JP4997078B2 - Robot hand - Google Patents

Description

  The present invention relates to a robot hand.

Robot hands are assembled in various industrial robots, humanoid robots, etc. and used in various fields. Robot hands have been mainly used to grip an object having a predetermined shape from a predetermined direction. In recent years, robot hands having multi-finger robot hands have been developed, and it is possible to hold an object of any shape from any direction by a multi-finger robot hand having multiple degrees of freedom and perform various operations. Can do. Fingertips for gripping objects in robot hand fingers are formed in various shapes such as cone type, hemisphere at the tip of the finger and cylinder type connected to the hemisphere, square type, other types such as having a flat part, etc. (Refer to patent document 1 etc.).
Japanese Patent Laid-Open No. 10-15871 JP-A-4-304988 JP 2000-254884 A

  Similar to a human finger, the friction coefficient (and hence the frictional force) of a flexible material such as silicon rubber used on the surface of the finger of the robot hand changes in proportion to the contact area with the object. Therefore, when the object is stably held, it is necessary to increase the contact area and the frictional force. On the other hand, when skillfully manipulating or holding an object while sliding, it is necessary to reduce the contact area and the frictional force. However, the conventional fingertip shape cannot achieve both stability and skill when grasping an object.

  For example, when the fingertip is of the circular thrust type, a sufficient gripping area cannot be secured, so that stable gripping is difficult. In the case of the hemisphere + cylinder type, since the curvature is uniform in the hemispherical portion at the tip of the finger, the contact area cannot be changed up to about 45 ° from the vertical direction of the fingertip. In the case of a square type or a type having a flat part, the flat part of the fingertip can secure a sufficient contact area when the object is gripped and can stably hold the object. In this case, the contact area becomes extremely small, and a sufficient contact area cannot be secured. For this reason, the frictional force also changes greatly due to the large change in the contact area, so that it is easy to drop an object when changing or manipulating it from one plane part to another plane part.

  Therefore, an object of the present invention is to provide a robot hand having a finger that has both stability and skill when grasping an object.

The robot hand according to the present invention is a robot hand having a plurality of fingers, and the plurality of fingers includes a first finger and a second finger having different shapes of gripping portions of the object at the fingertip, There are a plurality of fingers, the curvature of the tip of the fingertip is larger than that of the second finger and the curvature of the center of the fingertip is smaller than that of the second finger, and the contact area with respect to the contact angle with the object when gripping the object greater than the degree of change is a second finger, the second finger is located a plurality of curvature of the fingertip of the tip curvature of the central portion of the small and the fingertip than the first finger is rather larger than the first finger, When gripping an object, the degree of change of the contact area with respect to the contact angle with the object is smaller than that of the first finger, and when gripping an object that requires skill, a plurality of first fingers are used and stability is required. Patent the use of the second finger of the plurality of the time that the object grasping To.

  This robot hand has a plurality of fingers including a first finger and a second finger with different shapes of the gripping portion of the object at the fingertip, and the first finger and the second finger have a curvature configuration. Is different. The first finger has an elliptical shape that has a curvature at the tip of the fingertip that is greater than that of the second finger and a curvature at the center that is smaller than that of the second finger and is relatively close to a perfect circle. Therefore, the degree of change of the contact area with respect to the contact angle with the object is large when gripping the object, and the frictional force with the object can be freely adjusted from a small region to a large region depending on which part of the fingertip contacts. , Excellent in elaborateness. On the other hand, the second finger has an elliptical shape that is relatively close to a rectangle and has a curvature at the tip of the fingertip that is smaller than that of the first finger and a curvature at the center that is greater than that of the first finger. Therefore, the degree of change of the contact area with respect to the contact angle with the object is small when the object is gripped, and a sufficient frictional force with the object can be obtained at any part of the fingertip, and the gripping stability is excellent. As described above, this robot hand has a first finger and a second finger with different curvature configurations of the grip portion of the object at the fingertip, and by using these two types of fingers properly, stability when gripping the object is achieved. It is possible to achieve both sexiness and sophistication. In addition, the front-end | tip part in a fingertip is a fingertip part in a fingertip (end node). The central portion of the fingertip is a portion on the middle node side of the tip portion at the fingertip (end node).

  In the robot hand of the present invention, the finger may have a thickness that is set based on the curvature of the grip portion of the object. As the wall thickness is thinner, the force is more likely to be applied directly, so it is suitable for fine work that requires high precision (for example, work for holding, changing, or manipulating small objects). On the other hand, the thicker the wall is, the more it can be deformed in accordance with the shape of the object, which is suitable for stably grasping the object. Therefore, with a finger that achieves both stability and sophistication due to the curvature configuration of the fingertip as described above, the stability and sophistication when grasping can be further improved by increasing the thickness based on the curvature. .

  In particular, in the robot hand of the present invention, it is preferable that the wall thickness is larger when the curvature is large than when the curvature is small. Since the object can be stably gripped in the portion having a large curvature, the gripping stability can be further improved by increasing the thickness. On the other hand, since the object can be manipulated skillfully in the portion where the curvature is small, the elaboration can be further improved by reducing the thickness.

  In the robot hand of the present invention, the curvature is preferably the curvature of the tip of the fingertip in the sagittal plane and / or the frontal plane. The sagittal plane is a plane obtained by viewing the fingertip from the side direction. The frontal face is a face when the fingertip is viewed from the front direction, and the nails are on the upper side and the belly of the finger is on the lower side.

  According to the present invention, by having a plurality of fingers with different fingertip curvature configurations, both stability and elaboration when grasping an object can be achieved.

  Hereinafter, an embodiment of a robot hand according to the present invention will be described with reference to the drawings.

  In this embodiment, the robot hand according to the present invention is applied to a robot hand with four fingers. In this embodiment, there are two forms, the first embodiment is a form having two types of fingertips having different curvature configurations, and the second embodiment is a fingertip in the first embodiment. It is a form which sets the thickness of a coating | coated part based on a curvature. In this embodiment, since there is a feature in the fingertips (end points) of each finger of the robot hand, only the fingertip will be described in detail. Moreover, in this Embodiment, let the side surface in a fingertip be an xy plane. Moreover, in this Embodiment, a curvature is a curvature of the front-end | tip part of the fingertip in a sagittal surface (surface which looked at the fingertip from the side surface direction).

  The robot hand according to the present embodiment includes a structure part, a sensor part, and a covering part. The structure portion includes a link mechanism, a joint mechanism, an actuator, and the like, and is formed of a hard material such as aluminum. The structural part is composed of a terminal node (fingertip), a middle node and a proximal node, a palm, and a thumb ball, and each part operates by driving a joint mechanism with an actuator. The sensor unit is provided on the palm side of the surface of the structure unit, and includes a distributed pressure sensor or the like. The sensor unit is provided at least at the last node used when gripping an object. The sensor unit is a sensor that detects where and how much the object is in contact with the robot hand and how much pressure the object is in contact with. The covering portion is on the palm side of the surface of the structure portion, is provided on the upper side of the sensor portion, and is made of a covering material. The covering portion is provided at least at the terminal node used when gripping the object, and is provided at a portion in contact with the object. The covering material is formed of a soft material (a material softer than at least the structure portion), and is made of, for example, gel or silicon rubber. The covering portion deforms when it comes into contact with the object, and increases the contact area with the object.

  A robot hand 10 according to a first embodiment will be described with reference to FIGS. FIG. 1 is a side view of the robot hand according to the present embodiment. FIG. 2 is a side view of the first fingertip of the robot hand according to the first embodiment. FIG. 3 is a side view of the second fingertip of the robot hand according to the first embodiment. FIG. 4 is a side view of the fingertip showing the relationship between the contact angle and the contact area according to the present embodiment. FIG. 5 is a graph showing the relationship between the contact angle of the fingertip and the contact area according to the present embodiment.

  The robot hand 10 has four fingers (thumb A, index finger B, middle finger C, and ring finger D) to hold an object, and performs various operations on the object with the fingertip. In particular, the robot hand 10 has a finger having a first fingertip (final node) 11 and a second fingertip 12 that have both stability and skill when grasping an object.

  The first fingertip 11 is provided on the two opposing thumbs A and index finger B used when performing detailed operations such as holding and manipulating an object. The first fingertip 11 has an oval shape 11a whose side surface shape is represented by the formula (1) (see FIG. 2), and the surface shape of the portion other than the claw 11b and the base-side interference avoiding portion 11c necessary for the bending operation is the covering portion. Formed by. The interference avoiding portion 11c is cut at an angle of α / 2 ° because the maximum movable angle during the bending operation is α °.

  The second fingertip 12 is provided on two middle fingers C and ring fingers D used for stably holding an object. The second fingertip 12 has an elliptical shape 12a whose side surface shape is represented by the formula (2) (see FIG. 3), and the surface shape is formed by the covering portion in the same manner as the first fingertip 11.

  In the elliptical shape, the curvature is not constant like a perfect circle, and the curvature changes. In the equation representing the elliptical shape as shown in Equation (1), the smaller the multiplier (variable y, the multiplier of the constant b) of the rear term of the left side, the closer the elliptical shape is to a perfect circular shape, and the larger the multiplier, the rectangular shape. The shape is close to. The closer the shape is to a perfect circle, the less the change in the music part, so the curvature gradually changes. As it becomes closer to a rectangular shape, a corner portion is formed, so that the curvature changes from a small value to a large value (corner portion), and further changes from the large value to a small value.

  As shown in Expression (1), the elliptical shape 11a of the first fingertip 11 has a multiplier of a variable y and a constant b of 3, and is a shape closer to a perfect circle compared to the elliptical shape 12a. On the other hand, the elliptical shape 12a of the second fingertip 12 has a multiplier y of the variable y and the constant c as shown in Expression (2), and is a shape closer to a rectangular shape than the elliptical shape 11a. Therefore, in the first fingertip 11, the distal end portion 11 d has a larger curvature than the distal end portion 12 d of the second fingertip 12, and the central portion 11 e has a smaller curvature than the central portion 12 e of the second fingertip 12. On the other hand, in the second fingertip 12, the distal end portion 12 d has a smaller curvature than the distal end portion 11 d of the first fingertip 11, and the central portion 12 e has a larger curvature than the central portion 11 e of the first fingertip 11. The tip portions 11 d and 12 d are fingertip portions of the fingertips 11 and 12. The central portions 11e and 12e are portions closer to the middle node than the tip portions 11d and 12d of the fingertips 11 and 12. Note that, for the multipliers of the constants a, b, c, d and b, d, y in the expressions (1) and (2), the gripping skill by the first fingertip 11 and the gripping stability by the second fingertip 12 are determined. This is set in advance by experimentation.

  Since the side surfaces of the first fingertip 11 and the second fingertip 12 have an elliptical shape, as shown in FIG. 4, when the contact area θ with the object changes on the side surface, the contact area S changes. Moreover, the 1st fingertip 11 and the 2nd fingertip 12 have the elliptical shape 11a and the elliptical shape 12a which are different in a side surface shape, and a curvature structure differs. Thus, when the curvature configuration is different, the change in the contact area S is different with respect to the change in the contact angle θ. In addition, the contact angle θ increases as it comes into contact with the tip side of the fingertip (that is, as the fingertip is raised).

  As shown in FIG. 5, in the case of the first fingertip 11 indicated by reference sign K1, the change in the contact area S is relatively large with respect to the change in the contact angle θ. That is, the contact area S decreases as the tip part 11d comes into contact, and the contact area S increases as it comes into contact with the central part 11e. The contact area S varies greatly depending on which part comes into contact. On the other hand, in the case of the second fingertip 12 indicated by reference sign K2, the change in the contact area S is relatively small with respect to the change in the contact angle θ. In other words, the contact area S decreases as it comes into contact with the tip 12d side, and the contact area S increases as it comes into contact with the central part 12e. A relatively large contact area S can be obtained.

  Accordingly, when the object is gripped using the first fingertip 11, the contact area S can be freely changed by changing the contact angle θ, and accordingly, the frictional force (friction coefficient) according to the change of the contact area S. Can also be adjusted freely. On the other hand, when the object is gripped using the second fingertip 12, a relatively large contact area S that does not change so much regardless of how it is brought into contact is obtained, so that a sufficient friction force necessary for stable gripping can be obtained.

  The robot hand 10 configured as described above is suitable for performing detailed operations such as skillful holding and manipulation when gripping an object when the thumb A or index finger B provided with the first fingertip 11 is used. When the middle finger C or ring finger D provided with the second fingertip 12 is used, it is suitable for stably grasping (holding) an object.

  For example, when performing the work of lifting the dish on the table, first, using the thumb A or index finger B, lift the end of the dish with the tip 11d of the first fingertip 11 and sufficiently place the first fingertip 11 under the dish. Secure enough space for insertion. At this time, since the contact area S is small at the tip portion 11d and only a small frictional force acts, the first fingertip 11 is slid on the lower surface of the plate to move from the tip portion 11d to the center portion 11e, and the plate is moved at the center portion 11e. Hold. At this time, the contact area S is large in the central portion 11e, and a large frictional force is acting.

  When a complicated shape or an object that easily deforms is gripped, the necessary and sufficient contact area S (and hence the frictional force) can be obtained simply by applying the second fingertip 12 using the middle finger C or the ring finger D. The object can be stably held. In this case, it is not necessary to control the contact angle θ with high accuracy so that the object does not slide down.

  When igniting with a writer, the middle finger C and ring finger D are used to hold the writer firmly with the second fingertip 12. In this state, using the thumb A or the index finger B, the first fingertip 11 is slid with a small frictional force while turning the ignition part to ignite the fire.

  According to the robot hand 10, the first fingertip 11 and the second fingertip 12 having different curvature configurations are configured, and the two types of fingertips are used properly to achieve both stability and skill when gripping an object. be able to.

  A robot hand 20 according to a second embodiment will be described with reference to FIGS. 1, 6, and 7. FIG. 6 is a partially cutaway side view of the first fingertip of the robot hand according to the second embodiment. FIG. 7 is a partially cutaway side view of the second fingertip of the robot hand according to the second embodiment.

  In addition to the configuration of the robot hand 10 according to the first embodiment, the robot hand 20 is further characterized by the configuration of the fingertip covering portion. The robot hand 20 has a finger having a first fingertip 21 and a second fingertip 22 that have both stability and skill when grasping an object.

  The first fingertip 21 is provided on the two thumbs A and the index finger B, and has the same surface shape as the first fingertip 11 according to the first embodiment. The first fingertip 21 is provided with a covering portion 21f so as to cover the structure portion 23, and a surface shape is formed by the covering portion 21f. On the other hand, the second fingertip 22 is provided on the two middle fingers C and the ring finger D, and has the same surface shape as the second fingertip 12 according to the first embodiment. The second fingertip 22 is provided with a covering portion 22f so as to cover the structure portion 23, and a surface shape is formed by the covering portion 22f.

  The covering portions 21f and 22f have a thickness corresponding to the curvature of the surface shape of the fingertips 21 and 22, and the larger the curvature, the thicker the thickness. Therefore, since the curvature is smaller in the central portion 21e of the first fingertip 21 than in the central portion 22e of the second fingertip 22, the thickness t1 of the covering portion 21f is relatively thin. On the other hand, since the curvature of the central portion 22e of the second fingertip 22 is larger than that of the central portion 21e of the first fingertip 21, the thickness t2 (> t1) of the covering portion 22f is relatively thick.

  As the covering portions 21f and 22f are thinner, the force is more likely to be applied directly, so that the covering portions 21f and 22f are suitable for fine work requiring precision (for example, work for holding, changing, or manipulating small objects). On the other hand, the thicker the covering portion, the easier it is to deform along the shape of the object, which is suitable for firmly grasping an object. Therefore, the first fingertip 21 is more sophisticated when gripping an object than the second fingertip 22 due to the thin thickness of the covering portion 21f. On the other hand, the second fingertip 22 has higher stability when gripping an object than the first fingertip 21 due to the thick thickness of the covering portion 22f.

  According to this robot hand 20, the thickness and thickness of the covering portions 21 f and 22 f are set according to the curvatures of the surface shapes of the fingertips 21 and 22, thereby further improving stability and skill when gripping an object. Can do. In particular, in the case of the first fingertip 21, the thickness of the covering portion 21f becomes thin according to a small curvature, so that the object can be manipulated skillfully. Further, in the case of the second fingertip 22, the thickness of the covering portion 22f is increased according to a large curvature, so that the object can be stably grasped.

  As mentioned above, although embodiment which concerns on this invention was described, this invention is implemented in various forms, without being limited to the said embodiment.

  For example, in the present embodiment, the present invention is applied to the fingertip of each finger in a four-finger robot hand, but the present invention can be applied to various robot hands having a plurality of fingers such as three or five fingers.

  Further, in this embodiment, the curvature is the curvature of the tip of the fingertip in the sagittal plane, but the frontal plane (the surface when the fingertip is viewed from the front direction, the nail is on the upper side, and the belly of the finger is on the lower side. It is good also as a curvature of the front-end | tip part of the fingertip in the direction).

  In the first embodiment, two types of fingertips having different curvature configurations are used. However, three or more types of fingertips having different curvature configurations may be used. For example, it is good also as a structure which adds the 3rd fingertip in which the curvature of a front-end | tip part is still smaller than a 2nd fingertip, and the curvature of a center part is still larger.

  In addition, since only one thumb is opposed, it can be expected that the stability of the entire gripping that is opposite will increase by providing stability (or if the contact of the thumb with the fingertip is not stable). Therefore, there is a possibility that the stability of the entire grip may be impaired), and thus the thumb may be configured to be stable. As this configuration, for example, a robot hand provided with a plurality of opposing fingers and at least one fingertip shaped finger having a larger curvature than the other fingers, provided with a plurality of opposing fingers, the number of which is A robot hand in which at least one finger having a fingertip shape with a large curvature is arranged on the small side, and a fingertip having a curvature larger than the curvature of the fingertip of the other finger among the opposing thumb and other fingers There is a robot hand mounted on the thumb and a robot hand in which at least the thumb has a fingertip shape with a large curvature among a plurality of opposing fingers.

It is a side view of the robot hand concerning this embodiment. It is a side view of the 1st fingertip of the robot hand concerning a 1st embodiment. It is a side view of the 2nd fingertip of the robot hand concerning a 1st embodiment. It is a side view of the fingertip which shows the relationship between the contact angle and contact area which concern on this Embodiment. It is a graph which shows the relationship between the contact angle of the fingertip which concerns on this Embodiment, and a contact area. It is the side view which fractured | ruptured partially the 1st fingertip of the robot hand which concerns on 2nd Embodiment. It is the side view where the 2nd fingertip of the robot hand concerning a 2nd embodiment fractured partially.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,20 ... Robot hand, 11, 21 ... 1st fingertip, 11a ... Ellipse shape, 11b ... Nail, 11c ... Interference avoidance part, 11d ... Tip part, 11e, 21e ... Center part, 21f ... Cover part, 12, 22 ... 2nd fingertip, 12a ... Ellipse shape, 12d ... Tip, 12e, 22e ... Central part, 22f ... Covering part, 23 ... Structure part

Claims (4)

A robot hand having a plurality of fingers,
The plurality of fingers include a first finger and a second finger having different shapes of gripping portions of an object at a fingertip,
There are a plurality of the first fingers, the curvature of the tip of the fingertip is larger than that of the second finger, and the curvature of the central portion of the fingertip is smaller than that of the second finger . The degree of change of the contact area with respect to the contact angle is larger than that of the second finger,
Said second finger is located a plurality of, and the object when the curvature of the fingertip of the tip of curvature of the central portion of the first small and finger on the finger rather greater than the first finger to grip the object The degree of change of the contact area with respect to the contact angle is smaller than that of the first finger,
A robot hand characterized in that the plurality of first fingers are used when gripping an object that requires elaborateness, and the plurality of second fingers are used when gripping an object that requires stability .   The robot hand according to claim 1, wherein the finger is set to have a thickness based on a curvature of a grip portion of the object.   3. The robot hand according to claim 2, wherein when the curvature is large, the thickness is increased as compared with a case where the curvature is small.   The robot hand according to any one of claims 1 to 3, wherein the curvature is a curvature of a tip portion of a fingertip in a sagittal plane and / or a forehead plane.

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