Robot hand

Abstract

A robot hand (10) includes two or more finger parts (20, 30) and has a forward / backward moving mechanism (60) which makes at least one finger part (30) move slidably, independently of the other one or more finger parts (20), in the forward / backward directions of the robot hand (10).

Description

Robot Hand

[0001] The present disclosure relates to a robotic hand.

[0002] A gripper that grips an object has been proposed (see Patent Document 1). This gripper is capable of holding and transporting an object.

[0003] Patent No. 6678648

[0004] There is a demand for robotic hands that can hold a variety of objects.

[0005] Therefore, an object of the present disclosure is to provide a robot hand that can hold a variety of objects.

[0006] In order to achieve the above object, a robot hand according to one embodiment of the present disclosure is a robot hand having two or more fingers, and a mechanism for sliding one or more of the two or more fingers in a forward and backward direction independently of the other one or more fingers, wherein the forward and backward direction is one of the following: (1) a direction connecting a tip of one of the one or more fingers and the center of gravity of a base member of the robot hand, which is a point directly connected to a mechanical device made up of multiple parts; (2) a direction along a normal vector of a connection surface directly connecting the mechanical device and the robot hand; (3) a direction connecting the center of gravity of a part directly connected to the robot hand, among the multiple parts making up the mechanical device, and the center of gravity of the robot hand; or (4) a direction along which the diameter of an ellipsoid is longest when the outer shape of the robot hand is approximated by the ellipsoid with the one or more fingers extended.

[0007] The present disclosure provides a robotic hand that can hold a variety of objects.

[0008] Fig. 1 is an external perspective view of a robot hand according to an embodiment. Fig. 2 is an external perspective view of the robot hand shown in Fig. 1 with one finger moved backward. The other finger is hidden within a cover. Fig. 3 is an external perspective view of the robot hand shown in Fig. 1 with the other finger moved backward and one finger sucking the top surface of an object to hold the object. Fig. 4 is an external perspective view of the robot hand shown in Fig. 1 with one finger sucking the top surface of an object and the other finger moving backward while changing the angle of the finger tip to suck the side of the object to hold the object.

[0009] (Embodiments) Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. The numerical values, shapes, materials, components, component arrangement and connection configurations, steps, step order, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, each figure is not necessarily an exact illustration. In each figure, substantially identical configurations are assigned the same reference numerals, and duplicated explanations may be omitted or simplified.

[0010] (External Perspective View) Fig. 1 is an external perspective view of a robot hand 10 according to an embodiment. The robot hand 10 includes finger portions 20 and 30, a base member 12, and a control unit 15. Fig. 1 shows a state in which the two finger portions 20, 30 of the robot hand 10 are loosely closed. Note that this figure also shows a mechanical device 50 to which the robot hand 10 is attached.

[0011] The robot hand 10 is a robotic hand capable of grasping and holding an object. For example, the robotic hand 10 is attached to a mechanical device 50. As needed, each of the two fingers 20, 30 can be rotated about a first rotation axis A1, a second rotation axis A2, a third rotation axis A3, and a fourth rotation axis A4, moving toward or away from the other of the two fingers 20, 30. This allows the relative positions of the fingers to be changed, allowing the object to be sandwiched between the fingers 20 and 30 and held. Mechanisms (finger drive units) for driving the first rotation axis A1, the second rotation axis A2, the third rotation axis A3, and the fourth rotation axis A4 are installed inside the fingers around the respective axes (not shown). The shapes of the joints around the rotation axes of the fingers in FIG. 1 are merely schematic representations and do not represent the exact physical structure.

[0012] The definition of a "finger" may be a rod-shaped portion having one or more rotating joints. The number of rotating joints may also be two or more. The definition of a "finger" may also be "a rod-shaped portion having a mechanism for bending the finger by deformation of the entire finger or an entire region of the finger." For example, the finger may be made of a flexible material that is easily deformed, and have a mechanism for bending the finger by deformation of the entire finger.

[0013] The definition of a finger may also be a rod-shaped portion having some kind of drive mechanism. In this case, the drive mechanism may include not only a rotating joint or the above-mentioned "mechanism for bending the entire finger or a partial region," but also a drive mechanism for expanding and contracting the finger. Furthermore, a drive mechanism for some kind of deformation mechanism may also be included in the above-mentioned "some kind of drive mechanism."

[0014] Note that the robot hand 10 according to the present disclosure does not necessarily have to have joints around the rotation axes of the fingers shown in Fig. 1. Similarly, the robot hand 10 according to the present disclosure does not necessarily have to have the control unit 15 shown in Fig. 1.

[0015] The robot hand 10 is also capable of adsorbing and holding an object. Similarly, the robot hand 10 is attached to a mechanical device 50, for example.

[0016] The robot hand 10 also includes a forward / backward direction movement mechanism 60 that moves the fingers 30 backward (negative y direction) or forward (positive y direction) (see FIG. 2 ). Note that the y-axis indicates the forward / backward direction defined in this specification, the x-axis indicates a direction perpendicular to the y-axis, and the z-axis indicates a direction perpendicular to the x-axis and y-axis.

[0017] The control unit 15 is a controller that controls the robot hand 10, and is comprised of a memory that stores programs and object information, a processor that executes the programs, a camera as object detection means that detects the status of the object to be held, etc., and is housed in the mechanical device 50, etc. Note that in Figure 1, the control unit 15 is illustrated functionally.

[0018] 2 is a perspective view of the appearance of the robot hand 10 according to the embodiment, in which one finger (here, the finger portion 30) is moved backward (in the negative y direction) by the forward / backward direction movement mechanism 60 under the control of the control unit 15. Note that the mechanical device 50 and the control unit 15 shown in FIG. 1 are omitted from the illustration in FIG. 2 . This also applies to the subsequent figures.

[0019] (Forward / backward movement) Here, forward / backward movement may mean that the relative positional relationship of the fingers or finger tips with respect to the base member 12 of the robot hand or the part 51 to which the robot hand is attached can be changed in the forward / backward direction, or it may mean that the finger parts can be slid in and out in the forward / backward direction.

[0020] (Description of Front-rear Direction) The front-rear direction may be any of the following directions.

[0021] (1) The direction connecting the tip of one of the fingers and the center of gravity of the base member 12 of the robot hand 10, which is the point directly connected to the mechanical device 50 consisting of multiple parts; (2) The direction along the normal vector of the connection surface 11 directly connecting the mechanical device 50 and the robot hand 10; (3) The direction connecting the center of gravity of the part 51 that is directly connected to the robot hand 10 among the parts that make up the mechanical device 50 and the center of gravity of the robot hand 10; (4) The direction with the longest diameter of the ellipsoid when the outer shape of the robot hand 10 is approximated by an ellipsoid when one or more fingers are extended or fully extended.

[0022] The forward-backward direction can also be referred to as the direction in which the base member 12 of the robot hand 10 extends. The movement of the fingers in the forward-backward direction only needs to have a component in the forward-backward direction (i.e., the y-axis direction) of the movement vector of the fingers, and may include not only movement along the forward-backward direction but also movement in a direction at an angle of 90 degrees or less with respect to the forward-backward direction.

[0023] The mechanical device 50 may be a machine called a robot arm. Furthermore, "directly connected" means connected by contact, and simply "connected" does not only mean "directly connected" but also includes indirectly connected via another object.

[0024] Furthermore, the tip of a finger means the end point of the finger that is opposite the base of the robot hand when the finger is considered to be rod-shaped.

[0025] 1, when the external shape of the robot hand 10 is approximated by an ellipsoid with one or more fingers extended or fully extended, the direction of the longest diameter of the ellipsoid is the y-axis direction shown in FIG. Approximating the robot hand by an ellipsoid may also mean approximating the coordinates of the surface shape of the robot hand (for example, calculating the three-dimensional coordinate points of the entire surface of the robot hand at 1 mm intervals and approximating the three-dimensional coordinates of all of those points) to a three-dimensional ellipse (a prolate sphere or prolate ellipsoid, like a rugby ball) using the least squares method. Furthermore, (4) may be the direction obtained by expanding the major axis direction in three dimensions when the robot hand is considered to have an elongated shape such as a rectangle or ellipse rather than a uniform shape such as a circle or square.

[0026] (Meaning included in forward / backward movement) The forward / backward movement of the finger does not necessarily mean movement completely along any of the directions (1) to (4) (for example, linear movement), but may also mean movement including a directional component of any of the directions (1) to (4). That is, for example, it may be a diagonal movement that includes a left / right movement component in addition to the forward / backward movement, or movement along a curved path that includes a movement component along any of the directions (1) to (4). Furthermore, in order to be considered forward / backward movement, it may be necessary for the main component of the movement to be in any of the directions (1) to (4).

[0027] Furthermore, the forward and backward movement may be a movement accompanied by a change in the angle of the finger orientation.

[0028] (Suction Port) Furthermore, a vacuum (vacuum suction) port may be provided on at least one of the fingers or a member of the robot hand 10 other than the fingers.

[0029] In this embodiment, the fingers 20 and 30 are provided with suction ports 20a, 20b, 30a, and 30b, respectively. As a result, under the control of the control unit 15, air can be sucked through the suction ports by a pump (not shown) or the like, and the resulting negative pressure can be used to suck and hold an object. The suction ports may also be provided on the side surfaces of the fingers, which are on the inside of the robot hand 10, as shown in FIG. 1 . The suction ports may also be provided at the tips of the fingers. The suction ports may also be provided on the side surfaces of the fingers, which are on the outside of the robot hand 10.

[0030] (When the finger portion is not the suction port itself) Note that, when the finger portion has a suction port, the finger portion may be a finger portion that can hold an object only by physically pinching or holding down an object using one or more fingers (i.e., physical pinching or holding down between fingers, or between fingers and parts of the robot hand other than fingers) under the control of the control unit 15, without using a vacuum at the suction port of the finger portion. In this case, the finger portion that pinches or holds down an object does not have to be a finger portion that has a suction port, or it may be a different finger portion.

[0031] (Moving Part of Finger Unit) As in the present embodiment, the finger unit may have one or more drive mechanisms. Furthermore, the drive mechanism of the finger unit may not overlap with the drive mechanism that moves the finger unit in the forward and backward directions (i.e., the drive mechanisms are not common, and if the finger unit has one forward and backward direction movement mechanism 60, it is necessary for the finger unit to have another drive mechanism).

[0032] (Effect of moving the finger portion backward and retracting) The robot hand 10 according to this embodiment has (1) one or more finger portions, or (2) two or more finger portions, or (3) one or more of the two or more finger portions that are movable in the forward and backward directions.

[0033] Here, the above (3) "one or more of the two or more fingers can move in the front-rear direction" means that one or more other fingers can move in the front-rear direction independently of one or more other fingers. In other words, this means that the structure is different from a structure in which all of the other fingers can move in the front-rear direction "simultaneously." This means that the relative positional relationship between the position where one or more fingers exert their function (e.g., the position where the finger presses) and the position where the other one or more other fingers exert their function can be changed in the front-rear direction.

[0034] This allows a certain finger to be retracted from the range of motion of the other finger. Alternatively, when performing a task using one or more fingers A, the other one or more fingers B can be retracted to a position where they do not adversely affect (interfere with) the task. This makes it possible to easily perform a task using the finger A, or to perform a task that would not have been possible without the retraction due to physical interference from the finger B.

[0035] For example, when sucking the top of an object with the suction port of one of the fingers 20, by first moving the other finger 30 backward and retracting it using the forward / backward movement mechanism 60, the object can be held by the robot hand 10 using the suction port of one of the fingers 20 without the other finger 30 interfering with the object (see FIG. 3, which shows the external appearance of the robot hand 10 shown in FIG. 1 when the other finger 30 is moved backward and the top surface of the object 40 is sucked by one of the fingers 20, and the object 40 is about to be held by the robot hand 10).

[0036] This holding method is also effective when there are restrictions on the environment around the object to be held. For example, if there is another object above the object, the other finger 30 can be retracted backward, and one finger 20 can be inserted into the gap between the object and the other object to hold the object.

[0037] (The angle of the finger portion can be changed, and its effect) It is also possible to change the angle of the tip 31 of the finger portion 30. Under the control of the control unit 15, by changing the angle of the tip 31 of the finger portion 30 so that it follows the side of an object, not only the top surface of the object but also the side surface of the object can be sucked. In other words, two or more suction ports can be positioned along surfaces of an object facing different directions to perform vacuuming. This may be possible not only for multiple surfaces of a single object, but also for multiple surfaces of one or more objects with different shapes or multiple surfaces at different angles of two or more objects. In this case, the angle of the tip 31 of the finger portion 30 may be changed under the control of the control unit 15 using shape information, which is one type of object information stored in the memory of the control unit 15, or information on the surface shape of the object detected by a camera or other object detection means such as a camera included in the control unit 15, to follow the side surface of the object. Similarly, the angle of the tip 21 of the finger portion 20 may be changed.

[0038] This allows the object to be held more firmly (see FIG. 4, which shows the appearance of the robot hand 10 shown in FIG. 1 in a state in which one finger 20 is sucking the top surface of the object 40, and the other finger 30 is moving backward while changing the angle of the tip 31 of the finger 30 to suck the side of the object 40).

[0039] Also, Fig. 4 shows one example. That is, in Fig. 4, the surfaces of tip portion 21 and tip portion 31 are aligned to fit the surface of a 90-degree corner of an object, but it is also possible to change the relative angle or relative position of tip portion 21 and tip portion 31 to fit along a surface of any angle or curved surface, not just a surface of a 90-degree corner.

[0040] Furthermore, since the finger portion 30 can be moved in the forward and backward directions, the distance and relative positional relationship between the suction port of the finger portion 20 and the suction port of the finger portion 30 can be changed, making it possible to hold a wider variety of objects.

[0041] Furthermore, the suction port of the tip 31 in Figure 4 can be adjusted in the vertical direction by changing the joint angles of the third rotation axis A3 and the fourth rotation axis A4, allowing the suction port to hold various objects at a position that follows the surface of the object. This adjustment in the vertical direction also involves a shift in the front-to-rear direction, and the front-to-rear movement mechanism 60 is also effective in adjusting this. Note that this change in the vertical position is not limited to changing the joint angle, and it may also be achieved by, for example, using a vertical sliding mechanism.

[0042] (The forward / backward movement mechanism is a slide mechanism that enables sliding movement) Note that, as a specific example of the forward / backward movement mechanism 60, which is a mechanism that moves the finger in the forward / backward direction, a slide mechanism that is configured with a slide drive unit, whose movement becomes sliding movement, is considered as one example. Another specific example is a mechanism that moves in the forward / backward direction by rotational drive. Note that other movement mechanisms may also be used as specific examples of the forward / backward movement mechanism 60.

[0043] For example, it may be a sliding mechanism that slides the finger or the tip of the finger by bending and straightening the finger joint.

[0044] Alternatively, the mechanism may be a slide mechanism that slides the finger or the tip of the finger by using a mechanism that extends or shortens the length of the finger itself.

[0045] The sliding mechanism may have a drive mechanism and may be a mechanism that actively slides, or may be a mechanism that slides by external force. In the case of a mechanism that slides by external force, the sliding mechanism may include a mechanism that can fix the slid position.

[0046] (Retraction of Finger Units, and Expression of Space Occupied by Finger Units) The forward / backward movement mechanism 60 may also be a mechanism that can retract the spatial area of ​​the effect range of one or more fingers moved in the forward / backward direction from the spatial area of ​​the effect range of one or more other arbitrary finger units (i.e., prevent these two spatial areas from overlapping). Here, the spatial area of ​​the effect range of a finger unit may be defined as the spatial area that the finger unit can occupy when the finger unit is moved by a movable unit other than the forward / backward movement mechanism 60 possessed by the finger unit. Furthermore, the retraction of the spatial area of ​​the effect range of a finger unit may target not only the spatial area of ​​the effect range of each finger unit, but also a spatial area that includes the surrounding spatial area (i.e., a space serving as a margin). Here, the spatial area that includes the surrounding spatial area may be a spatial area that extends outside the spatial area of ​​the effect range of the finger unit by the distance from the center of gravity of the spatial area of ​​the effect range of the finger unit to the boundary position of the spatial area of ​​the effect range of the finger unit, or by half that distance.

[0047] Conversely, the retraction of the spatial area of ​​the effective range of each finger may be performed by reducing the spatial area of ​​the effective range of each finger. The reduced spatial area may be obtained by moving the boundary of the spatial area of ​​the effective range of the finger inward by a distance equal to one-third of the distance between the boundary and the center of gravity of the spatial area.

[0048] (Size of Robot Hand) Furthermore, if the thickness of one or more fingers (in FIG. 1, the thickness of each finger in the z direction when each finger is fully extended in the y direction) is small and the width of the finger (in FIG. 1, the x direction) is narrow, this is effective when there are stricter constraints on the environment around the object. For example, a combination of a thickness of 70 mm or less and a width of 120 mm or less is suitable. Another example is a combination of a thickness of 50 mm or less and a width of 100 mm or less. Another example is a combination of a thickness of 40 mm or less and a width of 70 mm or less.

[0049] (Example of control by control unit) As described above, the control unit 15 may perform at least one of the following: (1) control to hold the object 40 by vacuuming the suction ports 20a and 20b, etc. (see Figures 3 and 4); (2) control to vacuum two or more suction ports 20a and 30a, etc. along surfaces of the object in different directions (this may correspond to objects of different shapes and types (see Figure 4 as an example of an object of one shape type)); and (3) control to hold the object 40 only by physically pinching or pressing down the object using one or more of the finger portions 20 and 30, without using vacuuming the suction ports 20a and 20b, etc.

[0050] While the robot hand according to the present disclosure has been described above based on the embodiments and modifications, the present disclosure is not limited to these embodiments and modifications. As long as they do not deviate from the gist of the present disclosure, various modifications that a person skilled in the art could conceive of to the present embodiments and modifications, and other forms constructed by combining some of the components in the embodiments and modifications, are also included within the scope of the present disclosure.

[0051] The robot hand according to the present disclosure can be used as a robot hand that can hold various objects.

[0052] REFERENCE SIGNS LIST 10 Robot hand 11 Connection surface between robot hand and mechanical device 12 Base member of robot hand 15 Control unit 20, 30 Fingers 20a, 20b, 30a, 30b Suction port 21 Tip of finger 20 31 Tip of finger 30 40 Object 50 Mechanical device 51 Part of mechanical device that is directly connected to the robot hand 60 Forward / backward movement mechanism A1 First rotation axis A2 Second rotation axis A3 Third rotation axis A4 Fourth rotation axis

Claims

1. A robot hand having two or more fingers, comprising a mechanism for sliding one or more of the two or more fingers in a forward / backward direction independently of the other one or more fingers, wherein the forward / backward direction is any one of the following: (1) a direction connecting a tip of one of the one or more fingers and the center of gravity of a base member of the robot hand which is a point directly connected to a mechanical device composed of multiple parts; (2) a direction along a normal vector of a connection surface directly connecting the mechanical device and the robot hand; (3) a direction connecting the center of gravity of a part which is directly connected to the robot hand among the multiple parts which make up the mechanical device; or (4) a direction along which the diameter of the ellipsoid which approximates the outer shape of the robot hand with the one or more fingers extended is longest.

2. A robot hand as described in claim 1, further comprising a control unit for controlling the robot hand, at least one of the one or more fingers having a suction port, and the control unit performing the following: (1) control for holding an object by vacuum at the suction port; and (2) control for two or more of the suction ports to vacuum along surfaces of the object that face different directions.

3. The robot hand according to claim 2, wherein the control unit further (3) performs control to hold an object by only physically pinching or pressing down the object using one or more of the fingers, without using a vacuum at the suction ports of the finger portions.

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