JP5787537B2 - Gripping device and robot device - Google Patents

Description

The present invention relates to a gripping device equipped with a piezoelectric vibration type pressure sensor in a gripping portion of a robot, and a robot device including the gripping device .

  In recent years, a robot hand as a gripping device has been required to have multiple functions so that it can grip an object to be gripped having various characteristics such as shape, hardness, surface property, and weight. Along with this, a sensor provided in the grip portion of the robot hand is required to have a sensitivity capable of obtaining a sense of pressure, a feeling of slip, and the like corresponding to a human fingertip. For this reason, the robot hand is required to control gripping an object to be gripped in the same manner as a human being by detecting a gripping state in real time with a pressure sensor provided in a gripping unit.

  As described above, strain gauges, capacitance type, conductive rubber, and the like have been developed as pressure sensors used in robot hands that are required to hold an object to be gripped with a sense similar to that of a human being.

  Conventionally, this type of pressure sensor is disclosed in Patent Documents 1 to 3.

  In the pressure sensor described in Patent Document 1, a plurality of pressure-sensitive rubbers arranged in a matrix are arranged on a flexible substrate attached to a grasping portion, and the sensor surface is protected and an object to be grasped is placed thereon. Because of the necessity of gripping flexibly, it has a structure in which each pressure-sensitive rubber is adhered and covered with a flexible layer.

  In addition, the pressure sensor described in Patent Document 2 has at least two electrode members in which electrodes are arranged in a regular arrangement on the surface or inside of a flexible and stretchable insulating film-like electrode member. An electrode part arranged in a bag shape is provided.

  The pressure sensor includes a substance replacement control unit that controls replacement of a substance to be placed in the bag-shaped electrode unit according to the type of material to be grasped. The pressure sensor includes an electrical output unit that outputs an electrical signal having a predetermined value to the electrodes of each electrode member, and an electrical measurement unit that measures an electrical signal generated between the electrodes of each electrode member. The substance replacement control means replaces the substance to be placed inside the bag of the bag-like electrode part. The electrical measuring means measures a change in the electrical signal generated between the electrodes of each electrode member supplied with the electrical signal of a predetermined value from the electrical output means, and the electrode member is based on the change in the electrical signal. The shape recognition information for recognizing the shape of the object to be gripped in contact with is obtained.

  Specifically, the pressure sensor 900 described in Patent Document 2 (FIG. 8) has a regular arrangement such as a matrix on the surface or inside of flexible and stretchable insulating films 901, 902 or the like. The electrodes 901a and 902a are provided. The films 901 and 902 are connected to electrical output means 903, and the electrical output means 903 is connected to electrical measurement means 904. The electrical measuring means 904 has a function of taking out an electrical signal between the electrodes of each film and detecting shape recognition information for recognizing the shape of the gripped member.

  The pressure sensor 900 (FIG. 9) is attached to the grip claws 911 and 911 of the robot hand 910 so that the shape of the object to be grasped can be easily measured only by grasping the member to be grasped.

  The pressure sensor of Patent Document 3 has a detection unit formed in a layered manner by alternately stacking a plurality of plate-like piezoelectric bodies and electrodes. The pressure sensor is connected to the detection unit by a processing circuit that processes the voltage induced in the opposing electrode, and the pressure sensor detects the pressure sensation by the induced voltage of the piezoelectric material that changes depending on the direction and magnitude of the force applied to the piezoelectric material. , Information about slipping and shear lines can be obtained.

JP 2006-136893 A Japanese Patent Laid-Open No. 2002-113585 Japanese Unexamined Patent Publication No. 60-034293

  However, when a robot hand holds a wide variety of objects to be grasped and moves or assembles the objects to be grasped, it is necessary to frequently repeat contact with the objects to be grasped. In particular, industrial robot hands have an enormous number of grips of objects to be gripped, and wear, scratches, dirt, deterioration, etc. of the sensor surface due to repeated gripping operations have occurred. In addition, industrial robot hands often use oil, organic solvents, and the like, and there is a problem that the sensor surface is more likely to be worn, scratched, soiled, deteriorated, and the like due to oil, organic solvents, and the like.

  The pressure sensor described in Patent Document 1 has a structure in which a flexible layer is closely attached to each pressure-sensitive rubber because of the need to protect the sensor surface and to flexibly grip an object to be gripped. There is a problem that it cannot be exchanged.

  The pressure sensor described in Patent Document 2 has a problem that since the film becomes a gripping surface, the entire pressure sensor must be replaced when the film is worn, damaged, or soiled.

  The pressure sensor described in Patent Document 3 is covered with a protective layer and a reinforcing layer. However, these two layers are integral with the sensor and cannot be replaced. For this reason, the pressure sensor described in Patent Document 3 has a problem that the entire pressure sensor must be replaced when the reinforcing layer is worn, damaged, or soiled.

  Thus, since the contact part of the pressure sensor which repeats a contact with a to-be-held object is integral with a pressure sensor, when it is necessary to exchange a contact surface, the pressure sensor of patent documents 1 thru / or 3 is contact surface. The entire pressure sensor had to be replaced.

  In particular, a versatile robot hand is equipped with two or more fingers, and all the pressure sensors attached to all the fingers must be replaced, requiring maintenance and time. There was a problem of high costs.

The present invention improves the maintainability and reduces the maintenance cost by replacing only the contact portion without replacing the entire pressure sensor when the contact portion that contacts the object to be grasped needs to be replaced. An object of the present invention is to provide a gripping device that achieves the above and a robot apparatus including the gripping device .

The gripping device of the present invention includes a piezoelectric vibration type pressure sensor formed by sandwiching a piezoelectric element having electrodes provided on both sides with a pair of circuit boards connected to the electrodes via the electrodes. The piezoelectric element, the electrode, and the pair of circuit boards are arranged in the gripping force direction of the gripping part at the gripping position of the gripping part that grips at the gripping position of the tip part and the intermediate part. Furthermore, a covering member made of an elastic member that covers the piezoelectric vibration type pressure sensor and the gripping position of the intermediate part in a U-shaped cross section and is detachably provided on the intermediate part, and the piezoelectric vibration type pressure sensor; A mounting member that attaches and detaches to the intermediate part, and attaches the tip part of the U-shaped section of the covering member in a state of covering the gripping position of the intermediate part to the intermediate part. It is said.
A robot apparatus according to the present invention includes a robot arm, the above-described gripping device provided in the robot arm, and a controller that controls operations of the robot arm and a gripping unit of the gripping device. It is said.

  The gripping device of the present invention can easily replace only the covering member in a timely manner even if the covering member is deteriorated, scratched, worn, or scraped due to repeated contact with the piezoelectric vibration type pressure sensor by gripping the object to be gripped. Can do.

  In addition, the gripping device of the present invention does not require the entire piezoelectric vibration type pressure sensor to be replaced, and only the covering member can be handled as a consumable part. Therefore, maintenance performance can be improved and maintenance cost can be reduced.

It is a schematic sectional drawing of the piezoelectric vibration type pressure sensor provided in the robot hand as a holding | grip apparatus of embodiment of this invention. It is sectional drawing of the holding part of the robot hand provided with the piezoelectric vibration type pressure sensor. It is EE arrow sectional drawing of FIG. 1 is a schematic overall view of an assembly robot. It is a top view of the robot hand of an assembly robot. It is an external appearance perspective view of a robot hand. It is a figure at the time of making the protective layer of the piezoelectric vibration type pressure sensor provided in a robot hand into two layers, and is a figure equivalent to FIG. It is a basic block diagram of the conventional shape recognition sensor. FIG. 10 is a perspective view of a contact-type shape sensing robot hand having a two-finger configuration in the prior art.

Hereinafter, a gripping device and an assembly robot as a robot device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a piezoelectric vibration type pressure sensor provided in a robot hand as a gripping device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a grip portion of a robot hand provided with a piezoelectric vibration type pressure sensor. FIG. 3 is a cross-sectional view taken along line EE in FIG. FIG. 4 is a schematic overall view of an assembly robot as the robot apparatus of the present invention . FIG. 5 is a plan view of the robot hand of the assembly robot. FIG. 6 is an external perspective view of the robot hand.

An assembly robot 100 (FIG. 4) as a robot apparatus is provided on the work table 3. The assembly robot 100 grips a workpiece W1 as an object to be gripped by a robot hand 2 as a gripping device provided at the tip of the robot arm 1 and incorporates it into another workpiece W2 on the work table 3. . Details of the assembly robot 100 will be described later.

  A piezoelectric vibration type pressure sensor (hereinafter simply referred to as “sensor”) 20 (FIG. 5) is formed by a known fixing method such as an adhesive on the fingertip portion 6a of the grip portion 6 of the robot hand 2 and the middle joint portion 6b. Is provided. The sensor 20 confirms the shape of the workpiece W1, detects the gripping force with which the robot hand 2 grips the workpiece W1, and allows the robot hand 2 to grip the workpiece W1 with the optimum gripping force.

  1 to 3, the sensor 20 includes a piezoelectric element 21, electrodes 22 a and 22 b disposed on both sides of the piezoelectric element 21, and flexible substrates 23 a and sandwiching the piezoelectric element 21 in contact with the electrodes 22 a and 22 b, respectively. 23b and the like. The flexible boards 23a and 23b as circuit boards are connected to one or more electrodes 22a and 22b corresponding to the piezoelectric element 21, and are integrated with the electrodes 22a and 22b by a known fixing method such as an adhesive. .

The sensor 20 is protected by a protective layer 24 (124) as a covering member. The protective layer 24 (124) has elasticity. Detection unit 7 for detecting the grip state of the workpiece by the sensor 20 the protective layer 24 and the (124) (FIG. 6) is formed.

  The protective part 24 of the sensor 20 (FIG. 2) provided in the fingertip part 6a as a gripping position on the side where the gripping part 6 that grips the work W1 of the robot hand 2 grips the work W1 and the middle joint part as the gripping position The protective layer 124 of the sensor 20 (FIG. 3) provided in 6b has a different shape.

  The sensor 20 (FIGS. 2 and 3) includes a piezoelectric element 21 and a pair of flexible substrates 23a and 23b arranged in the gripping force directions F1 to F4 (FIG. 5) of the gripping part 6, and a fingertip part 6a and a middle joint part. 6b.

  The protective layer 24 of the sensor 20 shown in FIG. 2 is mounted so as to wrap the sensor 20 and the fingertip portion 6a, and is formed in a bottomed cylindrical shape. The shape of the protective layer 24 may be cylindrical.

  The inner diameter of the protective layer 24 when not attached to the sensor 20 and the fingertip portion 6a is set smaller than the diameter formed by the sensor 20 and the fingertip portion 6a. For this reason, when the protective layer 24 is attached to the sensor 20 and the fingertip portion 6a, the protective layer 24 elastically contracts in the direction of the arrow B, covering the flexible substrate 23a on the side of the sensor 20 that grips the workpiece W1 and the fingertip portion 6a. And do not fall off the fingertip portion 6a.

  When the protective layer 24 is pulled in the direction of arrow F (FIG. 2), it can be removed from the sensor 20 and the fingertip portion 6a and replaced. For this reason, the protective layer 24 (FIG. 1) is separated from the flexible substrate 23a at the line AA and is detachable.

A protective layer 124 as a covering member of the sensor 20 shown in FIG. 3 is different in shape from the protective layer 24 shown in FIG. The protective layer 124 in FIG. 3 is a hook-shaped elastic member having a U-shaped cross section. The protective layer 124 covers the sensor 20 provided in the middle joint 6b of the grip 6 of the robot hand 2, and is fixed to the middle joint 6b by a pin 29 as a detachable attachment member . The protective layer 124 is elastically contracted in the direction of arrow D due to elasticity and is in close contact with the sensor 20. The protective layer 124 can be replaced by removing the pin 29.

  The protective layer 124 may have a single flat shape and may be elastically deformed when attached to the middle node 6b so as to cover the sensor 20 and be attached to the middle node 6b.

  Next, the configuration and operation of the assembly robot 100 will be described.

  The assembly robot 100 (FIGS. 4 to 6) includes a robot arm 1, a robot hand 2, a vision camera 4, and the like.

The robot arm 1 includes a vertical axis 31 erected on the work table 3, a rotation base 32 provided horizontally on the vertical axis 31, and a rotation base 32 that is rotatable up and down by a first horizontal axis 33. And a first arm 34 provided. Furthermore, the robot arm 1 is rotated at the tip of the first arm 34 by a second horizontal shaft 35 so as to be rotatable in the vertical direction, and the second arm 36 is rotated by the third horizontal shaft 37 in the vertical direction. The robot hand 2 is provided freely. The robot arm 1 includes a vision camera 4 provided on the robot hand 2 and a gripping unit 6.

  The grip 6 is composed of four fingers 38. The finger 38 includes a fingertip portion 6a and a middle joint portion 6b. The middle joint portion 6b is provided on the robot hand 2 so as to be horizontally rotatable by a joint J1. The fingertip portion 6a is provided on the middle joint portion 6b by the joint J2 so as to be horizontally rotatable.

  A sensor 20 that detects a gripping state when the gripping part 6 grips the work W1 is provided at a part of the fingertip part 6a and the middle joint part 6b that faces the work W1.

  The vision camera 4 recognizes the shapes and positions of the workpieces W1, W2 and the like placed on the work table 3. The information is sent to a controller (not shown). The controller (not shown) controls a drive device (not shown) that operates the vertical axis 31, the first horizontal axis 33, the second horizontal axis 35, the third horizontal axis 37, the joint J1 and the joint J2, and each axis and each Actuate the joints.

  As a result, the gripper 6 moves to a position where the workpiece W1 can be gripped by the operation of the robot arm 1 and the robot hand 2, and starts gripping the workpiece W1.

The gripping part 6 is provided with a detection part 7 (FIG. 6 ) for detecting the gripping state of the workpiece by the sensor 20 and the protective layer 24 (124). When the gripping unit 6 starts to grip the workpiece W1, the detection unit 7 detects the workpiece gripping state of the gripping unit 6 based on the deformation of the piezoelectric element 21, and sends the gripping state information to a controller (not shown) one by one.

  A controller (not shown) controls the torque of each joint J1, J2 of the gripping unit 6 based on the workpiece shape information from the vision camera 4 and the gripping state information from the detection unit 7, and gripping force ( F1 to F4) are adjusted. This adjustment is performed until the work W1 (FIG. 4) is completely assembled into the work W2.

  In the above description, the detection unit 7 is provided in the four-finger gripping unit 6, but is applied to a gripping unit having a plurality of fingers such as two fingers, three fingers, and five fingers.

As described above, the protective layer 24 shown in FIG. 2 and the protective layer 124 shown in FIG. 3 are members made of an elastic member such as rubber having oil resistance and chemical resistance such as butyl rubber and nitrile rubber.

  For this reason, the protective layer 24 shown in FIG. 2 can be easily removed and replaced by pulling in the direction of the arrow F, so that the entire sensor 20 does not need to be replaced and maintenance can be easily performed, and the maintenance cost can be reduced. Can do.

  Similarly, the protective layer 124 shown in FIG. 3 can be easily removed and replaced when the fixing pin 29 is pulled out, maintenance can be performed easily, and the entire sensor 20 does not need to be replaced, thereby reducing the maintenance cost. Can do.

  In addition, since the protective layers 24 and 124 are made of oil-resistant and chemical-resistant rubber, they can withstand long-term use even when the workpiece to which oil or chemicals are attached is gripped many times. Thus, the number of exchanges can be reduced.

  Further, the protective layer 24 (FIG. 2) that protects the sensor 20 provided on the fingertip portion 6a has a contracting force in the direction of the arrow B due to elasticity even when the gripping portion 6 is not gripping a workpiece. It acts in the direction which stabilizes contact with the electrode of a flexible substrate. As a result, contact resistance and chattering between the electrode of the piezoelectric element and the electrode of the flexible substrate can be suppressed.

  Similarly, the protective layer 124 (FIG. 3) that protects the sensor 20 provided in the middle joint portion 6b also has elasticity. For this reason, even when the gripping portion 6 is not gripping the workpiece, the protective layer 124 has a contraction force in the direction of arrow D in the direction that stabilizes the contact between the electrode of the piezoelectric element and the electrode of the flexible substrate. Acting on the node 6b, contact resistance and chattering can be suppressed.

  By the way, it is preferable that the protective layers 24 and 124 have excellent wear resistance in addition to oil resistance and chemical resistance. 7 has a two-layer structure in which the outer layers 224a and 324a and the inner layers 224b and 324b are integrated. The protective layer denoted by reference numeral 224 is used instead of the protective layer denoted by reference numeral 24 shown in FIG. The protective layer denoted by reference numeral 324 is used instead of the protective layer denoted by reference numeral 124 shown in FIG.

  In the case of rubber members having oil resistance and chemical resistance elasticity such as butyl rubber and nitrile rubber, the outer layer and the inner layer contain carbon black as a reinforcing material in order to improve the wear resistance of the outer layers 224a and 324a. It is. The blending ratio of carbon black is increased in an assembly process that particularly requires durability, and is decreased in an assembly process that is not necessary.

  The rigidity (e1) of the outer layers 224a and 324a and the rigidity (e2) of the inner layers 224b and 324b have a relationship of e1> e2, and the thickness (d1) of the outer layers 224a and 324a is the thickness of the inner layers 224b and 324b With respect to d2), d1 <d2. In this case, the thickness (d2) of the outer layer is set to a thickness that easily follows the rigidity of the inner layer so that the outer layer is difficult to separate from the inner layer.

  Therefore, the protective layer contains black carbon in the outer layer, and has the rigidity relationship (e1> e2) and the thickness relationship (d1 <d2). Accordingly, the protective layer can be elastically deformed easily following the surface property of the workpiece and the shape of the workpiece, so that the gripping performance of the gripping portion 6 is improved. Moreover, since the wear resistance of the protective layer is improved and the protective layer can be used for a long period of time, the number of maintenance of the grip portion 6 can be reduced.

  Also, the carbon black can reduce the electrical resistance per unit volume of the outer layer, and even if the gripping part 6 grips an electrical component that easily causes electrostatic breakdown such as an IC component or an electronic component, Can be prevented, and electrostatic breakdown of electrical components can be prevented. In addition, the sensor 20 provided in the grip portion 6 can be electrically protected.

  Furthermore, when carbon black is contained in the outer layer, the surfaces of the protective layers 224 and 324 become black, and the light reflectance is reduced. For this reason, the boundary between the workpiece and the protective layer detected by the vision camera 4 becomes clear, and the shape of the workpiece is easily detected.

  Note that the protective layer may include a large amount of carbon black in a portion close to the outside and a portion close to the inside without being divided into an outer layer and an inner layer. Even in this case, it is possible to improve the wear resistance of the protective layer, prevent electrostatic breakdown of electrical components, and accurately detect the shape of the workpiece by the vision camera 4.

1: robot arm, 2: robot hand (gripping device), 4: vision camera, 6: gripping part,
6a: fingertip part (gripping position), 6b: middle joint part (gripping position), 20: piezoelectric vibration type pressure sensor, 21: piezoelectric element, 22a, 22b: electrode, 23a, 23b: flexible board (circuit board), 24 , 124, 224, 324: protective layer (covering member), 29: pin (attachment member), 224a, 324a: outer layer, 224b, 324b: inner layer, 100: assembly robot (robot device) , F1 to F4: robot hand Gripping force direction, W1, W2: Workpiece (object to be grasped), J1, J2: Joint .

Claims (8)

A piezoelectric vibration type pressure sensor formed by sandwiching a piezoelectric element provided with electrodes on both sides with a pair of circuit boards connected to the electrodes via the electrodes , and an object to be grasped between a tip portion and an intermediate portion. A gripping device comprising the piezoelectric element, the electrode, and the pair of circuit boards arranged in a gripping force direction of the gripping part at a gripping position of the intermediate part of a gripping part gripped at a gripping position,
A covering member made of an elastic member that covers the piezoelectric vibration type pressure sensor and the gripping position of the intermediate portion in a U-shaped cross section and is detachably provided on the intermediate portion;
A mounting member detachably attached to the intermediate portion, which attaches a U-shaped tip portion of the covering member in a state of covering the piezoelectric vibration type pressure sensor and the gripping position of the intermediate portion to the intermediate portion; With
A gripping device characterized by that. The covering member is formed of a rubber member, and the portion close to the outside contains carbon black.
The gripping device according to claim 1. The covering member is formed of a rubber member, is formed of an outer layer and an inner layer, and contains carbon black in the outer layer,
The outer layer of the covering member is more elastic and thinner than the inner layer,
The gripping device according to claim 1. The elastic member is made of butyl rubber or nitrile rubber,
Gripping device according to claim 1, characterized in that. A robot arm,
The gripping device according to any one of claims 1 to 4, provided on the robot arm;
A controller for controlling the operation of the robot arm and the gripping part of the gripping device;
A robot apparatus characterized by that. The controller controls the operation of the robot arm and the gripping unit of the gripping device according to the gripping force detected by the piezoelectric vibration type pressure sensor included in the gripping device.
The robot apparatus according to claim 5. The gripping device includes a vision camera.
The robot apparatus according to claim 5 or 6, characterized in that: The controller controls the operation of the robot arm and the gripping unit of the gripping device according to information detected by the vision camera;
The robot apparatus according to claim 7.

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