the middle part of the disc 21 in the height direction. In addition, as shown in FIG. 9, the pulley 99.10'
0,101103 is Z from one end of the disk 21 in the diametrical direction
Axial direction.

The pulleys 99.100.101.103 are arranged at intervals equal to the radius of the pulleys 99.100.101.103 so as to be able to pull out the rope 109 immediately towards one of the
7, so that the rope 109 can be pulled out straight from the other end in the diametrical direction of the disk 21 toward the other end in the Z-axis direction.
They are arranged at intervals equal to the radius of the pulleys 104-107. In the illustrated embodiment, as shown in FIG. 10, the weight 110 includes a weight 111 having a hook 113 at both ends, and a weight 111 having a hook 114 only at one end.
2 can be connected as many times as necessary, and the end of the rope 109 is tied to a hook 116 at one end of the weight 111 or a hook 114 of the weight 112. The force transmitting means is constructed as follows, corresponding to the six elements of force and moment. (I) The force transmitting means for applying the load Fx is a pulley 75.7 attached to the shaft 46, as shown in FIG.
7. It is composed of two ropes 109 pulled out from the disc 21 and hung on each pulley 75, 77, and a weight 110 suspended from each rope 109.

(If) The force transmitting means for applying the load Fy is the pulley 7 attached to the shaft 47, as shown in FIG.
8.80, pulled out from the disc 21 and each pulley 78.
Two ropes 109 hung on 8o, each rope 109
It is composed of a weight 110 suspended from.

(1) The force transmitting means that applies the loads F and z is the 12th
As shown in the figure, the goo'
) 99.64, pulled out from the disc 21 and boo 99
A rope 109 hung over 9.64, a weight 110 suspended from the rope, a shaft 55 supported on the rotation of the disc 21 at a position 180 degrees symmetrical to the shaft 54.42, 4
The pulley 100.70 attached to the 4Ktab, one loca 09 hung across the pulley 100.70 that has not been pulled out from the disc 21, and the set of weight 110 suspended from it, and the rotation of the disc 21. A gooey 106.67 attached to a shaft 58.46 supported at a position 90 degrees symmetrical to the shaft 54.42 is pulled out from the disc 21 and a boot 910
6.67, a rope 109 suspended from the rope 109, a weight 110 suspended from the rope, and six shafts 56.
A pulley 101.73 is attached to a pulley 101.73 attached to the disk 21, and a rope 109 is pulled out from the disc 21 and hung across the pulley 101.73.A weight 110 is suspended from this rope.
It consists of a pair of

(IV) The force transmission means that applies the load Mx has a capacity of 15
As shown, a gauge 101.73 mounted on the shaft 56.45, drawn out from the disk 21 and pulled out from the pulley 10
A rope 109 is hung over a length of 1.76, and a set of weights 110 are suspended from the rope.

A boley 1 is supported around the disc 21 at a position 180 degrees symmetrical to the shaft 56.45 and is attached to the shaft 62.51.
07.91, a rope 109 is pulled out from the disk 21 to the pulley 101.73 and a rope 109 is pulled out in the opposite direction in the force direction and is hung across the pulley 107.91. A weight 110 suspended from
It consists of a pair of

As shown in FIG.
99.64, pulled out from the disc 21 and the boule 99
．． One rope hung over 64 lengths.

109, a set of weights 110 suspended from this, and a pulley 1 attached to 111160.52 supported around the disk 21 at a position 180 degrees symmetrical to the axis 54.42.
05.94, a rope 109 was pulled out from the disk 21 in the opposite direction in the Z-axis direction from the rope 109 that was hung on the pulley 99.64, and was hung across the pulley 9105.94.
It consists of a book rope 109 and a set of weights 110 suspended from it.

(III) The force transmission means for applying the load of Mz is the first
As shown in Fig. 4, the shafts 46, 47, 48, and 49 are attached to shafts 46, 47, 48, and 49 supported at intervals of 90 degrees around the disc 21 at the middle part of the disc 21 in the height direction. The pulleys 77.
It consists of four ropes 109 hung on 80, 83, and 86, and nine weights 110 suspended from each rope 109.

The force sensor evaluation and calibration jig of the above embodiment is used and operates as follows.

That is, as shown in FIG.
A weight 110 is suspended from the
In other words, the strain gauge 14.15.
Output is emitted from 16.17.

Also, as shown in the same FIG. 11, two ropes 109 are hung on pulleys 78 and 80 attached to the shaft 47
When a weight 110 is suspended from
．． Outputs are issued from 15.16.17.

Next, as shown in FIG. 12, a rope 109 is attached to the shaft 54.42 and hung on a gauge 99.64, and a rope 109 is hung on a pulley 100.70 attached to the shaft 55.44. and a rope 109 hanging from a gauge 105.67 attached to the shaft 58.45.
When a weight 110 is suspended from each of the four ropes, including the rope 109 hung on a pulley 101.73 attached to the shaft 56.45, and a load of Fz is applied thereto, for that load, Outputs are emitted from strain gauges 10-13.

Furthermore, as shown in FIG.
and a pulley 107.91 attached to the shaft 62.51.
When a weight 110 is suspended from each of two ropes, a rope 109 is hung on a rope 109, and a load of Mx is applied, there is a strain in response to the load.

Output is emitted from 11.15.

Next, as shown in the same FIG.
09, and a gauge 105. mounted on the shaft 60.52.
When a weight 110 is suspended from each of the two ropes, the rope 109 hung on the rope 94, and a load of My is applied,
An output is generated from the strain gauge 10.12 in response to that load.

In addition, as shown in FIG. 14, the shaft 46.47.4849
When a weight 110 is suspended from each of the four ropes 109 hung on a goreif 7.80.86.86 attached to the Outputs are emitted from gauges 14-17.

As mentioned above, in correspondence with the six elements of force and moment,
Since a load as an external force is applied to each force sensor 1 individually, the output appears only on the strain gauge corresponding to the load, and the output is small and does not appear on the other strain gauge as a result of crosstalk. . Therefore, the reliability of the strain gauge output is significantly improved.

The following equation holds between the output of the strain gauge and the load.

F=C0E ・・・・・・・・・・・・・・・
(1) However, F: Load vector E2 Output vector C: Conversion matrix Calibration of the force sensor 1 is performed by applying a load with a clear value to the force sensor 1 and measuring its output.

You can do this.

The output vector for the load vector is E=D, F
−・・・・・・・・・・・・・；・・・・・・・・・
...(4) However, D: Can be expressed as an inverse transformation matrix.

Here, the inverse transformation row and column are called a pseudo inverse matrix of the transformation matrix C, and the following relationship holds true in a pseudo manner.

D, C=I 109. −=−−−−−
-(6) D', D, C=Dt ・Song...Central concave song (7)
,−,C,=(D”,I)door ,1]1
... Yamakawa ... (8) However ■: Unit matrix J)": Transposed matrix of D Therefore, if we sequentially add six types of loads that are linearly independent of each other and whose values are clear, ,EI=D,Fi
・Curve・Curve・Concave curve (9) Here, Fi: The output vector corresponds to the first load vector Hl and Fl applied to the force sensor, and i=j
Regarding ~B, when the calculations for each row of the inverse transformation matrix are summarized, eight simultaneous equations with dj+~dj6 (j=1 to 8) as unknowns are obtained. That is, by solving each of these eight simultaneous equations, the coefficients for each row of the inverse transformation matrix can be found, and the transformation matrix C can be determined using equation (8). If,
The transformation matrix is as follows.

Here, if each of the components 1 to f6 of the load vector F can be applied independently to the force sensor, the equation (1
1) is as follows, and the coefficients can be easily found.

Fx = C+ (C5+ C6) +C2(C7-e
s ) Fy' = C1 (C7+ es ) + C2 (e
a-C5) Fz = -Cs (e++e2+es+e
a) Mx = Ca (C2+e4) My = -Ca (e++ez) Mz = C6 (C6-es-4-ea -e: )
Note that in the present invention, the holding means for the force sensor 1 is not limited to the illustrated embodiment.

Further, the force transmitting means to the force sensor 1 is not limited to the illustrated embodiment, but it is sufficient that the means can be separated into six elements of force and moment, and can individually apply a load as an external force.

〔Effect of the invention〕

According to the present invention described above, since external forces can be applied individually to the force sensor corresponding to the six elements of force and moment, it is possible to obtain a unique output through the strain gauge that does not include the force component. Therefore, there is no crosstalk of the calibration load, and crosstalk specific to the force sensor can be separated, which has the effect of allowing the force sensor to be accurately evaluated and calibrated.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the force sensor, Figure 2 is a diagram showing how the force sensor is attached to the robot, Figure 6 is a perspective view showing the position of attaching the strain gauge to the elastic beam of the force sensor, and Figure 4. 14 to 14 show one embodiment of the present invention, and the fourth embodiment of the present invention is shown in FIG.
The figure is a perspective view showing how the force sensor and force transmitting means are attached to the framework, FIG. 5 is a plan view of FIG. 4, and FIG. 6 is a perspective view showing how the force sensor holding means, disk, and framework are attached. 7, 8, and 9 are explanatory diagrams showing the state of cooperation between the members constituting the force transmitting means and the disc, and FIG. 10 is a partially enlarged longitudinal sectional front view, and FIG. Figure 11 is an enlarged front view showing an example of a weight with a force sensor equipped with Fx,
, F'y, FIG. 12 is a diagram showing a force transmitting means that applies a force of Fz to the force sensor, and FIG. 15 is a force transmitting means that applies a load of Mx, My to the force sensor. FIG. 14 is a diagram showing a force transmitting means for applying a load of Mz to a force sensor. 1... Force sensor 2-9... Elastic beams of the force sensor 10-17... Strain gauge of the force sensor 19... Block 20 constituting the holding means of the force sensor... Same M) , 21...A circular plate 26 attached to the force sensor...Framework 4 for attaching the force sensor, force transmission means, etc. to C9
2-62... Shafts 63-10 constituting force transmission means
7...Same pulley 109...Same rope 110...Same weight. Figure 1 Brown Figure 2/8% 3 Figure z Crow 4 Figure Complete 5 Flash Figure 6 Figure 7 Figure δ ? Flash 10th Figure 77/1z Hole 72nd Figure 0 (V3: Hesho-gata /3 Figure%/4M 203

Claims (1)

[Claims] 1. The force sensor is held constant by the holding means, and the force sensor is surrounded by a three-dimensional space corresponding to five elements of force and five elements of moment, a total of six elements. A jig for evaluating and calibrating a force sensor, characterized in that a force transmitting means is arranged so that an external force can be individually applied to each of the six elements via the force transmitting means. 2. The force transmission means is composed of a pulley attached to a shaft supported by a framework, a rope tied to a force sensor and hung on the pulley, and a weight suspended from the end of the rope. A jig for evaluating and calibrating a force sensor according to claim 1, characterized in that: