JP2009042042A - Sensor module and force sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor module whose upper limit of a measuring range is not restricted to the upper limit of a measuring range of a used pressure-sensitive type conductive sensor. <P>SOLUTION: This sensor module is equipped with a steel plate 17 pressed from the outside; the pressure-sensitive type conductive sensor 11 for detecting a conductivity change on a conductivity changing part corresponding to a force applied through the steel plate 17, which is a pressure-sensitive type conductive sensor 11 having the conductivity changing part whose conductivity is changed corresponding to an applied force; and an elastic member 12 for reducing a force applied to the pressure-sensitive type conductive sensor 11 in the pressing force from the outside, by receiving a part of a force applicable to the pressure-sensitive type conductive sensor 11 through the steel plate 17. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a force sensor that measures force or moment.

  Conventionally, as a force sensor for measuring force or moment, there is a force sensor using a strain gauge for detecting force.

In addition, there is a technology related to a pressure-sensitive conductivity sensor having a conductivity changing portion having a property that the conductivity changes according to an external pressure (see Patent Documents 1 to 4), and such a pressure-sensitive conductivity sensor. There is a technology related to a six-axis force sensor that measures translational force and moment using a sensor (see Patent Document 5).
JP 2001-093707 A JP 2006-184098 A Japanese Patent Laid-Open No. 10-0778357 Japanese Patent Laid-Open No. 54-057680 JP 2007-108079 A

  Conventionally, force sensors that use strain gauges to detect force are widely used as force sensors that measure force or moment. However, in the force sensor using the strain gauge, it is necessary to dispose the strain portion, so that a space for disposing the strain portion is required, and it is difficult to reduce the size of the sensor. Moreover, high processing accuracy is required for processing of the strained portion so that the relationship between the force acting on the strained portion and the generated strain is linear.

  Accordingly, the present invention relates to a six-axis force sensor that measures an external force using a pressure-sensitive conductivity sensor having a conductivity changing portion having a property of changing the conductivity according to an external pressure without using a strain gauge. The technology is disclosed (see Patent Document 5).

  The pressure-sensitive conductivity sensor is a sensor that detects a change in conductivity according to force by having a conductivity changing portion inside the sensor that changes in conductivity according to external pressure (see FIG. 18). ). The pressure-sensitive conductive sensor is connected to a measuring instrument with electrodes, and the measuring instrument calculates the pressure applied to the pressure-sensitive conductive sensor based on a voltage that varies depending on the conductivity. The pressure-sensitive conductive sensor has a pressure-sensitive surface, and a steel plate is bonded to the pressure-sensitive surface (sensing area) with a double-sided tape or an adhesive so as to be within the pressure-sensitive surface (see FIG. 19).

  When the force is measured using the pressure-sensitive conductive sensor having such a configuration, all the forces acting on the steel plate are loaded only on the pressure-sensitive surface of the sensor (see FIG. 20). For this reason, when measuring the force acting on the steel plate, it can measure up to the maximum load that can be measured by the sensor, but when a force exceeding the sensor performance is applied, the accuracy decreases, and the measurement becomes practically difficult. . In particular, commercially available pressure-sensitive conductive sensors have few variations, and there is a limit on the upper limit of the load that can be measured. For this reason, in the force sensor created using a commercially available pressure-sensitive conductive sensor as it is, the force that can be measured is limited.

  In view of the problems described above, an object of the present invention is to provide a sensor module in which the upper limit of the measurement range is not limited to the upper limit of the measurement range of the pressure-sensitive conductive sensor being used.

  In order to solve the above-described problems, the present invention provides a sensor module having a structure in which load-reducing means is provided and force is distributed to the load-relieving means and the pressure-sensitive conductive sensor. It is possible to provide a sensor module that is not limited to the upper limit of the measurement range of the pressure-sensitive conductive sensor being used.

  Specifically, the present invention has a pressed portion that is pressed from the outside and a conductivity changing portion that changes in conductivity according to the applied force, and that corresponds to the force that is applied via the pressed portion. By receiving a part of the force that can act on the pressure-sensitive conductivity sensor via the pressed portion and the pressure-sensitive conductivity sensor that detects a change in conductivity in the conductivity-changing portion, It is a sensor module provided with the load relief part which reduces the force which acts on the said pressure-sensitive conductivity sensor among the force of a press.

  Here, the sensor module is an element constituting a sensor for measuring the acting force, and is a device for measuring the force applied to the pressed portion. When using the sensor module, based on the sensor signal output from the pressure-sensitive conductive sensor, the force applied to the pressed portion is calculated by a computer or the like that has received the sensor signal.

  In the sensor module according to the present invention, when the sensor module includes the load-free portion, a force smaller than the force applied to the pressed portion, which is the actual measurement target force, is applied to the pressure-sensitive conductive sensor. . Since the actual measurement target force is calculated based on the change in conductivity according to the force smaller than the actual measurement target force, the sensor module according to the present invention uses the pressure sensitive type. A force exceeding the upper limit of the measurement range of the conductive sensor can be measured.

  In other words, since the load applied to the pressure-sensitive conductive sensor is reduced by the amount distributed to the load-carrying part, as a result, a load exceeding the upper limit of the measurement range of the pressure-sensitive conductive sensor may be applied to the sensor module. It becomes possible. According to the present invention, sensor modules having various measurement ranges can be manufactured by selecting a load-carrying portion in accordance with a target measurement load.

  In the present invention, the pressure-sensitive conductive sensor has a pressure-sensitive surface that receives the pressing force by being in contact with the pressed portion, and the load-relieving portion includes the pressure-sensitive portion of the pressed portion. It may have an elastic member that is compressed together with the pressure-sensitive conductive sensor when the pressed portion is pressed by being in contact with a portion where the pressure surface is not in contact.

  The load-carrying part is made of an elastic member, and the pressure-sensitive conductive sensor and the elastic member are compressed together. Without being obstructed, it is possible to spread the force and widen the upper limit of the measurement range.

  In the present invention, the pressure-sensitive surface of the pressed portion and the surface in contact with the elastic member are flat surfaces, and the elastic member has a surface in contact with the pressed portion around the pressure-sensitive conductive sensor. It may be provided so as to be on the same plane as the pressure sensitive surface.

  Since the surface that transmits the force to the pressure-sensitive conductive sensor and the surface that transmits the elastic member form the same plane, the force applied to the pressed part is evenly distributed, making it easy to obtain accurate measurement results. Is possible.

  Moreover, this invention is a force sensor provided with the some sensor module provided so that the change of the electrical conductivity according to the force to the some axial direction which did not mutually overlap was detected, respectively.

  According to the present invention, an appropriate sensor module is created according to the application (necessary measurement range) of the force sensor and incorporated into the force sensor, whereby a force sensor suitable for the application can be manufactured.

  In addition, for example, a sensor module according to the present invention is provided in a six-axis sensor for calculating a three-axis translational force and a moment around the three axes from the detected force, thereby using an existing pressure-sensitive conductive sensor. It is possible to manufacture a six-axis force sensor having an upper limit of the measurement range according to the application.

  According to the present invention, it is possible to provide a sensor module in which the upper limit of the measurement range is not limited to the upper limit of the measurement range of the pressure-sensitive conductive sensor being used.

  Embodiments of a sensor module and a force sensor according to the present invention will be described with reference to the drawings.

<Configuration of sensor module>
FIG. 1 is a schematic plan view showing the sensor module 10 in a state where the steel plate 17 is not attached, and FIG. 2 is a schematic plan view showing the sensor module 10 in a state where the steel plate 17 is attached in the present embodiment. is there. FIG. 3 is a schematic cross-sectional view of the sensor module 10 in the present embodiment. An elastic member 12 having the same thickness as the pressure-sensitive conductive sensor 11 is disposed around the pressure-sensitive conductive sensor 11 (see FIG. 3). Further, a steel plate 17 having a width greater than the pressure-sensitive surface 13 and corresponding to the pressed portion of the present invention (a steel plate having an arithmetic average roughness of 0.008 to 25 μm according to JIS B0601. In this embodiment, the arithmetic average roughness 1 .. 6 μm steel plate) is bonded to the pressure-sensitive surface 13 and the elastic member 12 so as to cover the pressure-sensitive surface 13 and the elastic member 12. The elastic member 12 and the pressure-sensitive conductive sensor 11 are bonded to the sensor mounting plate 14. In addition, the pressure-sensitive conductive sensor is connected to a measuring instrument with electrodes 15 and 16. In addition, the shape along the steel plate 17 may be sufficient as the elastic member 12 used for the sensor module 10 (refer the code | symbol 12b of FIG. 4). In the present embodiment, the elastic member 12 is PET (Polyethylene terephthalate). However, if the elastic member 12 has characteristics (eg, Young's modulus described later) required as a load-carrying means, other materials (for example, Polymer materials, rubber, metals, etc.) may be employed.

FIG. 5 is a diagram showing a configuration of the pressure-sensitive conductive sensor 11 in the present embodiment. The pressure-sensitive conductivity sensor 11 includes a polyester film layer on the outer surface, a copper ink or silver ink on the outer surface thereof, an electrode layer formed by screen printing on the polyester film layer using a screen printer, and further wrapped in the electrode layer. And a pressure-sensitive ink layer formed by screen-printing pressure-sensitive ink on the electrode layer. When a force W _f from the outside of the pressure-sensitive conductive sensor 11 is applied, the force is transmitted to the pressure-sensitive ink layer, and the conductivity (resistance value) changes. Therefore, this pressure-sensitive ink layer functions as a conductivity changing portion.

  Here, the force applied to the pressure-sensitive conductive sensor 11 is calculated by detecting the change in the conductivity of the pressure-sensitive ink layer. In calculating the force, it is preferable that there is a linear relative relationship between the change in conductivity of the pressure-sensitive ink layer and the force. The pressure-sensitive conductive sensor 11 used in the present embodiment preferably has a thickness of 0.05 mm or more and 5.0 mm or less in order to obtain high sensitivity and strength, and is 0.1 mm or more and 1.0 mm or less. More preferably, it has a thickness of

When exerting a force W _f to the steel plate 17 of such a sensor module 10, the force is also dispersed in the elastic member 12 as well as pressure-sensitive surface 13 of the pressure-sensitive conductive sensor 11. For this reason, the force acting on the pressure-sensitive surface 13 decreases by the amount dispersed in the elastic member 12 (see FIG. 3). As a result, it is possible to apply a force exceeding the upper limit of the original measurement range of the pressure-sensitive conductive sensor 11 to the steel plate 17 of the sensor module 10.

  That is, according to the sensor module 10 according to the present embodiment, even when a force exceeding the upper limit of the measurement range of the pressure-sensitive conductive sensor 11 is applied to the sensor module 10, the conductivity of the pressure-sensitive conductive sensor 11 can be measured. Therefore, the force actually applied to the sensor module 10 can be calculated from this conductivity.

<Measurement theory>
It is assumed that a force _Wf is applied to the steel plate 17 of the sensor module 10. At this time, when the force applied to the elastic member 12 is F _e and the force applied to the sensor pressure-sensitive surface 13 is F _s , the following equation is established.

なお、ここで、ｋ_eは弾性部材１２の剛性係数、ｋ_sはセンサ感圧面１３の剛性係数である。 FIG. 6 is a schematic cross-sectional view of the sensor module 10 in the present embodiment. In the following calculation, since the steel plate 17 is sufficiently hard as compared with the elastic member 12 and the sensor pressure-sensitive surface 13, it is assumed that it is a rigid body. As shown in FIG. 6, when a force W _f is applied to the steel plate 17, the steel plate 17 is not deformed, the thickness t of the elastic member 12 and the sensor sense pressure surface 13 is elastically deformed only force W _f direction Δx Then, the following equation holds.

Here, k _e is the stiffness coefficient of the elastic member 12, and k _s is the stiffness coefficient of the sensor pressure-sensitive surface 13.

FIG. 7 is a schematic plan view showing areas of the pressure-sensitive surface 13 and the elastic member 12 in the present embodiment. The Young's modulus of the elastic member 12 is E _e , the area where the steel plate 17 and the elastic member 12 are in contact (hereinafter referred to as “the area of the elastic member 12”) is A, and the Young's modulus of the pressure-sensitive conductive sensor 11 is the body. E _s, B an area of pressure-sensitive conductive sensor 11 body, the elastic member 12 and the pressure-sensitive conductive sensor 11 body thickness to t (see Figure 6), the stiffness coefficient of the elastic member 12 k _e and the sensor sense The stiffness coefficient k _s of the pressure surface 13 can be expressed by the following equation.

Here, when the equations (4) and (5) are substituted into the equations (2) and (3), the following equations are obtained.

Then, by substituting the equations (6) and (7) into the equation (1), the following equation is obtained.

That is, since the force W _f and the amount of elastic deformation Δx have a corresponding relationship, it is possible to calculate W _f from the conductivity that varies with Δx.

<Method for estimating Young's modulus of pressure-sensitive conductive sensor body>
Next, a method of estimating the pressure-sensitive conductive sensor 11 body of Young's modulus E _s. FIG. 8 is a diagram showing a method for measuring the relationship between the force and voltage acting on the pressure-sensitive conductive sensor 11 or the sensor module 10 using a load tester in the present embodiment. Screws with balls are attached to the moving parts of the load tester. Below the ball screw, a pressure-sensitive conductive sensor 11 for performing a test is attached to a mounting plate. The main part of the pressure-sensitive conductive sensor 11 is shown as a sensor in FIG. The attachment plate is attached to a force sensor (IFS-100M40A manufactured by Nitta Corporation) attached to a load tester. The movable part of the load tester moves up and down, and a force is applied to the pressure-sensitive conductive sensor 11 to be verified from the ball at the tip of the movable part through the steel plate. The applied force W _f is the force sensor IFS-100.
Measured by M40A.

  FIG. 9 is a diagram showing a system configuration for measuring the force applied to the pressure-sensitive conductive sensor 11 based on the sensor signal of the pressure-sensitive conductive sensor 11 in the present embodiment. The pressure-sensitive conductive sensor 11 to be tested is connected to a computer via an AD converter, and the computer is based on a sensor signal (voltage in this embodiment) output from the pressure-sensitive conductive sensor 11. The force applied to the conductive sensor 11 is measured.

First, a steel plate (a steel plate having the same size as the pressure-sensitive surface 13) is bonded to the pressure-sensitive surface 13 of the pressure-sensitive conductive sensor 11 with a double-sided tape to create a conventional sensor module (see FIGS. 19 and 20). Then, a force F _s (force acting on the pressure-sensitive surface 13) is applied to the steel sheet, and the output sensor signal (output voltage) is measured, and the following relational expression of force and voltage (output voltage as force) (Conversion formula) is obtained using the method of least squares.

Next, the same pressure-sensitive conductive sensor 11 as described above with the steel plate removed is used, and the elastic member 12 having a known Young's modulus E _e is used as the elastic member 12 of the sensor module 10 according to the present invention. The sensor module 10 is created. Next, when a force W _f is applied to the steel plate 17 of the sensor module 10, the force F _s acting on the sensor pressure-sensitive surface 13 can be obtained from the output voltage of the sensor using the equation (9). Then, the force F _e acting on the elastic member 12 can be obtained by using the following equation.

Here, from the equations (6) and (7), if Δx is eliminated and E _s is obtained, the following equation is obtained.

In the formula (11), E _e (Young's modulus of the elastic member 12), A (area of the elastic member 12),
B (area of the pressure sensitive surface 13) is known. Further, the force F _e acting on the force F _s and the elastic member 12 acting on the sensor sense pressure surface 13 is obtained by the above method. For this reason, the Young's modulus of the pressure-sensitive surface 13 can be calculated | required using Formula (11).

<Selection method of elastic member for measuring up to desired maximum measurement load>
Next, a method for selecting an elastic member for measuring up to a desired maximum measurement load will be described. Assuming that the desired maximum measurement load is W _max and the upper limit value of the load that can be measured by the pressure-sensitive conductive sensor 11 is W _lim , the following expression is derived from Expression (7).

Since the desired maximum measured load is W _max , when Δx when W _max acts is obtained from equation (8), the following equation is obtained.

より、

Then, from the equations (12B) and (13), the Young's modulus E _e of the elastic member 12 for measuring up to a desired maximum measurement load W _max is derived.

Than,

That is, when the elastic member 12 having a Young's modulus satisfying the formula (14B) is used, even if a desired maximum measurement load W _max acts on the steel plate 17 of the sensor module 10, the sensor pressure-sensitive surface 13 can measure the sensor. A load below the upper limit value W _lim of the load acts. For this reason, a desired maximum measurement load W _max can be measured.

<Method of measuring force using this module>
Next, a method for measuring force using the sensor module 10 according to the present embodiment will be described. The load W _f is applied to the steel plate 17 of the sensor module 10 in advance using a load tester as shown in FIG. 8, and the sensor signal (output voltage) obtained from the sensor / sensor circuit and the force sense The load obtained from the sensor IFS-100M40A is measured. And the relational expression which shows the relationship between the obtained sensor signal and a load is calculated | required using the least squares method.

  When the sensor signal (output voltage) is actually incorporated into a force sensor or the like and used, the output sensor signal (output voltage) is substituted into equation (15) to apply the force applied to the sensor module 10. Is calculated. In this embodiment, a relational expression based on the actual measurement result is prepared in advance, and the force is calculated using this relational expression. However, the relational expression is calculated using a map or the like indicating the relationship between the sensor signal and the load. Alternatively, the load information obtained from the pressure-sensitive conductive sensor 11 itself (that is, the load information calculated from the relationship between the sensor signal and the load in a state where no load relief means is used), the pressure-sensitive conductive sensor 11, The elastic member 12 may be calculated from the Young's modulus and area of the elastic member 12.

<Distribution of load on pressure-sensitive surface and load on elastic member>
Using the method of estimating the Young's modulus E _s of the pressure-sensitive conductive sensor 11 body, the Young's modulus E _s of the pressure-sensitive surface 13 of a commercially available pressure-sensitive conductive sensor (Nitta Co. Flexi Force button sensor A201-100) As a result, it was 617.6 [kgf / mm ² ]. The maximum measurement load of the pressure-sensitive conductive sensor 11 is W _lim = 440 N (≈44.9 kgf
). Moreover, since the pressure-sensitive surface 13 is a circle having a diameter of 9.5 mm, the area B of the pressure-sensitive surface 13 is 70.9 mm ² .

As an example, consider a case where a sensor module 10 that can measure up to a maximum load W _max = 700 N is manufactured using this sensor. Here, the adjustable elements are the Young's modulus E _e of the elastic member 12 and the area A of the elastic member 12 from the equation (14B).

となる。 When the steel plate 17 used for the sensor module 10 is a disk having a diameter of 16 mm and the center thereof is set to the center of the circular pressure-sensitive surface 13, the area A of the elastic member 12 is obtained as follows.
A = π (8) ² (area of the steel plate 17) −70.9 (area of the pressure sensitive surface 13) = 130.1 mm ²
Therefore, if the circular steel plate 17 having a diameter of 16 mm is used, the Young's modulus of the elastic member 12 necessary for creating the sensor module 10 having the maximum measurement load 700 N is obtained from the equation (14B):

It becomes.

From the formula (16), for example, PET having a Young's modulus of 282.3 [kgf / mm ² ] is formed from the elastic member 1.
2 can be selected.

A sensor module 10 using a circular steel plate 17 having a thickness of 1 mm and a diameter of 16 mm, a commercially available pressure-sensitive conductive sensor (Flexi Force button sensor A201-100 manufactured by Nitta Corporation) and a PET having a Young's modulus of 282.3 [kgf / mm ² ]. FIG. 10 shows the result of examining whether or not the load is distributed to the pressure-sensitive surface 13 and the elastic member 12 when a load is applied to the steel plate 17 of the sensor module 10. In FIG. 10, the vertical axis and the horizontal axis indicate the force applied to the sensor module 10, and the shaded portion of each bar graph indicates the force F _s acting on the sensor pressure-sensitive surface 13 (the output voltage from the sensor is substituted into equation (9)). The gray portion indicates the force F _e (= W _f −F _s ) acting on the elastic member 12. As shown in FIG.
Even when applied to 0, it can be seen that the force is distributed to the elastic member 12, and the sensor pressure-sensitive surface 13 is applied with a load of not more than the maximum measurement load 440N.

  This experimental result is measured to include the hysteresis of the conductive sensor (a phenomenon in which different signals are output from the sensor when the load is increased and when the load is decreased) After increasing the load by 100N from 100N to 700N, unloading is performed by 100N from 700N to 100N, and the force acting on the pressure-sensitive surface 13 is measured for each load. This is repeated 10 times, and the average value of 10 times of data is shown in FIG.

<Method of measuring force using sensor module>
Using the sensor module 10 manufactured in the above experiment, a load is applied to the steel plate 17 of the sensor module 10, and the output voltage and force are calculated from the voltage output from the sensor and the applied force data using the least square method. The relational expression (formula (15)) was obtained. Also in this experiment, in order to measure including the hysteresis of the conductive sensor, after increasing the load by 100N from 100N to 700N, unloading by 100N from 700N to 100N, and measuring for each load. 10 data were collected. FIG. 11 is a diagram showing the results of the experiment. In FIG. 11, the horizontal axis represents the force applied to the sensor module 10, and the vertical axis represents the force converted from the voltage value obtained from the sensor module 10 using the equation (15). For each force applied to the sensor module 10, the average value of the force data for 10 times obtained from the sensor module 10 is plotted with dots, and the error bar indicates the maximum value of the data for 10 times for each force. The minimum value is shown.

  From FIG. 11, it can be seen that the force applied to the sensor module 10 and the force output from the sensor module 10 are almost the same (the maximum error was ± 5% FS (% of error relative to full scale) or less). . The inventor of the present invention created eight similar sensor modules 10 and performed the same experiment. However, the same results were obtained for all eight sensor modules.

<6-axis force sensor using sensor module>
FIG. 12 is an exploded view showing a six-axis force sensor including the sensor module 10 according to the present embodiment, and FIG. 13 is a side view showing the six-axis force sensor including the sensor module 10 according to the present embodiment. The six-axis force sensor 1 is a sensor that can detect arbitrarily set translational forces in three axis directions orthogonal to each other and moments around the three axes. In the present embodiment, the three axes corresponding to the six-axis force sensor 1 are the X axis, the Y axis, and the Z axis, and these three axes are orthogonal to each other.

  The six-axis force sensor 1 includes an upper plate 2 that also functions as an action part to which an external force acts, a lower plate 3, and a translational force (± X direction) in a part of three axes corresponding to the six-axis force sensor 1. , ± Y direction and + Z direction translation force), and the other of the three axes in the remaining axial direction (−Z direction translation force) is electrically detected. A second detector 5. The upper plate 2 and the lower plate 3 are substantially the same type of plate materials, and are rectangular bodies in the present embodiment. The sides of the upper plate 2 and the lower plate 3 are set parallel to the X axis and the Y axis. Four first detection units 4 are provided at each corner of the upper plate 2 and the lower plate 3, and the second detection unit 5 is provided at the center of each side of the upper plate 2 and the lower plate 3.

  An electrical signal corresponding to the translational force detected by the first detection unit 4 and the second detection unit 5 is sent to the computer via the amplifier and the AD converter, and the translational force in the three-axis directions is calculated by the computation unit of the computer. And moments about the three axes are calculated (not shown).

  The first detection unit 4 is a sensor module 4a, 4b, 4c provided in the X-axis direction, the Y-axis direction, and the Z-axis direction, a spherical ball 4d, and a rectangular member fixed to the upper plate 2, respectively. The end face is composed of rods 4e and 4f parallel to the side of the upper plate 2 in the X-axis direction or Y-axis direction. Here, the sensor module 4 c corresponding to the Z-axis direction is directly provided on the lower plate 3, but the sensor modules 4 a and 4 b corresponding to the X-axis direction and the Y-axis direction are provided via a metal fitting 4 g provided on the lower plate 3. Provided.

  Here, the balls 4d are arranged so as to be in contact with the pressed parts of the sensor modules in the respective axial directions in each of the first detection parts 4 provided at the four corners of the lower plate 3. The size and shape of each component of the first detection unit 4 are such that the ball 4d in the first detection unit 4 contacts the pressed part of the sensor module in the three-axis directions of the corresponding X axis, Y axis, and Z axis. It is set. In the first detection unit 4, the ball 4 d is not fixed, but is restrained by the rods 4 e and 4 f, the sensor modules 4 a, 4 b and 4 c and the upper plate 2.

  The second detection unit 5 includes a lower unit 5 a fixed to the upper plate 2 and an upper unit 5 b fixed to the lower plate 3. The lower unit 5a includes a U-shaped metal fitting 5a1 and a screw 5a2 with a ball that is screwed into the center of the recess of the metal fitting 5a1 and has a spherical portion at the end. The upper unit 5b includes a metal fitting 5b1 having a concave shape and a sensor module 5b2 fixed to the concave portion of the metal fitting 5b1.

  Here, the upper unit 5b is fixed to the lower plate 3 so that the concave portion (the back portion of the U-shape) of the lower unit 5a and the concave portion of the upper unit 5b are combined. Then, the spherical portion of the ball screw 5a2 comes into contact with the sensor module 5b2. Therefore, the second detection unit 5 contacts the sensor module 5b2 of the upper unit 5b located on the minus side from the plus side via the spherical portion of the ball screw 5a2 in the Z-axis direction. The size and shape of each component of the second detection unit 5 are set so that the spherical portion of the ball screw in the second detection unit 5 contacts the pressed portion of the sensor module in the Z-axis direction. However, the lower unit 5a of the second detection unit 5 includes a U-shaped metal fitting 5a1, a hemispherical depression 5a4 provided in the center of the metal fitting 5a1, and a ball 5a3 inserted into the hemispherical depression 5a4. (See FIG. 14). In this case, when the recess of the lower unit 5a and the recess of the upper unit 5b are fixed to the lower plate 3 so as to be combined, the ball 5a3 makes point contact with the sensor module 5b2.

According to the six-axis force sensor according to the present embodiment, by using a sensor module in which the elastic member 12 or the steel plate 17 is appropriately selected by the above-described method in accordance with a desired maximum measurement load, a measurement range suitable for the application. A 6-axis force sensor having In particular, when this 6-axis force sensor is attached to the sole of a person and the floor reaction force acting on the sole and the point of action are measured (see FIG. 15), the vertical downward force is compared with other directions. Therefore, the upper limit of the measurement range of the pressure-sensitive conductive sensor that measures the force in the vertically downward direction is important.

  Therefore, the inventor of the present invention applied this sensor module to a force measurement unit in the vertically downward direction, and prototyped a 6-axis force sensor. Furthermore, using a load tester, the six-axis force sensor was fixed to the mounting plate, and an experiment was performed by applying a load to the upper plate of the prototype six-axis force sensor (see FIG. 16). The configuration of the load tester shown in FIG. 16 is substantially the same as that of the load tester shown in FIG.

  FIG. 17 is a diagram showing a representative example of the result of the above experiment. In FIG. 17, the horizontal axis represents time, and the vertical axis represents vertical downward force. In FIG. 17, the solid line indicates the force measured by using a 6-axis force sensor that was prototyped by incorporating this sensor module in the vertically downward force measuring unit. Moreover, the broken line has shown the force measured using force sensor IFS-100M40A. FIG. 17 shows that the force measured using the prototype 6-axis force sensor and the force measured using the force sensor IFS-100M40A substantially coincide. From this, it is considered that the present sensor module can be sufficiently applied to a six-axis force sensor.

It is a plane schematic diagram showing a sensor module in the state where a steel plate is not attached in an embodiment. It is a plane schematic diagram showing a sensor module in the state where a steel plate was attached in an embodiment. It is a section schematic diagram of a sensor module in an embodiment. It is a plane schematic diagram showing other embodiments of a sensor module in the state where a steel plate is not attached. It is a figure which shows the structure of the pressure-sensitive conductivity sensor in embodiment. It is a section schematic diagram of a sensor module in an embodiment. It is a plane schematic diagram showing the area of a pressure sensitive surface and an elastic member in an embodiment. In embodiment, it is a figure which shows the method of measuring the relationship between the force and voltage which act on a pressure-sensitive conductivity sensor or a sensor module using a load tester. In embodiment, it is a figure which shows the system configuration | structure for measuring the force applied to the pressure sensitive conductivity sensor based on the sensor signal of a pressure sensitive conductivity sensor. It is a figure which shows the result of having investigated whether the load is disperse | distributed to a pressure-sensitive surface and an elastic member, when a load is applied to the steel plate of the sensor module which concerns on embodiment. In embodiment, it is a figure which shows the experimental result which investigated the relationship between the force measured by the sensor module, and the force measured using force sensor IFS-100M40A. It is an exploded view showing a 6-axis force sensor provided with a sensor module concerning an embodiment. It is a side view showing a 6-axis force sensor provided with a sensor module concerning an embodiment. It is a figure which shows the variation of the 2nd detection part which concerns on embodiment. It is a figure which shows the application example of the 6-axis force sensor which concerns on embodiment. In embodiment, it is a figure which shows the method to test the 6 axis force sensor made as an experiment using a load tester. In an embodiment, it is a figure showing a typical example of a result of an experiment which tested a 6-axis force sensor made as an experiment using a load tester. It is a plane schematic diagram showing a pressure sensitive conductivity sensor in a state where a steel plate is not attached. It is the plane schematic which shows the conventional sensor module in the state where the steel plate was attached. It is a cross-sectional schematic diagram of a conventional sensor module.

Explanation of symbols

1 6-axis force sensor 10 Sensor module 11 Pressure-sensitive conductive sensor 12 Elastic member (unloading part)
13 Pressure-sensitive surface 14 Sensor mounting plate 17 Steel plate (pressed part)

Claims (4)

A pressed part that is pressed from the outside;
A pressure-sensitive conductive sensor having a conductivity changing portion whose conductivity changes in accordance with an applied force, and detecting a change in conductivity in the conductivity changing portion in accordance with the force applied via the pressed portion When,
By receiving a part of the force that can act on the pressure-sensitive conductive sensor through the pressed portion, the load can be reduced to reduce the force acting on the pressure-sensitive conductive sensor out of the external pressing force. And
A sensor module. The pressure-sensitive conductive sensor has a pressure-sensitive surface that receives the pressing force by contacting the pressed portion.
The load-carrying portion is in contact with a portion of the pressed portion that is not in contact with the pressure-sensitive surface, so that when the pressed portion is pressed, it is compressed together with the pressure-sensitive conductive sensor. Having a member,
The sensor module according to claim 1. The pressure-sensitive surface and the surface in contact with the elastic member in the pressed portion are flat surfaces,
The elastic member is provided around the pressure-sensitive conductive sensor such that a surface in contact with the pressed portion is on the same plane as the pressure-sensitive surface.
The sensor module according to claim 2.   The sensor module according to any one of claims 1 to 3, comprising a plurality of sensor modules provided so as to detect a change in conductivity according to a plurality of axial forces that do not overlap each other. Force sensor.

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