JP2011215000A - Tactile sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tactile sensor for measuring external force.SOLUTION: The tactile sensor for measuring external force, such as wind velocity, includes a first conductive member 11, a second conductive member 12 disposed at a prescribed interval to the first conductive member 11, an elastic member 13 including the first conductive member 11 inside, a tactile member 14 provided in the elastic member 13 to receive external force, and a detection unit for detecting the external force. The elastic member 13 is deformed by the external force received by the tactile member 14 and hence capacitance between the first and second conductive members 11, 12 is changed. The external force is detected based on the change in the capacitance.

Description

  The present invention relates to a tactile sensor, and more particularly to a tactile sensor for detecting an external force such as wind force and measuring an external force such as wind speed or wind pressure. Furthermore, the present invention relates to a tactile sensor that can detect the direction of an external force such as a wind direction.

  Conventionally, as this type of tactile sensor, for example, there is one described in Patent Document 1. FIG. 10 is a cross-sectional view of a conventional tactile sensor.

  As shown in FIG. 10, in a conventional tactile sensor 100, a piezoelectric element 101 such as a piezoelectric film and a vibrator 102 that oscillates at a constant frequency are integrally joined via an insulating member 103. The piezoelectric element 101 and the vibrator 102 are each sandwiched between a pair of electrodes.

  When an external force is applied to the conventional tactile sensor 100, the vibration of the vibrator 102 corresponding to the external force is transmitted to the piezoelectric element 101 and detected as a change in signal waveform. In this case, when a vertical external force is applied as a pressure sensation, the amplitude of the signal waveform changes. On the other hand, when a horizontal external force is applied as a slip sensation, the frequency of the signal waveform changes. When both external forces are applied, the signal waveform changes in both amplitude and frequency.

  As described above, according to the conventional tactile sensor 100, it is possible to simultaneously detect a pressure sense and a slip sense.

JP 2002-31574 A

  However, the conventional tactile sensor 100 uses the piezoelectric element 101, and there is a limit to increasing the sensitivity. That is, in order to detect an external force by the piezoelectric element, a relatively large external force is required.

  Thus, although the conventional tactile sensor 100 can detect an external force with respect to a relatively large external force, it is difficult to detect a relatively small external force such as wind power, and the value of the external force is also low. It is also difficult to measure.

In addition, the conventional tactile sensor has a problem that it cannot detect the direction of the external force.
The present invention has been made to solve the above-described problem, and an object thereof is to provide a tactile sensor that can detect an external force even with a relatively small external force such as wind power. Another object of the present invention is to provide a tactile sensor that can detect the direction of an external force.

  In order to solve the above problem, one aspect of the tactile sensor according to the present invention includes a first conductive member, a second conductive member disposed at a predetermined interval from the first conductive member, and the first conductive member. It has an elastic member provided inside, a tactile member provided on the elastic member for receiving an external force, and a detection unit for detecting the external force. The first conductive member is received by the tactile member. The position of the second conductive member is displaced by the deformation of the elastic member due to the external force, and the detection unit is changed by the displacement of the position of the first conductive member. The first conductive member and the second conductive member The external force is detected based on the electrostatic capacity between the two.

  In this manner, the elastic member is deformed by the external force received by the tactile member, so that the relative positional relationship between the first conductive member and the second conductive member in the elastic member changes. Thereby, the electrostatic capacitance between the first conductive member and the second conductive member changes, and an external force can be detected based on the change in the electrostatic capacitance.

  Furthermore, in one aspect of the tactile sensor according to the present invention, the detection unit includes a capacitance frequency conversion unit, a calculation unit including a capacitance calculation unit and an external force information calculation unit, and the capacitance frequency conversion unit includes the first A predetermined frequency signal depending on the capacitance between the one conductive member and the second conductive member is generated, and the capacitance calculation unit is based on the frequency signal generated by the capacitance frequency conversion unit, It is preferable that an electrostatic capacity value is calculated, and the external force information calculation unit calculates an information value related to the external force based on the electrostatic capacity value calculated by the capacitance calculation unit.

  Furthermore, in one aspect of the tactile sensor according to the present invention, the capacitance frequency conversion unit outputs an oscillator that outputs a signal having an oscillation frequency corresponding to the capacitance, and a signal having a reference oscillation frequency that is a reference oscillation frequency. The frequency signal generated by the capacitive frequency converter is a difference between the oscillation frequency of the signal output from the oscillator and the reference oscillation frequency of the signal output from the reference oscillator. A signal having a corresponding frequency is preferable.

  Furthermore, in one aspect of the tactile sensor according to the present invention, the elastic member preferably has a Young's modulus of 1 MPa to 100 MPa.

  Furthermore, in one aspect of the tactile sensor according to the present invention, the second conductive member includes at least a first electrode, a second electrode, a third electrode, a fourth electrode, and a ground electrode, and the first electrode It is preferable that the second electrode and the second electrode are disposed to face each other with the ground electrode interposed therebetween, and the third electrode and the fourth electrode are disposed to face each other with the ground electrode interposed therebetween.

  Furthermore, in one aspect of the tactile sensor according to the present invention, the first conductive member is preferably made of metal powder.

  Furthermore, in one aspect of the tactile sensor according to the present invention, the tactile member is preferably composed of a linear member.

  The tactile sensor according to the present invention can detect an external force such as wind force and measure an external force such as wind speed or wind pressure.

1 is an external perspective view of a tactile sensor according to a first embodiment of the present invention. It is a figure which shows the operation principle of the tactile sensor which concerns on the 1st Embodiment of this invention. 1 is a block diagram of a tactile sensor according to a first embodiment of the present invention. It is an external appearance perspective view of the tactile sensor which concerns on the 2nd Embodiment of this invention. It is a top view of the electrode which constitutes the 2nd electric conduction member in the tactile sensor concerning a 2nd embodiment of the present invention. It is a block diagram of a tactile sensor according to a second embodiment of the present invention. The known correlation data regarding the change value of a wind speed and an electrostatic capacitance in the tactile sensor according to the second embodiment of the present invention is shown. It is a figure which shows operation | movement of the tactile sensor which concerns on the 2nd Embodiment of this invention. It is an external view of the tactile sensor which concerns on the modification of this invention. It is the elements on larger scale of the tactile sensor which concerns on the modification of this invention. It is sectional drawing of the conventional tactile sensor.

  Hereinafter, tactile sensors according to embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
First, a tactile sensor according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is an external perspective view of a tactile sensor according to a first embodiment of the present invention.

  As shown in FIG. 1, the tactile sensor 1 according to the first embodiment of the present invention is an artificial tactile sensor, and includes a first conductive member 11, a second conductive member 12, an elastic member 13, and a tactile member 14. The capacitance detection unit 10 is provided. Moreover, the tactile sensor 1 according to the present embodiment includes a detection unit 15 having a capacity frequency conversion unit 20 and a calculation unit 30 described later.

  The first conductive member 11 is composed of a rectangular metal electrode and is embedded in the elastic member 13. The first conductive member 11 is fixed inside the elastic member 13, but its position is displaced as the elastic member 13 is deformed.

  In the present embodiment, a gold foil is used as the first conductive member 11. In addition, as the material of the first conductive member 11, a conductive paint such as metal powder can be used. Further, the shape of the first conductive member 11 is not limited to a thin film shape such as a gold foil, but may be a plate-like body such as a metal plate.

  The second conductive member 12 is disposed at a predetermined interval from the first conductive member 11 and is formed on the detection unit 15 as a fixed electrode. An elastic member 13 is provided on the second conductive member 12. Even if the elastic member 13 is deformed, the position of the second conductive member 12 is basically not displaced.

  The first conductive member 11 and the second conductive member 12 form a capacitor with the elastic member 13 existing between them as a dielectric, and a predetermined gap is formed between the first conductive member 11 and the second conductive member 12. There is a capacitance of.

  In the present embodiment, aluminum is used as the material of the second conductive member 12. In the present embodiment, the first conductive member 11 and the second conductive member 12 are arranged in parallel, and the distance between the first conductive member 11 and the second conductive member 12 is 0.5 mm.

  The elastic member 13 is configured by a cylindrical body, and includes the first conductive member 11 therein. The first conductive member 11 inside the elastic member 13 is disposed at substantially the center of the elastic member 13 so that its main surface is substantially parallel to the bottom surface of the elastic member 13. The second conductive member 12 is provided on the bottom surface of the elastic member 13.

  The elastic member 13 is made of a material having a low Young's modulus. In this embodiment, a silicone rubber having a Young's modulus of 2.0 MPa is used. In this embodiment, it is preferable to use a material having a low Young's modulus with a Young's modulus of 1 MPa to 100 MPa as the material of the elastic member 13. By using such a low Young's modulus material as the material of the elastic member 13, even if the external force received by the tactile member 14 is relatively small, the external force transmitted from the tactile member 14 is affected by the external force. It is possible to obtain deformation of the elastic member 13 that can detect the above.

  Note that the shape of the elastic member 13 is not limited to a cylindrical body, and a hemisphere, a rectangular parallelepiped, a cube, or any other shape that is easy to manufacture can be appropriately employed.

  The tactile member 14 includes a thin disk-like base 14 a and linear tactile hairs 14 b erected at the center of the base, and is provided on the upper surface of the elastic member 13. The base 14a and the tactile hair 14b are made of a rigid material, and graphite is used in this embodiment. The tactile hair 14b is for directly receiving an external force (a force acting from the outside). When the tactile hair 14b receives an external force, the external force is transmitted to the elastic member 13, whereby the elastic member 13 is deformed.

  In the present embodiment, the tactile hair 14b is provided via the base 14a. However, the tactile hair 14b may be provided directly on the elastic member 13 without using the base 14a.

  The detection unit 15 is an integrated circuit including a predetermined circuit element. As described above, the second conductive member 12 is provided on the detection unit 15. In this embodiment, a 2.5 mm square LSI chip is used as the integrated circuit.

  Next, the operation principle of the tactile sensor according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a diagram illustrating an operation principle of the tactile sensor according to the first embodiment of the present invention.

  As shown in FIG. 2, when an external force such as wind power is received by the tactile hair 14b, the external force is transmitted to the elastic member 13, and the elastic member 13 is thereby deformed. As the elastic member 13 is deformed, the position of the first conductive member 11 embedded in the elastic member 13 is displaced.

  As a result, the position of the first conductive member 11 with respect to the second conductive member 12 is displaced. That is, the relative positional relationship between the first conductive member 11 and the second conductive member 12 changes. As a result, the capacitance between the first conductive member 11 and the second conductive member 12 changes. An external force can be detected by detecting this change in capacitance by the detection unit 15.

  Next, a method for measuring an external force with the tactile sensor according to the first embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram of the tactile sensor according to the first embodiment of the present invention.

  As shown in FIG. 3, the tactile sensor 1 according to the first embodiment of the present invention includes a capacitance detection unit 10, a capacitance frequency conversion unit 20, and a calculation unit 30.

  The capacitance detection unit 10 includes the components shown in FIG. 1, and the capacitance detection unit 10 detects the capacitance between the first conductive member 11 and the second conductive member 12.

  The capacitance frequency conversion unit 20 has a function of generating a predetermined frequency signal depending on the capacitance between the first conductive member 11 and the second conductive member 12, and as shown in FIG. , A reference oscillator 22, a mixer 23, a filter 24, and a counter 25.

The first oscillator 21 is connected to the second conductive member 12 and outputs a signal having a first oscillation frequency f ₁ that is an oscillation frequency corresponding to the capacitance detected by the capacitance detection unit 10. When the capacitance changes, the first oscillation frequency f ₁ also changes. In the present embodiment, a ring oscillator is used as the first oscillator 21.

The reference oscillator 22 outputs a signal having a reference oscillation frequency f _ref that is a constant oscillation frequency (fixed frequency) serving as a reference. In the present embodiment, a ring oscillator is used as the reference oscillator 22.

The mixer 23 receives the signal oscillated at the first oscillation frequency f ₁ from the first oscillator 21 and the signal oscillated at the reference oscillation frequency f _ref from the reference oscillator 22, thereby performing multiplication processing. ₁ , f _ref , f ₁ −f _ref , f ₁ + f _ref , 2f ₁ , 2f _ref frequency signals are output.

The filter 24 is an LPF (Low Pass Filter) that removes a high-frequency signal component. The filter 24 removes the signals of f ₁ , f _ref , f ₁ + f _ref , 2f ₁ , 2f _ref from the signal from the mixer 23, and generates the first oscillation frequency f ₁ and the reference oscillation frequency f _ref . Only the signal of f ₁ −f _ref which is the frequency of the difference is output.

The counter 25 counts the frequency of the signal having the frequency f ₁ −f _ref from the filter 24, and calculates a count value per unit time, that is, a frequency f ₁ −f _ref per unit time in decimal. This is a frequency counter that generates a frequency signal. The calculated frequency signal is output to the calculation unit 30.

  Moreover, the calculating part 30 is provided with the capacity | capacitance calculation part 31, the external force information calculation part 32, and the memory 33, as shown in FIG.

  The capacity calculation unit 31 receives the frequency signal generated by the counter 25 and calculates a capacitance value based on the frequency signal. The value of the electrostatic capacity is a change value (ΔC) of the electrostatic capacity that has changed with the change in the relative positional relationship between the first conductive member 11 and the second conductive member 12. The calculated capacitance value is output to the external force information calculation unit 32.

  The external force information calculation unit 32 calculates the value of external force information, which is information related to the external force, based on the capacitance value calculated by the capacitance calculation unit 31. The external force information includes, for example, wind pressure or wind speed when the external force is wind power. The value of the external force information can be calculated by referring to known correlation data indicating the correlation between the external force information and the capacitance with respect to the actually calculated capacitance.

  For example, when the external force information to be calculated is the wind speed, correlation data between the wind speed and the capacitance change value (increase / decrease value) is created in advance, and the capacitance change value calculated by actually measuring the correlation data. Thus, the actually measured wind speed can be calculated. The known correlation data is stored in the memory 33.

  In the present embodiment, the capacitance frequency conversion unit 20 and the calculation unit 30 are provided in the detection unit 15 configured by an LSI chip. Each component of the capacity frequency conversion unit 20 and the calculation unit 30 is configured by a predetermined circuit element in the LSI chip. The LSI chip is provided with other necessary peripheral circuits.

Next, a method for manufacturing the tactile sensor according to the present embodiment will be described.
First, a thin film is formed using a material such as silicone rubber. The thin film can be produced by dissolving the material in a solvent, spreading it thin and drying it.

  Next, a gold foil is placed on the thin film as the first conductive member 11. And the thin film, such as the same silicone rubber, is mounted on it, and both thin films are welded. Thereby, the elastic member 13 in which the first conductive member 11 is embedded can be formed.

  Thereafter, the tactile hair made of wire or the like is fixed on the elastic member 13 so as not to tilt.

  Next, an LSI chip having the functions of the capacitance frequency conversion unit 20 and the calculation unit 30 and having the second conductive member 12 formed on the upper surface is prepared in advance, and the first conductive member is connected to the second conductive member 12 of the LSI chip. The elastic member 13 provided with the first conductive member 11 and the tactile member 14 is mounted on the LSI chip so that the member 11 faces.

Thereby, the tactile sensor according to the present embodiment can be manufactured.
As described above, the tactile sensor 1 according to the first embodiment of the present invention includes the capacitance frequency conversion unit 20 and the calculation unit 30 in addition to the capacitance detection unit 10, thereby not only detecting external force but also external force information. It can be used as a pressure sensor that can calculate the value of. Moreover, in this embodiment, frequency is used as a method for detecting a change in capacitance. As a result, errors are less likely to occur during signal transmission, and a pressure sensor with high measurement accuracy can be realized.

(Second Embodiment)
Next, a tactile sensor according to a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is an external perspective view of a tactile sensor according to a second embodiment of the present invention. In FIG. 4, the same components as those in the first embodiment of the present invention in FIG. 1 are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  In FIG. 4, the tactile sensor 2 according to the second embodiment of the present invention is different from the tactile sensor according to the first embodiment of the present invention in the configuration of the second conductive member 12.

  The tactile sensor 2 according to the second embodiment of the present invention is a tactile sensor that can detect the direction of an external force, and as shown in FIG. The conductive member 12 includes a first electrode 12a, a second electrode 12b, a third electrode 12c, a fourth electrode 12d, and a ground electrode 12GND. As shown in FIG. 4, the area of the entire electrode region where the second conductive member 12 is formed is preferably smaller than the area of the first conductive member 11.

  The electrode configuration of the second conductive member 12 will be described in detail with reference to FIG. FIG. 5 is a plan view of the electrode region of the second conductive member in the tactile sensor according to the second embodiment of the present invention.

  As shown in FIG. 5, the second conductive member 12 according to the present embodiment includes a first electrode 12a, a second electrode 12b, and a third electrode 12c with the ground electrode 12GND as the center in a square electrode region indicated by a dotted line. The fourth electrode 12d is arranged point-symmetrically.

  The ground electrode 12GND is connected to the ground wiring of the integrated circuit so as to prevent the first conductive member 11 from being electrically floated, and has a ground potential.

  The first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d are disposed around the ground electrode 12GND. The first electrode 12a and the second electrode 12b are disposed to face each other with the ground electrode 12GND interposed therebetween in the horizontal direction of the drawing. The third electrode 12c and the fourth electrode 12d are opposed to each other with the ground electrode 12GND interposed therebetween in the vertical direction of the drawing. The first electrode 12a to the fourth electrode 12d are formed so that the inner sides thereof conform to the outer shape of the ground electrode 12GND.

  In the present embodiment, the gap between the electrodes is configured to be 300 μm. As described above, each of the first electrode 12a to the fourth electrode 12d is connected to the oscillator in the integrated circuit.

  Thus, in the present embodiment, the first electrode 12a to the fourth electrode 12d are arranged in four directions indicated by two orthogonal straight lines with the ground electrode 12GND as the center. That is, the straight line connecting the center of the first electrode 12a and the center of the second electrode 12b is orthogonal to the straight line connecting the center of the third electrode 12c and the center of the fourth electrode 12d, and the intersection is the center of the ground electrode 12GND. It is configured to pass.

  In order to improve the sensitivity of the sensor, the area ratio between the ground electrode 12GND and the first electrode 12a to the fourth electrode 12d should be set so that the amount of change in capacitance when viewed from the oscillator is maximized. Is preferred. That is, it is preferable to set the frequency change of the oscillator to be the largest.

  Next, the overall configuration of the tactile sensor 2 according to the second embodiment of the present invention will be described. FIG. 6 is a block diagram of a tactile sensor according to a second embodiment of the present invention. In FIG. 6, the same components as those in the first embodiment of the present invention in FIG. 3 are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  As shown in FIG. 6, the tactile sensor 2 according to the present embodiment includes a capacitance detection unit 10, a capacitance frequency conversion unit 20, and a calculation unit 30.

  The capacitance detection unit 10 includes the components shown in FIG. 5, and the capacitance between the first conductive member 11 and the second conductive member 12 is detected by the capacitance detection unit 10. In the present embodiment, the first electrode 12a to the fourth electrode 12d in the second conductive member 12 are each connected to an oscillator. Therefore, the electrostatic capacitance between each electrode of the first electrode 12a to the fourth electrode 12d and the first conductive member 11 can be detected independently.

  The capacitance frequency conversion unit 20 has a function of generating a predetermined frequency signal depending on the capacitance with respect to each electrode of the second conductive member 12, and as shown in FIG. 6, the first oscillator 21a and the second oscillator 21b. , Four oscillators of a third oscillator 21c and a fourth oscillator 21d, and one reference oscillator 22.

  The capacitive frequency converter 20 includes a first mixer 23a, a second mixer 23b, a third mixer 23c, and a fourth mixer 23d connected to each of the four oscillators, and further includes a filter 24 and a counter 25.

The first oscillator 21a is connected to the first electrode 12a, and has an oscillation frequency corresponding to the capacitance between the first conductive member 11 and the first electrode 12a, as in the first embodiment. A signal having the first oscillation frequency f ₁ is oscillated and output.

The second oscillator 21b is connected to the second electrode 12b, a second signal of the oscillation frequency f ₂ is an oscillation frequency corresponding to the electrostatic capacitance between the first conductive member 11 and the second electrode 12b output To do.

The third oscillator 21c is connected to the third electrode 12c, a third signal of the oscillation frequency f ₃ is an oscillation frequency corresponding to the electrostatic capacitance between the first conductive member 11 and the third electrode 12c outputs To do.

The fourth oscillator 21d is connected to the fourth electrode 12d, a signal of the fourth oscillation frequency f ₄ is an oscillation frequency corresponding to the electrostatic capacitance between the first conductive member 11 and the fourth electrode 12d outputs To do.

As in the first embodiment, the reference oscillator 22 oscillates and outputs a signal having a reference oscillation frequency f _ref that is a constant oscillation frequency (fixed frequency) serving as a reference.

  In the present embodiment, a ring oscillator is used as the first oscillator 21a to the fourth oscillator 21d and the reference oscillator 22 described above.

The first mixer 23a is a signal oscillated by the first oscillator frequency f ₁ from the first oscillator 21a, a signal oscillated by the reference oscillation frequency f _ref from the reference oscillator 22 is input. Thus, multiplication processing is performed, and signals having frequencies of f ₁ , f _ref , f ₁ −f _ref , f ₁ + f _ref , 2f ₁ , and 2f _ref are output.

Similarly, the second mixer 23b, the third mixer 23c, and the fourth mixer 23d respectively multiply the signal of the frequencies f _{2 to} f _{4 and} the signal of the reference oscillation frequency f _ref to obtain f ₂ −f _ref , A signal having a frequency such as f ₃ -f _ref or f ₄ -f _ref is output.

The filter 24 is an LPF that removes a high-frequency signal component, as in the first embodiment. The filter 24 removes signals other than f ₁ −f _ref , f ₂ −f _ref , f ₃ −f _ref, and f ₄ −f _ref from the signals from the first mixer 23 a to the fourth mixer 23 d. , F ₁ −f _ref , f ₂ −f _ref , f ₃ −f _ref and f ₄ −f _ref only.

The counter 25 counts the frequency of the signal of the frequency f ₁ −f _ref , f ₂ −f _ref , f ₃ −f _ref, or f ₄ −f _ref from the filter 24, and counts per unit time. A frequency counter that generates a value. That is, the counter 25 calculates the first to fourth frequency signals obtained by calculating the frequency per unit time f ₁ −f _ref , f ₂ −f _ref , f ₃ −f _ref, or f ₄ −f _ref in decimal. Generate. The calculated first to fourth frequency signals are output to the arithmetic unit 30.

  As illustrated in FIG. 6, the calculation unit 30 includes a capacity calculation unit 31, an external force information calculation unit 32, and a memory 33, as in the first embodiment. Since the function of each component of the calculation unit 30 is the same as that of the first embodiment, detailed description thereof is omitted. The capacitance calculation unit calculates the capacitance value for each of the first to fourth frequency signals, and the external force information calculation unit calculates the external force information value based on the capacitance value.

  For calculation of the value of the external force information, refer to the known correlation data in which the correlation between the external force information and the capacitance is shown with respect to the actually calculated capacitance as in the first embodiment. Can be done by.

Specifically, capacitance displacements ΔC _X , ΔC in the X-axis direction, the Y-axis direction, and the Z-axis direction are determined from the capacitances of the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d. _Y, and calculates the [Delta] C _Z, capacitance displacement ΔC _X, ΔC _Y, ΔC _Z respectively and the external force data (e.g., stress sigma) by reference to known correlation data correlation has been shown between, X-axis direction , External force information in the Y-axis direction and Z-axis direction (for example, stress components σ _X , σ _Y , and σ _{Z in} the X-axis direction, Y-axis direction, and Z-axis direction) can be calculated.

  This known correlation data will be described with reference to FIG. FIG. 7 shows known correlation data regarding the change in wind speed and capacitance in the tactile sensor according to the second embodiment of the present invention. In the present embodiment, the known correlation data regarding the wind speed and the change value of the capacitance is a quadratic curve as shown in FIG.

  For example, in the present embodiment, the known correlation data is calculated by setting the conditions of each component constituting the tactile sensor as follows.

The electric field region of the first conductive member 11 and the second conductive member 12 was a square having a side length of 1.0 mm. The distance between the first conductive member 11 and the second conductive member 12 was 0.5 mm. The ratio of the ground electrode 12GND in the second conductive member 12 to the entire electric field region of the second conductive member 12 was 0.46. The elastic member 13 had a Young's modulus of 2 MPa and a relative dielectric constant of 2. The elastic member 13 was a cylinder having a height of 1.0 mm and a diameter of 2.0 mm. The tactile hair 14b was a cylinder having a length of 10.0 mm and a diameter of 1.0 mm. The vacuum dielectric constant was 8.85 × 10 ⁻¹² , the air density was 1.293 kg / cm ^3, and the air resistance received by the elastic member 13 was 0.7.

  The change in capacitance with respect to the wind speed calculated under the above conditions is as shown in Table 1 below.

  By plotting the results in Table 1, the correlation data shown in FIG. 7 can be created.

  The capacitance change value (ΔC) calculated by the capacity calculation unit 31 can be converted into the wind speed based on the correlation data of the quadratic curve shown in FIG.

  Next, the operation of the tactile sensor according to this embodiment configured as described above will be described with reference to FIG. FIG. 8 is a diagram illustrating the operation of the tactile sensor according to the second embodiment of the present invention.

  As shown in FIG. 8, when an external force such as wind power is received by the tactile hair 14b, the external force is transmitted to the elastic member 13, and the elastic member 13 is deformed thereby. As the elastic member 13 is deformed, the position of the first conductive member 11 is displaced. As a result, the relative positional relationship between the first conductive member 11 and the second conductive member 12 changes.

  In this case, in the present embodiment, the second conductive member 12 is configured by the first electrode 12a to the fourth electrode 12d arranged in four directions of two straight lines orthogonal to each other. The electrostatic capacitance between the electrode 12a to the fourth electrode 12d changes. In the present embodiment, the direction of the external force can be specified by detecting the four capacitance changes by the detection unit 15.

  For example, if the elastic member 13 is deformed as shown in FIG. 8, since the distance between the first conductive member 11 and the first electrode 12a is increased, the first conductive member 11 and the first electrode 12a The capacitance during is reduced. On the other hand, since the distance between the first conductive member 11 and the second electrode 12b decreases, the capacitance between the first conductive member 11 and the second electrode 12b increases.

  Therefore, by calculating the change in capacitance, it can be detected that an external force is acting from the first electrode 12a toward the second electrode 12b. For example, when the external force is wind power, the wind direction can be measured.

  As described above, the tactile sensor 2 according to the second embodiment of the present invention is used as a stress sensor that can not only calculate the external force value of the scalar amount but also measure the vector amount indicating the direction of the external force. be able to. In addition, in the present embodiment, as in the first embodiment, since the frequency is used as a method for detecting the change in capacitance, a stress sensor with high measurement accuracy can be realized.

  If it is desired to detect only the direction of the external force such as the wind direction, it is not necessary to calculate the capacitance value itself relating to the first electrode 12a to the fourth electrode 12d, and the four values relating to the first electrode 12a to the fourth electrode 12d are not calculated. Only the relative balance change of the capacitance needs to be detected.

  When detecting the direction of external force such as the wind direction, the tactile hair 14b is preferably a member having a circular cross section such as a linear member. Thereby, the direction of the external force can be accurately transmitted to the elastic member 13, and the direction is accurately transmitted as the displacement of the position of the first conductive member 11. For example, if the tactile hair 14b is a plate-like body, stress concentrates in the direction perpendicular to the main surface of the plate-like body, and the directivity sensitivity becomes worse. On the other hand, by making the tactile hair 14b a member having a circular cross section such as a linear member, directivity can be given evenly in all directions of 360 degrees.

  For the same reason, the elastic member 13 is preferably a member having a circular cross section, and a cylindrical body is preferably used as in this embodiment. Thereby, the direction of the external force received by the elastic member 13 can be accurately transmitted to the first conductive member 11.

  In this embodiment, the external force information is calculated based on known correlation data indicating the correlation between the external force information and the capacitance, but the external force information is also calculated using the following mathematical formula. Can do. Hereinafter, the calculation method will be described in detail.

First, the capacitances of the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d are C _a , C _b , C _c , and C _d , respectively, and an external force is applied to the elastic member 13. If the capacitance in the absence is C ₀ , the following equation is established.

C _a = C ₀ + ΔC _a
C _b = C ₀ + ΔC _b
C _c = C ₀ + ΔC _c
C _d = C ₀ + ΔC _d

Further, the oscillation frequencies of the oscillators connected to the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d are set to f _a , f _b , f _c , and f _d , respectively, and an elastic member Assuming that the oscillation frequency in a state where no external force is applied to 13 is f ₀ , the following equation is established.

Δf _X = f _b −f _a
Δf _Y = f _c −f _d
Δf _Z = (f _a + f _b + f _c + f _d ) / 4-f ₀

Here, Δf _X , Δf _Y , and Δf _Z represent frequency displacements in the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively.

  Further, the relationship between the oscillation frequency of the oscillator and the capacitance can be expressed by the following equation.

f = K _osc × C ₀ ^-n (1 + ΔC / C ₀ ) ^-n
≒ K _osc × C ₀ ^-n (1-n × ΔC / C ₀ )

Here, K _osc is a capacitance frequency conversion gain, and is determined by a circuit constant. Further, n is determined by the operating mechanism of the oscillator, and n = 0.5 in the case of the LC tank circuit, and n = 1 in the case of the ring oscillator.

Therefore, the relationship between the frequency displacement in the three-axis direction and the capacitance can be expressed as follows. First, the frequency displacement Δf _X in the X-axis direction can be expressed by the following equation.

f _X = f _b −f _a
≒ K _osc × C _0- ^{(n + 1)} × n × (−ΔC _b + ΔC _a )

Here, assuming that ΔC _a = ΔC _Z −ΔC _X and ΔC _b = ΔC _Z + ΔC _X , the above f _X is approximated by the following equation.

f _X ≈-2K _osc × C _0- ^{(n + 1)} × n × (ΔC _X )

Similarly, if ΔC _d = ΔC _Z −ΔC _Y and ΔC _c = ΔC _Z + ΔC _Y , the frequency displacements Δf _Y and Δf _Z in the Y direction and the Z-axis direction can be approximated by the following equations.

f _Y = f _c −f _d
≒ K _osc × C _0- ^{(n + 1)} × n × (−ΔC _c + ΔC _d )
≒ -2K _osc × C _0- ^{(n + 1)} × n × (ΔC _Y )
f _Z ≈−K _osc × C _0- ^{(n + 1)} × n × (ΔC _Z )

Next, the relationship between frequency displacement and stress will be described.
First, the capacitance C of the electrode can be expressed by the following equation, where ε is the dielectric constant between the electrodes, S is the electrode area, and ΔZ is the change in the electrode spacing due to stress.

C = C ₀ + ΔC
= Ε × S × (1 / (Z + ΔZ))
≈ε × S × (1 / Z) × (1−ΔZ)
= C ₀ (1-ΔZ)

  Therefore, ΔC can be expressed as:

ΔC ≒ −C ₀ × ΔZ

In the present embodiment, the stress applied to the elastic member 13 and sigma, when the compliance of the elastic member 13 and the C _P, [Delta] Z can be expressed by the following equation.

ΔZ = −Z × C _P × σ

  Therefore, the capacitance displacement ΔC can be expressed by the following equation.

ΔC = −C ₀ × ΔZ
= −ε × S × (1 / Z) × ΔZ
= −ε × S × (1 / Z) × (−Z × C _P × σ)
= Ε × S × C _P × σ

Here, X-axis direction component of the stress sigma, Y-axis direction component and the Z-axis direction component, respectively σ _X, σ _Y, σ is _Z, the capacitance change [Delta] C for sigma _{X X,} sigma capacitance change with respect to _Y ΔC _{Y, σ Z} Assuming that the capacity changes ΔC _{Z with} respect to are independent and proportional to σ _X , σ _Y , and σ _Z , respectively, the capacity changes ΔC _X , ΔC _Y , and ΔC _Z can be expressed as follows.

ΔC _X ≒ ε × S × C _PX × σ _X
ΔC _Y ≒ ε × S × C _PY × σ _Y
ΔC _Z ≒ ε × S × C _PZ × σ _Z

  When this equation is transformed, it can be expressed as follows.

σ _X ≈ΔC _X / (ε × S × C _PX )
σ _Y ≈ΔC _Y / (ε × S × C _PY )
σ _Z ≈ΔC _Z / (ε × S × C _PZ )

  Here, when the relational expression between the frequency displacement and the capacitance described above is modified, it can be expressed as follows.

ΔC _X = −Δf _X / (2 × K _OSC × C _0- ^{(n + 1)} × n)
ΔC _Y = −Δf _Y / (2 × K _OSC × C _0- ^{(n + 1)} × n)
ΔC _Z = −Δf _X / (K _OSC × C _0- ^{(n + 1)} × n)

Substituting this into the above equation, σ _X , σ _Y , and σ _Z can be expressed as follows.

σ _X = −Δf _X / (2 × K _OSC × C _0- ^{(n + 1)} × n × ε × S × C _PX )
σ _Y = −Δf _Y / (2 × K _OSC × C _0- ^{(n + 1)} × n × ε × S × C _PY )
σ _Z = −Δf _Z / (K _OSC × C _0- ^{(n + 1)} × n × ε × S × C _PZ )

In this way, the relationship between the frequency change and the stress can be expressed by a mathematical expression.
In the above relational expression, K _OSC , f ₀ , and n are determined by circuit design. C ₀ and S are determined by the shape of the electrode. Further, ε, C _PX , C _PY and C _PZ are determined by the constituent materials.

As described above, by calculating the oscillation frequencies f _a , f _b , f _c , and f _d of the oscillators connected to the first electrode 12a, the second electrode 12b, the third electrode 12c, and the fourth electrode 12d, The stress can also be calculated by a calculation formula.

(Modification)
As mentioned above, although the tactile sensor which concerns on this invention was demonstrated based on two embodiment, this invention is not limited to these embodiment.

  For example, in the present embodiment, a thin film such as a gold foil or a plate-like material is used as the first conductive member 11, but the present invention is not limited to this. A metal powder may be used as the first conductive member 11 and the metal powder may be dispersed in the elastic member 13. Gold powder can be used as the metal powder.

  In the present embodiment, the number of tactile hairs 14b is one, but a plurality of tactile hairs 14b may be provided. By providing a plurality of tactile hairs 14b, it becomes easier to receive an external force and the elastic member 13 is easily deformed. Thereby, the sensitivity of the sensor can be improved.

  Moreover, although the tactile hair 14b is a linear member, it need not be composed of a linear member. For example, you may provide another member in the upper part of the tactile hair 14b linear member. Thereby, since it can make it easy to receive external force, the sensitivity of a sensor can be improved. However, when detecting the direction of the external force, it is preferable that the member provided separately is a concentric member centered on the linear member so as not to affect the directivity of the external force.

  Further, in the present embodiment, the length of the tactile member 14 is the same as or slightly longer than the height of the elastic member 13 like the length of the tactile hair 14b shown in FIG. Not limited to. For example, as shown in FIGS. 9A and 9B, the length of the tactile member 14 ′ may be set to be very long with respect to the height of the elastic member 13. Thereby, the sensitivity of the tactile sensor with respect to external force can be improved. 9A and 9B, the same components as those illustrated in FIG. 1A are denoted by the same reference numerals.

  Furthermore, in this embodiment, although the wind force was illustrated as external force, external force other than wind force may be sufficient. For example, the tactile sensor according to the present invention can also be applied to hydraulic power. In this case, the water pressure and the water flow direction can be detected and measured.

  Further, in the second embodiment, the ground electrode 12GND may be formed in a donut shape, a fifth electrode may be provided inside the ground electrode 12GND, and the capacitance may be calculated. With this configuration, it is also possible to detect an external force in the vertical direction.

  In the second embodiment, the electrodes other than the ground electrode 12GND are configured with four electrodes in order to detect the direction of the external force. However, the present invention is not limited to this. For example, even two electrodes can detect two directions. Further, by configuring the number of electrodes to be four or more and calculating four or more capacitances, it is possible to detect a finer direction. However, as the number of electrodes increases, the area of the gap for separating the electrodes increases, the capacitance decreases, and the sensitivity of the sensor decreases. Therefore, it is most preferable to use four electrodes as in this embodiment.

  Furthermore, a sensor array can be configured by arranging a plurality of tactile sensors according to the present invention. By using this sensor array, an external force such as wind force can be visualized.

  In addition, it is realized by arbitrarily combining the constituent elements and functions in each embodiment without departing from the scope of the present invention, or forms obtained by subjecting each embodiment to various modifications conceived by those skilled in the art. Forms are also included in the present invention.

  The tactile sensor according to the present invention is useful as a sensor for detecting and measuring an external force. In particular, it is useful as a sensor for measuring wind speed and direction.

1, 2, 100 Tactile sensor 10 Capacitance detector 11 First conductive member 12 Second conductive member 12a First electrode 12b Second electrode 12c Third electrode 12d Fourth electrode 12GND Ground electrode 13 Elastic member 14, 14 'Tactile member 14a Base 14b Tactile hair 20 Capacitance frequency converter 21, 21a First oscillator 21b Second oscillator 21c Third oscillator 21d Fourth oscillator 22 Reference oscillator 23 Mixer 23a First mixer 23b Second mixer 23c Third mixer 23d Fourth mixer 24 Filter 25 Counter 30 Calculation Unit 31 Capacity Calculation Unit 32 External Force Information Calculation Unit 33 Memory 101 Piezoelectric Element 102 Vibrator 103 Insulating Member

Claims (7)

A first conductive member;
A second conductive member disposed at a predetermined interval from the first conductive member;
An elastic member having the first conductive member therein;
A tactile member provided on the elastic member for receiving an external force;
A detection unit for detecting the external force;
The position of the first conductive member relative to the second conductive member is displaced by deformation of the elastic member due to the external force received by the tactile member,
The said detection part detects the said external force based on the electrostatic capacitance between the said 1st conductive member and the said 2nd conductive member which changed with the displacement of the position of the said 1st conductive member. The detection unit includes a capacity frequency conversion unit, a calculation unit having a capacity calculation unit and an external force information calculation unit,
The capacitance frequency conversion unit generates a predetermined frequency signal depending on the capacitance between the first conductive member and the second conductive member,
The capacitance calculation unit calculates a value of the capacitance based on the frequency signal generated by the capacitance frequency conversion unit,
The tactile sensor according to claim 1, wherein the external force information calculation unit calculates a value of information related to the external force based on the capacitance value calculated by the capacitance calculation unit. The capacity frequency converter is
An oscillator that outputs a signal having an oscillation frequency corresponding to the capacitance;
A reference oscillator that outputs a signal of a reference oscillation frequency that is a reference oscillation frequency, and
The frequency signal generated by the capacitance frequency conversion unit is a signal having a frequency corresponding to a difference between an oscillation frequency of the signal output from the oscillator and a reference oscillation frequency of the signal output from the reference oscillator. Item 3. The tactile sensor according to Item 2. The tactile sensor according to claim 1, wherein a Young's modulus of the elastic member is 1 MPa to 100 MPa. The second conductive member includes at least a first electrode, a second electrode, a third electrode, a fourth electrode, and a ground electrode,
The first electrode and the second electrode are arranged to face each other with the ground electrode interposed therebetween,
The tactile sensor according to any one of claims 1 to 4, wherein the third electrode and the fourth electrode are disposed to face each other with the ground electrode interposed therebetween. The tactile sensor according to any one of claims 1 to 5, wherein the first conductive member is made of metal powder. The tactile sensor according to any one of claims 1 to 6, wherein the tactile member is constituted by a linear member.

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