Robot hand

Abstract

To provide a robot hand suitable for objects of a wide range of sizes. A robot hand (100) has a first rack and pinion mechanism (241) and a second rack and pinion mechanism (242). A first rack part (R2-1) of the second rack and pinion mechanism is fixed to a pinion part (G1) of the first rack and pinion mechanism. A pinion part (G2) of the second rack and pinion mechanism is fixed to a second rack part (R1-2) of the first rack and pinion mechanism.

Description

Robot Hand

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

[0002] Robots equipped with robotic hands for gripping objects are widely known. Robotic hands are typically used in the form of two-fingered parallel grippers. Here, a two-fingered parallel gripper refers to a robotic hand having a mechanism in which a pair of gripping portions (fingers) move toward or away from each other, gripping an object by the pair of gripping portions approaching each other. Robots equipped with such robotic hands can be used for pick-and-place operations and object fixing operations in manufacturing sites such as factories.

[0003] Known mechanisms for two-fingered parallel gripper robot hands include a link type using a bar linkage and a linear type using a linear slider. Link type and linear type robot hands are disclosed in, for example, Patent Documents 1 to 3 listed below.

[0004] Japanese Patent No. 5351161 Japanese Patent Publication No. 2021-133444 Japanese Patent Publication No. 2021-70076

[0005] In a link-type robot hand, the rotational movement of a link member extending from a base is converted into horizontal movement of a gripper attached to the tip of the link member. The opening width of the gripper is approximately 10 to 20 cm. Furthermore, the gripper does not move along a perfectly straight line, but rather along a curved line within a plane. Therefore, when the gripper grasps an object, the object is subjected to pressure from the gripper and a tangential frictional force. Therefore, there is a possibility that the gripper will not be able to grasp the object stably.

[0006] On the other hand, linear robotic hands use a linear slider to move the gripper, which moves horizontally along a straight line. Therefore, when the gripper grips an object, the object is only subjected to pressure from the gripper. Therefore, linear robotic hands have the advantage of being able to grip objects stably.

[0007] However, the movable range of the gripper in conventional linear robotic hands is limited by the length of the linear slider. Therefore, the opening width of the gripper is typically about 2 to 6 cm. To grip a large object, it is necessary to increase the length of the linear slider or use a gripper that cannot be completely closed. However, such robotic hands are disadvantageous for gripping small objects. In other words, conventional linear robotic hands have difficulty handling objects of a wide range of sizes.

[0008] An object of one aspect of the present invention is to realize a robot hand that is adaptable to objects of a wide range of sizes.

[0009] In order to solve the above-mentioned problems, a robot hand according to one aspect of the present invention includes a base, a gripping mechanism, and a drive unit, wherein the gripping mechanism has a plurality of rack and pinion mechanisms and a gripping unit, and each of the plurality of rack and pinion mechanisms has a first rack section having a first rack gear formed along a first direction, a second rack section having a second rack gear formed along the first direction, and a pinion section having a pinion gear that meshes with the first rack gear and the second rack gear, and the plurality of rack and pinion mechanisms include a first rack mechanism and a second rack mechanism. the first rack portion of the first rack and pinion mechanism is fixed to the base, the first rack portion of the second rack and pinion mechanism is driven by the drive unit to move along the first direction and is fixed to the pinion portion of the first rack and pinion mechanism, the pinion portion of the second rack and pinion mechanism is fixed to the second rack portion of the first rack and pinion mechanism, and the gripping unit is provided on the second rack portion or the first rack portion connected to the base via at least two or more of the pinion portions.

[0010] According to one aspect of the present invention, a robot hand that is adaptable to objects of a wide range of sizes can be realized.

[0011] 5 is a perspective view showing the external configuration of a robot hand in a state where a gripper is completely closed according to embodiment 1. FIG. 6 is a perspective view showing the external configuration of a robot hand in a state where a gripper is completely open according to embodiment 1. FIG. 7 is a perspective perspective view showing the configuration of a rack and pinion mechanism in a robot hand in a state where a gripper is completely closed according to embodiment 1. FIG. 8 is a perspective perspective view showing the configuration of a rack and pinion mechanism in a robot hand in a state where a gripper is completely open according to embodiment 1. FIG. 9 is a diagram schematically showing the configuration of a rack and pinion mechanism in a state where a gripper is opened from the state shown in FIG. 5 according to embodiment 1. FIG. 10 is a schematic view explaining unnecessary parts of each rack of the rack and pinion mechanism according to embodiment 2. FIG. 11 is a perspective view showing the external configuration of a robot hand in a state where a gripper is open according to embodiment 3. FIG. 12 is a perspective perspective view showing the configuration of a rack and pinion mechanism in a robot hand in a state where a gripper is open according to embodiment 3. FIG. 10 is a diagram schematically showing the configuration of the second rack and pinion mechanism in a state where the gripping portion is completely closed according to embodiment 3. FIG. 11 is an exploded perspective view showing the connection relationship of three rack and pinion mechanisms in a modified example 2. FIG. 12 is a diagram schematically showing the configuration of three rack and pinion mechanisms in a modified example 2. FIG. 13 is a diagram schematically showing the configuration of the second rack and pinion mechanism in a state where the gripping portion is completely closed according to modified example 3. FIG. 14 is a diagram schematically showing the configuration of the second rack and pinion mechanism in a state where the gripping portion is completely closed according to modified example 4. FIG. 15 is a diagram schematically showing the configuration of three rack and pinion mechanisms in a modified example 4.

[0012] [Embodiment 1] (Schematic configuration of robot hand 100) Fig. 1 is a perspective view showing the external configuration of the robot hand 100 in a state where the gripper 23 is fully closed. Fig. 2 is a perspective view showing the external configuration of the robot hand 100 in a state where the gripper 23 is fully open.

[0013] As shown in FIGS. 1 and 2, the robot hand 100 includes a base 10 (a base portion), a pair of gripping mechanisms 20-1 and 20-2, and a drive unit 30.

[0014] Each of the pair of gripping mechanisms 20-1, 20-2 has a structure that is approximately symmetrical with respect to a predetermined axis (an axis along the vertical direction). The pair of gripping mechanisms 20-1, 20-2 are provided on one side and the other side of the base 10, respectively. Hereinafter, unless there is a particular need to distinguish between them, the pair of gripping mechanisms 20-1, 20-2 will be simply referred to as gripping mechanisms 20. The same applies to each of the members provided in the pair of gripping mechanisms 20-1, 20-2.

[0015] The gripping mechanism 20 includes a linear slide unit 21, a frame unit 22, a gripping unit 23, and a rack and pinion mechanism unit 24. The linear slide unit 21 is fixed to the frame unit 22 of the gripping mechanism 20 and is a member that slides along a first direction. The frame unit 22 is a member that deploys and retracts along the first direction as the linear slide unit 21 slides. The gripping unit 23 is a member that moves along the first direction as the frame unit 22 deploys and retracts. The gripping unit 23 opens and closes to grip an object. The rack and pinion mechanism unit 24 is a member that converts driving force from the drive unit 30, which will be described later, into sliding of the linear slide unit 21.

[0016] In detail, the gripping mechanism 20-1 is connected to one side surface of the base 10, and the gripping mechanism 20-2 is connected to the other side surface of the base 10. The linear slide section 21-1 of the gripping mechanism 20-1 deploys in one direction in the first direction, and the linear slide section 21-2 of the gripping mechanism 20-2 deploys in the other direction in the first direction. As the linear slide section 21 deploys, the gripping section 23-1 of the gripping mechanism 20-1 moves in one direction in the first direction, and the gripping section 23-2 of the gripping mechanism 20-2 moves in the other direction in the first direction. As a result, the pair of gripping sections 23-1, 23-2 move apart. Similarly, as the linear slide section 21 retracts, the pair of gripping sections 23-1, 23-2 move closer to each other. In other words, the gripping section 23 performs an opening and closing operation.

[0017] Hereinafter, the first direction will be referred to as the left-right direction. Specifically, the side on which the gripping mechanism 20-1 is deployed will be referred to as the right side, and the opposite side will be referred to as the left side. Furthermore, the side of the base 10 on which the gripping mechanism 20-1 is provided will be referred to as the front side, and the opposite side will be referred to as the rear side. Furthermore, the direction in which the gripping unit 23 extends relative to the base 10 will be referred to as the upward direction, and the opposite side will be referred to as the downward direction. Furthermore, the left-right direction, the front-rear direction, and the up-down direction will also be referred to as the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively.

[0018] (Linear Slide Section) The linear slide section 21 includes a first linear slide 211, a second linear slide 212, and a third linear slide 213. The first linear slide 211, the second linear slide 212, and the third linear slide 213 are mechanisms that guide linear motion. Each of the first linear slide 211, the second linear slide 212, and the third linear slide 213 may be a linear guide or a linear bushing.

[0019] The first linear slide 211 has a first rail member 211a and a first block member 211b. The first rail member 211a is fixed to one side surface of the base 10 and has a rail portion extending in the left-right direction. The first block member 211b is fixed to the second frame 222 and has a rail engaging portion that engages with the rail portion of the first rail member 211a.

[0020] The second linear slide 212 has a second rail member 212a and a second block member 212b. The second rail member 212a is fixed to the third frame 223 and has a rail portion extending in the left-right direction. The second block member 212b is fixed to the second frame 222 and has a rail engaging portion that engages with the rail portion of the second rail member 212a.

[0021] The third linear slide 213 has a third rail member 213a and a third block member 213b. The third rail member 213a is fixed to the fourth frame 224 and has a rail portion extending in the left-right direction. The third block member 213b is fixed to the third frame 223 and has a rail engaging portion that engages with the rail portion of the third rail member 213a.

[0022] The movements of the first block member 211b, the second block member 212b, and the third block member 213b are restricted to sliding in the left and right direction by the first rail member 211a, the second rail member 212a, and the third rail member 213a, respectively.

[0023] (Frame Section) The frame section 22 includes a first frame 221, a second frame 222, a third frame 223, and a fourth frame 224. Each member of the frame section 22 is made of, for example, sheet metal. The first frame 221 is fixed to the base 10. The second frame 222 is connected to the first frame 221 via a first linear slide 211. The third frame 223 is connected to the second frame 222 via a second linear slide 212. The fourth frame 224 is connected to the third frame 223 via a third linear slide 213. The gripper 23 is fixed to the fourth frame 224.

[0024] The second frame 222 slides left and right relative to the first frame 221 in accordance with the sliding of the first linear slide 211. The third frame 223 slides left and right relative to the second frame 222 in accordance with the sliding of the second linear slide 212. The fourth frame 224 slides left and right relative to the third frame 223 in accordance with the sliding of the third linear slide 213. In this way, the frame portion 22 is deployed and retracted left and right in accordance with the sliding of the linear slide portion 21.

[0025] (Gripping section) The gripping section 23 is fixed to the fourth frame 224. In detail, the fourth frame 224 of the gripping mechanism 20-1 includes a left-right extension section 224a on which the third rail member 213a is provided, and a front-rear extension section 224b that extends rearward from the upper part of the left-right extension section 224a. The gripping section 23 is a member that extends upward from the left end of the front-rear extension section 224b. The gripping sections 23 of the pair of gripping mechanisms 20-1, 20-2 each have gripping surfaces 23a that are perpendicular to the left-right direction and overlap when viewed from the left-right direction. The gripping sections 23 grip an object by moving the gripping surfaces 23a closer to each other.

[0026] Hereinafter, the distance between the gripping surface 23a of the gripping portion 23 of the gripping mechanism 20-1 and the gripping surface 23a of the gripping portion 23 of the gripping mechanism 20-2 will be referred to as the opening width L1 of the gripping portion 23. Furthermore, the distance between the right end of the left-right extension 224a of the gripping mechanism 20-1 and the left end of the left-right extension 224a of the gripping mechanism 20-2 will be referred to as the width L2 of the robot hand. The maximum value of the opening width L1 of the gripping portion 23 is, for example, 150 mm. The maximum value of the width L2 of the robot hand is, for example, 216 mm.

[0027] In this embodiment, "the state in which the gripping portion 23 is completely closed" refers to the state in which the gripping portion 23 has the smallest opening width, and "the state in which the gripping portion 23 is completely open" refers to the state in which the gripping portion 23 has the largest opening width.

[0028] (Drive Unit) The drive unit 30 includes a motor 31 and a rack and pinion mechanism 32. The rack and pinion mechanism 32 includes a gear 321 connected to the rotation shaft of the motor 31, and a pair of rack portions 322-1 and 322-2 that mesh with the gear 321. The rack portion 322-1 is located in front of the gear 321, and the rack portion 322-2 is located in rear of the gear 321. The pair of rack portions 322-1 and 322-2 are fixed to the second frames 222 of the pair of gripping mechanisms 20-1 and 20-2, respectively.

[0029] The forward rotational drive force of the motor 31 causes the rack section 322-1 to move rightward and the rack section 322-2 to move leftward via the gear 321. Therefore, the forward rotational drive force of the motor 31 causes the second frame 222 of the gripping mechanism 20-1 to slide rightward relative to the first frame 221 and the second frame 222 of the gripping mechanism 20-2 to slide leftward relative to the first frame 221. The reverse is also true.

[0030] (Rack and pinion mechanism) Fig. 3 is a perspective view showing the configuration of the rack and pinion mechanism 24 in the robot hand 100 when the gripper 23 is fully closed. Fig. 4 is a perspective view showing the configuration of the rack and pinion mechanism 24 in the robot hand 100 when the gripper 23 is fully open.

[0031] As shown in Figures 3 and 4, the rack and pinion mechanism 24 has a first rack and pinion mechanism 241 and a second rack and pinion mechanism 242. The first rack and pinion mechanism 241 and the second rack and pinion mechanism 242 each have first rack portions R1-1 and R2-1, second rack portions R1-2 and R2-2, and pinion portions G1 and G2. The first rack portions R1-1 and R2-1 have first rack gears formed along the left-right direction. The second rack portions R1-2 and R2-2 have second rack gears formed along the left-right direction. The pinion portions G1 and G2 have pinion gears that mesh with the first rack gear and the second rack gear.

[0032] In this embodiment, the first rack gear of the second rack and pinion mechanism 242 is provided in the same orientation as the first rack gear of the first rack and pinion mechanism 241. Furthermore, the second rack gear of the second rack and pinion mechanism 242 is provided in an orientation opposite to the first rack gear of the first rack and pinion mechanism 241. In the example shown in Figures 3 and 4, the first rack portions R1-1 and R2-1 have first rack gears that face upward, and the second rack portions R1-2 and R2-2 have second rack gears that face downward.

[0033] The pinion portions G1 and G2 mesh with the first rack gear and the second rack gear between the first rack portion R1-1 and R2-1 and the second rack portion R1-2 and R2-2, respectively. In the example shown in Figures 3 and 4, the pinion portions G1 and G2 are each a single circular gear.

[0034] Here, the first rack portion R1-1 of the first rack and pinion mechanism 241 is fixed to the base 10. Furthermore, the first rack portion R2-1 of the second rack and pinion mechanism 242 is driven by the drive unit 30 to move in the left-right direction. Furthermore, the first rack portion R2-1 of the second rack and pinion mechanism 242 is fixed to the pinion portion G1 of the first rack and pinion mechanism 241. Furthermore, the pinion portion G2 of the second rack and pinion mechanism 242 is fixed to the second rack portion R1-2 of the first rack and pinion mechanism 241.

[0035] Specifically, the first rack portion R1-1 of the first rack and pinion mechanism 241 is provided on the first frame 221 fixed to the base 10. The pinion portion G1 of the first rack and pinion mechanism 241 and the first rack portion R2-1 of the second rack and pinion mechanism 242 are both provided on the second frame 222. As described above, the second frame 222 is driven by the drive unit 30, and therefore the pinion portion G1 and first rack portion R2-1 provided on the second frame 222 are also driven by the drive unit 30. The second rack portion R1-2 of the first rack and pinion mechanism 241 and the pinion portion G2 of the second rack and pinion mechanism 242 are both provided on the third frame 223. The second rack portion R2-2 of the second rack and pinion mechanism 242 is provided on the fourth frame 224.

[0036] The gripper 23 is provided on the second rack portion or the first rack portion connected to the base 10 via at least two or more pinion portions. In this embodiment, the gripper 23 is provided on the second rack portion R2-2 of the second rack and pinion mechanism 242 connected to the base 10 via two pinion portions G1 and G2. The gripper 23 is fixed to the fourth frame 224 to which the second rack portion R2-2 of the second rack and pinion mechanism 242 is attached.

[0037] (Kinematic Relationship of the Rack and Pinion Mechanism) Fig. 5 is a diagram schematically showing the configuration of the rack and pinion mechanism 24 when the gripping unit 23 is completely closed. Fig. 6 is a diagram schematically showing the configuration of the rack and pinion mechanism 24 when the gripping unit 23 is opened from the state shown in Fig. 5. Hereinafter, with reference to Figs. 5 and 6, a mechanism by which the gripping mechanism 20 is deployed and retracted by the rack and pinion mechanism 24 will be described.

[0038] The speed of the second frame 222 of the gripping mechanism 20-1 driven by a predetermined forward rotational driving force of the motor 31 is defined as v. At this time, the speed of each member of the rack and pinion mechanism 24 is as follows. Note that, hereinafter, the direction in which each member of the gripping mechanism 20 moves so as to increase the opening width of the gripping section 23 (deployment direction) is defined as the positive direction, and the opposite direction (storage direction) is defined as the negative direction.

[0039] The first rack portion R1-1 is fixed to the base 10. Therefore, the velocity v Ｒ１－１ =0.

[0040] The pinion portion G1 and the first rack portion R2-1 are fixed to the second frame 222. Therefore, the speed v of the pinion portion G1 Ｇ１ = v, and the velocity of the first rack portion R2-1 is v Ｒ２－１ = v.

[0041] Here, due to the kinematic relationship between the rack and pinion in the first rack and pinion mechanism 241, the velocity v of the second rack portion R1-2 is Ｒ１－２ =v Ｇ１ +(v Ｇ１ -v Ｒ１－１ ) = 2v. Therefore, the speed of the third frame 223 to which the second rack portion R1-2 is attached is also 2v, and the speed of the pinion portion G2 fixed to the third frame 223 is v Ｇ２ = 2v.

[0042] Furthermore, due to the kinematic relationship between the rack and pinion in the second rack and pinion mechanism 242, the speed v Ｒ２－２ =v Ｇ２ +(v Ｇ２ -v Ｒ２－１ ) = 3v.

[0043] As described above, in the rack and pinion mechanism 24, the speed can be increased in stages as the rack connected to it becomes farther away from the base 10. Therefore, the forward rotational driving force of the motor 31 causes each block member of the linear slide unit 21 to slide in the deployment direction, and the gripping mechanism 20 deploys. The same is true in reverse.

[0044] (Operation and Effect of Robot Hand 100) According to the above configuration, the robot hand 100 is provided with a plurality of rack and pinion mechanisms (two rack and pinion mechanisms in this embodiment), and the kinematic relationships between the rack and pinion mechanisms enable the frame section 22 to be deployed and retracted, and ultimately the opening and closing of the gripping section 23. Therefore, the opening width of the gripping section 23 can be expanded compared to conventional ones, while keeping the dimensions of the robot hand 100 small.

[0045] Furthermore, the opening and closing speed of the gripper 23, which opens and closes due to a predetermined rotational driving force of the motor 31, is constant regardless of the opening width of the gripper 23. Therefore, the gripping force of the gripper 23 is uniform regardless of the opening width of the gripper 23. Therefore, it is possible to eliminate unevenness in the gripping force that may occur when realizing a wide opening and closing operation of the gripper 23.

[0046] Furthermore, it is easy to specify the opening width of the gripping portion 23 relative to the rotation amount of the motor 31. Therefore, the position control of the gripping portion 23 can be achieved with a simple configuration.

[0047] (Modification 1) In the present embodiment, an example has been described in which two rack and pinion mechanisms are applied to the robot hand 100. However, the number of rack and pinion mechanisms is not limited to two, and may be three or more.

[0048] Specifically, the gripping mechanism 20 may further include a third rack and pinion mechanism. The first rack portion of the third rack and pinion mechanism is fixed to the pinion portion G2 of the second rack and pinion mechanism 242. The pinion portion of the third rack and pinion mechanism is fixed to the second rack portion R2-2 of the second rack and pinion mechanism 242. In this case, the gripping unit 23 is provided on the second rack portion of the third rack and pinion mechanism. Note that the gripping unit 23 may also be provided on the first rack portion of the third rack and pinion mechanism (connected to the base 10 via the two pinion portions G1 and G2).

[0049] [Embodiment 2] Another embodiment of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0050] Fig. 7 is a schematic diagram illustrating unnecessary parts of each rack of the rack and pinion mechanism 24. Reference numeral 701 in Fig. 7 is a schematic diagram illustrating the configuration of the rack and pinion mechanism 24 and the gripping unit 23 when the gripping unit 23 is fully closed. Reference numeral 702 in Fig. 7 is a schematic diagram illustrating the configuration of the rack and pinion mechanism 24 and the gripping unit 23 when the gripping unit 23 is opened from the state shown by reference numeral 701 in Fig. 7.

[0051] In this embodiment, as shown by the reference numeral 701 in Figure 7, when the gripping portion 23 is completely closed, the ends of the second rack portions R1-2 and R2-2 in the deployment direction are each located closer to the storage direction than the ends of the first rack portions R1-1 and R2-1 in the deployment direction.

[0052] More specifically, when the gripping mechanism 20 deploys, the pinion portion G1 displaces on the rack gear of the second rack portion R1-2 in the storage direction. Therefore, when the gripping portion 23 is fully closed, the pinion portion G1 only engages with the rack gear on the storage direction side of the contact point on the rack gear of the second rack portion R1-2, and does not engage with the rack gear on the deployment direction side of the contact point. Therefore, there is no problem even if the portion of the second rack portion R1-2 (unnecessary portion) on the deployment direction side of the contact point on the rack gear of the second rack portion R1-2 is removed.

[0053] Furthermore, when the gripping mechanism 20 deploys, the pinion portion G2 displaces in the deployment direction on the rack gear of the first rack portion R2-1 and in the storage direction on the rack gear of the second rack portion R2-2. Therefore, when the gripping portion 23 is fully closed, it is possible to remove the portion of the first rack portion R2-1 (unnecessary portion) that is located on the storage direction side of the contact point on the rack gear of the first rack portion R2-1. Also, when the gripping portion 23 is fully closed, it is possible to remove the portion of the second rack portion R2-2 (unnecessary portion) that is located on the deployment direction side of the contact point on the rack gear of the second rack portion R2-2.

[0054] With this configuration, it is possible to reduce the width L2 of the robot hand when the gripping mechanism 20 is deployed. In particular, by removing unnecessary portions of each rack section described above, it is possible to prevent the rack section from protruding beyond the gripping section 23 in the deployment direction. This reduces the possibility that the rack and pinion mechanism 24 will affect the gripping operation (for example, the rack section will interfere with the object) when the gripping section 23 grips an object.

[0055] [Embodiment 3] Another embodiment of the present invention will be described below. For the sake of convenience, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0056] The rack and pinion mechanism 24 shown in the second embodiment has room for further improvement as follows. That is, when the gripper 23 is slightly opened from a completely closed state, the end of the first rack unit R2-1 shown in the second embodiment on the deployment direction side may protrude beyond the gripper 23 in the deployment direction. Therefore, when gripping a relatively small object, the first rack unit R2-1 may affect the gripping operation. In this embodiment, a robot hand 100A equipped with a rack and pinion mechanism 24A that can avoid such a situation will be described.

[0057] (Schematic Configuration of Robot Hand 100A) Fig. 8 is a perspective view showing the external configuration of the robot hand 100A when the gripper is open. Fig. 9 is a perspective see-through view showing the configuration of the rack and pinion mechanism 24A in the robot hand 100A when the gripper is open.

[0058] 8 and 9, the robot hand 100 includes a base 10, a pair of gripping mechanisms 20A-1 and 20A-2, and a drive unit 30. Each of the pair of gripping mechanisms 20A-1 and 20A-2 has a structure that is approximately symmetrical with respect to a predetermined axis (an axis along the vertical direction). Hereinafter, unless there is a particular need to distinguish between them, the pair of gripping mechanisms 20A-1 and 20A-2 will be simply referred to as gripping mechanisms 20A. The same applies to each of the members included in the pair of gripping mechanisms 20A-1 and 20A-2.

[0059] The gripping mechanism 20A includes a linear slide unit 21, a frame unit 22, a gripping unit 23, and a rack and pinion mechanism unit 24A. The rack and pinion mechanism unit 24A has a first rack and pinion mechanism 241 and a second rack and pinion mechanism 242A. The second rack and pinion mechanism 242A has a first rack unit R2-1A, a second rack unit R2-2A, and a pinion unit G2A. The first rack unit R2-1A has a first rack gear formed along the left-right direction. The second rack unit R2-2A has a second rack gear formed along the left-right direction. The pinion unit G2A has a pinion gear that meshes with the first rack gear and the second rack gear.

[0060] In this embodiment, the first rack gear and the second rack gear of the second rack and pinion mechanism 242A are both oriented to face the first rack gear of the first rack and pinion mechanism 241. That is, the teeth of the first rack gear and the teeth of the second rack gear of the second rack and pinion mechanism 242A are both oriented downward. The pinion portion G2A of the second rack and pinion mechanism 242A has a gear G21A (first gear) and a gear G22A (second gear) that rotates in the opposite direction to the gear G21A. The first rack gear of the second rack and pinion mechanism 242A meshes with the gear G21A, and the second rack gear of the second rack and pinion mechanism 242A meshes with the gear G22A directly or indirectly so as to rotate in conjunction with the rotation of the gear G21A. 8 and 9, the gear G22A meshes with the gear G21A. That is, the pinion portion G2A is made up of two circular gears (gears G21A and G22A). The gear G22A may also indirectly mesh with the gear G21A via an even number of gears.

[0061] Similar to the first embodiment, the first rack portion R2-1A of the second rack and pinion mechanism 242A is provided on the second frame 222 together with the pinion portion G1 of the first rack and pinion mechanism 241. The pinion portion G2A of the second rack and pinion mechanism 242A is provided on the third frame 223 together with the second rack portion R1-2 of the first rack and pinion mechanism 241. The second rack portion R2-2A of the second rack and pinion mechanism 242A is provided on the fourth frame 224.

[0062] As in the second embodiment, unnecessary portions of the first rack portion R2-1 of the first rack and pinion mechanism 241 are removed. Unnecessary portions of the first rack portion R2-1A and the second rack portion R2-2A of the second rack and pinion mechanism 242A are also removed.

[0063] (Kinematic Relationship of the Rack and Pinion Mechanism) Figure 10 is a diagram showing a schematic configuration of the second rack and pinion mechanism 242A when the gripping section 23 is fully closed. The speed of the second frame 222 of the gripping mechanism 20A driven by a predetermined forward rotational driving force of the motor 31 is v. At this time, the speed v of the first rack section R2-1A isＲ２－１Ａ = v. Also, the speed v of the second rack portion R1-2 of the first rack and pinion mechanism 241 Ｒ１－２ = 2v, the speed v of the pinion part G2A of the second rack and pinion mechanism 242A Ｇ２Ａ Furthermore, due to the kinematic relationship between the rack and pinion in the second rack and pinion mechanism 242A, the speed of the second rack portion R2-2A is v Ｒ２－２Ａ =v Ｇ２Ａ +(v Ｇ２Ａ -v Ｒ２－１Ａ ) = 3v.

[0064] As described above, in the rack and pinion mechanism 24A, as in the rack and pinion mechanism 24 according to the first embodiment, the speed can be increased stepwise as the rack connected to the rack is further away from the base 10. Therefore, as in the first embodiment, the gripping mechanism 20 is deployed by the forward rotational driving force of the motor 31. The same is true in reverse.

[0065] (Operation and Effects of the Robot Hand 100A) In the robot hand 100A according to this embodiment, multiple gears are meshed between the first rack portion R2-1A and the second rack portion R2-2A of the second rack and pinion mechanism 242A. This allows the first rack portion R2-1A to be positioned closer to the storage direction than the first rack portion R2-1 according to the first embodiment. This prevents the first rack portion R2-1A from protruding beyond the gripper 23 in the deployment direction when the gripper 23 is slightly opened from its fully closed state. Furthermore, when the gripper 23 is slightly opened from its fully closed state, the width L2 of the robot hand is almost the same as the opening width L1 of the gripper 23 (see FIG. 7). This further reduces the possibility that the rack and pinion mechanism 24 will affect the gripping operation when the gripper 23 grasps an object.

[0066] In this embodiment, two gears are meshed between the first rack portion R2-1A and the second rack portion R2-2A of the second rack and pinion mechanism 242A. By minimizing the number of gears meshing between the first rack portion R2-1A and the second rack portion R2-2A in this way, energy loss and transmission error can be reduced. Furthermore, the volume occupied by the second rack and pinion mechanism 242A can be reduced. Furthermore, maintenance can be made easier.

[0067] (Modification 2) In the present embodiment, an example has been described in which two rack and pinion mechanisms are applied to the robot hand 100A. However, the number of rack and pinion mechanisms is not limited to two, and may be three or more.

[0068] Fig. 11 is an exploded perspective view showing the connection relationship of the three rack and pinion mechanisms. Fig. 12 is a diagram showing a schematic configuration of the three rack and pinion mechanisms. Reference numeral 1201 in Fig. 12 indicates the configuration of the three rack and pinion mechanisms when the gripping unit 23 is fully closed. Reference numeral 1202 in Fig. 12 indicates the configuration of the three rack and pinion mechanisms when the gripping unit 23 is opened from the state shown by reference numeral 1201 in Fig. 12.

[0069] 11 and 12, the rack and pinion mechanism 24A may further include a third rack and pinion mechanism 243A. The third rack and pinion mechanism 243A has a configuration similar to that of the second rack and pinion mechanism 242A. That is, the third rack and pinion mechanism 243A includes a first rack portion R3-1A having a downward-facing first rack gear, a second rack portion R3-2A having a downward-facing second rack gear, and a pinion portion G3A including a gear G31A (first gear) and a gear G32A (second gear).

[0070] 11, the first rack portion R3-1A of the third rack and pinion mechanism 243A is fixed to the gear G22A of the second rack and pinion mechanism 242A. Furthermore, the gear G31A of the third rack and pinion mechanism 243A is fixed to the second rack portion R2-2A of the second rack and pinion mechanism 242A. In this case, the gripper 23 is provided on the second rack portion R3-2A of the third rack and pinion mechanism 243A. Note that the gripper 23 may also be provided on the first rack portion R3-1A of the third rack and pinion mechanism 243A (connected to the base 10 via the two pinion portions G1 and G2).

[0071] As shown in FIG. 12, the first rack portion R3-1A of the third rack and pinion mechanism 243A is fixed to the gear G22A of the second rack and pinion mechanism 242A, and therefore the speed v Ｒ３－１Ａ =v Ｇ２Ａ Furthermore, since the pinion portion G3A of the third rack and pinion mechanism 243A is fixed to the second rack portion R2-2A of the second rack and pinion mechanism 242A, the speed v Ｇ３Ａ =v Ｒ２－２Ａ Furthermore, due to the kinematic relationship between the rack and pinion in the third rack and pinion mechanism 243A, the speed v Ｒ３－２Ａ =v Ｇ３Ａ +(v Ｇ３Ａ -v Ｒ３－１Ａ ) = 4v.

[0072] Therefore, by providing the gripping portion 23 on the second rack portion R3-2A of the third rack and pinion mechanism 243A, the opening width of the gripping portion 23 can be further increased.

[0073] 13 is a diagram schematically illustrating the configuration of the second rack and pinion mechanism 242B when the gripper 23 is completely closed. The robot hand 100 according to the first embodiment may include the second rack and pinion mechanism 242B shown in FIG. 13 instead of the second rack and pinion mechanism 242.

[0074] The second rack and pinion mechanism 242B has a first rack portion R2-1, a second rack portion R2-2, and a pinion portion G2B. The pinion portion G2B has a gear G21B (third gear) and a gear G22B (fourth gear) that rotates in the same direction as the gear G21B. The first rack gear of the second rack and pinion mechanism 242B meshes with the gear G21B, and the second rack gear of the second rack and pinion mechanism 242B meshes with the gear G22B. The gear G22B indirectly meshes with the gear G21B so as to rotate in conjunction with the rotation of the gear G21B. In the example shown in FIG. 13 , the pinion portion G2B further has a gear G23B. The gear G23B meshes with the gears G21B and G22B. The gear G22B may indirectly mesh with the gear G21B via an odd number of gears.

[0075] According to this configuration, the first rack portion R2-1 can be disposed closer to the storage direction side than in embodiment 1. Therefore, it is possible to prevent the first rack portion R2-1 from protruding beyond the grip portion 23 in the deployment direction side.

[0076] 14 is a diagram schematically illustrating the configuration of the second rack and pinion mechanism 242C when the gripper 23 is completely closed. The robot hand 100A according to the third embodiment may include a second rack and pinion mechanism 242C shown in FIG. 14 instead of the second rack and pinion mechanism 242A.

[0077] The second rack and pinion mechanism 242C has a first rack portion R2-1A, a second rack portion R2-2A, and a pinion portion G2C. The pinion portion G2C has a compound gear including a gear G21C (fifth gear) on the first rack portion R2-1A side and a gear G22C (sixth gear) on the second rack portion R2-2A side. The gears G21C and G22C rotate around the same axis. The diameter of the gear G21C is different from the diameter of the gear G22C.

[0078] The second rack and pinion mechanism 242C also has a gear G23C that meshes with the gear G22C of the compound gear. The first rack gear of the second rack and pinion mechanism 242C meshes with the gear G21C of the compound gear, and the second rack gear of the second rack and pinion mechanism 242C meshes with the gear G23C.

[0079] FIG. 15 is a diagram schematically illustrating the configuration of the three rack and pinion mechanisms. Reference numeral 1501 in FIG. 15 indicates the configuration of the three rack and pinion mechanisms when the gripper 23 is fully closed. Reference numeral 1502 in FIG. 15 indicates the configuration of the three rack and pinion mechanisms when the gripper 23 is opened from the state indicated by reference numeral 1501 in FIG. 15. In FIG. 15, the three rack and pinion mechanisms consist of a first rack and pinion mechanism 241, a second rack and pinion mechanism 242C, and a third rack and pinion mechanism 243C. The third rack and pinion mechanism 243C has a configuration similar to that of the second rack and pinion mechanism 242C.

[0080] The speed of the second frame 222 of the gripping mechanism 20A driven by a predetermined forward rotational driving force of the motor 31 is defined as v. At this time, the speed of the first rack portion R2-1A of the second rack and pinion mechanism 242C is v Ｒ２－１Ａ = v. Also, the speed v of the pinion part G2C of the second rack and pinion mechanism 242C is Ｇ２Ｃ Furthermore, if the speed transmission ratio of the compound gear is λ, the speed v of the second rack portion R2-2A of the second rack and pinion mechanism 242C is determined by the kinematic relationship between the rack and pinion in the second rack and pinion mechanism 242C. Ｒ２－２Ａ =v Ｇ２Ｃ +λ(v Ｇ２Ｃ -v Ｒ２－１Ａ ) = (1 + λ)2v - λv. Here, the speed transmission ratio λ = r2 / r1, where r1 is the diameter of the gear G21C and r2 is the diameter of the gear G22C. Similarly, the speed v of the second rack portion R3-2A of the third rack and pinion mechanism 243C Ｒ３－２Ａ = (1 + λ) ((1 + λ) 2v - λv) - 2v.

[0081] With this configuration, the speed of the second rack portion R2-2A can be changed, compared to the second rack and pinion mechanism 242A according to the third embodiment, which does not have a compound gear. This allows the opening width of the grip portion 23 relative to the rotational driving force of the motor 31 to be adjusted.

[0082] The above-described compound gear configuration may be applied to the rack and pinion mechanism of the robot hand 100 according to the first and second embodiments. Furthermore, at least one of the multiple pinion gears may have a compound gear.

[0083] (Summary) In order to solve the above-mentioned problems, a robot hand according to aspect 1 of the present invention includes a base, a gripping mechanism, and a drive unit, the gripping mechanism has a plurality of rack and pinion mechanisms and a gripping unit, each of the plurality of rack and pinion mechanisms has a first rack section having a first rack gear formed along a first direction, a second rack section having a second rack gear formed along the first direction, and a pinion section having a pinion gear that meshes with the first rack gear and the second rack gear, the first rack portion of the first rack and pinion mechanism is fixed to the base, the first rack portion of the second rack and pinion mechanism is driven by the drive unit to move along the first direction and is fixed to the pinion portion of the first rack and pinion mechanism, the pinion portion of the second rack and pinion mechanism is fixed to the second rack portion of the first rack and pinion mechanism, and the gripping unit is provided on the second rack portion or the first rack portion connected to the base via at least two or more of the pinion portions.

[0084] In a robot hand according to aspect 2 of the present invention, in the above aspect 1, the first rack gear and the second rack gear of the second rack and pinion mechanism are both arranged in a direction opposite to the first rack gear of the first rack and pinion mechanism, the pinion portion of the second rack and pinion mechanism has a first gear and a second gear that rotates in the opposite direction relative to the first gear, the second gear rotates in the opposite direction relative to the first gear in conjunction with the rotation of the first gear, the first rack gear of the second rack and pinion mechanism meshes with the first gear, and the second rack gear of the second rack and pinion mechanism meshes with the second gear.

[0085] In a robot hand according to aspect 3 of the present invention, in the above-described aspect 1, the first rack gear of the second rack and pinion mechanism may be arranged in the same direction as the first rack gear of the first rack and pinion mechanism, the second rack gear of the second rack and pinion mechanism may be arranged in a direction opposite to the first rack gear of the first rack and pinion mechanism, the pinion portion of the second rack and pinion mechanism may have a third gear and a fourth gear that rotates in the same direction as the third gear, the fourth gear rotates in the same direction as the third gear in conjunction with the rotation of the third gear, the first rack gear of the second rack and pinion mechanism may mesh with the third gear, and the second rack gear of the second rack and pinion mechanism may mesh with the fourth gear.

[0086] In a robot hand according to Aspect 4 of the present invention, in Aspects 1 to 3 above, at least one of the pinion portions may have a compound gear.

[0087] In a robot hand according to Aspect 5 of the present invention, in Aspect 2 above, the second gear may mesh with the first gear.

[0088] In a robot hand according to aspect 6 of the present invention, in the above aspects 1 to 5, the plurality of rack and pinion mechanisms may further include a third rack and pinion mechanism, the first rack portion of the third rack and pinion mechanism being fixed to the pinion portion of the second rack and pinion mechanism, and the pinion portion of the third rack and pinion mechanism being fixed to the second rack portion of the second rack and pinion mechanism.

[0089] In the robot hand according to aspect 7 of the present invention, in the above aspects 1 to 6, if the direction in which each member of the gripping mechanism moves so as to increase the opening width of the gripping portion is defined as the deployment direction and the opposite direction is defined as the storage direction, when the opening width of the gripping portion is at its smallest, the end of the second rack portion in the deployment direction may be positioned closer to the storage direction than the end of the first rack portion in the deployment direction corresponding to the second rack portion.

[0090] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0091] 100, 100A Robot hand 10 Base (base) 20, 20A Grip mechanism 23 Grip section 24, 24A Rack and pinion mechanism section 30 Drive section 241 First rack and pinion mechanism 242, 242A, 242B, 242C Second rack and pinion mechanism 243A, 243C Third rack and pinion mechanism R1-1, R2-1, R2-1A, R3-1A First rack section R1-2, R2-2, R2-2A, R3-2A Second rack section G1, G2, G2A, G2B, G2C, G3A, G3C Pinion section G21A, G31A Gear (first gear) G22A, G32A Gear (second gear) G21B Gear (third gear) G22B Gear (4th Gear) G21C, G31C Gear (5th Gear) G22C, G32C Gear (6th Gear)

Claims

1. A device comprising: a base; a gripping mechanism; and a drive unit, wherein the gripping mechanism has a plurality of rack and pinion mechanisms and the gripping unit, wherein each of the plurality of rack and pinion mechanisms has: a first rack section having a first rack gear formed along a first direction; a second rack section having a second rack gear formed along the first direction; and a pinion section having a pinion gear that meshes with the first rack gear and the second rack gear, wherein the plurality of rack and pinion mechanisms include a first rack and pinion mechanism and a second rack and pinion mechanism, wherein the first rack section of the first rack and pinion mechanism is fixed to the base, wherein the first rack section of the second rack and pinion mechanism is driven by the drive unit to move along the first direction and is fixed to the pinion section of the first rack and pinion mechanism, and wherein the pinion section of the second rack and pinion mechanism is fixed to the second rack section of the first rack and pinion mechanism, The gripping portion is provided on the second rack portion or the first rack portion, which is connected to the base portion via at least two or more of the pinion portions.

2. The robot hand described in claim 1, wherein the first rack gear and the second rack gear of the second rack and pinion mechanism are both arranged in a direction opposite to the first rack gear of the first rack and pinion mechanism, the pinion portion of the second rack and pinion mechanism has a first gear and a second gear that rotates in the opposite direction relative to the first gear, the second gear rotates in the opposite direction relative to the first gear in conjunction with the rotation of the first gear, the first rack gear of the second rack and pinion mechanism meshes with the first gear, and the second rack gear of the second rack and pinion mechanism meshes with the second gear.

3. A robot hand as described in claim 1, wherein the first rack gear of the second rack and pinion mechanism is arranged in the same direction as the first rack gear of the first rack and pinion mechanism, and the second rack gear of the second rack and pinion mechanism is arranged in a direction opposite to the first rack gear of the first rack and pinion mechanism, the pinion portion of the second rack and pinion mechanism has a third gear and a fourth gear that rotates in the same direction as the third gear, and the fourth gear rotates in the same direction as the third gear in conjunction with the rotation of the third gear, and the first rack gear of the second rack and pinion mechanism meshes with the third gear, and the second rack gear of the second rack and pinion mechanism meshes with the fourth gear.

4. A robot hand according to any one of claims 1 to 3, wherein at least one of the pinion portions has a compound gear.

5. The robot hand according to claim 2, wherein the second gear meshes with the first gear.

6. A robot hand as described in any one of claims 1 to 3, wherein the plurality of rack and pinion mechanisms further include a third rack and pinion mechanism, the first rack portion of the third rack and pinion mechanism being fixed to the pinion portion of the second rack and pinion mechanism, and the pinion portion of the third rack and pinion mechanism being fixed to the second rack portion of the second rack and pinion mechanism.

7. A robot hand as claimed in any one of claims 1 to 3, wherein, when the direction in which each member of the gripping mechanism moves so as to increase the opening width of the gripping section is defined as the deployment direction and the opposite direction as the storage direction, when the opening width of the gripping section is at its smallest, the end of the second rack section in the deployment direction is located closer to the storage direction than the end of the first rack section in the deployment direction that corresponds to the second rack section.

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