Robot hand mechanism

Abstract

To provide a hand mechanism that is configured so that fingertips of three fingers brought into 120° states can be concentrated at one point to grip a comparatively small object.SOLUTION: A hand mechanism 10A comprises: a fixed finger 11 fixed to a base part 20 so that the finger points to a predetermined reference point; two turning fingers 12 and 13; a finger turning mechanism 30, provided among the turning fingers 12 and 13 and the base part 20, which enables the turning fingers 12 and 13 to turn in an XY plane; and finger direction determining mechanisms 34 and 36, provided among the turning fingers 12 and 13 and the base part 20, which determines directions of the turning fingers 12 and 13. In a 120° state. the turning fingers 12 and 13 point to the reference point, and a line connecting the fixed finger 11 to the reference point is identical in length to a line connecting the turning fingers 12 and 13 to the reference point.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hand mechanism that is attached to a robot arm for use, and more particularly to a hand mechanism that has three or more fingers. [Background technology]

[0002] Conventionally, various hand mechanisms have been used depending on the purpose. For example, the hand mechanism described in Non-Patent Document 1 is used as a hand mechanism intended to grasp objects of various sizes and shapes.

[0003] As shown in Figure 9, the hand mechanism 100 described in Non-Patent Document 1 comprises a base 101 that is rotatably attached to the tip of a robot arm, a fixed finger 102 fixed to the base 101, and two pivoting fingers 103 and 104 attached to the base 101 so as to be able to pivot within a plane parallel to the mounting surface (bottom surface) of the base 101.

[0004] As shown in FIG. 10 , the three fingers 102, 103, and 104 can be in a 0° state where the three fingers 102, 103, and 104 are aligned in a row; a 120° state where the two pivoting fingers 103 and 104 are each rotated 120° from the 0° state; and a 180° state where the two pivoting fingers 103 and 104 are each rotated an additional 60° from the 120° state. The 120° state is suitable for grasping relatively small objects. In the 120° state, the object can be grasped by pinching with the tips (fingertips) of the three fingers 102, 103, and 104. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] "Multipurpose Robot Hand BarrettHand BH8-282", [online], Nihon Binary Co., Ltd., [Retrieved July 19, 2021], Internet <URL: http: / / www.nihonbinary.co.jp / Products / Robot / BarrettHand.html> Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional hand mechanism 100 described above, when the three fingers 102, 103, and 104 are bent uniformly at a 120° angle, the three fingertips do not converge at a single point. This is because, no matter how the two pivoting fingers 103 and 104 are rotated, they are not symmetrical about the pivot axis 105 of the base 101 relative to the robot arm. Therefore, when attempting to gather the three fingertips at a single point to grasp a relatively small object with this hand mechanism 100, the finger opening / closing drive mechanism for the pivoting fingers, the fixed fingers, or both must be given two or more degrees of freedom to appropriately adjust the degree of opening and closing of the fingers. This contributes to the complexity of the finger mechanism and control.

[0007] The present invention has been made in consideration of the above circumstances, and its object is to provide a hand mechanism that can gather the fingertips of three fingers in a 120° position at one point and grasp a relatively small object, even if the finger opening / closing drive mechanism for each finger has only one degree of freedom. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a hand mechanism that is attached to a robot arm and used, the hand mechanism comprising: a base having an attachment surface that is attached to the tip of the robot arm; fixed fingers that are fixed to the base so as to face a predetermined reference point; two pivoting fingers; finger rotation mechanisms that are provided between each of the two pivoting fingers and the base and enable the pivoting fingers to rotate within a reference plane that is parallel to the attachment surface; and a finger direction determination mechanism that is provided between each of the two pivoting fingers and the base and determines the orientation of the pivoting fingers, wherein the fixed fingers and the two pivoting fingers are: (1) 2 The finger can assume three positions: (1) a 0° state in which the fixed finger and the two pivoting fingers are aligned so that the fixed finger is positioned between the two pivoting fingers; (2) a 120° state in which the line connecting the fixed finger to the reference point and the line connecting each of the two pivoting fingers to the reference point form an angle of 120°; and (3) a 180° state in which each of the two pivoting fingers faces directly toward the two pivoting fingers in the 0° state. In the 120° state, the pivoting finger faces the reference point, and the line connecting the fixed finger to the reference point and the line connecting the pivoting finger to the reference point are the same length.

[0009] The finger rotation mechanism of the hand mechanism can include, for example, a motor having an output shaft fixed to a base and extending in a direction perpendicular to a reference plane, and a rotating arm having one end and the other end, one end of which is fixed to the output shaft via a reducer and the other end of which is rotatably connected to the rotating finger, and the output shaft is located on a line extending from the rotating finger in a 0° state and parallel to a line connecting the fixed finger and the reference point.

[0010] The finger direction determination mechanism of the hand mechanism can be configured, for example, to include a guide flap rotatably connected to a base, and a sliding portion that is slidable relative to the guide flap and fixed to the pivoting finger, and the rotation axis of the guide flap is at the intersection of a line connecting the pivoting finger, which is in a 120° position, to a reference point and a parallel line.

[0011] The hand mechanism may further include an additional fixed finger fixed to the base so as to face the reference point, the additional fixed finger facing directly opposite the fixed finger, and a line connecting the fixed finger to the reference point and a line connecting the additional fixed finger to the reference point may be the same length.

[0012] The base of the hand mechanism may be pivotally attached to the tip of a robot arm, in which case a reference point can be set on the pivot axis of the robot arm. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a hand mechanism that can grasp a relatively small object by gathering the tips of three fingers, which are angled at 120°, at one point. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a perspective view of a hand mechanism according to an embodiment of the present invention in a 120° state. [Figure 2] FIG. 2 is a perspective view of a hand mechanism according to an embodiment of the present invention in a 0° state. [Figure 3] FIG. 2 is a perspective view of a hand mechanism according to an embodiment of the present invention in a 180° state. [Figure 4] FIG. 2 is an exploded perspective view of a hand mechanism according to an embodiment of the present invention. [Figure 5] 1A and 1B are schematic plan views showing the positional relationships of the main components constituting the hand mechanism according to an embodiment of the present invention, in which (A) is a schematic plan view in a 0° state, (B) is a schematic plan view in a 120° state, and (C) is a schematic plan view in a 180° state. [Figure 6] 1A and 1B are plan views of a hand mechanism according to an embodiment of the present invention, in which (A) is a plan view in a 0° state, (B) is a plan view in a 120° state, and (C) is a plan view in a 180° state. [Figure 7] FIG. 10 is a perspective view of a hand mechanism according to a first modified example of the present invention. [Figure 8] FIG. 10 is a perspective view of a hand mechanism according to a second modified example of the present invention. [Figure 9] FIG. 1 is a perspective view of a conventional hand mechanism. [Figure 10] FIG. 10 is a plan view showing the turning operation of a conventional hand mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of a hand mechanism according to the present invention will be described with reference to the accompanying drawings.

[0016] [Example] 1 to 4 show a hand mechanism 10A according to an embodiment of the present invention, which has three fingers (a fixed finger 11 and two pivoting fingers 12 and 13) of the same structure. The hand mechanism 10A is attached to the tip of a robot arm (not shown) so that it can rotate about a pivot axis R1. In addition to the 120° position shown in FIGS. 1 and 6(B), the hand mechanism 10A can also assume the 0° position shown in FIGS. 2 and 6(A) and the 180° position shown in FIGS. 3 and 6(C).

[0017] As shown in Fig. 1, the hand mechanism 10A includes a base 20 having a shape symmetrical with respect to the YZ plane including the rotation axis R1. The base 20 has a mounting surface 20a parallel to the XY plane and two motor housing chambers 21, 21. Each motor housing chamber 21 houses a motor having an output portion rotatable about an output shaft R2 (see Fig. 4) extending in the Z direction. An appropriate reducer 22 is provided at the output portion of each motor.

[0018] The hand mechanism 10A further includes a substantially plate-shaped fixed finger support part 23 that rotatably supports the fixed finger 11 at its upper end. The fixed finger 11 faces the pivot axis R1 and rotates relative to the fixed finger support part 23 by the action of a fixed finger opening / closing drive mechanism 24 provided on the outward main surface of the fixed finger support part 23. In other words, the fixed finger 11 opens and closes by the action of the fixed finger opening / closing drive mechanism 24. In this embodiment, the fixed finger opening / closing drive mechanism 24 has one degree of freedom.

[0019] In this specification, the combination of the fixed finger 11 and the fixed finger support portion 23 may be referred to as the "fixed finger."

[0020] The hand mechanism 10A further includes two swivel arms 30, 30 extending within the XY plane. Each swivel arm 30 has one end and the other end, one end of which is fixed to the output portion of a motor via a reducer 22, and the other end of which is rotatably connected to a connecting portion 33 (swivel finger support portion 31) described below. In other words, each swivel arm 30 is rotatable about an output axis R2 relative to the base 20, and is also rotatable about a rotation axis R3 (see FIG. 4) relative to the connecting portion 33 (swivel finger support portion 31).

[0021] When the motor rotates in a certain direction, the swivel arm 30 rotates in the XY plane by an angle corresponding to the amount of rotation and the reduction ratio of the reducer 22, and the positional relationship (state) of the three fingers 11, 12, and 13 changes from 0° state to 120° state to 180° state. On the other hand, when the motor rotates in the opposite direction, the swivel arm 30 rotates in the XY plane by an angle corresponding to the amount of rotation and the reduction ratio, and the positional relationship of the three fingers 11, 12, and 13 changes from 180° state to 120° state to 0° state.

[0022] The hand mechanism 10A further includes a generally plate-shaped pivoting finger support portion 31 that rotatably supports the pivoting finger 12 at its upper end. The pivoting finger support portion 31 has a connecting portion 33 protruding from its inward main surface, and is pivotally connected to the pivoting arm 30 by this connecting portion 33. The pivoting finger 12 rotates relative to the pivoting finger support portion 31 by the action of a pivoting finger opening / closing drive mechanism 32 provided on the outward surface of the pivoting finger support portion 31. In other words, the pivoting finger 12 opens and closes by the action of the pivoting finger opening / closing drive mechanism 32. In this embodiment, the pivoting finger opening / closing drive mechanism 32 has one degree of freedom.

[0023] Naturally, the hand mechanism 10A also includes a substantially plate-shaped finger support portion 31 that rotatably supports the finger 13 at its upper end.

[0024] In this specification, the combination of the pivoting finger 12 and the pivoting finger support portion 31, and the combination of the pivoting finger 13 and the pivoting finger support portion 31 may be referred to as a "pivoting finger."

[0025] The hand mechanism 10A further includes two generally plate-shaped guide flaps 36, 36 extending in the Z direction. Each guide flap 36 has two connecting portions 37, 38 protruding from one of its main surfaces (see FIG. 4), which connect the flap 36 to the base 20 in a rotatable manner. That is, each guide flap 36 is rotatable about a rotation axis R4 (see FIG. 4) relative to the base 20. Each guide flap 36 also includes two parallel guide rods 35, 35 extending along the one of its main surfaces. Both ends of the two guide rods 35, 35 are fixed to the main surface of the guide flap 36.

[0026] The hand mechanism 10A further includes two sliding units 34. Each sliding unit 34 has two through tunnels 34a into which guide rods 35 are inserted, allowing the sliding units 34 to slide freely along the guide rods 35. A pivoting finger support unit 31 is fixed to the end of each sliding unit 34 closer to the connecting units 37 and 38, forming a right angle with each other. This allows the pivoting fingers 12 and 13 supported by the pivoting finger support unit 31 to always face in the same direction as the sliding direction of the sliding unit 34 (i.e., the extension direction of the guide rods 35).

[0027] Next, a design method for the hand mechanism 10A will be described with particular reference to Figure 5. The fixed finger 11 in the figure includes a fixed finger support section 23 and a fixed finger open / close drive mechanism 24. The pivoting fingers 12 and 13 in the figure include a pivoting finger support section 31, a pivoting finger open / close drive mechanism 32, a connecting section 33, and a sliding section 34. The guide flap 36 in the figure includes guide rods 35 and connecting sections 37 and 38.

[0028] First step: determine the actual dimensions of the base 20, fixed finger 11 and pivoting finger 12, 13.

[0029] Second step: Draw a circle C centered on the pivot axis R1. At this time, the size of the circle C is made to correspond to the actual dimensions of the base 20. The position of the pivot axis R1 corresponds to the "reference point" of the present invention.

[0030] Third step: The fixed finger 11 is drawn so as to be in contact with the circle C. At this time, the width direction dimension W of the fixed finger 11 is made to correspond to the actual dimension.

[0031] Fourth step: Assuming a 0° state, the pivoting fingers 12 and 13 are drawn on both sides of the fixed finger 11. At this time, the width dimension W of the pivoting fingers 12 and 13 is set to be the same as the width dimension W of the fixed finger 11.

[0032] Fifth step: The widthwise center of the pivot fingers 12, 13 in the 0° state is set as the position of the rotation axis R3 in the 0° state (see Figure 5(A)), and two parallel lines L2, L2 extending from this position (R3) and parallel to the line L1 are drawn.

[0033] Sixth step: Draw two lines L3, L3 that pass through the reference point (R1) and form 120° with respect to the line L1.

[0034] Seventh step: The intersection of line L3 and circle C is set as the position of rotation axis R3 in the 120° state (see FIG. 5(B)), and the intersection of line L3 and line L2 is set as the position of rotation axis R4.

[0035] Eighth step: The point on the line L2 where the distance from the position of the rotation axis R3 in the 0° state and the distance from the position of the pivot axis R3 in the 120° state are equal is determined as the position of the output axis R2.

[0036] Ninth step: The dimensions of the swivel arm 30 are determined based on the distance between the position of the rotation axis R2 and the position of the rotation axis R3.

[0037] By determining the positions of output axis R2 and rotation axes R3 and R4 in this manner, in the 120° state, the three fingers 11, 12, and 13 face toward the reference point (R1), and the distances from the reference point (R1) to each of the fingers 11, 12, and 13 become equal (see FIG. 5(B)). That is, according to the above steps 1 to 9, it is possible to realize hand mechanism 10A that can pinch-like grasp an object on rotation axis R1 in the 120° state.

[0038] FIG. 6 is a plan view of the hand mechanism 10A (with the three fingers 11, 12, and 13 omitted) corresponding to FIG. 5 . As can be seen from FIG. 6 , in this embodiment, the motor, the reducer, and the swivel arm 30 enable the swivel fingers 12 and 13 to rotate in a plane parallel to the mounting surface 20 a. Therefore, in this embodiment, the motor, the reducer, and the swivel arm 30 correspond to a “finger rotation mechanism.” Furthermore, in this embodiment, the orientation of the swivel fingers 12 and 13 is determined not by how much the swivel arm 30 has rotated relative to the base 20, but by how much the guide flap 36 has rotated relative to the base 20. Therefore, in this embodiment, the guide flap 36 and the sliding portion 34 that slides along it correspond to a “finger direction determination mechanism.”

[0039] [First Modification] Although the embodiments of the hand mechanism according to the present invention have been described above, the hand mechanism according to the present invention is not limited to these, and may have a configuration such as hand mechanism 10B shown in FIG.

[0040] The hand mechanism 10B of this modified example has three fingers of the same structure (a fixed finger 11 and two pivoting fingers 12, 13), and is attached to the tip of a robot arm (not shown) so that it can rotate around a pivot axis R1.

[0041] 7, the hand mechanism 10B includes a base 40 having a shape symmetrical with respect to the YZ plane including the rotation axis R1, a fixed finger support part 41 supporting the fixed finger 11 at its upper end, two pivoting finger support parts 42 supporting the pivoting fingers 12 and 13 at their upper ends, two guide rods 44, and a guide plate 50 having a surface 50a parallel to the XY plane. Although not shown, the hand mechanism 10B also includes a fixed finger opening / closing drive mechanism provided on the fixed finger support part 41 and a pivoting finger opening / closing drive mechanism provided on the pivoting finger support part 42.

[0042] Each guide rod 44 has a connecting portion 43, and is rotatably connected to the base portion 40 by this connecting portion 43. In other words, each guide rod 44 is rotatable relative to the base portion 20 around a rotation axis R4.

[0043] The guide plate 50 has two guide grooves 51, 51 formed on the surface 50a. The arc shape of each guide groove 51 is the same as the trajectory of the rotation axis R3 when the pivoting fingers 12, 13 are rotated from the 0° position to the 180° position in the hand mechanism 10A according to the embodiment (see FIG. 5). The arc shape of each guide groove 51 can also be said to be an arc with a central angle of 180° centered on the rotation axis R2. Each guide groove 51 engages with a protrusion provided at the lower end of the pivoting finger support portion 42 to guide the protrusion.

[0044] The pivoting finger support portion 42 and the guide rod 44 constitute a linear actuator. That is, the pivoting finger support portion 42 is linearly movable along the guide rod 44. When the linear actuators (42, 44) are activated and the pivoting finger support portion 42 moves away from the rotation axis R3, the guide rod 44 rotates around the rotation axis R4, and the pivoting finger support portion 42 moves along the guide groove 51 and approaches the fixed finger support portion 41. On the other hand, when the linear actuators (42, 44) are activated and the pivoting finger support portion 42 moves closer to the rotation axis R3, the guide rod 44 rotates around the rotation axis R4, and the pivoting finger support portion 42 moves along the guide groove 51 and moves away from the fixed finger support portion 41.

[0045] In this manner, in this modification, the linear actuators (42, 44) are actuated to change the relative positions of the three fingers 11, 12, and 13. In this modification, the linear actuators (42, 44) and the guide groove 51 correspond to the "finger rotation mechanism." In addition, in this modification, the linear actuators (42, 44) correspond to the "finger direction determination mechanism."

[0046] Like the hand mechanism 10A according to the embodiment, the hand mechanism 10B according to this modification can grip an object by pinching it on the rotation axis R1 in the 120° state.

[0047] [Second Modification] The hand mechanism according to the present invention may have a configuration like a hand mechanism 10C shown in FIG.

[0048] The hand mechanism 10C according to this modification is different from the hand mechanism 10B in that it further includes another fixed finger 14, further includes a fixed finger support part 45 that supports the fixed finger 14, and the shape of the base 40 allows for attachment of the fixed finger support part 45, but is otherwise the same as the hand mechanism 10B. The fixed finger 14 is provided directly opposite the fixed finger 11, and the distance from the pivot axis R1 to the fixed finger 14 is equal to the distance from the pivot axis R1 to the fixed finger 11.

[0049] According to the hand mechanism 10C of this modification, an object can be grasped by pinching it on the rotation axis R1 using the three fingers 11, 12, and 13 and the fixed finger 14 that are in the 120° position.

[0050] [Other variations] The hand mechanism according to the present invention may be mounted on a robot arm so as not to be rotatable. Each of the fixed fingers 11 and 14 and the pivoting fingers 12 and 13 may have one or more joints. The fixed finger opening / closing drive mechanism 24 and the pivoting finger opening / closing drive mechanism 32 may have two or more degrees of freedom. [Explanation of symbols]

[0051] 10A, 10B, 10C Hand mechanism 11 fixed finger 12,13 swivel finger 20 base 21 Motor Containment Room 22 Reducer 23 Fixed finger support part 24 Fixed finger opening and closing drive mechanism 30 Swivel Arm 31 Swivel finger support 32 Swivel finger opening / closing drive mechanism 33 Connecting part 34 Sliding part 35 Guide rod 36 Guide flap 37,38 Connection part 40 base 41 Fixed finger support 42 Swivel finger support 43 Connecting part 44 Guide rod 45 Fixed finger support part 50 Guide plate 51 Guide groove

Claims

1. A hand mechanism used by being attached to a robot arm, a base having a mounting surface attached to the tip of the robot arm; a fixed finger fixed to the base so as to face a predetermined reference point; Two pivoting fingers, a finger rotation mechanism provided between each of the two pivoting fingers and the base, which enables the pivoting fingers to rotate within a reference plane parallel to the mounting surface; a finger direction determining mechanism provided between each of the two pivoting fingers and the base, the finger direction determining mechanism determining the orientation of the pivoting fingers; Equipped with The fixed finger and the two pivoting fingers are (1) A 0° state in which the fixed finger and the two pivoting fingers are aligned so that the fixed finger is located between the two pivoting fingers; (2) a 120° state in which a line connecting the fixed finger and the reference point and a line connecting each of the two pivoting fingers and the reference point form an angle of 120°; (3) The two pivoting fingers are in a 180° state facing each other in the 0° state. You can take In the 120° state, the pivoting finger faces the reference point, and a line connecting the fixed finger and the reference point and a line connecting the pivoting finger and the reference point are the same length; The finger rotation mechanism is a motor fixed to the base and having an output shaft extending in a direction perpendicular to the reference plane; a pivot arm having one end and the other end, the one end being fixed to the output shaft via a reducer and the other end being rotatably connected to the pivot finger; Including, The output shaft is on a line extending from the pivoting finger in the 0° state and parallel to a line connecting the fixed finger and the reference point, The finger direction determination mechanism includes: a guide flap pivotally connected to the base; a sliding portion slidable relative to the guide flap and fixed to the pivot finger; Including, The rotation axis of the guide flap is at the intersection of the line connecting the pivot finger, which is in the 120° state, with the reference point and the parallel line. A hand mechanism characterized by:

2. further comprising an additional fixed finger fixed to the base so as to face the reference point; The additional fixed finger is positioned directly opposite the fixed finger, and the line connecting the fixed finger to the reference point and the line connecting the additional fixed finger to the reference point are the same length.

2. The hand mechanism according to claim 1.

3. the base is pivotally attached to the tip of the robot arm, The reference point is on a pivot axis of rotation relative to the robot arm.

3. The hand mechanism according to claim 1 or 2.

Images