JP2009166181A - Robot hand - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a robot hand stably gripping an object. <P>SOLUTION: A robot hand of the present invention has a palm link 20 and a plurality of finger links 10 connected to the palm link. A gripping surface is formed of a material having flexibility in at least a part of a surface for gripping an object in a finger link 10 and a palm link 20, and on the gripping surface, a friction coefficient of the gripping surface of the palm link is set to be 1.7 or less, and the friction coefficient of the gripping surface of the palm link is set to be not more than the friction coefficient of the gripping surface of the finger link. Fine irregularities are formed on the surface of the gripping surface, to adjust the friction coefficient. The finger link 10 has a root side link 11 connected to the palm link 20 and a finger tip side link 12 connected to the root side link 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a robot hand for holding an object.

  Conventionally, for example, Patent Documents 1 to 3 describe robot hands that hold objects. In the robot hand described in Patent Document 1, the tip finger portion, the first finger portion, and the second finger portion are connected so as to be bendable. A surface material having a relatively large friction coefficient is attached to the inside of the tip finger portion, and a surface material having a small friction coefficient is attached to the inside of the first and second finger portions which are the base side finger portions. Yes. The object to be grasped is caught by being caught by a tip finger portion having a large friction coefficient. And in the 1st and 2nd finger part whose friction coefficient is smaller than a tip finger part, a grasped object moves, sliding. Thereby, movement and positioning of the object to be grasped are performed.

  Also, in the robot hand described in Patent Document 2, the grip surface at the tip of the finger link is a region having a large friction coefficient, and the root grip surface is a region having a small friction coefficient. Further, the grip surface of the palm link connected to the finger link is a region having a small friction coefficient. And an object is stably hold | gripped with the front-end | tip part holding surface with a large friction coefficient. Furthermore, when the angle of the tip part with respect to the base part of the finger is changed, the object slides in a region having a small friction coefficient, and the object moves smoothly.

Further, Patent Document 3 discloses a robot hand in which an uneven shape (dimple shape) in which a concave portion is formed on the surface of a finger portion is formed. By forming the recess, the coefficient of friction of the finger is improved, and the object is stably held.
JP 2002-264066 A JP-A-6-143179 JP 2005-88096 A

  However, in the robot hands described in Patent Documents 1 and 2, emphasis is placed on gripping an object to be gripped at the finger tip. For this reason, when a desired gripping force is obtained at the tip of the finger, a torque larger than that required for gripping the gripping object on the base side of the finger is required. This increases the size of the actuator.

  Further, in the robot hand described in Patent Document 3, the contact area between the object and the finger part is increased and the coefficient of friction of the finger part is improved by the uneven shape (dimple shape) in which the concave portion is formed. An object can be easily gripped by improving the friction shape. However, depending on the material of the finger part, when the contact area between the object and the finger part is increased to improve the friction coefficient, the object may be fixed by the finger part having a large friction coefficient. As a result, there is a problem in that the object cannot be gripped at a desired position and stable gripping may not be performed.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a robot hand that can stably hold an object.

  The robot hand according to the present invention has a palm link and a plurality of finger links connected to the palm link, and has flexibility in at least a part of the palm link and a surface of the finger link that grips an object. A gripping surface is formed from a material, and among the gripping surfaces, a friction coefficient of the gripping surface of the palm link is 1.7 or less, and a friction coefficient of the gripping surface of the finger link is a friction of the gripping surface of the palm link. The coefficient of friction is adjusted by adjusting the surface roughness to an appropriate value not less than the coefficient.

  In the present invention, the gripping surface is formed on the surface for gripping an object so that the gripping surface is made of a material having flexibility and the friction coefficient of the gripping surface of the finger link is equal to or greater than the friction coefficient of the gripping surface of the palm link. The friction coefficient is adjusted by increasing the surface roughness of the material. By this. When the grasped object is grasped, the grasped object can easily move to a stable position on the palm, and the grasped object can be grasped well.

  Further, the palm side of the finger link and the grip surface of the palm may be provided with irregularities. The friction coefficient can be reduced by providing irregularities on the root and palm of the finger link.

  Furthermore, it is possible to provide unevenness on the entire gripping surface of the finger link and palm so that the friction coefficient of the gripping surface of the palm is smaller than the gripping surface of the finger link. Irregularities may be provided on the entire gripping surface.

  Furthermore, the finger link may include a root side link connected to the palm link and a fingertip side link connected to the root side link. By configuring the finger link from a plurality of links, it is possible to grip a more complex or small gripping object.

  The gripping surface may have a hardness of 90 durometer (A) or less. The friction coefficient can be adjusted by adjusting the surface roughness of the material having a hardness of 90 durometer (A) or less.

  Further, of the gripping surfaces, the surface roughness of the grip surface of the palm link has an unevenness average interval RSm of 20 μm to 1 mm, an unevenness average height Rc of 2 μm or more, and the gripping surface of the finger link The surface roughness can be smaller than the surface roughness of the grip surface of the palm link. Thereby, a friction coefficient can be adjusted.

  Furthermore, the flexible gripping surface can be made of rubber or a resin material, and is preferably silicon rubber.

  In addition, a sheet made of the flexible material is pasted on the surface of the finger link and the palm link on the side where the object is gripped, or the finger link and the palm link are It can be covered with the material which has property. The gripping surface may be affixed with a sheet or a glove.

  ADVANTAGE OF THE INVENTION According to this invention, the robot hand which can hold | grip an object stably can be provided.

  Embodiment 1 FIG. Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a robot hand 1 according to a first embodiment of the present invention. As shown in FIG. 1, the robot hand 1 is formed by connecting a plurality of finger links 10 to a palm link 20.

  A plurality of links are connected to the finger link 10. In the present embodiment, the finger link 10 includes a root side link 11 connected to the palm link 20 and a fingertip side link 12 connected to the root side link. By configuring the finger link 10 from the root side link 11 and the fingertip side link 12, the contact area with the gripping object can be increased, and the gripping object can be gripped more stably.

  The root side link 11 of the finger link 10 is connected to the palm link 20. The fingertip side link 12 is connected to the side opposite to the side to which the palm link 20 is connected in the root side link 11. The root side link 11, the fingertip side link 12, and the palm link 20 are respectively connected via a joint shaft 30. Each joint shaft 30 is connected to an actuator (not shown), and the angle of the root side link 11 and the fingertip side link 12 with respect to the palm link 20 changes by driving the actuator. In this manner, the gripping object is gripped by changing the angles of the root side link 11 and the fingertip side link 12 with respect to the palm link 20.

  Each link has a gripping surface for gripping a gripped object. The root side link 11 has a gripping surface 11a (hereinafter referred to as a root side gripping surface 11a). The fingertip side link 12 has a gripping surface 12a (hereinafter referred to as fingertip side gripping surface 12a). The palm link 20 has a gripping surface 20a (hereinafter referred to as a palm gripping surface 20a). These gripping surfaces are made of a material having flexibility. Among the gripping surfaces, the friction coefficient of the gripping surface of the palm link 20 is 1.7 or less, and the friction coefficient of the gripping surface of the finger link 10 is the palm link. It is more than the friction coefficient of 20 grip surfaces. For example, the material having flexibility preferably has a hardness of 90 durometer (A) or less. As such a material, for example, rubber or resin material is preferable, and silicon rubber is more preferable. The friction coefficient can be adjusted by forming irregularities on the surface of such a flexible material as silicon rubber. For example, the surface roughness of the grip surface of the palm link is about 20 μm to 1 mm, and the surface roughness of the grip surface of the finger link 10 is about 2 μm or more. It is desirable that the surface roughness of the grip surface of the link 20 is smaller. That is, by providing unevenness on the surface of the flexible material, the friction coefficient of the palm gripping surface 20a is set to 1.7 or less, and the friction coefficient of the fingertip side gripping surface is set to be equal to or greater than the friction coefficient of the palm side gripping surface. When the grasped object is grasped, the grasped object moves moderately on the palm and becomes easy to grasp.

  Here, also in the past, the friction coefficient of the root-side gripping surface 11a is made smaller than the friction coefficient of the fingertip-side gripping surface 12a. As a result, the grasping object is grasped by the fingertip side grasping surface 12a having a larger friction coefficient than the palm grasping surface 20a, and the grasped object is slid by the palm grasping surface 20a having a smaller friction coefficient than the fingertip side grasping surface 12a. Move the object. In this case, for example, fluororesin (Teflon (registered trademark)) or the like has been used for the palm gripping surface 20a in order to make the friction coefficient smaller than that of the fingertip side gripping surface 12a. When a gripping object is gripped by a robot hand using fluororesin or the like on the palm gripping surface 20a, the friction coefficient is remarkably reduced when the surface of the gripping object is, for example, paper, wood, metal, or hard resin. However, when the surface of the grasped object is silicon rubber or the like, the friction coefficient remains extremely large due to the adsorption phenomenon between the silicon rubber and the fluororesin. For this reason, the friction coefficient is increased depending on the material of the surface of the gripped object, and thus the gripping behavior is greatly different. As a result, gripping becomes unstable and gripping control becomes complicated.

  Therefore, in this embodiment, a material having flexibility is applied to the gripping surface, and fine roughness is provided on the surface to adjust the surface roughness and adjust the friction coefficient of the gripping surface. More specifically, by forming fine irregularities on the palm gripping surface 20a, the friction coefficient is set to 1.7 or less, and the friction coefficient is set to be equal to or higher than the fingertip side gripping surface. Alternatively, as will be described later, by forming fine irregularities on the palm gripping surface 20a and the root gripping surface 11a, the friction coefficient is set to 1.7 or less, and the friction coefficient is set to be equal to or greater than the fingertip gripping surface. Alternatively, at least the unevenness formed on the surface of the palm gripping surface 20a is made larger than the unevenness formed on the fingertip side gripping surface 12a so that the friction coefficient of the palm gripping surface 20a is smaller than the friction coefficient of the fingertip side gripping surface 12a. Thereby, in addition to the case where the surface of the gripping object is paper, wood, metal, hard resin, or the like, the friction coefficient with the gripping object can be reduced also in the case of silicon rubber or the like. That is, the change in the friction coefficient due to the difference in the material of the surface of the gripping object can be reduced, and the gripping object can be gripped stably. For this reason, control of holding becomes easy.

  As described above, in order to grip the gripping object at a desired position, the friction coefficient of the grip surface of the palm link is set to 1.7 or more, and the friction coefficient of the grip surface of the finger link 10 is set to the grip surface of the palm link 20. More than the friction coefficient. For this reason, when the palm gripping surface 20a has a friction coefficient larger than 1.7, the palm gripping surface 20a also has a friction coefficient as large as the gripping surface of the finger link, and grips the gripping object at a desired position. Is difficult. That is, the grasped object is fixed to the palm grasping surface 20a, and it is difficult to grasp at a desired position. For this reason, the surface roughness of the palm gripping surface is adjusted so that the friction coefficient of the gripping surface is 1.7 or less and the friction coefficient of the fingertip side gripping surface or less. Thereby, in addition to the case where the surface of the gripping object is paper, wood, metal, hard resin, or the like, the friction coefficient can be reduced even in the case of silicon rubber or the like, depending on the difference in the material of the gripping object. The change in the friction coefficient can be reduced, and the grasped object can be grasped stably. And grip control can be easily performed.

  Further, by making the surface roughness of the root side gripping surface 11a substantially the same as the surface roughness of the fingertip side gripping surface 12a and making the friction coefficient of the root side gripping surface 11a larger than the palm gripping surface 20a, the root side gripping surface 11a. In this case, a sufficient frictional force can be obtained, and the grasped object can be grasped stably. Further, since the grasped object can be grasped on the root-side grasping surface 11a in addition to the fingertip-side grasping surface 12a, the driving torque of the joint shaft 30a that connects the root-side link 11 and the palm link 20 is reduced. Can do. Thereby, in the actuator connected to the joint shaft 30 and having a speed reducer or the like, the speed reducer or the like can be reduced, so that the actuator can be reduced in size and the size of the robot hand 1 can be reduced. it can.

  As described above, conventionally, since the emphasis was on the grip on the fingertip side of the robot hand, a large driving torque was required. In this case, a reduction gear with a large gear is required, and the actuator is enlarged accordingly. On the other hand, in the present embodiment, the driving torque of the joint shaft 30a that connects the root side link 11 and the palm link 20 is increased by increasing the friction coefficient of the root side gripping surface 11a in the same manner as the fingertip side gripping surface 12a. Can be reduced. Therefore, the gear of the reduction gear can be reduced, the actuator can be reduced in size, and the dimensions of the robot hand 1 can be reduced. When the robot hand 1 is small, it is possible to greatly reduce the interference with the surrounding environment when the robot hand 1 grips and moves the gripped object.

  Next, the configuration of the robot hand 1 and the configuration of each gripping surface in the present embodiment will be described in detail. The link length between the joint axes 30 in the root side link 11 of the robot hand 1 can be approximately 55 mm. The link length between the joint shaft 30 in the fingertip side link 12 and the end opposite to the side on which the joint shaft 30 is formed can be approximately 55 mm. Moreover, the link length between the joint axes 30 in the palm link 20 can be approximately 70 mm. Further, the movable range of the root side link 11 and the fingertip side link 12 connected by the joint shaft 30 is approximately 0 degrees or more when the fully open state parallel to the palm link 20 is an angle of 0 degrees. The fingertip side link 12 is set to approximately 0 degree or more and +90 degrees or less with +120 degrees or less.

  The gripping surface of each link is formed using silicon rubber. For the palm gripping surface 20a, the average unevenness height (ISO4287 / 1) Rc defined by JISB0601 is 2 μm, for example, and the average interval of the unevenness (from the roughness curve, the reference length l is extracted in the direction of the average line. A sum of lengths of average lines corresponding to a mountain and one adjacent valley is obtained, and the average value is expressed in millimeters: Sm = 1 / nΣSmi) RSm can be set to 20 to 1000 μm, for example. Here, it is particularly preferable that the average unevenness interval RSm = 50 to 300 μm and the average unevenness height Rc = 5 μm or more.

  Further, the root side gripping surface 11a and the fingertip side gripping surface 12a are smooth surfaces with an arithmetic average roughness Ra of, for example, 0.4 μm or less and an average unevenness height of, for example, 1.5 μm or less. 2A shows a cross-sectional view of the palm gripping surface 20a, and FIG. 2B shows a cross-sectional view of the root-side gripping surface 11a and the fingertip side gripping surface 12a. By configuring the gripping surface of each link as described above, the palm gripping surface 20a has minute protrusions as shown in FIG. 2A, and the root-side gripping surface 11a and the fingertip-side gripping surface 12a. Becomes a smooth surface as shown in FIG.

  When the surface of the gripping object is paper, wood, metal, hard resin, or silicon rubber, the friction coefficient between the gripping object and each gripping surface is the palm gripping surface 20a. It is approximately 0.5 to 1.6, and is approximately 1.2 m to 6.0 for the root side gripping surface 11a and the fingertip side gripping surface 12a. The robot hand 1 having such a configuration causes the surface of the gripped object to grip paper, wood, metal, hard resin, or silicon rubber. When the finger link 10 is operated, the grasped object can be grasped at a desired position without being fixed by the palm grasping surface 20a, and grasping control can be easily performed. In addition, the grasped object can be stably grasped regardless of the difference in the material of the surface of the grasped object.

  Here, as a comparative example, a case will be described in which the palm gripping surface 20a and the root side gripping surface 11a and the fingertip side gripping surface 12a are set to have substantially the same average unevenness height Rc = 1.5 μm. At this time, the gripping object is made of paper, wood, metal, hard resin, or silicon rubber, and the finger link 10 is operated. In this case, when the surface of the gripping object is metal, hard resin, or silicon rubber, the gripping object is fixed by the palm gripping surface 20a. For this reason, it is difficult to grip a gripped object at a desired position and to perform stable gripping. In addition, it becomes difficult to control the gripping of the gripped object.

  Further, as another comparative example, the material of the palm gripping surface 20a is a conventionally used fluororesin plate, and the material of the root side gripping surface 11a and the fingertip side gripping surface 12a is a smooth surface of silicon rubber. In this case, if the surface of the gripping object is paper, wood, metal, hard resin, or silicon rubber, the friction coefficient between the palm gripping surface 20a and the gripping object is approximately 0.1 to 6.0, and the fundamental side The coefficient of friction between the gripping surface 11a and the fingertip side gripping surface 12a and the gripping object is approximately 1.2 to 6.0. Therefore, when the gripping object is gripped by the robot hand in this comparative example and the finger link 10 is operated, the gripping object is fixed on the palm gripping surface 20a because the friction coefficient is large when the surface of the gripping object is silicon rubber. Therefore, it becomes difficult to grasp it well. That is, when a fluororesin processed plate is used, depending on the material of the surface of the gripped object, gripping at a desired position cannot be performed, stable gripping cannot be performed, and gripping control becomes difficult.

  In the present embodiment, a gripping surface is formed of a material having flexibility on at least a part of the surface of the finger link 10 and the palm link 20 that grips an object. The surface roughness is adjusted so that the friction coefficient of the grip surface of the palm link is 1.7 or less and the friction coefficient of the grip surface of the finger link or less. In this way, by adjusting the surface roughness of the flexible material and adjusting the friction coefficient, it is possible to reduce the change in the friction coefficient due to the difference in the material of the surface of the gripping object, and grip it at the desired position. An object can be gripped. For this reason, a grasped object can be grasped stably. Also, gripping control can be easily performed. Further, in the present embodiment, since a minute protrusion is not provided on the root-side gripping surface 11a, the root-side gripping surface 11a has sufficient frictional force to grip the gripped object more stably. Can do.

Embodiment 2. FIG.
Next, a second embodiment will be described. In the first embodiment, the friction coefficient with the gripping object is different between the root side gripping surface 11a and the fingertip side gripping surface 12a and the palm gripping surface 20a. However, in the second embodiment, the fingertip side gripping surface 12a The friction coefficient is made different between the side gripping surface 11a and the palm gripping surface 20a. The fingertip side gripping surface 12a is defined as a smooth surface with the same definition as the average unevenness height Rc of JISB0601 defined by the root side gripping surface 11a and the fingertip side gripping surface 12a of the first embodiment, for example. In addition, the root side gripping surface 11a and the palm gripping surface 20a are defined in the same manner as the average unevenness height Rc and the average interval Sm of the unevenness defined by the palm gripping surface 20a of the first embodiment, for example. Form.

In the present embodiment, a material whose hardness of each gripping surface is 90 or more is used, and the surface roughness of the gripped object is made different between the fingertip side gripping surface 12a, the root side gripping surface 11a, and the palm gripping surface 20a. For example, minute irregularities are provided on the palm gripping surface 20a and the root-side gripping surface 11a. As a result, the change in the friction coefficient due to the difference in the material of the surface of the grasped object can be reduced, and the grasped object can be grasped at a desired position without being fixed by the palm grasping surface 20a. . For this reason, a grasped object can be grasped stably. And grip control can be easily performed. However, in Embodiment 2, since the surface roughness of the root-side gripping surface 11a is roughened, the friction coefficient of the root-side gripping surface 11a is reduced as compared with Embodiment 1. For this reason, the driving torque of the joint shaft 30a that connects the root side link 11 and the palm link 20 is required to be approximately twice that in the case of the first embodiment.
Embodiment 3 FIG.

  Next, Embodiment 3 will be described. In the third embodiment, as in the first embodiment, the friction coefficient is made different between the root side gripping surface 11a and the fingertip side gripping surface 12a and the palm gripping surface 20a. Here, in Embodiment 1, a minute protrusion is formed only on the palm gripping surface 20a. However, in Embodiment 3, the root side gripping surface 11a, the fingertip side gripping surface 12a, and the palm gripping surface 20a Each is provided with a minute protrusion. In this case, when the surface of the gripping object is paper, wood, metal, hard resin, or silicon rubber, the coefficient of friction between the gripping object and each gripping surface is, for example, approximately 0.5 to 0.8 on the palm gripping surface 20a. The friction coefficient of the root side gripping surface 11a and the fingertip side gripping surface 12a is, for example, approximately 1.0 to 1.7.

  In the present embodiment, by forming minute irregularities on the root side gripping surface 11a, the fingertip side gripping surface 12a, and the palm gripping surface 20a, the change in the friction coefficient due to the difference in the material of the gripped object can be reduced. The gripping object can be gripped at a desired position without being fixed by the palm gripping surface 20a. For this reason, the gripping object can be stably gripped. And grip control can be easily performed. However, in the present embodiment, since minute protrusions are also provided on the root-side gripping surface 11a and the fingertip-side gripping surface 12a, the root-side gripping surface 11a and the fingertip-side gripping surface 12a are compared with those in the first embodiment. Although the frictional force decreases, the frictional force for gripping the gripping object is sufficiently secured.

  It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

It is a figure which shows the robot hand concerning embodiment of this invention. (A) is a schematic diagram showing an enlarged gripping surface of the palm link of the robot hand in the first embodiment, and (b) is a schematic diagram showing an enlarged gripping surface of the finger link of the robot hand in the first embodiment. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Robot hand 10 Finger link 11 Root side link 11a Root side holding surface 12 Finger tip side link 12a Finger tip side holding surface 20 Palm link 20a Palm holding surface 30 Joint axis

Claims (10)

Palm links,
A plurality of finger links connected to the palm link;
A gripping surface is formed from a material having flexibility on at least a part of a surface of the palm link and the finger link that grips an object, and a friction coefficient of the gripping surface of the palm link among the gripping surfaces is 1.7. A robot hand in which the friction coefficient of the grip surface of the finger link is equal to or greater than the friction coefficient of the grip surface of the palm link and the friction coefficient is adjusted by making the surface roughness appropriate. The robot hand according to claim 1, wherein an unevenness is provided on a root of the palm side of the finger link and the gripping surface of the palm. 3. The robot hand according to claim 2, wherein unevenness is provided on the entire gripping surface of the finger link and the palm so that a friction coefficient of the palm gripping surface is smaller than a gripping surface of the finger link. The robot hand according to any one of claims 1 to 3, wherein the finger link includes a root side link connected to the palm link and a fingertip side link connected to the root side link. . The robot hand according to any one of claims 1 to 4, wherein the gripping surface has a hardness of 90 durometer (A) or less. Among the gripping surfaces, the surface roughness of the gripping surface of the palm link has an unevenness average interval RSm of 20 μm to 1 mm and an unevenness average height Rc of 2 μm or more. The robot hand according to any one of claims 1 to 5, wherein the height is smaller than a surface roughness of a gripping surface of the palm link. The robot hand according to any one of claims 1 to 6, wherein the gripping surface having flexibility is made of rubber or a resin material. The robot hand according to any one of claims 1 to 7, wherein the gripping surface having flexibility is silicon rubber. The robot hand according to any one of claims 1 to 8, wherein a sheet made of the flexible material is pasted on a surface of the finger link and the palm link on a side where an object is gripped. . The robot hand according to any one of claims 1 to 8, wherein the finger link and the palm link are covered with the flexible material.

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