WO2020044868A1 - Robot hand - Google Patents

Abstract

This robot hand (10) manipulates an article (A) by means of fingers (13). The robot hand (10) is provided with: actuators which are disposed in a position on the fingers (13) where an outside force from the article (A) acts, and which expand and contract in the direction of action of the outside force from the article (A); and a control unit which controls said actuators. The actuators are DEAs (16) which comprise a dielectric layer and an electrode layer laminated in the direction of action of the outside force from the article (A). On the basis of the electrostatic capacity of the DEAs (16), the control unit (15) controls the DEAs (16) such that the outside forces acting on the DEAs (16) approach a target value.

Description

Robot hand

The present disclosure relates to a robot hand that operates an article with a finger.

Patent Literature 1 discloses a robot hand including a palm part, a plurality of finger parts provided on the palm part, a joint mechanism that allows the finger part to bend freely, and a drive unit that drives the joint mechanism. . The robot hand of Patent Literature 1 is provided with two or more pressure-sensitive elements on a specific surface of a finger in order to grip an object with a specific surface of a finger parallel to a gripping surface of the item. The posture of the finger is controlled so that the forces detected by all the pressure-sensitive elements when the article is brought into contact with the specific surface of the finger are approximately the same.

Patent Document 2 discloses a microtweezer provided with a pair of supports. A holding portion that is deformed by applying a voltage is provided at the tip of each support. The micro tweezers disclosed in Patent Literature 2 can control the pressure applied to an article held by the micro tweezers by adjusting the voltage applied to the holding unit.

Patent No. 5267213 JP 2006-326716 A

In order to improve the accuracy of manipulating the article with the finger of the robot hand, it is important to appropriately control the force generated between the finger and the article. As a method of controlling a force generated between a finger and an article, a holding unit of Patent Document 2 is applied to a finger of a robot hand of Patent Document 1, and the holding is performed based on a force detected by a pressure-sensitive element. It is conceivable to deform the part. However, in this case, there is a problem that the structure and wiring of the finger part are complicated.

The purpose of the present disclosure is to simplify the configuration of a robot hand that can control a force generated between a finger and an article.

A robot hand for solving the above-mentioned problems is a robot hand including at least one finger unit and operating an article with the finger unit, the robot hand being provided at a portion of the finger unit where an external force from the article acts, and An actuator that expands and contracts in a direction in which an external force from the actuator acts, and a control unit that controls the actuator. The actuator can detect an external force acting on the actuator from the article based on a specific parameter of the actuator. The control unit controls the actuator based on the specific parameter so that an external force acting on the actuator approaches a target value.

For example, the actuator is a dielectric elastomer actuator in which a dielectric layer and an electrode layer are laminated in a direction in which an external force from the article acts, and the specific parameter is a value based on capacitance or capacitance, The control unit controls the actuator based on a voltage applied to the actuator and a measured capacitance of the actuator or a value based on the capacitance.

According to the above configuration, the dielectric elastomer actuator provided on the finger portion functions as an actuator for adjusting the force generated between the finger portion and the article, and also detects the force generated between the finger portion and the article. Also functions as a unit. Therefore, there is no need to provide a detection unit such as a pressure-sensitive element separately from the dielectric elastomer actuator. Therefore, the configuration of the robot hand can be simplified by omitting the detection unit itself, the wiring connected to the detection unit, and the like, as compared with the case where the detection unit is separately provided.

In the robot hand, the control unit applies an initial voltage for compressing the actuator before the finger and the article come into contact with each other, and moves the finger to move the finger and the article. After the contact, it is preferable that the voltage applied to the actuator is reduced to relax the compressed state of the actuator.

According to the above configuration, the external force acting on the dielectric elastomer actuator can be made closer to the target value by the one-way process of decreasing the voltage applied to the dielectric elastomer actuator. Also, the external force acting on the dielectric elastomer actuator is increased to approach the target value. Therefore, an excessive force acting on the article due to the external force acting on the dielectric elastomer actuator greatly exceeding the target value is suppressed.

In the robot hand, it is preferable that the actuator is provided at a portion of the finger portion that comes into contact with an article.
According to the above configuration, it is possible to reduce the impact at the time of contact between the finger and the article based on the elasticity of the dielectric elastomer actuator. Further, since the surface shape of the dielectric elastomer actuator is elastically deformed along the surface shape of the article, a contact area between the article and the dielectric elastomer actuator can be secured, and the contact state between the article and the finger portion is stabilized.

In the robot hand, it is preferable that the target value is set according to a type of the article.
According to the above configuration, even when a plurality of types of articles are targeted, the articles can be operated with an appropriate force according to the type of the article.

In the above robot hand, the at least one finger is preferably two or more fingers, and more preferably three or more fingers.
According to the above configuration, when the article is grasped, the article can be stably grasped by independently adjusting the grasping force at a plurality of contact points with the article.

According to the present disclosure, the configuration of the robot hand that can control the force generated between the finger and the article can be simplified.

The schematic diagram of a robot hand. FIG. 2 is a schematic view of a dielectric elastomer actuator. FIG. 4 is a diagram showing a relationship between a control unit and a dielectric elastomer actuator. 4 is a graph showing a relationship between an applied voltage, a capacitance, and an external force in a dielectric elastomer actuator. 5 is a flowchart of control for gripping an article. 9 is a flowchart of control for maintaining a state in which an article is held.

Hereinafter, an embodiment of the robot hand will be described.
As shown in FIG. 1, the robot hand 10 includes a main body 12 connected to the arm 11 and three fingers 13 extending from the main body 12 and operating the article A. Each finger 13 has a bendable joint mechanism. The main unit 12 is provided with a drive unit 14 such as a motor for driving a joint mechanism of the finger unit 13 and a control unit 15 for controlling the drive unit 14.

誘 電 A dielectric elastomer actuator 16 (DEA: Dielectric Elastomer Actuator) that expands and contracts in the direction toward the inside and outside of the finger 13 is provided on the inner surface of the tip of each finger 13. In the present embodiment, the DEA 16 constitutes an actuator having a self-sensing function.

As shown in FIG. 2, the DEA 16 has a combination of a sheet-like dielectric layer 20 made of a dielectric elastomer and a positive electrode 21 and a negative electrode 22 as electrode layers disposed on both sides in the thickness direction of the dielectric layer 20. It is a multilayer structure in which a plurality of layers are stacked. An insulating layer 23 is laminated on the outermost layer of the DEA 16.

In the DEA 16, when a DC voltage is applied between the positive electrode 21 and the negative electrode 22, the dielectric layer 20 is compressed in the thickness direction and along the surface of the dielectric layer 20 according to the magnitude of the applied voltage. Deform to stretch in the direction As shown in FIG. 1, the DEA 16 is attached to the finger 13 such that the laminating direction of the plurality of layers constituting the dielectric elastomer actuator coincides with the direction from the outside to the inside of the finger 13.

誘 電 The dielectric elastomer constituting the dielectric layer 20 is not particularly limited, and a known dielectric elastomer used for DEA can be used. Examples of the dielectric elastomer include a crosslinked polyrotaxane, silicone elastomer, acrylic elastomer, and urethane elastomer. One of these dielectric elastomers may be used, or a plurality of them may be used in combination. The thickness of the dielectric layer 20 is, for example, 20 to 200 μm.

材料 Examples of the material forming the positive electrode 21 and the negative electrode 22 include a conductive elastomer, carbon nanotube, Ketjen Black (registered trademark), and a metal deposition film. Examples of the conductive elastomer include a conductive elastomer containing an insulating polymer and a conductive filler.

Examples of the insulating polymer include cross-linked polyrotaxane, silicone elastomer, acrylic elastomer, and urethane elastomer. One of these insulating polymers may be used, or a plurality of them may be used in combination. Examples of the conductive filler include Ketjen Black (registered trademark), carbon black, and metal particles. Examples of the metal particles include copper and silver. One of these conductive fillers may be used, or a plurality of them may be used in combination. The thickness of the positive electrode 21 and the negative electrode 22 is, for example, 10 to 100 μm.

絶 縁 The insulating elastomer constituting the insulating layer 23 is not particularly limited, and a known insulating elastomer used for an insulating portion of a known DEA can be used. Examples of the insulating elastomer include a crosslinked polyrotaxane, a silicone elastomer, an acrylic elastomer, and a urethane elastomer. One of these insulating elastomers may be used, or a plurality of them may be used in combination. The thickness of the insulating layer 23 is, for example, 10 to 100 μm.

(3) As shown in FIG. 3, the control unit 15 controls the voltage applied to the DEA 16 from a power supply (not shown) such as a battery. The control unit 15 includes one or more dedicated processors such as 1) one or more processors that operate according to a computer program (software) and 2) an application specific integrated circuit (ASIC) that performs at least a part of various processes. Or a circuit including 3) a combination thereof. The processor includes a CPU and a memory such as a RAM and a ROM, and the memory stores a program code or a command configured to cause the CPU to execute a process. Memory or computer readable media includes any available media that can be accessed by a general purpose or special purpose computer. When the control unit 15 changes the applied voltage to the DEA 16, the DEA 16 is deformed into a shape corresponding to the magnitude of the applied voltage.

{Circle around (4)} The control unit 15 measures the capacitance of the DEA 16 by applying an AC voltage sufficiently smaller than the applied voltage to the applied voltage. Then, the control unit 15 controls the applied voltage to the DEA 16 based on the relationship between the applied voltage to the DEA 16 and the measured capacitance of the DEA 16 so that the external force acting on the DEA 16 approaches a predetermined target value.

静電 The capacitance of the DEA 16 is a parameter that is inversely proportional to the distance between the electrodes of the DEA 16 and proportional to the area of the electrodes (opposed area), and varies according to the shape of the DEA 16. Therefore, when a voltage is applied to the DEA 16 and the DEA 16 is compressed in the thickness direction of the dielectric layer 20, the capacitance of the DEA 16 also increases. Therefore, as shown by the change curve L1 in the graph of FIG. 4, a correlation is established between the voltage applied to the DEA 16 and the capacitance, as one increases and the other increases.

Similarly, when an external force acts on the DEA 16 to compress the DEA 16 in the thickness direction of the dielectric layer 20, the capacitance of the DEA 16 increases. Therefore, even when the voltage applied to the DEA 16 is the same, the capacitance of the DEA 16 when no external force is acting on the DEA 16 and the capacitance of the DEA 16 when an external force is acting on the DEA 16 There is a difference between

4 shows the relationship between the applied voltage and the capacitance of the DEA 16 when a constant external force (a target value of the external force described later) is acting on the DEA 16. The change curve L2 is shifted from the change curve L1 in a state where no external force acts on the DEA 16 in a direction in which the capacitance increases by an amount corresponding to the magnitude of the external force acting on the DEA 16.

Therefore, the difference in capacitance based on the presence or absence of the external force acting on the DEA 16 can be regarded as a parameter indicating the magnitude of the external force acting on the DEA 16. In the present embodiment, the external force acting on the DEA 16 of the finger portion 13 from the article A when the article A is brought into contact with the robot hand 10 is estimated from the voltage applied to the DEA 16 and the capacitance of the DEA 16.

Here, the external force acting on the DEA 16 is a force generated between the finger 13 and the object, and is a reaction force (force sense) acting on the DEA 16 from the object when the finger 13 presses the object. Information). Therefore, when the target is gripped by the finger 13, the external force acting on the DEA 16 corresponds to the gripping force of the finger 13 gripping the target.

制 御 As shown in FIG. 3, the control unit 15 includes a storage unit 15a. The storage unit 15a stores a reference capacitance C0 and a target capacitance Ct. The reference capacitance C0 is a capacitance in a state where no external force acts on the DEA 16 (a state where the article A or the like is not in contact with the finger portion 13), and as shown in a change curve L1 in FIG. It is stored as a relational expression between the voltage applied to and the capacitance. The reference capacitance C0 can be obtained by simulation or preliminary measurement.

The target capacitance Ct is a value obtained by converting a target value of the external force acting on the DEA 16 into a capacitance. As shown in the graph of FIG. 4, the difference between the change curve L1 when no external force is acting on the DEA 16 and the change curve L2 when a target value of external force is acting on the DEA 16 is as follows. It corresponds to the target capacitance Ct.

The target capacitance Ct is set for each type of the article A according to the characteristics (for example, hardness and shape) of the article A to be operated. The target capacitance Ct may be given as a function of the applied voltage, may indicate a specific value approximating the target capacitance Ct, or may be a value in which a specific range is added thereto. There may be. The method for setting the target capacitance Ct is not particularly limited. For example, the determination may be performed by a user's input, or the type of the article A may be determined using a detection unit such as an image sensor, and the article A may be determined from among the plurality of target capacitances Ct stored in the storage unit 15a. Control may be performed so as to select the target capacitance Ct according to the type.

Next, the control for executing the operation of gripping the article A using the robot hand 10 will be described based on the flowchart of FIG. Here, as shown in FIG. 1, control from a state in which the robot hand 10 and the article A are positioned so that the article A can be gripped by moving the finger portion 13 of the robot hand 10 inward will be described. I do.

First, the control unit 15 applies the initial voltage V0 to the DEA 16 of the finger unit 13 to bring the DEA 16 into a compressed state (step S1). The initial voltage V0 is a voltage necessary for compressing the DEA 16 to a maximum compression state set in advance as an upper limit in the compression direction of the DEA 16 in a state where no external force acts on the DEA 16.

Thereafter, the control unit 15 controls the driving unit 14 to move the finger units 13 inward so as to close the hands, and to bring the DEA 16 provided on each finger unit 13 into contact with the article A (step S2). . When the DEA 16 comes into contact with the article A, an external force from the article A acts on the DEA 16, so that the capacitance of the DEA 16 increases from the reference capacitance C0 at the initial voltage V0. The control unit 15 measures the capacitance of the DEA 16 at a predetermined cycle, and based on detecting that the amount of increase from the reference capacitance C0 exceeds a preset specified value, the finger unit 13 Stop moving.

Next, the control unit 15 determines the current measured value Cm of the capacitance of the DEA 16 and the reference capacitance at the current applied voltage (initial voltage V0) as external force parameters corresponding to the external force acting on the DEA 16 from the article A. The capacitance difference Cd from C0 (= Cm-C0) is calculated (step S3). Then, the control unit 15 determines whether or not the capacitance difference Cd is smaller than the target capacitance Ct (Step S4).

In step S4, when the capacitance difference Cd is smaller than the target capacitance Ct (YES), the control unit 15 subtracts a predetermined amount from the voltage applied to the DEA 16 to the current applied voltage. The voltage is decreased to the applied voltage Vd (step S5). When the capacitance difference Cd is smaller than the target capacitance Ct, it means that the gripping force is insufficient. Therefore, the gripping force is increased by lowering the applied voltage to the DEA 16 to relax the compressed state of the DEA 16.

In a state where the DEA 16 and the article A are in contact with each other and the DEA 16 is sandwiched between the attachment portion of the DEA 16 in the finger portion 13 and the article A, even if the voltage applied to the DEA 16 is changed, the thickness of the DEA 16 is Hardly change. Therefore, when the voltage applied to the DEA 16 is decreased, as indicated by the left arrow in FIG. 4, only the applied voltage is decreased without changing the capacitance. Thereby, the external force (capacitance difference Cd) acting on the DEA 16 from the article A can be gradually increased toward the target value (target capacitance Ct).

の 後 After step S5, the process returns to step S3. In the second and subsequent steps S3, the capacitance difference Cd is calculated using the reference capacitance C0 at the current applied voltage Vd. Steps S3 to S5 are repeated until the capacitance difference Cd reaches the target capacitance Ct, and the applied voltage is reduced to increase the gripping force.

If the capacitance difference Cd is not smaller than the target capacitance Ct in step S4 (NO), the control unit 15 maintains the voltage applied to the DEA 16. Thereby, the gripping force on the article A can be finely adjusted to the target gripping force. Then, a predetermined operation on the article A, such as conveying the article A, is executed. The above steps S1 to S5 are executed independently for the DEA 16 provided on each finger 13.

Next, the control for maintaining the state where the article A is gripped with the target gripping force will be described with reference to the flowchart of FIG. The control unit 15 repeatedly executes Steps S11 to S15 described below at a predetermined cycle while holding the article A.

The control unit 15 calculates a capacitance difference Cd (= Cm−C0) between the current measured value Cm of the capacitance of the DEA 16 and the reference capacitance C0 at the current applied voltage (step S11). Then, the control unit 15 determines whether the capacitance difference Cd is less than the target capacitance Ct (Step S12). In step S12, when the capacitance difference Cd is smaller than the target capacitance Ct (YES), the control unit 15 subtracts a predetermined amount from the voltage applied to the DEA 16 to the current applied voltage. The voltage is decreased to the applied voltage Vd (step S13).

The fact that the capacitance difference Cd is smaller than the target capacitance Ct means that the gripping force is insufficient due to some cause (for example, vibration or change in posture during conveyance). Therefore, the gripping force is increased by lowering the applied voltage to the DEA 16 to relax the compressed state of the DEA 16. After step S13, the process returns to step S11.

As shown by the leftward arrow in FIG. 4, when the applied voltage to the DEA 16 is decreased, only the applied voltage is decreased without changing the capacitance, whereby the external force ( The capacitance difference Cd) can be gradually increased toward the target value (the target capacitance Ct).

If the capacitance difference Cd is not less than the target capacitance Ct in step S12 (NO), the control unit 15 determines whether the capacitance difference Cd exceeds the target capacitance Ct (step S12). S14). In step S14, when the capacitance difference Cd exceeds the target capacitance Ct (YES), the control unit 15 adds the voltage applied to the DEA 16 to the current applied voltage by a predetermined amount set in advance. The voltage is increased to the applied voltage Vu (step S15).

The fact that the capacitance difference Cd exceeds the target capacitance Ct means that the gripping force is in an excessive state due to some cause (for example, vibration or posture change during conveyance). Therefore, the gripping force is reduced by increasing the voltage applied to the DEA 16 to make the DEA 16 more compressed. After step S15, the process returns to step S11.

As shown by the rightward arrow in FIG. 4, when the applied voltage to the DEA 16 is increased, only the applied voltage is increased without changing the capacitance, whereby the external force ( The capacitance difference Cd) can be gradually reduced toward the target value (target capacitance Ct).

If the capacitance difference Cd does not exceed the target capacitance Ct in step S14 (NO), the control unit 15 maintains the voltage applied to the DEA 16. Thereby, the state where the article A is gripped with the target gripping force is maintained. The above steps S11 to S15 are executed independently for the DEA 16 provided on each finger 13.

Next, the operation and effect of the present embodiment will be described.
(1) The robot hand 10 operates the article A by the finger unit 13. The robot hand 10 is provided at a portion of the finger unit 13 where an external force from the article A acts, and includes an actuator that expands and contracts in a direction in which the external force from the article A acts, and a control unit that controls the actuator. . The actuator is a DEA 16 in which a dielectric layer 20 and electrode layers (a positive electrode 21 and a negative electrode 22) are laminated in a direction in which an external force from the article A acts. The control unit 15 controls the DEA 16 based on the capacitance of the DEA 16 so that the external force acting on the DEA 16 approaches a target value.

According to the above configuration, the DEA 16 provided on the finger 13 functions as an actuator for adjusting the force (gripping force) generated between the finger 13 and the article A, and the DEA 16 between the finger 13 and the article A It also functions as a detection unit for detecting the force generated in. Therefore, there is no need to provide a detection unit such as a pressure-sensitive element separately from the DEA 16. Therefore, the configuration of the robot hand 10 can be simplified by omitting the detection unit itself and the wiring and the like connected to the detection unit, as compared with the case where the detection unit is separately provided.

(2) The control unit 15 applies the applied voltage to the DEA 16, the reference capacitance C0 which is the capacitance when the same applied voltage is applied in a state where no external force is applied to the DEA 16, and the measured value of the capacitance The DEA 16 is controlled based on Cm.

According to the above configuration, the external force acting on the DEA 16 can be easily brought close to the target value based on the capacitance of the DEA 16.
(3) The control unit 15 applies the initial voltage V0 that brings the DEA 16 into a preset maximum compression state before the finger unit 13 comes into contact with the article A. Then, after the finger 13 moves and the finger 13 comes into contact with the article A, the applied voltage to the DEA 16 is reduced, so that the compression state of the DEA 16 is relaxed and the external force acting on the DEA 16 is increased.

According to the above configuration, the external force acting on the DEA 16 can be made closer to the target value by the one-way process of decreasing the voltage applied to the DEA 16. Further, the external force acting on the DEA 16 is increased to approach the target value. Therefore, an excessive force acting on the article A due to the external force acting on the DEA 16 greatly exceeding the target value is suppressed.

(4) The DEA 16 is provided at a portion of the finger portion 13 that contacts the article A.
According to the above configuration, the impact at the time of contact between the finger portion 13 and the article A can be reduced based on the elasticity of the DEA 16. Further, since the surface shape of the DEA 16 is elastically deformed along the surface shape of the article A, a contact area between the article A and the DEA 16 can be secured, and the contact state between the article A and the finger 13 is stabilized.

(5) The target value (target capacitance Ct) of the external force acting on the DEA 16 is set according to the type of the article A.
According to the above configuration, even when a plurality of types of articles A are targeted, the articles A can be operated with an appropriate gripping force according to the type of the articles A.

(6) The robot hand 10 includes three fingers 13 each having a DEA 16.
According to the above configuration, when the article A is grasped, the article A can be stably grasped by independently adjusting the grasping force at a plurality of contact points with the article A. For example, when the gripped article A vibrates, the gripping force becomes insufficient at a certain contact point, and the gripping force becomes excessive at another contact point. It can be adjusted to an appropriate gripping force.

The present embodiment can be modified and implemented as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-The configuration such as the shape of the robot hand 10 can be changed as appropriate. For example, the number of fingers 13 of the robot hand 10 may be changed. It is sufficient that the number of the finger portions 13 is one or more. However, when gripping the article A, it is preferable to provide two or more finger portions 13 from the viewpoint of holding stability, and it is preferable to provide three or more finger portions. More preferably, the portion 13 is provided.

The position where the DEA 16 is provided on the finger portion 13 is not limited to the portion that contacts the article A. For example, the DEA 16 is provided in a portion other than the portion that contacts the article A, and the force is transmitted bidirectionally between the portion of the finger portion 13 that contacts the article A and the DEA 16 via a link mechanism or the like. You may. In this case, the DEA 16 is attached so as to extend and contract in a direction in which an external force acts.

Regarding the control when gripping the article A, the processing of steps S11 to S15 of the flowchart of FIG. 6 may be performed instead of the processing of steps S3 to S5 of the flowchart of FIG.
Even if the target value (target capacitance Ct) of the external force acting on the DEA 16 is changed at a predetermined timing (for example, a timing of changing the transport direction or the posture) during a series of steps of operating the article A. Good. For example, while the article A is being gripped, the position and orientation of the gripped article A can be finely adjusted by changing the target value of the external force acting on the DEA 16.

The method of controlling the DEA 16 so that the external force acting on the DEA 16 approaches the target value based on the capacitance of the DEA 16 obtains the capacitance difference Cd, and brings the capacitance difference Cd closer to the target capacitance Ct. The method is not limited to the method of gradually increasing or decreasing the applied voltage as described above, and other methods may be employed.

For example, a relational expression between the voltage applied to the DEA 16 and the capacitance of the DEA 16 when the target external force is acting on the DEA 16 (the value obtained by adding the target capacitance Ct to the reference capacitance C0) (FIG. 4) (Corresponding to the change curve L2) is stored in the storage 15a. Then, based on the measured value Cm of the capacitance of the DEA 16 and the above-mentioned relational expression, an applied voltage having the same value as the measured value Cm in the above-mentioned relational expression is obtained, and the applied voltage is applied to the DEA 16.

The state of the DEA 16 when the finger portion 13 (DEA 16) is brought into contact with the article A is not limited to the preset maximum compressed state, but may be an uncompressed state or the maximum. The compression state may be intermediate between the compression state and the uncompressed state.

· The hardness of the article A may be determined using the self-sensing function of the DEA 16. For example, in a state where the DEA 16 is in contact with the article A, the voltage applied to the DEA 16 is lowered by a predetermined amount, and the hardness of the article A is determined based on the amount of change in the capacitance of the DEA 16 before and after that. I do. When the article A is a soft object, the amount of change in the capacitance of the DEA 16 is increased by extending the DEA 16 toward the article A so as to push the article A. When the article A is a hard object, the DEA 16 It cannot extend to the A side, and the amount of change in the capacitance of the DEA 16 becomes small.

When the configuration for determining the hardness of the article A is employed, the type of the article A is determined based on the determined hardness of the article A, and the plurality of target capacitances Ct stored in the storage unit 15a are determined. It is preferable to select a target capacitance Ct according to the type of the article A from among them. In this case, there is no need to separately provide a detection unit such as an image sensor for determining the type of the article A.

The DEA 16 may be controlled using a value based on the capacitance (for example, a value having a correlation with the capacitance such as a voltage value) instead of the capacitance of the DEA 16 itself.
The actuator having the self-sensing function is not limited to the DEA 16, but may be any actuator that can detect an external force acting on the actuator from the article A based on the specific parameter of the actuator. For example, an electroactive polymer may be used as the actuator.

The operation by the finger unit 13 may be an operation other than the operation of gripping the article A. For example, in a state where the article A is gripped, the control for increasing the gripping force and the control for weakening the gripping force are alternately executed, so that the gripped article A can be slid down by its own weight little by little. In addition, while holding the article A, the control for increasing the gripping force and the control for weakening the gripping force are alternately executed, and the timing is shifted between the plurality of finger portions 13 to shake (vibrate) the gripped article A. )be able to. Further, the present invention can be applied to an operation of turning a sheet such as paper.

A: article, 10: robot hand, 11: arm, 12: body, 13: finger, 14: drive, 15: control, 15a: storage, 16: dielectric elastomer actuator (DEA), 20: dielectric Layers, 21: Positive electrode, 22: Negative electrode.

Claims (7)

1. A robot hand including at least one finger unit and operating an article with the finger unit,
   An actuator that is provided at a portion of the finger portion where an external force from the article acts, and that expands and contracts in a direction in which the external force from the article acts.
   A control unit for controlling the actuator,
   The actuator has a self-sensing function capable of detecting an external force acting on the actuator from the article based on a specific parameter of the actuator,
   The robot hand according to claim 1, wherein the control unit controls the actuator based on the specific parameter such that an external force acting on the actuator approaches a target value.
2. The actuator is a dielectric elastomer actuator in which a dielectric layer and an electrode layer are stacked in a direction in which an external force from the article acts,
   The specific parameter is a capacitance or a value based on the capacitance,
   The robot according to claim 1, wherein the control unit controls the actuator based on a voltage applied to the actuator and a measured capacitance of the actuator or a value based on the capacitance. hand.
3. The controller, before the finger and the article are in contact with each other, applies an initial voltage to compress the actuator, after the finger moves and the finger and the article come into contact with each other, The robot hand according to claim 2, wherein a voltage applied to the actuator is reduced to reduce a compression state of the actuator.
4. (4) The robot hand according to any one of (1) to (3), wherein the actuator is provided at a portion of the finger portion that comes into contact with an article.
5. The robot hand according to any one of claims 1 to 4, wherein the target value is set according to a type of the article.
6. The robot hand according to any one of claims 1 to 5, wherein the at least one finger is two or more fingers.
7. The robot hand according to any one of claims 1 to 5, wherein the at least one finger is three or more fingers.

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