JP3117045B2 - Angle sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automatic control of free bending / extension or rotation movement around a fulcrum of various joints of a robot, or research and diagnosis by observing complicated movements of various joints of animals including humans. The present invention relates to an angle sensor using a resin piezoelectric element used in an apparatus or the like for performing the above.

[0002]

2. Description of the Related Art There is an angle sensor using a magnetoresistive element that outputs a rotational angular displacement of an arm portion or the like that performs a rotational movement about a rotational axis as an electric signal. Further, there is a strain gauge that outputs the amount of strain of a substance due to external mechanical energy as an electric signal.

Further, there has been an attempt to use a sensor using a resin piezoelectric material as a sheet material as an angle sensor.

[0004]

SUMMARY OF THE INVENTION Among the above sensors,
In the case of the magnetoresistive element, the rotation angle can be measured or detected by attaching the sensor to the rotation axis of the rotational motion, but the one that performs planar rotation about the shaft axis can be used. Limited use. Therefore, it cannot be used for measuring a human or an arm of a robot that moves complicatedly. Also, in the case of a strain gauge, even if pressure can be measured,
The angular displacement cannot be expected very much.

Further, it has not been possible to output a highly reproducible angular displacement signal using only a conventional sensor using a resin piezoelectric material as a sheet material. This is because bending and stretching stresses from the object to be measured are not accurately transmitted to the sensor.

[0006] As for a sensor capable of sensing a rotational angular displacement and outputting an electric signal directly to a computer as an information source, a F which realizes general-purpose automation using a robot or the like is used.
This is a necessary technology for A-system. The applicant of the present invention has conventionally responded to the demand for establishing this technology. In this regard, a piezoelectric material, which has the property of generating a charge in proportion to the amount of stress and strain of a crystal generated by external mechanical energy, is converted into a joint during rotational movement by the technology of combining inorganic and organic materials. We succeeded in improving it as a flexible material that can withstand (fulcrum) refraction.

[0007] That is, an object of the present invention is to provide an angle sensor capable of extracting mechanical energy such as a flexible bending and stretching movement having a high degree of freedom of a joint as an accurate and reproducible electric signal output.

[0008]

In order to achieve the above object, the present invention provides a flexible resin piezoelectric element by mixing a ceramic fine powder having high piezoelectric characteristics into an epoxy resin having piezoelectric characteristics. An electrode was formed in a planar shape on the outer surface of the resin piezoelectric element with a portion serving as a fulcrum of bending and elongation forming an angle sensor.

[0009] In addition, at a position that becomes a fulcrum of bending and stretching,
If the left and right arm members giving the operation are connected so as to abut each other, the fulcrum can be limited in order to enhance reproducibility (claim 2). In addition, if the resin piezoelectric element is formed in a cylindrical shape using a flexible support member as a core material, the rotation angle can be freely set (claim 3).

[0010]

[Function] Since the angle sensor is configured as described above, it is not only flexible from the epoxy resin material, but also a composite material in which ceramic material having high piezoelectric characteristics is mixed into the material in addition to the piezoelectric characteristics. , It has very high piezoelectric properties. In addition, it has heat resistance and moisture resistance, good adhesiveness, and flexibility in molding as resin characteristics.

The ratio of the fine ceramic powder to the whole of the resin piezoelectric element is preferably about 10 to 40%. Below this, piezoelectric properties are not obtained as desired, and above that, flexibility is lacking.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 show an embodiment in which the angle sensor has a sheet shape, and a resin piezoelectric element 2 as a main body is formed in a rectangular sheet shape. Electrodes 1 and 3 are formed in a planar shape on both upper and lower surfaces of the intermediate portion as a bent portion, and electric wires 4 and 5 are drawn from both electrodes 1 and 3.

For the resin piezoelectric element 2, fine powder of PZT, which is a ceramic material having high piezoelectric characteristics, is used. As a main component, a bisphenol-type epoxy resin containing a microcrystal-imparting agent, which is a flexible polymer material having piezoelectric characteristics, was used. Ceramic fine powder was mixed therewith and molded into a rectangular sheet as described above. According to this, by combining the inorganic substance and the organic substance, it is possible to flexibly cope with the bending and elongation of the fulcrum during the rotational movement.

The PZT fine powder was prepared by Fuji Titanium Industry Co., Ltd., having an average particle diameter of 4 μm, and 20%, and 80% of a piezoelectric epoxy resin was blended in a weight ratio.

The electrodes 1 and 3 were formed in a planar shape using carbon paste in consideration of flexibility. Also, copper foil, silver foil,
It can also be formed by printing a silver conductive paint on the surface of the resin piezoelectric element 2 using an aluminum foil or the like, and then baking and curing the foil.

The electric wires 4 and 5 do not impair the flexibility of the resin piezoelectric element 2 and have high impedance for use in measuring a small amount of static charge with a charge amplifier. And a flexible film such as a polyester film or a polyimide film as a base material, and a fine powder such as carbon, silver, or copper was blended with a flexible polyvinyl alcohol to have conductivity. Examples thereof include those in which a wiring pattern is printed on a film of a base material with a polymer, and those in which a wiring pattern of aluminum foil or copper foil is adhered.

An example of a procedure for manufacturing the angle sensor is as follows. 1) Kneading The epoxy resin and the PZT powder are kneaded in an automatic mortar for 2 hours. 2) Inject the kneading material into the casting mold. At that time, the mold temperature is raised to 60 ° C., vacuum degassing is performed, and air in the resin is removed. 3) Curing It is cured in a constant temperature bath of 160 ° C. for one hour. 4) Polarization After a lapse of 1 hour at a voltage of 50 kv / cm in the thickness direction of the cured material in a temperature atmosphere of 150 ° C., the temperature is lowered to room temperature while the voltage is applied. 5) Electrode A room temperature curing type silver paste is applied to the electrode forming surface and cured. When silver paste that can cause migration is used for the electrode, compared to carbon paste and copper paste,
Excellent resistance and flexibility.

Next, experimental results of the angle sensor of the above embodiment will be shown. As shown in FIG. 11, the experiment method assumes a cantilever with a span of 250 mm and a free end of 0.3 k.
A gf weight was attached, the sample was tensioned, bent with a balsa notch, passed through a charge amplifier, and the output voltage was measured. FIG. 12 is a table showing the experimental results. According to this table, a proportional relationship is recognized between the output voltage and the notch moving distance. When the notch moving distance becomes 50 mm or more, the output voltage with respect to the distortion is saturated. It is. The speed of the notch is not considered. Regarding the responsiveness, after applying the weight, the maximum output voltage is shown at 0.5 msec, regardless of the strength of the weight, and is 8 msec.
It exhibited extremely excellent characteristics of being attenuated within.

FIGS. 3 to 5 show an embodiment in a basic structure for measuring a bending angle of a fulcrum A of a hinge portion. Two arm members 6a and 7a are bonded to the angle sensor. did. At this time, the resin piezoelectric element 2 also serves as a hinge for the two arm members 6a, 7a.

When the angle sensor is configured in this manner, as shown in FIG. 5, the strain of the flexible resin piezoelectric element 2 can be concentrated on the fulcrum A of bending and elongation.

FIGS. 6 to 8 show still another embodiment. In this case, the resin piezoelectric element 2 is inserted into the left and right arm members 6b and 7b, and the arm members 6b and 7b are The thickness is reduced toward the ends on both butting sides.

When the angle sensor is configured in this manner, as shown in FIG. 8, both arm members 6b and 7b can be turned upside down. Also in this case, the rotation of the arm members 6b and 7b is concentrated only on the mechanical fulcrum B, and the output result becomes constant. Can be output.

FIG. 9 shows still another embodiment. In this case, a flexible support member 8 is used as a core material, and a resin piezoelectric element 2 'and electrodes 1', 3 'are provided around the core material.
Is formed, and the angle sensor is formed in a columnar shape, thereby providing three-dimensional bending / extending freedom.

The material of the support member 8 is desirably a gel or rubber-like flexible polymer such as flexible epoxy resin or urethane rubber, or a flexible metal without elastic deformation. Next, a manufacturing method for a flexible epoxy resin will be described.

1) The support member 8 is formed by a casting method. 2) Bake the periphery of the support member 8 with a flexible conductive polymer (carbon conductive paint) to form the electrodes 1 'and 3'. 3) Connect wires 4 ', 5' to the ends of the planar electrodes 1 ', 3'. 4) The post member 8 having been subjected to the above processing is fixed to the center of a column-shaped casting mold having a radius larger by 1 mm. To 1mm gap between the mold shell and the cylindrical strut members 8, the piezoelectric epoxy resin unreacted high vacuum (10- ⁵ torr)
Pour in a vacuum chamber. It is taken out of the vacuum chamber and cured by heating (160 ° C., 1 hour). 5) The electrodes 1 ', 3' are formed by baking the circumference of the cylinder with a flexible conductive polymer (carbon conductive paint) with a width of about 5 mm around the fulcrum. 6) Concentric cylindrical electrodes 1 formed at 150 ° C. for 1 hour
An electric field of 5 kv is applied between 'and 3', and after polarization, the electric field is removed after cooling.

FIG. 10 shows the angle sensor of FIG. 9 embedded in and joined to arm members 6c and 7c.
It is designed to concentrate power on the fulcrum.

[0028]

As described above, the angle sensor of the present invention is a composite resin piezoelectric element which is flexible from a flexible epoxy resin material and is mixed with ceramic powder having high piezoelectric characteristics. In addition, if it is attached to various joints such as humans and robots, such as fingers, elbows, knees, etc., which have a high degree of freedom, the displacement of the rotation angle can be detected accurately and promptly, and a highly reproducible electric signal is generated. It has an excellent effect of being able to do so.

In addition, it has heat resistance, moisture resistance, good adhesiveness, and freedom in molding, and has the effect that it can be used for an extremely wide range of applications.

In addition, at a position that becomes a fulcrum of bending and stretching,
If the left and right arm members that give the operation are connected so as to abut each other, mechanical energy is concentrated on the fulcrum, and an output with high reproducibility can be obtained (claim 2). Further, if the resin piezoelectric element is formed in a columnar shape using a flexible support member as a core material, it becomes easy to freely take a three-dimensional rotation angle (claim 3).

[Brief description of the drawings]

FIG. 1 is a plan view of an angle sensor showing one embodiment.

FIG. 2 is a side view of the sensor.

FIG. 3 is a plan view showing another embodiment.

FIG. 4 is a side view of the same.

FIG. 5 is a side view showing a state of angular displacement of the angle sensor.

FIG. 6 is a plan view showing still another embodiment.

FIG. 7 is a side view of the embodiment.

FIG. 8 is a side view showing a state of angular displacement of the angle sensor.

FIG. 9 is a plan view showing still another embodiment.

FIG. 10 is a side view showing still another embodiment.

FIG. 11 is an explanatory diagram showing an experimental example of the first embodiment.

FIG. 12 is a table showing the results of the same experiment.

[Explanation of Signs] 1, 1 ', 3, 3' Electrode surface 2, 2 'Resin piezoelectric element 4, 4', 5, 5 'Electric wire 6a, 6b, 6c, 7a, 7b, 7c Arm member 8 Flexible A certain strut member

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B ⁷ /00-7/34 102 G01D 5/00-5/252 G01D 5/39-5/62 G01L 1/00- 1/26 G01L 25/00

Claims (3)

(57) [Claims] 1. A ceramic fine powder having high piezoelectric properties is
An angle characterized by forming a flexible resin piezoelectric element by mixing it with epoxy resin having piezoelectric characteristics, and forming an electrode on the outer surface of the resin piezoelectric element with a point serving as a fulcrum of bending and stretching between the electrodes. Sensor. 2. The angle sensor according to claim 1, wherein the right and left arm members for giving the operation are abutted at a position serving as a fulcrum of bending and extension, and the resin piezoelectric element is connected so as to bend as a hinge. 3. The resin support element according to claim 1, wherein the flexible support member is a core material and the resin piezoelectric element is formed in a cylindrical shape.
Or the angle sensor according to 2.