JP2007222980A - Robot hand, and griping method with robot hand - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simultaneously grip two parts when small parts are gripped on the premise of a multi-finger griping type robot hand, in which two sets of two one-finger two-node type fingers are aligned in an overlaying direction relative to a hand body. <P>SOLUTION: One of fingers 2A, 2B and the remaining fingers 3A, 3B can grip separate parts W2, respectively. When the separate parts W2 are gripped by the fingers 2A, 2B and 3A, 3B, one of the fingers 2A, 2B grips the part W2, one of the fingers 2A, 2B gripping the part W2 is retreated in advance into a condition that a plane perpendicular to the overlaying direction of the fingers 2A, 2B and 3A, 3B is offset from the remaining fingers 3A, 3B prior to the griping action of the other fingers 3A, 3B. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a robot hand and a gripping method using a robot hand, and in particular, a so-called multi-purpose configuration in which a plurality of pairs of at least two joint-type fingers are arranged side by side in a superposition direction with respect to a hand body. The present invention relates to a finger type robot hand and a gripping method using a robot hand.

  For example, for picking multiple types of parts that are aligned on a parts shelf or parts box, two pairs of one-finger and two-joint-type fingers that are placed opposite to each other are placed side by side in the overlapping direction on the hand body. A general-purpose multi-finger type robot hand is used, and typical examples thereof are those described in Patent Documents 1 and 2, for example.

Then, in order to grip a plurality of types of parts from small parts to long or large parts, for example, two pairs of one-finger and two-joint type fingers arranged opposite to each other are arranged in the superposition direction with respect to the hand body. With a robot hand that is placed, when gripping small parts that are placed side by side, a pair of fingers is used to grip the part, while when gripping a long or large part, all two sets The finger is used to grip the part.
Japanese Patent Laid-Open No. 2002-264066 Japanese Patent Laid-Open No. 2004-50378

  If the same small parts are repeatedly gripped on the premise of using the robot hand as described above, only one set of fingers is used, so the remaining set of fingers is in a so-called idle state. Therefore, even if you try to grip the second part with a pair of remaining fingers to increase work efficiency, the first part you gripped will interfere with you and you will not be able to grip the second part. there were.

  The present invention has been made paying attention to such a problem, and at least two joint-type fingers per pair of two fingers arranged opposite to each other as described above are arranged side by side in the overlapping direction with respect to the hand body. On the premise of a so-called multi-finger type robot hand arranged, a robot hand and a gripping method are provided which can grip two or more parts at the same time, especially when gripping small parts.

  According to the first aspect of the present invention, a plurality of at least two joint-type fingers are arranged side by side in the overlapping direction with respect to the hand body, and two or more pairs of fingers arranged in a superposed state. While it is possible to grip a single gripping object by mutual cooperative operation, a part of the fingers and a remaining pair of fingers can grip separate gripping objects. It is assumed that the robot hand is.

  In addition, when gripping objects to be gripped by a plurality of pairs of fingers, if some of the fingers grip the object to be gripped, the gripping operation by the remaining pairs of fingers is preceded. The part of the fingers gripping the object to be gripped is retracted in advance so as to be offset with respect to the rest of the fingers in a plane orthogonal to the overlapping direction of the fingers. It is characterized by.

  In this case, as described in claim 3, it is sufficient that at least two pairs of one-finger and two-joint type fingers arranged opposite to each other are arranged side by side in the overlapping direction with respect to the hand body.

  The invention described in claim 4 captures the matter described in claim 1 as a gripping method, and two sets of opposing fingers are arranged side by side in a superposition direction with respect to the hand body. The plurality of pairs of fingers can be held in a superposed state so that a single object can be gripped by a mutual cooperative operation, while a part of the fingers and the rest of the fingers are separated from each other. It is assumed that this is a gripping method by a robot hand that can grip a gripping object.

  In addition, when gripping objects to be gripped by a plurality of pairs of fingers, if some of the fingers grip the object to be gripped, the gripping operation by the remaining pairs of fingers is preceded. Then, a part of the fingers holding the object to be grasped is retracted in advance so as to be offset with respect to the rest of the fingers in a plane perpendicular to the overlapping direction of the fingers.

  Therefore, according to the first and fourth aspects of the present invention, for example, a robot hand of a type in which two pairs of one-finger and two-joint-type fingers arranged opposite to each other are arranged side by side in the overlapping direction with respect to the hand body. In this case, when gripping separate gripping objects by two pairs of fingers, if one pair of fingers grips the gripping object, the gripping operation is performed prior to the gripping operation by the other pair of fingers. One set of fingers holding the object part is retracted in advance so as to be in an offset state with respect to the other set of fingers in a plane perpendicular to the overlapping direction of the fingers.

  By doing so, interference between the components is avoided, and the second component can be gripped without difficulty while the first gripping target is being gripped. As a result, for example, when picking parts that are aligned inside the parts box, multiple parts can be gripped with a single approach of the robot hand to the parts box, contributing to improved work efficiency. become able to.

  According to the first and fourth aspects of the present invention, when a plurality of sets of fingers are used effectively, a partial set of fingers and a remaining set of fingers are used to hold separate objects. If some of the fingers grasp the object to be grasped, prior to the grasping operation by the remaining pairs of fingers, some of the fingers that grasp the object to be grasped By retreating in advance so as to be in an offset state with respect to the remaining pairs of fingers in an orthogonal plane, interference between components is avoided, and the two gripping objects are in a state of gripping the first gripping object. As a result, it is possible to grip the part of the eye without any difficulty. For example, when picking a part that is aligned inside the part box from the part box, Can grip the plurality of parts approach operation, thereby improving work efficiency.

  FIG. 1 is a view showing a more specific embodiment of a robot hand according to the present invention, and shows an example of a general-purpose robot hand used for picking various parts arranged and stored in a parts box (not shown). FIG. 2A shows a front view thereof, and FIG. 2B shows a right side view thereof.

  As shown in FIGS. 1A and 1B, the robot hand 1 has two sets of two fingers 2A, 2B and 3A of a so-called two-finger grip type that are paired on the left and right sides by being opposed to each other. , 3B are arranged and supported on the hand body 4 at a predetermined distance so as to overlap each other, and the robot hand 1 as a whole has a total of four fingers 2A, 2B, 3A, 3B, and Each finger 2A, 2B, 3A, 3B has a root side joint 5a or 6a and a fingertip side joint 5b or 6b, and is of a so-called one-finger / two-joint type.

  As will be described later, each joint 5a, 5b, 6a, 6b incorporates independent servo motors as drive motors, and independent joint operations, that is, independent opening / closing of each finger component 7a, 7b. Operation is possible.

  According to the robot hand 1 configured as described above, it is commonly used for picking various parts from small parts to large parts or long parts as a gripping object, and the robot hand 1 with respect to a parts box is used. Assuming that one part is gripped by one approach operation, when gripping a large or long part W1 as shown in FIG. 2A, four fingers 2A, 2B, 3A , 3B, and in the case of the small component W2, as shown in FIG. 5B, the small component W2 is gripped using only one pair of fingers, for example, the fingers 3A, 3B. Thus, the remaining pair of fingers 2A and 2B are substantially idle and cannot be used effectively.

  Therefore, in order to effectively use the fingers 2A and 2B, for example, as shown in FIG. 3, the accessory parts W2 aligned and stored in the parts box 8 are separately provided for one finger 2A and 2B and the other finger 3A and 3B. Even if it is tried to grasp and take two so-called, the interval between the parts W2 and W2 stored in alignment and the interval between the fingers 2A, 3A and 2B and 3B do not always match, and the adjacent part W2 becomes an obstacle. So-called two cannot be taken.

  Therefore, in the present embodiment, particularly when the object to be grasped is a so-called accessory part W2, two pieces are to be obtained. As shown in FIGS. If 2B grips the small part W2, one pair of fingers 2A, 2B is temporarily retracted from the gripping completion position P1 indicated by the broken line to the retracted position P2 while maintaining the part gripping state, and in this state, as shown in FIG. The small part W2 is held by the other pair of fingers 3A and 3B.

  Here, FIGS. 6 and 7 show flock circuit diagrams of feedback control systems of the joints 5a, 5b and 6a, 6b in which the servo motors 10 are individually incorporated in FIG. 1, and the fingers 2A, 2B and 3A, 3B are shown. The joint operations of the base side joints 5a and 6a and the fingertip side joints 5b and 6b are controlled by the controller 9. The base joints 5a and 6a of the fingers 2A and 2B and 3A and 3B are provided with a rotary encoder 11 as a feedback element in addition to the servo motor 10, and form a feedback loop of position, speed and current respectively. Yes. Accordingly, each of the root side joints 5a and 6a can perform a joint operation by at least position feedback control (position control).

  On the other hand, the fingertip side joints 5b and 6b of the fingers 2A, 2B and 3A, 3B are similarly provided with a rotary encoder 11 as a feedback element in addition to the servo motor 10, and each has a position, speed and current feedback loop. In addition, the gain adjuster 12 or 13 and the switch (switch 1) 14 or switch (switch 2) 15 are provided. As a result, each of the fingertip side joints 5b and 6b is a so-called torque that uses the output of the gain adjuster 12 or 13 as a torque command value without depending on position feedback control in addition to at least joint motion by position feedback control (position control). The joint motion by control can be selected and switched.

  More specifically, as shown in FIG. 7, each of the gain adjusters 12 and 13 has a function of adjusting the gain of the input command value to be smaller than 1 (how much the gain is reduced). The output of the gain adjuster 12 at one fingertip side joint 5b is used as a torque command value at the time of torque control of the other fingertip side joint 6b, and the switch 15 on the other fingertip side joint 6b side. In addition, the output of the gain adjuster 13 in the other fingertip side joint 6b is input to the switch 14 on the one fingertip side joint 5b side as a torque command value at the time of torque control of the one fingertip side joint 5b. It has become. Each of the switches 14 and 15 is switched by a switching signal S1 or S2 from the controller 9, and is output from the controller 9 as a position command value of the corresponding fingertip side joint 5b or 6b. Selectively servo between the command value at the time of position feedback control and the torque command value at the time of torque control which is the output of the gain adjuster 13 or 12 attached to the opposite fingertip side joint 6b or 5b. It can be applied to the motor 10 side. Table 1 summarizes the combinations of the states of the switches 14 and 15 and the control forms (whether position feedback control (position control) or torque control) of the fingertip side joints 5b and 6b.

  Here, when the output of the gain adjusters 12 and 13 is selected as a torque command value in each of the switches 14 and 15 in FIG. The speed feedback loop is based on the fact that only the current feedback loop works, with no function.

  Therefore, according to the robot hand 1 configured in this way, regardless of whether it is a long or large part W1 or a small part W2, as shown in FIG. At the time of this approach operation, as shown in FIG. 8A, both the base side joints 5a and 6a and the fingertip side joints 5b and 6b are performed under position feedback control. That is, the base side joints 5a and 6a perform position control under the feedback loop of FIG. 6, and the fingertip side joints 5b and 6b switch the switches 14 and 15 shown in FIG. Position control of 5b and 6b is performed (pattern 1 in Table 1).

  On the other hand, at the time of the actual gripping operation shown in FIG. 8B following the approach operation, the base side joints 5a and 6a perform position feedback control based on FIG. 6, while the fingertip side joints 5b and 6b show FIG. For example, the small component W2 to be gripped is gripped by switching the switches 14 and 15 to the B contact side and performing the torque control of the joints 5b and 6b in synchronization (pattern 4 in Table 1).

  When the respective switches 14 and 15 in FIG. 7 are switched to the B contact side to perform torque control of the joints 5b and 6b, the torque command value is gained by the gain adjuster 12 or 13 as described above. Is previously adjusted to be smaller than 1, the torque value is smaller than that at the time of position feedback control. Further, as is apparent from FIG. 7, each fingertip side joint 5b, 6b operates with the output of the gain adjuster 13 or 12 attached to the opposite fingertip side joint 6b or 5b as a torque command value. Therefore, both the fingertip side joints 5b and 6b operate synchronously, and each fingertip side joint 5b and 6b continues to operate as long as the opposite fingertip side joint operates, and is based on the above torque control. For example, the accessory part W2 is pressed with a constant force. Then, when the movements of the fingertip side joints 5b and 6b cease, the gripping of the accessory parts W2 is completed (this can be confirmed by monitoring the output of the rotary encoder 11 attached to each servo motor 10), and thereafter Will maintain its gripping state.

  On the other hand, when two so-called two small parts W2 are taken in the form as shown in FIGS. 4 and 5, only the pair of fingers 2A and 2B are first operated, and the part W2 is exactly the same as in FIG. Grip. Then, if the pair of fingers 2A and 2B grips the accessory part W2, the pair of fingers 2A and 2B is retracted to the retracted position P2 as shown by the broken line in FIG. In this retracting operation, the root side joints 5a and 6a are set to the position feedback control of FIG. 6, and one fingertip side joint 6b is also switched to the position feedback control as shown in FIG. Only 5b is switched to the torque control as shown in FIG. 7 (pattern 3 in Table 1), and the pair of fingers 2A and 2B already holding the accessory part W2 are moved to the retracted position P2. That is, prior to the gripping operation of the component W2 by the fingers 3A and 3b, the pair of fingers 2A and 2B gripping the component W2 is in a plane perpendicular to the overlapping direction of the fingers 2A and 2B and 3A and 3B. It is assumed that the other pair of fingers 3A and 3B is retracted in advance so as to be in an offset state.

  More specifically, when the pair of fingers 2A and 2B that have already grasped the accessory part W2 are moved to the retracted position P2 in FIG. When the other joints 5a, 6a, 5b are operated by position feedback control, particularly the other fingertip side joint 6b is formed between the finger component 7 of the finger 2B already pressed against the part W2 and the part W2. In the one fingertip side joint 2A that has been position-controlled so as to maintain a constant angular posture so that the relative positional relationship does not change, and that is switched to torque control, the gain on the fingertip side joint 6b is shown in FIG. Since the output of the adjuster 13 is a torque command value, the finger component 7 is pressed against the component W2 with a constant force as long as the fingertip side joint 6b is operating. Will be that, thus can move a set of finger 2A to the retracted position P2 is outside the interference area while reliably grasping the small parts W2, the 2B.

  As shown in FIGS. 4 and 5, when one pair of fingers 2A, 2B has moved to the retracted position P2, instead move the other pair of fingers 3A, 3B to a position where the adjacent part W2 can be gripped. Then, the second component W2 is gripped in the same procedure as in FIG. When gripping the second component W2, one set of fingers 2A, 2B that has already gripped the first component W2 is in the retracted position P2, so this other set of fingers 3A , 3B can smoothly grip the second component W2 without interfering with the first component W2, the component box 8, and the like.

  Thus, according to this embodiment, for example, when picking small parts W2 aligned and stored in the parts box 8, two so-called two parts W2 are picked up by one approach operation of the robot hand 1 with respect to the parts box 8. Thus, picking work efficiency is greatly improved.

  Here, in the above embodiment, an example is shown in which the servo motor 10 that is the drive source of each joint 5a, 5b, 6a, 6b is built in the joint 5a, 5b, 6a, 6b. Each servo motor 10 is built in the hand body 4 and is a type of robot hand that is operated by transmitting power from each servo motor 10 to each joint 5a, 5b, 6a, 6b via a winding transmission means or the like. Needless to say, the present invention can also be applied.

  The present invention can also be applied to a robot hand using fingers that have three or more joints per finger.

It is a figure which shows an example of the robot hand which concerns on this invention, (A) is the front view, (B) is a word side view of the figure (A). (A) is explanatory drawing which shows the state which hold | grips a long or large component with the robot hand shown in FIG. 1, (B) is explanatory drawing which shows the state which hold | gripped the accessory component similarly. Explanatory drawing which shows the interference state at the time of taking two so-called small parts. Explanatory drawing which shows the interference avoidance state at the time of taking two so-called small parts. Front explanatory drawing of FIG. 6 is a block circuit diagram of the feedback control system for the proximal joint in FIGS. The block circuit diagram of the feedback control system of the fingertip side joint in FIGS. (A) is explanatory drawing at the time of approach of the robot hand with respect to components, (B) is explanatory drawing at the time of the actual holding | grip following the said approach operation | movement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Robot hand 2A, 2B ... Finger 3A, 3B ... Finger 4 ... Hand main body 5a, 6a ... Base side joint 5b, 6b ... Fingertip side joint 7a, 7b ... Finger component 9 ... Controller 10 ... Servo motor 12, 13 ... Gain adjusters 14, 15 ... Switch P2 ... Retraction position W1, W2 ... Part (object to be gripped)

Claims (4)

A pair of at least two joint-type fingers per one pair of fingers arranged opposite to each other are arranged side by side in the overlapping direction with respect to the hand body,
While these multiple pairs of fingers can be held in a superposed state and can hold a single object by mutual cooperation,
Some sets of fingers and the remaining sets of fingers can each hold a separate object to be gripped,
When gripping separate gripping objects with a plurality of pairs of fingers, if some pairs of fingers grip the gripping object, the gripping object precedes the gripping operation by the remaining pairs of fingers. It is characterized in that a part of the fingers holding the part is retracted in advance so as to be offset with respect to the rest of the fingers in a plane perpendicular to the overlapping direction of the fingers. Robot hand.   The joint of each finger is provided with an independent drive motor, and at least the joint on the most fingertip side can be selectively switched between joint operation by position control and joint operation by torque control. The robot hand according to 1.   The robot hand according to claim 1 or 2, wherein two sets of one-finger and two-joint type fingers arranged opposite to each other are arranged side by side in the overlapping direction with respect to the hand body. A set of two fingers arranged opposite each other are arranged side by side in the polymerization direction with respect to the hand body,
While these multiple pairs of fingers can be held in a superposed state and can hold a single object by mutual cooperation,
A gripping method by a robot hand in which a part of fingers and a remaining pair of fingers can grip separate objects to be grasped,
When gripping separate gripping objects with a plurality of pairs of fingers, if some pairs of fingers grip the gripping object, the gripping object precedes the gripping operation by the remaining pairs of fingers. A method of gripping with a robot hand, wherein a part of fingers holding a part is retracted in advance so that the fingers are offset in a plane perpendicular to the overlapping direction of the fingers. .

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