JP7599796B2 - Pad for robot hand, and robot hand - Google Patents

Description

The present invention relates to a robot hand pad that is provided on a robot hand that grasps an object of an articulated robot used for transporting, assembling, etc., of an object, and to the robot hand.

In recent years, the manufacturing process of various products has become increasingly automated in the industrial world, and it has become common for industrial robots to carry out tasks such as transporting, assembling, and inspecting goods instead of workers. For example, one type of industrial robot that is widely used is the articulated robot, which is capable of movements similar to those of a human arm.

Articulated robots can move their tip along the axes of a three-dimensional Cartesian coordinate system (X-axis, Y-axis, Z-axis) and rotate their tip along the U-axis around the X-axis, the V-axis around the Y-axis, and the W-axis around the Z-axis, enabling them to perform a variety of complex movements. For this reason, articulated robots are highly versatile and are frequently used in a wide range of fields.

Articulated robots that can move objects or change their posture are equipped with a robot hand (gripper) at the tip to grasp objects. The robot hand is, for example, composed of multiple fingers, and can grasp an object by arranging the fingers around the object and moving the fingers closer to each other (see, for example, Patent Documents 1 to 4).

JP 2011-115914 A JP 2011-131341 A JP 2005-153114 A JP 2020-78857 A

When attempting to grasp a heavy object such as a casting that has a rough curved surface with the flat fingers of a robot hand, the fingers and the object come into point contact. In this case, when the object is lifted, it may rotate around the contact point so that the object's center of gravity is lowered, causing the object to lose its position.

One possible solution is to improve the gripping mechanism of the robot hand to increase the gripping force applied to the object. However, a robot hand with high gripping force consumes a lot of power. In addition, a high-output robot hand is heavy, which increases the load on each part of the articulated robot and the movement mechanism that moves the articulated robot, placing greater restrictions on the weight of objects that can be transported.

It is also possible to increase the number of fingers on the robot hand or equip the robot hand with a mechanism that changes the orientation of the finger tips in accordance with the shape of the object, but this would complicate the configuration of the robot hand. This would directly lead to increased manufacturing costs, operating costs, and maintenance costs for the robot hand, and would increase the failure rate of articulated robots, leading to a decrease in their operating rate.

The present invention was made in consideration of these problems, and aims to provide a robot hand that can grasp objects with curved or rough surfaces without complicating the structure of the articulated robot, and a pad for the robot hand that enables the robot hand to grasp an object.

According to one aspect of the present invention, there is provided a pad for a robot hand that is placed on the finger portion of a robot hand that grasps an object, the pad having a surface with a plurality of columnar blocks partitioned by intersecting grooves, each columnar block being formed from synthetic resin, having a flat upper surface, and having a hollow structure .

Preferably, a through hole is provided that penetrates from the front surface to the back surface, and the finger portion of the robot hand is fixed by a fixing member that is passed through the through hole.

More preferably, the top surface of the columnar block is rectangular, and the depth of the groove is greater than the length of each side of the top surface of the columnar block.

More preferably, the synthetic resin is polyurethane, nitrile rubber, hydrogenated nitrile rubber, or fluororubber. Also preferably, the filling rate of the hollow pillar block is 50% or more and 80% or less. More preferably, the base of the pillar block is rounded.

According to another aspect of the present invention, there is provided a robot hand for gripping an object, the robot hand comprising a plurality of fingers that contact the object and pinch and grip the object, and a finger movement mechanism that can move the fingers in directions to move closer to and farther away from each other, the fingers being provided with the above-mentioned robot hand pads.

A robot hand pad according to one embodiment of the present invention has a surface with multiple pillar blocks partitioned by lattice-like grooves, and each pillar block is made of synthetic resin and has a flat upper surface. Therefore, when an object is grasped by a robot hand having fingers on which this pad is arranged, each pillar block deforms to follow the shape of the object, and the upper surface of each pillar block deforms to follow the shape of the surface of the object. Therefore, the finger portions can contact the surface of the object over a wide area to hold the object, so the posture of the lifted object is adequately maintained.

Therefore, one aspect of the present invention provides a robot hand that can grasp an object having a curved or rough surface without complicating the structure of the articulated robot, and a pad for the robot hand that enables the robot hand to grasp an object.

FIG. 1 is a side view showing a schematic diagram of an articulated robot. FIG. 2 is a perspective view showing a schematic diagram of a tip portion of a robot hand. FIG. 2 is a perspective view showing a schematic diagram of a pad for a robot hand. Figure 4(A) is a cross-sectional view showing a schematic of how a pad for a robot hand according to an embodiment contacts an object, Figure 4(B) is a cross-sectional view showing a schematic of how a pad without grooves contacts an object, and Figure 4(C) is a cross-sectional view showing a schematic of how a pad with a non-flat upper end contacts an object.

An embodiment of the present invention will now be described with reference to the accompanying drawings. First, a robot hand in which a robot hand pad according to this embodiment is used will be described. The robot hand is a part attached to the tip of a multi-joint robot used, for example, for transporting and assembling items. Figure 1 is a side view showing a multi-joint robot (robot arm) 2.

The articulated robot 2 has a truncated cone-shaped base 4. The base 4 may be supported by a movement mechanism, and the articulated robot 2 may be moved horizontally by moving the base 4 with the movement mechanism. A cylindrical rotating member (rotating shaft) 6 is housed in the base 4, and the upper end side of the rotating member 6 is exposed from the base 4. The base 4 also houses a rotational drive source (not shown) such as a motor connected to the lower end side of the rotating member 6. The rotating member 6 is rotated by the rotational drive source around a rotational shaft that is roughly parallel to the vertical direction (up and down direction).

A rotation mechanism (joint mechanism) 8 is connected to the upper end of the rotating member 6, and one end of a columnar arm member (lower arm portion) 10 is connected to the rotation mechanism 8. The rotation mechanism 8 is equipped with a rotation drive source such as a motor, and rotates the arm member 10 around a rotation axis that is roughly parallel to the horizontal direction. Therefore, the arm member 10 can move forward and backward with the rotation mechanism 8 as a fulcrum.

A rotation mechanism (joint mechanism) 12 is connected to the other end of the arm member 10, and one end of a columnar arm member (upper arm) 14 is connected to the rotation mechanism 12. The rotation mechanism 12 is equipped with a rotation drive source such as a motor, and rotates the arm member 14 around a rotation axis roughly parallel to the horizontal direction, and also around a rotation axis roughly parallel to the length direction of the arm member 14. The rotation mechanism 12 causes the arm member 14 to rotate around the rotation mechanism 12 and spin on its own axis.

A rotation mechanism (joint mechanism) 16 is connected to the other end of the arm member 14, and one end of a columnar arm member (wrist portion) 18 is connected to the rotation mechanism 16. The rotation mechanism 16 is equipped with a rotation drive source such as a motor, and rotates the arm member 18 around a rotation axis roughly parallel to the horizontal direction, and also around a rotation axis roughly parallel to the length direction of the arm member 18. The rotation mechanism 16 causes the arm member 18 to rotate around the rotation mechanism 16 and spin on its own axis.

A connection member 20 is fixed to the other end of the arm member 18. A robot hand (gripper) 22 is attached to the connection member 20. The robot hand 22 has a number of fingers 28a, 28b and a finger movement mechanism 24 that moves the fingers 28a, 28b closer to each other.

For example, one end of rods 26a, 26b, a portion of which is housed in finger movement mechanism 24, is connected to the base end of each of fingers 28a, 28b. An air cylinder (not shown) is incorporated inside finger movement mechanism 24, and the other end of each of rods 26a, 26b is connected to a piston (not shown) of the air cylinder. Then, by operating finger movement mechanism 24 and moving the piston inside the air cylinder to move rods 26a, 26b, each of fingers 28a, 28b can be moved toward and away from each other.

An item to be transported is placed between the tips of the fingers 28a, 28b, and the finger movement mechanism 24 is operated to move the fingers 28a, 28b closer to each other. The tips of the fingers 28a, 28b then come into contact with the item, and the item is gripped between the fingers 28a, 28b. However, the mechanism of the finger movement mechanism 24 of the robot hand 22 is not limited to this, and the fingers 28a, 28b may be moved by other methods.

The articulated robot 2 is connected wirelessly or by wire to a control unit (not shown) that controls the operation of the articulated robot 2. For example, the control unit has a computer including a processor and memory, and generates control signals for controlling the operation of each component of the articulated robot 2 (the rotation drive source housed in the base 4, the rotation mechanisms 8, 12, 16, the robot hand 22, etc.). This controls each component, and the articulated robot 2 grasps an item with the robot hand 22 and moves the item.

The robot hand pads 30a, 30b according to this embodiment are fixed to the tips of the fingers 28a, 28b of the robot hand 22 when in use. The fingers 28a, 28b then come into contact with an object via the robot hand pads 30a, 30b, and exert a gripping force on the object. Conventionally, if the robot hand pads 30a, 30b according to this embodiment are not placed on the fingers 28a, 28b, depending on the shape, surface irregularities, and hardness of the object to be transported, the robot hand 22 may not be able to hold the object properly.

For example, when an object such as a hard, rough-surfaced casting with many curved surfaces is pinched and grasped between the flat fingers 28a, 28b, the contact area between the fingers 28a, 28b and the object may become extremely small. When the object is lifted in this state, the object rotates around the contact point so that the object's center of gravity becomes lower, and the object's posture changes. In particular, the heavier the object, the greater the force that rotates the object, so it is not easy to continue to grasp a heavy object with the robot hand 22 while maintaining the posture.

In order to increase the contact area between the fingers 28a, 28b and the object, it is possible to change the material of the fingers 28a, 28b themselves to a soft, easily deformed material. In this case, when the fingers 28a, 28b grip an object, the contact surfaces of the fingers 28a, 28b will deform to conform to the shape and rough surface of the object, increasing the contact area. However, if the fingers 28a, 28b themselves are soft, the fingers 28a, 28b will be deformed by the reaction force they receive from the object. As a result, they will be unable to exert a large gripping force on the object, which will cause the object to slip and fall off.

Therefore, it is preferable that the robot hand pads 30a, 30b according to this embodiment are attached to the tips of the finger portions 28a, 28b. FIG. 2 is a perspective view showing the tips of the finger portions 28a, 28b to which the robot hand pads 30a, 30b according to this embodiment are attached. FIG. 3 is a perspective view showing the robot hand pads 30, 30a, 30b according to this embodiment. The robot hand pads 30, 30a, 30b according to this embodiment will be described below.

The robot hand pad 30 according to this embodiment has a plurality of pillar blocks 34 on the surface 32a, which are partitioned by lattice-shaped grooves 38. Each pillar block 34 is made of synthetic resin, and has a flat upper surface 36. The robot hand pad 30 may have a flat base (not shown) that supports each pillar block 34. Alternatively, the entire pad may be made of the synthetic resin.

The robot hand pad 30 may have a through hole 40 that penetrates from the front surface 32a to the back surface 32b. In this case, the pad is fixed to the fingers 28a, 28b of the robot hand 22 by a fixing member 42 such as a bolt or screw that is passed through the through hole 40.

The robot hand pad 30 can be manufactured, for example, by a 3D printer using a synthetic resin material as ink. When forming the robot hand pad 30 with a 3D printer, it is not necessary to use ink material to fill the entire area of the columnar block 34, and the columnar block 34 may have a hollow structure. As will be described in detail later, if the columnar block 34 has a hollow structure, the columnar block 34 becomes more easily deformed, which may increase the gripping force of the robot hand 22 on an object.

The resin material may be provided so as to form the outer surface of the pillar block 34, and for example, it is preferable that the ratio (filling rate) of the area occupied by the resin material to the area occupied by the pillar block 34 is about 50%. If the filling rate of the pillar block 34 is significantly lower than 50%, the shape of the pillar block 34 will not be adequately maintained, and the robot hand 22 will not be able to apply sufficient gripping force to the item. On the other hand, if the filling rate is too high, the rigidity of the pillar block 34 will increase, making it difficult for the pillar block 34 to deform to follow the shape of the item. For example, it is preferable that the filling rate of the pillar block 34 is 50% or more and 80% or less.

However, the method of manufacturing the robot hand pads 30a, 30b is not limited to this. For example, the robot hand pad 30 may be manufactured by preparing a plate made of a synthetic resin material and forming a grid-like groove 38 on the surface of the plate using a tool with a saw blade.

Here, we will explain the function of the pillar block 34 and the groove 38 when the fingers 28a, 28b of the robot hand 22 grasp an article via the robot hand pad 30. Figure 4 (A) is a cross-sectional view showing an enlarged schematic view of the surface of the robot hand pads 30, 30a, 30b that come into contact with the article 1 to be transported by the articulated robot 2. However, for ease of explanation, Figure 4 (A) emphasizes the shape and deformation of the pillar block 34.

As shown in FIG. 4(A), when contacting the article 1, each columnar block 34 deforms to follow the shape of the article 1. More specifically, the article 1 held by the fingers 28a, 28b exerts a repulsive force on the columnar block 34 that contacts the article 1, causing the columnar block 34 to curve. As a result, even at the outer periphery of the contact area of the surface 1a of the article 1, the upper surface 36 of the columnar block 34 comes into contact with the article 1 over a wide area.

The deformation of the pillar blocks 34 is achieved by providing lattice-shaped grooves 38 on the surface 32a of the robot hand pad 30. In other words, when grooves 38 are formed between each pillar block 34, the space of the grooves 38 provides room for deformation and displacement of the pillar blocks 34. Therefore, compared to a case where the grooves 38 are not formed, the surface 32a of the robot hand pad 30 is more likely to deform to follow the surface 1a of the article 1.

Figure 4 (B) is a cross-sectional view that shows a schematic state in which a pad 44 without grooves 38 is brought into contact with the surface 1a of an article 1. As shown in Figure 4 (B), the surface 44a of the pad 44 without grooves 38 is continuous over a wide area without being divided. Therefore, when the pad 44 receives a repulsive force from the article 1 at the contact point with the article 1, the surface 44a deforms not only at this contact point but also on the outside thereof, and the surface 1a of the article 1 and the surface 44a of the pad 44 are separated on the outside. In other words, the contact area between the two is unlikely to increase.

As shown in FIG. 4(C), it is also possible to grasp the article 1 via a pad 46 having a number of pyramidal blocks 48 arranged on its surface, each of which has an uneven upper surface. In this case, groove-like spaces 50 are provided between each block 48, but when the article 1 is grasped via the pad 46, the contact area between the pad 46 and the article 1 does not increase significantly even if the blocks 48 are deformed.

Unlike the pad 44 shown in FIG. 4(B) and the pad 46 shown in FIG. 4(C), the pad 30 for a robot hand according to this embodiment shown in FIG. 3(A) is provided with multiple pillar blocks 34 and lattice-shaped grooves 38, and the top surface 36 of the pillar blocks 34 is flat. Therefore, when an item 1 is grasped via the pad 30 for a robot hand, the pillar blocks 34 deform, and the top surface 36 of the pillar blocks 34 comes into contact with the item 1 over a wide area.

The robot hand pad 30 is also suitable for use when the robot hand 22 grasps an object 1 that is wet and has water adhering to its surface 1a. The grooves 38 on the surface 32a of the robot hand pad 30 allow water adhering to the surface 1a of the object 1 to escape. Therefore, when the object 1 is grasped via the robot hand pad 30, no layer of water is formed between the two, making it difficult for the object 1 to slip against the robot hand pad 30.

Therefore, when the robot hand pad 30 according to this embodiment is disposed on the finger portions 28a and 28b, it becomes easier for the robot hand 22 to grasp any object 1. In addition, the posture of the grasped object 1 is also less likely to change.

In particular, as shown in FIG. 3 etc., when the top surface 36 of the columnar block 34 is rectangular or square and the depth of the groove 38 is greater than the length of each side of the top surface 36 of the columnar block 34, the columnar block 34 becomes more easily deformed. Therefore, the posture of the grasped article 1 is highly unlikely to change.

For example, it is preferable that the depth of the lattice-shaped groove 38 is greater than 1 time and less than 3 times the length of one side of the top surface 36 of one columnar block 34. It is even more preferable that the depth is 1.5 times to 2 times the length of one side of the top surface 36. For example, if the top surface 36 of one columnar block 34 is a square with sides of 4 mm, it is preferable that the depth of the groove 38 is about 7 mm and the width is about 1 mm. When the depth and width of the groove 38 are determined in this way, the columnar block 34 has sufficient flexibility and can exert a sufficient gripping force on the article 1.

The base of the pillar block 34 is preferably rounded as shown in FIG. 3 rather than squared, which is prone to stress concentration. The robot hand pad 30 according to this embodiment is designed to accommodate the pillar block 34, which is subject to daily deformation. Therefore, in order to increase the durability of the pillar block 34, it is preferable that the base of the pillar block 34 is rounded and that the pillar block 34 becomes thicker toward the base. In this case, the bottom of the groove 38 is rounded.

The synthetic resin used in the robot hand pad 30 according to this embodiment is preferably a material such as polyurethane, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), or fluororubber. If the synthetic resin used in the robot hand pad 30 is one of these materials, the columnar block 34 is easily elastically deformed and can exert a sufficient gripping force on the article 1.

As described above, when the robot hand pad 30 according to this embodiment is disposed on the fingers 28a, 28b of the robot hand 22 of the articulated robot 2, the robot hand 22 can adequately grasp even a heavy object 1 having a rough, curved surface. Furthermore, the object 1 is less likely to rotate while being transported by the articulated robot 2, making it easier to maintain its position.

In the above embodiment, the robot hand pad 30 is used with a robot hand 22 having two fingers 28a, 28b, but this aspect of the present invention is not limited to this. For example, the robot hand 22 may have three or more fingers, each of which may be provided with a robot hand pad 30.

In the above embodiment, the robot hand pads 30 are provided on all of the fingers 28a, 28b of the robot hand 22 of the articulated robot 2, but this is not a limitation of one aspect of the present invention. The robot hand pads 30 may be provided on only some of the fingers 28a, 28b of the robot hand 22.

Furthermore, in the above embodiment, the robot hand pad 30 is used in the robot hand 22 of an industrial articulated robot 2, but this aspect of the present invention is not limited to this. In other words, the robot hand pad 30 according to one aspect of the present invention may be used in other robot hands, or may be disposed and used in tools other than robot hands.

In the above embodiment, the robot hand pad 30 is partitioned by lattice-shaped grooves 38, and the upper surfaces 36 of the multiple pillar blocks 34 are rectangular or square. In other words, the pillar blocks 34 are rectangular, but one aspect of the present invention is not limited to this.

For example, the shape of the top surface 36 of the pillar block 34 may be a rectangle such as a rhombus, trapezoid, or parallelogram, and the pillar block 34 may be a quadrangular prism other than a rectangular parallelepiped. In addition, the top surface 36 of the pillar block 34 may be a polygonal shape such as a hexagon or octagon, and the pillar block 34 may be a polygonal prism such as a hexagonal prism or octagonal prism.

Furthermore, the multiple pillar blocks 34 provided on the robot hand pad 30 do not all have to be the same size and shape. The robot hand pad 30 may be provided with multiple types of pillar blocks 34 whose upper surfaces 36 are different in size and shape. In addition, the groove 38 does not have to be continuous from one end of the robot hand pad 30 to the other end.

The structures, methods, etc., according to the above embodiments can be modified as appropriate without departing from the scope of the present invention.

1 Item 1a Surface 2 Articulated robot (robot arm)
4 Base 6 Rotating member (rotating shaft)
8 Rotation mechanism (joint mechanism)
10 Arm member (lower arm)
12 Rotation mechanism (joint mechanism)
14 Arm member (upper arm)
16 Rotation mechanism (joint mechanism)
18 Arm member (wrist portion)
20 Connection member 22 Robot hand 24 Finger movement mechanism 26a, 26b Rod 28a, 28b Finger 30, 30a, 30b Pad for robot hand 32a Surface 32b Back surface 34 Pillar-shaped block 36 Top surface 38 Groove 40 Through hole 42 Fixing member 44 Pad 44a Surface 46 Pad 48 Block 50 Space

Claims (7)

A pad for a robot hand that is provided on a finger portion of a robot hand that grasps an object,
The plate has a surface having a plurality of pillar-shaped blocks partitioned by grooves intersecting each other,
A pad for a robot hand, characterized in that each columnar block is made of synthetic resin, has a flat upper surface, and is hollow. A through hole is provided penetrating from the front surface to the back surface,
2. The pad for a robot hand according to claim 1, wherein the pad is fixed to the finger portion of the robot hand by a fixing member passed through the through hole. The top surface of the pillar block is rectangular,
3. The pad for a robot hand according to claim 1, wherein the depth of the groove is greater than the length of each side of the upper surface of the pillar-shaped block. A pad for a robot hand according to any one of claims 1 to 3, characterized in that the synthetic resin is polyurethane, nitrile rubber, hydrogenated nitrile rubber, or fluororubber. 5. The pad for a robot hand according to claim 1, wherein the filling rate of the hollow pillar blocks is 50% or more and 80% or less. 6. The pad for a robot hand according to claim 1, wherein the base of the pillar-shaped block is rounded. A robot hand that grasps an object,
a plurality of finger portions that come into contact with the article to pinch and grip the article; and a finger portion moving mechanism that can move each of the finger portions in a direction to move closer to and away from each other,
A robot hand, comprising a pad for a robot hand according to any one of claims 1 to 6 disposed on the finger portion.

Images