WO2019098027A1

WO2019098027A1 - Gripping system and control method for same

Info

Publication number: WO2019098027A1
Application number: PCT/JP2018/040503
Authority: WO
Inventors: 松尾　芳一; 晋治川畑
Original assignee: Thk株式会社
Priority date: 2017-11-15
Filing date: 2018-10-31
Publication date: 2019-05-23
Also published as: JP7069512B2; JP2019089177A

Abstract

The present invention provides technology that can, in a gripping system comprising a hand mechanism to grip an object with a plurality of fingers, reduce increases in takt time as much as possible by performing a search operation before a gripping operation. When controlling search operation by a prescribed search finger of the plurality of fingers, this gripping system performs search operation control in a state wherein the shapes of the fingers other than the search finger on the hand mechanism are controlled to be a pre-grip shape, which is the same shape as the shape of the fingers other than the search finger when the hand mechanism is moved to a prescribed position in which gripping is possible during gripping operation control. Thus, the time thereafter to transition from search operation control to gripping operation control is shortened, thereby reducing the takt time.

Description

Grip system and control method thereof

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 search operation as described above is performed independently of the gripping operation, the transition from the search operation to the gripping operation takes time, which may increase the tact time. That is, if the search operation is performed by making the form of the hand mechanism completely different from the form suitable for the grasping operation, the form of the hand mechanism is changed from the form for the search operation to the form for the grasping operation after the search operation ends. Need to change to As a result, there is a possibility that the tact time may increase due to the change of the hand mechanism.

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, a tact by performing a search operation before the gripping operation An object of the present invention is to provide a technology capable of suppressing an increase in time as small as possible.

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 a predetermined search finger of the fingers and detecting that a predetermined contact site on the search finger is in contact with an object, and when the object is gripped by the hand mechanism And a control unit configured to control at least one of the hand mechanism and the arm mechanism. Here, the control finger controls 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, thereby the search finger A contact position when the contact of the predetermined contact site with the object at the time of detection by the contact detection unit of the search finger is detected is derived. Next, the control unit controls the arm mechanism and / or the hand mechanism based on the contact position derived to move the hand mechanism to a predetermined grippable position and the hand mechanism performs the movement. It is for holding an object. Further, in the present invention, when moving the predetermined contact portion of the search finger portion toward the predetermined target position of the object, the hand mechanism is moved to the predetermined graspable position. Determine a pre-gripping form which is a form of a finger other than the search finger. Next, the control unit moves the predetermined contact site on the search finger toward the predetermined target position in a state in which the form of the finger other than the search finger is controlled to the pre-grip form. Control the arm mechanism and / or the hand mechanism so that the

According to the present invention, in a gripping system provided with a hand mechanism that grips an object with a plurality of fingers, an increase in tact time by performing a search operation before a gripping operation can be suppressed as small as possible. .

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 1st figure which shows the mode of a hand mechanism when holding operation control is performed. It is a 2nd figure which shows the mode of a hand mechanism when holding operation control is performed. It is a 3rd figure which shows the mode of a hand mechanism when holding operation control is performed. It is a 1st figure which shows the mode of a hand mechanism when search operation control in a present Example is performed. It is a 2nd figure which shows the mode of a hand mechanism when search operation control in a present Example is performed. It is a figure which shows the mode of the hand mechanism at the time of transfering to search operation control from search operation control in a present Example. It is a flowchart which shows the flow of the search operation control which concerns on a present Example. It is a figure showing the state where a plurality of objects were arranged side by side in other examples. It is a 1st figure which shows the operation | movement at the time of changing the attitude | position of a target object by the 1st finger part of a hand mechanism in another Example. It is a 2nd figure which shows the operation | movement at the time of changing the attitude | position of a target object by the 1st finger part of a hand mechanism in another Example. It is a figure which shows the state which held the target object by the 2nd finger part of a hand mechanism, a 3rd finger part, and a 4th finger part in other examples.

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 types of information are acquired based on input by the user, an image captured by a visual sensor, and the like. Further, among the plurality of finger portions of the hand mechanism, at least a predetermined search finger portion is provided with a contact detection portion for detecting that a predetermined contact portion of the search finger portion is in contact with an object.

When gripping an object by the hand mechanism, the control unit first controls the hand mechanism and / or the arm mechanism so as to move the predetermined contact site on the search finger toward the predetermined target position. 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 thus derived, thereby moving the hand mechanism to a predetermined grippable position and causing the hand mechanism to grip the object ( Holding operation control). Here, the predetermined target position is determined based on the position information of the object. 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, when the search operation control is performed, the form of the finger unit other than the search finger unit is suitable for moving the hand mechanism to a predetermined grippable position in the subsequent grip operation control (pre-gripping form) If it is controlled to a form different from the above, it is necessary to change the form of the finger part other than the search finger part to the form before grasping when shifting from the search operation control to the grasping operation control. Therefore, the time taken to shift from the search operation control to the gripping operation control may be long, which may lead to an increase in tact time.

On the other hand, in the gripping system according to the present invention, the search operation control is performed in a state in which the fingers other than the search finger in the hand mechanism are controlled in advance to the form before gripping. When the search operation control is performed by such a method, it is not necessary to change the form of the finger other than the search finger when shifting from the search operation control to the grasping operation control. In that case, the time taken to shift from the search operation control to the gripping operation control can be shortened, and therefore the tact time can be reduced.

<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. It is 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 size, shape, 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 device 42 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.

<Grasping operation control>
Next, an example of gripping operation control performed when gripping the object 10 by the hand mechanism 2 will be described based on FIGS. 11A to 11C. FIG. 11A to FIG. 11C are diagrams showing the state of the hand mechanism 2 when the gripping operation control is executed, in chronological order. The gripping operation control mentioned here is realized by the arm control device 42 controlling the arm mechanism 3 and the hand control device 43 controlling the hand mechanism 2. 11A to 11C show the state of the hand mechanism 2 in the case where the gripping operation control is performed in a state where the search operation control according to the method described later is not performed.

The object 10 shown in FIGS. 11A to 11C is placed alone on the floor surface and has a rectangular parallelepiped shape. Therefore, one side S2 of the object 10 (the side on the left side in FIGS. 11A to 11C) and the other side S3 of the object 10 (the side on the right side in FIGS. 11A to 11C) are exposed. Therefore, the two side surfaces S2 and S3 can be gripped and held by the two finger portions 21. That is, it is possible to directly grasp the object 10 without changing the posture or the position of the object 10. Therefore, in FIGS. 11A to 11C, the second finger portion 21B and the third finger portion 21C in the hand mechanism 2 are set as gripping finger portions, and the two side surfaces S2 and S3 in the object 10 are designated gripping surfaces. The grip operation control is performed by setting to. 11A to 11C, for convenience, only the first finger 21A, the second finger 21B, and the third finger 21C in the hand mechanism 2 are illustrated, and the fourth finger 21D is illustrated. Is omitted.

In the gripping operation control, first, as shown in FIG. 11A, each of the second finger portion 21B and the third finger portion 21C that uses the form of the hand mechanism 2 as the gripping finger portion in the current gripping of the object 10 The distance between the tip end portions (the tip end portion of the first finger link portion 211B of the second finger portion 21B and the tip end portion of the first finger link portion 211C of the third finger portion 21C) is a predetermined gripping surface of the object 10 The hand mechanism 2 is brought close to the object 10 in a state of a gripping approach form in which the predetermined initial spacing df is larger than the spacing dt between two given side faces S2 and S3. The open arrow in FIG. 11A indicates the moving direction of the hand mechanism 2.

Here, when the object 10 is gripped by the second finger portion 21B and the third finger portion 21C of the hand mechanism 2, the above-described gripping approach form is the first finger portion 21A which is a finger portion other than these. And the fourth finger portion 21 D is set so as not to contact the object 10. Such a gripping approach form is determined based on the information on the size and shape of the object 10 acquired by the object information acquisition unit 430. At this time, the predetermined initial interval df described above is determined based on the dimensions of the object 10 acquired by the object information acquisition unit 430.

In the gripping operation control, each motor of the arm mechanism 3 and the hand mechanism 2 are moved to move the hand mechanism 2 to a predetermined graspable position in a state where the form of the hand mechanism 2 is controlled to the above-described gripping approach form. Each motor in each finger 21 is servo-controlled by the arm controller 42 and the hand controller 43, respectively. The predetermined graspable positions in the example shown in FIGS. 11A to 11C are the two side surfaces S2 and S3 of the object 10 between the tip of the second finger 21B and the tip of the third finger 21C. Is the position where it will be located. Then, as shown in FIG. 11B, when the hand mechanism 2 reaches a predetermined grippable position (ie, between the end of the second finger 21B and the end of the third finger 21C) When the two side surfaces S2 and S3 are positioned), the arm mechanism 3 is controlled to stop the movement of the hand mechanism 2. The open arrow in FIG. 11B indicates the moving direction until the hand mechanism 2 reaches a predetermined grippable position.

When the movement of the hand mechanism 2 is stopped by the hand mechanism 2 reaching a predetermined grippable position, as shown in FIG. 11C, the tip of the second finger 21B and the tip of the third finger 21C The second finger portion 21B and the third finger portion 21C are controlled so that the distance between them and the part is smaller than a predetermined initial distance df. In FIG. 11C, the outline arrows indicate the moving directions of the tip of the second finger 21B and the tip of the third finger 21C. As a result, the tip of the second finger 21B is brought into contact with one side S2 of the object 10, and the tip of the third finger 21C is brought into contact with the other side S3 of the object 10, The object 10 is gripped and held by the

finger portions

21B and 21C.

Here, in the hand mechanism 2 according to the present embodiment, the finger portions functioning as gripping finger portions are not limited to the second finger portion 21B and the third finger portion 21C as shown in FIG. 11A to FIG. The finger 21 can function as a gripping finger. In addition, three fingers of the four fingers 21 of the hand mechanism 2 may be used as gripping fingers, or all four fingers may be used as gripping fingers.

By the way, the position information of the target 10 acquired by the target information acquisition unit 430 may include an 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. In such a case, when the above-described gripping operation control is performed based on the position information of the object 10 acquired by the object information acquiring unit 430, it becomes difficult to stably hold the object 10. There is a possibility. Therefore, in order to stably hold the object by the hand mechanism 2 of the robot arm 1, it is desirable to perform holding operation control after grasping the position information of the object with high accuracy.

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

<Search operation control>
Hereinafter, search operation control according to the present embodiment will be described. 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.

In the search operation control in the present embodiment, a predetermined finger (corresponding to the “search finger” according to the present invention) of the four fingers 21 of the hand mechanism 2 is brought into contact with the object. The contact position between the predetermined finger and the object 10 is derived. Then, based on the derived contact position, it is determined whether the correction of the position information of the object acquired by the object information acquisition unit 430 is necessary, and it is determined that the correction is necessary. The position information of the object acquired by the object information acquisition unit 430 is corrected. As a result, the position information of the object 10 is grasped with high accuracy.

Here, in the above-described search operation control, when the form of the hand mechanism 2 is controlled to a form completely different from the above-described form for gripping approach, the time taken to shift from the subsequent search operation control to the gripping action control becomes long. there is a possibility. For example, the forms of the second finger portion 21B and the third finger portion 21C that function as gripping finger portions when gripping the object 10 as illustrated in FIGS. 11A to 11C are illustrated in FIGS. 11A to 11B. When the search operation control is performed in a state controlled to a form different from the form of the second finger unit 21B and the third finger unit 21C in the grasping approach form, when shifting from the search operation control to the grasping operation control, Since it is necessary to change the form of the second finger portion 21B and the third finger portion 21C, the time taken to shift from the search operation control to the gripping operation control may be long, which may lead to an increase in tact time.

Therefore, in the search operation control of the present embodiment, the form of the finger parts other than the search finger part is the same as the form of those finger parts in the approach form for gripping (corresponding to the "pre-gripping form" according to the present invention). The search operation control is performed while being controlled to the form. Hereinafter, search operation control in the present embodiment will be described based on FIGS. 12A to 12C. 12A to 12C are diagrams showing the state of the hand mechanism 2 when the search operation control according to the present embodiment is executed, in chronological order. 12A to 12C show the case where the search operation control is performed as a preparation step when holding the object 10 as shown in FIGS. 11A to 11C described above by the hand mechanism 2. It shows the situation. 12A to 12C show the operation of the hand mechanism 2 in the case where it is intended to grasp positional information in the vertical direction (vertical direction in FIGS. 12A to 12C) of the object 10.

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. 12A) with the form of the hand mechanism 2 in the search approach form as shown in FIG. 12A. Thus, the hand mechanism 2 is brought close to the area where the object 10 is present. At that time, a motor provided at each joint 30a, 30b, 30c, 30d, 30e, 30f of the arm mechanism 3 so that a predetermined part of the search finger moves toward the predetermined target position Tp, and The first motor 51, the second motor 52, and the third motor 53 for driving the joints of the fingers 21 of the hand mechanism 2 respectively are servo-controlled by the arm controller 42 and the hand controller 43. Be done.

Here, in the “approach form for search” in this embodiment, the form of the second finger unit 21B and the third finger unit 21C, which function as grasping finger units when performing grasping operation control, is the form before grasping in the grasping approach form (In other words, as shown in FIGS. 11A and 11B, the distance between the tips of the two

finger portions

21B and 21C is a predetermined initial distance df) and other than the

finger portions

21B and 21C. The hand of a predetermined search finger part (the first finger part 21A in the example shown in FIG. 12A to FIG. 12C) among the finger parts is a form in which only the search finger part is in contact with the object 10 It is a form of mechanism 2. Further, the “predetermined target position Tp” referred to here is a position corresponding to the position information of the object 10 included in the object information acquired by the object information acquisition unit 430 (hereinafter referred to as “estimated position 10 ′” When it is assumed that the object 10 is present, the position is the inside of the object 10. The predetermined target position Tp is determined based on the position information of the target 10 included in the target information acquired by the target information acquisition unit 430.

As the form of the hand mechanism 2 is shown to FIG. 12A, the form of the 2nd finger part 21B and the 3rd finger part 21C is a pre-gripping form in the approach form for holding (namely, distance of the tip part of

finger parts

21B and 21C) Is the form in which the predetermined initial spacing df is larger than the predetermined spacing dt between the predetermined gripping surfaces S2 and S3 on the target 10, and only the first finger portion 21A contacts the target 10 With the arm mechanism 3 and / or the hand mechanism 2 controlled so that the tip of the first finger 21A moves toward the predetermined target position Tp determined as described above, As shown in 12B, the tip of the first finger 21A contacts the top surface S1 of the object 10. Also in FIG. 12B, the white arrow indicates the moving direction of the hand mechanism 2. Further, in FIG. 12B, the contact position between the top surface S1 of the object 10 and the tip end portion of the first finger portion 21A is surrounded by an alternate long and short dash line. As described above, when the tip of the first finger 21A contacts the top surface S1 of the object 10, the pressure contact is provided on the tip (first finger link 211A) of the first finger 21A. It is detected by the sensor 70. At this time, the detection value of the pressure sensor 70 is acquired by the sensor information acquisition unit 433. When contact between the first finger 21A and the object 10 is detected by the pressure sensor 70 of the first finger 21A, the contact position deriving unit 434 derives the contact position. Here, 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 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 amount of state of each motor of the hand mechanism 2 as described above. Then, based on the touch position information on the touch position derived by the touch position deriving unit 434, the position information correction unit 435 determines the position information (vertical position information of the object 10 acquired by the object information acquisition unit 430). Determine if correction is required. 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. When the position information (position information in the vertical direction) of the object 10 is thus obtained, the position information of the object 10 can be grasped with high accuracy.

When the position information in the vertical direction of the object 10 is grasped with high accuracy by executing such search operation control, the position in the vertical direction of the gripping finger portion in the above-described gripping operation control is set to a predetermined graspable position. Control with high accuracy. As a result, the stability of gripping of the object 10 by the hand mechanism 2 can be improved. In addition, when the same object 10 is arranged in multiple numbers at the same height, the position information of one object 10 in the vertical direction can be grasped with high accuracy, so that the other objects 10 can be gripped. The hand mechanism 2 can be controlled using vertical position information of the one object 10 as vertical position information on the other object 10.

Further, in the present embodiment, the forms of the second finger unit 21B and the third finger unit 21C that function as gripping finger units at the time of execution of gripping operation control are the forms of those

finger units

21B and 21C in the gripping approach configuration ( Since the search operation control is executed in the same form as the pre-gripping mode, the search operation control can be shifted to the gripping operation control without changing the form of the

finger portions

21B and 21C. it can. For example, as shown in FIG. 12B described above, after the tip of the first finger 21A as a search finger comes in contact with the object 10, as shown in FIG. 13, the tip of the first finger 21A The arm mechanism 3 is moved such that the hand mechanism 2 approaches a predetermined graspable position as shown by the white arrow Ar1 in FIG. 13 while being separated from the object 10 as shown by the white arrow Ar2 in FIG. The motors and the motors in the fingers 21 of the hand mechanism 2 may be servo-controlled by the arm control device 42 and the hand control device 43, respectively. Thus, when transitioning from search operation control to gripping operation control, it is possible to suppress an increase in tact time caused by changing the form of the hand mechanism 2 from the search approach form to the gripping approach form. it can.

<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. 14, 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, based on the object information acquired in S101, the search approach form of the hand mechanism 2 in the current search operation control is determined. In detail, based on the information regarding the dimension and shape of the target object 10 contained in the target object information acquired by S101, first, the approach form for holding | grip in holding | grip operation control is determined. Subsequently, the search finger portion is selected from the four finger portions 21 of the hand mechanism 2. Furthermore, with the form of the selected search finger part (the finger part other than the search finger part is controlled to the form of the finger parts in the grip approach form (pre-gripping form), only the search finger part is controlled) Determine the form of contact with the object 10).

In S104, the hand mechanism 2 is controlled so that the form of the hand mechanism 2 becomes the search approach form determined in S103. The processes of S101 to S104 are executed by the hand control device 43.

In S105, the arm control device 42 controls the arm mechanism 3 so that the tip of the search finger portion of the hand mechanism 2 moves toward the predetermined target position determined in S102. Move it. At this time, the hand control device 43 maintains the form of the hand mechanism 2 in the search approach 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 returns to S105. On the other hand, if a positive determination is made in S106, the tip of the search finger has come into contact with the object, so the process proceeds to S107.

In S107, the 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.

In S108, 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. 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.

When the search operation control is performed according to the above-described flow, after the end of the search operation control, the gripping operation control can be promptly started without changing the form of the finger other than the search finger in the hand mechanism 2 Can. Therefore, the time taken to shift from the search operation control to the gripping operation control is shortened. As a result, the increase in tact time due to the execution of the search operation control before the execution of the gripping operation control can be reduced as much as possible.

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 unit 21A of the hand mechanism 2 is used as a search finger unit, search operation control is performed so that the second finger link unit 212A in the first finger unit 21A contacts an object. You may go. In such a case, the relative position and posture of the first finger 21A in the search approach form may be controlled to a relative position and posture in which only the second finger link 212A in the first finger 21A contacts the object 10. Good. Furthermore, in the case where a pressure sensor detects contact with an object, the pressure sensor may be provided on the second finger link 212A of the first finger 21A.

Other Embodiments
In the above-described embodiment, although the case where the object 10 can be directly gripped is taken as an example, the case where it is impossible to directly grip the object 10 is also conceivable. Here, when the object 10 is gripped by the hand mechanism 2, at least two surfaces out of the six surfaces of the object 10 are set as predetermined gripping surfaces, and each of the predetermined gripping surfaces of the hand mechanism 2 is used. It is necessary to bring one of the fingers 21 into contact and hold the object 10 by the fingers 21. However, as shown in FIG. 15, in the state where the plurality of objects 10 (10 ') to be gripped by the hand mechanism 2 are sequentially arranged in contact with each other, predetermined gripping of the object 10 is performed. The face may be placed in contact with the adjacent object 10 '. For example, in the example shown in FIG. 15, one gripping surface S6 of the two predetermined gripping surfaces S5 and S6 of the object 10 is in contact with the adjacent object 10 '. In such a case, the gripping surface S6 of the object 10 is not exposed. Therefore, the finger portion 21 of the hand mechanism 2 can not be brought into contact with the gripping surface S6 of the object 10 while the object 10 is in the state shown in FIG. Can not do it.

Therefore, in the gripping operation control in the case where the object 10 in the situation as shown in FIG. 15 is gripped by the hand mechanism 2, first, as the state changing finger portion among the four finger portions 21 in the hand mechanism 2. By changing the posture of the object 10 with one functioning finger portion, the gripping surface S6 of the object 10 is exposed, and then it functions as a gripping finger portion among the four finger portions 21 in the hand mechanism 2 The object 10 is gripped by bringing the plurality of finger portions to be brought into contact with the gripping surfaces S5 and S6 of the object 10.

Hereinafter, an execution procedure of the gripping operation control when gripping the object 10 in the situation shown in FIG. 15 by the hand mechanism 2 will be described based on FIG. 16A to FIG. 16C. In the following description, it is assumed that the finger portion functioning as the state changing finger portion is the first finger portion 21A, and the finger portions functioning as the gripping finger portions are the second to

fourth finger portions

21B, 21C, and 21C. Do. 16A and 16B are diagrams showing an operation when the posture of the object 10 is changed by the first finger 21A of the hand mechanism 2. FIG. 16C is a diagram showing a state in which the object 10 is gripped by the second finger portion 21B, the third finger portion 21C, and the fourth finger portion 21D of the hand mechanism 2.

In the example shown in FIG. 15, although one gripping surface S6 of the object 10 is in contact with the adjacent object 10 ', the upper surface S4 of the object 10 is exposed, so It is possible to bring the finger 21 into contact with the top surface S4 of the object 10. Therefore, in the gripping operation control in the present embodiment, first, as shown in FIG. 16A, the tip end portion of the first finger portion 21A functioning as the state changing finger portion is brought into contact with the upper surface S4 of the object. In the step of bringing the first finger 21A into contact with the upper surface S4 of the object 10, the

fingers

21B, 21C, 21D of the

other fingers

21B, 21C, 21D in the hand mechanism 2 are the object 10 Form that does not come in contact with each other, and that the positions of the

finger portions

21B, 21C, and 21D face the corresponding predetermined gripping surfaces when the object 10 is in a predetermined graspable state described later It corresponds to the "pre-gripping form" according to the present invention.

When the tip of the first finger 21A functioning as a state changing finger contacts the upper surface S4 of the object 10, as shown in FIG. 16B, the first finger link 211A is moved by the first finger 21A. While being in contact with the upper surface S4 of the object 10, the object 10 can be tilted to the front. That is, the object 10 can be tilted in the direction in which the gripping surface S6 of the object 10 is separated from the adjacent object 10 '. Thus, the distance between the object 10 and the adjacent object 10 'can be increased by changing the posture of the object 10 by the first finger 21A functioning as the state changing finger. . Thereby, grasping side S6 in subject 10 can be exposed. As a result, it becomes possible to contact fingers other than the first finger 21A in the hand mechanism 2 not only on the other gripping surface S5 of the object 10 but also on one gripping surface S6. In the following, the state of the object 10 in which the finger portion 21 of the hand mechanism 2 can be brought into contact with both of the predetermined gripping surfaces S5 and S6 of the object 10 in this manner is referred to as “predetermined state”. It is referred to as "graspable state".

When one gripping surface S6 of the object 10 is exposed by the object 10 being in the predetermined graspable state described above, as shown in FIG. 16C, the first finger of the second finger portion 21B is held on the gripping surface S6. By bringing the first finger link portion 211D of the link portion 211B and the fourth finger portion 21D into contact with each other and bringing the first finger link portion 211C of the third finger portion 21C into contact with the other gripping surface S5 of the object 10 The object 10 is gripped. In addition, it is not necessary to make two finger parts contact the one holding surface S6 in the target object 10 necessarily. That is, while bringing one finger portion into contact with one gripping surface S6 of the object 10 and bringing two finger portions into contact with the other gripping surface S5 of the object 10, the object 10 is You may hold it. Moreover, while making one finger part contact one grip surface S6 in the target object 10, the other grip surface S5 in the target object 10 also makes the target object 10 contact with one finger part. You may hold it. That is, in a hand mechanism having three fingers, one finger is made to function as a state changing finger, and the remaining two fingers are made to function as gripping fingers to make the object You may hold it.

As described above, in the case where the gripping operation control accompanied by the posture change of the object 10 is performed, in the search operation control performed as a preparatory step of the gripping operation control, the form of the hand mechanism 2 is The form is the same as the form of the state changing finger when the tip of the finger functioning as the state changing finger is brought into contact with the object 10 in gripping operation control, and the finger other than the search finger The search operation control may be performed in a state in which the form of the unit is controlled to be the same as the form before gripping the finger unit that functions as the gripping finger unit in the gripping operation control. In short, in a state where the form of the hand mechanism 2 is controlled to the form shown in FIG. 16A, the search operation is performed so that only the first finger 21A functioning as the state change finger in gripping control is in contact with the object 10 Control should be performed. Then, when shifting from the search operation control to the gripping operation control, the search finger of the hand mechanism 2 is kept in contact with the upper surface S4 of the object 10, so that the search finger is immediately moved. It can function as a state change finger. When the search operation control is performed by such a method, it is not necessary to change the form of the hand mechanism 2 when shifting from the search operation control to the grasping operation control, and therefore the tact time can be reduced.

In the above embodiment, although the number of finger portions 21 provided in the hand mechanism 2 is four, if the hand mechanism 2 has at least three finger portions, the search operation as described above is performed. The transition from control to gripping 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

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 a predetermined search finger among the plurality of fingers of the hand mechanism and detecting that a predetermined contact site on the search finger is in contact with an object;
A control unit configured to control the hand mechanism and / or the arm mechanism when gripping the object by the hand mechanism;
Equipped with
The control unit controls 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, whereby the predetermined in the search finger The contact position when the contact of the contact site to the object is detected by the contact detection unit of the search finger is derived, and the arm mechanism and / or the hand are based on the derived contact position. By controlling the mechanism, the hand mechanism is moved to a predetermined graspable position, and the object is gripped by the hand mechanism.
In the gripping system
When moving the predetermined contact site on the search finger toward the predetermined target position on the object,
The control unit
Determining a pre-gripping form that is a form of a finger other than the search finger suitable to move the hand mechanism to the predetermined grippable position;
The arm mechanism is configured to move the predetermined contact area of the search finger toward the predetermined target position while controlling the shape of the finger other than the search finger to the pre-grip mode. And / or a gripping system that controls the hand mechanism.
The hand mechanism comprises three or more fingers,
When the control unit causes the hand mechanism to grip the object, at least one finger of the three or more fingers is brought into contact with the object, and the posture of the object is obtained. And / or function as a state changing finger for changing the position, and at least two fingers of the fingers other than the state changing finger are changed in posture and / or position by the state changing finger Function as a gripping finger for gripping the target in the
When moving the predetermined contact site on the search finger toward the predetermined target position,
The control unit is configured to control one finger unit of the finger units functioning as the state changing finger unit in a state in which the form of the finger unit functioning as the gripping finger unit is controlled to the pre-gripping mode. Function as a finger,
A gripping system according to claim 1.
The hand mechanism comprises three or more fingers,
When the control unit causes the hand mechanism to hold the object, the control unit is configured to have two finger units that function as gripping finger units among the three or more finger units. Moving the hand mechanism to the predetermined grippable position in a state in which the distance between the tip end portions of the object is controlled to be a predetermined initial distance larger than the distance between two side surfaces which are predetermined holding surfaces of the object; In a state in which the hand mechanism has reached the predetermined graspable position, the distance between the tips of the two finger portions functioning as the grasping finger portion is made smaller than the predetermined initial distance. Holding the object with fingers and holding the object,
When moving the predetermined contact site on the search finger toward the predetermined target position,
The control unit
A mode in which the distance between the tips of the two finger portions functioning as the gripping finger portions when gripping the object by the hand mechanism is the predetermined initial distance is determined as the pre-gripping mode, and the hand The gripping when the object is gripped by the hand mechanism in a state in which the form of the two finger portions functioning as the gripping finger portion when gripping the object by the mechanism is controlled to the form before the gripping A finger part other than the finger part functioning as a finger part is made to function as the search finger part
A gripping system according to claim 1.
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 a predetermined search finger among the plurality of fingers of the hand mechanism and detecting that a predetermined contact site on the search finger is in contact with an object;
A method of controlling a gripping system comprising:
By 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, the predetermined contact portion of the search finger is moved. Deriving a contact position when contact with an object is detected by the contact detection unit of the search finger, and controlling the arm mechanism and / or the hand mechanism based on the derived contact position. In the control method of moving the hand mechanism to a predetermined grippable position to cause the hand mechanism to grip the object,
When moving the predetermined contact site on the search finger toward the predetermined target position,
Determining a pre-gripping form in the form of a finger other than the search finger suitable for moving the hand mechanism to the predetermined graspable position;
In a state in which the form of the finger other than the search finger is controlled to the pre-grip form, the predetermined contact portion of the search finger is moved toward the predetermined target position of the object. And a control step of controlling the arm mechanism and / or the hand mechanism.
Control method of gripping system.
At least one finger of the three or more fingers is brought into contact with the object when the object is gripped by the gripping system in which the hand mechanism includes three or more fingers. The finger functions as a state changing finger that changes the posture and / or position of the object above, and at least two fingers of the fingers other than the state changing finger are the state changing finger. A control method of a gripping system, which functions as a gripping finger that grips the object in a state in which the posture and / or the position is changed by
In the determining step, the pre-gripping form of the finger unit functioning as the gripping finger unit when gripping the object by the hand mechanism is determined.
In the control step, the hand mechanism is controlled in a state in which the form of the finger portion functioning as the gripping finger portion when gripping the object by the hand mechanism is controlled to the pre-gripping form determined in the determination step. Causing one finger unit of the finger units functioning as the state change finger unit when holding the object by the function as the search finger unit
The control method of the holding | grip system of Claim 4.
When the hand mechanism grips the object by a gripping system having three or more fingers, the form of two fingers functioning as gripping fingers among the three or more fingers is used. The hand mechanism is controlled in such a manner that the distance between the tips of the two finger portions is a predetermined initial distance greater than the distance between two side surfaces which is a predetermined gripping surface of the object; When the hand mechanism is moved to the graspable position and the hand mechanism reaches the predetermined graspable position, the distance between the tips of the two finger portions functioning as the grasping finger portion is smaller than the predetermined initial distance A control method of a gripping system in which the object is held and gripped by the two fingers by
In the determination step, a mode in which a distance between tip portions of two finger portions functioning as the gripping finger portion when gripping the object by the hand mechanism is the predetermined initial distance Decided on
In the control step, in a state in which the form of the two finger portions functioning as the gripping finger portion when gripping the object by the hand mechanism is controlled to the pre-gripping form determined in the determination step, A finger portion other than the two finger portions functioning as the gripping finger portion when gripping the object by the hand mechanism is caused to function as the search finger portion.
The control method of the holding | grip system of Claim 4.