Robot hand, control method for robot hand and control program for robot hand

Abstract

To provide a robot hand achieving both easiness of control and simplification of structure.SOLUTION: A robot hand includes: a circular member rotated by an actuator around a central axis; a support member rotatably supporting the circular member; three or more finger members each of which is born by an outer peripheral part of the circular member at a base end part, extends from the base end part to an end part, and curves or bends to the circular member side at least at the end part; and a link mechanism which displaces each finger member with respect to the circular member between a falling-down state and a vertically erect state when the circular member is rotated with respect to the support member.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a robot hand, a control method for a robot hand, and a control program for a robot hand. [Background technology]

[0002] Various robot hands that can be attached to the end of a robot arm have been developed. Specific examples of robot hands include hands that resemble human hands as much as possible, parallel grippers that omit joints, and soft grippers that operate movable parts using fluids (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2024-121657 A Summary of the Invention [Problem to be solved by the invention]

[0004] When trying to make a robot hand resemble a human hand, the number of joints increases, making it difficult to control. If it is simplified like a parallel gripper, it cannot grasp an object unless certain conditions are met. When using fluids like a soft gripper, structural constraints become greater. In other words, all of the robot hands developed so far have their pros and cons, and it has been difficult to achieve both ease of control and simplified structure at the same time.

[0005] The present invention has been made to solve such problems, and provides a robot hand etc. that achieves both ease of control and simple structure. [Means for solving the problem]

[0006] A robot hand in a first aspect of the present invention comprises a circular member that is rotated around a central axis by an actuator, a support member that rotatably supports the circular member, three or more finger members, each of which is journalled at its base end on the outer periphery of the circular member, extends from the base end to a tip end and is curved or bent towards the circular member at at least its tip end, and a link mechanism that displaces each finger member between a horizontal position and an upright position relative to the circular member when the circular member is rotated relative to the support member.

[0007] A control method for a robot hand in a second aspect of the present invention is a control method for a robot hand having a circular member that is rotated around a central axis by an actuator, a support member that rotatably supports the circular member, and a plurality of finger members that are displaced from a horizontal state to a vertical state relative to the circular member when the circular member is rotated relative to the support member, the control method including a displacement step of displacing the plurality of finger members to a horizontal state, an approach step of bringing the robot hand closer to an object to be held based on a recessed portion of the object to be held or a grounding portion of the object to be held, a accommodating step of accommodating at least a portion of the object to be held in a holding space surrounded by the plurality of finger members and the circular member by inserting the tip portions of each of the plurality of finger members into the recessed portion or the grounding portion during the process of displacing the plurality of finger members to the vertical state, and a maintaining step of maintaining the holding space without displacing the plurality of finger members while the object to be held is moved.

[0008] A control program for a robot hand in a third aspect of the present invention is a control program for a robot hand including a circular member that is rotated around a central axis by an actuator, a support member that rotatably supports the circular member, and a plurality of finger members that are displaced from a horizontal state to a vertical state relative to the circular member when the circular member is rotated relative to the support member, the control program including a displacement step of displacing the plurality of finger members to a horizontal state, and an approach step of approaching the robot hand to an object to be held based on a recessed portion of the object to be held or a grounded portion of the object to be held;

[0009] In the process of displacing the multiple finger members to a vertical position, the computer executes a storing step of storing at least a portion of the object to be held in a holding space surrounded by the multiple finger members and the circular member by inserting the tip portions of each of the multiple finger members into recessed portions or grounded portions, and a maintaining step of maintaining the holding space without displacing the multiple finger members while the object to be held is moved. Effect of the Invention

[0010] The present invention makes it possible to provide a robot hand etc. that is both easy to control and has a simple structure. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing the vicinity of the tip of a robot arm to which a robot hand according to this embodiment is attached. FIG. [Diagram 2] 1A to 1C are diagrams illustrating the structure and operation of a robot hand. [Diagram 3] FIG. 2 is an exploded perspective view of a link mechanism and its surrounding parts. [Figure 4] FIG. 13 is a diagram showing the robot hand gripping a plastic bottle. [Diagram 5] 1A to 1C are diagrams showing a procedure for gripping a plastic bottle. [Figure 6] FIG. 13 is a diagram showing a state in which the robot hand grips the cap of a plastic bottle. [Figure 7] FIG. 1 is a system configuration diagram of a gripping device including a robot hand. [Figure 8] FIG. 13 is a diagram showing a gripping flow by a robot hand. [Figure 9] 13A to 13C are diagrams illustrating the operation of a robot hand that employs a link mechanism of a different type. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Specific embodiments will be described through the following disclosure, but the claimed invention is not limited to the following embodiments. In addition, not all of the configurations described in the embodiments are necessarily essential as means for solving the problem. In addition, in each figure, those with the same reference numerals have the same or similar configurations. In addition, in each figure, when there are multiple structures with the same or similar configurations, in order to avoid complication, some may be referenced and the same reference numerals may not be referenced to the others.

[0013] 1 is a diagram showing the vicinity of the tip of a robot arm 200 to which a robot hand 100 according to this embodiment is attached. The robot hand 100 is used by being attached to a hand base 210 provided at the tip of the robot arm 200. A hand actuator 220 for driving the robot hand 100 is provided inside the hand base 210.

[0014] The robot hand 100 mainly comprises a circular member 110 that is rotated around a central axis by a hand actuator 220, a support member 120 that rotatably supports the circular member 110, six finger members 130 that operate in conjunction with each other to grasp an object, and a link mechanism 140 that displaces each finger member 130 between a horizontal position and an upright position relative to the circular member 110 when the circular member 110 is rotated relative to the support member 120.

[0015] Support member 120 has a substantially cylindrical shape and is fixed to hand pedestal 210. Circular member 110 has a substantially cylindrical shape and its center is connected to the output shaft of hand actuator 220, and rotates around the output shaft of hand actuator 220 as a central axis. As will be described in detail later, the range in which circular member 110 rotates is approximately 30° around the central axis.

[0016] Fig. 2 is a diagram for explaining the structure and operation of the robot hand 100. In particular, Fig. 2(A) shows a horizontally laid state in which the finger members 130 are laid on their sides relative to the circular member 110, Fig. 2(C) shows a vertically stood state in which the finger members 130 are stood upright relative to the circular member 110, and Fig. 2(B) shows a displacement state intermediate between the horizontally laid state and the vertically stood state. In addition, the upper figures in each figure show a front view of the robot hand 100, and the lower figures show a bottom view.

[0017] First, a description will be given with reference to Fig. 2(B). The support member 120 functions as a fixed part fixed to the hand base 210. The circular member 110 is supported so as to be rotatable by a part of its peripheral side surface being nested in the support member 120, and receives a driving force from the hand actuator 220 to rotate about a central axis P c The circular member 110 may also be called a sliding portion because it slides relative to the support member 120.

[0018] The finger members 130 are each supported at their base end 130a on the outer periphery 110a of the circular member 110, and extend while curving from the base end 130a to the tip end 130b. In this embodiment, six finger members 130 are provided, but at least three finger members 130 may be provided as blades for gripping an object.

[0019] When the circular member 110 is rotated rightward (clockwise) in bottom view relative to the support member 120, the link mechanism 140 causes each of the finger members 130 to stand up relative to the circular member 110. Conversely, when the circular member 110 is rotated leftward (counterclockwise) in bottom view relative to the support member 120, each of the finger members 130 is caused to lie down relative to the circular member 110.

[0020] FIG. 2(A) shows a state in which the circular member 110 is rotated counterclockwise to the limit of its rotation range. When the circular member 110 is rotated counterclockwise to the limit of its rotation range, all the finger members 130 are in a horizontally lying state with respect to the circular member 110. Since the finger members 130 are curved from the base end 130a to the tip end 130b as described above, in the horizontally lying state, each finger member 130 is arranged so as to follow the outer periphery 110a of the circular member 110. In addition, in this embodiment, in the horizontally lying state, the tip end 130b of each finger member 130 is in a relationship in which it overlaps with the base end 130a of the finger member 130 adjacent to one side. In a bottom view, the tip end 130b of the finger member 130 overlaps with the base end 130a of the finger member 130 adjacent to one side in the radial direction of the circular member 110. In this way, by determining the curvature and length of the finger members 130 so that they overlap, it is possible to achieve both compactness in the lying position and sufficient finger length to grasp various objects.

[0021] 2(C) shows the state where the circular member 110 has been rotated clockwise to the limit of its rotation range. When the circular member 110 has been rotated clockwise to the limit of its rotation range, all of the finger members 130 are in a vertically standing state upright relative to the circular member 110. In this embodiment, the central axis P of the circular member 110 when the circular member 110 is displaced from the sideways state shown in FIG. 2(A) to the vertically standing state shown in FIG. 2(C) is c The rotation angle around the circumference is assumed to be approximately 30°.

[0022] In the upright position, the tips 130b of the six finger members 130 are aligned along the central axis P. c By gathering the tips 130b of the finger members 130 together in this manner, it is possible to prevent the object to be grasped from being lost or dropped when being lifted up.

[0023] In the process of changing from a lying state to a standing state, the six finger members 130 gradually rise up in accordance with the rotation angle with respect to the circular member 110, and a holding space W is formed between each of the curved finger members 130 and the circular member 130. The robot hand 100 grasps the object to be grasped by storing at least a part of the object to be grasped in the holding space W. A specific example will be described in detail later.

[0024] Since each finger member 130 is curved as described above, in the upright position, it is curved toward the circular member 110 with respect to the vertical line V defined near the outer periphery of the circular member 110, as shown in the upper diagram of Fig. 2(C). In this embodiment, the finger members 130 are formed as curved blades, but the finger members 130 may be formed as bent blades as long as the tip ends are inclined toward the circular member 110. In this case as well, in the horizontal position, it is preferable that the tip end of each finger member overlaps the base end of the finger member adjacent to one side.

[0025] 3 is an exploded perspective view of the link mechanism 140 and its surroundings. As described above, the finger member 130 is pivotally supported at its base end 130a on the outer periphery 110a of the circular member 110. Specifically, as shown in the figure, one end of the pivot shaft 112 is inserted and fixed into a shaft fitting hole 111 provided on the outer periphery 110a of the circular member 110. A bearing 113 is fitted on the inner periphery side of the other end of the pivot shaft 112, and its outer periphery side is fitted into a fitting hole 131 provided on the base end 130a of the finger member 130. The finger member 130 can swing around the pivot shaft 112 by being pivotally supported on the outer periphery 110a of the circular member 110 in this manner.

[0026] The link mechanism 140 is mainly composed of a support side ball joint 141, a rotation side ball joint 142, a joint shaft 143, a support side joint base 144, and a rotation side joint base 145. The support side ball joint 141 and the rotation side ball joint 142 have their inner rings connected to each other by the joint shaft 143.

[0027] The support side ball joint 141 is a first ball joint provided on the support member 120 side. The rotation side ball joint 142 is a second ball joint provided on the finger member 130 side. An outer ring of the support side ball joint 141 is fixed to a support side joint seat 144, and the support side joint seat 144 is attached and fixed to a seat mounting part 122 provided on the outer circumferential part 120a of the support member 120. An outer ring of the rotation side ball joint 142 is fixed to a rotation side joint seat 145, and the rotation side joint seat 145 is attached and fixed to a seat mounting part 132 provided on the base end part 130a of the finger member 130. By providing the link mechanism 140 in this manner, when the circular member 110 is rotated relative to the support member 120, the finger member 130 can be displaced between a lying state and a standing state as described with reference to FIG. 2.

[0028] 4 is a diagram showing how the robot hand 100 grasps a plastic bottle 910. The plastic bottle 910 is composed of a bottle body 911 and a cap 912 that closes the drinking spout of the bottle body 911, and the robot hand 100 attempts to grasp the plastic bottle 910 by inserting the tip 130b of the finger member 130 into a recess 911a formed between the cap 912 and the bottle body 911.

[0029] 5 is a diagram showing a procedure for gripping a plastic bottle 910. Starting from the left, the process is shown up to the point where the finger members 130 in a horizontal position wrap around the cap 912.

[0030] First, the robot hand 100 is driven by the robot arm 200 to be positioned directly above the cap 912. Specifically, the robot hand 100 is positioned away from the cap 912 so that the tip portion 130b of the finger member 130 can be inserted into the recessed portion 911a recognized by image recognition, for example. At this time, the robot hand 100 is in a lying state.

[0031] From this state, the circular member 110 is gradually rotated to raise the finger members 130. Then, as described above, a holding space W is formed between the finger members 130 and the circular member 110, and the cap 912 is housed in this holding space W so as to be enveloped therein.

[0032] Once cap 912, which constitutes a part of plastic bottle 910, which is the object to be grasped, is accommodated in holding space W, rotation of circular member 110 is stopped and a static torque is applied to hand actuator 220 so as to maintain the rotation angle, thereby maintaining holding space W. Thereafter, plastic bottle 910 is lifted by the drive of robot arm 200 and moved to the target position.

[0033] 4 and 5, tip portions 130b of finger members 130 are inserted into a recess in the object to be grasped and part of the object to be grasped is accommodated in holding space W, but if there is no recess in the object to be grasped, or if there is a recess but it is too shallow to insert tip portions 130b of finger members 130, another grasping method is attempted. Figure 6 is a diagram for explaining such a method, and shows how robot hand 100 grasps cap 912 of plastic bottle 910.

[0034] The cap 912 is placed directly on the ground surface 921, and there is no particular recess. In such a case, the finger members 130 are inserted into the grounding portion 921a where the grounding surface 921 and the cap 912 come into contact. If the cap 912, which is the object to be grasped, is of a size that can be accommodated in the holding space W and the finger members 130 are successfully inserted into the grounding portion 921a, the cap 912 is accommodated in the holding space W with the finger members 130 standing upright, and is lifted up and moved to the target position.

[0035] Next, a system configuration of a gripping device including the robot hand 100 will be described. Fig. 7 is a system configuration diagram of a gripping device including the robot hand 100. The gripping device mainly includes a CPU (Central Processing Unit) 300, a memory 310, a communication interface 320, a graphic board 330, a hand actuator 220, a hand sensor 221, an arm actuator 230, an arm sensor 231, and a camera unit 240. The CPU 300 is a processor that controls the gripping device and executes programs. The CPU 300 reads out a control program stored in the memory 310 and executes various processes related to gripping an object to be gripped.

[0036] The memory 310 is a non-volatile storage medium, and is configured, for example, by a flash memory. The memory 310 stores various parameters and the like in addition to programs for controlling and processing the gripping device. The communication interface 320 includes, for example, a LAN (Local Area Network), and is connected to a computer in the robot body to mediate the exchange of instructions and information. The graphics board 330 is an arithmetic processing board that performs specific image processing at high speed, and for example extracts a specific subject image from a given image and returns the extraction result to the CPU 300.

[0037] As described above, the hand actuator 220 is an actuator that rotates the circular member 110 of the robot hand 100. The hand sensor 221 is a sensor attached to the robot hand 100, such as a slip sensor attached to the tip 130b of the finger member 130. The arm actuator 230 is an actuator that drives the robot arm 200. The arm sensor 231 is a sensor attached to the robot arm 200, such as a rotary encoder that detects the rotation angle of a joint. The camera unit 240 includes a camera that captures an image of the environment around the gripping device, and transmits the captured image to the CPU 300.

[0038] The CPU 300 also serves as a functional calculation unit that executes various calculations in response to processing instructed by a control program for the robot hand. The CPU 300 can function, in particular, as a finger control unit 301, an arm control unit 302, and an object recognition unit 303. The finger control unit 301 controls the operation of the finger members 130 by controlling the driving of the hand actuator 220. Specifically, it executes control of a displacement step of displacing the finger members 130 to a sideways state, a storage step of inserting the tip portion 130b into a recessed portion or a grounded portion to store at least a part of the object to be grasped in the holding space W, and a maintenance step of maintaining the holding space W without displacing the finger members 130 during the period in which the object to be grasped is moved.

[0039] The arm control unit 302 controls the operation of the robot arm 200 by controlling the arm actuator 230. Specifically, it executes control of an approach step for bringing the robot hand 100 closer to the object to be grasped based on the recessed parts and grounding parts of the object to be grasped. The object recognition unit 303 receives environmental image data from the camera unit 240, and executes image processing on the graphic board 330 to execute control of an environmental recognition step for calculating position information of the recessed parts and grounding parts of the object to be grasped.

[0040] Next, a process flow of the process in which the robot hand 100 grasps an object to be grasped and moves it to a target position will be described. Fig. 8 is a diagram showing a grasping flow by the robot hand 100. The flow starts when the designation of the object to be grasped and the movement target position is accepted.

[0041] In step S101, the object recognition unit 303 recognizes where the specified object to be grasped is located in the environment, and further recognizes the position of a recess or a grounded portion of the object to be grasped into which the tip portion 130b of the finger member 130 can be inserted. In step S102, the finger control unit 301 displaces the finger member 130 to a sideways state (displacement step). Note that steps S101 and S102 may be executed in reverse order or in parallel.

[0042] In step S103, the arm control unit 302 causes the robot hand 100 to approach the object to be grasped based on the position of the recessed portion or the grounded portion recognized in step S101 (approach step). Note that since the robot hand 100 holds at least a part of the object to be grasped in the holding space W as described above, the object to be grasped may also be referred to as a held object.

[0043] In step S104, finger control unit 301 gradually changes finger members 130 from a horizontally laid state to a vertically standing state, and inserts tip portions 130b of finger members 130 into recessed portions or grounded portions, thereby storing at least a portion of the object to be grasped in holding space W (storing step). Note that, for example, as described with reference to FIG. 5, in the case where tip portions 130b of finger members 130 are hooked into recessed portions, the storing step is completed before finger members 130 reach the vertically standing state.

[0044] In step S105, the finger control unit 301 maintains the holding space W without displacing the finger members 130 until the arm control unit 302 drives the robot arm 200 to make the object to be grasped reach the target position (maintenance step). When the object to be grasped has been moved to the target position, the finger control unit 301 returns the finger members 130 to the lying state, and ends the series of processes.

[0045] In the above-described embodiment, a mechanism using a ball joint is adopted as the link mechanism 140, but the link mechanism 140 is not limited to this. FIG. 9 is a diagram for explaining the operation of a robot hand 100′ adopting a link mechanism of another form. In particular, FIG. 9(A) is a front view that shows a schematic representation of only one finger member 130 in a lateral state in which the finger members 130 are laid on their sides relative to the circular member 110, FIG. 9(C) is a front view that shows a schematic representation of only one finger member 130 in a vertical state in which the finger members 130 are erected upright relative to the circular member 110, and FIG. 9(B) is a front view that shows a schematic representation of a displacement state intermediate between the lateral state of FIG. 9(A) and the vertical state of FIG. 9(C).

[0046] The robot hand 100' employs a cam mechanism as the link mechanism 140'. Specifically, the link mechanism 140' is composed of a cam groove 147 provided on the outer periphery 120a of the support member 120, a cam arm 148 having one end fixed to the base end 130a of the finger member 130, and a cam pin 146 erected on the other end of the cam arm 148 and having its tip housed in the cam groove 147. Note that the configuration in which the finger member 130 is pivotally supported on the outer periphery 110a of the circular member 110 by the pivot shaft 112 is the same as that of the robot hand 100.

[0047] Even with such a link mechanism 140', when the circular member 110 is rotated rightward (clockwise) in a bottom view relative to the support member 120, the cam pin 146 slides toward one end side of the cam groove 147, causing the finger member 130 to stand up relative to the circular member 110. Conversely, when the circular member 110 is rotated leftward (counterclockwise) in a bottom view relative to the support member 120, the cam pin 146 slides toward the other end side of the cam groove 147, causing the finger member 130 to lie down relative to the circular member 110. [Explanation of symbols]

[0048] 100, 100'... robot hand, 110... circular member, 111... shaft fitting hole, 112... pivot shaft, 113... bearing, 110a... outer periphery, 120... support member, 120a... outer periphery, 122... pedestal mounting portion, 130... finger member, 130a... base end, 130b... tip, 131... fitting hole, 132... pedestal mounting portion, 140, 140'... link mechanism, 141... support side ball joint, 142... rotation side ball joint, 143... joint shaft, 144... support side joint base, 145... rotation side joint base, 146... cam pin 147...cam groove, 148...cam arm, 200...robot arm, 210...hand base, 220...hand actuator, 221...hand sensor, 230...arm actuator, 231...arm sensor, 240...camera unit, 300...CPU, 301...finger control unit, 302...arm control unit, 303...object recognition unit, 310...memory, 320...communication interface, 330...graphics board, 910...plastic bottle, 911...bottle body, 911a...recessed portion, 912...cap, 921...ground surface, 921a...ground portion

Claims

1. a circular member that is rotated about a central axis by an actuator; A support member that rotatably supports the circular member; three or more finger members, each of which is pivotally supported at a base end on the outer periphery of the circular member, extends from the base end to a tip end, and is curved or bent toward the circular member at at least the tip end; a link mechanism for displacing each of the finger members between a horizontally lying state and a vertically standing state with respect to the circular member when the circular member is rotated relative to the support member; A robot hand comprising:

2. The robot hand according to claim 1 , wherein the link mechanism includes a first ball joint provided on the support member side and a second ball joint provided on the finger member side.

3. 2. The robot hand according to claim 1, wherein the link mechanism includes a cam groove provided on the support member side and a cam pin provided on the finger member side.

4. 4. The robot hand according to claim 1, wherein in the lying state, the tip end of each of the finger members overlaps with the base end of the adjacent finger member in a radial direction of the circular member.

5. The robot hand according to claim 1 , wherein in the upright position, the tip portions of the finger members converge on an extension of a central axis of the circular member.

6. The robot hand according to claim 1 , further comprising a mesh member that is suspended between adjacent ones of the finger members when the robot hand is displaced to the upright position.

7. A method for controlling a robot hand comprising: a circular member that is rotated around a central axis by an actuator; a support member that rotatably supports the circular member; and a plurality of finger members that are displaced from a horizontal state to a vertical state with respect to the circular member when the circular member is rotated relative to the support member, the method comprising: a displacement step of displacing the plurality of finger members to the lying-down state; an approaching step of bringing the robot hand closer to the object to be held based on a recessed portion of the object to be held or a grounded portion of the object to be held; a storing step of, in a process of displacing the plurality of finger members to the upright state, storing at least a portion of the held object in a holding space surrounded by the plurality of finger members and the circular member by inserting a tip portion of each of the plurality of finger members into the recessed portion or the grounding portion; a maintaining step of maintaining the holding space without displacing the plurality of finger members while the holding object is moved; A method for controlling a robot hand having the above construction.

8. The control method according to claim 7 , wherein the recessed portion includes a wire portion connecting a first portion and a second portion of the object to be held, and the holding space accommodates either the first portion or the second portion.

9. 1. A control program for a robot hand comprising: a circular member that is rotated around a central axis by an actuator; a support member that rotatably supports the circular member; and a plurality of finger members that are displaced from a horizontal state to a vertical state with respect to the circular member when the circular member is rotated relative to the support member, a displacement step of displacing the plurality of finger members to the lying-down state; an approaching step of bringing the robot hand closer to the object to be held based on a recessed portion of the object to be held or a grounded portion of the object to be held; a storing step of, in a process of displacing the plurality of finger members to the upright state, storing at least a portion of the held object in a holding space surrounded by the plurality of finger members and the circular member by inserting a tip portion of each of the plurality of finger members into the recessed portion or the grounding portion; a maintaining step of maintaining the holding space without displacing the plurality of finger members while the holding object is moved; A robot hand control program that causes a computer to execute the above.

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