JP2015100884A - Robot hand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot hand for positioning an object by engaging with a hand body, and capable of restraining the occurrence of excessive restriction, when gripped by a plurality of fingers for synchronously operating for opening-closing.SOLUTION: The robot hand comprises a hand body 51, a plurality of fingers 50 movably supported by the hand body 51, synchronously openable-closable and capable of gripping a jig 10 by opening-closing operation, a positioning plate 56 provided in the band body 51 and capable of positioning the jig 10 when the jig 10 contacts with the hand body 51, a jig gripping part 53 movably provided on at least two fingers 50 among the plurality of fingers 50 and capable of gripping the jig 10 so as to maintain contact with the hand body 51 of the jig 10 in response to the opening-closing operation of the plurality of fingers 50 and an elastic member 54 for elastically supporting the jig gripping part 53 to at least respective two fingers 50.

Description

  The present invention relates to a robot hand including a plurality of fingers capable of gripping an object such as a workpiece.

  Conventionally, a robot arm having a plurality of frames connected to each other by joints has been developed, and various end effectors connected to the most distal side frame of the robot arm have been developed. As one type of end effector, a robot hand (hereinafter referred to as a hand) having a plurality of fingers capable of gripping an object such as a workpiece is widely used.

  As this hand, a technique is provided in which a hole is provided in the palm of the hand body, a protrusion of an object such as a tool is engaged in the hole, and the object is gripped by four independently movable fingers. (Patent Document 1). In this hand, the object can be centered and positioned with respect to the hand body by engaging the protrusion of the object with the hole of the hand body. According to this hand, the object is positioned by the projection and the hole, and after the positioning, each finger moves independently and grips the object, so that a large gripping force is exhibited without causing excessive restraint. can do.

  On the other hand, a technique has been known in which a hand has three fingers that can be opened and closed synchronously, and a chuck portion having a tapered surface is formed on each finger (Patent Document 2). In this hand, the taper portion formed on the target object such as a work is gripped by the chuck portion of each finger, thereby preventing the gripped target object from falling off. Further, according to this hand, since the chuck portion grips the tapered portion, the finger can be centered and positioned simply by gripping the object.

JP 2012-16754 A JP 2005-111598 A

  However, the hand described in Patent Document 1 cannot be centered using the hole when the object is a workpiece or the like that does not have a protrusion. For this reason, although it is necessary to center by four fingers, since these fingers can move independently, it was difficult to position a work with high accuracy by a single hand.

  On the other hand, in the hand described in Patent Document 2, since the object is gripped only with a finger, gripping force becomes insufficient when gripping a tool or jig larger than a workpiece or the like assumed as the object. It was difficult to perform accurate work.

  In order to solve these problems, a hand is conceivable in which a hole is provided in the palm of the hand body and a chuck is provided on a plurality of fingers that can be opened and closed synchronously. In this case, the object is provided with a protrusion that can be engaged with the hole and a taper that can be engaged with the chuck. However, in such a hand, the object is centered and positioned with respect to the hand main body by the hole and the protrusion, but in addition, the core is also moved by a plurality of fingers synchronously closing. To be positioned. For this reason, there is a possibility that the object is over-constrained when the positioning by the hole and the protrusion and the positioning by the finger are shifted. When such over-constraint occurs, there is a problem that the accuracy of centering in gripping the target object is lowered, and as a result, the precision of work by the target object may be decreased.

  An object of the present invention is to provide a robot hand that is positioned by engaging an object with a hand body and that can suppress the occurrence of over-restraint when it is gripped by a plurality of fingers that open and close synchronously. Objective.

  A robot hand according to the present invention is provided on the hand body, a plurality of fingers that are supported so as to be movable with respect to the hand body, can be opened / closed synchronously, and can grasp an object by an opening / closing operation. And a positioning unit capable of positioning the object when the object comes into contact with the hand main body and at least two fingers of the plurality of fingers, and the plurality of fingers. In response to the opening / closing operation, the gripping portion is elastically moved with respect to each of the gripping portion capable of gripping the target object and each of the at least two fingers so as to maintain contact of the target object with the hand body. And an elastic support part to support.

  According to the present invention, the positioning unit positions the object with respect to the hand body, and the elastic support unit elastically supports the holding unit when the plurality of finger holding units hold the object. . For this reason, when the positioning by the positioning part and the positioning by the gripping part are shifted, the elastic support part is deformed, and the positioning position by the gripping part is corrected to the positioning position by the positioning part. Can be suppressed.

It is explanatory drawing which shows schematic structure of the robot apparatus which concerns on embodiment of this invention. 1 is a perspective view showing a schematic configuration of a robot hand according to an embodiment of the present invention. It is a side view showing a schematic structure of a jig grasped by a robot hand concerning an embodiment of the invention. It is sectional drawing which shows schematic structure of the robot hand which concerns on embodiment of this invention. It is the schematic which shows the operation | movement which a robot hand hold | grips a jig | tool, (a) is the state which one finger contacted the jig | tool, (b) is the state which two fingers contacted the jig | tool, (c) is Three fingers are in contact with the jig, and (d) is a state in which the three fingers are holding the jig. It is sectional drawing which shows schematic structure of the other form of the elastic support part in the robot hand which concerns on embodiment of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the robot apparatus 1 includes a robot main body 2 that is an articulated robot and a control device 3 that controls the operation of the robot main body 2.

  The robot body 2 includes a 6-axis articulated arm (hereinafter referred to as an arm) 4 as a robot arm and a hand (robot hand) 5 as an end effector. In the present embodiment, a 6-axis articulated arm is applied as the arm 4, but the number of axes may be changed as appropriate according to the application and purpose as long as a plurality of axes are provided.

  The arm 4 includes a plurality of first frames 61 to sixth frames 66 that are connected to each other by joints, a base portion 67 that is supported by connecting the proximal end sides of the first frames 61, and first shafts 71 to 61 that are joints. 6 shafts 76. Each of the frames 61 to 66 has a fixed length. However, for example, a frame that can be expanded and contracted by a linear actuator may be adopted. In the present embodiment, all joints are rotary joints, but the present invention is not limited to this, and some joints may be linear motion joints. The base 67 is an installation part of the arm 4 and is fixed to the upper surface of a gantry (not shown).

  Each of the first shaft 71 to the sixth shaft 76 includes a motor and a speed reducer (not shown), a joint mechanism, an encoder that detects a rotation angle of the motor, a current sensor that detects a current supplied to each motor, A torque sensor that detects the torque of the shafts 71 to 76 is provided. Each motor, encoder, current sensor, and torque sensor are all connected to the control device 3.

  The hand 5 is connected to and supported by the sixth frame 66 on the most distal end side of the arm 4, and at least one degree of freedom in position and posture is adjusted by the operation of the arm 4. The hand 5 includes three fingers 50 and a hand main body 51 that supports the interval between the fingers 50 so that the fingers 50 can be opened and closed. The hand 5 can hold an object such as a workpiece or the jig 10 by a closing operation. It has become. In the present embodiment, the hand 5 can grip the object by the closing operation, but is not limited to this. For example, the hand 5 can grip the object by either the opening / closing operation or the opening operation. Also good.

  The control device 3 is configured by a computer and controls the robot body 2. The computer constituting the control device 3 includes, for example, a CPU, a RAM that temporarily stores data, a ROM that stores a program for controlling each unit, and an input / output interface circuit. The control device 3 moves the position and orientation of the arm 4 by supplying required power required for the operation of the motor from a power supply main body (not shown) to the motor.

  Next, the configuration of the hand 5 and the jig 10 will be described in detail with reference to FIGS. In the present embodiment, the longitudinal direction parallel to the rotation center line of the hand 5 is defined as the axial direction, and the direction orthogonal to the rotation center line is defined as the radial direction.

  Each finger 50 of the hand 5 includes a bracket 52, a jig gripping part (grip part) 53, an elastic member (elastic support part) 54, and a work gripping part 55. The finger 50 is supported by a motor (not shown) so as to be movable with respect to the hand main body 51, can be opened and closed in synchronization, and can hold the jig 10 or a workpiece by a closing operation.

  The bracket 52 is substantially L-shaped, and has one end portion movably supported by the hand body 51 and the other end portion provided toward the distal end side in the axial direction of the hand 5. Each bracket 52 is moved in the radial direction in synchronization with the hand main body 51, and the finger 50 is opened and closed by this movement.

  The jig gripping portion 53 is provided with an inclined surface 53a that is inclined 45 ° by expanding the diameter of the hand main body 51 with respect to the axial direction, and is supported by the mounting bolt 80 so as to be movable in the radial direction with respect to the bracket 52. ing. The jig holding portion 53 can press the jig 10 against the hand main body 51 in accordance with the closing operation of the plurality of fingers 50, and can hold the jig 10 so as to maintain the contact of the jig 10 with the hand main body 51. It has become.

  The inclined surface 53a is preferably formed of a smooth surface such as metal or plastic without providing an elastic body such as rubber or a high friction material. Thereby, the inclined surface 53a can easily slide with respect to the inclined surface 12a of the jig 10, and the jig 10 can be pulled into the hand body 51 side.

  The elastic member 54 is made of a rubber flat plate, and is interposed between the bracket 52 and the jig gripping portion 53, and elastically supports the jig gripping portion 53 with respect to the bracket 52. . As the rubber material here, a material capable of elastic deformation more than the displacement between the positioning position by the positioning plate 56 and the positioning position by the gripping of the three fingers 50 when the jig 10 is gripped is selected. . As the rubber material, a material that is not plastically deformed even when a gripping force by each finger 50 and a force that is 1/3 of the weight of the jig 10 acts is selected.

  A mounting bolt 80 passes through the elastic member 54, and the elastic member 54 is sandwiched between the bracket 52 and the jig gripping portion 53 with an appropriate tightening force by the mounting bolt 80. The mounting bolt 80 is bonded and fixed to the jig gripping portion 53 by a screw lock or the like.

  The workpiece gripping portion 55 has, for example, a stepped portion 55 a at the tip, and is fixed to the bracket 52 by a mounting bolt 81. In the present embodiment, the step portion 55a is provided only at one place, but the present invention is not limited to this, and the step portion 55a has a plurality of step portions and inclined portions to grip a plurality of types of workpieces having different outer diameters. May be. In order to prevent the workpiece from dropping, the workpiece gripping portion 55 may be provided with a protrusion or a high friction portion.

  Further, by sandwiching a shim between the bracket 52 and the workpiece gripping portion 55, when the workpiece is gripped by the three fingers 50, the center of the workpiece and the hand 5 may be aligned. . Since the three fingers 50 open and close in synchronization, once centering is performed, the position reproducibility of the center of the workpiece can always be maintained when the workpiece is gripped again.

  The hand main body 51 of the hand 5 is provided with a positioning plate 56 as a positioning portion at the tip end in the axial direction, and the positioning plate 56 is configured so that the jig 10 is in contact with the hand main body 51. Can be positioned. The positioning plate 56 is plate-shaped, and the front end surface is the abutting surface 56a. A center hole (hole) 57 as an engaging portion formed on the center line, and an engaging portion formed at the peripheral portion. A peripheral hole (hole) 58 is provided. Each finger 50 is movable in the radial direction around the positioning plate 56. That is, the abutting surface 56a is positioned along the opening / closing direction of the finger 50 and the jig 10 is abutted against it.

  The jig 10 is an assembly jig capable of performing a plurality of assembly steps on the workpiece. However, the jig 10 is not limited to this, and other types of jigs may be used. As shown in FIG. 3, the jig 10 has a substantially cylindrical shape, and includes a jig body 11, a flange-shaped gripped portion 12 formed at one end, and the gripped portion 12 and the jig body 11. An inclined surface 12a that connects the peripheral surfaces with an inclination of 45 ° and a contact surface 13 that is an end surface on the gripped portion 12 side are provided. Further, the contact surface 13 is provided with a center pin 14 disposed in the center and projecting in the axial direction, and a peripheral pin 15 disposed in the vicinity of the peripheral edge portion and projecting in the axial direction.

  Here, the center pin 14 and the peripheral pin 15 of the jig 10 can be simultaneously fitted into the central hole 57 and the peripheral hole 58 of the hand main body 51, respectively. Ten centering and circumferential phase alignment can be realized. Moreover, the contact surface 13 of the jig 10 and the abutting surface 56a of the hand main body 51 are brought into contact with each other by this fitting, and the axial position of the jig 10 with respect to the hand main body 51 by this contact. The combination can be realized.

  The operation of the hand 5 described above will be described below with reference to FIGS.

  When the hand 5 grips a workpiece, the workpiece gripping portion 55 of each finger 50 is used. For this reason, the control device 3 operates the arm 4 to move the hand 5 to the workpiece mounting table so as to face the workpiece, and the inner surface of the workpiece gripping portion 55 of each finger 50 or the stepped portion 55a around the workpiece. To be placed. The control device 3 closes each finger 50 and grips the workpiece by the inner surface of the workpiece gripping portion 55 or the stepped portion 55a. After gripping the workpiece, the arm 4 is moved and moved to an appropriate position such as assembling the workpiece to another workpiece, and after the position of the workpiece is determined, each finger 50 of the hand 5 is opened to release the workpiece, Move on to the next operation.

  When the hand 5 holds the jig 10, the jig holding portion 53 of each finger 50 is used. For this reason, as shown in FIG. 4, the control device 3 operates the arm 4 to move the hand 5 to the mounting table of the jig 10 so as to face the jig 10, and the center of the abutting surface 56 a of the hand 5. The center pin 14 and the peripheral pin 15 of the jig 10 are fitted into the hole 57 and the peripheral hole 58. At this time, the gripping force of the finger 50 of the hand 5 is not utilized, and the center pin 14 and the peripheral pin 15 are fitted into the central hole 57 and the peripheral hole 58 by controlling the force of the arm 4, so And phase alignment in the rotation direction can be realized with high accuracy.

  After the center pin 14 and the peripheral pin 15 are fitted in the central hole 57 and the peripheral hole 58, the control device 3 moves each finger 50 to the center side in synchronization by a closing operation. As a result, the inclined surface 53a of the jig holding portion 53 and the inclined surface 12a of the jig 10 come into contact with each other, and each finger 50 biases the jig holding portion 53 toward the center of rotation by a closing operation. The tool 10 is pressed to the hand body 51 side. By this pressing, the contact surface 13 of the jig 10 and the abutting surface 56a of the hand main body 51 are in close contact with each other, and the axial alignment of the jig 10 with respect to the hand main body 51 can be realized by this close contact.

  When the jig 10 is gripped by the three fingers 50, the jig 10 is positioned at the center position by fitting the center pin 14 and the center hole 57. On the other hand, the center position determined by the closing operation of each finger 50 may not match the center position determined by the fitting of the center pin 14 and the center hole 57 due to an assembly error or the like. In this case, any elastic member 54 of the three fingers 50 after gripping the jig 10 is pressed and deformed so that the center pin 14 and the center hole 57 are not excessively constrained. I have to.

  That is, as shown in FIG. 5, after the center pin 14 and the peripheral pin 15 are fitted into the central hole 57 and the peripheral hole 58, the fingers 50a, 50b, and 50c are synchronized and moved to the center side by a closing operation. (The white arrow in the figure). Then, as shown in FIG. 5A, the jig gripping portion 53 of the finger 50 a first comes into contact with the jig 10, and the other fingers 50 b and 50 c are not in contact with the jig 10.

  As shown in FIG. 5 (b), the control device 3 controls the hand 5 by force control, and it is assumed that the gripping force does not reach the target value when only the finger 50a comes into contact, and the fingers 50a, 50b, The closing operation of 50c is continued. Thereby, the elastic member 54 of the finger 50a is pressed by the gripping force of the hand 5, and is elastically deformed into a crushed shape. Further, the jig gripping portion 53 of the finger 50 b comes into contact with the jig 10, and the other fingers 50 c are not in contact with the jig 10.

  And as shown in FIG.5 (c), the control apparatus 3 continues performing the closing operation | movement of each finger | toe 50a, 50b, 50c. As a result, the elastic member 54 of the finger 50a is further pressed by the gripping force of the hand 5, and the elastic member 54 of the finger 50b is pressed by the gripping force of the hand 5 and elastically deforms into a crushed shape. Further, the jig gripping portion 53 of the finger 50c comes into contact with the jig 10.

  Thereafter, as shown in FIG. 5 (d), the control device 3 causes the fingers 50a, 50b, 50c to close, elastically deforms the elastic members 54, 54, 54 of the fingers 50a, 50b, 50c, and The closing operation is stopped after the gripping force acting on 50a reaches the target value in the force control. After the closing operation is stopped, the jig holding portions 53, 53, 53 of the fingers 50a, 50b, 50c all come into contact with the jig 10, and each jig holding portion 53 receives a repulsive force from the elastic member 54. The jig 10 is pressed. As a result, as shown in FIG. 4, the inclined surface 53a of each jig gripping portion 53 presses the inclined surface 12a of the jig 10, and the jig 10 is pressed against the abutting surface 56a. Sticking and tilting can be prevented. In addition, although the case where each finger | toe 50a, 50b, 50c contacts sequentially was demonstrated here, the order of contact is not restricted to this, Other orders may be sufficient and it is made for two or more fingers 50 to contact simultaneously. Also good.

  As described above, according to the robot apparatus 1 of the present embodiment, the positioning plate 56 positions the jig 10 with respect to the hand main body 51, and the elastic member 54 elastically supports the jig holding portion 53. Yes. Therefore, when the positioning by the positioning plate 56 and the positioning by the jig gripping portion 53 are deviated, the elastic member 54 is deformed, and the positioning position by the jig gripping portion 53 is corrected to the positioning position by the positioning plate 56. . Thereby, generation | occurrence | production of the over restraint by two types of positioning can be suppressed.

  Moreover, according to the robot apparatus 1 of the present embodiment, since the workpiece gripping portion 55 having the stepped portion 55a is provided, it is possible to grip workpieces having various shapes. In this case, there is no need to use the jig gripping portion 53, and since the elastic member 54 is not interposed in the workpiece gripping portion 55, the workpiece can be centered with high accuracy, and the workpiece gripping and healing can be performed. The tool 10 can be gripped with high accuracy.

  In the above-described embodiment, the case where the elastic support portion is configured by the elastic member 54 which is a member different from the jig gripping portion 53 has been described. However, the present invention is not limited to this, and the jig gripping portion 53 is attached to the bracket 52. Other configurations may be used as long as they can be elastically supported. For example, as shown in FIG. 6, the elastic support portion may be configured by a leaf spring 154 formed integrally with the jig gripping portion 53. In this case, the end of the leaf spring 154 is fixed to the bracket 52 by adhesion or the like. However, the fixing means between the leaf spring 154 and the bracket 52 is not limited to adhesion, and for example, appropriate fixing means such as screwing can be employed. By integrally forming the leaf spring 154 and the jig gripping portion 53, the number of parts can be reduced.

  In the above-described embodiment, the case where the elastic member 54 is interposed between the bracket 52 and the jig gripping portion 53 has been described. However, the present invention is not limited to this. For example, the elastic member 54 may be interposed between the work gripping portion 55 and the jig gripping portion 53. Also in this case, the jig gripping portion 53 is indirectly elastically supported by the bracket 52.

  Further, in the above-described embodiment, the case where the positioning portion is configured by the abutting surface 56a and the center hole 57 and the peripheral hole 58 that are the engaging portions has been described, but the present invention is not limited thereto, and the jig 10 is Other configurations may be used as long as they can be positioned. For example, when it is not necessary to set the circumferential phase, the peripheral hole 58 may not be provided. Further, the engaging portion is not limited to the engagement between the pins 14 and 15 and the holes 57 and 58, and may be an engaging portion that can be engaged with the jig 10 such as an appropriate uneven shape. Furthermore, the abutting surface 56a may not be provided as long as it can be positioned in the axial direction by the engaging portion.

  In the above-described embodiment, the case where the inclined surface 53a of the jig gripping portion 53 is formed to be inclined by 45 ° has been described. However, the present invention is not limited to this. For example, it can be set as appropriate according to the weight and gripping force of the jig 10 within a range of about 30 ° to 60 °.

  Moreover, although embodiment mentioned above demonstrated the case where the inclined surfaces 53a and 12a were provided in both the jig | tool holding part 53 and the jig | tool 10, it is not restricted to this. For example, if only one has an inclined surface, the jig 10 can be pressed against the hand body 51.

  Further, in the above-described embodiment, the case where the jig gripping portion 53 grips the jig 10 has been described. However, the present invention is not limited to this, and a workpiece may be gripped.

  In the above-described embodiment, the case where a vertical articulated 6-axis articulated robot arm is applied as the arm 4 has been described, but the present invention is not limited thereto. For example, the present invention can also be applied to robots other than 5-axis, 7-axis, horizontal articulated robots, orthogonal robots, and articulated robots.

(Example)
The jig 10 was gripped using the hand 5 described above. Here, the hand 5 has a gripping force of 14 N, and the jig 10 has a weight of 1 kg. Further, the positional deviation between the positioning position by the three fingers 50 of the hand 5 and the positioning position by the positioning plate 56 is 0.1 mm, the size of the elastic member 54 is 13.8 mm in length, 10 mm in width, and 5 mm in thickness. In this case, the static shear coefficient of the rubber needs to be 0.9 MPa or less. Therefore, natural rubber with a hardness of 50 having a static shear coefficient of 0.7 MPa was selected as the elastic member 54.

  The jig 10 was held by the hand 5. First, a gripping force of 14N was applied to the elastic member 54 of the finger 50a that contacts the jig 10, and this elastic member 54 was elastically deformed by 0.139 mm. Here, since the displacement of each positioning position is 0.1 mm, the amount of deformation of the elastic member 54 of the finger 50c that finally comes into contact with the jig 10 is 0.039 mm, and the gripping force of this elastic member 54 is 3. 9N. The gripping force of the elastic member 54 of the second finger 50b is the gripping force (3.9 to 14N) between the first elastic member 54 and the last elastic member 54.

  When the hand 5 grips and lifts the jig 10 having a weight of 1 kg from the mounting table, the force in the gravity direction acting on each finger 50 is 3.3 N. Since the force in the opening direction of the finger 50 is 1.56 N, it was confirmed that the finger 50 can be gripped without being spread by the weight of the jig 10.

DESCRIPTION OF SYMBOLS 1 ... Robot apparatus, 5 ... Hand (robot hand), 10 ... Jig (object), 50, 50a, 50b, 50c ... Finger (plural fingers), 51 ... Hand main body, 53 ... Jig grip part (gripping) Part), 53a ... inclined surface, 54 ... elastic member (elastic support part), 56 ... positioning plate (positioning part), 56a ... abutting surface, 57 ... center hole (engagement part, hole), 58 ... peripheral hole ( (Engagement part, hole), 61-66 ... plural frames, 71-76 ... shaft (joint), 154 ... leaf spring (elastic support part)

Claims (7)

The hand body,
A plurality of fingers that are movably supported with respect to the hand body, can be opened and closed synchronously, and can grip an object by an opening and closing operation;
A positioning portion that is provided in the hand body and is capable of positioning the object when the object comes into contact with the hand body;
The object is provided so as to be movable on at least two fingers of the plurality of fingers, and the object can be gripped so as to maintain contact of the object with the hand body in accordance with the opening / closing operation of the plurality of fingers. Gripping part,
An elastic support portion that elastically supports the grip portion with respect to each of the at least two fingers.
Robot hand characterized by that. The grip portion includes an inclined surface capable of pressing the object toward the hand body by opening and closing the plurality of fingers.
The robot hand according to claim 1. The elastic support portion is an elastic member interposed between each of the at least two fingers and the grip portion.
The robot hand according to claim 1 or 2, wherein The elastic support portion is integrally formed with the grip portion.
The robot hand according to claim 1 or 2, wherein The positioning part is
Abutting surface along the opening / closing direction of the plurality of fingers and capable of being positioned by being abutted against the object,
An engaging portion engageable with the object so as to position the object abutted against the abutting surface in a direction along the abutting surface;
The robot hand according to any one of claims 1 to 4, wherein: The engaging portion is a pin protruding from the abutting surface toward the object, or a hole formed in the abutting surface.
The robot hand according to claim 5, wherein: A plurality of frames connected to each other by joints, and the robot hand described in any one of claims 1 to 6 connected to the most distal frame of the plurality of frames.
A robot apparatus characterized by that.

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