JP2019089179A - Holding system and method for controlling the same - Google Patents

Abstract

To provide a holding system comprising a hand mechanism for holding an object with a plurality of finger parts, which can suppress tact time from getting longer unnecessarily.SOLUTION: Search-operation control is performed in a state where a form of a hand mechanism is set to a form for search in which a position in a predetermined direction of a predetermined contact site in a finger part for sub-search is positioned closer to a predetermined target position by a predetermined distance shorter than a dimension in a predetermined direction of an object in comparison with a predetermined contact site in the finger part for search and a position in a direction orthogonal to the predetermined direction of the predetermined contact site in the finger part for sub-search is positioned away from a region in which the object is assumed to exist. Before contacting of the predetermined contact site in the finger part for search with the object is detected, when contacting of the predetermined contact site in the finger part for sub-search with the object is detected, the search operation control is stopped immediately.SELECTED DRAWING: Figure 13

Description

  The present invention relates to a gripping system provided with a hand mechanism that grips an object with a plurality of fingers and a control method thereof.

  BACKGROUND Conventionally, a hand mechanism attached to a robot arm or the like and gripping an object with a plurality of finger parts has been developed. For example, Patent Document 1 discloses a robot apparatus provided with a hand mechanism (multi-finger hand unit) having a plurality of finger portions, and a robot arm having the hand mechanism attached to the tip. In the robot apparatus described in Patent Document 1, force sensors are provided on each finger of the hand mechanism. The force sensor detects the contact position between the finger and the object. The robot apparatus also includes a visual sensor that captures image data including an object. And the positional information on a target object is acquired based on the image data imaged by the visual sensor. Furthermore, the position information of the object acquired from the image data is corrected based on the information of the contact position detected by the force sensor.

Patent No. 5505138 gazette

  As in the above-mentioned prior art, before gripping the object by the hand mechanism, an operation (hereinafter sometimes referred to as a "searching operation") is performed to bring the finger of the hand mechanism into contact with the object; Deriving the contact position makes it possible to grasp the position of the object with higher accuracy. It is very preferable to grasp the position of the object with high accuracy as described above in order to improve the stability of the gripping of the object by the hand mechanism.

  However, when the above search operation is performed in a case where an error is included in position information acquired from image data or the like, or when an object is moved after acquisition of image data or the like, when the above-described search operation is performed, the finger unit May not come in contact with the object. In such a case, if the search operation is continued until the finger contacts an object other than the object (for example, the floor surface on which the object is placed), the tact time becomes unnecessarily long. It causes a problem.

  The present invention has been made in view of the above problems, and in a gripping system provided with a hand mechanism that grips an object with a plurality of fingers, suppressing unnecessary increase in tact time To provide technology that can

A gripping system according to the present invention comprises a hand mechanism having a plurality of finger portions and gripping an object by the plurality of finger portions, an arm mechanism for changing the position of the hand mechanism, and the plurality of the hand mechanisms. A contact detection unit provided on at least two predetermined finger portions of the finger portions and detecting that a predetermined contact site in each of the predetermined two finger portions is in contact with the object; Prepare. When the control unit grips the object by the hand mechanism, it is assumed that the predetermined contact site and the object exist in the search finger portion which is one finger portion of the predetermined two finger portions. To control the hand mechanism and / or the arm mechanism so as to move the predetermined contact portion of the search finger toward the predetermined target position from a state where the predetermined position and the predetermined position are separated in the predetermined direction By performing the search operation control, the contact position when the contact of the predetermined contact site on the search finger with the object is detected by the contact detection unit of the search finger is derived. Subsequently, the control unit controls the arm mechanism and / or the hand mechanism based on the contact position derived in the search operation control to move the hand mechanism to a predetermined grippable position. The object is gripped by the hand mechanism. Here, when the search operation control is performed, the control unit determines the position in the predetermined direction of the predetermined contact portion in the sub search finger portion which is the other finger portion of the predetermined two finger portions. The hand mechanism is controlled so as to be closer to the predetermined target position by a predetermined distance shorter than the dimension of the target in the predetermined direction, as compared to the predetermined contact portion of the search finger portion. In the state, the search operation control is performed. Then, before the contact detection unit of the search finger detects a contact of the predetermined contact region on the search finger, an object of the predetermined contact region on the sub search finger When a touch on the sub-search finger is detected by the touch detection unit, the control unit cancels the search operation control at that time.

  According to the present invention, it is possible to suppress unnecessary increase in tact time in a gripping system provided with a hand mechanism that grips an object with a plurality of finger portions.

It is a figure showing a schematic structure of a robot arm concerning an example. It is a perspective view of a hand mechanism concerning an example. It is a top view of the hand mechanism concerning an example. It is a side view of a finger part of a hand mechanism concerning an example. It is the figure which looked at the front-end | tip part side of the finger part of the hand mechanism which concerns on an Example from the direction of arrow A of FIG. It is a figure which shows the movable range of the 2nd joint part in the finger part of the hand mechanism which concerns on an Example. It is a figure which shows the movable range of the 1st joint part in the finger part of the hand mechanism which concerns on an Example. It is a 1st figure which shows arrangement | positioning of the pressure sensor in the 1st link part of the finger part of the hand mechanism which concerns on an Example. It is a 2nd figure which shows arrangement | positioning of the pressure sensor in the 1st link part of the finger part of the hand mechanism which concerns on an Example. It is a block diagram showing each functional part contained in an arm control device concerning an example, and a hand control device. It is a figure which shows the position in the orthogonal | vertical direction of the finger part for search when the search operation control in a present Example is performed, and the finger part for subsearches. It is a figure which shows the mode of a hand mechanism when the search operation control of a present Example is performed in the state in which an actual target object exists in an assumption position. It is a 1st figure which shows the mode of a hand mechanism when the search operation control of a present Example is performed in the state in which an actual target object does not exist in an assumption position. It is a 2nd figure which shows the mode of a hand mechanism when the search operation control of a present Example is performed in the state in which an actual target object does not exist in an assumption position. It is a figure which shows the position in the horizontal direction of the finger part for search when the search operation control in a present Example is performed, and the finger part for subsearches. It is a flowchart which shows the flow of the search operation control which concerns on an Example.

In the gripping system according to the present invention, various types of information such as the size, shape, and position information of the object to be gripped by the hand mechanism are obtained in advance. These various information are input by the user and
It is acquired based on the image etc. which were imaged by the visual sensor. Further, among a plurality of finger portions in the hand mechanism, at least two finger portions of the search finger portion and the sub search finger portion, a predetermined contact portion in each of the two finger portions contacts the object A contact detection unit is provided to detect that the user has made an event.

  When grasping an object by the hand mechanism, first, the control section starts the search finger from a state in which a predetermined contact site on the search finger and a position where the object is assumed to be present are separated in a predetermined direction. By performing search operation control for controlling the hand mechanism and / or the arm mechanism so that a predetermined contact site on the head approaches a predetermined target position, the target of the predetermined contact site on the search finger portion The contact position is derived when the contact is detected by the contact detection unit of the search finger. Then, based on the contact position derived in the search operation control, the control unit controls the arm mechanism and / or the hand mechanism to move the hand mechanism to a predetermined grippable position by the hand mechanism. The object is gripped (gripping operation control). Here, the predetermined target position is a position determined based on position information of the object, and is a position determined on the assumption that the object is present at the position corresponding to the above-described position information. Further, the predetermined gripping position is a position where stable gripping of the target can be realized by sandwiching the target with a plurality of fingers when the hand mechanism is positioned at the predetermined gripping position. It is determined based on the size and shape of the object.

  By the way, in the case where the position information of the target obtained in advance includes an error, or in the case where the target is moved after the position information of the target is obtained, the above-mentioned position information There may be no actual object at the position corresponding to. If search operation control is performed in such a situation, the search operation control may be continued until a predetermined contact site on the search finger contacts an object other than the target, and the tact time is not necessary. It can be long.

  On the other hand, in the gripping system according to the present invention, the position in the predetermined direction of the predetermined contact portion in the sub search finger portion is an object in the predetermined direction compared to the predetermined contact portion in the search finger portion. The search operation control is performed in a state where the hand mechanism is controlled so as to be close to the predetermined target position by a predetermined distance shorter than the dimension of.

  Here, when the above-described search operation control is performed, if the actual target does not exist at the position corresponding to the position information acquired in advance, the predetermined contact portion in the search finger portion is the object ( Before contact with an object (other than the object), a predetermined contact site on the subsearch finger portion comes in contact with the object (object or an object other than the object). Therefore, in the gripping system according to the present invention, the predetermined contact on the sub search finger is detected before the contact between the predetermined contact portion on the search finger and the object is detected by the contact detection unit on the search finger. When the contact between the part and the object is detected by the contact detection unit of the sub search finger, the search operation control is stopped at that time. In that case, the search operation control is not unnecessarily continued until the predetermined contact portion in the search finger portion contacts an object other than the target. As a result, it can be suppressed that the tact time becomes unnecessarily long.

<Example>
Hereinafter, specific embodiments of the present invention will be described based on the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the invention to them unless otherwise specified.

Here, a case where the hand mechanism and the gripping system according to the present invention are applied to a robot arm will be described. FIG. 1 is a view showing a schematic configuration of a robot arm according to the present embodiment. The robot arm 1 includes a hand mechanism 2, an arm mechanism 3, and a pedestal 4. The hand mechanism 2 is attached to one end of the arm mechanism 3. Further, the other end of the arm mechanism 3 is attached to the pedestal 4. The hand mechanism 2 includes a base portion 20 connected to the arm mechanism 3 and a plurality of finger portions 21 (four finger portions 21 in the example shown in FIG. 1) movably supported by the base portion 20. Is equipped. The detailed configuration of the hand mechanism 2 will be described later.

<Arm mechanism>
The arm mechanism 3 includes a first arm link 31, a second arm link 32, a third arm link 33, a fourth arm link 34, a fifth arm link 35, and a connection member 36. The base portion 20 of the hand mechanism 2 is connected to a first joint portion 30 a formed on one end side of the first arm link portion 31 of the arm mechanism 3. The first joint portion 30 a is provided with a motor (not shown) for rotating the hand mechanism 2 with respect to the first arm link portion 31 around the axis of the first arm link portion 31. The other end side of the first arm link portion 31 is connected to one end side of the second arm link portion 32 by the second joint portion 30 b. The first arm link portion 31 and the second arm link portion 32 are connected so that their central axes intersect perpendicularly. A motor for rotating the first arm link 31 relative to the second arm link 32 in the second joint 30b about the axis of the second arm link 32 about the other end. (Not shown) is provided. Further, the other end side of the second arm link portion 32 is connected to one end side of the third arm link portion 33 at the third joint portion 30 c. The third joint 30 c is provided with a motor (not shown) for rotating the second arm link 32 relative to the third arm link 33.

  Similarly, the other end of the third arm link 33 is connected to one end of the fourth arm link 34 at the fourth joint 30 d. Further, the other end side of the fourth arm link portion 34 is connected to the fifth arm link portion 35 at the fifth joint portion 30 e. The fourth joint unit 30 d is provided with a motor (not shown) for rotating the third arm link unit 33 relative to the fourth arm link unit 34. Further, the fifth joint unit 30 e is provided with a motor (not shown) for relatively rotating the fourth arm link unit 34 with respect to the fifth arm link unit 35. Furthermore, the fifth arm link portion 35 is connected to the connection member 36 disposed vertically from the pedestal portion 4 at the sixth joint portion 30 f. The fifth arm link portion 35 and the connection member 36 are connected such that their central axes are coaxial. The sixth joint unit 30 f is provided with a motor (not shown) for rotating the fifth arm link unit 35 around the axes of the fifth arm link unit 35 and the connection member 36. By configuring the arm mechanism 3 in such a configuration, for example, the arm mechanism 3 can be a mechanism having six degrees of freedom.

<Hand mechanism>
Next, the configuration of the hand mechanism 2 will be described based on FIGS. 2 to 9. FIG. 2 is a perspective view of the hand mechanism 2. FIG. 3 is a top view of the hand mechanism 2. In addition, in FIG. 3, the arrow indicates the rotation movable range of each finger portion 21. As shown in FIGS. 2 and 3, in the hand mechanism 2, the four fingers 21 of the base portion 20 are centered on the axis of the hand mechanism 2 in the longitudinal direction (direction perpendicular to the paper in FIG. 3). On the circumference, they are arranged at equal angular intervals (that is, 90 degrees). The four fingers 21 all have the same structure and the same length. However, the operation of each finger unit 21 is controlled independently.

  4 to 9 are diagrams for describing the configuration of the finger unit 21 of the hand mechanism 2. FIG. 4 is a side view of the finger 21. As shown in FIG. In addition, in FIG. 4, it describes in the state through which the base part 20 was permeate | transmitted. 5 is a view of the tip end side of the finger 21 as viewed in the direction of arrow A in FIG. 4 and 5, the second finger link portion 212 of the finger portion 21 described later is described in a partially transmitted state, and the internal structure of the second finger link portion 212 is also shown. There is.

  As shown in FIGS. 2 and 4, each finger 21 has a first finger link 211, a second finger link 212, and a proximal end 213. In addition, between the first finger link portion 211 and the second finger link portion 212, a first joint portion 22 formed so as to be bendable and extendable is provided. Furthermore, between the second finger link portion 212 and the proximal end portion 213, a second joint portion 23 formed so as to be bendable and extendable is provided. The proximal end 213 of the finger 21 is connected to the base 20 so as to be rotatable around an axis in the longitudinal direction of the finger 21 (the direction perpendicular to the paper surface in FIG. 3).

  Further, as shown in FIG. 4, the base unit 20 incorporates a second motor 52 and a third motor 53. The second motor 52 is a motor for bending and extending the second joint portion 23, as shown in FIG. The third motor 53 is a motor for rotationally driving the entire finger portion 21 in the range indicated by the arrow in FIG. Further, as shown in FIG. 5, the first motor 51 is incorporated in the second finger link portion 212. The first motor 51 is a motor for bending and extending the first joint portion 22 as shown in FIG.

  Next, as shown in FIG. 2, FIG. 4 and FIG. 5, the pressure sensor 70 is provided on the outer wall surface of the distal end side portion (the distal end side portion of the first finger link portion 211) in each finger portion 21. It is attached. Specifically, as shown in FIGS. 8 and 9, an outer wall surface of the first finger link portion 211 in the bending direction of the first joint portion 22 (hereinafter, may be referred to as a “flexing side wall surface”). Four pressure sensors 700, 701, 702, 703 (hereinafter referred to as "pressure sensor 70" collectively from 215 to an outer wall surface in the extension direction (hereinafter sometimes referred to as "extension sidewall surface") 216 In some cases) are arranged in series along the longitudinal direction of the first finger link portion 211. In the example shown in FIGS. 8 and 9, one pressure-sensitive sensor 700 is disposed on the extension side wall surface 216, and the remaining three pressure-sensitive sensors 701, 702, 703 are from the distal side to the proximal side of the bending side wall surface 215. For the purpose, they are arranged in the longitudinal direction. In addition, the arrangement method of the pressure sensor 70 is not limited to the method of arranging in series along the longitudinal direction of the first finger link portion 211, and is arranged in series along the lateral direction of the first finger link portion 211 It may be disposed along the oblique direction with respect to the longitudinal direction or the lateral direction of the first finger link portion 211. In the example shown in FIGS. 8 and 9, four pressure-sensitive sensors 700, 701, 702, 703 are arranged in a row, but four or more pressure-sensitive sensors may be arranged in two or more rows. Or, four or more pressure sensors may be arranged in a staggered manner. Also, the number of pressure sensors disposed on the extension side wall surface 216 is not limited to one, and two or more pressure sensors may be disposed on the extension side wall surface 216. Similarly, the number of pressure-sensitive sensors disposed on the bending side wall surface 215 is not limited to three, and may be two or four or more. In short, the number and the position of the pressure-sensitive sensors arranged in the first finger link portion depend on the position, the range, etc. where the object can be in contact at the first finger link portion when the hand mechanism grips the object. It may be determined appropriately. The pressure sensor 70 is a sensor that detects an external force (pressure) acting on the first finger link portion 211. As such a pressure-sensitive sensor 70, any known pressure-sensitive sensor such as a piezoelectric pressure-sensitive sensor, a strain gauge-type pressure-sensitive sensor, or a capacitance-type pressure-sensitive sensor may be used. Good. The four pressure sensors 700, 701, 702, and 703 described above may be covered with a flexible sensor cover formed of polyolefin or the like. In the examples shown in FIGS. 8 and 9, the pressure sensor 70 is formed in a rectangular shape, but is not limited to a rectangular shape, and is appropriately changed according to the shape of the first finger link portion 211 and the like. Just do it.

<Pedestal>
Next, the configurations of the arm control device 42 and the hand control device 43 built in the pedestal portion 4 will be described based on FIG. The arm control device 42 is a control device for controlling the arm mechanism 3 of the robot arm 1. The hand control device 43 is a control device for controlling the hand mechanism 2 of the robot arm 1. FIG. 10 is a block diagram showing each functional unit included in the arm control device 42 and the hand control device 43.

  The arm control device 42 includes a plurality of drivers for generating drive signals for driving the motors provided at the joints of the arm mechanism 3 so that the drive signals from the drivers are supplied to the corresponding motors. Configured The arm control device 42 also includes a computer having an arithmetic processing unit and a memory. The arm control device 42 includes an arm control unit 420 and a motor state quantity acquisition unit 421 as functional units. These functional units are formed by executing a predetermined control program in a computer included in the arm control device 42.

  The arm control unit 420 is a functional unit possessed by the hand control device 43, and an object information acquired by an object information acquiring unit 430 described later and a positional information correction unit 435 described later being a functional unit possessed by the hand control device 43. By supplying a drive signal from each driver based on the determined position information of the target 10, the motor provided at each joint 30a, 30b, 30c, 30d, 30e, 30f of the arm mechanism 3 is controlled. Then, the arm control unit 420 moves the arm mechanism 3 by controlling each motor, thereby moving, for example, the hand mechanism 2 to a predetermined grippable position suitable for gripping the object. In addition, the motor provided in each joint 30a, 30b, 30c, 30d, 30e, 30f of the arm mechanism 3 detects a state quantity (rotational position or rotational speed, etc. of the rotation shaft of the motor) related to each rotational state An encoder (not shown) is provided. Then, the state quantity of each motor detected by the encoder of each motor is input to the motor state quantity acquisition unit 421 of the arm control device 42. Then, based on the state amount of each motor input to the motor state amount acquisition unit 421, the arm control unit 420 servo-controls each motor so that the hand mechanism 2 moves to a predetermined grippable position, for example.

  Further, the hand control device 43 includes a plurality of drivers for generating drive signals for driving the respective motors provided in the hand mechanism 2 so that the drive signals from the respective drivers can be supplied to the corresponding motors. Configured The hand control device 43 also includes a computer having an arithmetic processing unit and a memory. The hand control device 43 has an object information acquisition unit 430, a hand control unit 431, a motor state quantity acquisition unit 432, a sensor information acquisition unit 433, a contact position derivation unit 434, and a position information correction unit 435 as functional units. doing. These functional units are formed by executing a predetermined control program in a computer included in the hand control device 43.

  The object information acquisition unit 430 acquires object information which is information on an object to be gripped by the hand mechanism 2. Here, the object information is information on the shape, size, and position of the object, and environmental information around the object (information on objects other than the object present around the object, for example, And the information on the shape of the container in which the object is stored, the arrangement of the object in the container, and the like. The target object information acquisition unit 430 may acquire target object information input by the user. Moreover, when the visual sensor which images the image containing a target object is provided, the target object information acquisition part 430 may acquire target object information from the image imaged by this visual sensor.

In addition, the hand control unit 431 supplies a drive signal from each driver based on the object information acquired by the object information acquisition unit 430 and the position information of the object 10 determined by the position information correction unit 435. The first motor 51, the second motor 52, and the third motor 53 that drive the fingers 21 of the hand mechanism 2 are controlled. For example, the hand control unit 431 controls each of the first and second hand mechanisms 2 to hold an object by the hand mechanism 2 moved to a predetermined grippable position by the arm control unit 420 controlling the arm mechanism 3. The motor 51, each second motor 52, and each third motor 53 are controlled. Further, state quantities (rotational position, rotational speed, etc. of the rotation shaft of the motor) regarding the respective rotational states are detected in each of the first motor 51, the second motor 52, and the third motor 53 of the hand mechanism 2. An encoder (not shown) is provided. Then, the state quantities of the motors 51, 52, 53 detected by the encoders of the motors 51, 52, 53 are input to the motor state quantity acquisition unit 432 of the hand control device 43. Then, based on the state quantities of the motors 51, 52, 53 input to the motor state quantity acquisition part 432, the hand control part 431 holds the fingers, for example, so as to hold the object with a plurality of finger parts 21. The servo control of each motor 51, 52, 53 in the unit 21 is performed.

  Furthermore, the hand control device 43 has a sensor information acquisition unit 433. The sensor information acquisition unit 433 receives the detection value of the pressure sensor 70 provided on the first finger link unit 211 of each finger unit 21 of the hand mechanism 2. Then, when the pressure sensor 70 detects that the finger unit 21 touches the object, the hand control unit 431 detects the motors 51, 52, and 53 in the finger unit 21 based on the detection signal. Can also be controlled. Further, when the pressure sensors 70 detect the contact of each finger 21 with the object, the contact position deriving unit 434 derives the contact position.

<Search operation control>
Here, in the robot arm 1 according to the present embodiment, the target object information acquisition unit 430 which is a functional unit included in the hand control device 43 acquires target object information including position information of the target object. However, there is a possibility that the position information of the object acquired by the object information acquisition unit 430 may include some degree of error. For example, when position information of an object is acquired from an image including an object imaged by a visual sensor, an error due to imaging performance of the visual sensor is included in the position information of the object. However, in order to stably hold the object by the hand mechanism 2 of the robot arm 1, it is possible to control the arm mechanism 3 and / or the hand mechanism 2 after grasping the position information of the object with high accuracy. desired.

  Therefore, in the robot arm 1 according to the present embodiment, before controlling the arm mechanism 3 and / or the hand mechanism 2 to grip the object, the positional information of the object in the predetermined direction is highly accurate as a preparation step. Search operation control is performed for the purpose of grasping in Hereinafter, search operation control according to the present embodiment will be described based on FIGS. 11A to 11D. The search operation control is realized by the arm control device 42 controlling the arm mechanism 3 and the hand control device 43 controlling the hand mechanism 2.

  Hereinafter, each finger 21 of the hand mechanism 2 will be referred to as a first finger 21A, a second finger 21B, a third finger 21C, and a fourth finger 21D, respectively. Further, in the search operation control, a predetermined finger portion (corresponding to the “search finger portion” according to the present invention) of the four finger portions 21 of the hand mechanism 2 is brought into contact with the object. 11A to 11D show the operation in the case where the search finger to be brought into contact with the object 10 is the first finger 21A. 11A to 11D, for convenience, only the first finger portion 21A and the third finger portion 21C in the hand mechanism 2 are illustrated, and the second finger portion 21B and the fourth finger portion 21D are illustrated. Is omitted. 11A to 11D show an operation in the case where it is intended to grasp positional information of the object 10 in the vertical direction (vertical direction in FIGS. 11A to 11C).

In the search operation control, the hand mechanism 2 is moved in the direction of the outlined arrow (that is, in the downward direction in FIG. 11A) in a state where the form of the hand mechanism 2 is controlled to the search form as shown in FIG. Thus, the hand mechanism 2 is brought close to the area where the object 10 is present. At that time, the tip end portion of the first finger portion 21A (the portion where the pressure sensor 70 is disposed in the first finger link portion 211A of the first finger portion 21A) is at a predetermined target position (indicated by a black circle in FIG. 11A) ) Each joint 30a, 30b, 30c, 30d of the arm mechanism 3 so as to move toward Tp.
, 30e, 30f, and each first motor 51, each second motor 52, and each third motor 53 for driving each joint of each finger 21 of the hand mechanism 2 is an arm, respectively. Servo control is performed by the controller 42 and the hand controller 43.

  Here, the “search form” in the present embodiment is the first finger link (the first finger link of the third finger 21C) of the third finger 21C (corresponding to the “subsearch finger according to the present invention”). The position in the vertical direction of the portion where the pressure sensor 70 is disposed in the portion 211C is a position closer to the predetermined target position Tp by the predetermined distance dhf than the tip portion of the first finger portion 21A, as shown in FIG. That is, the position is lower than the tip end portion of the first finger portion 21A by the predetermined distance dhf. The above-mentioned predetermined distance dhf is as long as possible in a range shorter than the dimension (that is, the height of the object 10) ho of the object 10 in the vertical direction. Further, in the “search mode” in the present embodiment, the position of the tip end portion of the first finger portion 21A in the horizontal direction is the horizontal direction of the predetermined target position Tp, as indicated by “Ra” in FIG. It is assumed that the position is determined to overlap with the position ("Rtp" in FIG. 12). Furthermore, in the “search mode” in the present embodiment, the position of the tip of the third finger 21C in the horizontal direction is acquired by the object information acquisition unit 430, as indicated by “Rc” in FIG. The object 10 is located at a position corresponding to the position information of the object 10 included in the object information (the position 10 ′ indicated by the dashed dotted line in FIG. 11A and hereinafter referred to as “the assumed position 10 ′”). When it is assumed that the object 10 is assumed to be present, it is assumed that the object 10 is defined at a position deviated from the region ("R10 '" in FIG. 12) occupied in the horizontal direction. The “predetermined target position Tp” referred to here is a position that is the inside of the object 10 when it is assumed that the object 10 exists in the above assumed position 10 ′, and the above object information Are determined based on the position information of the object 10 included in Further, in the above-described search mode, the positions of the tip of the second finger 21B and the tip of the fourth finger 21D in the vertical direction are further from the predetermined target position Tp than the tip of the first finger 21A. It is assumed that the position is set to a predetermined position (ie, a position above the tip of the first finger 21A).

  The arm mechanism 3 and / or the hand mechanism 2 are controlled such that the tip of the first finger portion 21A moves toward the predetermined target position Tp in a state where the form of the hand mechanism 2 is the above-described search form. When the target 10 is actually present at the above-described assumed position 10 'when being moved, as shown in FIG. 11B, the tip of the third finger portion 21C is an object (the target 10 is placed) The front end portion of the first finger portion 21A comes in contact with the upper surface S1 of the object 10 before contacting the floor surface or the like. Also in FIG. 11B, the white arrow indicates the moving direction of the hand mechanism 2.

If the tip of the first finger 21A contacts the top surface S1 of the object 10 before the tip of the third finger 21C contacts the object, the contact state is the first finger link of the first finger 21A. It is detected by the pressure sensor 70 disposed at 211A. At this time, the detection value of the pressure sensor 70 is acquired by the sensor information acquisition unit 433. The contact position deriving unit 434 derives the contact position between the tip of the first finger 21A and the object 10 based on the detection value of the pressure sensor 70 acquired by the sensor information acquiring unit 433. For example, the contact position deriving unit 434 is acquired by the state amount of each motor of the arm mechanism 3 acquired by the motor state amount acquiring unit 421 of the arm control device 42 and by the motor state amount acquiring unit 432 of the hand control device 43. The contact position between the tip of the first finger 21A and the object 10 is derived based on the state quantities of the respective motors of the hand mechanism 2. Subsequently, the position information correction unit 435 performs position information (position in the vertical direction) of the target 10 acquired by the target information acquisition unit 430 based on the contact position information on the contact position derived by the contact position derivation unit 434. Information) should be corrected. At that time, for example, the shift between the contact position information on the contact position derived by the contact position deriving unit 434 and the position information (position information on the vertical direction) of the object 10 acquired by the object information acquiring unit 430 is If it exceeds the allowable range, it is determined that the correction of the position information (position information in the vertical direction) of the object 10 acquired by the object information acquisition unit 430 is necessary. When it is determined that such correction is necessary, the position information correction unit 435 acquires the target information acquisition unit 430 based on the contact position information on the contact position derived by the contact position derivation unit 434. The position information (vertical position information) of the target 10 is corrected. Thus, when the position information (position information in the vertical direction) of the object 10 is obtained, the position information of the object 10 in the vertical direction can be grasped with high accuracy.

  As a result, when gripping the object 10 by the hand mechanism 2, it becomes possible to grip the object 10 at a desired gripping position in the vertical direction. Therefore, the stability of gripping of the object 10 by the hand mechanism 2 can be improved. In addition, when a plurality of objects of the same shape are arranged at the same height, the position information of one object in the vertical direction can be grasped with high accuracy to grasp the other objects. It becomes possible to use the vertical position information of one object as the vertical position information on the other object.

  On the other hand, with the form of the hand mechanism 2 set as the above-described search form, the arm mechanism 3 and / or the hand mechanism 2 are moved so that the tip of the first finger 21A moves toward the predetermined target position Tp. If the target 10 is not actually present at the above-mentioned assumed position 10 'when the above is controlled, as shown in FIG. 11C, before the tip of the first finger 21A contacts the object, The tip of the three finger portion 21C comes in contact with an object (in the example shown in FIG. 11C, the floor surface fl on which the object 10 is placed). Also in FIG. 11C, the white arrow indicates the moving direction of the hand mechanism 2.

  If the tip of the third finger 21C contacts the floor surface fl before the tip of the first finger 21A contacts an object, the contact state is placed on the first finger link 211 of the third finger 21C. Is detected by the pressure sensor 70. Here, in the search operation control, before the contact between the tip of the first finger 21A and the object is detected by the pressure sensor 70 of the first finger 21A, the pressure sensor of the third finger 21C is detected. When the contact between the tip of the third finger 21C and the floor surface fl is detected by the button 70, the search operation control is canceled at that time. Specifically, when the pressure sensor 70 of the third finger 21C detects the contact between the tip of the third finger 21C and the floor surface fl, the hand control device 43 sends a command to the arm control device 42. Since the command signal is transmitted to stop the operation of the arm mechanism 3, the operation of the arm mechanism 3 for moving the hand mechanism 2 in the direction indicated by the white arrow in FIG. 11C is stopped. According to this, since the search operation control is not continued until the tip of the search finger (the first finger 21A) contacts the floor surface fl, unnecessary increase in tact time can be suppressed. .

  The arm mechanism 3 and / or the hand mechanism 2 are configured such that the tip end portion of the first finger portion 21A moves toward the predetermined target position Tp when the hand mechanism 2 is in the above-described search mode. If the object 10 does not actually exist at the above-mentioned assumed position 10 'when the above is controlled, as shown in FIG. 11D, before the tip of the first finger 21A contacts the object, There is also a possibility that the tip end of the three finger portion 21C comes in contact with the upper surface S1 of the object 10. In that case, when the pressure sensor 70 of the third finger 21C detects the contact between the tip of the third finger 21C and the upper surface S1 of the object 10, the search operation control is stopped. The unnecessary increase in tact time can be suppressed.

  Further, before the pressure sensor 70 of the first finger 21A detects the contact between the tip of the first finger 21A and the object, the pressure sensor 70 of the third finger 21C detects the third finger When the search operation control is stopped by detecting the contact between the tip portion of 21 C and the object, the object information including the position information of the object 10 is the object information acquisition unit 430 of the hand control device 43. Reacquired by. Then, based on the position information of the target 10 included in the target information reacquired by the target information acquisition unit 430, the search operation control is performed again. According to this, it is possible to more accurately grasp the accurate position information of the object 10 in the vertical direction.

  Further, although FIGS. 11A to 11D described above have described search operation control in the case of grasping the position information of the object in the vertical direction as an example, it is also possible to grasp position information of the object in the horizontal direction. Similar search operation control can be applied. In this case, the hand mechanism 2 may be brought close to the object in the horizontal direction with the form of the hand mechanism 2 being a search form. In this case, in the search mode, the position of the tip of the sub search finger in the horizontal direction is a predetermined target position by a distance shorter than the horizontal dimension of the object compared to the position of the search finger. As well as being close, the vertical position of the tip of the sub-searching finger is a position out of the region occupied by the target in the vertical direction, assuming that the target exists at the above-mentioned assumed position. Any form is acceptable. In other words, when grasping the position information of the target portion in the predetermined direction, the hand mechanism 2 is configured such that the position of the tip portion in the sub search finger portion in the predetermined direction is the position of the tip portion in the search finger portion. The position closer to the predetermined target position by a predetermined distance shorter than the dimension of the object in the predetermined direction compared to the position, and the position in the direction orthogonal to the predetermined direction of the fingertip portion in the subsearch finger portion is the object The hand mechanism 2 may be brought close to the object from a predetermined direction in a search mode in which the position is out of the area assumed to exist.

  In the present embodiment, the pressure sensor 70 corresponds to the “contact detection unit” according to the present invention. Further, when an external force (pressure) acts on the tip end portion of the first finger link portion 211, the load applied to the first motor 51 changes. Therefore, an ammeter that detects a change in load applied to the first motor 51 as a change in current value can be used as the "contact detection unit" according to the present invention instead of the pressure sensor 70.

  Further, in the search operation control, the portion of the finger to be brought into contact with the object or an object other than the object (that is, the "predetermined contact region" according to the present invention) may not necessarily be the tip of the finger. For example, as described above, when the first finger portion 21A of the hand mechanism 2 is a search finger portion and the third finger portion 21C is a sub search finger portion, the second finger link portion in the first finger portion 21A The search operation control may be performed so that either one of the second finger link unit 212C in the second finger 212C or the third finger unit 21C contacts an object or an object other than the object. In that case, the position in the predetermined direction of the second finger link portion 212C in the third finger portion 21C is the position in the predetermined direction of the second finger link portion 212A in the first finger portion 21A. On the other hand, it is assumed that the target is present at a position close to the predetermined target position by the predetermined distance described above, and the position of the third finger 21C in the direction orthogonal to the predetermined direction of the second finger link 212C. It may be in the form of being out of position. Furthermore, in the case where a pressure sensor detects contact with an object, each of the second finger link portion 212A and the second finger link portion 212C may be provided with a pressure sensor.

<Flow of search operation control>
Next, the flow of the search operation control described above will be described based on the flowchart shown in FIG. The flow of the search operation control is realized by executing a predetermined control program in the arm control device 42 and the hand control device 43.

  In the flow illustrated in FIG. 13, first, in S101, the target object information acquisition unit 430 acquires target object information on the target object to be gripped this time. Subsequently, in S102, based on the object information acquired in S101, a predetermined target position in the current search operation control is determined.

In S103, the search form of the hand mechanism 2 in the current search operation control is determined based on the object information acquired in S101. Specifically, two fingers of the search finger and the sub search finger are selected from the four fingers 21 of the hand mechanism 2 and the positions of the two fingers in the vertical direction And determine the position in the horizontal direction.

  In S104, the hand mechanism 2 is controlled so that the form of the hand mechanism 2 becomes the search form determined in S103. The processes of S101 to S104 are executed by the hand control unit 431.

  In S105, the arm control unit 420 controls the arm mechanism 3 so that the tip of the search finger of the hand mechanism 2 moves toward the predetermined target position determined in S102. Move it. At this time, the hand control unit 431 maintains the form of the hand mechanism 2 in the search form.

  In S106, it is determined whether or not a touch on the object 10 is detected by the pressure sensor 70 on the search finger. The process of S106 is performed by the sensor information acquisition unit 433. If a negative determination is made in S106, that is, if the search finger is not yet in contact with the object, the process proceeds to S110, where the pressure sensor 70 on the sub search finger detects contact with the object. It is determined whether or not it has been done. If a negative determination is made in S110, neither the search finger portion nor the sub search finger portion is in contact with the object yet, so the processing of S105 is continued.

  On the other hand, if the determination in step S106 is affirmative, it means that the tip of the search finger has come into contact with the object before the tip of the sub search finger comes into contact with the object. Therefore, the process proceeds to S107, and a command signal is transmitted from the hand control device 43 to the arm control device 42, whereby the operation of the arm mechanism 3 is stopped and the movement of the hand mechanism 2 is ended.

  After the process of S107 is performed, the contact position deriving unit 434 derives the contact position when the contact with the object 10 is detected by the pressure sensor 70 of the search finger in S108. Subsequently, in S109, based on the touch position information on the touch position derived by the touch position derivation unit 434 in S108, the position information correction unit 435 determines the position information of the object acquired by the object information acquisition unit 430. Determine if correction is necessary. When it is determined that the correction is necessary, the position information of the object acquired by the object information acquiring unit 430 based on the contact position information on the contact position derived by the contact position deriving unit 434. Is corrected.

  If the determination in S110 is affirmative, the tip of the sub search finger is in contact with the object before the tip of the search finger is in contact with the object. As described above, this means that the actual object does not exist at a place (estimated position) assumed from the position information included in the object information acquired by the object information acquisition unit 430. Therefore, the process proceeds to S111, and a command signal is transmitted from the hand control device 43 to the arm control device 42, whereby the operation of the arm mechanism 3 is stopped and the movement of the hand mechanism 2 is stopped. In that case, the process returns to S101, object information is reacquired, and the search operation control is performed again.

  When the search operation control is performed according to the above-described flow, unnecessary increase in tact time is suppressed when the actual object is not present at the assumed position.

  In the above embodiment, the number of finger portions 21 provided in the hand mechanism 2 is four, but if the hand mechanism 2 has at least two finger portions, a series of the above-described series can be performed. Search operation control can be performed.

DESCRIPTION OF SYMBOLS 1 ... Robot arm, 2 ... Hand mechanism, 20 ... Base part, 21 ... Finger part, 22 ... 1st joint part, 23 ... 2nd joint part, 211 ... First finger link, 212: second finger link, 213: proximal end, 3: arm mechanism, 30a: first joint, 30b: second joint, 30c ... 3rd joint part, 30d ... 4th joint part, 30e ... 5th joint part, 30f ... 6th joint part, 31 ... 1st arm link part, 32 ... third 2 arm link part, 33 ... third arm link part, 34 ... fourth arm link part, 35 ... fifth arm link part, 36 ... connection member, 4 ... pedestal part, 42 ... Arm control device, 420 ... Arm control unit, 421 ... Motor state quantity acquisition unit, 43 ... Hand control device, 430 · · · · · · · Object information acquisition unit, 431 · · · hand control unit, 432 · · · · · · · · motor state quantity acquisition unit, 433 ... sensor information acquisition unit, 51 ... first motor, 52 ... second motor 53: Third motor 70: Pressure sensor

Claims (6)

A hand mechanism having a plurality of fingers and holding the object by the plurality of fingers;
An arm mechanism that changes the position of the hand mechanism;
A contact detection unit provided on at least two predetermined finger portions of the plurality of finger portions of the hand mechanism and detecting that a predetermined contact site on each of the predetermined two finger portions contacts an object When,
When gripping the object by the hand mechanism, the predetermined contact area on the search finger portion which is one finger portion of the predetermined two finger portions and the position where the object is assumed to be present Search operation control for controlling the hand mechanism and / or the arm mechanism so as to move the predetermined contact portion of the search finger toward the predetermined target position from the state where the wheel is separated in the predetermined direction By performing, the contact position when the contact of the predetermined contact site on the search finger with the object is detected by the contact detection unit of the search finger is derived, and in the search operation control The hand mechanism is moved to a predetermined grippable position by controlling the arm mechanism and / or the hand mechanism based on the derived contact position. Thereby gripping the object by the hand mechanism, and a control unit,
In a gripping system comprising
When the search operation control is performed,
The control unit
The position in the predetermined direction of the predetermined contact portion in the subsearch finger portion which is the other finger portion of the predetermined two finger portions is smaller than the predetermined contact portion in the search finger portion. Performing the search operation control in a state in which the hand mechanism is controlled to be close to the predetermined target position by a predetermined distance shorter than the dimension of the object in the predetermined direction;
Before the contact with the object of the predetermined contact site in the search finger is detected by the contact detection unit of the search finger, the object of the predetermined contact site in the sub search finger is detected. When a touch is detected by the touch detection unit of the sub search finger, the search operation control is stopped at that time,
Gripping system. The control unit
The position in the predetermined direction of the predetermined contact portion in the subsearch finger portion which is the other finger portion of the predetermined two finger portions is smaller than the predetermined contact portion in the search finger portion. In addition to the position closer to the predetermined target position by a predetermined distance shorter than the dimension of the target in the predetermined direction, the position of the predetermined position on the sub search finger in the direction orthogonal to the predetermined direction Performing the search operation control in a state where the hand mechanism is controlled such that the position deviates from the area where the object is assumed to exist.
A gripping system according to claim 1. An object of the predetermined contact area on the sub search finger before the contact of the predetermined contact area on the search finger to the target is detected by the contact detection unit of the search finger In the case where the search operation control is canceled by the touch on the sub-search finger being detected by the touch detection unit on the sub-search finger,
The control unit acquires again information on the position where the object is assumed to exist, and performs the search operation control again based on the acquired information.
A gripping system according to claim 1 or 2. A hand mechanism having a plurality of fingers and holding the object by the plurality of fingers;
An arm mechanism that changes the position of the hand mechanism;
A contact detection unit provided on at least two predetermined finger portions of the plurality of finger portions of the hand mechanism and detecting that a predetermined contact site on each of the predetermined two finger portions contacts an object When,
A method of controlling a gripping system comprising:
When gripping the object by the hand mechanism, the predetermined contact area on the search finger portion which is one finger portion of the predetermined two finger portions and the position where the object is assumed to be present Search operation control for controlling the hand mechanism and / or the arm mechanism so as to move the predetermined contact portion of the search finger toward the predetermined target position from the state where the wheel is separated in the predetermined direction By performing, the contact position when the contact of the predetermined contact site on the search finger with the object is detected by the contact detection unit of the search finger is derived, and in the search operation control The hand mechanism is moved to a predetermined grippable position by controlling the arm mechanism and / or the hand mechanism based on the derived contact position. Thereby gripping the object by the hand mechanism, the control method,
The position in the predetermined direction of the predetermined contact portion in the subsearch finger portion which is the other finger portion of the predetermined two finger portions is smaller than the predetermined contact portion in the search finger portion. Executing the search operation control in a state where the hand mechanism is controlled to be close to the predetermined target position by a predetermined distance shorter than the dimension of the object in the predetermined direction;
During execution of the search operation control, before the contact with the search finger unit is detected by the contact detection unit of the search finger unit before the contact with the search finger unit is detected by the sub search finger unit A stop step of stopping the search operation control at that time when the contact to the object of the predetermined contact portion is detected by the contact detection unit of the sub search finger;
Control method of the gripping system, including: In the execution step, the position in the predetermined direction of the predetermined contact portion in the subsearch finger portion which is the other finger portion of the predetermined two finger portions is the predetermined contact portion in the search finger portion And the predetermined direction of the predetermined contact portion of the sub search finger portion in addition to the predetermined position being closer to the predetermined target position by a predetermined distance shorter than the dimension of the object in the predetermined direction. The hand mechanism is controlled such that the position in the orthogonal direction is out of the area where the object is assumed to be present.
The control method of the holding | grip system of Claim 4. An object of the predetermined contact area on the sub search finger before the contact of the predetermined contact area on the search finger to the target is detected by the contact detection unit of the search finger When the search operation control is canceled by the touch detection unit detecting the touch on the sub-search finger, the information on the position where the object is assumed to be present is acquired again. Acquisition step,
A re-execution step of re-executing the search operation control based on the information on the position where the target object is assumed to be acquired again in the re-acquisition step;
The control method of the gripping system according to claim 4 or 5, further comprising

Images