Robot hand

Abstract

We offer a versatile robotic hand capable of skillfully gripping a wide variety of workpieces. [Solution] A robot hand comprising a gripping means for grasping a workpiece and a suction means for adsorbing the workpiece, wherein the gripping means has a plurality of fingers extending from the hand body of the robot hand, the base end of each of the plurality of fingers is rotatably attached to the hand body, and the spacing between the fingertips of the plurality of fingers is adjustable, and the suction means is housed within the hand body and has a suction portion that moves forward and backward relative to the hand body.

Description

Technical Field

[0001] The present invention relates to a robot hand.

Background Art

[0002] In recent years, general-purpose robots that perform operations such as grasping, lifting, transporting, and supporting objects have been used in various fields such as manufacturing and logistics. In particular, regarding the robot hand that bears the part of the robot that mimics the function of the palm beyond the human wrist among the parts of the robot, various proposals have been made.

[0003] For example, Patent Document 1 proposes a robot hand that curves a finger member by a fluid pressure actuator that extends in one direction and curves in a direction different from this one direction. According to this robot hand, when handling easily deformable articles (hereinafter also referred to as workpieces) such as food and pharmaceuticals or delicate workpieces, it becomes possible to handle the workpiece through a flexible gripping force like that of a human hand.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent logistics operations, which handle a wide variety of workpieces with different shapes and sizes, applying robot hands requires the ability to reliably grasp these diverse workpieces. In this regard, the robot hand described in Patent Document 1 is effective for a wide variety of workpieces and has the advantage of enabling smooth picking operations, particularly by utilizing a fluid pressure actuator. On the other hand, even with the above-mentioned robot hand, there is a possibility of failing to grasp workpieces that are thin or short in height, so there is a need to enable the handling of such workpieces. Furthermore, when picking workpieces from a case containing many workpieces, it becomes difficult to reliably grasp workpieces in narrow spaces where the fingers of the robot hand can be inserted, such as the four corners of the case, and improvements in this area have also been requested.

[0006] As described above, robot hands using fluid pressure actuators can handle a wide variety of workpieces, but there is a need for a robot hand that can handle workpieces of even more shapes and sizes. In other words, the present invention aims to provide a versatile robot hand that can skillfully grasp a wide variety of workpieces. [Means for solving the problem]

[0007] The inventors diligently studied the structure of a robot hand that could accommodate a wider range of shapes and sizes of workpieces, and discovered that a workpiece holding mechanism using suction is effective for low-height workpieces, as described above. Therefore, they investigated the problems that arise when equipping a robot hand using a fluid pressure actuator with a suction-based holding mechanism, and ultimately discovered a new finger structure for the robot hand. The present invention is derived from these findings, and its gist is as follows.

[0008] 1. A robot hand comprising a gripping means for grasping a workpiece and a suction means for adsorbing the workpiece, The gripping means has a plurality of fingers extending from the hand body of the robot hand, the base end of each of the plurality of fingers is rotatably attached to the hand body, and the spacing between the fingertips of the plurality of fingers is adjustable. The suction means is housed within the hand body and has a suction portion that moves back and forth relative to the hand body. Robot hand.

[0009] 2. The robot hand according to claim 1, wherein the fingers have a rotation angle α of 90° or more, starting from the position where the distance between them is narrowest, and moving toward the hand body.

[0010] 3. The robot hand according to claim 1 or 2, wherein the fingers are fluid pressure actuators that extend in one axis direction and curve in a direction different from that axis direction. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a robot hand that can utilize both a gripping mechanism with fingers and a suction mechanism in cooperation. In particular, since the fingers can rotate around their base ends relative to the hand body, the fingers can be moved away from the path and surrounding area of ​​the suction mechanism that extends from the hand body to reach the workpiece, thus allowing the suction mechanism to be preferentially applied to the workpiece. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows an example of a robotic hand and a robotic arm to which the robotic hand is attached according to the present invention. [Figure 2] This figure shows the rotation of the fingers in the robot hand of the present invention. [Figure 3] This diagram shows the operation of a finger as a fluid actuator. [Figure 4] This figure illustrates the effect of rotating the fingers in the robot hand of the present invention. [Figure 5]This figure illustrates the cooperative mechanism of the gripping means and suction means in the robot hand of the present invention. [Figure 6] This is a schematic diagram showing the rotation mechanism for rotating the finger. [Figure 7] This is a schematic diagram showing the mechanism for transmitting the driving force to rotate the fingers. [Modes for carrying out the invention]

[0013] The robot hand of the present invention is used by being attached to the tip of a robot arm. The structure of this robot arm is not particularly limited, but for example, the robot arm 1 shown in Figure 1 can be used. This robot arm 1 will be described below with reference to Figure 1.

[0014] <Robot Arm 1> Figure 1 is a perspective view of a robot arm 1 having a robot hand 2 according to the present invention. As shown in Figure 1, the robot arm 1 has a base 11 attached to a foundation (not shown), an arm 13a extending from the base 11 via a joint 12a, and an arm 13b extending from the arm 13a via a joint 12b. Thus, the robot hand 2 is attached to the tip of the connected arm 13b via a joint 12c. Next, the robot hand 2 according to the present invention will be described in detail with reference to the drawings.

[0015] <Robot Hand 2> As shown in Fig. 1, the robot hand 2 has a gripping means 3 for gripping a workpiece (not shown) and a suction means 4 for sucking the workpiece. As shown in the perspective view from the tip side of the robot hand 2 in Fig. 2, the gripping means 3 is composed of a plurality of, in the illustrated example, four fingers 30a to 30d that are rotatably attached to the hand body 20. That is, the bases of the fingers 30a to 30d are respectively attached at four equally spaced positions on the circumference of the end of the cylindrical hand body 20 in the illustrated example, and they are rod-shaped bodies extending in a uniaxial direction from this base toward the tip. Each of the fingers 30a to 30d in the present embodiment is a fluid pressure actuator that can perform an operation of curving from the state of extending in the uniaxial direction shown in Fig. 2 toward a direction different from the uniaxial direction as shown in Fig. 3. For the fluid pressure actuator, for example, a "rubber actuator" composed of a rubber tube and a sleeve of high-strength fibers surrounding it can be used. That is, by introducing the working fluid into the rubber tube from the inlet 31, an operation of curving toward the tip as shown by the two-dot chain line in Fig. 3 can be given. By such an operation, it is possible to strongly grip the workpiece to be gripped, or conversely, to softly grip using the finger tips. The working fluid is appropriately determined according to the types of the workpiece and the fluid pressure actuator, and as an example, compressed air is used.

[0016] As described above, since each of the fingers 30a to 30d of the gripping means 3 is rotatable with respect to the hand body 20, for example, from the position P1 (rising point) closest to the side surface of the hand body 20 shown in Fig. 2(b) to the position P2 (descending point) where the fingers 30a to 30d contact each other toward the central axis of the hand body 20 in the direction in which the mutual distance between the fingers 30a to 30d shown in Fig. 2(a) becomes narrower, the fingers 30a to 30d can operate. Therefore, in this operating range, the workpiece can be easily pinched. Furthermore, at the same time as pinching the workpiece with the fingers 30a to 30d, or after pinching it, by giving the bending operation by the above-described fluid pressure actuator, the gripping can be made stronger, or the workpiece can be softly gripped using the finger tips, or the fingers can be given movements corresponding to the workpiece.

[0017] Here, the rotation and bending operations of the fingers 30a to 30d may be synchronized with each other or independently controlled for each finger. Also, the rotation range of the fingers 30a to 30d and the angle α from the above-described rising point P1 to the falling point P2 need to be 90° or more from the falling point side. In particular, it is preferable that the angle α is such that the fingers 30a to 30d can rotate at an angle of 90° or more with respect to the central axis of the hand body 20. On the other hand, the upper limit of the angle α may be 180°, but it is about 135° due to the constraints of the equipment configuration.

[0018] Also, as shown in Fig. 2(a), the suction means 4 is housed and installed in the hand body 20, and as shown in Fig. 2(b), it is a tubular body that moves forward and backward in the axial direction of the hand body 20, and for example, vacuum suction can be utilized. For example, in the illustrated example, the suction means 4 has a cylindrical suction portion 40 that abuts on the work, a pipe 41 for evacuating the inside of the cylinder of the suction portion 40, and a rack 42 for moving the suction portion 40 forward and backward with respect to the hand body 20. The suction portion 40 is taken in and out of the hand body 20 by reciprocating the rack 42 via a pinion (not shown) on the hand body 20 side.

[0019] That is, the suction means 4 extends the suction portion 40 from the hand body 20 toward the work to reach the work, evacuates it, and sucks the work onto the suction portion 40 to hold the work. When operating this suction means 4, as shown in Fig. 2(b), it is necessary to rotate the fingers 30a to 30d to the rising point side at an angle α of 90° or more.

[0020] For example, when picking a workpiece W stored in the case 50 shown in Figure 4(a), if the side wall of the case 50 obstructs the insertion of fingers 30a to 30d into the case 50, it is necessary to hold and transport the workpiece W using the suction means 4. In this case, as described above, it is necessary to rotate the fingers 30a to 30d toward the lifting point at an angle α: 90° or more so that they do not come into contact with the side wall of the case 50. That is, as shown in Figure 4(b), by retracting the fingers 30a to 30d to a position where they do not come into contact with the side wall of the case 50, it becomes possible to lower the hand body 20 to within reach of the suction means 4 and to lower the suction means 4 to the workpiece W.

[0021] Furthermore, after the workpiece W is held by the suction means 4, as shown in Figure 5, by rotating fingers 30a to 30d toward the lowering point and gripping the workpiece W with fingers 30a to 30d, the workpiece W is firmly held vertically by suction and firmly held horizontally by gripping with the fingers, thereby enabling high-speed transport that was not possible with conventional suction transport.

[0022] The rotation mechanism for the fingers 30a to 30d in the gripping means 3 is not particularly limited and can be any mechanism that can provide the fingers with the rotational motion described above. However, preferred examples of this rotation mechanism will be explained with reference to Figures 6 and 7. Figures 6 and 7 show the rotation mechanism for attaching the fingers 30a to 30d in the hand body 20, and Figure 7 shows the transmission mechanism that provides power to the rotation mechanism.

[0023] As shown in Figures 6 and 7, the hand body 20 has four rotating shafts 31 arranged to form the four sides of a rectangle. Each of the fingers 30a to 30d is fixedly attached to each rotating shaft 31.

[0024] Here, as shown in Figure 6, the interrelationship of the four rotating shafts 31 is such that two of the four rotating shafts 31 have bevel gears 32 at both ends of the shaft and the remaining two have bevel gears 32 at one end of the shaft, and these bevel gears 32 are engaged with each other. In other words, the four rotating shafts 31 are connected at three points where the bevel gears 32 engage with each other, and as a result, the four rotating shafts 31 can be rotated synchronously. Note that the other ends of the two rotating shafts 31 that have bevel gears 32 at only one end of the shaft only need to be rotatably fixed to the base 21.

[0025] Next, the transmission mechanism for rotating the four rotating shafts 31 will be explained using the schematic diagram shown in Figure 7. Specifically, a worm wheel 22a is formed on the other end of one of the two rotating shafts 31a of the four rotating shafts 31, each of which has a bevel gear 32 on only one end. A worm 22b is formed on the drive shaft of the drive source 21 built into the hand body 20, and by engaging the two, rotational drive is transmitted to the rotating shafts 31a at a right angle. The rotational force transmitted to the rotating shafts 31a is also transmitted to the three rotating shafts 31 via the three points where the bevel gears 32 engage with each other, as described above.

[0026] Furthermore, the base ends of the fingers 30a to 30d are fixed to the intermediate part of each of the four synchronously rotating shafts 31, resulting in the fingers 30a to 30d being attached to the hand body 20 so as to be rotatable together with the rotating shafts 31. In other words, by controlling the driving force from the drive source 21, the rotation angle α of the fingers 30a to 30d that rotate together with the rotating shafts 31 can be changed.

[0027] The mechanism described above, which rotates the fingers 30a to 30d, allows the distance between the fingers 30a to 30d to be changed according to the size of the workpiece to be gripped. After the workpiece is placed between the fingers 30a to 30d, the fingers (fluid pressure actuators) are introduced to bend, thereby securely gripping the workpiece. At this time, the force with which the fingertips push the workpiece is received as a reaction force (rotational torque) at the base of the fingers. In a normal transmission mechanism, this reaction force is transmitted to the drive source (motor), so it is necessary to maintain this state by controlling the motor's drive force or to intervene in some kind of locking mechanism.

[0028] On the other hand, the transmission mechanism using the worm and worm wheel shown in Figure 7 theoretically transmits power from the driving side to the driven side, but does not transmit power from the driven side to the driving side (a so-called self-locking function). By using this function, the transmission mechanism can lock rotation against the torque generated when the finger (fluid pressure actuator) grips. In other words, it is a transmission mechanism that is particularly advantageous when the finger is a fluid pressure actuator. Furthermore, by adopting such a transmission mechanism, the motor can be made to have the capacity necessary to rotate the finger, thus contributing to the miniaturization and weight reduction of the motor. [Explanation of Symbols]

[0029] 1. Robot arm 2. Robot Hand 3 Gripping means 4 Adsorption means 11 Bass 12a~12c Joints 13a~13c Arm 20 Handheld Body 21 Power source 22a Worm Wheel 22b Warm 30a~30d fingers 31 Rotation axis 31a Rotation axis 32 Bevel gears 50 cases Double job

Claims

1. A robot hand comprising a gripping means for grasping a workpiece and a suction means for adsorbing the workpiece, The gripping means has a plurality of fingers extending from the hand body of the robot hand, the base end of each of the plurality of fingers is rotatably attached to the hand body, and the spacing between the fingertips of the plurality of fingers is adjustable. The suction means is housed within the hand body and has a suction portion that moves back and forth relative to the hand body. Robot hand.

2. The robot hand according to claim 1, wherein the fingers have a rotation angle α of 90° or more, starting from the position where the distance between them is narrowest, and moving toward the hand body.

3. The robot hand according to claim 1 or 2, wherein the fingers are fluid pressure actuators that extend in one axis direction and curve in a direction different from that axis direction.

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