Non-parallel 4-node link finger mechanism and gripper

Abstract

To provide a robot finger mechanism and a gripper capable of, by setting a 4-node link to be non-parallel, gripping an article through almost parallel motion in a region of a small input angle, realizing a state where the input angle is greater, and supporting the article or the like with a finger member lowered backward.SOLUTION: A non-parallel 4-node finger mechanism comprises: a first link member connected to rotatable contrapositive points P1 and P2; a second link member connected to rotatable contrapositive points P3 and P4; and a movable finger member fitted to the contrapositive points P2 and P4. The contrapositive points P1 and P3 are fixed points in a body. A square connecting the four contrapositive points P1-P4 does not constitute a parallelogram. By rotating the first link member around the contrapositive point P1 or the second ink member around the contrapositive point P3, the movable finger member is moved. A gripper has this mechanism.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a gripper mechanism equipped with a finger mechanism attached to the end of a robot arm, and in particular to a non-parallel four-link type finger mechanism and gripper. [Background technology]

[0002] FIG. 1 shows an example of an arm robot 1 having a gripper 10 at the tip of an arm 2. The gripper 10 that grips an object is generally configured to have a parallel four-joint link mechanism 11 as shown in FIG. 2 as a drive mechanism (see, for example, Patent Documents 1 to 4). That is, four long link members 12 to 15 that form a parallelogram have four paired joint points P 01 ~P 04 The horizontal link member 12 is pivotally engaged with the joint point P 01 and the antithesis point P 02 The distance L0 is the joint point P 03 and the antithesis point P 04 The distance L0 is equal to the distance L0 between the link member 14 and the joint point P 01 and the antithesis point P 03 The distance H0 is the joint point P of the opposing link member 15. 02 and the antithesis point P 04 Therefore, the link members 12 to 15 have a distance H0 equal to the distance between the paired joint points P 01 ~P 04 Therefore, for example, a movable finger member connected to a link member 15 always moves in parallel in conjunction with a pair of symmetrical movable finger members 16A, 16B as shown in Figures 3(A) and (B), and grasps and releases an object 3 by the parallel movement.

[0003] Figures 3(A) and (B) show a gripper with a pair of parallel four-bar link mechanisms (upper side A and lower side B), with movable finger members 16A and 16B attached to link members 15A and 15B, respectively, and with the rotation of link members 12A and 12B from the state shown in Figure 3(A), the movable finger members 16A and 16B move in parallel to grip the object 3. Figure 3(B) shows the state in which the gripper has gripped the object 3. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-73099 A [Patent Document 2] JP 2020-82239 A [Patent Document 3] JP 2021-133444 A [Patent Document 4] JP 2023-488113 A Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional grippers using the above-mentioned parallel four-bar link mechanism 11 have the advantage that the fingertips always move in parallel, making it easy to grip an object, but they have the problem that when performing an action such as pushing a wall hard, the fingertips hit the wall, causing damage or destruction of the fingers. There is also a problem that the gripper cannot support a heavy, large object. There is also a problem that the gripper cannot grip an object larger than the gap between the fingers.

[0006] The present invention has been made for the above-mentioned reasons, and an object of the present invention is to provide a robot finger mechanism and gripper that can grasp an object with a nearly parallel motion in a range where the input angle is small by making the four-bar link non-parallel, and can also realize a state where the input angle is large, and can support an object with the finger members lowered backward. [Means for solving the problem]

[0007] The present invention relates to a non-parallel four-link type finger mechanism, and the above-mentioned object of the present invention is achieved by the above-mentioned object of the present invention, which is composed of a first link member connected to rotatable pair points P1 and P2, a second link member connected to rotatable pair points P3 and P4, and a movable finger member attached to the pair points P2 and P4, wherein the pair points P1 and P3 are fixed points on the main body, a rectangle connecting the four pair points P1, P2, P3, and P4 does not form a parallelogram, and the movable finger member is moved by rotating the first link member around the pair point P1 or rotating the second link member around the pair point P3. Furthermore, this can be more effectively achieved by having a ratio of the distance between the pair points P3 and P4 to the distance between the pair points P1 and P2 of 0.3 to 1.0, or by having a ratio of the distance from the first link member to the pair point P3 to the distance from the first link member to the pair point P4 of 0.7 to 1.4 in a posture in which the gripping surface of the movable finger member and the pair points 1 and 2 are on the same straight line.

[0008] Furthermore, the present invention relates to a non-parallel four-joint link type gripper, in which the above-mentioned object of the present invention is achieved by arranging two of the non-parallel four-joint link type finger mechanisms described above in a plane symmetrical manner, and by pinching and gripping an object with the gripping surfaces of the two opposing movable finger members, and by comprising a worm gear rotated by a drive shaft, and a worm wheel meshing with the worm gear and having each rotation axis connected to the first link member via the paired joint P3, and by which the two finger members are opened and closed by the rotation of the drive shaft, thereby more effectively achieving the object. Effect of the Invention

[0009] With the non-parallel four-joint link type finger mechanism and gripper of the present invention, an object can be easily grasped with a nearly parallel movement in an area where the finger members are spaced apart only slightly, and a larger opening state can also be easily achieved, making it possible to support an object with the finger members lowered backward.

[0010] Therefore, in addition to grasping an object, the finger members can perform actions such as pushing hard against a wall or supporting a heavy, large object without damaging the finger members. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing an example of an arm robot equipped with a gripper. [Diagram 2] FIG. 1 is a mechanical diagram showing a parallel four-bar link mechanism for explaining a conventional gripper. [Diagram 3] FIG. 1 is a mechanical diagram showing how a conventional gripper grips an object. [Figure 4] FIG. 1 is a mechanical diagram showing an example of a non-parallel four-bar link mechanism of the present invention. [Diagram 5] 1A to 1C are external views showing examples of postures of a parallel four-bar link mechanism for explaining the principle of the present invention. [Figure 6] 1A to 1C are external views showing examples of postures of a non-parallel four-bar link mechanism for explaining the principle of the present invention. [Figure 7] FIG. 2 is a coordinate diagram showing an example of a kinematic model used in the analysis of the present invention. [Figure 8] FIG. 11 is a coordinate diagram showing an example of an analysis result of the present invention. [Figure 9] FIG. 11 is a coordinate diagram showing an example of an analysis result of the present invention. [Figure 10] FIG. 11 is a coordinate diagram showing an example of an analysis result of the present invention. [Figure 11] FIG. 11 is a coordinate diagram showing an example of an analysis result of the present invention. [Figure 12] FIG. 2 is a plan view showing a specific embodiment of the present invention (input angle θ=0°). [Figure 13] FIG. 2 is a plan view showing a specific embodiment of the present invention (input angle θ is small, gripping state). [Figure 14] FIG. 2 is a plan view showing a specific embodiment of the present invention (input angle θ≈45°). [Figure 15] FIG. 2 is a plan view showing a specific embodiment of the present invention (input angle θ≈80°). [Figure 16] FIG. 2 is a plan view showing a specific embodiment of the present invention (input angle θ≈150°). [Figure 17] 17 is a cross-sectional view taken along the line XA-XB in FIG. 16. [Figure 18] FIG. 13 is a side view seen from the LF direction in FIG. 12. [Figure 19] FIG. 2 is a plan view showing a state in which the gripper (asymmetric type) of the present invention grips an object. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In the present invention, instead of the conventional parallel four-joint link mechanism as shown in Fig. 2, a non-parallel four-joint link mechanism 40 in which some or all of the link members 41 to 44 have different lengths and the opposing sides are not parallel, as shown in Fig. 4(A), is used as the basic drive mechanism for the finger mechanism and gripper. Fig. 4(A) shows the connection relationship of the non-parallel four-joint link mechanism 40 in a plan view, and the paired joint point P of the lower link member 41 is 11 and P 12 The distance between 11 , the joint point P of the upper link member 42 13 and P 14 The distance between 12 The left side of the link member 43 has a joint point P 11 and P 13 The distance is H 11 The joint point P of the link member 44 on the right side 12 and P 14 The distance is H 12 FIG. 4B shows the joint point P of the non-parallel four-bar link mechanism 40. 11 and P 13 is fixed to the main body, and the joint point P 12 and P 14 4(B) shows a finger mechanism equipped with finger member 45 having gripping surface 45G. In Fig. 4(B), link member 41 is a driving link that applies rotational force, and link member 42 is a driven link, but link member 42 may be the driving link and link member 41 may be the driven link.

[0013] Next, the basis for achieving the above-mentioned objective finger mechanism and gripper using the non-parallel four-bar link mechanism 40 shown in Fig. 4 will be described with reference to the mechanism diagrams of Fig. 5 and Fig. 6. In Fig. 5 and Fig. 6, a driving link 51 is arranged at paired joint points P1 and P2, a driven link 52 (or a driven link 52A) is arranged at the opposing paired joint points P3 and P4, an intermediate link 53 is arranged at paired joint points P2 and P4, and a finger member 55 is attached to the intermediate link 53. A stationary link 54 is arranged at paired joint points P1 and P3.

[0014] Fig. 5 shows the case of a parallel link mechanism. In the initial position shown in Fig. 5(A), a parallelogram is formed by a driving link 51, a driven link 52, an intermediate link 53, and a stationary link 54. When the driving link 51 is rotated from this initial position to an input angle θ of 90° with the paired joint point P1 as the fulcrum, it becomes an upright singular position as shown in Fig. 5(B). When the input angle θ is increased from the singular position of Fig. 5(B) to more than 90°, it goes beyond the singular position based on the dynamic conditions and branches into position X as shown in Fig. 5(C) or position Y as shown in Fig. 5(D). Position X is a continuation of the parallel movement, while position Y is a position in which the finger members 55 are open in a V-shape. If this position can be realized, it is possible to form a state in which the finger members are lowered backward from the main body surface.

[0015] FIG. 6 shows a non-parallel link mechanism, and in this example, the driven link 52A is slightly shorter than the driving link 51. In the initial position shown in FIG. 6(A), the driving link 51, the driven link 52, the intermediate link 53, and the stationary link 54 form a non-parallelogram. The input angle θ is gradually increased from this initial position, and the driving link 51 rotates around the joint point P1 as a fulcrum. In this case, in a range where the input angle θ is small (approximately 30° or less), the motion is similar to that of a parallel link mechanism as shown in FIG. 6(B) (quasi-parallel opening and closing motion). When the input angle θ is increased from this position, the driven link 52A and the stationary link 54 become upright as shown in FIG. 6(C) just before the input angle θ becomes 90°. Even if the input angle θ is further increased and rotated to a value greater than 90°, the transmission angle of the four-bar link mechanism does not become zero, so the position shown in FIG. 6(D) is achieved, which is close to the position Y in FIG. 5(D). 6(A), a posture close to posture Y can be easily achieved by making the input angle θ greater than 90°, regardless of the dynamic input conditions. Furthermore, by further shortening the length of the driven link 52A, the driven link 52A rotates faster relative to the rotation of the driving link 51, allowing greater opening and closing. However, the shape of the four-bar link mechanism departs from the parallel link mechanism, and the range in which the quasi-parallel opening and closing operation is guaranteed becomes narrower.

[0016] That is, as shown in FIG. 4 (or FIG. 6), the distance L 11 A distance slightly shorter than L 12 By configuring a robot gripper using the non-parallel four-bar link mechanism 40 consisting of the link members 42, an object can be easily grasped with nearly parallel quasi-parallel motion in the area where the opening angle of the finger members is small, and a wide opening / closing state with a large opening angle can also be easily achieved, and an object can also be supported with the finger members lowered backward.

[0017] A kinematic model used for analyzing such a non-parallel link mechanism is shown in FIG. 7, and the analysis results are shown in FIGS. 8 to 11 and will be described.

[0018] As shown in Fig. 7, the kinematic model is placed in the O-xy coordinate system, and the joint point P 21 ~P 24 The coordinates of are (xi, yi) (i=1~4), and the antipodal point P 21 is fixed at the origin O(0,0). 21 and P 22 at distance L 21 (=L 21,22 ) is arranged at the joint point P 23 and P 24 at distance L 23,24 The driven link 42 is disposed at the joint point P 21 and P 23 at distance L 21,23 The stationary link is placed at the joint point P 21 and P 24 at distance L 21,24 The intermediate link is arranged, and the finger member 45 is attached to the intermediate link, and the fingertip coordinate of the tip of the finger member 45 is Pt. The angle that the driving link 41 makes with the x-axis is defined as the input angle θ, and the angle that the grip surface 45G of the finger member 45 makes with the x-axis is defined as the fingertip angle φ. 22 The initial value of the fingertip coordinate Pt is set to (1, 0), the initial value of the fingertip coordinate Pt is set to (2, 0), and the distance L of the driving link 41 is set to (1, 0). 21 (= L21,22 ) is set to “1” for convenience.

[0019] For such a four-bar link mechanism, kinematic analysis was performed while changing the mechanism constants (x3, y3) and (x4, y4). As an example, a search was conducted for a set of mechanism constants that satisfy the following conditions (1) to (4). (1) Range of motion conditions: The driving link 41 can rotate 150° counterclockwise from the initial position. That is, the following formula 1 is satisfied. (Number 1) 0°≦θ≦150° (2) Shape requirements: It is a non-parallel four-bar linkage mechanism rather than a parallel four-bar linkage mechanism. (3) Wide opening and closing conditions: When the driving link 41 rotates counterclockwise by 150° from the initial position, the gripping surface 45G of the finger member 45 opens by 90° or more from the horizontal plane. That is, it is the following formula (2). (Formula 2) Input angle θ = 150° → Finger tip angle φ ≧ 90° (4) Pseudo parallel opening and closing condition: Before the driving link 41 rotates counterclockwise by 30° from the initial position, the gripping surface 45G of the finger member 45 does not tilt by ±n° (n = 1, 2, 3, 4, 5) or more from the horizontal plane. "n" is the allowable finger tip angle and is the following formula (3).

[0020]

Formula

[0021] Next, the antithesis point P 24 When the position of the pair of points is fixed, P 23 The distribution diagram of the position of the pair point P is shown in Fig. 10 and Fig. 11. 24 is fixed at (x4, y4) = (0.3, 0.4), and Fig. 11 shows the antipodal point P 24 In this case, the joint point P when the four-bar link mechanism becomes a parallel link mechanism is fixed at (x4, y4) = (0.5, 0.7). 23 The position of the parallel link point is also shown in each figure. 23 and P 24 At a position where the distance between the two points is slightly shorter than "1", there is a pair of points P that satisfy n≦1. 23 8 and 9. However, in FIG. 10, there is no solution that satisfies the above conditions (1) to (4) near the parallel link point. 23 and P 24 The distance between the paired points P is slightly shorter than "1". 23 As an example of a region where no solution exists, a motion analysis of the link mechanism when (x4, y4) = (0.3, 0.4) and (x3, y3) = (0.65, 0.4) shows that the fingertips are almost parallel in the range of 0°≦θ≦90°, but do not open more than 90° when the input angle θ = 150°. In other words, the pseudo-parallel opening and closing conditions are met, but the large opening and closing conditions are not met.

[0022] Also, the antithesis point P 23 and P 24 The initial position of the maximum fingertip opening and closing angle φmax when the input angle θ = 150° for the distance is (x4, y4) = (1.0, 0.7), (x3, y3) = (0.0, 0.7). 24 When the side is shortened, the counter joint point P 23In either case, the shorter the link dimension is from "1", that is, the more the shape deviates from the parallel link, the larger the opening and closing angle becomes. From these findings, the key to achieving both the pseudo-parallel opening and closing condition and the large opening and closing condition is the joint point P. 23 and P 24 It appears that the balance between the two evaluation conditions for the distance is what determines the result. In other words, the following trends (a) and (b) are observed. (a) In the case of a parallel link mechanism, when the driven link is slightly shorter than the driving link, it tends to be easier to achieve both the pseudo-parallel opening / closing condition and the large opening / closing condition. (b) When the driven link is made shorter than the driving link in the parallel link mechanism, the opening angle of the gripper tends to increase. From the above, it can be said that to obtain a non-parallel four-link type finger mechanism that achieves both pseudo-parallel opening and closing and large opening and closing, the upper link should be shortened by a ratio of about 0.3 to 1.0, and the y coordinate of the paired point of the upper link should be in a ratio of about 0.7 to 1.4.

[0023] Based on the above results, the link dimension ratio of the non-parallel four-bar link mechanism is defined. 21 and the antithesis point P 22 The distance between 21 The joint point P of the upper link member 42 is 23 From the antipodes point P 24 Distance to L 22 Let the distance be L 21と Distance L 22 The relationship is designed to satisfy the following formula 5. (Number 5) L 22 =L 21 ×a 0.3≦a<1.0 Also, the antithesis point P 21 and the antithesis point P 22 From the link member 41 that connects 23 Distance to 23 However, from the link member 41 to the joint point P 24 Distance to 24 is designed to satisfy the relationship of the following formula 6. (Number 6) D 23 =D 24 ×b 0.7≦b≦1.4 The above is a description of the principle of the present invention. Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

[0024] 12 to 16 show the non-parallel four-bar link type gripper 100 of the present invention in plan views in states corresponding to the input angle θ of the gripper 100, with FIG. 12 showing a state in which the gripping surfaces 110AG and 110BG of the finger members 110A and 110B are in contact with each other, that is, a state in which the input angle θ of the gripper 100 is 0°. Also, FIG. 13 shows a state in which an object 130 is gripped during the above-mentioned pseudo-parallel opening and closing, FIG. 14 shows a state in which the input angle θ is ≈ 45°, FIG. 15 shows a state in which the input angle θ is ≈ 80°, and FIG. 16 shows a large opening and closing state in which the input angle θ is ≈ 150°. Also, FIG. 17 shows a state in which the input angle θ is ≈ 45° in FIG. 16, FIG. 18 shows a state in which the input angle θ is ≈ 80°, and FIG. 19 shows a state in which the input angle θ is ≈ 150°. A -X B 12. FIG. 18 shows a left side view taken along the line LF in FIG.

[0025] For convenience, in this example, the upper part of the drawing is taken as the tip of the gripper 100, and the member on the left side of the drawing with respect to the center line CL is given the symbol A, and the member on the right side of the drawing is given the symbol B, but the structure is symmetrical. The gripper 100 in this example is a symmetrical gripper that is symmetrical with respect to the center line CL, and as shown in Fig. 14, the opening angle of the link member 112A or 112B with respect to the center line CL is the input angle θ, and the opening angle of the gripping surface 110AG or 110BG is the fingertip angle φ.

[0026] The tip portion 101P is almost flat (or has a gentle curved shape) and has a recess in the center along the center line CL. The body 101 has a rotatable joint point P 1A and P 1B One end of each of the pair of elongated drive link members 112A and 112B is connected to the upper and lower joint points P via the rotation shafts 111AJ and 111BJ. 1A and P 1BWorm wheels 111A and 111B that mesh with the worm gear 102 are connected to the respective rotation shafts 111AJ and 111BJ in opposing relation to each other on the left and right. The worm gear 102 is rotated in the NR or RV direction by a drive shaft 103 that is connected to a drive mechanism (not shown), and the rotation of the worm gear 102 rotates the worm wheels 11A and 111B in the opposite directions. The rotation of the worm wheels 11A and 111B rotates the driving link members 112A and 112B that are connected to the rotation shafts 11AJ and 111BJ at the paired joint points P 1A and P 1B It rotates around the (rotation axis) as a fulcrum.

[0027] The other end of each of the driving link members 112A and 112B is a pivotable joint point P 2A and P 2B The main body 101 is pivotally connected to the bottom of the finger members 110A and 110B, which are triangular in plan and U-shaped in cross section, via the joint points P. 1A and P 1B In the vicinity of the outside of 3A and P 3B is provided, and the counter joint point P 3A and P 3B A pair of elongated driven link members 113A and 113B are connected to the upper and lower ends of the finger members 110A and 110B, and the other ends of the driven link members 113A and 113B are rotatably connected to the inner surfaces of the finger members 110A and 110B, respectively.

[0028] As shown in the cross-sectional view of Fig. 17 and the side view of Fig. 18, the outsides of the finger members 110A and 110B are sandwiched between driving link members 112A and 112B arranged in a pair above and below, respectively, and driven link members 113A and 113B are arranged in a pair above and below the main body 101 and sandwich the inner surfaces of the finger members 110A and 110B, respectively. That is, on side A, the arrangement from the top is the upper driving link member 112A, the ceiling part of the finger member 110A, the upper driven link member 113A, the main body 101, the lower driven link member 113A, the bottom part of the finger member 110A, and the lower driving link member 112A. Similarly, on side B, the arrangement is, from the top, upper drive link member 112B, the ceiling portion of finger member 110B, upper driven link member 113B, main body 101, lower driven link member 113B, the bottom portion of finger member 110B, and lower drive link member 112B.

[0029] In this configuration, for example, the initial state is the state of input angle θ=0° in Fig. 12. That is, the gripping surfaces 110AG and 110BG of the pair of finger members 110A and 110B are in contact with each other. When the drive shaft 103 is rotated from this state, for example, in the NR direction by the drive mechanism, the worm wheels 111A and 111B meshing with the worm gear 102 are rotated in the opposite directions, and the driving link members 112A and 112B connected to the worm wheels 111A and 111B by the rotation shafts 111AJ and 111BJ rotate in the opposite directions, respectively, so that the paired joint points P 1A and P 1B 15 or 16, finger members 110A and 110B are lowered below the tip plane of the main body, so that a substantially flat tip portion 110P of main body 101 is exposed, and thus tip portion 110P can perform powerful work such as pressing without being hindered by finger members 110A and 110B, even though it is a gripper.

[0030] When the drive shaft 103 is rotated in the opposite RV direction by the drive mechanism from the wide open / close state of FIG. 16, the input angle θ gradually decreases, and the state returns to the closed state of FIG. 12 via the state of FIG. 15, the state of FIG. 14, and the state of FIG. 13.

[0031] In addition, when the gripper 100 grips the object 130, the object 130 can be gripped and released in a quasi-parallel motion by opening and closing within a small range of the input angle θ (approximately 30° or less) as shown in FIG. 13.

[0032] In this embodiment, an example is shown in which link members are provided on the top and bottom of the main body 101 in order to increase the strength of the gripper 100 and strengthen its gripping force, but a configuration in which only the top or bottom is provided may be used to reduce weight.

[0033] 12 to 18 are examples of grippers having a plane-symmetric configuration, but as shown in FIG. 19, the gripper may have a configuration in which an object 130 is gripped by one non-parallel four-joint link mechanism and fixed finger members 141 extended from the main body. [Explanation of symbols]

[0034] 1 Arm Robot 2 Arm 3 objects 10 Gripper 11 Parallel four-bar link mechanism 12~15 Link parts 16A, 16B Movable finger members 40 Non-parallel four-bar link mechanism 41~44 Link members 45 Finger member 100 Gripper 101 Main unit 102 Worm Gear 103 Drive shaft 110A, 110B Finger members 111A, 111B Worm Wheel 112A, 112B Driving link member 113A, 113B Driven link member 130 Object 141 Fixed finger member

Claims

1. A first link member connected to rotatable joint points P1 and P2; A second link member connected to the rotatable joint points P3 and P4; A movable finger member attached to the paired joints P2 and P4; It is composed of The paired joints P1 and P3 are fixed points on the main body, The quadrilateral connecting the four paired points P1, P2, P3, and P4 does not form a parallelogram, A non-parallel four-joint link type finger mechanism, characterized in that the movable finger member is moved by rotating the first link member about the paired joint point P1 or rotating the second link member about the paired joint point P3.

2. 2. The non-parallel four-link type finger mechanism according to claim 1, wherein the ratio of the distance between the paired joints P3 and P4 to the distance between the paired joints P1 and P2 is 0.3 to 1.

0.

3. 3. The non-parallel four-joint link type finger mechanism according to claim 1 or 2, wherein a ratio of a distance from the first link member to the pairing point P3 to a distance from the first link member to the pairing point P4 is 0.7 to 1.4 in a posture in which the gripping surface of the movable finger member, the pairing point 1, and the pairing point 2 are on the same straight line.

4. The non-parallel four-joint link type finger mechanism according to any one of claims 1 to 3 is configured to be arranged symmetrically on a plane, A non-parallel four-joint link type gripper, characterized in that an object is pinched and gripped between the gripping surfaces of the two opposing movable finger members.

5. a worm gear rotated by a drive shaft; a worm wheel that meshes with the worm gear and has a rotation axis that is connected to the first link member via the paired joint point P3; It is composed of 5. The non-parallel four-joint link type gripper according to claim 4, wherein the two finger members are opened and closed by rotation of the drive shaft.

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