JP2011234530A - Driving apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving apparatus capable of determining an insulating state in an operation state of a high polymer actuator.SOLUTION: The driving apparatus has: a high polymer actuator 10; a driving part 20 that outputs a driving signal for driving the high polymer actuator 10; a detector 40 that generates a signal for determination from an output current value outputted when the high polymer actuator 10 is driven and the driving signal; a controller 50 that determines the insulating state of the high polymer actuator 10 based on the driving signal and the signal for determination; and a switch part 30 that switches over a state of outputting the driving signal to the high polymer actuator 10 and a state of blocking the driving signal, based on an instruction from the controller 50. In addition, when the controller 50 has determined that the high polymer actuator 10 is in an insulation breakdown state, the controller 50 issues an instruction to the switch part 30 to block the driving signal, and stops electric conduction to the high polymer actuator 10.

Description

  The present invention relates to a drive device, and more particularly, to a drive device including a polymer actuator.

  Conventionally, a polymer actuator is known as a displacement element for generating a minute displacement. Since such a polymer actuator is considered to be flexible and capable of being manufactured in large quantities and can be manufactured at a low cost, various methods have been studied.

  Examples of the polymer actuator system include an ion conductive polymer actuator, a conductive polymer actuator, and a dielectric polymer actuator. Among them, the dielectric polymer actuator is attracting attention because it can obtain a larger displacement and operating speed.

  A dielectric polymer actuator has a structure in which a displacement layer made of a dielectric polymer (dielectric elastomer) is sandwiched between electrodes. When a voltage is applied between the electrodes, the dielectric elastomer is elasticized by the Coulomb force generated between the electrodes. The pressure is deformed within the range and the displacement is output. As an example of such a polymer actuator, an actuator having a dielectric elastomer layer between electrodes is disclosed in Patent Document 1, for example.

JP 2009-124875 A

  Here, in the dielectric polymer actuator, if the driving is repeated, there may be a case where minute breakage occurs inside the displacement layer made of the polymer due to the deformation operation at the time of driving. Since the electrical resistance is small at the minute damaged portion, a leakage current is generated when voltage application is continued in this state. Although the leakage current is very small at the initial stage of damage, the influence of the damage is small, but if the drive is continued as it is, the damage will progress and the amount of leakage current will increase as the damage progresses, increasing Joule heat due to electrical resistance. To do. When the temperature of the displacement layer exceeds the melting point of the polymer due to a temperature rise due to Joule heat, the polymer dissolves and breakage of the displacement layer progresses at a stretch, which may lead to breakage that cannot be used as an actuator. Moreover, when a polymer is combustible, it may be ignited and damaged by Joule heat. In either case, damage is caused by a dielectric breakdown mechanism, but if this occurs during use of the actuator, the drive device itself may be damaged.

  In order to prevent breakage due to these dielectric breakdowns, it is effective to detect the leakage current at the initial stage before the breakage of the actuator and stop the voltage application.

  Regarding the detection of leakage current, a capacitor insulation diagnosis method is conventionally known in which an alternating voltage is applied to an insulator, the leakage current is measured, and an insulation diagnosis is performed based on the relationship between the applied voltage and the leakage current. . In this method, a partial deterioration of an insulator such as a void is reflected in the leakage current as a change in dielectric loss tangent (tan δ).

  Since the above-described polymer actuator (dielectric polymer actuator) can also be said to be a capacitor in a broad sense, in principle, it is considered possible to detect the insulation state using conventional techniques.

  However, unlike a general capacitor, a polymer actuator has a displacement layer (dielectric polymer) that compresses and deforms due to the Coulomb force generated between the electrodes when the actuator is in an operating state. The distance between the electrodes changes). For this reason, since the capacitance changes, there arises a disadvantage that the state of the leakage current that is a criterion for the insulation state changes. Therefore, the conventional method described above has a problem that it is difficult to determine the insulation state.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a drive device capable of determining an insulation state in an operation state of a polymer actuator. It is.

  Another object of the present invention is to provide a driving device in which safety is improved by detecting an insulation state of a polymer actuator.

  In order to achieve the above object, a drive device according to one aspect of the present invention includes a polymer actuator including a displacement layer made of a dielectric elastomer, a drive unit that outputs a drive signal for driving the polymer actuator, A detection unit that generates a determination signal according to the drive signal from an output current value output when the molecular actuator is driven, a control unit that determines an insulation state of the displacement layer from the drive signal and the determination signal, and a control unit And a switch unit that switches between a state in which a drive signal is output to the polymer actuator and a state in which the drive signal is blocked based on an instruction from the controller. And when the said control part determines with the displacement layer being a dielectric breakdown state, it gives the instruction | indication which interrupts | blocks a drive signal to a switch part, and stops the electricity supply to a polymer actuator.

  In the drive device according to this aspect, as described above, when the displacement layer is compressively deformed and its volume is changed by providing the detection unit that generates the determination signal according to the drive signal from the output current value However, a determination signal corresponding to the volume change can be generated. And by providing the control part which determines the insulation state of a displacement layer from a drive signal and the signal for determination, the insulation state of a displacement layer can be determined in the operation state of a polymer actuator. By determining the insulation state of the displacement layer, the insulation state of the displacement layer in the polymer actuator can be detected, and the leakage current in the initial stage before the actuator is damaged can be detected.

  Also, in one aspect, when the control unit determines that the displacement layer is in a dielectric breakdown state, the control unit issues an instruction to shut off the drive signal to stop energization of the polymer actuator. With this configuration, it is possible to stop the operation of the polymer actuator at the initial stage of breakage, so that the progress of breakage in the displacement layer can be suppressed. As a result, it is possible to suppress the damage of the drive device itself due to the dielectric breakdown of the polymer actuator, so that safety can be improved.

  In the driving device according to the above aspect, it is preferable that the detection unit is configured to generate a determination signal from the driving signal and the output current value. If comprised in this way, since the signal for determination according to a drive signal can be produced | generated easily, the insulation state in the operation state of a polymer actuator can be determined easily.

  In the drive device according to the above aspect, the detection unit includes a detection signal output unit that outputs a detection signal to be superimposed on the drive signal, and is configured to generate a determination signal from the detection signal and the output current value. You can also If comprised in this way, while the signal for determination according to a drive signal can be produced | generated easily, the insulation state in the operation state of a polymer actuator can be determined with sufficient precision.

  In this case, the detection signal is preferably an AC signal having a frequency two orders of magnitude higher than the frequency of the drive signal.

  As described above, according to the present invention, it is possible to easily obtain a drive device that can determine an insulation state in an operation state of a polymer actuator.

  In addition, according to the present invention, it is possible to easily obtain a drive device with improved safety by detecting the insulation state of the polymer actuator.

It is a block diagram showing a schematic structure of a drive device by a 1st embodiment of the present invention. It is sectional drawing which shows schematic structure of the polymer actuator by 1st Embodiment of this invention. It is a block diagram which shows schematic structure of the detection part of the drive device by 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of the drive device by 1st Embodiment of this invention. It is a block diagram which shows schematic structure of the drive device by 2nd Embodiment of this invention. It is a block diagram which shows schematic structure of the detection part (phase detection part) of the drive device by 2nd Embodiment of this invention. It is a figure for demonstrating operation | movement of the drive device by 2nd Embodiment of this invention. It is a figure (graph which showed an example of a waveform of an output current value) for explaining operation of a drive unit by a 2nd embodiment of the present invention. FIG. 10 is a diagram for explaining the operation of the drive device according to the second embodiment of the present invention (a diagram showing an example of a detection signal and a binary signal (X)). It is a figure for demonstrating operation | movement of the drive device by 2nd Embodiment of this invention (The figure which showed an example of the waveform of the output electric current value after AC coupling). It is a figure for demonstrating operation | movement of the drive device by 2nd Embodiment of this invention (The figure which showed an example of an output current value and a binary signal (Y)). FIG. 10 is a diagram (an example showing a binary signal (X), a binary signal (Y), and an XOR (phase difference signal)) for explaining the operation of the driving apparatus according to the second embodiment of the present invention. FIG. 10 is a diagram (a diagram showing a CR parallel circuit) for explaining the operation of the drive device according to the second embodiment of the present invention. It is a figure (vector diagram of CR parallel circuit of FIG. 13) for demonstrating operation | movement of the drive device by 2nd Embodiment of this invention. It is a figure for demonstrating operation | movement of the drive device by 2nd Embodiment of this invention (The figure which showed an example of the signal waveform which shows the phase shift degree with respect to time).

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of a driving apparatus according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a schematic configuration of the polymer actuator according to the first embodiment of the present invention. FIG. 3 is a block diagram showing a schematic configuration of the detection unit of the drive device according to the first embodiment of the present invention. First, with reference to FIGS. 1-3, the structure of the drive device by 1st Embodiment of this invention is demonstrated.

  As shown in FIG. 1, the drive device according to the first embodiment includes a polymer actuator 10, a drive unit 20 that outputs a signal (drive signal) for driving the polymer actuator 10, and a signal from the drive unit 20. A switch unit (SW unit) 30 that switches output / blocking of (drive signal), a detection unit 40 that detects an insulation state of the polymer actuator 10, and a control unit 50 that controls opening and closing of the switch unit 30 are provided. .

  As shown in FIG. 2, the polymer actuator 10 is made of a dielectric polymer actuator in which both sides of a displacement layer 5 made of a dielectric elastomer (dielectric polymer) which is a soft elastic material are sandwiched between soft elastic electrode layers 6 and 7. .

  As shown in FIG. 1, the displacement layer 5 of the polymer actuator 10 is electrically (equivalent circuit-like) in which a capacitor component 5a having dielectric characteristics and a resistance component 5b having insulating characteristics are connected in parallel. Can be expressed as Therefore, in the polymer actuator 10 as a whole, the electrode layers 6 and 7 (see FIG. 2) are connected to both ends of the parallel connection of the capacitor component 5a and the resistance component 5b, which corresponds to the dielectric elastomer (the displacement layer 5 (see FIG. 2)). The resistance components 6a and 7a corresponding to) can be expressed in a configuration connected in series.

  As shown in FIG. 1, the drive unit 20 is connected to the polymer actuator 10 via the switch unit 30, and has a function of applying (outputting) a drive voltage as a drive signal to the polymer actuator 10. Yes. The drive signal is also connected to the control unit 50 and the detection unit 40, and outputs the same drive signal (drive voltage) as the drive signal output to the polymer actuator 10 to the control unit 50 and the detection unit 40. . Note that when the drive signal is input to the polymer actuator 10, a current value (output current value) is output from the polymer actuator 10.

  The detection unit 40 generates a determination signal for determining the insulation state of the polymer actuator 10 from the output current value from the polymer actuator 10 and the drive signal from the drive unit 20. Further, as shown in FIG. 3, the detection unit 40 includes an AC coupling 41 to which a drive signal is input, an A / D conversion unit 42 to which an output current value is input, and an A / D conversion unit 42. And an integration unit 43 that integrates the A / D converted output current value.

  As shown in FIG. 1, the control unit 50 has a function of calculating a criterion value for determining the insulation state of the polymer actuator 10 based on a drive signal (drive voltage) from the drive unit 20. is doing. Further, the control unit 50 determines the insulation state of the polymer actuator 10 from the calculated determination reference value and the determination signal from the detection unit 40. When it is determined that the polymer actuator 10 is in a dielectric breakdown state, the switch unit 30 is instructed to shut off the drive signal, and energization of the polymer actuator 10 is stopped.

  The switch unit 30 switches between a state in which a drive signal is output to the polymer actuator 10 and a state in which the drive signal is blocked based on an instruction from the control unit 50.

  FIG. 4 is a diagram for explaining the operation of the driving apparatus according to the first embodiment of the present invention. 4A shows an example of the waveform of the drive signal (drive voltage) output from the drive unit, and FIG. 4B shows the drive signal (drive voltage) after AC coupling. ) Shows an example of a waveform. Next, with reference to FIGS. 1-4, operation | movement of the drive device by 1st Embodiment of this invention is demonstrated.

  First, as shown in FIG. 1, a drive signal (drive voltage) is output from the drive unit 20 to the polymer actuator 10. At this time, the same drive signal as the drive signal output to the polymer actuator 10 is also output from the drive unit 20 to the detection unit 40 and the control unit 50. For example, a drive signal having a waveform as shown in FIG. 4A is output from the drive unit 20.

  When a driving signal (driving voltage) is applied to the polymer actuator 10, as shown in FIG. 2, the displacement layer 5 is charged and charges are accumulated in the capacitor component 5a (see FIG. 1) of the displacement layer 5. . An electrostatic attraction (Coulomb force) acts between the electrode layer 6 and the electrode layer 7 by the electric field generated by the applied voltage, and the electrode layers attract each other. Thereby, the displacement layer 5 which is a soft elastic body contracts in a direction (B1 direction) perpendicular to the layer surface and extends in a direction (A1 direction) along the layer surface. That is, the displacement layer 5 is compressed and deformed so as to increase the area. On the other hand, when the charge charged in the displacement layer 5 is discharged, the displacement layer 5 is deformed in the opposite direction. Thus, the polymer actuator 10 performs a driving operation according to the driving signal (driving voltage).

  Here, in a state where dielectric breakdown does not occur in the polymer actuator 10 (displacement layer 5), the capacitor component 5a (see FIG. 1) has a predetermined capacitance, and the resistance component 5b (see FIG. 1) has a predetermined value. Insulation resistance. For this reason, the capacitor component 5a and the resistance component 5b act on the polymer actuator 10 (displacement layer 5) in accordance with the input signal (drive signal (drive voltage)) and become a predetermined amount of current. On the other hand, when dielectric breakdown occurs in the displacement layer 5, the insulation resistance (resistance component 5b) decreases according to the degree of damage, and accordingly, the leakage current flowing through the resistance component 5b increases and the measured current amount also increases. To do. Therefore, if the increase in the amount of current due to dielectric breakdown is measured (detected), the insulation state of the polymer actuator 10 (displacement layer 5) can be detected.

  On the other hand, when a drive signal is input to the polymer actuator 10, an output current value is output, and this output current value is input to the detection unit 40. That is, the drive signal and the output current value are input to the detection unit 40.

  The drive signal input to the detection unit 40 passes through the AC coupling 41 to output a differential component. As shown in FIG. 4B, the drive signal (drive voltage) changes (voltage change) timing. Rising and falling signals (timing signals) are obtained.

  As shown in FIG. 3, the output current value input to the detection unit 40 is A / D converted by the A / D conversion unit 42, and the timing signal falling from the rising edge of the drive signal is output (FIG. 4). The integration unit 43 performs integration for t) in (b). Then, the detection unit 40 outputs the integrated value to the control unit 50 as a determination signal.

  The controller 50 first determines the insulation state of the polymer actuator 10 (displacement layer 5) based on the determination signal. The determination signal is an integral value of the current for a predetermined time after the drive signal is input. In a state where dielectric breakdown does not occur, the capacitance and the insulation resistance of the displacement layer 5 (dielectric polymer) are predetermined. And the current integrated value (integrated amount) corresponding to the value. However, during the driving operation of the polymer actuator 10, the volume of the displacement layer 5 (dielectric polymer) changes according to the driving signal (driving voltage), and the capacitance also changes accordingly. For this reason, the integrated value (integrated amount) of the current output from the polymer actuator 10 also changes.

  Here, in the first embodiment, in the control unit 50, based on the input drive signal (drive voltage), the current value (current value integrated value) of the polymer actuator 10 in a state where dielectric breakdown has not occurred. ) And this value is used as the value for the determination criterion. The determination reference value changes according to the change of the drive signal (drive voltage).

  Then, the control unit 50 compares the calculated determination reference value with the determination signal from the detection unit 40, and if the determination signal exceeds the determination reference (determination reference value). The leakage current is increased and it is determined that dielectric breakdown has occurred. That is, since leakage current increases when dielectric breakdown occurs, the detection signal, which is an integrated value of the output current value, becomes higher than the determination reference value. However, more accurate control is possible by taking into account error factors such as measurement errors and making judgments on the value of the criterion + error.

  When the control unit 50 determines that dielectric breakdown has occurred (determined to be in a dielectric breakdown state), the control unit 50 instructs the switch unit 30 to shut off the drive signal, and the switch unit 30 Cut off the actual signal. By blocking this signal, the energization to the polymer actuator 10 is stopped, and damage due to further driving operation is prevented.

  As described above, in the drive device according to the first embodiment, the state of the leakage current that becomes the determination reference with respect to the drive signal (drive voltage) applied to the displacement layer 5 (dielectric polymer) during the drive operation of the polymer actuator 10 is determined. By calculating, it is possible to determine the insulation state by applying a criterion according to the volume change of the displacement layer 5 (dielectric polymer). For this reason, it is possible to detect the leakage current in the initial stage before the polymer actuator 10 is damaged.

  Further, in the first embodiment, as described above, even when the displacement layer 5 of the polymer actuator 10 is compressively deformed and its volume changes, a determination signal corresponding to the volume change can be generated. The insulation state of the polymer actuator 10 (displacement layer 5) can be determined by comparing the determination reference value calculated by the control unit 50 with the determination signal. Then, by stopping the operation of the polymer actuator 10 at the initial stage of breakage, the progress of breakage in the displacement layer 5 can be suppressed. As a result, it is possible to suppress damage to the drive device itself due to the dielectric breakdown of the polymer actuator 10, so that safety can be improved.

(Second Embodiment)
FIG. 5 is a block diagram showing a schematic configuration of the driving apparatus according to the second embodiment of the present invention. FIG. 6 is a block diagram showing a schematic configuration of a detection unit (phase detection unit) of the driving apparatus according to the second embodiment of the present invention. Next, with reference to FIG. 5 and FIG. 6, the structure of the drive device by 2nd Embodiment of this invention is demonstrated. In addition, in each figure, the same code | symbol is attached | subjected to a corresponding component, and the overlapping description is abbreviate | omitted.

  In the second embodiment, unlike the first embodiment, the detection unit 40 detects the phase difference between the detection signal output unit 140 that outputs the detection signal and the detection signal and the output current value. Part 150. In addition, the drive unit 20 applies (outputs) a drive voltage as a drive signal to the polymer actuator 10 and outputs the same drive signal (drive voltage) as the drive signal output to the polymer actuator 10 to the control unit 160. Output. However, in the second embodiment, the drive signal from the drive unit 20 is configured not to be directly input to the detection unit 40. That is, in the second embodiment, unlike the first embodiment, the detection unit 40 is configured to generate the determination signal using the detection signal instead of the drive signal.

  Further, the detection signal from the detection signal output unit 140 is superimposed on the drive signal from the drive unit 20 and then input to the polymer actuator 10. That is, in the second embodiment, a superimposed signal in which a drive signal (drive voltage) and a detection signal are superimposed is applied to the polymer actuator 10. The detection signal from the detection signal output unit 140 is also input to the phase detection unit 150.

  The phase detection unit 150 of the detection unit 40 generates a determination signal for determining the insulation state of the polymer actuator 10 from the output current value from the polymer actuator 10 and the detection signal from the detection signal output unit 140. . Further, as shown in FIG. 6, the phase detection unit 150 includes AC couplings 151 and 153, comparators 152 and 154, an XOR logic gate 155, and a low-pass filter (LPF) 156, and the AC coupling 151 Is supplied with a detection signal, and the AC coupling 153 is supplied with an output current value. The detection signal input to the AC coupling 151 is input to one input terminal of the XOR logic gate 155 via the comparator 152. On the other hand, the output current value input to the AC coupling 153 is input to the other input terminal of the XOR logic gate 155 via the comparator 154. The output terminal of the XOR logic gate 155 is connected to the low-pass filter 156, and a signal passing through the XOR logic gate 155 is output to the control unit 160 as the determination signal through the low-pass filter 156.

  As shown in FIG. 5, the control unit 160 has a function of calculating a criterion value for determining the insulation state of the polymer actuator 10 based on a drive signal (drive voltage) from the drive unit 20. is doing. The control unit 160 determines the insulation state of the polymer actuator 10 from the calculated determination reference value and the determination signal from the detection unit 40 (phase detection unit 150). When it is determined that the polymer actuator 10 is in a dielectric breakdown state, the switch unit 30 is instructed to shut off the drive signal, and energization of the polymer actuator 10 is stopped.

  7 to 15 are views for explaining the operation of the driving apparatus according to the second embodiment of the present invention. FIG. 7A shows an example of the waveform of the drive signal (drive voltage) output from the drive unit, and FIG. 7B shows the waveform of the output signal output from the detection signal output unit. An example is shown, and FIG. 7C shows an example of a waveform of a signal obtained by superimposing the waveform of the drive signal and the waveform of the detection signal. Next, the operation of the driving apparatus according to the second embodiment of the present invention will be described with reference to FIGS.

  A drive signal having a waveform as shown in FIG. 7A, for example, is output from the drive unit 20, and a waveform as shown in FIG. 7B is detected from the detection signal output unit 140 (see FIG. 5), for example. A signal is output. The drive signal from the drive unit 20 is superimposed on the detection signal from the detection signal output unit 140 (see FIG. 5) to become a superimposed signal as shown in FIG. 7C, for example, as shown in FIG. A superimposed signal is applied to the polymer actuator 10. At this time, the detection signal from the detection signal output unit 140 is also output to the phase detection unit 150 (see FIG. 5).

  In view of safety, the detection signal preferably uses a frequency band that is higher by about two digits than the driving frequency of the polymer actuator 10 (frequency of the driving signal). Since such a detection signal makes it difficult for the polymer actuator 10 to respond, the polymer actuator 10 (displacement layer) does not affect the operation of the polymer actuator 10 even when it is superimposed on the drive signal. It is possible to detect the insulation state.

  On the other hand, when a drive signal is input to the polymer actuator 10, an output current value is output, and this output current value is input to the phase detector 150 (see FIG. 5) of the detector 40. That is, the detection signal from the detection signal output unit 140 (see FIG. 5) and the output current value from the polymer actuator 10 are input to the phase detection unit 150 (see FIG. 5) of the detection unit 40. Since the superposed signal on which the detection signal is superimposed is input to the polymer actuator 10, the output current value also has a waveform on which the detection signal is superimposed as shown in FIG.

  As shown in FIG. 6, the DC signal is removed from the detection signal input to the detection unit 40 (phase detection unit 150) through the AC coupling 151. Thereafter, the signal passes through the comparator 152 and is converted into a binary signal indicating the presence or absence of a current corresponding to the input / output of the drive signal. Specifically, as shown in FIG. 9, when the value of the detection signal after passing through the AC coupling 151 (see FIG. 6) is larger than the predetermined reference value F, the H level and the AC coupling 151 ( When the value of the detection signal after passing through FIG. 6 is small, it is converted into a binary signal (X) that becomes L level. The converted binary signal (X) is input to the XOR logic gate 155 (see FIG. 6).

  The output current value input to the detection unit 40 (phase detection unit 150) passes through the AC coupling 153 (see FIG. 6) to remove the DC component and is converted into a waveform as shown in FIG. Thereafter, the signal passes through the comparator 154 (see FIG. 6) and is converted into a binary signal indicating the presence / absence of a current corresponding to the input / output of the drive signal. Specifically, as shown in FIG. 11, when the value of the current value after passing through the AC coupling 153 (see FIG. 6) is larger than the predetermined reference value F, the H level and the AC coupling 153 ( When the value of the current value after passing through FIG. 6 is small, it is converted into a binary signal (Y) that becomes L level. Then, the converted binary signal (Y) is input to the XOR logic gate 155 (see FIG. 6).

  Subsequently, the XOR logic gate 155 performs an XOR operation of both signals, and as shown in FIG. 12, a phase difference signal indicating a phase difference between the two signals is generated. Thereafter, the phase difference signal is passed through a low-pass filter 156 (see FIG. 6) to generate a signal indicating the degree of phase shift with respect to time, and this signal is output to the control unit 160 as a determination signal.

  The controller 160 first determines the insulation state of the polymer actuator 10 (the displacement layer 5 (see FIG. 2)) based on the determination signal. The determination signal is a phase difference between the input voltage (detection signal superimposed on the drive voltage) and the output current (detection signal superimposed on the output current value) at that time, but the polymer actuator 10 (displacement layer 5). In the state where no dielectric breakdown has occurred, the capacitance and the insulation resistance in the displacement layer 5 have predetermined values, and the phase difference also has a value corresponding thereto. However, during the driving operation of the polymer actuator 10, the volume of the displacement layer 5 (dielectric polymer) changes according to the driving signal (driving voltage), and the capacitance also changes accordingly. For this reason, the current value output from the polymer actuator 10 also changes.

  Therefore, in the second embodiment, the control unit 160 calculates a value for a determination criterion in a state where dielectric breakdown has not occurred, according to the input drive signal (drive voltage). The determination reference value changes according to the change of the drive signal (drive voltage).

  Here, since the displacement layer 5 (see FIG. 2) of the polymer actuator 10 can be expressed as an equivalent circuit in a configuration in which a capacitor component and a resistance component are connected in parallel, the CR parallel circuit shown in FIG. 13 and FIG. The phase shift between both the detection signal and the output current value will be described with reference to the vector diagram shown in FIG.

As shown in FIGS. 13 and 14, a current I _R flows through the resistor 205b, and a current I _C flows through the capacitor 205a. When the voltage V is used as a reference, the current I _{C of the} capacitor 205a advances in phase by 90 ° with respect to the current I _{R of the} resistor 205b. Therefore, the entire current I (corresponding to the displacement layer current) is I _{a in} FIG. become that way. An angle α formed by the current I (I _a ) and the current I _R corresponds to a phase difference in a state where no dielectric breakdown occurs.

When dielectric breakdown occurs in the displacement layer 5 (see FIG. 2), the insulation resistance (resistance component 5b) decreases according to the degree of damage, and accordingly, the leakage current flowing through the resistance component 5b increases. For this reason, in FIG. 14, the resistance value R of the resistor 205b (see FIG. 13) decreases, so that the current I _R (= V / R) increases. In other words, a state from the state of I _R is A1 A2. Then, the current I also changes from the B1 state (I _a ) to the B2 state (I _b ), and the phase difference (angle α) decreases. That is, when dielectric breakdown occurs in the polymer actuator 10, the degree of phase shift changes.

Further, when the volume of the displacement layer 5 (see FIG. 2) is changed by driving the polymer actuator 10, the capacitance C changes, so that I _C (= ωCV) in FIG. 14 also changes. For this reason, as described above, the control unit 160 calculates a value for determination reference according to the drive signal (drive voltage).

  Then, the control unit 160 compares the calculated determination reference value with the determination signal from the detection unit 40, and the determination signal exceeds (below) the determination reference (determination reference value). If it is, it will be judged that the leakage current has increased and the dielectric breakdown has occurred.

  Specifically, the determination signal that has passed through the low-pass filter 156 (see FIG. 6) is monitored as a signal indicating the degree of phase shift with respect to time, for example, as shown in FIG. When dielectric breakdown occurs, the leakage current increases and the phase difference decreases, so the degree of phase shift decreases. When the determination signal falls below the determination criterion, it is determined that dielectric breakdown has occurred. However, more accurate control is possible by taking into account error factors such as measurement errors and making judgments on the value of the criterion + error. Further, since the phase difference (the degree of phase shift) also changes due to a change in drive voltage (change in capacitance), the determination criterion also changes according to the drive voltage (drive signal).

  When the control unit 160 determines that dielectric breakdown has occurred (determined to be in a dielectric breakdown state), the control unit 160 issues an instruction to cut off the drive signal to the switch unit 30. Cut off the actual signal. By blocking this signal, the energization to the polymer actuator 10 is stopped, and damage due to further driving operation is prevented.

  Thus, in the drive device according to the second embodiment, the detection unit 40 includes the detection signal output unit 140 that outputs the detection signal to be superimposed on the drive signal, and the determination signal is output from the detection signal and the output current value. By configuring so as to generate, a determination signal corresponding to the drive signal can be easily generated, and the insulation state in the operating state of the polymer actuator 10 can be accurately determined.

  Other effects of the second embodiment are the same as those of the first embodiment.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

DESCRIPTION OF SYMBOLS 5 Displacement layer 5a Capacitor component 5b Resistance component 6, 7 Electrode layer 6a, 7a Resistance component 10 Polymer actuator 11 Displacement layer 20 Drive part 30 Switch part 40 Detection part 41, 151, 153 AC coupling 42 A / D conversion part 43 Integration unit 50, 160 Control unit 140 Detection signal output unit 150 Phase detection unit 152, 154 Comparator 155 XOR logic gate 156 Low-pass filter

Claims (4)

A polymer actuator including a displacement layer made of a dielectric elastomer;
A drive unit that outputs a drive signal for driving the polymer actuator;
A detection unit that generates a determination signal according to the drive signal from an output current value that is output when the polymer actuator is driven;
A control unit for determining an insulation state of the displacement layer from the drive signal and the determination signal;
Based on an instruction from the control unit, a switch unit that switches between a state of outputting the drive signal to the polymer actuator and a state of blocking the drive signal,
When it is determined that the displacement layer is in a dielectric breakdown state, the control unit issues an instruction to block the drive signal to the switch unit and stops energization of the polymer actuator. , Drive device.   The drive device according to claim 1, wherein the detection unit generates the determination signal from the drive signal and the output current value.   The detection unit includes a detection signal output unit that outputs a detection signal to be superimposed on the drive signal, and generates the determination signal from the detection signal and the output current value. The drive device according to 1.   The drive device according to claim 3, wherein the detection signal is an AC signal having a frequency two orders of magnitude higher than the frequency of the drive signal.

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