Gripping device

Abstract

To provide a gripping device that can control while stabilizing grip force or finely adjust grip force without the need of a complicated control structure.SOLUTION: A gripping device 10 includes: a first arm 160 and a second arm 260 capable of rotating so as to approach / separate from each other; a first rotational power output part 110 and a second rotational power output part 210; and a first magnetic viscous fluid device 140 and a second magnetic viscous fluid device 240 for adjusting rotational power input from the first rotational power output part and the second rotational power output part so as to output to the first arm and the second arm. The first magnetic viscous fluid device 140 (second magnetic viscous fluid device 240) has an input side rotation part 7, an output side rotation part 8 rotating integrally with the first arm (second arm), a magnetic viscous fluid 14 interposed between the input side rotation part and the output side rotation part, and a magnetic field application part 9 for applying a magnetic field to the magnetic viscous fluid 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a gripping device for gripping an object to be gripped.

Background Art

[0002] As gripping devices, various ones have been proposed. For example, the gripping device disclosed in Patent Document 1 is configured to grip an object to be gripped by a pair of fingers driven by a DC motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a gripping device that drives a gripping part (finger) by an electric motor to grip an object to be gripped, such as the gripping device disclosed in Patent Document 1, a complex control configuration may be required in order to stabilize the gripping force or to finely adjust the gripping force.

[0005] The present invention was devised in view of the above circumstances, and an object thereof is to provide a gripping device that can control while stabilizing the gripping force or can finely adjust the gripping force without requiring a complex control configuration.

Means for Solving the Problems

[0006] The gripping device according to the first aspect of the present invention includes a plurality of arms rotatable so as to approach and separate from each other, a rotational power output unit that outputs rotational power, and a plurality of magnetorheological fluid devices that adjust the rotational power input from the rotational power output unit and output it to the arms. The magnetorheological fluid device has an input-side rotating part rotated by the rotational power input from the rotational power output unit, an output-side rotating part integrally rotated with the arm, a magnetorheological fluid interposed between the input-side rotating part and the output-side rotating part, and a magnetic field applying part that applies a magnetic field to the magnetorheological fluid.

[0007] According to the gripping device having such a configuration, by controlling the strength of the magnetic field applied by the magnetic field applying part to the magnetorheological fluid, the gripping force with which the arm grips the object to be gripped can be controlled. And since the relationship between the strength of the magnetic field applied by the magnetic field applying part to the magnetorheological fluid and the rotational power transmitted from the input-side rotating part to the output-side rotating part by the magnetorheological fluid is generally uniquely determined, according to the gripping device according to the first aspect of the present invention, it is possible to control while stabilizing the gripping force without requiring a complicated control configuration, or to finely adjust the gripping force.

[0008] The gripping device according to the second aspect of the present invention is the gripping device according to the first aspect, wherein the plurality of arms are composed of a first arm and a second arm, the plurality of magnetorheological fluid devices are composed of a first magnetorheological fluid device that outputs the rotational power adjusted to the first arm and a second magnetorheological fluid device that outputs the rotational power adjusted to the second arm, and further includes a movement restricting member that restricts the movement of the second arm when approaching the first arm at a predetermined position.

[0009] The gripping device according to the third aspect of the present invention is the gripping device according to the second aspect, wherein the magnetic field applying unit includes a coil that generates a magnetic field when an electric current is input, and the coil includes a first coil disposed in the first magnetorheological fluid device and a second coil disposed in the second magnetorheological fluid device. This gripping device further includes a current control unit that controls the electric currents input to the first coil and the second coil. The current control unit inputs an electric current to the second coil before inputting an electric current to the first coil.

[0010] The gripping device according to the fourth aspect of the present invention is the gripping device according to the third aspect, wherein the current control unit controls the values of the electric currents input to the respective coils such that the value of the electric current input to the second coil is greater than the value of the electric current input to the first coil.

[0011] The gripping device according to the fifth aspect of the present invention is the gripping device according to the fourth aspect, wherein the current control unit controls the magnitude of the gripping force when gripping an object to be gripped by the first arm and the second arm by controlling the value of the electric current input to the first coil.

[0012] The gripping device according to the sixth aspect of the present invention is the gripping device according to the first to fifth aspects, further including a support member that supports the magnetorheological fluid device, and one axial portion of the output side rotating portion of the magnetorheological fluid device is rotatably supported by the support member via a bearing, and the other axial portion of the output side rotating portion is integrally and rotatably fixed to the arm.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a gripping device that can control while stabilizing the gripping force or finely adjust the gripping force without requiring a complicated control configuration.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0015] Hereinafter, the gripping device according to an embodiment of the present invention will be described with reference to the drawings. In this specification, the directions are defined as follows. The left, right, upper, and lower directions in FIG. 1 are defined as the "left", "right", "upper", and "lower" directions of the gripping device, respectively. Also, the front side of the paper in the direction orthogonal to the paper surface of FIG. 1 is defined as the "front" of the gripping device, and the back side of the paper in the direction orthogonal to the paper surface of FIG. 1 is defined as the "rear" of the gripping device.

[0016] The gripping device 10 according to this embodiment grips a gripping object W (see FIG. 6). The gripping device 10 is used, for example, by being attached to the tip of an arm (not shown) of an industrial robot. As shown in FIGS. 1 to 5, the gripping device 10 includes a support member 100, two rotational power output units 110 and 210, two magnetorheological fluid devices 140 and 240, two arms 160 and 260, two tension members 170 and 270, a movement restricting member 300, and a current control unit 400.

[0017] Hereinafter, among the two rotational power output units 110 and 210, the two magnetorheological fluid devices 140 and 240, the two arms 160 and 260, and the two tension members 170 and 270, those arranged on the right side are referred to as a first rotational power output unit 110, a first magnetorheological fluid device 140, a first arm 160, and a first tension member 170, respectively, and those arranged on the left side are referred to as a second rotational power output unit 210, a second magnetorheological fluid device 240, a second arm 260, and a second tension member 270, respectively. Further, in this embodiment, since an electric motor is exemplified as the rotational power output units 110 and 210, hereinafter, the first rotational power output unit 110 is referred to as a first motor unit 110, and the second rotational power output unit 210 is referred to as a second motor unit 210.

[0018] The support member 100 includes a rotational power output unit support member 101 (hereinafter referred to as a “motor support member 101”), a magnetorheological fluid device support member 102 (hereinafter referred to as an “MRF device support member 102”), a connecting member 103, and a connecting member 104.

[0019] The motor support member 101 supports the first motor unit 110 and the second motor unit 210. The motor support member 101 includes a flat plate-shaped motor support member main body 101a extending in the front-rear direction and the left-right direction, a first support body 101b1 that supports the first motor unit 110 disposed below the motor support member main body 101a and on the right side of FIG. 1 from below, and a second support body 101b2 that supports the second motor unit 210 disposed below the motor support member main body 101a and on the left side of FIG. 1 from below.

[0020] The first support body 101b1 has a concave groove that extends in the front-rear direction and opens upward, and houses and supports the first motor unit 110 in the concave groove. The upper end of the first support body 101b1 is fixed to the lower right surface of the motor support member main body 101a.

[0021] Similarly, the second support body 101b2 has a concave groove that extends in the front-rear direction and opens upward, and houses and supports the second motor unit 210 in the concave groove. The upper end of the second support body 101b2 is fixed to the lower left surface of the motor support member main body 101a.

[0022] The MRF device support member 102 supports the first magnetorheological fluid device 140 and the second magnetorheological fluid device 240. A flat plate-shaped member that extends in the left-right direction and the up-down direction is used for the MRF device support member 102. As shown in FIG. 3, two circular holes 102h1, 102h2 are formed in the MRF device support member 102. A bearing 150 for the first magnetorheological fluid device is fitted into the left circular hole 102h1, and the first magnetorheological fluid device 140 is fitted inside the bearing 150 for the first magnetorheological fluid device. A bearing 250 for the second magnetorheological fluid device is fitted into the right circular hole 102h2, and the second magnetorheological fluid device 240 is fitted inside the bearing 250 for the second magnetorheological fluid device.

[0023] The connecting member 103 connects the motor support member 101 and the MRF device support member 102 in the front-rear direction. As shown in FIG. 2, the connecting member 103 is a member having an inverted L shape in side view, and connects the upper rear surface of the motor support member 101 and the upper front portion of the MRF device support member 102. Thereby, the first motor unit 110 and the first magnetorheological fluid device 140 are supported side by side in the front-rear direction (axial direction), and the second motor unit 210 and the second magnetorheological fluid device 240 are supported side by side in the front-rear direction (axial direction).

[0024] As shown in FIGS. 2 and 5, the connecting member 104 extends upward from the rear side at the intermediate position in the left-right direction of the connecting member 103.

[0025] The connecting member 104 is used, for example, as a connection part to another movable device. Examples of other movable devices include the arm of an industrial robot.

[0026] Next, the first and second motor units 110 and 210, the first and second magnetorheological fluid devices 140 and 240, the first and second arms 160 and 260, and the first and second tension members 170 and 270 attached to the support member 100 will be described in order.

[0027] The first and second motor units 110 and 210 output rotational power to the first and second magnetorheological fluid devices 140 and 240, respectively. The first and second motor units 110 and 210 are supported by the motor support member 101 with their output shafts facing rearward. The first and second motor units 110 and 210 are an example of the first and second rotational power output units 110 and 210 capable of outputting rotational power, and in this embodiment, they are electric motors. The first and second motor units 110 and 210 are electrically connected to a power supply device (not shown). The power supply device may also serve as the current control unit 400, or it may be provided separately from the current control unit 400. In this embodiment, the first motor unit 110 always outputs rotational power in one direction (clockwise in FIG. 1) when the gripping device 10 is in use. The second motor unit 210 always outputs rotational power in the other direction (counterclockwise in FIG. 1) when the gripping device 10 is in use. The first and second motor units 110 and 210 include the first and second motor unit bodies 112 and 212 fixed to the motor support member 101, and the first and second motor unit output shafts 114 and 214 extending rearward from the first and second motor unit bodies 112 and 212.

[0028] The first and second magnetorheological fluid devices 140 and 240 respectively adjust the rotational power input from the first and second motor units 110 and 210 and output it to the first and second arms 160 and 260. The first and second magnetorheological fluid devices 140 and 240 change the viscosity of the magnetorheological fluid 14 by changing the strength of the magnetic field applied to the magnetorheological fluid 14 enclosed therein, and adjust and output the input rotational power. An example of the first and second magnetorheological fluid devices 140 and 240 is shown in FIG. 10. Note that the first and second magnetorheological fluid devices 140 and 240 are not limited to the embodiment shown in FIG. 10.

[0029] The first and second magnetorheological fluid devices 140 and 240 shown in FIG. 10 are composed of an input-side rotating part 7, an output-side rotating part 8, a magnetic field applying part 9, a magnetorheological fluid 14, etc.

[0030] The input-side rotating part 7 is rotated by the rotational power input from the first and second motor units 110 and 210. The input-side rotating part 7 includes a shaft 6 and a disk 12 with the base end of the shaft 6 fixed at the center. The shaft 6 is rotationally and integrally connected to the first and second motor unit output shafts 114 and 214 of the first and second motor units 110 and 210. The shaft 6 is rotatably supported by a shaft hole formed in the output-side rotating part 8. In this embodiment, the input-side rotating part 7 rotates constantly by the rotational power input from the first and second motor units 110 and 210 that output a constant rotational power at all times.

[0031] The output-side rotating part 8 functions as a casing of the first and second magnetorheological fluid devices 140 and 240 and rotatably houses the disk 12. Inside the output-side rotating part 8, first and second coils 91 and 92 that constitute the magnetic field applying part 9 wound concentrically with the shaft 6 are provided on the radially outer side of the disk 12. Note that the output-side rotating part 8 is made of a magnetic material and also functions as a yoke that constitutes the magnetic field applying part 9 together with the first and second coils 91 and 92.

[0032] As shown in FIG. 4, the rear side (one axial part) of the outer peripheral surface of the output-side rotating part 8 of the first magnetorheological fluid device 140 is fitted to the inner diameter side of the bearing 150 for the first magnetorheological fluid device. Similarly, although not shown, the rear side (one axial part) of the outer peripheral surface of the output-side rotating part 8 of the second magnetorheological fluid device 240 is fitted to the inner diameter side of the bearing 250 for the second magnetorheological fluid device. Thereby, the rear side (one axial part) of the outer peripheral surface of the output-side rotating part 8 of the first and second magnetorheological fluid devices 140 and 240 is rotatably supported by the MRF device support member 102 via the bearings 150 and 250 for the first and second magnetorheological fluid devices.

[0033] The front side (the other axial part) of the outer peripheral surface of the output-side rotating part 8 is integrally and rotatably attached to the first and second arms 160 and 260, which will be described in detail later.

[0034] As shown in FIG. 10, the magnetic field applying part 9 applies a magnetic field to the magnetorheological fluid 14. The magnetic field applying parts 9 of the first and second magnetorheological fluid devices 140 and 240 are each composed of a bobbin, first and second coils 91 and 92, and a yoke, and a current is supplied to the first and second coils 91 and 92 from the current control part 400 via the electric wire 13 so that the current value can be controlled. When a current is applied to the first and second coils 91 and 92 of the magnetic field applying part 9, a magnetic path is formed on the output-side rotating part 8, the disk 12, and the magnetorheological fluid 14 intervening in the gap therebetween along the direction indicated by the arrow P in FIG. 10.

[0035] The magnetorheological fluid 14 is enclosed in an enclosed space 11 within the output-side rotating portion 8. In FIG. 10, the region filled in gray represents the enclosed space 11. That is, the magnetorheological fluid 14 is interposed between the input-side rotating portion 7 and the output-side rotating portion 8. Specifically, the magnetorheological fluid 14 is interposed in the gap between the disk 12 and the output-side rotating portion 8, and performs torque transmission according to the strength of the applied magnetic field between the disk 12 and the output-side rotating portion 8. Thereby, the first and second magnetorheological fluid devices 140 and 240 increase the rotational power output according to the strength of the magnetic field. In the present embodiment, since the disk 12 (input-side rotating portion 7) receives a constant rotational power from the first and second motor portions 110 and 210 and rotates constantly, the magnitude of the rotational power transmitted from the input-side rotating portion 7 to the output-side rotating portion 8 and output by the output-side rotating portion 8 is determined according to the magnitude of the magnetic field applied to the magnetorheological fluid 14 interposed therebetween. Even when the magnetic field applied to the magnetorheological fluid 14 is 0, since the magnetorheological fluid 14 has a certain viscosity and there is a sliding resistance between the shaft 6 and the seal portion, even when the magnetic field applied to the magnetorheological fluid 14 is 0, a constant rotational power is transmitted from the input-side rotating portion 7 to the output-side rotating portion 8. Hereinafter, the rotational power transmitted from the input-side rotating portion 7 to the output-side rotating portion 8 when the applied magnetic field is 0 is referred to as "base torque".

[0036] The magnetorheological fluid 14 is a liquid in which magnetic particles are dispersed in a dispersion medium. As the magnetic particles, for example, nano-sized metal particles (metal nanoparticles) can be used. The magnetic particles are made of a magnetizable metal material, and there is no particular limitation on the metal material, but a soft magnetic material is preferred. Examples of the soft magnetic material include alloys such as iron, cobalt, nickel, and permalloy. The dispersion medium is not particularly limited, and a well-known dispersion medium generally used for magnetorheological fluids can be used.

[0037] The first and second motor portion output shafts 114 and 214 and the shaft 6 are rotatably and integrally connected via the first and second shaft joints 120 and 220. The first and second shaft joints 120 and 220 are rotatably supported by the first and second shaft joint bearings 130 and 230 fixed to the motor support member 101.

[0038] The first arm 160 and the second arm 260 rotate so as to approach and separate from each other. The first arm 160 rotates with respect to the MRF device support member 102 and abuts against the right side of the object W to be gripped (see FIG. 6). Similarly, the second arm 260 rotates with respect to the MRF device support member 102 and abuts against the left side of the object W to be gripped. The first arm 160 and the second arm 260 that abut against the right side and the left side of the object W to be gripped respectively grip the object W to be gripped as shown in FIG. 9.

[0039] As shown in FIG. 5, the first and second arms 160 and 260 are fixed to the respective output-side rotating portions 8 so as to rotate integrally with the output-side rotating portions 8 of the first and second magnetorheological fluid devices 140 and 240. Thereby, the first and second arms 160 and 260 receive the rotational power output from the output-side rotating portions 8 of the first and second magnetorheological fluid devices 140 and 240 and exert a gripping force on the object W to be gripped. The first and second arms 160 and 260 include first and second arm supported portions 162 and 262, first and second arm main bodies 164 and 264, and first and second arm abutting portions 166 and 266.

[0040] As shown in FIG. 4, the first arm supported portion 162 is integrally rotatably fixed to and supported by the front side of the outer peripheral surface of the output-side rotating portion 8 of the first magnetorheological fluid device 140. Similarly, although not shown, the second arm supported portion 262 is integrally rotatably fixed to and supported by the front side of the outer peripheral surface of the output-side rotating portion 8 of the second magnetorheological fluid device 240. In the examples shown in FIGS. 4 and 5, the first and second arm supported portions 162 and 262 are fixed to the output-side rotating portion 8 by sandwiching the output-side rotating portion 8.

[0041] As shown in FIGS. 1 and 5, the first and second arm supported portions 162 and 262 are formed in a C shape, and both ends thereof bulge forward (the front side of the paper surface in FIG. 1) to form a pair of first and second arm clamped portions 162a and 262a. Bolt insertion holes are formed in the pair of first and second arm clamped portions 162a and 262a. Further, bolts are inserted into the bolt insertion holes, and nuts are screwed onto the bolts. By tightening the bolts and nuts, the first and second arm supported portions 162 and 262 are integrally and rotatably fixed to the output side rotating portion 8 of the first and second magnetorheological fluid devices 140 and 240. The bolts and nuts are referred to as first and second arm clamping members 162b and 262b.

[0042] The first and second arm bodies 164 and 264 extend radially outward in an arm shape from the C-shaped first and second arm supported portions 162 and 262. The first and second arm bodies 164 and 264 rotate as the first and second arm supported portions 162 and 262 rotate. As a result, the tip sides of the first and second arm bodies 164 and 264 contact the object to be gripped W via the first and second arm contact portions 166 and 266 as shown in FIG. 8, and the object to be gripped W can be gripped between them.

[0043] The first arm body 164 and the second arm body 264 are biased by a first tension member 170 and a second tension member 270, respectively, so as to move away from each other. For example, tension springs are used for the first tension member 170 and the second tension member 270. One end of each of the first and second tension members 170 and 270 is attached to the proximal end side of the first and second arm bodies 164 and 264, and the other end is attached to the MRF device support member 102. The magnitude of the biasing force of the first and second tension members 170 and 270 is set to exert a torque greater than the base torque input to the first and second arms 160 and 260 on the first and second arms 160 and 260.

[0044] The first and second arm contact portions 166 and 266 contact the object W to be gripped and exert a gripping force. In the present embodiment, the first and second arm contact portions 166 and 266 are metal plate-like bodies. The first and second arm contact portions 166 and 266 are attached to the first and second arm main bodies 164 and 264 such that their main surfaces face the object W to be gripped. The first and second arm contact portions 166 and 266 can be appropriately replaced according to the hardness, shape, etc. of the object W to be gripped.

[0045] As shown in FIG. 1, the movement restricting member 300 restricts the rotation (movement) of the second arm 260 at a predetermined position when the second arm 260 approaches the first arm 160. As shown in FIG. 1, the movement restricting member 300 is provided below the MRF device support member 102 and at a position slightly shifted to the left from the intermediate position in the left-right direction of the MRF device support member 102. When the second arm main body 264 moves rightward (toward the first arm main body 164), as shown in FIG. 7, the movement restricting member 300 contacts the second arm contact portion 266 and restricts the second arm main body 264 from moving further rightward. The movement restricting member 300 is configured using a hexagonal socket bolt 302 and a nut 304.

[0046] The hexagonal socket bolt 302 is inserted into the long hole 102i formed in the MRF device support member 102 with its shaft portion oriented in the front-rear direction, and is attached to the MRF device support member 102 using the nut 304. The head of the hexagonal socket bolt 302 protrudes forward from the MRF device support member 102, and when the second arm contact portion 266 moves to a predetermined position, it contacts the second arm contact portion 266 and restricts its movement. The hexagonal socket bolt 302 can be fixed at any position within the long hole 102i.

[0047] The position where the movement restricting member 300 is fixed is determined according to the size of the object W to be gripped. If the object W to be gripped is small, it is desirable to fix the movement restricting member 300 at a position closer to the right of the long hole 102i (a position relatively close to the first arm 160). Conversely, if the object W to be gripped is large, it is desirable to fix the movement restricting member 300 at a position closer to the left of the long hole 102i (a position away from the first arm 160). By setting the position of the movement restricting member 300 in this way, the object W can be gripped at the center position in the left - right direction of the gripping device 10 without being affected by the size of the object W to be gripped.

[0048] The current control unit 400 controls the currents input to the first coil 91 and the second coil 92, for example, according to a command input from the outside. Examples of the command input from the outside include a command to grip the object W to be gripped and a command to release the gripped object W. The current control unit 400 inputs currents to the first coil 91 and the second coil 92 respectively, and controls the value of each current and the time for which the current is input. Thereby, the current control unit 400 can individually control the rotational power transmitted to the first arm 160 and the rotational power transmitted to the second arm 260.

[0049] For example, in order to rotate the second arm 260 earlier than the first arm 160 while making the rotational power transmitted to the second arm 260 larger than the rotational power transmitted to the first arm 160, the current control unit 400 controls the value of the current input to each coil so that the value of the current input to the second coil 92 is larger than the value of the current input to the first coil 91, and inputs a current to the second coil 92 before inputting a current to the first coil 91.

[0050] Furthermore, for example, in order to finely adjust the gripping force for gripping the object to be gripped W, the current control unit 400 controls the magnitude of the gripping force when gripping the object to be gripped W with the second arm 260 and the first arm 160 by controlling the value of the current input to the first coil 91. That is, the current control unit 400 performs control to finely adjust the value of the current input to the first coil 91 in a state where the value of the current input to the second coil 92 is larger than the value of the current input to the first coil 91, so as to finely adjust the magnitude of the gripping force when gripping the object to be gripped W with the second arm 260 and the first arm 160.

[0051] The object to be gripped W gripped by the gripping device 10 is not particularly limited, but in the present embodiment, it has a cubic shape and has a certain rigidity, and will be described below as such.

[0052] Next, the respective movements of the first arm 160 and the second arm 260 when the gripping device 10 grips the object to be gripped W will be described with reference to FIGS. 6 to 9.

[0053] Here, as shown in FIG. 6, the gripping device 10 is disposed directly above the object to be gripped W, and the case where the object to be gripped W is located slightly to the right of the intermediate position in the left-right direction of the gripping device 10 will be described as an example.

[0054] When a command for gripping the object to be gripped W is input to the current control unit 400, the current control unit 400 first inputs a current to the second coil 92. As a result, a counterclockwise rotational power is input from the second magnetorheological fluid device 240 to the second arm 260, and the second arm 260 starts rotating (moving) earlier than the first arm 160. The second arm contact portion 266 of the second arm 260 that has started rotating contacts the movement restricting member 300 as shown in FIG. 7, and its further movement (rotation) is restricted.

[0055] The current control unit 400 inputs current to the second coil 92. After a predetermined time has elapsed, the current control unit 400 inputs current to the first coil 91. As a result, clockwise rotational power is input from the first magnetorheological fluid device 140 to the first arm 160, and the first arm 160 starts to rotate (move) later than the second arm 260. The first arm contact portion 166 of the first arm 160 that has started to rotate soon contacts the object W to be gripped as shown in FIG. 8, and subsequently, the first arm contact portion 166 rotates to move the object W to be gripped toward the second arm 260.

[0056] The object W to be gripped that moves together with the first arm 160 then contacts the second arm contact portion 266 of the second arm 260 whose movement is restricted, and as shown in FIG. 9, it is in a state of being gripped by the first arm 160 and the second arm 260. By the respective movements of the first arm 160 and the second arm 260 in the above series of operations, the gripping device 10 grips the object W to be gripped at a predetermined gripping position.

[0057] After that, for example, the gripping device 10 connected to the arm of an industrial robot moves the gripped object W to a predetermined position, and then a command for releasing the object W to be gripped is input to the current control unit 400, and the object W to be gripped is released from the first arm 160 and the second arm 260.

[0058] When a command for releasing the object W to be gripped is input to the current control unit 400, the current control unit 400 stops the current input to the first coil 91 and the second coil 92, respectively. As a result, the first arm 160 and the second arm 260 are separated from each other by the biasing forces of the first tension member 170 and the second tension member 270, and the object W to be gripped is released from the first arm 160 and the second arm 260.

[0059] (Function and Effect) According to the gripping device 10 according to the present embodiment described above, by controlling the strength of the current applied to the first and second coils 91 and 92 of the first and second magnetorheological fluid devices 140 and 240, the gripping force with which the first and second arms 160 and 260 grip the object to be gripped W can be controlled. And since the relationship between the strength of the current applied to the first and second coils 91 and 92 of the first and second magnetorheological fluid devices 140 and 240 and the rotational power transmitted from the input side rotating part 7 to the output side rotating part 8 via the magnetorheological fluid 14 is generally uniquely determined, according to the gripping device 10, it is possible to control while stabilizing the gripping force without requiring a complicated control configuration, and it is possible to finely adjust the gripping force.

[0060] Furthermore, according to the gripping device 10, the position at which the second arm 260 stops rotating can be determined by the movement restricting member 300, and thereby, the gripping position at which the second arm 260 grips the object to be gripped W together with the first arm 160 can be defined. As a result, it is possible to suppress the gripping position from becoming a different position every time gripping is performed.

[0061] Furthermore, according to the gripping device 10, the second arm 260 starts moving (rotating) earlier than the first arm 160, and after the movement of the second arm 260 is restricted by the movement restricting member 300, the object to be gripped W can be gripped by the first arm 160 and the second arm 260. Thereby, according to the gripping device 10, the gripping position can be defined more reliably, and it is possible to suppress the gripping position from becoming a different position every time gripping is performed.

[0062] Furthermore, according to the gripping device 10, since the current control unit 400 controls the value of the current input to each coil so that the value of the current input to the second coil 92 becomes larger than the value of the current input to the first coil 91, the rotational power output to the second arm 260 becomes larger than the rotational power output to the first arm 160. Thereby, when the object to be gripped W is gripped by the second arm 260 and the first arm 160 whose movement is restricted by the movement restricting member 300, it is possible to suppress the second arm 260 from being pushed by the object to be gripped W against the first arm 160 and the gripping position from changing.

[0063] (Modified Example) Next, a modified example of the gripping device 10 according to the above embodiment will be described. The modified example will be described without being illustrated.

[0064] In the above embodiment, the gripping device 10 has been described as including two arms (the first arm 160 and the second arm 260), but the number of arms included in the gripping device 10 is not limited to two. The gripping device 10 may include three or more arms that are rotatable so as to approach and separate from each other.

[0065] Further, when the gripping device 10 includes three or more arms, the gripping device 10 may include the same number of magnetorheological fluid devices that adjust and output rotational power to each arm.

[0066] Also, the gripping device 10 may be configured to be a left - right reversed version of the gripping device 10 in the above embodiment. That is, in the above embodiment, the second motor unit 210, the second magnetorheological fluid device 240, the second arm 260, and the movement restricting member 300 have been described as being arranged on the left side of the gripping device 10, but they may be arranged on the right side of the gripping device 10, and the first motor unit 110, the first magnetorheological fluid device 140, and the first arm 160 may be arranged on the left side of the gripping device 10.

[0067] In addition, in the above-described embodiment, the first motor unit 110 and the second motor unit 210 have been described as outputting a constant rotational power at all times. However, when the first arm 160 and the second arm 260 rotate (move) respectively, they may output rotational power respectively. For example, the current control unit 400 is made to turn on and off the current supplied from the power supply device to the first motor unit 110 and the second motor unit 210, and the current control unit 400 is configured to operate as follows. That is, before a command for gripping the object to be gripped W is input, the current control unit 400 prevents the current from being supplied from the power supply device to the first motor unit 110 and the second motor unit 210. Thereafter, when a command for gripping the object to be gripped W is input, the current control unit 400 supplies the current from the power supply device to the first motor unit 110 and the second motor unit 210.

[0068] Further, in the above-described embodiment, the two motor units 110 and 210 provided in the gripping device 10 may be changed to one motor unit, and the rotational power output from one motor unit may be split into two through a well-known rotational power splitting mechanism, and the rotational power may be transmitted to the first magnetorheological fluid device 140 and the second magnetorheological fluid device 240.

[0069] In addition, in the above-described embodiment, the first rotational power output unit 110 and the second rotational power output unit 210 are configured using electric motors. However, the first rotational power output unit 110 and the second rotational power output unit 210 may be any device that outputs rotational power, for example, a hydraulic motor or a spring motor.

Industrial Applicability

[0070] The present invention can be applied to, for example, a gripping device for gripping an object to be gripped.

Explanation of Reference Numerals

[0071] 10 Gripping device 100 Support member 110 First rotational power output unit (first motor unit) 140 First Magnetorheological Fluid Device 7 Input Side Rotating Part 8 Output Side Rotating Part 9 Magnetic Field Application Part 91 First Coil 92 Second Coil 14 Magnetorheological Fluid 160 First Arm 210 Second Rotational Power Output Part (Second Motor Part) 240 Second Magnetorheological Fluid Device 260 Second Arm 300 Movement Restriction Member 400 Current Control Unit

Claims

Claim 1: A plurality of arms rotatable so as to approach and separate from each other, A rotational power output unit that outputs rotational power, A plurality of magnetorheological fluid devices that adjust the rotational power input from the rotational power output unit and output it to the arms, Comprising: The magnetorheological fluid device An input-side rotating part rotated by the rotational power input from the rotational power output unit, An output-side rotating part that rotates integrally with the arm, A magnetorheological fluid interposed between the input-side rotating part and the output-side rotating part, A magnetic field application part that applies a magnetic field to the magnetorheological fluid, Having: The plurality of arms are composed of a first arm and a second arm, The plurality of magnetorheological fluid devices are composed of a first magnetorheological fluid device that outputs the rotational power adjusted to the first arm and a second magnetorheological fluid device that outputs the rotational power adjusted to the second arm, Further comprising a movement restricting member that restricts the movement when the second arm approaches the first arm at a predetermined position, The magnetic field application part includes a coil that generates a magnetic field when an electric current is input, The coil is composed of a first coil disposed in the first magnetorheological fluid device and a second coil disposed in the second magnetorheological fluid device, Further comprising a current control part that controls the electric current input to the first coil and the second coil, The current control part inputs an electric current to the second coil before inputting an electric current to the first coil, A gripping device characterized by the above. Claim 2 The gripping device according to claim 1, The current control part controls the value of the electric current input to each coil so that the value of the electric current input to the second coil is larger than the value of the electric current input to the first coil, A gripping device characterized by the above. Claim 3 The gripping device according to claim 2, The current control part controls the magnitude of the gripping force when gripping an object to be gripped by the first arm and the second arm by controlling the value of the electric current input to the first coil, A gripping device characterized by the above. Claim 4: A plurality of arms rotatable so as to approach and separate from each other, A rotational power output unit that outputs rotational power, A plurality of magnetorheological fluid devices that adjust the rotational power input from the rotational power output unit and output it to the arms, Comprising: The magnetorheological fluid device An input-side rotating part rotated by the rotational power input from the rotational power output unit, An output-side rotating part that rotates integrally with the arm, a magnetorheological fluid interposed between the input-side rotating part and the output-side rotating part; a magnetic field applying part that applies a magnetic field to the magnetorheological fluid; and further includes a support member that supports the magnetorheological fluid device; one axial part of the output-side rotating part of the magnetorheological fluid device is rotatably supported by the support member via a bearing; the other axial part of the output-side rotating part is integrally and rotatably fixed to the arm; A gripping device characterized by the above.

5. The gripping device according to claim 4, wherein the plurality of arms are composed of a first arm and a second arm; the plurality of magnetorheological fluid devices are composed of a first magnetorheological fluid device that outputs adjusted rotational power to the first arm and a second magnetorheological fluid device that outputs adjusted rotational power to the second arm; further includes a movement restricting member that restricts the movement when the second arm approaches the first arm at a predetermined position; A gripping device characterized by the above.

6. The gripping device according to claim 5, wherein the magnetic field applying part includes a coil that generates a magnetic field when a current is input; the coil is composed of a first coil arranged in the first magnetorheological fluid device and a second coil arranged in the second magnetorheological fluid device; further includes a current control part that controls the current input to the first coil and the second coil; the current control part inputs a current to the second coil before inputting a current to the first coil; A gripping device characterized by the above.

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