Robot hand

Abstract

To provide a robot hand which enables improvement of flexibility in selection of an attitude of each finger part while inhibiting increase in size of the robot hand.SOLUTION: A robot hand 1 includes: a plurality of finger parts 3 having a restoration part for generating a restoration force acting to an initial attitude side at which the finger parts 3 extend; wires 5 each of which is attached at one end to a tip of the finger part 3 and causes a tensile force to act on the finger part 3 toward the operation attitude side at which the finger part 3 is bent; pulleys 9 which tow the other ends of the wires 5; and a motor 12 which drives the pulleys 9. Each of the finger parts 3 includes a magnetic substance 8 at a tip, and an electromagnet is provided in a portion which contacts with the tip of the finger part 3 at the operation attitude. When a force applied by the pulley 9 to tow the wire 5 is reduced in a state of the operation attitude, the magnetic substance 8 and the electromagnet are fixed by a magnetic force.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a robot hand having multiple fingers. [Background technology]

[0002] Patent Documents 1 and 2 describe a robot hand that has five fingers, a first wire that is guided through a ventral path of each finger, and a second wire that is guided through a dorsal path of each finger, and is configured so that the fingers can bend or extend by winding up either the first wire or the second wire.

[0003] In the robot hand described in Patent Document 1, a columnar member to which one end of each first wire is connected and a columnar member to which one end of each second wire is connected are fixed to a single pulley, and the pulley is further provided with a wire pushing hook that presses and guides a predetermined portion of the first wire so as to increase the pulling amount of the first wire when the pulley rotates in a direction to wind the first wire, and that presses and guides a predetermined portion of the second wire so as to increase the pulling amount of the second wire when the pulley rotates in a direction to wind the second wire. Note that the robot hand is configured so that adjustments can be made, such as bending a predetermined finger later than the other fingers, by making the amount of bending of the wire attached to a predetermined finger greater in the initial state than the amount of bending of the wires attached to the other fingers.

[0004] Furthermore, the robot hand described in Patent Document 2 is equipped with motors and pulleys in a number corresponding to the number of fingers, and is configured so that the fingers can be individually bent or extended by individually controlling the motors provided for each finger. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-167049 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-39656 Summary of the Invention [Problem to be solved by the invention]

[0006] The robot hand described in Patent Document 1 is configured to bend or extend five fingers using a single motor and pulley, so it is not possible to selectively set different postures for each finger, such as bending selected fingers and extending others, which may limit the degree of freedom in selecting the posture of the fingers.On the other hand, the robot hand described in Patent Document 2 is equipped with a motor for each finger, so while it is possible to bend or extend fingers individually by selecting the motor to control, the overall configuration of the robot hand may become larger.

[0007] This invention was devised with an eye on the above-mentioned technical problems, and aims to provide a robot hand that can increase the degree of freedom in selecting the posture of the fingers while preventing the device from becoming too large. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a robot hand comprising a plurality of fingers on which a restoring force acts in a direction that results in a bent or extended initial posture, pulling members attached at one end to the tip of each of the fingers and applying tension to the fingers toward the bent or extended operating posture that is different from the initial posture, pulling units that pull the other ends of the pulling members, and actuators that drive the pulling units, wherein the robot hand comprises a plurality of locking mechanisms corresponding to each of the plurality of fingers that selectively maintain the operating posture when the pulling force of the pulling units on the pulling members is reduced in the operating posture state.

[0009] The initial position in this invention may include a position in which the finger portion is extended, and the locking mechanism may be composed of an electromagnet and a magnetic body, one of the electromagnet and the magnetic body being provided on a holding part that contacts the finger portion in the operating position in which the finger portion is bent, and the other of the electromagnet and the magnetic body being provided on a part of the finger portion that contacts the holding part.

[0010] The locking mechanism in the present invention may be configured to selectively clamp an intermediate portion of the tension member in the longitudinal direction. [Effects of the Invention]

[0011] The robot hand of the present invention is configured so that the restoring forces acting on the multiple fingers cause the fingers to assume an initial bent or extended position, and by driving the actuators, the pulling members attached to each finger are pulled by the traction units, causing the fingers to assume an operating position different from the initial bent or extended position. In other words, each finger can be bent or extended by a single actuator.

[0012] Furthermore, when the traction force of the pulling member by the traction unit is reduced in the above-described operating posture, multiple locking mechanisms are provided corresponding to the fingers, selectively maintaining the operating posture. Therefore, by controlling the actuator to reduce the amount of traction on the pulling member, only the fingers locked by the locking mechanisms can maintain the operating posture. That is, a bent state and an extended state can be individually selected for each finger. Therefore, the robot hand can assume complex postures without providing multiple actuators for bending or extending the fingers. In other words, the degree of freedom in selecting the posture of the robot hand can be improved. Furthermore, the number of actuators that impose high mechanical and electrical loads can be reduced, improving the maintainability and durability of the robot hand. This can reduce the cost, size, and weight of the robot hand, and further reduce the required current. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram schematically illustrating a configuration of a robot hand according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram for explaining the functions of a control system for a robot hand. [Figure 3] 4 is a flowchart illustrating an example of control executed by a controller. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following embodiments of the present invention will be described with reference to the accompanying drawings. Note that the following embodiments are merely examples of specific embodiments of the present invention and are not intended to limit the scope of the present invention.

[0015] FIG. 1 shows a schematic diagram of an example of a robot hand according to an embodiment of the present invention. The robot hand 1 shown in FIG. 1 is configured to resemble a human hand. Specifically, the robot hand 1 includes a base 2 that resembles a palm and five finger portions 3a, 3b, 3c, 3d, and 3e that resemble five fingers protruding from the base 2. Specifically, the robot includes a first finger portion 3a that resembles a thumb, a second finger portion 3b that resembles an index finger, a third finger portion 3c that resembles a middle finger, a fourth finger portion 3d that resembles a ring finger, and a fifth finger portion 3e that resembles a little finger. Note that the basic configuration of each of the finger portions 3a, 3b, 3c, 3d, and 3e is the same, and therefore, in the following description, they may be simply referred to as "finger portion 3" without distinguishing between them.

[0016] The base portion 2 and the finger portions 3 are integrally formed of an elastic material such as rubber so that the finger portions 3 are in an extended state in an initial state when no external force is applied. That is, the finger portions 3 are configured so that a restoring force acts in the extension direction. The finger portions 3 are also provided with ridges 4. The ridges 4 are provided to increase the second moment of area of ​​the finger portions 3 so that, when tension acts on the tip of the finger portions 3 from a wire 5 (described later), the bending position of the finger portions 3 is determined closer to the tip of the finger portions 3 than the ridges 4. That is, the first finger portion 3a is provided with one ridge 4 at a predetermined distance from the tip of the first finger portion 3a, and the second to fifth finger portions 3b to 3e are provided with two ridges 4 side by side at a predetermined distance from the tips of the fingers 3b, 3c, 3d, and 3e, respectively.

[0017] Similarly, a ridge 6 is formed along the outer edge of the base 2 at the boundary between the base 2 and the three fingers. Therefore, similar to the ridge 4 provided on the fingers 3, when tension acts on the tip of the fingers 3, the fingers 3 are configured to bend relative to the base 2 at the boundary between the base 2 and the three fingers.

[0018] One end of a tensile member (hereinafter referred to as a wire) 5 made of natural or chemical fibers is attached to the tip of the finger 3. This wire 5 is stretched along the surface of the robot hand 1, i.e., the surface corresponding to the palm, toward the end of the robot hand 1 (the part corresponding to the wrist). Specifically, each of the ridges 4, 6 has a through-hole formed in its width direction (the longitudinal direction of the finger 3), and the wire 5 is passed through the through-hole and stretched toward the end of the robot hand 1. That is, the ridges 4, 6 have the function of guiding the wire 5 in addition to the function of bending the finger 3 in an imitation of a joint.

[0019] The thickness of the tip of the finger 3 is formed to be approximately the same as the thickness at the top of the ridge 4, and a recess 7 of a predetermined depth is formed in the center. A magnetic body 8 made of a metal material or the like is attached to the recess 7. The magnetic body 8 shown in FIG. 1 is composed of a disk portion and a protrusion (not shown) that fits into the recess 7, and is fixed to the tip of the finger 3 by fitting the protrusion into the recess 7. For ease of explanation, FIG. 1 shows the magnetic body 8 attached only to the second finger 3b.

[0020] In the robot hand 1 described above, the fingers 3 are bent at the ridges 4 and 6 as bending points by winding and pulling the wire 5. That is, the robot hand 1 assumes a fist-like posture. In the following description, the fist-like posture is referred to as the operating posture. A mechanism for putting the robot hand 1 into such an operating posture, in other words, a mechanism for pulling all of the wires 5 to apply tension to all of the fingers 3 and bend them, is provided.

[0021] Specifically, there are provided a first pulley 9a for winding the wire 5 attached to the first finger 3a, a second pulley 9b for winding the wire 5 attached to the second finger 3b, a third pulley 9c for winding the wire 5 attached to the third finger 3c, a fourth pulley 9d for winding the wire 5 attached to the fourth finger 3d, and a fifth pulley 9e for winding the wire 5 attached to the fifth finger 3e. These pulleys 9a, 9b, 9c, 9d, and 9e correspond to "pulling units" in the embodiment of the present invention, and since the basic configuration of each of the pulleys 9a, 9b, 9c, 9d, and 9e is the same, in the following description they may be simply referred to as "pulley 9" without distinguishing between the fingers.

[0022] These pulleys 9 are arranged side by side on a rotating shaft 10. That is, when the rotating shaft 10 rotates, all of the pulleys 9 rotate together and wind up all of the wires 5. In other words, all of the fingers 3 are bent from an extended state. Note that the amount of wire 5 required to wind up the robot hand 1 to assume the operating posture differs depending on the length of the fingers 3 (i.e., the length of the wire 5), so the diameter (minimum diameter) of the winding portion of the pulley 9 may be made larger as the length of the fingers 3 increases.

[0023] A motor 12, which corresponds to the "actuator" in the embodiment of this invention, is connected to the rotating shaft 10 via a reduction gear pair 11. That is, a drive gear 11a is attached to the output shaft 13 of the motor 12, and a driven gear 11b, which meshes with the drive gear 11a and has a large diameter, is attached to the rotating shaft 10. Therefore, the rotation of the motor 12 is reduced and transmitted to the rotating shaft 10, so that the finger 3 can be bent to a desired angle by appropriately controlling the rotation angle (number of rotations) of the motor 12. Note that a configuration may also be adopted in which multiple rotating shafts are provided, each with a pulley attached, and the gear ratio between the motor and the rotating shaft is changed according to the length of the corresponding finger.

[0024] Furthermore, when the robot hand 1 is in the operating posture, recesses 14 are formed in the base portion 2 at positions that come into contact with the tips of the fingers 3, and electromagnets (not shown) are fitted into the recesses 14. These electromagnets can be constructed by winding a coil around a core of magnetic material such as an iron core. For convenience, only the recesses 14 are shown in FIG. 1. The locations where the recesses 14 are formed correspond to the "holding portions" in this embodiment of the present invention.

[0025] Fig. 2 shows a block diagram for explaining the function of the control system of the robot hand 1. Note that the dashed lines in Fig. 2 indicate control signals. The control system shown in Fig. 2 includes a controller 16 that controls the motors 12 and electromagnets 15 provided for each of the fingers 3 based on the posture required of the robot hand 1. This controller 16 is mainly composed of a conventionally known microcomputer, and is configured to receive signals from various sensors provided in the robot and determine command signals to be output to the motors 12 and electromagnets 15 based on the input signals and pre-stored arithmetic expressions, maps, etc.

[0026] 2 also includes a DC power supply (hereinafter simply referred to as a power supply) 17 that supplies power to the motor 12 and the electromagnet 15, and a plurality of relays 18 that selectively connect or cut off the supply of power from the power supply 17 to the electromagnet 15. For ease of explanation, FIG. 2 shows a relay 18a provided corresponding to the first finger portion 3a and a relay 18b provided corresponding to the second finger portion 3b.

[0027] Then, by outputting command signals determined by the controller 16 to the motor 12 and the relays 18a and 18b, power is supplied to the motor 12 and the electromagnet 15. The command signals to the motor 12 include a command signal for operating the motor 12 in a direction to bend the finger 3, in other words, in a direction to wind up the wire 5, and a command signal for operating the motor 12 in a direction to extend the finger 3, in other words, in a direction to reduce the amount of wire 5 wound up.

[0028] Therefore, when the motor 12 is operated and the pulley 9 winds up the wire 5, each finger 3 is bent via the wire 5. Furthermore, when power is supplied to the electromagnet 15, the magnetic body 8 provided on each finger 3 and the electromagnet 15 are fixed together by magnetic force, so that even when the motor 12 is operated from the operating posture to reduce the amount of wire 5 wound up, the finger 3 fixed by magnetic force maintains that posture. In other words, the magnetic body 8 and the electromagnet 15 constitute a locking mechanism that maintains the operating posture of the finger 3.

[0029] Fig. 3 shows a flowchart for explaining an example of control executed by the controller 16. The control example shown in Fig. 3 is executed when the power supply of the robot is turned on and the controller 16 and an amplifier (not shown) are started up. First, initial settings are made (step S1), and the motor 12 is operated to assume an operating posture (step S2). That is, by operating the motor 12 to wind up the wire 5, all of the fingers 3 are brought into a bent state.

[0030] Next, a pose is determined (step S3). For example, in the case where the user and the robot are playing "rock-paper-scissors," step S3 determines one of the following postures: a paper posture corresponding to the initial posture in which all the fingers 3 are extended, a rock posture corresponding to the operating posture in which all the fingers 3 are bent, and a scissors posture in which the second finger 3b and the third finger 3c are extended and the other fingers 3a, 3d, and 3e are bent.

[0031] Next, based on the pose determined in step S3, it is determined whether or not to extend the first finger 3a (step S4), and if the first finger 3a is not extended and the determination in step S4 is negative, the electromagnet 15a corresponding to the first finger 3a is turned on (step S5). That is, the magnetic body 8a provided at the tip of the first finger 3a and the electromagnet 15a are fixed by magnetic force.

[0032] If the answer to step S4 is affirmative by extending the first finger 3a, or if the answer to step S5 is negative by not extending the second finger 3b, the electromagnet 15b corresponding to the second finger 3b is turned on (step S7). That is, the magnetic body 8b provided at the tip of the second finger 3b and the electromagnet 15b are fixed together by magnetic force.

[0033] For ease of explanation, FIG. 3 shows a determination as to whether or not to extend the first finger portion 3a and the second finger portion 3b, but a determination as to whether or not to extend the five fingers 3 is made in the same manner, and for a finger portion 3 that is determined not to be extended, the electromagnet 15 corresponding to that finger portion 3 is turned on.

[0034] If the answer to step S6 is YES by extending the second finger 3b, or following step S6, it is determined whether or not all fingers 3 are to be extended. For any finger 3 that is not to be extended, the electromagnet 15 corresponding to that finger 3 is turned on, and then the motor 12 is operated to return that finger 3 to its initial position (step S8), and this routine is temporarily terminated. That is, the tension of all wires 5 is reduced.

[0035] In the robot hand 1 configured as described above, in an initial posture in which no current is applied to the motor 12 or the electromagnet 15, the fingers 3 are maintained in an extended state due to the elastic force (restoring force) of the material that constitutes the robot hand 1. In this state, by operating the motor 12 and winding up the wire 5, all of the fingers 3 are bent, and the robot hand 1 changes to a fist-shaped operating posture.

[0036] In such an operating posture, a finger 3 that maintains a bent state is selected, and by energizing the electromagnet 15 corresponding to the selected finger 3, a magnetic force is generated between the magnetic body 8 provided at the tip of the finger 3 and the electromagnet 15. Therefore, by operating the motor 12 in a direction that reduces the amount of winding of the wire 5, only the selected finger 3 maintains a bent state. That is, a bent state or an extended state can be individually selected for each finger 3. Therefore, complex postures, such as the scissors posture in rock-paper-scissors, can be taken without providing multiple motors 12 as actuators for bending or extending the fingers 3. In other words, the degree of freedom in selecting postures of the robot hand 1 can be improved. Furthermore, the number of motors 12, which have high mechanical and electrical loads, can be reduced, improving the maintainability and durability of the robot hand 1. This also allows the robot hand 1 to be reduced in cost, size, and weight, and further reduces the required current.

[0037] The locking mechanism in the embodiments of the present invention is not limited to one that uses magnetic force to fix the magnetic body 8 provided at the tip of the finger 3 to the electromagnet 15 provided on the base 2, as long as it can maintain the operating position of the finger 3. Specifically, the electromagnet and the magnetic body may be disposed in the recess 14 of the base 2 so as to face each other and be able to move toward and away from each other, with the wire 5 passing between the electromagnet and the magnetic body. In other words, the locking mechanism may be provided in the middle of the wire 5 in the longitudinal direction.

[0038] By configuring it in this manner, the wire 5 is clamped and fixed by the magnetic force between the electromagnet and the magnetic body, so that even if the amount of wire 5 wound by the pulley 9 is reduced, bending of the wire 5 between the tip of the finger 3 and the position where it is clamped by the electromagnet and the magnetic body can be prevented.In other words, a decrease in the tension in the wire 5 on the tip side of the finger 3 can be prevented.

[0039] Therefore, by energizing the electromagnet corresponding to the finger 3 that maintains the operating posture and reducing the traction force of the wire 5 in that state, the selected finger 3 can maintain the bent operating posture while the other finger 3 can be extended, thereby achieving the same effect as above. That is, the locking mechanism in the embodiment of the present invention is not limited to a configuration that fixes the finger and the base, but may also be a configuration that fixes the middle portion of the wire 5 so as to maintain the tension of the wire 5 or suppress bending of the wire 5.

[0040] Furthermore, the robot hand according to the embodiment of the present invention may be configured such that all of the fingers 3 are bent as an initial posture, and the fingers 3 are pulled in a direction to be extended by the wire 5. In this case, the wire 5 may be stretched and arranged along the back surface of the robot hand 1, i.e., the surface corresponding to the back of the hand, and a locking mechanism for fixing the wire 5 may be provided at the middle of the wire 5.

[0041] Furthermore, the base 2 and fingers 3 of the robot hand 1 are not limited to those made of elastic materials, but may be made of rigid materials such as metal materials, and may be provided with rigid materials at the parts corresponding to the joints, and may have rotating parts at the parts corresponding to the joints. In this case, springs may be provided at the rotating parts so that the restoring force of the springs causes the fingers to assume an extended or bent initial position.

[0042] Furthermore, the pulling unit in the embodiments of the present invention is not limited to the pulley 9 that winds up the wire 5, but may be configured to pull the wire 5 in the axial direction (longitudinal direction) of an arm (not shown) to which the robot hand 1 is attached. Furthermore, the "actuator" in the embodiments of the present invention is not limited to the motor 12, and may be configured by other actuators such as a linear actuator that drives in a straight line, as long as it is capable of driving the part that pulls the wire 5. Furthermore, the motor 12, reduction gear pair 11, or pulley 9 may be provided in a position other than the robot hand 1, such as a robot arm, or may be provided in the base unit 2. [Explanation of symbols]

[0043] 1. Robot Hand 2 Base 3,3a,3b,3c,3d,3e fingers 5 wire 8,8a,8b Magnetic material 9,9a,9b,9c,9d,9e Pulleys 12 motors 15,15a,15b Electromagnet

Claims

1. a plurality of finger portions on which a restoring force acts in a direction to return the finger portions to their bent or extended initial posture; a tension member having one end attached to a tip of each of the finger portions and applying tension to the finger portions toward the bent or extended operating posture different from the initial posture; a pulling portion for pulling the other end of each of the tension members; an actuator that drives the traction unit, a plurality of locking mechanisms corresponding to the plurality of finger portions, which selectively maintain the operating posture when the traction force of the pulling member by the traction portion is reduced in the operating posture; A robotic hand characterized by:

2. The robot hand according to claim 1, the initial posture includes a posture in which the finger portions are extended, the locking mechanism is composed of an electromagnet and a magnetic body, One of the electromagnet and the magnetic body is provided on a holding portion that comes into contact with the finger portion when the finger portion is in the operating posture in which the finger portion is bent, and the other of the electromagnet and the magnetic body is provided on a portion of the finger portion that comes into contact with the holding portion. A robotic hand characterized by:

3. The robot hand according to claim 1, The locking mechanism is configured to selectively clamp a longitudinal intermediate portion of the tension member. A robotic hand characterized by:

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