WO2018212189A1 - Gripping system - Google Patents

Abstract

A gripping system, wherein a control device servo-controls the location of a prescribed contact site of a prescribed finger part of a hand mechanism according to a prescribed servo-control structure in a manner such that the prescribed contact site moves toward a target location of a target object determined on the basis of target object location information. In addition, before the prescribed contact site reaches the target location, the control device invalidates a location servo-loop that includes a feedback system pertaining at least to the location of the prescribed servo-control structure, when a contact detection unit detects contact with the target object at the prescribed contact site. As a result, it is possible to favorably ascertain the location of a target object.

Description

Gripping system

The present invention relates to a gripping system including a hand mechanism for gripping an object with a plurality of fingers.

Conventionally, a hand mechanism that is attached to a robot arm or the like and grips an object with a plurality of fingers has been developed. For example, Patent Document 1 discloses a robot apparatus including a hand mechanism having a plurality of finger parts (multi-finger hand part) and a robot arm having the hand mechanism attached to the tip. In the robot apparatus described in Patent Document 1, a force sensor is provided at each finger portion of the hand mechanism. And the contact position of this finger part and a target object is detected by this force sensor. In addition, this robot apparatus 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 with the visual sensor. Further, the position information of the object acquired from the image data is corrected based on the information on the contact position detected by the force sensor.

Japanese Patent No. 5505138

When the object is gripped by the hand mechanism as described above, the position of the object is made higher by bringing the finger part of the hand mechanism into contact with the object and deriving the contact position. It is possible to grasp with accuracy. As described above, grasping the position of the object with high accuracy is very preferable for improving the stability of gripping the object by the hand mechanism.

However, when the finger part of the hand mechanism is brought into contact with the object in order to grasp the position of the object, if the speed of the finger part when contacting the object is high, the object or the finger part There is a risk of damage to itself. On the other hand, if the moving speed of the hand mechanism when the finger is brought into contact with the object is reduced in order to suppress damage to the object or the finger itself, the tact time becomes longer.

The present invention has been made in view of the above problems, and provides a technique capable of more appropriately grasping the position of an object in order to grasp the object by a hand mechanism. With the goal.

A gripping system according to the present invention includes an arm mechanism, a hand mechanism that is attached to the arm mechanism and grips an object with a plurality of fingers, an acquisition unit that acquires position information of the object, and the object In the gripping system, comprising: a control device that controls the position of the hand mechanism by controlling the arm mechanism and the hand mechanism according to a predetermined servo control structure for controlling the position of the hand mechanism. Are provided corresponding to at least a predetermined finger portion of the plurality of finger portions and a driving portion that drives the joint portion in the plurality of finger portions, and a predetermined contact portion on the tip side from the joint portion. A contact detection unit that detects contact with the object, and the control device determines based on the position information of the object acquired by the acquisition unit. The position of the predetermined contact portion is servo-controlled according to the predetermined servo control structure so that the predetermined contact portion of the predetermined finger portion of the hand mechanism moves toward a target position of the object to be moved. If the contact of the predetermined contact portion to the object is detected by the contact detection unit before the predetermined contact portion reaches the target position, a feedback system related to at least the position in the predetermined servo control structure Disable the position servo loop containing.

According to the present invention, since the object is gripped by the hand mechanism, the position of the object can be grasped more suitably.

It is a figure which shows schematic structure of the robot arm which concerns on an Example. It is a perspective view of the hand mechanism which concerns on an Example. It is a top view of the hand mechanism which concerns on an Example. It is a side view of the finger | toe part of the hand mechanism which concerns on an Example. It is the figure which looked at the front-end | tip part side of the finger | toe part of the hand mechanism which concerns on an Example from the direction of the arrow A of FIG. It is a figure which shows the internal structure of the connection part vicinity of the finger part in a base part, and the internal structure of the base end part in a finger part, and a 2nd joint part of the hand mechanism which concerns on an Example. It is a figure which shows the internal structure of the 1st joint part in a finger part, and the 2nd finger link part of the hand mechanism which concerns on an Example. It is a figure which shows the movable range of the 2nd joint part in the finger | toe 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 | toe part of the hand mechanism which concerns on an Example. It is a figure which shows arrangement | positioning of the pressure sensor in the 1st link part of the finger | toe part of the hand mechanism which concerns on an Example. It is a block diagram which shows each function part contained in the arm control apparatus and hand control apparatus which concern on an Example. It is a conceptual diagram of the servo control structure for servo-controlling the position of an arm mechanism and a hand mechanism. It is the 1st figure which showed the mode of the hand mechanism when the search operation control which concerns on an Example was performed along the time series. It is the 2nd figure which showed the mode of the hand mechanism when search operation control concerning an example was performed along a time series. It is the 3rd figure which showed the mode of the hand mechanism when the search operation control which concerns on an Example was performed along the time series. It is the 1st figure which showed the mode of the hand mechanism when positioning operation control concerning an example was performed along a time series. It is the 2nd figure which showed the mode of the hand mechanism when positioning operation control concerning an example was performed along a time series. It is the 3rd figure which showed the mode of the hand mechanism when the positioning operation control which concerns on an Example was performed along the time series. It is the 4th figure which showed the mode of the hand mechanism when positioning operation control concerning an example was performed along a time series. It is the 5th figure which showed the mode of the hand mechanism when positioning operation control concerning an example was performed along a time series. It is a figure for demonstrating the 1st other example of the position correction of the hand mechanism in the positioning operation control which concerns on an Example. It is a figure for demonstrating the 2nd other example of the position correction of the hand mechanism in the positioning operation control which concerns on an Example. It is the figure which showed the positional relationship of the horizontal direction of each finger part for a grip of a hand mechanism when a gripping operation control which concerns on an Example was performed, and a target object along a time series. It is a flowchart which shows the flow of the search operation control which concerns on an Example. It is a part of flowchart which shows the flow of positioning operation control and gripping operation control which concern on an Example. It is another one part of the flowchart which shows the flow of positioning operation control and gripping operation control which concern on an Example. It is another one part of the flowchart which shows the flow of positioning operation control and gripping operation control which concern on an Example.

In the gripping system according to the present invention, the position information of the object gripped by the hand mechanism is acquired by the acquisition unit. Here, the acquisition unit acquires position information of the target object based on an input by a user, an image captured by a visual sensor, or the like. Each finger part in the hand mechanism is provided with a drive part for driving the joint part in each finger part. Furthermore, the contact detection part is provided corresponding to at least the predetermined | prescribed finger part among the several finger parts in a hand mechanism. A contact detection part detects that the predetermined contact site | part of the front-end | tip part side contacted the target object from the joint part of the finger | toe part.

In the gripping system, the control device controls the arm mechanism and the hand mechanism according to a predetermined servo control structure, so that the position of the hand mechanism relative to the object, that is, the position of the predetermined contact portion on the predetermined finger portion is servo-controlled. Is done. Servo control related to the position of the predetermined contact portion is executed by the control device, thereby positioning the predetermined contact portion with respect to the object, for example, positioning for gripping the object or positioning for other purposes. Can be realized. The predetermined servo control structure is not limited to a specific structure as long as the position of the hand mechanism can be servo-controlled. For example, the predetermined servo control structure may be a structure including a position servo loop including a position feedback system, a speed servo loop including a speed feedback system, and a current servo loop including a current feedback system. A system may be included. In addition, the target position of the object is determined based on the position information of the object acquired by the acquisition unit.

In the gripping system according to the present invention, when the predetermined contact portion of the predetermined finger portion is moved toward the target position according to the predetermined servo control structure, the predetermined finger portion is reached before the target position is reached. When the contact detection unit detects contact of the predetermined contact portion with the object, the control device invalidates at least the position servo loop in the predetermined servo control structure. When the position servo loop is invalidated in this manner, the driving force for positioning the predetermined contact portion is not applied to the joint portion from the drive portion, so that the predetermined contact portion on the predetermined finger portion is not applied. When an external force is applied, the joint portion of the predetermined finger portion bends within a movable range allowed by the mechanical structure. Therefore, when the position servo loop is invalidated when a predetermined contact portion of the predetermined finger contacts the target object before reaching the target position, the joint portion is bent. According to this, it is possible to reduce the collision force acting on the predetermined finger part and the target object due to the contact between the predetermined finger part and the damage of the finger part of the hand mechanism as much as possible. By suppressing the position of the target object, it is possible to realize a suitable position.

More preferably, the control device is a position of the predetermined contact portion when contact of the predetermined contact portion with the object at the predetermined finger portion is detected by the contact detection unit. The contact position may be derived, and the position information of the object acquired by the acquisition unit may be corrected based on the contact position information regarding the contact position. Here, until the contact detection unit detects contact of the predetermined finger portion with the predetermined contact portion, the predetermined contact portion is contacted according to a predetermined servo control structure. The position of the part is in a servo controlled state. Therefore, the reaction force generated by the contact with the object can be detected by the contact detection unit. As a result, it is possible to detect contact of the predetermined finger with the object. Therefore, in the present invention, the control device derives the contact position of the predetermined contact portion when the contact of the predetermined contact portion on the predetermined finger portion to the object is detected by the contact detection unit, and the contact Based on the contact position information regarding the position, the position information of the object acquired by the acquisition unit is corrected. The fact that the predetermined contact portion has come into contact with the object before reaching the target position means that the actual position of the object and the position of the object acquired by the acquisition unit are shifted. Therefore, by grasping the position information of the object based on the contact position of the predetermined contact part derived as described above, the object can be gripped more suitably by the hand mechanism.

Thus, according to the gripping system according to the present invention, it is possible to reduce the collision force generated when the tip of the predetermined finger is brought into contact with the object. Therefore, the object or the finger itself is damaged due to the contact without reducing the moving speed of the hand mechanism when the predetermined contact portion of the predetermined finger is brought into contact with the object. Can be suppressed. Therefore, it is possible to grasp the position of the target object with higher accuracy while suppressing the tact time from becoming longer. Further, by correcting the position information of the object based on the contact position described above, the position of the object can be grasped with higher accuracy, and thus the hand mechanism can grasp the object more stably. can do.

<Example>
Specific embodiments of the present invention will be described below with reference to 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 those 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 diagram illustrating 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 portion 4. A hand mechanism 2 is attached to one end of the arm mechanism 3. The other end of the arm mechanism 3 is attached to the pedestal portion 4. The hand mechanism 2 includes a base portion 20 connected to the arm mechanism 3 and four finger portions 21 provided on the base portion 20. The detailed configuration of the hand mechanism 2 will be described later.

<Arm mechanism>
The arm mechanism 3 includes a first arm link portion 31, a second arm link portion 32, a third arm link portion 33, a fourth arm link portion 34, a fifth arm link portion 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 around the axis of the first arm link portion 31 with respect to 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 at the second joint portion 30b. The first arm link part 31 and the second arm link part 32 are connected so that their central axes intersect perpendicularly. A motor for rotating the first arm link part 31 around the axis of the second arm link part 32 around the other end side with respect to the second arm link part 32 is provided in the second joint part 30b. (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 30c. The third joint part 30 c is provided with a motor (not shown) for rotating the second arm link part 32 relative to the third arm link part 33.

Similarly, the other end side of the third arm link portion 33 is connected to one end side of the fourth arm link portion 34 at the fourth joint portion 30d. Further, the other end side of the fourth arm link portion 34 is connected to the fifth arm link portion 35 by a fifth joint portion 30e. The fourth joint portion 30d is provided with a motor (not shown) for rotating the third arm link portion 33 relative to the fourth arm link portion 34. Further, the fifth joint portion 30e is provided with a motor (not shown) for rotating the fourth arm link portion 34 relative to the fifth arm link portion 35. Further, the fifth arm link portion 35 is connected to a connection member 36 disposed vertically from the pedestal portion 4 by a sixth joint portion 30f. The fifth arm link portion 35 and the connection member 36 are connected so that their central axes are coaxial. The sixth joint portion 30f is provided with a motor (not shown) for rotating the fifth arm link portion 35 around the axes of the fifth arm link portion 35 and the connection member 36. With the arm mechanism 3 having 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 with reference to FIGS. FIG. 2 is a perspective view of the hand mechanism 2. FIG. 3 is a top view of the hand mechanism 2. In FIG. 3, the arrows indicate the rotation movable ranges of the finger portions 21. As shown in FIGS. 2 and 3, in the hand mechanism 2, the four fingers 21 on the base 20 are centered on the axis in the longitudinal direction of the hand mechanism 2 (direction perpendicular to the paper surface in FIG. 3). On the circumference, they are arranged at equiangular intervals (ie, 90 deg intervals). The four finger portions 21 all have the same structure and the same length. However, the operation of each finger 21 is controlled independently.

4 to 10 are diagrams for explaining the configuration of the finger portion 21 of the hand mechanism 2 and its driving mechanism. FIG. 4 is a side view of the finger part 21. In FIG. 4, the base portion 20 is shown in a transparent state, and a part of the internal structure of the finger portion 21 located inside the base portion 20 is also shown. FIG. 5 is a view of the distal end side of the finger portion 21 as viewed from the direction of arrow A in FIG. 4 and 5, a part of a second finger link part 212 of the finger part 21 to be described later is shown in a transparent state, and the internal structure of the second finger link part 212 is also shown. Yes.

2 and 4, each finger portion 21 has a first finger link portion 211, a second finger link portion 212, and a base end portion 213. The base end portion 213 of the finger portion 21 is connected to the base portion 20. Here, the base end portion 213 is connected to the base portion 20 so as to be rotatable about the longitudinal axis of the finger portion 21 (direction perpendicular to the paper surface in FIG. 3) with respect to the base portion 20, as indicated by an arrow in FIG. Yes. In the finger part 21, one end of the second finger link part 212 is connected to the base end part 213. A second joint portion 23 is formed at a connection portion between the second finger link portion 212 and the base end portion 213.

Here, the drive mechanism of the base end portion 213 and the drive mechanism of the second joint portion 23 will be described with reference to FIG. FIG. 6 is a diagram illustrating an internal structure of the base portion 20 in the vicinity of the connection portion of the finger portion 21 and an internal structure of the proximal end portion 213 and the second joint portion 23 in the finger portion 21. As shown in FIG. 6, a gear 65, a gear 66, a second motor 52, and a third motor 53 are provided inside the base portion 20. The gear 65 is a gear for rotating the entire finger portion 21, and is connected to the rotation shaft of the base end portion 213. The gear 66 is connected to the rotation shaft of the third motor 53. The gear 65 and the gear 66 are engaged with each other. With such a configuration, when the third motor 53 rotates, the rotational force is transmitted to the rotation shaft of the base end portion 213 via the two gears 65 and 66. As a result, the base end portion 213 is rotationally driven, and accordingly, the entire finger portion 21 is rotationally driven within a range indicated by an arrow in FIG.

Further, a worm wheel 63 and a worm 64 meshed with the worm wheel 63 are provided inside the second joint portion 23. The worm wheel 63 is connected to the rotation shaft of the second finger link part 212 in the second joint part 23. A worm 64 is connected to the rotating shaft of the second motor 52 provided in the base portion 20. With such a configuration, when the second motor 52 is rotationally driven, the rotational force is transmitted to the rotation shaft of the second finger link portion 212 by the worm 64 and the worm wheel 63. As a result, the second finger link part 212 is rotationally driven relative to the base end part 213. Here, FIG. 7 is a diagram showing a movable range of the second joint portion 23 in the finger portion 21 realized by the driving force of the second motor 52. As shown in FIG. 7, the second joint portion 23 is formed to be able to bend and extend. The driving force by the second motor 52 and the driving force by the third motor 53 are configured to be transmitted independently to the operation target.

As shown in FIGS. 4 and 5, in the finger portion 21, one end of the first finger link portion 211 is connected to the other end of the second finger link portion 212. A first joint portion 22 is formed at a connection portion between the first finger link portion 211 and the second finger link portion 212. Here, the drive mechanism of the 1st joint part 22 is demonstrated based on FIG. FIG. 8 is a diagram illustrating an internal structure of the first joint portion 22 and the second finger link portion 212 in the finger portion 21. Two bevel gears 61 and 62 meshing with each other are provided inside the first joint portion 22. One bevel gear 61 is connected to the rotation shaft of the first finger link portion 211 in the first joint portion 22. The other bevel gear 62 is connected to the rotation shaft of the first motor 51 provided inside the second finger link portion 212. With such a configuration, when the first motor 51 is rotationally driven, the rotational force is transmitted to the rotation shaft of the first finger link portion 211 by the two bevel gears 61 and 62. As a result, the first finger link portion 211 is rotationally driven relative to the second finger link portion 212. Here, FIG. 9 is a diagram illustrating a movable range of the first joint portion 22 in the finger portion 21 realized by the driving force of the first motor 51. As shown in FIG. 9, the first joint portion 22 is formed to be able to bend and extend.

Further, as shown in FIGS. 2 and 4, in the present embodiment, the finger portion 21 is based on the first joint portion 22 rather than the first finger link portion 211 on the distal end side of the first joint portion 22. The second finger link part 212 on the part 20 side (base end part 213 side) is longer.

In addition, as shown in FIGS. 2, 4, 5, and 10, in this embodiment, a pressure-sensitive sensor 70 is provided on the distal end side of the first finger link portion 211 of the finger portion 21. The pressure-sensitive sensor 70 is a sensor that detects an external force (pressure) acting on the distal end portion of the first finger link portion 211. Further, as shown in FIG. 4, the pressure-sensitive sensor 70 is a wall surface on the bending direction side of the first joint portion 22 in the first finger link portion 211 (hereinafter also referred to as “bending sidewall surface”) 215. Further, it is provided on both surfaces of the wall surface 216 on the extension direction side (hereinafter also referred to as “extension side wall surface”) 216. Here, in this embodiment, the bent side wall surface 215 on the distal end side of the first finger link portion 211 is formed in a curved surface shape. Therefore, as shown in FIG. 10, a plurality of pressure-sensitive sensors 70 may be arranged side by side along the curved shape on the bent side wall surface 215 on the distal end side of the first finger link portion 211.

<Pedestal part>
Next, 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. 11A. 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. The arm control device 42 and the hand control device 43 form a control device for the gripping system of this embodiment. FIG. 11A is a block diagram illustrating 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 that generate 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 includes a computer having an arithmetic processing device 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 obtained by object information acquired by an object information acquisition unit 430 described later, which is a function unit included in the hand control device 43, and a position information correction unit 435, described later, which is a function unit included in the hand control device 43. By supplying a drive signal from each driver based on the corrected position information of the object 10, the motors provided in the joint portions 30 a, 30 b, 30 c, 30 d, 30 e, and 30 f of the arm mechanism 3 are controlled. Then, the arm controller 420 moves the arm mechanism 3 by controlling each motor, thereby moving the hand mechanism 2 to a predetermined grippable position suitable for gripping the object, for example. In addition, the motors provided in the joint portions 30a, 30b, 30c, 30d, 30e, and 30f of the arm mechanism 3 detect state quantities (such as the rotational position and rotational speed of the rotation shaft of the motor) related to the respective rotational states. 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, the arm control unit 420 servo-controls each motor so that, for example, the hand mechanism 2 moves to a predetermined grippable position based on the motor state quantity input to the motor state quantity acquisition unit 421. The servo control by the arm control unit 420 will be described later.

The hand control device 43 includes a plurality of drivers that generate drive signals for driving the motors provided in the hand mechanism 2 so that the drive signals from the drivers are supplied to the corresponding motors. Composed. The hand control device 43 includes a computer having an arithmetic processing device and a memory. The hand control device 43 includes 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. is 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 that is information regarding an object to be gripped by the hand mechanism 2. Here, the object information includes information on the shape, dimensions, and position of the object, and environmental information around the object (information on objects other than the object existing around the object, for example, , Information on the shape of the container in which the object is stored and the arrangement of the objects in the container). The object information acquisition unit 430 may acquire object information input by the user. When a visual sensor that captures an image including an object is provided, the object information acquisition unit 430 may acquire object information from an image captured by the visual sensor.

Further, 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 corrected by the position information correction unit 435. The first motors 51, the second motors 52, and the third motors 53 that drive the finger portions 21 of the hand mechanism 2 are controlled. For example, the hand control unit 431 controls each of the first mechanisms of the hand mechanism 2 in order to grip the object by the hand mechanism 2 that has been moved to a predetermined grippable position by controlling the arm mechanism 3 by the arm control unit 420. The motor 51, each second motor 52, and each third motor 53 are controlled. In addition, the first motor 51, the second motor 52, and the third motor 53 of the hand mechanism 2 detect state quantities (such as the rotational position and rotational speed of the rotation shaft of the motor) related to the respective rotational states. 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 unit 432, the hand control unit 431, for example, moves each finger so as to hold the object with the plurality of finger parts 21. Servo-control each motor 51,52,53 in the part 21. FIG. Servo control by the hand control unit 431 will be described later.

Furthermore, the hand control device 43 has a sensor information acquisition unit 433. The sensor information acquisition unit 433 receives a detection value of the pressure sensor 70 provided in the first finger link unit 211 of each finger unit 21 of the hand mechanism 2. And when the contact of each finger part 21 to the object is detected by each pressure-sensitive sensor 70, the hand control unit 431, based on the detection signal, each motor 51, 52, 53 in each finger part 21. Can also be controlled. Further, when the contact of each finger 21 with the object is detected by each pressure sensor 70, the contact position deriving unit 434 derives the contact position that is the position where each finger 21 has contacted the object. Is done.

Here, servo control by the arm control unit 420 and the hand control unit 431 will be described with reference to FIG. 11B. FIG. 11B is a conceptual diagram showing a basic structure of a servo control structure formed in each control unit. In FIG. 11B, load devices that are structures such as a motor, a finger unit, and an arm are collectively set as the control target 80. Actually, the arm control unit 420 and the hand control unit 431 have servo control structures corresponding to the arm control unit 420 and the hand control unit 431, respectively. To do. The servo control structure shown in FIG. 11B is formed by executing a predetermined control program in the arm control device 42 and the hand control device 43 which are computers.

The position controller 81 performs, for example, proportional control (P control). Specifically, the speed command is calculated by multiplying the position deviation, which is the deviation between the position command notified from each control device and the detected position, by the position proportional gain Kpp. The position controller 81 has a position proportional gain Kpp as a control parameter in advance. Next, the speed controller 82 performs, for example, proportional-integral control (PI control). Specifically, the speed deviation gain, which is the deviation between the speed command calculated by the position controller 81 and the detected speed, is multiplied by the speed integral gain Kvi, and the sum of the calculation result and the speed deviation is multiplied by the speed proportional gain Kvp. The current command (torque command) is calculated by multiplying. The speed controller 82 has a speed integral gain Kvi and a speed proportional gain Kvp as control parameters in advance. The speed controller 82 may perform P control instead of PI control. In this case, the speed controller 82 has a speed proportional gain Kvp as a control parameter in advance. Next, the current controller 83 generates a command voltage for driving the amplifier 84 based on the current command calculated by the speed controller 82. The amplifier 84 outputs a drive current for driving the motor 2 in accordance with the generated command voltage, whereby the motors mounted on the arm mechanism 3 and the hand mechanism 2 are driven and controlled. The current controller 83 includes a filter (such as a first-order low-pass filter) relating to a current command, and has a cutoff frequency and the like relating to the performance of these filters as control parameters.

The servo control structure shown in FIG. 11B has a current servo loop including a current feedback system having the current controller 83 as a forward element, and further forwards the current feedback system, the speed controller 82, and the control target 80. A speed servo loop including a speed feedback system as an element is included, and a position servo loop including a position feedback system including the speed feedback system and the position controller 81 as forward elements. With the servo control structure configured as described above, each control device servo-controls the motor mounted on the arm mechanism 3 or the hand mechanism 2 so that the finger position of the hand mechanism 2 becomes a desired position. To control.

In FIG. 11A, the arm control device 42 and the hand control device 43 are shown separately as the control devices included in the gripping system, but as an alternative, each functional unit is integrated with both devices. A configuration formed in one control device can also be adopted. Further, even when the control devices included in the gripping system are classified into the arm control device 42 and the hand control device 43, each functional unit shown in FIG. As long as it is formed in the control device, appropriate information can be exchanged between the arm control device 42 and the hand control device 43 as necessary. In addition, a configuration in which a part of each functional unit in the arm control device 42 or the hand control device 43 is formed in a control device separate from the arm control device 42 and the hand control device 43 may be employed. .

<Search operation control>
Here, in the robot arm 1 according to the present embodiment, target object information including position information of the target object is acquired by the target object information acquiring unit 430 that is a functional unit included in the hand control device 43. However, the position information of the object acquired by the object information acquisition unit 430 may include a certain amount of error. For example, when position information of an object is acquired from an image including the object imaged by the visual sensor, an error caused by the 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 desirable to control the arm mechanism 3 and the hand mechanism 2 after grasping the position information of the object with high accuracy. It is.

Therefore, in the robot arm 1 according to the present embodiment, before the arm mechanism 3 and the hand mechanism 2 are controlled to hold the object, the position information of the object is grasped with high accuracy as a preparation stage. Search operation control is performed for the purpose. Hereinafter, search operation control according to the present embodiment will be described with reference to FIGS. 12A to 12C. FIG. 12A to FIG. 12C are views showing the state of the hand mechanism 2 in time series when the search operation control according to the present embodiment is executed. This search operation control is realized by controlling the arm mechanism 3 by the arm control device 42 and controlling the hand mechanism 2 by the hand control device 43.

In the following, each finger part 21 of the hand mechanism 2 is referred to as a first finger part 21A, a second finger part 21B, a third finger part 21C, and a fourth finger part 21D, respectively. Further, in the search operation control, a predetermined finger part of the four finger parts 21 of the hand mechanism 2 is brought into contact with the object. In FIG. 12A to FIG. 12C, an operation in a case where the predetermined finger portion that is brought into contact with the object 10 is the first finger portion 21A is shown. 12A to 12C, for convenience, only the first finger portion 21A, the second finger portion 21B, and the third finger portion 21C in the hand mechanism 2 are illustrated, and the fourth finger portion 21D is illustrated. Is omitted. 12A to 12C show an operation in a case where it is intended to grasp position information of the object 10 in the vertical direction (vertical direction in FIGS. 12A to 12C).

In the search operation control, as shown in FIG. 12A, the form of the hand mechanism 2 is a first approach form in which only the first finger part 21A of the four finger parts 21 is in contact with the object 10. In this state, the hand mechanism 2 is moved in the direction of the white arrow (that is, the downward direction in FIG. 12A) to bring the hand mechanism 2 closer to the object 10. At this time, according to the servo control structure shown in FIG. 11B, the joint portions 30a, 30b, 30c, 30d, and the like of the arm mechanism 3 are moved so that the distal end portion of the first finger portion 21A moves toward the target position in the object 10. The first motor 51, the second motor 52, and the third motor 53 that drive the motors 30e and 30f and the joints of the finger portions 21 of the hand mechanism 2 are arm controlled. Servo-controlled by the device 42 and the hand control device 43. Here, the target position is determined based on the object information acquired by the object information acquisition unit 430. At this time, the target position of the target object 10 when it is assumed that the target object 10 exists at a position corresponding to the position information of the target object 10 included in the target object information acquired by the target object information acquisition unit 430. The position is determined to be inside.

In a state where the form of the hand mechanism 2 is the first approach form, the arm mechanism 3 and the hand mechanism 2 are moved so that the tip of the first finger part 21A moves toward the target position determined as described above. By being controlled, as shown in FIG. 12B, the tip of the first finger 21A comes into contact with the upper surface S1 of the object 10 before the tip of the first finger 21A reaches the target position. In FIG. 12B as well, the white arrow represents the moving direction of the hand mechanism 2. In FIG. 12B, the contact position between the upper surface S1 of the object 10 and the tip of the first finger portion 21A is surrounded by a one-dot chain line. As described above, when the tip of the first finger portion 21A comes into contact with the upper surface S1 of the object 10, the contact is detected by the pressure-sensitive sensor 70 provided on the first finger link portion 211A of the first finger portion 21A. Is done. At this time, the detection value of the pressure sensor 70 is acquired by the sensor information acquisition unit 433. When the pressure sensor 70 of the first finger 21A detects contact between the first finger 21A and the object 10, the contact position deriving unit 434 derives the contact position. Here, the contact position deriving unit 434 is acquired by the state quantity of each motor of the arm mechanism 3 acquired by the motor state quantity acquisition unit 421 of the arm control device 42 and the motor state quantity acquisition unit 432 of the hand control device 43. The contact position between the tip of the first finger portion 21A and the object 10 is derived based on the state quantity of each motor of the hand mechanism 2 to be performed. Then, based on the contact position information related to the contact position derived by the contact position deriving unit 434, the position information correction unit 435 performs the position information (vertical direction position information) of the object 10 acquired by the object information acquiring unit 430. ) Is corrected. For example, when the derived contact position is deviated from the expected contact position from the target position, the position information of the object 10 acquired by the object information acquisition unit 430 is the amount of deviation in the vertical direction. It means that it contains only errors. Therefore, the position information correction unit 435 corrects the position information of the object 10 acquired by the object information acquisition unit 430 so as to eliminate the shift amount. Thereby, the position information of the target object 10 can be grasped with high accuracy.

By performing such search operation control, the position information in the vertical direction of the object 10 is grasped with high accuracy, so that when the object 10 is grasped by the grasping finger portion described later, the grasping finger It is possible to control the vertical position of the portion to a desired position with high accuracy. As a result, the stability of gripping the object 10 by the hand mechanism 2 can be improved. In addition, when a plurality of the same target object 10 are arranged at the same height, if the position information in the vertical direction of one target object 10 is grasped with high accuracy, the other target object 10 can be gripped. The hand mechanism 2 can be controlled using the vertical position information of the one object 10 as the vertical position information regarding the other object 10.

However, when the tip of the first finger portion 21A and the object 10 come into contact with each other, if the collision force acting on them is large, for example, if the object 10 is an object with high hardness, the first finger There is a possibility that the part 21A may be damaged. For example, when the object 10 is an object having low hardness, the object 10 may be damaged. On the other hand, in order to suppress damage to the first finger part 21A or the object 10, if the moving speed of the hand mechanism 2 when the first finger part 21A is brought into contact with the object 10 is reduced, The time required for the search operation control, which is the control in the preparatory stage of the control for gripping the object 10, becomes long. Then, there arises a problem that the tact time required for gripping the object 10 becomes longer as a whole.

Therefore, in the search operation control according to the present embodiment, when the contact between the tip of the first finger 21A and the object 10 is detected by the pressure-sensitive sensor 70 of the first finger 21A, the first finger In relation to servo control of the motor related to the position of the tip of the part 21A, for example, servo control of the first motor 51 that drives the first joint part 22A, at least the position servo loop is invalidated in the servo control structure. Here, disabling at least the position servo loop means that in the control of the hand mechanism 2, at least the position servo loop of the predetermined servo control structure is not operated, in other words, the position of the hand mechanism 2 is This means that the servo control is not performed according to at least the position command. The following two forms can be exemplified as a form of processing for invalidating at least the position servo loop.
(First example) All position servo loops, velocity servo loops, and current servo loops are invalidated. In this case, in the above example, substantially no drive current is supplied to the first motor 51 of the first finger portion 21A. As a result, no driving force is applied from the first motor 51 to the first joint portion 22A of the first finger portion 21A. Therefore, as shown in FIG. 12C, the first joint portion 22 of the first finger portion 21 </ b> A is bent by the force received by the first finger link portion 211 </ b> A of the first finger portion 21 </ b> A from the object 10.
(Second Example) The position servo loop and the velocity servo loop are invalidated, and the current servo loop is maintained in an activated state. In this case, in the above example, control is performed according to a predetermined torque command so that only the torque generated by the first motor 51 of the first finger portion 21A becomes a desired torque. The desired torque in this case is preferably a torque of the first motor 51 before the first finger 21A comes into contact with the object or a torque that does not damage the object and the first finger 21A. Even in the case of the second example, the first joint portion 22 of the first finger portion 21A bends due to the correlation between the desired torque and the force received by the first finger link portion 211A of the first finger portion 21A from the object. It will be.
Note that “at least the position servo loop invalidating process” is not limited to either the first example or the second example described above, but simply “servo invalidating process” or “ This is referred to as “servo invalidation”.

In addition, as shown in FIG. 9, the first joint portion 22 of the finger portion 21 of the hand mechanism 2 according to the present embodiment has a structure that can be bent and extended. Therefore, when the first finger link portion 211A of the first finger portion 21A receives a force from the object 10, the first joint portion 22A of the first finger portion 21A is in either the bending direction or the extension direction. Can also bend. At this time, whether the first joint portion 22A of the first finger portion 21A bends in the bending direction or the extension direction is determined according to the contact direction of the first finger portion 21A with the object 10. Therefore, when the tip of the first finger portion 21A comes into contact with the object 10, the first joint portion 22A of the first finger portion 21A is bent with respect to the object 10 in the first approach form so that the first joint portion 22A bends in a desired direction. The posture of the one finger part 21A may be determined.

As shown in FIG. 12C, when the first joint portion 22A of the first finger portion 21A bends when the tip of the first finger portion 21A comes into contact with the object 10, the collision force acting on these by the contact is applied. Can be reduced. That is, in the search operation control, the first finger 21A or the object is caused by the contact without reducing the moving speed of the hand mechanism 2 when the first finger 21A is brought into contact with the object 10. 10 can be prevented from being damaged. Therefore, according to the search operation control according to the present embodiment, it is possible to grasp the position of the target object 10 with higher accuracy while suppressing an increase in the tact time.

In the search operation control, when the contact between the tip of the first finger 21A and the object 10 is detected by the pressure sensor 70 of the first finger 21A, the hand control device 43 to the arm control device 42. On the other hand, a command signal is transmitted so as to stop the operation of the arm mechanism 3. When the arm control device 42 receives this command signal, the arm control unit 420 moves the hand mechanism 2 toward the object 10 as shown by the white arrow in FIGS. 12A and 12B. Is stopped.

In the above description, the search operation control when grasping the vertical position information of the object has been described as an example, but the same search operation control is also obtained when grasping the position information of the object in the horizontal direction. Can be applied. In this case, the hand mechanism 2 may be brought closer to the object from the horizontal direction in a state where the form of the hand mechanism 2 is the first approach form. In this case as well, when the tip of the first finger portion 21A comes into contact with the object, the same control as the search operation control described above can be executed.

In the present embodiment, the pressure-sensitive sensor 70 may be any known type of sensor such as a piezoelectric type, a strain gauge type, or a capacitance type. In this embodiment, the pressure-sensitive sensor 70 corresponds to a “contact detection unit” according to the present invention. Further, when an external force (pressure) acts on the distal 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 a “contact detection unit” according to the present invention, instead of the pressure sensor 70.

Further, in the search operation control described above, the motor subjected to the servo invalidation process when the contact between the tip of the first finger 21A and the object 10 is detected by the pressure sensor 70 of the first finger 21A is as follows. It is not necessarily limited to the first motor 51. That is, the servo invalidation process is performed on the second motor 52 that drives the second joint portion 22B of the first finger portion 21A when contact between the tip of the first finger portion 21A and the object 10 is detected. Also good. In this case, the second joint portion 22B of the first finger portion 21A bends when the contact between the distal end portion of the first finger portion 21A and the object 10 is detected. Therefore, even in this case, it is possible to reduce the collision force acting on the first finger portion 21A and the object due to the contact. Further, as another method, if the arm mechanism 3 can maintain a safe state, servo invalidation processing can be performed on any motor incorporated in the arm mechanism 3.

In the search operation control, the part of the finger part that is brought into contact with the object (that is, the “predetermined contact part” according to the present invention) does not necessarily have to be the tip part of the finger part. For example, as described above, when the first finger portion 21A of the hand mechanism 2 is a predetermined finger portion that is brought into contact with the object, the second finger link portion 21B in the first finger portion 21A may be brought into contact with the object. Good. However, in this case, it is necessary that the first approach form in the search operation control is such that only the second finger link part 21B in the first finger part 21A contacts the object. Furthermore, when detecting contact with an object using a pressure sensor, it is necessary to provide a pressure sensor in the second finger link portion 21B. In the search operation control, servo invalidation processing is performed on the second motor 52 that drives the second joint portion 22B of the first finger portion 21A when contact with the object of the second finger link portion 21B is detected. Apply. Thereby, when the 2nd finger link part 21B of 21 A of 1st finger parts contact a target object, the 2nd joint part 22B of this 1st finger part 21A will bend. Therefore, even in this case, it is possible to reduce the collision force acting on the first finger portion 21A and the object due to the contact.

<Positioning control>
Here, when the object is gripped by the hand mechanism 2, it is necessary to sandwich the object by at least two fingers 21. In the following, a finger part used to pinch the object 10 when the object is gripped by the hand mechanism 2 may be referred to as a “gripping finger part”. According to the hand mechanism 2, the object can be gripped by using two of the four finger portions 21 as gripping finger portions, and three of the four finger portions 21 can be gripped. The object can be grasped using the fingers of the fingers as gripping fingers, and the object can be grasped using all of the four fingers 21 as the fingers of grasping.

In order to grip an object with the gripping fingers in the hand mechanism 2, before the object is sandwiched by the gripping fingers, the predetermined gripping location on the object has at least two gripping fingers. It is necessary to position the hand mechanism 2 at a predetermined grippable position that is located between the distal ends of the two parts. In addition, the predetermined holding | grip location here is a part which contacts the finger part for holding in a target object. In the following, when the case where the object is a cube is described, the predetermined gripping portion will be described as a predetermined gripping surface which is a surface with which a gripping finger part is brought into contact among a plurality of surfaces forming the cube.

Hereinafter, in this embodiment, the hand mechanism 2 is positioned at a predetermined grippable position so that a predetermined gripping surface of the object is positioned between the tips of the two gripping fingers in the hand mechanism 2. Positioning operation control for this will be described with reference to FIGS. 13A to 13E. FIG. 13A to FIG. 13E are views showing the state of the hand mechanism 2 in time series when the positioning operation control according to the present embodiment is executed. This positioning operation control is realized by controlling the arm mechanism 3 by the arm control device 42 and controlling the hand mechanism 2 by the hand control device 43 in accordance with the servo control structure shown in FIG. 11B.

13A to 13E, the second finger portion 21B and the third finger portion 21C in the hand mechanism 2 are gripping finger portions, and the surface S2 of the object 10 (the surface on the left side in FIGS. 13A to 13E). ) And the surface S3 (the surface on the right side in FIGS. 13A to 13E) as the predetermined gripping surface. 13A to 13E, for convenience, only the first finger portion 21A, the second finger portion 21B, and the third finger portion 21C in the hand mechanism 2 are illustrated, and the fourth finger portion 21D is illustrated. Is omitted.

In the positioning operation control, as shown in FIG. 13A, the distal end portions of the second finger portion 21B and the third finger portion 21C that use the form of the hand mechanism 2 as gripping finger portions in the gripping of the object 10 this time. A surface that is a predetermined gripping surface of the object 10, with a distance between the distal end portion of the first finger link portion 211 </ b> B of the second finger portion 21 </ b> B and the distal end portion of the first finger link portion 211 </ b> C of the third finger portion 21 </ b> C. The hand mechanism 2 is brought close to the object 10 in the state of the second approach form that is widened to a predetermined initial interval df that is larger than the width dt between S2 and the surface S3. 13A indicates the direction in which the hand mechanism 2 moves.

Here, in the second approach form, when the object 10 is gripped by the second finger part 21B and the third finger part 21C of the hand mechanism 2, the first finger part 21A, which is the other finger part, and the first finger part 21A The four-finger portion 21D is set as a form that does not contact the object 10. Such a 2nd approach form is determined based on the information regarding the shape and dimension of the target object 10 acquired by the target object information acquisition unit 430. At this time, the predetermined initial interval df between the distal end portion of the second finger portion 21B and the distal end portion of the third finger portion 21C in the second approach form is the object 10 acquired by the object information acquisition unit 430. It is determined based on the width dt between the surface S2 and the surface S3.

In the positioning operation control, each motor and hand of the arm mechanism 3 are moved to move the hand mechanism 2 to a predetermined grippable position in a state where the form of the hand mechanism 2 is the second approach form as described above. Each motor in each finger portion 21 of the mechanism 2 is servo-controlled by an arm control device 42 and a hand control device 43, respectively. Note that the predetermined grippable position in this case is a position where the surface S2 and the surface S3 of the object 10 are located between the distal end portion of the second finger portion 21B and the distal end portion of the third finger portion 21C. It is.

At this time, the position information (horizontal position information) of the object 10 acquired by the object information acquisition unit 430 and the position information (vertical position information) of the object 10 corrected by the position information correction unit 435 are included. Based on this, the arm mechanism 3 is controlled by the arm control device 42, and the hand mechanism 2 is controlled by the hand control device 43. Here, the position information in the vertical direction with respect to the object 10 is corrected by the position information correction unit 435 by performing the search operation control described above. That is, the vertical position of the object 10 can be grasped with high accuracy. However, there is a possibility that the horizontal position information about the object 10 still contains some error. Therefore, in the state where the form of the hand mechanism 2 is the second approach form, when the hand mechanism 2 is brought close to the object 10 with the predetermined grippable position as the target hand position, as shown in FIG. Before the position of the hand mechanism 2 reaches a predetermined grippable position, one gripping finger portion (second finger portion 21B in FIG. 13B) may come into contact with the upper surface S1 of the object 10. In FIG. 13B, the white arrow represents the moving direction of the hand mechanism 2. In FIG. 13B, the contact position between the upper surface S1 of the object 10 and the tip of the second finger portion 21B is surrounded by an alternate long and short dash line. As described above, when the tip of the second finger portion 21B comes into contact with the upper surface S1 of the object 10, the contact is detected by the pressure-sensitive sensor 70 provided on the first finger link portion 211A of the second finger portion 21B. Is done. Further, in order to suppress damage to the finger part 21 or the object 10 due to contact between the finger part 21 of the hand mechanism 2 and the object 10 in such positioning operation control, the hand in the positioning operation control is controlled. The moving speed of the mechanism 2 may be smaller than the moving speed of the hand mechanism 2 in the search operation control described above.

Therefore, in the positioning operation control according to the present embodiment, when it is detected that one of the gripping fingers touches the object 10 before the position of the hand mechanism 2 reaches the predetermined grippable position. As shown in FIG. 13C, the horizontal position of the hand mechanism 2 is corrected. At this time, the position of the hand mechanism 2 in the horizontal direction is corrected based on which gripping finger portion is in contact with the object 10. Specifically, in FIG. 13C, the hand mechanism 2 is moved to the second finger portion 21B side that is in contact with the upper surface S1 of the object 10. At this time, the interval between the distal end portion of the second finger portion 21B and the distal end portion of the third finger portion 21C is maintained at a predetermined initial interval df. In FIG. 13C, the white arrow indicates the moving direction of the hand mechanism 2.

As shown in FIG. 13C, by moving the hand mechanism 2 to the second finger portion 21B side in contact with the object 10, the horizontal position of the hand mechanism 2 is changed between the second finger portion 21B and the third finger. It can correct so that the target object 10 may be located under the part 21C. Then, after correcting the horizontal position of the hand mechanism 2 in this manner, as shown in FIG. 13D, the hand mechanism 2 is again moved downward (that is, moved again toward a predetermined grippable position). ). In FIG. 13D, the white arrow represents the moving direction of the hand mechanism 2. As a result, the hand mechanism 2 can reach a predetermined grippable position. That is, the surface S2 and the surface S3 of the object 10 can be positioned between the distal end portion of the second finger portion 21B and the distal end portion of the third finger portion 21C. Note that the position in the vertical direction at the predetermined grippable position is naturally determined in advance as a position suitable for gripping the object 10.

Then, after setting the position of the hand mechanism 2 to a predetermined grippable position as shown in FIG. 13D, as shown in FIG. 13E, between the tip part of the second finger part 21B and the tip part of the third finger part 21C. The second finger portion 21B and the third finger portion 21C are controlled so that the interval is smaller than a predetermined initial interval df. In FIG. 13E, the white arrow represents the moving direction of the distal end portion of the second finger portion 21B and the distal end portion of the third finger portion 21C. As a result, the tip of the second finger 21B is brought into contact with the surface S2 of the object 10, and the tip of the third finger 21C is brought into contact with the surface S3 of the object 10, so that these gripping fingers 21B, The object 10 is gripped by 21C.

Here, as described above, the finger parts functioning as the gripping finger parts in the hand mechanism 2 according to the present embodiment are not limited to the second finger part 21B and the third finger part 21C, and all the finger parts 21 are gripped. Can function as a finger part. In addition, three finger portions of the four finger portions 21 of the hand mechanism 2 may be used as gripping finger portions, or all four finger portions may be used as gripping finger portions. And if the finger part used as a gripping finger part differs, the 2nd approach form of the hand mechanism 2 at the time of performing positioning operation control will also become a different form.

Hereinafter, an example of position correction of the hand mechanism 2 in the positioning operation control when the gripping finger portion and the second approach form are different from the cases illustrated in FIGS. 13A to 13E will be described based on FIGS. 14 and 15. Also in the modified example, each finger part of the hand mechanism 2 and the arm mechanism 3 are controlled according to the servo control structure shown in FIG. 11B. FIGS. 14A and 14B show gripping finger portions and objects in the case where the second finger portion 21B, the third finger portion 21C, and the fourth finger portion 21D of the hand mechanism 2 are gripping finger portions. 10 is a diagram showing a positional relationship with 10 in the horizontal direction. 14 (a) and 14 (b) show that when the object 10 is gripped, the second finger part 21B and the fourth finger part 21D are brought into contact with the surface S2 of the object 10, and the third finger part. The form in the case of bringing 21C into contact with the surface S3 of the object 10 is shown. In the second approach form in this case, between the tip of the second finger 21B and the tip of the third finger 21C and between the tip of the fourth finger 21D and the tip of the third finger 21C. A predetermined initial interval between them is set so that the surface S2 and the surface S3 of the object 10 are located in any of the above.

FIG. 14A shows that the second finger portion 21B and the fourth finger portion 21D are moved when the hand mechanism 2 is brought closer to the object 10 in the state where the second approach form is as described above. The state which contacted the upper surface S1 of this target object 10 is shown. In this case, in the positioning operation control according to the present embodiment, as shown in FIG. 14B, the hand mechanism 2 is moved to the second finger portion 21B and the fourth finger portion 21D that are in contact with the object 10. In FIG. 14B, the white arrow indicates the moving direction of the hand mechanism 2. As shown in FIG. 14 (b), by moving the hand mechanism 2 to the second finger portion 21B and the fourth finger portion 21D side in contact with the object 10, the horizontal position of the hand mechanism 2 is It can correct so that the target object 10 may be located between the 2nd finger part 21B and the 3rd finger part 21C, and the downward direction between this 4th finger part 21D and the 3rd finger part 21C. Then, after correcting the horizontal position of the hand mechanism 2 to such a position, the hand mechanism 2 is moved downward again to change the position of the hand mechanism 2 to the tip of the second finger portion 21B. Predetermined grip where the surface S2 and the surface S3 of the object 10 are located between the tip of the third finger 21C and between the tip of the fourth finger 21D and the tip of the third finger 21C. It can be a possible position.

FIGS. 15A and 15B show the positional relationship in the horizontal direction between each gripping finger portion and the object 10 when all the four finger portions 21 of the hand mechanism 2 are gripping finger portions. FIG. 15 (a) and 15 (b), when grasping the object 10, the second finger portion 21B is brought into contact with the surface S2 of the object 10, and the third finger portion 21C is brought into contact with the object 10. A mode in which the first finger 21A is brought into contact with the surface S4 of the object 10 and the fourth finger 21D is brought into contact with the surface S5 of the object 10 is shown. In the second approach form in this case, the surface S2 and the surface S3 of the object 10 are positioned between the tip of the second finger 21B and the tip of the third finger 21C so that the surface S2 and the surface S3 of the object 10 are positioned between them. An initial interval is set. Moreover, the predetermined | prescribed initial space | interval between these is set so that the surface S4 and surface S5 of the target object 10 may be located between the front-end | tip part of 21 A of 1st fingers, and the front-end | tip part of 4th finger part 21D. .

FIG. 15A shows that when the hand mechanism 2 is brought close to the object 10 with the second approach form as described above, the first finger part 21A and the second finger part 21B are The state which contacted the upper surface S1 of this target object 10 is shown. In this case, in the positioning operation control according to the present embodiment, the second finger portion 21B and the third finger portion 21C are in the direction of the second finger portion 21B in contact with the object 10, and the first finger portion 21A. And for the fourth finger portion 21D, the direction of the first finger portion 21A in contact with the object 10, the direction of the white arrow in FIG. 15B (that is, the upper left diagonal in FIG. 15B) The hand mechanism 2 is moved in the direction toward As shown in FIG. 15B, by moving the hand mechanism 2 to the first finger portion 21A side and the second finger portion 21B side in contact with the object 10, the horizontal position of the hand mechanism 2 is It can correct | amend so that the target object 10 may be located between this 2nd finger | toe part 21B and the 3rd finger | toe part 21C, and below between this 1st finger | toe part 21A and 4th finger | toe part 21D. Then, after correcting the horizontal position of the hand mechanism 2 to such a position, the hand mechanism 2 is moved downward again to change the position of the hand mechanism 2 to the tip of the second finger portion 21B. The surface S2 and the surface S3 of the object 10 are located between the tip of the third finger 21C, and the object 10 is between the tip of the first finger 21A and the tip of the fourth finger 21D. The predetermined grippable position where the surface S4 and the surface S5 are located can be set.

<Gripping movement control>
When the object is gripped by the hand mechanism 2, after the position of the hand mechanism 2 is controlled to the above-described predetermined grippable position, for example, as shown in FIG. 21B and the third finger portion 21C) are brought into contact with predetermined gripping portions (surfaces S2 and S3 which are predetermined gripping surfaces in FIG. 13E) of the object. Then, the object is sandwiched by the gripping finger part by pressing the object with the gripping finger part in contact with the object. Hereinafter, in the present embodiment, gripping operation control for sandwiching an object by a gripping finger portion of the hand mechanism 2 located at a predetermined grippable position will be described with reference to FIG. FIG. 16 shows the positional relationship in the horizontal direction between the gripping fingers of the hand mechanism 2 and the object 10 when the gripping motion control according to this embodiment is executed in time series from (a) to (d). It is the figure shown along. This gripping operation control is realized by servo-controlling each motor in each finger portion 21 of the hand mechanism 2 by the hand control device 43. In FIG. 16, the second finger portion 21B, the third finger portion 21C, and the fourth finger portion 21D of the hand mechanism 2 are used as gripping finger portions, and the second finger portion 21B and the fourth finger portion 21D are the object 10. In addition, the third finger 21C is brought into contact with the surface S3 of the object 10 while being brought into contact with the surface S2, and the object 10 is gripped. In FIG. 16, the white arrow represents the moving direction of the tip of each gripping finger portion 21A, 21B, 21C.

As shown in FIG. 16A, in the gripping operation control, the hand mechanism 2 is controlled so that the tip portions of the gripping finger portions 21A, 21B, and 21C move toward a predetermined gripping surface of the object 10. To do. That is, the tip of the second finger 21B and the tip of the fourth finger 21D move toward the surface S2 of the object 10, and the tip of the third finger 21C is on the surface S3 of the object 10. Move toward. At this time, the tip portions of the gripping finger portions 21B, 21C, and 21D do not necessarily reach the predetermined gripping surfaces corresponding to the objects 10 at the same time. That is, the tip portions of the gripping finger portions 21B, 21C, and 21D do not necessarily contact the object 10 at the same timing. For example, in FIG. 16, the second finger portion 21 </ b> B first contacts the surface S <b> 2 of the object 10 in (b), and then the fourth finger portion 21 </ b> D contacts the surface S <b> 2 of the object 10 in (c). Finally, in (d), the third finger portion 21 </ b> C contacts the surface S <b> 3 of the object 10.

Here, when the object 10 is gripped by the gripping finger part, the object 10 is pressed by the outer gripping finger part in contact with a predetermined gripping surface. That is, even after the gripping finger part contacts the object 10, it is necessary to operate each motor of the gripping finger part in order to press the object 10. At this time, when the contact timings of the gripping finger portions 21B, 21C, and 21D to the object 10 are different as shown in FIG. 16, the second finger portion 21B is temporarily shown in FIG. When only the operation of each motor of the second finger 21B is continued to press the object 10 by the second finger 21B when only the object 10 contacts the object 10, the second finger 21B gives it. There is a possibility that the position of the object 10 is moved or the posture thereof is changed by the force to be applied. That is, in the middle of the gripping operation control, before all the gripping finger parts come into contact with the object 10, the gripping finger parts that have come into contact with the target object 10 before the other gripping finger parts are used. When force is applied to the object 10, the position or posture of the object 10 may change. As described above, when the position or posture of the object 10 changes during the gripping operation control, the gripping stability of the object 10 by the hand mechanism 2 may be reduced.

Therefore, according to the gripping operation control according to the present embodiment, as shown in FIGS. 16B, 16C, and 16D, the object is detected by the pressure sensor 70 provided at the tip of each gripping finger. When contact with an object is detected, the operation of each motor in each gripping finger is temporarily stopped. That is, as shown in FIG. 16B, the operation of each motor of the second finger portion 21B is stopped when the second finger portion 21B comes into contact with the surface S2 of the object 10. As a result, no force is applied to the object 10 from the second finger portion 21B. However, the operation of the motors of the third finger portion 21C and the fourth finger portion 21D, which are other gripping finger portions, is naturally continued even after the second finger portion 21B comes into contact with the object 10. For this reason, as indicated by a hollow arrow in FIG. 16B, the tip of the third finger portion 21C and the tip of the fourth finger portion 21D further approach the object 10.

And as shown in FIG.16 (c), when the 4th finger part 21D contacts the surface S2 of the target object 10 following the 2nd finger part 21B, the operation | movement of the motor of this 4th finger part 21D is stopped. As a result, no force is applied to the object 10 from the fourth finger portion 21D. However, as indicated by the white arrow in FIG. 16C, the operation of each motor of the third finger portion 21C is naturally continued even after the fourth finger portion 21D comes into contact with the object 10. Therefore, the tip part of the third finger part 21 </ b> C further approaches the object 10. Thereafter, as shown in FIG. 16D, when the third finger portion 21 </ b> C comes into contact with the object 10, all the gripping finger portions 21 </ b> B, 21 </ b> C, and 21 </ b> D are in contact with the object 10. In the gripping operation control according to the present embodiment, after all the gripping finger parts 21B, 21C, and 21D are in contact with the object 10, the gripping part 21B, 21C, By operating each of the 21D motors, the object 10 is pressed by these gripping fingers, and the object 10 is gripped. According to such gripping operation control, the position or posture of the object 10 is suppressed from changing during the gripping operation control. Therefore, it is possible to suppress a decrease in the gripping stability of the object 10 by the hand mechanism 2.

In the gripping operation control, it is not always necessary to operate the motors of all the gripping finger portions again after all the gripping finger portions are in contact with the object 10. For example, the object 10 may be pressed by the gripping finger portion by operating only the motor of one gripping finger portion in a state where all the gripping finger portions are in contact with the object 10. Even in this case, the object 10 can be supported by the other gripping fingers whose motor operation is stopped, so that the object 10 can be gripped. However, as shown in FIG. 16 (d), when the object is pressed by all the gripping finger parts by operating the motors of all the gripping finger parts again, the object 10 is more A pressing force can be applied in a well-balanced manner. Therefore, it is possible to suppress the moment from being generated with respect to the object 10. Therefore, the stability of gripping the object 10 by the hand mechanism 2 can be further improved.

Even in the gripping finger portion in the positioning operation control and the gripping operation control described above, the portion to be brought into contact with the object (that is, the “predetermined contact portion” according to the present invention) is not necessarily the tip portion of the finger portion. Good. However, when the contact with the object is detected by the pressure sensor, it is necessary to provide the pressure sensor at a portion of the gripping finger portion to be brought into contact with the object.

<Search operation control flow>
Next, the flow of the search operation control described above will be described based on the flowchart shown in FIG. This search operation control flow is realized by executing a predetermined control program in the arm control device 42 and the hand control device 43. In this flow, first, in S101, object information about the object to be grasped this time is acquired by the object information acquisition unit 430.

Next, in S102, a target position in the current search operation control is determined based on the object information acquired by the object information acquisition unit 430 in S101. Next, in S103, the first approach mode of the hand mechanism 2 in the current search operation control is determined based on the object information acquired by the object information acquisition unit 430 in S101. Here, as described above, in the search operation control, a predetermined finger portion of the four finger portions 21 of the hand mechanism 2 is brought into contact with the object. At this time, in the first approach form determined in S103, the finger part selected as the predetermined finger part to be brought into contact with the object may be referred to as “search finger part” below. Next, in S104, the form of the hand mechanism 2 is controlled to the first approach form determined in S103. Note that the processing from S101 to S104 is executed by the hand control unit 431.

Next, in S105, the arm mechanism 3 is controlled by the arm control unit 420 so that the tip of the finger part for search of the hand mechanism 2 is directed to the target position determined in S102. Move. At this time, the hand control unit 431 maintains the form of the hand mechanism 2 in the first approach form. Next, in S106, it is determined whether or not contact with the object 10 is detected by the pressure-sensitive sensor 70 of the search finger before the tip of the search finger reaches the target position. Note that the process of S106 is executed by the sensor information acquisition unit 433. If a negative determination is made in S106, that is, if the search finger has not yet contacted the object, the process of S105 is continued.

On the other hand, if an affirmative determination is made in S106, then in S107, the hand control unit 431 performs servo invalidation processing on the first motor 51 of the search finger unit. Thereby, for example, as shown in FIG. 12C, the first joint portion 22 of the search finger portion is bent. Furthermore, in S <b> 107, the arm control unit 420 stops the operation of the arm mechanism 3 by transmitting a command signal from the hand control device 43 to the arm control device 42.

Next, in S108, the contact position deriving unit 434 derives the contact position when contact with the object 10 is detected by the pressure sensitive sensor 70 of the search finger. Next, in S109, the position information of the object acquired by the object information acquisition unit 430 is corrected by the position information correction unit 435 based on the contact position information regarding the contact position derived by the contact position deriving unit 434 in S108. Is done.

In the flowchart shown in FIG. 17, the contact position is derived in S108, and the position information of the object is corrected based on the contact position in S109. However, the processing of S101 to S107 is not included without including these processes. The search operation control according to the above flow is also included in the present embodiment. In such search operation control, when the search finger touches the object, servo invalidation processing is performed on the first motor 51 of the search finger and the operation of the arm mechanism 3 is stopped. .

<Flow of positioning operation control and gripping operation control>
Next, the flow of the positioning operation control and the gripping operation control described above will be described based on the flowcharts shown in FIGS. This flow of positioning operation control and gripping operation control is also realized by executing predetermined control programs in the arm control device 42 and the hand control device 43. Further, the control along this flow is executed when the same object is gripped by the hand mechanism 2 after the search operation control is executed by the control flow shown in FIG.

In this flow, as shown in FIG. 18 and FIG. 19, each process related to the positioning operation control is executed in S201 to S211. Here, first, in S201, the second approach mode of the hand mechanism 2 in the current positioning operation control is determined. At this time, it is determined which finger part 21 in the hand mechanism 2 is to be the current gripping finger part. Next, in S202, a predetermined grippable position in the current positioning operation control is determined. In the present embodiment, the processing of S201 and S202 is performed by performing the search operation control according to the control flow shown in FIG. 17, so that the object information and position information correction unit acquired by the object information acquisition unit 430 is performed. This is executed by the hand control unit 431 based on the position information of the object corrected by 435. However, when the search operation control is not executed, the second approach form and the predetermined grippable position of the hand mechanism 2 are determined based only on the object information acquired by the object information acquisition unit 430.

Next, in S203, the hand control unit 431 controls the form of the hand mechanism 2 to the second approach form determined in S202. Next, in S204, the arm control unit 420 moves the arm so that the hand mechanism 2 whose form is maintained in the second approach form by the hand control unit 431 is directed to the predetermined grippable position determined in S202. The hand mechanism 2 is moved by controlling the mechanism 3. Next, in S205, it is determined whether or not contact with the object is detected by the pressure-sensitive sensor 70 of any of the gripping fingers. Note that the process of S205 is executed by the sensor information acquisition unit 433. If a negative determination is made in S205, then in S206, the hand control unit 431 determines whether or not the hand mechanism 2 has reached the predetermined grippable position determined in S202. At this time, the current position of the hand mechanism 2 is the state quantity of each motor of the arm mechanism 3 acquired by the motor state quantity acquisition unit 421 of the arm control apparatus 42 and the motor state quantity of the hand control apparatus 43. It is derived based on the state quantity of each motor of the hand mechanism 2 acquired by the acquisition unit 432. If an affirmative determination is made in S206, the current positioning operation control has been completed. In this case, processing subsequent to S212 is executed. On the other hand, if a negative determination is made in S206, that is, if the hand mechanism 2 has not yet reached the predetermined grippable position, the process of S204 is executed again.

In addition, when an affirmative determination is made in S205, it can be determined that any of the gripping fingers touches the object before the hand mechanism 2 reaches the predetermined grippable position. In this case, as shown in FIG. 19, the operation of the arm mechanism 3 is temporarily stopped by the arm controller 420 in S207. Next, the process of S208 is executed. At this time, the number of gripping finger portions that are in contact with the object is not limited to one, and a plurality of gripping finger portions may be in contact with the object. In addition, if the error of the object information acquired by the object information acquisition unit 430 is large, all the gripping fingers may come into contact with the object. If the number of gripping finger portions in contact with the object is too large, even if the position of the hand mechanism 2 in the positioning operation control as described above is corrected, the hand mechanism 2 is brought to a predetermined grippable position. Sometimes it cannot be reached. Therefore, in S208, it is determined whether or not the number of gripping finger portions that have contacted the object is smaller than a predetermined number. Here, even when the position of the hand mechanism 2 in the positioning operation control as described above is corrected when the number of gripping finger portions that are in contact with the object is greater than or equal to the predetermined number, the hand mechanism 2 is a number by which it can be determined that 2 cannot reach the predetermined grippable position. Such a predetermined number is set according to the number of gripping fingers in the second approach configuration of the hand mechanism 2 in the current positioning operation control determined in S201.

If a negative determination is made in S208, that is, if the number of gripping finger portions that have touched the object is greater than or equal to a predetermined number, then in S211, the second approach configuration of the hand mechanism 2 is changed. In this case, a new second approach configuration is determined so that the hand mechanism 2 can reach a predetermined grippable position in consideration of the contact position of each gripping finger that has contacted the object. . Note that the processing of S208 and S209 is executed by the hand control unit 431. Then, after the second gripping form of the hand mechanism 2 is changed in S211, the process of S203 is executed again, and the form of the hand mechanism 2 is controlled to the newly determined second approach form. Thereafter, the processing after S204 is executed.

On the other hand, if an affirmative determination is made in S208, then in S209, the position of the hand mechanism 2 in the positioning operation control described above is corrected. That is, in the state where the form of the hand mechanism 2 is maintained in the second approach form at this time, the hand mechanism 2 is in the direction of the gripping finger portion side in contact with the object (for example, FIG. 13C, FIG. 14, FIG. 15 in the direction indicated by the white arrow). Note that the processing of S209 is executed by the hand control unit 431 and the arm control unit 420.

Then, next to S209, in S210, it is determined whether or not the gripping finger has been separated from the object. The process of S201 is executed by the sensor information acquisition unit 433 based on the detection value of the pressure sensor 70 of the gripping finger that has been in contact with the object. If a negative determination is made in S210, the process of S209 is executed again. That is, the amount of movement of the hand mechanism 2 in the direction of the gripping finger side that is in contact with the object is increased. Thereafter, the process of S210 is executed again. On the other hand, when an affirmative determination is made in S210, the process of S204 is executed again. That is, the movement of the hand mechanism 2 toward the predetermined grippable position is resumed.

Then, as shown in FIG. 20, each processing related to the gripping operation control is executed after S212. In S212, in the hand mechanism 2 in a state where the current positioning operation control is completed, each motor in the gripping finger portion that is not in contact with the object is operated. As a result, the distal end portion of each gripping finger portion moves toward a predetermined gripping surface of the object corresponding to the tip portion. Immediately after an affirmative determination is made in S206, that is, immediately after the current positioning operation control is completed, all the gripping finger portions are not in contact with a predetermined gripping surface of the object. Therefore, in this case, in S212, each motor in all the gripping fingers is operated.

Then, in step S213, it is determined whether or not contact with the object is detected by the pressure-sensitive sensor 70 of each gripping finger. If a negative determination is made in S213, the process of S212 is continued. On the other hand, if an affirmative determination is made in S213, then in S214, the operation of each motor in the gripping finger portion where contact with the object is detected by the pressure sensor 70 is stopped. Next, in S215, it is determined whether or not contact with the object has been detected for all of the gripping fingers in the current grasping of the object. If a negative determination is made in S215, the process of S212 is executed again. Thereby, the operation of each motor in the gripping finger portion that is not in contact with the object is continued. However, even in this case, the state in which the operation of each motor is stopped is maintained for the gripping finger portion in which contact with the object is detected. Then, when the processes from S212 to S215 are repeated until all the gripping finger portions come into contact with the predetermined gripping surface of the target object, when the pressure sensor 70 detects the contact with the target object 10. Thus, the operation of each motor in each gripping finger portion is temporarily stopped. Note that the processing of S212 and S214 is executed by the hand control unit 431. Further, the processing of S213 and S215 is executed by the sensor information acquisition unit 433.

If an affirmative determination is made in S215, then the process of S216 is executed. In S216, the contact position deriving unit 434 derives the contact position of each gripping finger on the object. Next, in S217, it is determined whether or not the correction of the contact position of each gripping finger part is necessary based on the contact position information regarding the contact position of each gripping finger part in the object derived in S216. Even when all of the gripping finger portions are in contact with the target object through a series of positioning control and gripping operation control so far, the contact position of each gripping finger portion on the target object is the target object. In some cases, the position is not suitable for gripping. That is, when the object is pressed by each gripping finger while the contact position of each gripping finger on the object is set to the position at the time when the process of S217 is performed, a moment or the like is applied to the object. It may be expected that it is difficult to stably hold the object because of the action. In such a case, a negative determination is made in S217. If a negative determination is made in S217, then in S221, the contact position of at least one gripping finger portion of the plurality of gripping finger portions with the object is changed. At this time, the contact position of the at least one gripping finger portion with the target is changed to a position where it is assumed that the target can be gripped more stably.

Here, in S221, by operating each motor of at least one gripping finger, the position of contact with the object may be changed by moving the at least one finger portion. When the posture of the object 10 can be changed, at least one gripping finger is separated from the object and the object is pressed by another gripping finger part. The posture may be changed. Then, the posture of the object may be changed until the gripping finger once separated from the object comes into contact with the object again. And as a result, you may change the contact position to the target object of the grasping finger part once separated from the target object. In this manner, after the contact position of at least one gripping finger part with the object is changed in S221, the process of S216 is executed again. As described above, when a negative determination is made in S217, it is possible to more stably hold the target object by changing the contact position of at least one gripping finger portion with the target object. .

On the other hand, if an affirmative determination is made in S217, then in S218, the motors of all the gripping finger portions are operated again in a state where all the gripping finger portions are in contact with the object. As a result, the object is pressed by each gripping finger. As described above, in S218, it is not always necessary to operate all the gripping finger motors. That is, the object 10 may be pressed by the gripping finger portion by operating only the motor of the gripping finger portion.

Next, in S219, it is determined whether or not the grasping of the object by the grasping finger unit is completed. Whether or not gripping of the object by the gripping finger unit is completed is based on the position of the tip of each gripping finger unit or the pressure detected by the pressure-sensitive sensor 70 of each gripping finger unit. Can be determined. If a negative determination is made in S219, the processing in S218 is continued. On the other hand, if an affirmative determination is made in S219, then in S220, the operation of each motor of each gripping finger is stopped. As a result, the position of the tip of each gripping finger at that time or the pressure applied to the object by each gripping finger is maintained. And this grip operation control is completed.

<Modification>
Although the search operation control and the positioning operation control are executed separately according to the above embodiment, these controls may be executed simultaneously. In this case, the hand mechanism 2 is brought close to the object in a state where the form of the hand mechanism 2 is the second approach form in the positioning operation control. At this time, when contact with the target object is detected by the pressure-sensitive sensor 70 of any one of the gripping finger parts, the contact position between the gripping finger part and the target object is derived. Furthermore, the position information of the target acquired by the target information acquisition unit 430 is corrected based on the derived contact position information regarding the contact position between the gripping finger and the target. Even in such a case, the position information of the object can be grasped with high accuracy. Even in such a case, the servo invalidation process is performed on the first motor 51 of the gripping finger when the pressure-sensitive sensor 70 of any gripping finger detects contact with the object. Apply. As a result, it is possible to prevent the gripping finger part or the object from being damaged due to the contact between the gripping finger part and the object.

In the above embodiment, the number of the finger portions 21 provided in the hand mechanism 2 is four. However, if the hand mechanism 2 has at least two finger portions, a series of searches as described above are performed. Operation control, positioning operation control, and gripping control can be executed.

DESCRIPTION OF SYMBOLS 1 ... Robot arm, 2 ... Hand mechanism, 20 ... Base part, 21 ... Finger part, 22 ... 1st joint part, 23 ... 2nd joint part, 211 ... 1st finger link part, 212 ... 2nd finger link part, 213 ... Base end part, 3 ... Arm mechanism, 30a ... 1st joint part, 30b ... 2nd joint part, 30c ... 3rd joint part, 30d ... 4th joint part, 30e ... 5th joint part, 30f ... 6th joint part, 31 ... 1st arm link part, 32 ... 1st 2 arm link part, 33 ... 3rd arm link part, 34 ... 4th arm link part, 35 ... 5th arm link part, 36 ... connecting 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. 53 ... 3rd motor, 61, 62 ... Bevel gear, 63 ... Worm wheel, 64 ... Worm, 65, 66 ... Gear, 70 ... Pressure sensor

Claims (10)

1. An arm mechanism;
   A hand mechanism attached to the arm mechanism and gripping an object by a plurality of fingers;
   An acquisition unit for acquiring position information of the object;
   In a gripping system comprising: a control device that controls the position of the hand mechanism by controlling the arm mechanism and the hand mechanism according to a predetermined servo control structure for controlling the position of the hand mechanism with respect to the object. ,
   The hand mechanism is provided corresponding to at least a predetermined finger portion of the plurality of finger portions, and a driving portion that drives a joint portion of the plurality of finger portions, and a predetermined portion closer to the distal end side than the joint portions. A contact detection unit that detects that a contact part has contacted the object,
   The predetermined contact portion of the predetermined finger portion of the hand mechanism moves toward the target position of the target object determined based on the position information of the target object acquired by the acquisition unit. The position of the predetermined contact portion is servo-controlled according to the predetermined servo control structure, and the predetermined contact portion contacts the object before the predetermined contact portion reaches the target position. When detected by the contact detector, the position servo loop including at least a position feedback system in the predetermined servo control structure is invalidated.
   Gripping system.
2. The predetermined servo control structure includes a position servo loop including a position feedback system, a speed servo loop including a speed feedback system, and a current servo loop including a current feedback system.
   When the contact detection unit detects contact of the predetermined contact portion with the object, the control device includes the position servo loop, the speed servo loop, and the current servo among the predetermined servo control structures. Disable all loops,
   The gripping system according to claim 1.
3. The predetermined servo control structure includes a position servo loop including a position feedback system, a speed servo loop including a speed feedback system, and a current servo loop including a current feedback system.
   The control device invalidates the position servo loop and the speed servo loop of the predetermined servo control structure when contact with the object at the predetermined contact portion is detected by the contact detection unit, The current servo loop remains activated;
   The gripping system according to claim 1.
4. The control device further derives a contact position that is a position of the predetermined contact portion when contact of the predetermined contact portion of the predetermined finger portion with the object is detected by the contact detection unit. And correcting the position information of the object acquired by the acquisition unit based on the contact position information regarding the contact position.
   The gripping system according to any one of claims 1 to 3.
5. The contact detection unit is provided corresponding to each of the plurality of finger parts of the hand mechanism, and a predetermined contact site on a distal end side from a joint part of each finger unit is detected by the contact detection unit. It is possible to detect contact with
   When the object is gripped by the hand mechanism, the control device has an interval between the predetermined contact portions in at least two gripping finger portions used for gripping the target object among the plurality of finger portions. Is expanded to a predetermined initial interval larger than the width between the predetermined gripping portions of the object, and the position of the predetermined contact portion is servo-controlled according to the predetermined servo control structure to control the hand mechanism. Approach the object,
   Furthermore, when the hand mechanism is approaching the object, the contact detection unit detects contact of the predetermined contact portion of either of the two gripping finger portions with the object. In this case, the control device moves the hand mechanism in the direction of the gripping finger part that is in contact with the target object, so that the target object is moved between the predetermined contact parts of the two gripping finger parts. Each predetermined gripping portion is positioned by setting the predetermined gripping portion to be in a state where each predetermined gripping portion of each of the two gripping finger portions is smaller than the predetermined initial interval. The gripping system according to claim 4, wherein a finger part is brought into contact with the predetermined gripping portion of the object and the object is gripped by the gripping finger part.
6. When gripping the object by the hand mechanism, the control device controls the arm mechanism and the hand mechanism based on the position information corrected based on the contact position information. The gripping system according to claim 5, wherein the gripping system is made to approach the object.
7. The contact detection unit is provided corresponding to each of the plurality of finger parts of the hand mechanism, and a predetermined contact site on a distal end side from a joint part of each finger unit is detected by the contact detection unit. It is possible to detect contact with
   When gripping the object by the hand mechanism, the control device servo-controls the drive unit of each gripping finger part used for gripping the object among the plurality of finger parts. Each gripping finger is controlled by servo-controlling the position of the predetermined contact portion according to the predetermined servo control structure until the corresponding contact detection unit detects contact of the predetermined contact portion with the object. A part close to the object,
   Furthermore, the control device sequentially operates the drive units of the gripping finger units when the contact detection unit corresponding to each operation detects the contact of the predetermined contact portion with the object. Once all the gripping finger portions have contacted the object, the drive unit of at least one gripping finger portion is actuated again to press the object with each gripping finger portion. The gripping system according to claim 4.
8. 8. When the object is gripped by the hand mechanism, the control device servo-controls the drive unit of each gripping finger based on the position information corrected based on the contact position information. The gripping system as described in.
9. After all the gripping finger portions have contacted the object, the control device again turns on the drive units of all the gripping finger portions in order to press the object with each gripping finger portion. 9. A gripping system according to claim 7 or 8 to be actuated.
10. Based on the contact position information related to the contact position of each gripping finger portion with the object, the current contact position of each gripping finger portion is an appropriate position for gripping the target object. And when it is determined that the current contact position of each gripping finger part is not an appropriate position for gripping the target object, the target object of at least one gripping finger part is moved to the target object. The gripping system according to any one of claims 7 to 9, wherein the object is pressed by each gripping finger portion after the contact position is changed.
    

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