JP5044668B2 - Robot hand - Google Patents

Description

  The present invention relates to a robot hand attached to the tip of a manipulator in order to hold a target object.

  There is a high demand for robots that perform manual work not only in the manufacturing and service industries but also in the home, and such robots have a robot hand mechanism as an end effect that grips the target object. Yes. For example, in the food and beverage industry, automatic devices such as robots that automatically perform catering and lowering operations are used as a countermeasure for labor shortage. In the handling and lowering work, dishes with different sizes and shapes such as dishes, bowls, cups, trays, chopsticks, spoons, etc. are handled, so in the robot hand mechanism, the target object of any shape can be stabilized from any direction. It is desirable to be able to grip it. However, it is difficult to grip various types of target objects with one robot hand mechanism.

  Patent Document 1 discloses a bullet hand that includes three fingers and changes the driving direction of the fingers by turning the fingers inward and outward (that is, opening and closing in the lateral direction). Yes. This bullet hand can grip the teacup from above or hold the cup from the side. However, since the finger portions cannot be completely opposed to each other, it is difficult to grip an elongated target object such as a chopstick or a spoon. Further, when turning a target object such as a teacup upside down, the three fingers that are not facing the thumb are unstable, and the target object may drop and damage the target object.

  In the bullet hand, one motor is used for the internal rotation and external rotation of the finger portion. In order to maintain the gripping state against the external force acting on the finger when gripping the target object, it is necessary that this motor can generate a large torque, or a powerful speed reducer Needed. Further, a gear is used for the mechanism for changing the driving direction of the finger portion. Since the target object is held by the meshing of the gears, it is weak against the external force acting on the finger part. That is, when a large external force acts on the finger part, there is a problem that the gear teeth are damaged. Further, noise due to gear meshing noise is generated.

  Patent Document 2 discloses a hand mechanism that includes four finger portions, and each finger portion is opened and closed by a wire expansion / contraction operation. In this hand mechanism, the drive direction of each finger is changed by a bare link provided at the base end of the finger. However, the mechanism for changing the driving direction of the finger part is for space saving when the hand is stored, and the driving direction of the finger part cannot be actively changed to hold the target object.

US Pat. No. 7,168,748 JP 2008-126870 A

  As described above, the robot hand mechanism is required to be able to stably hold a target article having an arbitrary shape.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a robot hand mechanism that can stably hold various target objects having different shapes and properties.

  According to one aspect of the present invention, a base, a linear motion mechanism that is disposed opposite to the base and converts the rotational motion of the drive motor into linear motion, and is movable in the first direction by the linear motion mechanism. The first movable part to be supported and one end side of the first movable part are coupled, and the linear motion of the first movable part is converted into a rotational movement around a second direction intersecting the first direction. A first connection mechanism; a first passive rotation unit rotatably supported by the base; and rotated by the first connection mechanism; a first gripping unit attached to the first passive rotation unit; A second connecting mechanism coupled to the other end side of the first movable part and converting the linear motion of the first movable part into a rotational movement around the second direction; and supported rotatably with respect to the base part. , A second passive rotating part rotated by the second connecting mechanism, and the second passive rotating part A robot hand mechanism, wherein the second gripping portion attached, by comprising a are provided.

  According to the present invention, it is possible to stably hold a target object having an arbitrary shape.

It is a figure explaining an example of grasping and release operation of a robot hand mechanism concerning one embodiment of the present invention. It is a figure explaining three operation modes with which the robot hand mechanism shown in FIG. 1 is provided. It is the schematic which shows the structure of the rotation mechanism with which the robot hand mechanism which concerns on this Embodiment is provided. It is the schematic which shows the structure of the 1st modification of the rotation mechanism shown in FIG. It is the schematic which shows the structure of the 2nd modification of the rotating apparatus shown in FIG. (A) is a rotation mechanism operated in the first counter movement mode, (b) is a rotation mechanism operated in the diagonal movement mode, (c) is a rotation mechanism operated in the second counter movement mode, FIG. It is a robot hand mechanism shown in FIG. 1, Comprising: Even if an operation mode is changed, it is a figure explaining the space | interval between finger parts being kept constant. It is a robot hand mechanism which concerns on a comparative example, Comprising: It is a figure explaining that the space | interval between finger parts is changed with the change of operation mode.

  Hereinafter, a robot hand mechanism according to an embodiment of the present invention will be described with reference to the drawings as necessary. Note that, in the following embodiments, the same numbered parts are assumed to perform the same operation, and repeated description is omitted.

  First, with reference to FIG. 1 and FIG. 2, the gripping and releasing operations of the robot hand mechanism according to the present embodiment will be described. The robot hand mechanism according to the present embodiment has four finger portions 101A, 101B, 101C, as shown in the perspective view and the column specified by release in FIG. 101D. In the fingers 101 </ b> A, 101 </ b> B, 101 </ b> C, and 101 </ b> D, the passive rotating unit 104 is supported by the support shaft 103 so as to be rotatable with respect to the base 102. 1 and 2, the rotation mechanism that drives these passive rotation units 104 is omitted, and the rotation mechanism will be described in detail later with reference to FIGS. 3 to 6.

  The output shaft 105 of the passive rotating unit 104 is provided with a parallel link mechanism 106 as a gripping unit that grips the target object. The parallel link mechanism 106 includes a plurality of rotating portions 107 and links as shown in the degree of freedom arrangement drawing and the column specified by release in FIG. 1 and the column specified by the degree of freedom arrangement drawing and gripping. Yes. In the parallel link mechanism 106, one of the plurality of rotating units 107 (for example, a rotating unit coupled to the output shaft 105) is rotationally driven by an actuator (not shown), and the opposing links 108 are maintained in parallel. In the state, the parallel link mechanism 106 is operated. When the rotating unit 107 is driven by the actuator in this manner, as shown in the front view of FIG. 1 and the column specified by gripping, the fingers 101A and 101B (or fingers 101C and 101D) facing each other are displayed. As shown in the front view and the column specified by the release, the tip of the parallel link mechanism 106 comes close to the parallel link mechanism 106 of the opposing finger parts 101A and 101B (or the finger parts 101C and 101D). The tip is separated.

  The robot hand mechanism according to the present embodiment is attached to, for example, a tip portion of a manipulator. When the robot hand mechanism is attached to the distal end portion of the manipulator, the robot hand mechanism is directed to the target object from any direction, for example, from the side or above, so that the target object is located between the parallel link mechanisms 106.

  In this embodiment, in order to simplify the description, the base 102 is formed in a substantially cubic box shape, and the fingers 101A, 101B, 101C, and 101D are formed on one surface of the base (hereinafter referred to as a joint surface). The case where it is provided will be described as an example. From the joint surface of the base portion 102, four support shafts 103 are extended perpendicularly and linearly to the joint surface, and these support shafts 103 are rotatable relative to the base portion 102, respectively. Support. The passive rotation unit 104 is designed so that its rotation axes are parallel to each other. In addition, each passive rotation unit 104 is included on a virtual plane, and is disposed at a position corresponding to a square vertex set on the plane. In other words, the passive rotation unit 104 is disposed apart from the adjacent passive rotation unit 104 by a predetermined distance.

  The grip 106 is not limited to the example of the parallel link mechanism having one degree of freedom as described above, and may be a parallel link mechanism having a plurality of degrees of freedom, or in any other form. There may be.

  Referring to FIG. 2, three operation modes for operating the robot hand mechanism according to the present embodiment are shown. The three operation modes include first and second opposing movement modes and a diagonal movement mode. In the first opposed movement mode, as shown in each column of the first opposed movement mode in FIG. 2, the adjacent finger parts 101A and 101B face each other, and the adjacent finger parts 101C and 101D face each other to select the target object. This is a gripping mode. Further, as shown in each column of the diagonal movement mode in FIG. 2, the diagonal movement mode is such that the fingers 101 </ b> A and 101 </ b> D arranged diagonally face each other and the fingers 101 </ b> B arranged diagonally are arranged. In this mode, 101C faces and grips the target object. Further, as shown in each column of the second opposing movement mode in FIG. 2, the second parallel movement mode is a target in which the adjacent finger parts 101A and 101C face each other and the adjacent finger parts 101B and 101D face each other. In this mode, an object is gripped.

  These three operation modes are switched by simultaneously rotating the four passive rotating units 104 by the rotating mechanism, thereby changing the driving direction of each gripping unit 106. As shown in each column of the plan view of FIG. 2, in the transition from the first opposed movement mode to the diagonal movement mode, each gripper 106 is predetermined by 45 ° around the rotation axis of each passive rotation unit 104 in a predetermined direction. In the transition from the diagonal movement mode to the second opposing movement mode, each gripper 106 is further rotated by 45 ° around the rotation axis of each passive rotation unit 104 in a predetermined direction.

  FIG. 3 schematically shows a configuration of a rotation mechanism that drives the passive rotation unit 104 that rotatably supports the grip unit 106. As shown in FIG. 3, this rotating mechanism is a ball screw as a linear motion mechanism 304 that converts the rotational motion of the drive motor 301 provided in the base 102 into the linear motion of the first and second movable portions 305A and 305B. It has a mechanism. The ball screw mechanism includes a ball screw shaft 304 disposed to face the joint surface of the base portion 102, and first and second ball screw nuts (first and second movable portions) 305A that are screw-engaged with the ball screw shaft 304. , 305B, one end of the ball screw shaft 304 is coupled to the rotation shaft of the drive motor 301 via a coupling (shaft coupling) 302, and the other end is rotatably supported by a bearing portion 303 fixed to the base portion 102. Has been. In the ball screw mechanism, when the ball screw shaft 304 is rotated by the drive motor 301, the first and second ball screw nuts 305A and 305B are moved in a direction along the ball screw shaft 304 (referred to as the x direction).

  When the drive motor 301 is driven and the rotation shaft of the drive motor 301 is rotated, the rotation of the rotation shaft is transmitted to the ball screw shaft 304, and the ball screw shaft 304 is rotated. When the ball screw shaft 304 is rotated, the first and second ball screw nuts 305 </ b> A and 305 </ b> B are moved in a direction corresponding to the rotation direction of the ball screw shaft 304. By selecting the rotation direction of the rotation shaft of the drive motor 301, the rotation direction of the ball screw shaft 304 can be selected, and therefore the moving direction of the first and second ball screw nuts 305A and 305B can be determined. .

  In addition, the moving direction of the first and second ball screw nuts 305A and 305B is determined according to the direction of the thread groove cut in the ball screw shaft 304 as well as the rotation direction of the ball screw shaft 304. In the ball screw shaft 304 of FIG. 3, a first portion 304A between the central portion of the ball screw shaft 304 and the drive motor 301 and a second portion 304B between the central portion of the ball screw shaft 304 and the bearing portion 303 are: The thread groove is cut in the opposite direction. The first ball screw nut 305A is disposed in the first portion 304A, and the second ball screw nut 305B is disposed in the second portion 304B. Accordingly, when the ball screw shaft 304 is rotated by the drive motor 301, the first and second ball screw nuts 305A and 305B are moved in directions opposite to each other, that is, moved toward or away from each other. Is done.

  From both ends of the first ball screw nut 305A, a first link 306 extends linearly along a direction intersecting the ball screw shaft 304 (referred to as the y direction). A pin 307 is provided at the end of the first link 306 so as to protrude in a direction intersecting the x direction and the y direction (referred to as the z direction). The pins 307 are slidably and rotatably supported in elongated holes 309 formed in the second links 308 formed integrally with the output shaft 105 of the passive rotating unit 104, respectively. As an example, the second link 308 is formed in a square shape, that is, has a shape in which a central portion is bent, and is rotated around the z direction with the central portion as a rotation axis. The rotation axis 310 of the second link 308 coincides with the rotation axis of the passive rotation unit 104 that is rotatably supported with respect to the base 102 as described above.

  A long hole 309 for engaging with a pin 307 provided in the first link 306 is formed at one end of the second link 308, and the pin 307 is moved to this length along with the movement of the first ball screw nut 305A. By sliding in the hole 309 (sliding), the distance between the pin 307 and the rotating shaft 310 is changed. Thus, when the pin 307 slides in the elongated hole 309, the angle formed by the first link 306 and the second link 308 is changed, that is, the second link 308 is rotated about the pin 307 as the rotation axis. The In addition, since the rotation shaft 310 of the second link 308 is fixed with respect to the base portion 102, when the first ball screw nut 305 </ b> A is moved in the direction indicated by the arrow A, the finger portion 101 </ b> A has the second link 308. Is rotated in the direction indicated by the arrow RA, and in the finger portion 101C, the second link 308 is rotated in the direction indicated by the arrow RC, that is, in the direction opposite to the finger portion 101A. A gripping portion 106 as shown in FIG. 1 is attached to the other end portion of the second link 308.

  Since the configuration related to the second ball screw nut 305B is the same as that described above in relation to the first ball screw nut 305A, detailed description will be omitted. When the ball screw shaft 304 is rotated by the drive motor 301, the first ball screw nut 305A is moved in the direction indicated by the arrow A, and the second ball screw nut 305B is moved in the direction indicated by the arrow B, ie, the first 1 is moved in the opposite direction to the ball screw nut 305A. When the second ball screw nut 305B is moved in the direction indicated by the arrow B, the second link 308 is rotated in the direction indicated by the arrow RB in the finger portion 101B, and the second link 308 is rotated in the direction indicated by the arrow RB. It is rotated in the direction indicated by the arrow RD, that is, in the direction opposite to the finger 101B.

  Thus, in the robot hand mechanism according to the present embodiment, the driving directions of the plurality of finger portions 101A, 101B, 101C, and 101D are simultaneously changed by the single drive motor 301.

  Instead of an example in which a pin 307 is provided at the tip of the first link 306 and an elongated hole is formed in the second link 308 to engage the pin slidably and rotatably, the second link 308 is provided. A pin may be provided at the end of the first and the first link 306 may be formed with an elongated hole for slidably and rotatably engaging the pin.

Next, the first and second modified examples of the rotating mechanism will be described with reference to FIGS. 4 and 5, and the rotating mechanism according to the first modified example will be described with reference to FIGS. 6 (a) to 6 (c). The operation will be described.
FIG. 4 shows a first modification of the rotating mechanism shown in FIG. In the first modification, the first and second movable portions 305A and 305B are uniaxial linear motions provided on the base portion 102 shown in FIG. 3 so as to be movable in opposite directions as shown in FIG. Supported by mechanism 304. This linear motion mechanism 304 is not limited to the example of the ball screw mechanism shown in FIG. 3, as long as it can convert the rotational motion of the drive motor 301 into the linear motion of the movable portions 305A and 305B. May be used.

  The ball screw mechanism can transmit the output of the drive motor 301 with high efficiency. Therefore, when a ball screw mechanism is used as the linear motion mechanism 304, a low output drive motor can be used as the drive motor 301 for changing the drive direction of the finger portion. Further, even when a strong external force is applied to the finger portions 101A, 101B, 101C, and 101D while the target object is gripped, the gripping postures of the finger portions 101A, 101B, 101C, and 101D are maintained.

  The passive rotation unit 104 of the finger unit 101A is coupled to the first movable unit 305A via the first connection mechanism 401. The first connection mechanism 401 includes a linear motion mechanical element 403 that supports the movable link 402 in a freely movable manner, and a rotary machine element 404 that supports the movable link 402 in a freely rotatable manner. The linear motion machine element 403 is provided between the first link 306 and the movable link 402 fixed to the first movable part 305A, and the rotary machine element 404 is provided between the movable link 402 and the second link 308. The first connection mechanism 401 converts the linear motion of the first movable unit 305A into the rotational motion of the passive rotating unit 104 of the finger unit 101A.

  Similarly, the passive rotation unit 104 of the finger unit 101C is coupled to the first movable unit 305A via the second connection mechanism 401. The second connection mechanism 401 converts the linear motion of the first movable unit 305A into the rotational motion of the passive rotating unit 104 of the finger unit 101C. Similarly, the passive rotation unit 104 of the finger unit 101B is coupled to the second movable unit 305B via the third connection mechanism 401. The third connection mechanism 401 converts the linear motion of the second movable unit 305B into the rotational motion of the passive rotating unit 104 of the finger unit 101B. Furthermore, the passive rotation unit 104 of the finger unit 101D is coupled to the second movable unit 305B via the fourth connection mechanism 401. The fourth connection mechanism 401 converts the linear motion of the second movable unit 305B into the rotational motion of the passive rotating unit 104 of the finger unit 101D.

  In the example shown in FIG. 3, the connection mechanism (including the first to fourth connection mechanisms) 401 is realized by a combination of a pin 307 provided in the first link 306 and a long hole 309 provided in the second link 308. Is done. In another example, the connection mechanism 401 may be realized by a combination of a linear slider and a bearing. In an example in which the connection mechanism 401 is realized by a combination of a linear motion slider and a bearing, a linear rail including a guide rail and a movable link 402 supported on the guide rail so as to be movable in the y direction is provided at the tip of the first link 306. A moving slider is provided. The bearing is disposed between the movable link 402 and the second link 308, and supports the movable link 402 and the second link 308 so as to be rotatable around the z direction. Further, the connection mechanism 401 may exchange the arrangement of the linear motion machine element 403 and the rotary machine element 404 as shown in FIG.

Next, the operation of the rotation mechanism shown in FIG. 3 will be described with reference to FIGS.
6 (a) to 6 (c) respectively show the configuration of the robot hand mechanism operated in the first opposing movement mode, the configuration of the robot hand mechanism operated in the diagonal movement mode, and the second opposing movement mode. The configuration of the robot hand mechanism is shown. When the robot hand mechanism shifts from the first facing movement mode to the diagonal movement mode, the first and second movable parts 305A and 305B are separated from each other by the drive motor 301 as shown in FIG. Moved in the direction. When the first movable portion 305A is moved in the x direction, the linear motion mechanical element 403 of the finger portion 101A and the linear motion mechanical element 403 of the finger portion 101C are moved in the x direction together with the first movable portion 305A. The rotating machine element 404 of 101A and the rotating machine element 404 of the finger part 101C are moved on circular trajectories around the passive rotating part 104 of the finger part 101A and the passive rotating part 104 of the finger part 101C, respectively. At this time, the movable link 402 of the finger unit 101A and the movable link 402 of the finger unit 101C are slid in the y direction, and the distance between the first movable unit 305A and the passive rotating unit 104 is shortened. The angle formed by the link 308 is increased.

  Similarly, when the second movable portion 305B is moved in the x direction and in the opposite direction to the first movable portion 305A, the linear motion mechanical element 403 of the finger portion 101B and the linear motion mechanical element 403 of the finger portion 101D are The rotary machine element 404 of the finger unit 101B and the rotary machine element 404 of the finger unit 101D are respectively moved in the x direction together with the second movable unit 305B, and the passive rotary unit 104 of the finger unit 101B and the passive rotary unit of the finger unit 101D, respectively. It is moved on a circular orbit centered at 104. At this time, the movable link 402 of the finger unit 101B and the movable link 402 of the finger unit 101D are slid in the y direction to shorten the distance between the second movable unit 305B and the passive rotating unit 104, and the movable link and the second link. The angle formed by is increased. In the transition from the first opposed movement mode to the diagonal movement mode, as shown in FIGS. 6A and 6B, each passive rotating unit 104 is rotated by 45 degrees. The rotation angle of the passive rotation unit 104 is controlled by adjusting the output of the drive motor 301.

  When the robot hand mechanism shifts from the diagonal movement mode to the second opposing movement mode, the first and second movable parts 305A and 305B are separated from each other by the drive motor 301, as shown in FIG. 6B. Moved in the direction. When the first movable portion 305A is moved in the x direction, the linear motion mechanical element 403 of the finger portion 101A and the linear motion mechanical element 403 of the finger portion 101C are moved in the x direction together with the first movable portion 305A. The rotating machine element 404 of 101A and the rotating machine element 404 of the finger part 101C are moved on circular trajectories around the passive rotating part 104 of the finger part 101A and the passive rotating part 104 of the finger part 101C, respectively. At this time, the movable link 402 of the finger unit 101A and the movable link 402 of the finger unit 101C are slid in the y direction to extend the distance between the first movable unit 305A and the passive rotating unit 104. The angle formed by the link 308 is increased.

  Similarly, when the second movable portion 305B is moved in the x direction, the linear motion mechanical element 403 of the finger portion 101B and the linear motion mechanical element 403 of the finger portion 101D are moved in the x direction together with the second movable portion 305B. The rotating machine element 404 of the finger unit 101B and the rotating machine element 404 of the finger unit 101D are moved on circular trajectories around the passive rotating unit 104 of the finger unit 101B and the passive rotating unit 104 of the finger unit 101D, respectively. At this time, the movable link 402 of the finger unit 101B and the movable link 402 of the finger unit 101D are slid in the y direction to extend the distance between the second movable unit 305B and the passive rotating unit 104, and the movable link and the second link. The angle formed by is increased. In the transition from the first opposed movement mode to the diagonal movement mode, as shown in FIGS. 6B and 6C, each passive rotation unit 104 is rotated by 45 degrees.

  The transition from the second opposing movement mode to the diagonal movement mode, and the transition from the diagonal movement mode to the first opposing movement mode, respectively, are the transition from the diagonal movement mode to the second opposing movement mode, and the first opposing movement, respectively. Since the operation is the reverse of the shift from the movement mode to the diagonal movement mode, the description thereof is omitted.

  In the robot hand mechanism according to the present embodiment, as shown in FIG. 7, even if the driving directions of the finger portions 101A, 101B, 101C, and 101D are changed, the positions of the finger portions 101A, 101B, 101C, and 101D with respect to the base portion Is not changed. In the following, this embodiment will be described in comparison with a comparative example using a robot hand mechanism in which the position of the finger is moved when changing the driving direction of the finger as a comparative example.

  Similar to the present embodiment, the robot hand mechanism according to the comparative example includes four finger portions 801A, 801B, 801C, and 801D, and is operated in the first and second opposing movement modes and the diagonal movement mode. In the comparative example, as shown in FIG. 8, the finger portions 801A, 801B, 801C, and 801D are moved on the circular orbits, thereby changing the driving directions of the finger portions 801A, 801B, 801C, and 801D. The operation mode is changed. More specifically, when the distance between the finger parts 801A and 801C in the diagonal movement mode is used as a reference, the distance between the finger parts 801A and 801C in the first opposed movement mode is larger than the reference.

  When gripping a relatively small target object, the robot hand mechanism of the comparative example cannot grip a relatively small target object because the interval between the finger portions is wide. On the other hand, the robot hand mechanism according to the present embodiment can hold such a relatively small target object even when operated in the first opposed movement mode because the distance between the finger portions is small. . Thus, the robot hand mechanism according to the present embodiment has a wider range of application to the target object than the comparative example.

  Furthermore, in the robot hand mechanism according to the comparative example, since the finger part is moved on the plane (xy plane), the driving direction of the finger part is represented by a function of two variables (x and y). On the other hand, in the robot hand mechanism according to the present embodiment, the driving direction of the finger portions 101A, 101B, 101C, and 101D is expressed as a function only of the rotation angle θ of the passive rotating portion 104. Therefore, the robot hand mechanism according to the present embodiment is easier to control than the comparative example.

  As described above, in the robot hand mechanism according to the present embodiment, the driving direction of the finger portion can be changed according to the shape of the target object, and a target article having an arbitrary shape can be stably gripped. it can. In addition, a change in the driving direction of the finger portion can be performed with a single drive motor. Further, when a ball screw mechanism is used as a mechanism for changing the driving direction of the finger part, a low output drive motor can be used because the ball screw mechanism has high transmission efficiency.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

101A, 101B, 101C, 101D ... finger part, 102 ... base part, 103 ... support part, 104 ... passive rotating part, 105 ... output shaft, 106 ... parallel link mechanism, 107 ... rotating part, 108 ... link, 301 ... drive motor , 302 ... coupling, 303 ... bearing part, 304 ... linear motion mechanism (ball screw shaft), 305 ... movable part (ball screw nut), 306 ... first link, 307 ... pin, 308 ... second link, 309 ... oblong hole , 310 ... Rotating shaft, 401 ... Connection mechanism, 402 ... Movable link, 403 ... Linear motion machine element, 404 ... Rotating machine element

Claims (2)

The base,
A linear motion mechanism that is disposed opposite the base and converts the rotational motion of the drive motor into linear motion;
A first movable part supported by the linear motion mechanism so as to be movable in a first direction;
A first connection mechanism coupled to one end side of the first movable part and converting a linear motion of the first movable part into a rotational movement around a second direction intersecting the first direction;
A first passive rotating part rotatably supported with respect to the base part and rotated by the first connection mechanism;
A first gripping part attached to the first passive rotating part;
A second connection mechanism coupled to the other end side of the first movable part and converting a linear motion of the first movable part into a rotational movement around the second direction;
A second passive rotating part rotatably supported with respect to the base part and rotated by the second connection mechanism;
A second gripping part attached to the second passive rotating part;
A second movable part supported by the linear motion mechanism so as to be movable in a direction opposite to the first movable part;
A third connection mechanism that is coupled to one end of the second movable part and converts a linear motion of the second movable part into a rotational motion around the second direction;
A third passive rotating part rotatably supported with respect to the base part and rotated by the third connection mechanism;
A third gripping part attached to the third passive rotating part;
A fourth connection mechanism that is coupled to the other end of the second movable part and converts a linear motion of the second movable part into a rotational motion around the second direction;
A fourth passive rotating part rotatably supported with respect to the base part and rotated by the fourth connection mechanism;
A fourth gripping part attached to the fourth passive rotating part;
Equipped with,
The first to fourth connection mechanisms include a first link provided with a pin at a tip portion, and a second link formed with an elongated hole that supports the pin so as to be slidable and rotatable. A robot hand characterized in that the two links are formed in a square shape . The linear motion mechanism moves the first and second movable parts, so that the first and third gripping parts are opposed to each other, and the second and fourth gripping parts are opposed to each other. The robot hand according to claim 1 , wherein the robot hand is switched to a second operation mode in which the first and second gripping portions face each other and the third and fourth gripping portions face each other.

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