JP2011223813A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer actuator capable of detecting displacement.SOLUTION: The actuator comprises an electrolyte membrane which incorporates movable ions, first and second driving electrode layers which are formed on both surfaces of the electrolyte membrane respectively and give the electrolyte membrane a potential difference with external voltage, and a sensor electrode layer which is formed on at least one surface of the above electrolyte membrane, extends in a direction of being bent by bending of the electrolyte membrane and detects a voltage generated on the electrolyte membrane surface.

Description

  The present invention relates to an actuator, and more particularly to an actuator having a configuration capable of detecting the direction and degree of displacement.

  One type of actuator is a polymer actuator. This actuator is a soft material such as rubber, but it bends when a voltage is applied and returns to its original when no voltage is applied. For example, electrodes are formed on both sides of the ion exchange membrane, and a potential difference is applied to the ion exchange membrane to cause deformation of the ion exchange membrane. Examples of such polymer electrolyte membrane type actuators are described in Japanese Patent Application Laid-Open Nos. H4-275078 and H11-169393.

Japanese Patent Laid-Open No. 4-275078 JP 11-169393 A

  When the polymer actuator as described above is applied to a mechanical structure such as a robot arm, it is necessary to control the bending (deformation) of the actuator. In order to perform this control, a camera, an angle sensor, or the like is used. Sensors are added to the robot arm or arranged outside the robot arm to observe (detect) the posture of the robot arm. For example, a volume is added to the axis of the joint of the robot arm to convert the angle into a resistance value, or the entire robot arm is captured by a camera, and position information is obtained by image recognition.

  However, these robot arms and other structures require sensors in addition to the actuators, and the polymer actuators themselves are relatively simple and can be made compact. It is difficult to make the whole body small.

  An object of the present invention is to provide an actuator that can constitute a small actuator structure.

  Another object of the present invention is to provide an actuator that can detect the displacement and deformation of itself.

  The actuator of one embodiment of the present invention includes an actuator material that is deformed when an electric field is applied thereto, a first drive electrode and a second drive electrode for applying the electric field to the actuator material, and a deformation of the actuator material. A sensor electrode for detecting at least one of the direction and the degree.

  According to such a configuration, since the sensor that detects at least one of the direction and degree of deformation of the actuator is integrated with the actuator, the entire structure of the actuator can be reduced in size.

  The first drive electrode and the sensor electrode are disposed on a first surface of the layer including the actuator material, and the second drive electrode is disposed on a second surface of the layer including the actuator material facing the first surface. Is preferably arranged. Thereby, an electric field can be applied in the thickness direction of the actuator material layer.

  The sensor electrode preferably detects a voltage. Accordingly, it is possible to detect at least one of the direction and the degree of deformation of the actuator material layer.

  The actuator material is preferably an electrolyte containing ions that can move when an electric field is applied. Thus, an actuator that is deformed by application of an electric field can be obtained.

  Here, the electrolyte membrane is a membrane that allows ions to pass through, and is also a membrane that has a property that the negative electrode and the positive electrode sandwiching the electrolyte membrane do not electrically short-circuit. However, the present invention is not limited to this, and any ion may be used as long as ions in the film move (or deviate) by applying a voltage and the shape of the film changes.

  According to this configuration, the sensor electrode layer is provided on the electrolyte membrane, and the charge on the membrane surface of the electrolyte membrane in which ions move and bend by application of voltage to the drive electrode layer is detected. Since this electric charge corresponds to the bending amount of the electrolyte membrane, the bending or bending (deformation amount) of the actuator can be known by the voltage generated in the sensor electrode layer. Since the sensor for detecting the deformation amount is integrated with the actuator, the entire structure of the actuator can be made compact.

  The actuator material is preferably a piezoelectric material that deforms when an electric field is applied. Similar to the electrolyte membrane, it may be deformed by applying a voltage, and may be an inorganic material. Thus, an actuator that is deformed by application of an electric field can be obtained.

  Preferably, the sensor electrode extends in one direction on the actuator material and detects a voltage corresponding to the bending of the actuator material in the one direction. Thereby, a voltage corresponding to the degree of bending (bending) in the extending direction can be detected by the sensor electrode layer.

  The sensor electrode layer preferably extends in a direction bent by the curvature of the electrolyte membrane. Thereby, the voltage generated in the curved electrolyte membrane portion can be detected by the sensor electrode layer.

  It is desirable that the first drive electrode, the second drive electrode, and the sensor electrode be spaced apart. Thereby, electrical insulation between the drive electrode layer and the sensor electrode layer is ensured, and crosstalk (noise) from the drive electrode layer to the sensor electrode layer is reduced.

  It is desirable that the sensor electrode is disposed so as to face either the first drive electrode or the second drive electrode. Thereby, an unbalanced output can be obtained from the sensor electrode layer.

  It is desirable that the sensor electrode includes a first sensor electrode and a second sensor electrode arranged so as to face each other with the actuator material interposed therebetween. Thereby, a balanced output can be obtained from the sensor electrode layer.

  The sensor electrode preferably detects a voltage corresponding to the curvature of the actuator material in the one direction by a plurality of electrodes arranged in one direction on the actuator material. Thereby, it becomes possible to detect the degree of curvature of the actuator by the voltage output of a plurality of regions.

  The sensor electrode is preferably disposed in the region of the first drive electrode or the second drive electrode. Thereby, a drive electrode layer can be arrange | positioned to an electrolyte membrane edge part, and force can be generated to an actuator edge part.

  One of the embodiments of the actuator of the present invention that solves the above-described problems is an electrolyte membrane containing ions that can move inside, and a potential difference applied to the electrolyte membrane by an external voltage formed on both surfaces of the electrolyte membrane. First and second drive electrode layers, and a sensor electrode layer that is formed on at least one surface of the electrolyte membrane and detects a voltage generated on the surface of the electrolyte membrane.

  Instead of the sensor electrode, a piezoelectric element that generates an electrical signal corresponding to the acting force may be provided in the curved portion of the electrolyte membrane.

  The above-described configurations can be appropriately combined.

  Since the actuator of the present application uses the actuator itself as a sensor by adding a sensor electrode to the actuator (electrolyte membrane), the entire structure of the actuator can be miniaturized. Also, there is almost no increase in weight due to the addition of sensors.

It is a perspective view explaining the example of the actuator of this invention. It is sectional drawing explaining the example (unbalanced output type) of the sensor electrode shown by FIG. It is sectional drawing explaining the other example (balanced output type) of a sensor electrode. It is explanatory drawing explaining the operation example of an actuator. It is a block diagram explaining the drive control system of an actuator. It is explanatory drawing explaining the structural example of another actuator. It is explanatory drawing explaining the structural example of another actuator. It is explanatory drawing explaining the structural example of another actuator. It is explanatory drawing explaining the structural example of another actuator.

The actuator of the present invention can be applied to an actuator using an electrolyte actuator material, a polymer actuator material, a piezoelectric actuator material, an electrostrictive actuator material, or the like that is deformed by application of an electric field. In the embodiment of the actuator of the present invention, an electrolyte membrane that is deformed by application of an electric field is used as an example of an actuator material, but the present invention is not limited to this. The same technique is applicable to other actuator materials that deform when an electric field is applied.
In the embodiment, for example, an ion conductive polymer electrolyte membrane is used as an actuator material that deforms when an electric field is applied. The reason why the electrolyte membrane is deformed by the application of a voltage is not exactly elucidated, but can be roughly explained as follows.

  When electrodes are formed on the front and back surfaces of the electrolyte membrane and a potential difference is generated between the front and back electrodes by a DC power source, ions in the electrolyte membrane are moved to the electrode side corresponding to the polarity by the applied electric field. Since water molecules (solvent) also move with the ions, there is a difference in the amount of water (solvent) in the electrolyte membrane between the positive electrode side and the negative electrode side of the electrolyte membrane. The electrolyte membrane swells on the side where the amount of water in the electrolyte membrane increases, and the electrolyte membrane contracts on the side where the amount of water decreases. As a result, the electrolyte membrane is curved.

Examples of the electrolyte membrane include perfluorosulfonic acid membrane (trade name “Nafion”, registered trademark of DuPont), perfluorocarboxylic acid membrane (trade name “Flemion”, registered trademark of Asahi Kasei Corporation), etc. It is possible to use a gelled material.
The electrolyte membrane has a characteristic that it bends when voltage is applied and returns to its original state when voltage is not applied.
The material of the electrolyte membrane is, for example, a rubber-like feel and is soft when no voltage is applied.

  In the present application, attention is paid to the fact that a voltage is generated in the electrolyte membrane when an external force (external stress) is applied to the electrolyte membrane. This is presumably because when the electrolyte membrane is bent, moisture is biased in the electrolyte membrane, and this causes a difference in ion density between the stretched side and the stretched side of the electrolyte membrane.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 and FIG. 2 show a configuration example of the actuator of the present application, FIG. 1 is a perspective view showing the entire actuator, and FIG. 2 is a cross-sectional view in the lateral direction of the actuator shown in FIG. As shown in each figure, the actuator 1 includes a drive electrode 11 and a sensor electrode 13 as a first drive electrode layer formed on one surface of the electrolyte membrane 10, and a second electrode formed on the other surface. And a drive electrode 12 as a drive electrode layer. The drive electrode 11 and the sensor electrode 13 are separated by a predetermined distance, for example, about 0.5 to 1.0 mm for electrical insulation.

  For example, the electrolyte membrane 10 may be a fluororesin ion exchange membrane, but is not limited thereto. As the ion exchange membrane, either a cation exchange membrane or an anion exchange membrane can be used. For example, examples of the cation exchange membrane include a perfluorosulfonic acid membrane and a perfluorocarboxylic acid membrane.

  The drive electrodes 11 and 12 and the sensor electrode 13 may be made of gold, platinum, iridium, palladium, ruthenium, carbon nanotube, or the like, but are not limited thereto. Chemical plating, electroplating, vacuum deposition, sputtering, coating, pressure bonding, welding, and the like are appropriately used for bonding the electrode to the electrolyte membrane.

  For example, in the embodiment, a perfluorosulfonic acid membrane (trade name “Nafion”, a registered trademark of DuPont) is used as the electrolyte membrane 10, and the shape thereof is 2 cm for the short side, 5 cm for the long side, and 200 μm to the thickness. It is formed in a rectangle of about 1 mm. Regarding the shape of the sensor electrode 13 described above, for example, the length (width) in the short side direction (of the electrolyte membrane 10) is 2 mm, and the length in the long side direction is 5 cm. However, it is not limited to this shape, and the shape of the electrolyte membrane 10 or the actuator can be freely selected.

In the embodiment, the drive electrodes 11 and 12 and the sensor electrode 13 are formed by applying gold plating to the electrolyte membrane 10. Gold plating on the electrolyte membrane 10 infiltrates a dichlorophenanthroline gold (III) [Au (phen) Cl ₂ ] Cl aqueous solution and adsorbs gold complex ions by an ion exchange reaction. The adsorbed film is immersed in an aqueous solution of sodium sulfite (Na ₂ SO ₃ ), and gold ions taken into the film after reduction are deposited outside. This makes it possible to apply gold plating to both sides of the film. As for the amount of gold to be plated, the amount of gold that can be plated in one plating step is 1-2 mg / cm ² on one side. This is repeated to obtain the required electrode film thickness. For example, when plating is repeated about 4 to 8 times, gold of about 10 mg / cm ^{2 on} one side is deposited. In this case, the film thickness of the gold layer (electrode layer) is approximately 1 to 5 μm.

  The gold electrode layer thus formed on one surface of the electrolyte membrane is cut with a laser in a straight line with a width of 0.5 to 1 mm necessary for electrical insulation, so that the drive electrode 11 and the sensor electrode 13 are formed. To be separated. The sensor electrode 13 extends in the longitudinal direction of the electrolyte membrane 10 and detects a potential difference (voltage) between the electrode layers 12 and 13 generated on the curved surface by the bending operation of the actuator. The sensor electrode 13 may be formed on either the front surface or the back surface of the electrolyte membrane 10.

  FIG. 3 is a cross-sectional view illustrating another configuration example of the actuator. In the figure, parts corresponding to those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

  In this embodiment, the sensor electrode is constituted by a pair of electrode layers 13 and 14. The electrode layers 13 and 14 are formed by gold plating, and are configured to sandwich the electrolyte membrane 10. Although the detection output of the sensor electrode 13 having the configuration of FIG. 2 is an unbalanced output, according to the configuration of this embodiment, the detection output of the balanced output can be obtained at the sensor electrodes 13 and 14.

  FIG. 4 is an explanatory diagram illustrating an operation example of the actuator 1. In the figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

  As shown in the figure, when a negative voltage and a positive voltage are applied to the drive electrode layers 11 and 12 of the actuator 1 from a DC power source, the anions in the electrolyte membrane 10 move to the drive electrode layer 12 side. Accordingly, the moisture on the drive electrode layer 11 side relatively decreases, the moisture on the drive electrode 12 side relatively increases, and as shown in FIG. 4, the actuator 1 is bent and bent to the left. Similarly, when a positive voltage and a negative voltage are respectively applied to the drive electrode layers 11 and 12 from the DC power supply, the anions in the electrolyte membrane 10 move to the drive electrode layer 11 side. The moisture on the drive electrode layer 12 side is relatively decreased and the moisture on the drive electrode 11 side is relatively increased. As shown in FIG. 4, the actuator 1 is bent and bent to the right.

  FIG. 5 is a block diagram illustrating the control system 30 that drives the actuator 1 described above. As shown in the figure, the detection voltage of the sensor electrode 13 is level-amplified by an amplifier 31 and input to a negative phase input of a comparator (differential amplifier) 32. The comparator 32 is supplied with a voltage corresponding to the current position of the actuator 1. The target value of the operation amount of the actuator 1 is input as a voltage value to the positive phase input of the comparator 32. The comparator 32 outputs the deviation between the sensor electrode voltage and the target value. The drive circuit 33 determines the direction of movement of the actuator 1 according to the polarity (positive or negative) of the deviation output, and determines the polarity of the output voltage. Further, the level of the output voltage is set by determining how much the actuator 1 is bent in accordance with the absolute value of the deviation output.

  The output voltage of the drive circuit 33 is supplied to the drive electrodes 11 and 12 of the actuator 1. The actuator 1 bends (bends) in a direction corresponding to the polarity of the output voltage of the drive circuit 33, and has a bend amount (bend amount) corresponding to the level of the output voltage. When the actuator 1 is curved, if the actuator 1 receives stress from the outside, the voltage of the sensor electrode 13 changes. Therefore, the changed value is fed back to the comparator 32 and the difference from the target value is used as a deviation. Output and correct. By this feedback control loop, the actuator 1 moves to a position corresponding to the set target value and is stabilized.

6 and 9 show another configuration example of the actuator 1. In each figure, the same reference numerals are given to portions corresponding to those in FIG.
In these examples, sensors are arranged so as to detect bending (bending) or deformation in a plurality of directions.

  In the actuator 1 of FIG. 6, two actuators are arranged in the vertical direction in the figure, and power is supplied to the drive electrodes 11 and 12 in the central portion in the vertical direction. When the actuator 1 receives the drive signal, the actuator 1 bends in a U shape and an inverted U shape. The sensor electrode 13 is disposed so as to extend along the drive electrode 11 in the extending direction of the electrolyte membrane 10.

  In the actuator 1 of FIG. 7, four actuators are arranged in the vertical (Y) direction and the horizontal (X) direction in the figure. The sensor electrodes are also arranged in the X direction and the Y direction, and are arranged along a curved surface. An external connection terminal for connecting to the control circuit 30 or the like is provided at the center. In this actuator, the cruciform actuator opens, closes, and warps to act like the palm of a robot (or human). Also, the four actuators can be operated individually.

  Although not specifically shown, the actuator 1 is arranged in the X-axis direction, the Y-axis direction, and the Z-axis direction (three-dimensional), and the sensor electrodes 13 are arranged in the X-direction, Y-direction, and Z-direction, respectively. You may do it. Thereby, the actuator which operates in three dimensions can be controlled. Further, the sensor electrode 13 may be arranged in an oblique direction with respect to the X direction, the Y direction, and the Z direction. A voltage corresponding to the degree of curvature of the actuator in the extending direction of the sensor can be detected.

In the above embodiment, the sensor electrode extends in one direction, and generates one output corresponding to the bending (bending) of the actuator in this direction, but is not limited thereto.
For example, as shown in FIG. 8, a plurality of sensor electrodes 13 having a square shape or the like are arranged along the extending direction of the drive electrode 11, and the curved (bent) shape of the actuator is determined based on each output of the sensor electrode 13. You may do it. Also in this case, a sensor electrode configuration of unbalanced output and balanced output as shown in FIG. 2 or FIG. 3 can be obtained. Moreover, it can be set as the structure which combined multiple actuators like FIG. 6 or FIG.

  FIG. 9 shows still another embodiment of the actuator. In this example, the sensor electrode 13 extending in one direction is disposed in the region of the drive electrode 11 (substantially central region thereof). With such a configuration, it is not necessary to arrange the sensor electrode on the outer periphery of the actuator, so that it is possible to avoid a decrease in driving force of the portion. Also in this case, a sensor electrode configuration of unbalanced output and balanced output as shown in FIG. 2 or FIG. 3 can be obtained. Moreover, it can be set as the structure which combined multiple actuators like FIG. 6 or FIG.

  As described above, according to the embodiment of the present invention, since the sensor electrode is provided on the polymer actuator, it is possible to detect the movement of each actuator or its posture by this output. Since the sensor electrode is formed at the same time as the drive electrode, it is easy to manufacture and is small because it fits in the actuator. The cost of the sensor is low. By using the actuator in which the sensor electrode is formed, an actuator structure such as a robot arm can be made compact.

  A similar effect can be expected even when a piezoelectric element such as PZT that generates a voltage corresponding to the applied pressure or a resistance value changing element such as a strain gauge is used on the electrolyte membrane instead of the sensor electrode.

Further, the frequency of the actuator can be detected from the output of the sensor (electrode or the like), and the repetition frequency and cycle such as flapping by the polymer actuator can be controlled.
The present invention can be widely applied without departing from the gist of the present invention, and can be applied to an actuator using a piezoelectric actuator material, an electrostrictive actuator material, etc. in addition to an electrolyte actuator material and a polymer actuator material. is there.

DESCRIPTION OF SYMBOLS 1 Actuator, 10 Electrolyte membrane, 11, 12 Drive electrode, 13 Sensor electrode, 30 Drive control system, 31 Amplifier, 32 Comparator, 33 Drive circuit

Claims (10)

An actuator material that deforms when an electric field is applied;
A first drive electrode and a second drive electrode for applying the electric field to the actuator material;
A sensor electrode for detecting at least one of the direction and degree of deformation of the actuator material;
Actuator with. The first drive electrode and the sensor electrode are disposed on a first surface of the layer containing the actuator material;
2. The actuator according to claim 1, wherein the second drive electrode is disposed on a second surface of the layer containing the actuator material opposite to the first surface.   The actuator according to claim 1, wherein the sensor electrode detects a voltage.   4. The actuator according to claim 1, wherein the actuator material is an electrolyte containing ions that can move when the electric field is applied. 5.   The actuator according to any one of claims 1 to 4, wherein the sensor electrode is arranged to extend in one direction on the actuator material, and detects a voltage corresponding to the curvature of the actuator material in the one direction.   The actuator according to any one of claims 1 to 5, wherein the first drive electrode, the second drive electrode, and the sensor electrode are spaced apart from each other.   The actuator according to any one of claims 1 to 6, wherein the sensor electrode is disposed so as to face either the first drive electrode or the second drive electrode.   The actuator according to any one of claims 1 to 7, comprising a first sensor electrode and a second sensor electrode arranged so that the sensor electrodes face each other with the actuator material interposed therebetween.   The actuator according to any one of claims 1 to 4, wherein the sensor electrode detects a voltage corresponding to the curvature of the actuator material in one direction by a plurality of electrodes arranged in one direction on the actuator material.   The actuator according to claim 1, wherein the sensor electrode is disposed in a region of the first drive electrode or the second drive electrode.

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