Deformable polymer fiber actuator, sensor device and control device

An actuator that comprises a deformable material, an energy input part, and a characteristics change detection unit. The deformable material is configured with a polymer fiber and, by deforming in response to energy input from the outside, outputs motive power. The energy input part inputs energy to the deformable material. The characteristics change detection unit detects when the deformation characteristic of the deformable material has changed. The actuator also comprises a drive control unit that, by controlling the above-described energy, controls the output of the deformable material. When the characteristic change detection unit detects a change in the deformation characteristic, the drive control unit controls the energy in accordance with the change in the deformation characteristic.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/JP2017/019105 filed on May 23, 2017. This application is based on and claims the benefit of priority from Japanese Patent Application No. 2016-147611 filed on Jul. 27, 2016. The entire disclosures of all of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an actuator, which outputs motive power by deforming a deformable material in accordance with energy inputted from an outside device electrically, photonically, chemically, thermally, by absorption or by other means. The present disclosure further relates to a sensor device, which uses the actuator as a motive power source, and a control device, which controls the actuator.

BACKGROUND ART

As an actuator of this kind, a polymer fiber actuator is known conventionally as disclosed in, for example, patent literature 1. The polymer fiber actuator disclosed in patent literature 1 is a thermally driven type, which is capable of generating twisting or tension operation in accordance with temperature changes generated by electric heating or optical heating.

PRIOR ART LITERATURE

Patent Literature

SUMMARY

The polymer fiber changes its material characteristic by absorbing water component or oil component and swelling. Because of this change in drive characteristic of the actuator, it sometimes becomes impossible to acquire desired actuator characteristics or causes breakage because of lowered strength. In this type of actuators other than the polymer fiber actuator, similar problems are likely to occur in case that a material (water component or oil component in polymer fiber actuator), which changes a deformation characteristic of a deformable material (polymer fiber in polymer fiber actuator), contacts the deformable material from an outside.

The present disclosure addresses the problem described above and has an object of providing an actuator, which uses deformation of a deformable material as a motive power source and properly suppresses a change in a drive characteristic caused by a change in a deformation characteristic of the deformable material. The present disclosure further has objects of providing a sensor device, which uses the actuator as the motive power source, and a control device, which controls the actuator.

For solving the problem described above, an actuator according to the present disclosure comprises a deformable material formed of a polymer fiber to deform and output motive power in accordance with energy input from an outside, an energy input device for inputting the energy to the deformable material, a characteristic change detection unit for detecting a change in the deformation characteristic of the deformable material, and a drive control unit for controlling the output of the deformable material by controlling the energy. The drive control unit controls the energy in accordance with the change in the deformation characteristic, when the characteristic change detection unit detects the change in the deformation characteristic.

Similarly, for solving the problem described above, a sensor device according to the present disclosure comprises a sensor unit for detecting outside information and the actuator capable of changing a posture of the sensor unit.

Further, for solving the problem described above, a control device is provided for controlling an actuator, which includes a deformable material formed of a polymer fiber to deform and output motive power in accordance with energy input from an outside and an energy input device for inputting energy to the deformable material. The control device comprises a characteristic change detection unit for detecting a change in the deformation characteristic of the deformable material and a drive control unit for controlling the output of the deformable material by controlling the energy. The drive control unit controls the energy in accordance with the change in the deformation characteristic, when the characteristic change detection unit detects the change in the deformation characteristic.

With those configurations, when the change in the deformation characteristic of the deformable material is detected, the actuator output is protected from being affected by the change in the deformation characteristic of the deformable material by properly controlling the energy inputted to the deformable material. As a result, it is possible to properly suppress a change in a drive characteristic of the actuator caused by the change in the deformation characteristic of the deformable material.

According to the present disclosure, it is possible to provide an actuator, which properly suppresses a change in a drive characteristic caused by a change in a deformation characteristic of a deformable material in the actuator using the deformation of the deformable material as a motive power source. It is also possible to provide a sensor device, which uses the actuator as the motive power source, and a control device, which controls the actuator.

EMBODIMENT

Embodiments will be described below with reference to accompanying drawings. For easy understanding of the description, same structural components are designated with same reference numerals throughout the drawings thereby to simplify the duplicated description.

An actuator, which is a subject of the present disclosure, is an actuator for outputting motive power by deforming a deformable material in accordance with energy input electrically (e.g., current change), photonically (e.g., strength of irradiated light), chemically (e.g., reversible chemical reaction), thermally (e.g., temperature change), absorption (contraction by water absorption) or by other means. Such an actuator includes, for example, a polymer actuator, a shape-memory alloy, a piezoelectric element and the like. In the following embodiments, a polymer fiber actuator will be described as one example.

First Embodiment

A first embodiment will be described with reference toFIG. 1toFIG. 3. Referring first toFIG. 1, a configuration of a polymer fiber actuator1according to the first embodiment will be described.

The polymer fiber actuator1(actuator) according to the first embodiment is formed in a string shape extending in a predetermined axial direction as shown inFIG. 1and has an axial cross section of a generally circular shape. The polymer fiber actuator1is capable of outputting motive power as an expansion/contraction operation in the axial direction or a twist operation about an axis in accordance with energy input, which is a temperature rise by heating. In the following description, as shown inFIG. 1, a direction of expansion (axial direction) of the polymer fiber actuator1is indicated as an X direction and a predetermined one direction (up-down direction inFIG. 1) among radial directions of a cross section, which is perpendicular to the X direction, is indicated as a Y direction.

As shown inFIG. 1, the polymer fiber actuator1includes a polymer fiber2(deformable material), a heating wire3(energy input part and electrically conductive material) and a control device4.

The polymer fiber2is a motive power source of the polymer fiber actuator1and function as a deformable material, which outputs motive power by deforming in accordance with energy input (temperature rise by heating) from an outside. The polymer fiber2is formed of a bundle of polyamide fibers, which are arranged to extend in the X direction, for example.

The heating wire4is wound spirally about an outer peripheral side of the polymer fiber2. The heating wire3generates heat with current supply and heats the polymer fiber2. That is, the heating wire3functions as an energy input device for performing energy input, which is a temperature rise by heating. The polymer fiber2is capable of performing an expansion/contraction operation in the X direction and a twist operation about the X direction by deforming in accordance with heat inputted from the heating wire3.

The control device4controls deformation of the polymer fiber2, that is, output of the polymer fiber actuator1, by controlling the current supply to the heating wire3.

As described above, the polymer fiber2has a characteristic of changing a physical property by swelling as a result of absorbing water component or oil component in a surrounding environment. With a change in the physical property, a deformation characteristic of the polymer fiber2changes. That is, the amount of deformation of the polymer fiber2varies differently even in case of a temperature rise of the same condition and hence a driving characteristic of the actuator tends to change correspondingly. For this reason, in the first embodiment, the control device4corrects a drive signal (current supply amount) transmitted to the heating wire3from the control device4in accordance with a change in a deformation characteristic of the polymer fiber2caused by swelling so that such a change in the drive characteristic arising from the swelling of the polymer fiber2is prevented. To be in more detail, the control device4corrects the drive signal corresponding to a target output of the polymer fiber2by feedback-controlling the output generated by deformation of the polymer fiber2. The control device4includes, as shown inFIG. 1, a swelling detection unit5(characteristic change detection unit), a drive control unit6, an abnormality detection unit7and a reporting unit8.

The swelling detection unit5detects an occurrence of swelling (change in deformation characteristic) of the polymer fiber2. The swelling detection unit5is capable of estimating presence/absence of occurrence of the swelling based on various information related to a surrounding environment and the polymer fiber2. However, in the first embodiment, the swelling detection unit5detects the occurrence of swelling based on an actual output relative to a target output in controlling driving the polymer fiber2. The swelling detection unit5is electrically connected to, for example, a position sensor9for detecting a displacement amount of the polymer fiber2and an acceleration sensor10for detecting an acceleration in an operation of the polymer fiber2. The swelling detection unit5grasps an actual output of the fibers based on information inputted from those sensors9and10.

The drive control unit6controls the output of the polymer fiber2by controlling energy (heat) inputted from the heating wire3to the polymer fiber2. In the first embodiment, in particular, the drive control unit6controls thermal energy inputted from the heating wire3to the polymer fiber2in accordance with swelling when the swelling detection unit5detects the occurrence of swelling of the polymer fiber2. Specifically, the drive control unit6corrects the drive signal corresponding to the target output of the polymer fiber2by feedback-controlling the output generated by the deformation of the polymer fiber2.

An abnormality detection unit7detects an abnormality of the polymer fiber2. The abnormality of the polymer fiber2detected by the abnormality detection unit7includes a certain abnormality related to the polymer fiber2. For example, even when thermal energy inputted from the heating wire3to the polymer fiber2is controlled, the change in the deformation characteristic caused by swelling cannot be covered and the change in the drive characteristic of the actuator cannot be suppressed. When the abnormality of the polymer fiber2is detected, the abnormality detection unit7outputs its detection result to a reporting part8or stores information related to abnormality detection.

The reporting unit8reports the abnormality of the polymer fiber2detected by the abnormality detection unit7. The reporting unit8is a display device such as a display panel, for example, and may be configured to report the information related to the abnormality to a user of the polymer fiber actuator1by displaying it.

The control device4is physically a microcomputer, which includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory) and the like. All or a part of each function of the control device4is realized by loading application programs stored in the ROM to the RAM and executing it by the CPU, which reads out and writes data in the RAM and the ROM. Further, in case that the polymer fiber actuator1is applied as a vehicle-mounted device, for example, a sensor device20(refer toFIG. 3) using the polymer fiber actuator1as a drive power source is mounted in a vehicle such as an automobile, the control device4may be mounted in a microcomputer (for example, ECU), which is an automotive vehicle component.

The polymer fiber actuator1described above performs the following operations, for example. That is, when the control device4controls the current supply to the heating wire3so that the polymer fiber actuator1outputs a desired operation, a current of a predetermined value flows to the heating wire3and the heating wire3generates heat. Heat generated by the heating wire3is transferred to the polymer fiber2on a surface of which the heating wire3is wound. When the heat transferred from the outer peripheral surface finally reaches a central part of the polymer fiber2and the temperature of its entirety rises, the polymer fiber2deforms in accordance with a temperature rise amount. As a result, the polymer fiber actuator1outputs the motive power in accordance with deformation of the polymer fiber2.

Further, when a swelling detection unit5of the control device4detects an occurrence of swelling of the polymer fiber2during an actuator operation, the polymer fiber actuator1corrects the drive signal for the heating wire3, which corresponds to an actuator target output, so that the drive control unit6covers the change in the deformation characteristic of the polymer fiber2caused by swelling. This correction is occasionally referred to as drive signal correction control below.

One example of detailed processing of the drive signal correction control will be described with reference toFIG. 2. A series of steps in a flowchart of the drive signal correction control shown inFIG. 2is executed by the control device4at every predetermined interval, for example.

At step S11, the polymer fiber actuator1is driven by the drive control unit6. For example, the drive control unit6sets a predetermined target operation (target orbit, target acceleration change and the like) and controls the output by deformation of the polymer fiber2by controlling the heating of the heating wire3in accordance with the drive signal corresponding to the target operation. After finishing the processing of step S11, step S12is executed.

At step12, information is acquired from the position sensor9and the acceleration sensor10by the swelling detection unit5. In the midst of outputting of the operation of the polymer fiber3by the drive control unit6, the swelling detection unit5acquires a deformation amount of the polymer fiber2(for example, expansion/contraction amount in X direction or twist amount about X direction) from the position sensor9and acquires information related to the acceleration in the operation of the polymer fiber2from the acceleration sensor10. After finishing the processing of step S12, step S13is executed.

At step S13, the actuator operation, that is, actual output of the polymer fiber actuator1caused by the deformation of the polymer fiber2, is calculated by the swelling detection unit5based on the sensor information acquired at step S12. After finishing the processing of step S13, step S14is executed.

At step S14, the difference between the actuator operation calculated at step S13and the target operation is calculated by the swelling detection unit5. After finishing the processing of step S14, step S15is executed.

At step S15, it is checked by the swelling detection unit5whether swelling is generated in the polymer fiber2based on the difference between the actuator operation and the target operation calculated at step S14. The swelling detection unit5determines that the deformation characteristic of the polymer fiber2changes and the swelling is generated in the polymer fiber2, when the difference exceeds a predetermined threshold value. The swelling detection unit5outputs a check result related to generation of swelling to the drive control unit6. In case of a determination of step S15that the swelling is present in the polymer fiber2(Yes at step S15), step S16is executed. In case of an opposite determination (No at step S15), the control processing is finished.

At step S16, in accordance with the determination of step S15that the swelling is present in the polymer fiber2, a correction amount is calculated based on the difference between the actuator operation and the target operation calculated at step S14by the drive control unit6so that an adverse effect caused by the swelling of the actuator swelling is suppressed. The drive control unit6may adjust the correction amount in accordance with the difference or set a predetermined correction amount. After finishing the processing of step S16, step S17is executed.

At step S17, the correction mount calculated at step S16is added to the drive signal at the drive control unit6. In the subsequent actuator control, the drive control unit6controls the heating wire3by using the control signal, which is a sum of the drive signal corresponding to the target output of the polymer fiber2and the correction amount. After finishing the processing at step S17, the present control processing is finished.

Next, advantages of the polymer fiber actuator1according to the first embodiment will be described.

The polymer fiber actuator1according to the first embodiment is provided with the polymer fiber2, the heating wire3, the swelling detection unit5and the drive control unit6. The polymer fiber2outputs, as the deformable material, the motive power by deforming in accordance with the energy input (temperature rise by heating) from the outside. The heating wire3inputs, as the energy input device, the energy (heat) to the polymer fiber2. The swelling detection unit5of the control device4detects the change in the deformation characteristic of the polymer fiber2(more in detail, occurrence of swelling of the polymer fiber2by absorption of water component and oil component from the outside). The drive control unit6of the control device4controls the output of the polymer fiber2by controlling the heat of the heating wire3. The drive control unit6controls the heat amount inputted into the polymer fiber2(hereinafter referred to as input heat amount) from the heating wire3in accordance with the change in the deformation characteristic (swelling) when the swelling detection unit5detects the occurrence of swelling of the polymer fiber2.

As described above, the polymer fiber2has a characteristic of changing its physical property by swelling as a result of absorbing the water component and the oil component of the surrounding environment. With the change in the physical property, the deformation characteristic of the polymer fiber2changes. That is, the deformation amount of the polymer fiber2differs even with the temperature rise of the same condition. It is thus likely that the drive characteristic of the actuator also changes. In contrast, the polymer fiber actuator1according to the first embodiment is so configured as described above that the change in the deformation characteristic of the polymer fiber2does not affect the actuator output even in case of the occurrence of swelling of the polymer fiber2by properly controlling the heat amount inputted to the polymer fiber2, when the occurrence of swelling of the polymer fiber2is detected. As a result, it is possible to properly suppress the change in the drive characteristic of the actuator, which arises from the change in the deformation characteristic of the polymer fiber2.

Further, in the polymer fiber actuator1according to the first embodiment, the drive control unit6corrects the input heat amount, which corresponds to the target output of the polymer fiber2, in accordance with the swelling of the polymer fiber2when the swelling detection unit5detects the occurrence of swelling of the polymer fiber2. In more detail, the drive control unit6corrects the drive signal (that is, input heat amount) corresponding to the target output of the polymer fiber2by feedback-controlling the output of the polymer fiber2.

With this configuration, it is possible to properly control the operation of the polymer fiber2so that the actual output of the polymer fiber2attains the target output by properly correcting the input to the polymer fiber2, even under the state that the deformation characteristic of the fiber changes because of swelling.

Further, the polymer fiber actuator1according to the first embodiment is provided with the abnormality detection unit7for detecting the abnormality of the polymer fiber2, which is hard to counter even when the input heat amount is controlled in accordance with the change in the deformation characteristic of the polymer fiber2. With this configuration, the drive control unit6is enabled to recognize accurately a situation, which is not possible to suppress the change in the drive characteristic of the actuator even when the drive signal to the heating wire3is corrected and the input heat amount for the polymer fiber2is corrected in response to the occurrence of swelling.

Further, the polymer fiber actuator1according to the first embodiment is provided with the reporting unit8which reports the abnormality of the polymer fiber2detected by the abnormality detection unit7. With this configuration, it is possible to report promptly the occurrence of abnormality in the polymer fiber2to users and managers of the actuator.

Further, in the polymer fiber actuator1according to the first embodiment, the heating wire3is wound spirally about the outer peripheral side of the polymer fiber2as the energy input part. With this configuration, it is possible to transfer efficiently the heat emitted from the heating wire3to the entirety of the polymer fiber2.

Further, the control device4which is a structural component of the polymer fiber actuator1can provide by itself the similar operation and effect as the entire polymer fiber actuator1by properly controlling the polymer fiber2and the heating wire3by the swelling detection unit5and the drive control unit6and attaining the functions described above.

Next, an exemplary application of the polymer fiber actuator1according to the first embodiment will be described with reference toFIG. 3. As shown inFIG. 3, the polymer fiber actuator1is used as a drive power source of a sensor device20. The sensor device20includes a sensor part21for detecting outside information (heat, temperature, light and the like) and the polymer fiber actuator1which is capable changing a posture of the sensor part21.

The sensor part21is connected to one end part of the polymer fiber actuator1as shown inFIG. 3, for example. The other end part of the polymer fiber actuator1is supported by a fixed member, for example, so that the end part to which the sensor part21is connected is configured to operate more remarkably.

The control device4controls the posture of the sensor part21by controlling the current supply to the heating wire3and thereby controlling the output of the polymer fiber actuator1. The control device4may be configured to feedback-control the posture of the sensor part21by acquiring posture information of the sensor part21and regulating a control amount for the heating wire3in accordance with a difference from a target posture.

It is thus possible to reduce entire size and weight of the sensor device20by applying the polymer fiber actuator1as the drive source for the sensor device20, since the motive power source can be sized small in comparison to a conventional device using a rotary machine such as a motor.

Second Embodiment

A second embodiment will be described with reference toFIG. 4andFIG. 5. A polymer fiber actuator1A according to the second embodiment is different from the actuator according to the first embodiment in a method of correction executed in accordance with the occurrence of swelling of the polymer fiber2.

As shown inFIG. 4, a drive control unit6A provided in a control device4A of the polymer fiber actuator1A calculates a correction value in accordance with swelling of the polymer fiber2during a period of stopping the output of the polymer fiber2when a swelling detection unit5A detects the occurrence of swelling of the polymer fiber2and corrects the drive signal and the input heat amount corresponding to the target output of the polymer fiber2by adding or subtracting the correction amount to or from the drive signal for the heating wire3. In the following description, this correction is referred to as correction value calculation control.

Further, the swelling detection unit5A provided in the control device4A estimates the presence/absence of swelling of the polymer fiber2based on information such as temperature or humidity of the surrounding environment during the operation stop of the polymer fiber2and an electric resistance of the polymer fiber2. The swelling detection unit5A is electrically connected, as shown inFIG. 4, to a temperature sensor11for detecting a temperature of the surrounding environment, a humidity sensor12for detecting a humidity of the surrounding environment and an electric resistance sensor13for detecting an electric resistance of the polymer fiber2and estimates the presence/absence of swelling of the polymer fiber2based on information inputted from those sensors11,12and13.

One example of detailed processing of correction value calculation control in the second embodiment will be described with reference toFIG. 5. A series of steps in a flowchart of the correction amount calculation control shown inFIG. 5is executed by the control device4A at every predetermined interval.

At step S21, it is checked by the drive control unit6A whether the polymer fiber actuator1A is in a stop state. In case of a determination of step S21that the polymer fiber actuator1A is in the stop state (Yes at step S21), step S22is executed. In case of an opposite determination (No at step S21), the control processing is finished.

At step S22, information is acquired from the temperature sensor11, the humidity sensor12and the electric resistance sensor13by the swelling detection unit5A. The swelling detection unit5A acquires the information about the temperature and humidity of the surrounding environment from the temperature sensor11and the humidity sensor12during the period of stopping of the polymer fiber actuator1A and acquires the electric resistance of the polymer fiber2from the electric resistance sensor13. After finishing the processing of step S22, step23is executed.

At step S23, the presence/absence of swelling of the polymer fiber2is estimated by the swelling detection unit5A based on the information acquired at step S22. The swelling detection unit5A estimates the occurrence of swelling of the polymer fiber2, for example, when rises of temperature and humidity of the surrounding environment exceed predetermined values and it is possible to determine that the water component and the like of the surrounding environment is more likely to infiltrate the polymer fiber2. Further, the swelling detection unit5A estimates the occurrence of swelling of the polymer fiber2, when the electric resistance of the polymer fiber2varies in excess of a predetermined range and it is possible to determine that the physical property of the polymer fiber2is changing. After finishing step S23, step S24is executed.

At step S24, it is checked by the drive control unit6A whether the swelling of the polymer fiber2is present under a present state of the polymer fiber actuator1A based on a swelling estimation result of step S23. In case of a determination result indicating the occurrence of swelling (Yes at step S24), step S25is executed. In case of an opposite determination result indicating no occurrence of swelling (No at step S25), the present control processing is finished without execution of correction.

At step S25, the correction value for the drive signal is calculated by the drive control unit6A to eliminate any influence of swelling on the actuator output in response to the determination of occurrence of swelling of the polymer fiber2at step S24. The drive control unit6A can thus estimate, for example, a level of swelling at step S23and regulate the correction amount in accordance with the level of swelling or set a predetermined correction amount. The drive control unit6A controls the heating wire3by using a control signal, which is determined by adding the correction amount to the drive signal corresponding to the target output of the polymer fiber2, in the subsequent actuator control. After finishing the processing of step S25, the present control processing is finished.

According to the polymer fiber actuator1A according to the second embodiment, similarly to the polymer fiber actuator1according to the first embodiment, the actuator output is protected from being affected by the change in the deformation characteristic of the polymer fiber2even in case of the occurrence of swelling of the polymer fiber2by properly controlling the heat amount inputted to the polymer fiber2in response to the detection of occurrence of swelling of the polymer fiber2. As a result, the polymer fiber actuator1A according to the second embodiment provides the similar advantage of the polymer fiber actuator1according to the first embodiment.

Third Embodiment

A third embodiment will be described with reference toFIG. 6andFIG. 7. A polymer fiber actuator1B according to the third embodiment is different from the polymer fiber actuator1according to the first embodiment in that a countermeasure corresponding to the occurrence of swelling of the polymer fiber2is not the correction of the drive signal for the heating wire3but execution of restoration control for restoring the polymer fiber2to the original state.

As shown inFIG. 6, a drive control part6B provided in a control device4B of the polymer fiber actuator1B executes restoration control during stopping of the output of the polymer fiber2when the swelling detection unit5A detects the occurrence of swelling of the polymer fiber2. In the restoration control, by inputting a predetermined heat amount from the heating wire3to the polymer fiber2, the drive control unit6B causes the polymer fiber2to evaporate the water component and the like infiltrated into an inside of the polymer fiber2and restore its original state which is present before the occurrence of swelling of the polymer fiber2. In the following description, this restoration control is referred to as swelling restoration control.

The swelling detection unit5A provided in the control device4B estimates, similarly to the swelling detection unit5A according to the second embodiment, the occurrence of swelling of the polymer fiber2based on the information from the temperature sensor11, the humidity sensor12and the electric resistance sensor13.

One example of detailed processing of the swelling restoration control according to the third embodiment will be described with reference toFIG. 7. A series of steps in a flowchart of the correction amount calculation control shown inFIG. 7is executed by the control device4B at every predetermined interval.

Since contents of processing of steps S31to S34are similar to steps S21to S24ofFIG. 5, respectively, no description will be made.

At step S35, the swelling restoration control is executed by the drive control unit6B to eliminate any influence of swelling on the actuator output in response to a determination of the occurrence of swelling of the polymer fiber2at step S34. In the swelling restoration control, the drive control unit6B outputs a drive signal of a predetermined value for the swelling restoration control for a predetermined period to the heating wire3, for example, during the period of stopping of the polymer fiber2, that is, when the drive signal for driving the polymer fiber actuator1B is not present. The heating wire3generates a predetermined heat amount for the predetermined period in response to inputting of the drive signal. Thus, the polymer fiber2is heated with the predetermined heat amount for the predetermined period to emit at least a portion of the water component and the like and released from swelling. After finishing the processing of step S35, steps S32to S35are repeated until it is determined at step S34that the swelling of the polymer fiber2is not present.

According to the polymer fiber actuator1B according to the third embodiment, the swelling restoration control is executed properly by controlling the heat amount inputted to the polymer fiber2in response to the detection of the occurrence of swelling of the polymer fiber2so that, similarly to the polymer fiber actuator1according to the first embodiment, the actuator output is protected from being affected by the change in the deformation characteristic of the polymer fiber2even in case of the occurrence of swelling of the polymer fiber2. As a result, the polymer fiber actuator1B according to the third embodiment provides the similar advantage of the polymer fiber actuator1according to the first embodiment.

Further, according to the polymer fiber actuator1B according to the third embodiment, the swelling restoration control is executed when the occurrence of swelling of the polymer fiber2is detected. As a result, it is possible to execute the actuator control by maintaining the deformation characteristic of the polymer fiber2always in generally the same state and improve control precision.

The embodiments of the present disclosure are described with reference to detailed examples. However, the present disclosure is not limited to those detailed examples. That is, any other examples resulting from design changes to the detailed examples described above are also included in the scope of the present disclosure as far as the feature of the present disclosure is provided. For example, each element provided in the detailed examples described above and its arrangement, material, condition, shape, size and the like are not limited to the examples but may be altered or modified. Further, each element provided in each embodiment described above may be combined as far as technically possible and such a combination is also included in the present disclosure as far as it has the feature of the present disclosure.

In the embodiments described above, the actuator according to the present disclosure is exemplified as the polymer fiber actuators1,1A and1B. However, the actuator may be exemplified as other types of actuators as far as the deformation of the deformable material (polymer fibers2in the above-described embodiments) is used as the motive power source. In case of other types of actuators, the type of deformable material, the phenomenon of changing a deformation characteristic of a deformable material (swelling of the polymer fiber2in the embodiments described above), the type of substance for changing a deformation characteristic (water component and oil component in the embodiments described above) need be determined properly in correspondence to each actuator. For example, hydrogen is the substance for varying the deformation characteristic in case that the deformable material is a metal.

In the embodiments described above, the heating wire3is exemplified as the energy input device for inputting energy to the deformable material (polymer fibers2). However, differently from the heating wire3, the energy input device may be other electrically conductive materials. For example, an electrically conductive elastomer or plating may be wound about on an outer peripheral surface of the polymer fiber2, which is the deformable material, to cover a portion or all of the outer surface of the polymer fiber2.

According to the first embodiment described above, the swelling detection unit5of the control device4is exemplarily configured to acquire the information about the displacement and acceleration of the polymer fiber2from the position sensor9and the acceleration sensor10during the operation of the polymer fiber2and calculate the actual output of the polymer fiber2based on those sensor information. Without being limited to this configuration, the swelling detection unit5may be configured to use only one of the position sensor9and the acceleration sensor10or use any other information from which the actual output of the polymer fiber2is derivable.

According to the second and third embodiments described above, the swelling detection unit5A of the control devices4A and4B is exemplarily configured to acquire the information about the temperature and humidity of the surrounding environment from the sensor11and the sensor12as well as the electric resistance value of the polymer fiber2from the electric resistance sensor13and estimate the presence/absence of swelling of the polymer fiber2based on those sensor information. However, without being limited to this configuration, the swelling detection unit5A may be configured to use at least one of the temperature sensor11, the humidity sensor12and the electric resistance sensor13or use any other information based on which it is possible to estimate the swelling of the polymer fiber2.

Further, according to the embodiments described above, as one example control method for controlling the energy (heat amount) inputted from the energy input device (heating wire3) to the polymer fiber2when the change in the deformation characteristic (occurrence of swelling) of the deformable material (polymer fiber2), the drive signal correction control, the correction amount calculation control and the restoration control are exemplified according to the first embodiment, the second embodiment and the third embodiment, respectively. However, any other method may be used as far as it is possible to suppress the change in the drive characteristic of the actuator, which arises from the occurrence of swelling of the polymer fiber2. It is also possible to combine any one of the drive signal correction control according to the first embodiment, the correction value calculation control according to the second embodiment and the swelling restoration control according to the third embodiment.

Further, according to the embodiments described above, the energy input device is exemplarily configured to use the electrically conductive material (electric heating wire3) wound about the outer peripheral side of the polymer fiber2, which is the deformable material. However, as far as it is possible to input energy to the deformable material, the energy input device may be configured such that an electrically conductive maternal is embedded in the polymer fiber2to heat the polymer fiber2from the inside, for example.