JP5166151B2 - Robot finger and robot hand equipped with the same - Google Patents

Description

  The present invention relates to a robot finger for gripping a workpiece and a robot hand including the same.

  Conventionally, industrial robot hands having a plurality of fingers have been widely used for automation of workpiece conveyance (see, for example, Patent Documents 1 and 2). In order to prevent a finger from colliding with an external member such as a platform that supports a workpiece and damaging the robot hand, a contact member arranged so as to protrude from the fingertip, or the fingertip portion touched an external member. A sensor for detecting this is provided.

  FIG. 6 is a cross-sectional view showing a configuration of a conventional robot hand. A sensor 103 is provided on the finger body 102 of each robot finger 101 constituting the robot hand 100 shown in FIG. The sensor 103 includes a housing 104 built in the finger body 102 and a shaft 105 that can move forward and backward with respect to the housing 104. The shaft 105 is urged so as to protrude from the front end surface of the housing 104 by a coil spring 106 built in the housing 104. A contact portion 107 is fixed to the distal end portion of the shaft 105, and the contact portion 107 is disposed so as to protrude from the distal end of the finger body 102 together with a part of the shaft 105. A base end portion of the shaft 105 disposed in the housing 104 is formed in a bowl shape. The base end portion is always biased toward the inner surface of the housing 104 by the coil spring 106, and the conductor 108 is in contact with the inner surface of the housing 104. The base end portion of the shaft 105 is formed of a conductive material, and the base end portion of the shaft 105 and the conductor 108 are always in electrical conduction.

When gripping the workpiece 120 with the robot hand 100, first, the robot finger 101 is brought close to the table 121 that supports the workpiece 120. When the robot finger 101 gets too close to the table 121, the contact portion 107 first contacts the table 121. By this contact, the shaft 105 retreats into the housing 104 against the urging force of the coil spring 106. As a result, the conductor 108 is separated from the base end portion of the shaft 105, and the conduction with the base end portion of the shaft 105 is cut off. The input line 109 is electrically connected to the output line 110 through the conductor 108. As a result, a detection signal indicating the contact of the contact member 107 with the base 121 is output from the sensor 103 to the control device for the robot hand connected to the conductor 107. In response to the detection signal, the control device controls the operation of the robot hand 100 to avoid the finger body 102 from colliding with the table 121.
JP 60-39090 A JP-A-8-288356

  According to the above configuration, the finger main body 102 can be prevented from coming into contact with the base 121 and being damaged. However, since the contact portion 107 and the like protrude from the finger body 102 and the contact portion 107 is always interposed between the base 121 and the tip of the finger body 102, it is possible to grip a workpiece having a small height. It has become difficult. In particular, when the volume of the work 120 is smaller than the protruding length of the contact portion 107, it is necessary to incline the finger main body 102 with respect to the base 121, and there is a possibility that the holding operation is complicated.

  Therefore, an object of the present invention is to provide a robot finger and a robot hand that can easily grip a workpiece.

To achieve the above object, a robot finger according to the present invention comprises a finger body for gripping a workpiece and a contact member protruding from the tip of the finger body, and the finger body has a part of the tip. A protrusion that extends in the protrusion direction of the contact member, and further includes a detection device that detects contact with the outside of the contact member, the detection device including a housing built in the finger body, and the housing An advancing / retreating portion capable of advancing / retreating, a first urging member for urging the advancing / retreating portion in a direction to advance from the housing, and a detection portion configured to detect the contact when the advancing / retreating portion retreats into the housing And the housing is movably provided in the longitudinal direction of the finger body, the contact member is fixed to the tip of the advance / retreat portion and operates integrally with the advance / retreat portion, and the housing is attached to the finger body. The example Second biasing member is characterized by being provided for urging the leading end side.

According to such a configuration, the workpiece can be gripped using the protruding portion, and a thin workpiece can be easily gripped even if a contact member is provided. When an external force acts on the contact member at the time of contact with the outside, the advancing / retreating part moves against the urging force of the first urging member to detect this contact, and the housing against the urging force of the second urging member Can move. Thus, the external force acting on the contact member can be absorbed by the urging force of the second urging member, and the impact resistance of the detection device and the contact member can be enhanced.

  The protrusion may be provided along a part of the outer surface of the contact member. According to such a configuration, the rotation of the contact member with respect to the finger body can be restricted using the protrusion.

  The protruding length of the contact member with respect to the tip of the finger body is variable within a predetermined range, and the protruding length of the protruding portion with respect to the tip of the finger body is smaller than the minimum protruding length of the contact member. Good. According to such a configuration, even when the contact member moves to the minimum protrusion length due to contact with the outside or the like, the protrusion portion can be prevented from coming into contact with the external member and being damaged.

  The urging force that acts on the housing from the second urging member may be larger than the urging force that acts on the advance / retreat portion and the contact member from the first urging member. According to such a configuration, when the above external force is applied, first, the advancing / retreating part is moved against the urging force of the first urging member to detect contact with the outside of the contact member, and when the external force is excessive The housing is moved against the biasing force of the second biasing member. In this way, contact detection is performed based on a smaller urging force, and external force absorption is performed based on a larger urging force, thereby ensuring both contact detection accuracy and impact resistance.

  A robot hand according to the present invention is characterized by including at least one robot finger. According to this configuration, it is possible to provide a robot hand that can easily hold a workpiece in the same manner as described above.

  ADVANTAGE OF THE INVENTION According to this invention, in a robot finger provided with the contact member arrange | positioned so that it may protrude from the front-end | tip of a finger | toe main body, and a robot hand provided with this, a workpiece | work can be gripped easily.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a robot hand 1 according to the present invention. As shown in FIG. 1, the robot hand 1 includes a stay 2 for connecting to a robot arm 45, and a plurality of robot fingers 3 are attached to the stay 2. Each robot finger 3 is configured to be able to expand and contract the mutual distance between the fingertips, and the robot hand 1 holds the workpiece 40 (see FIG. 2) by changing the mutual distance between the fingertips as described later. be able to.

  The robot finger 3 is an articulated type and includes a plurality of finger bodies 4, 5 and 6. The proximal finger body 4 is swingably provided with respect to the stay 2, and the intermediate finger body 5 is swingably provided with respect to the proximal finger body 4. A joint member 7 is swingably connected to the middle finger body 5. The finger body 6 on the distal end side is fixed to a stay 8 formed integrally with the joint member 7 by a bolt 9 so that it can swing with respect to the intermediate finger body 5.

  The robot hand 1 includes a contact 10 that protrudes from the tip of the finger body 6 in order to prevent the finger body 6 on the tip side from being damaged.

  FIG. 2 is a cross-sectional view showing the tip portion of the robot finger 3. As shown in FIG. 2, the finger body 6 is formed in a rectangular cross section. A substantially cylindrical space 11 extending in the longitudinal direction is formed inside the finger body 6.

  The robot finger 3 is provided with a sensor 12 that detects that the contact 10 has come into contact with an external member such as a table that supports the workpiece. The sensor 12 includes a housing 13 built in the space 11 of the finger body 6, a shaft 14 that can be moved forward and backward with respect to the housing 13, and a spring 15 that biases the shaft 14.

  The housing 13 is formed in a substantially cylindrical shape, and a flange portion 16 extending outward in the radial direction is formed on the bottom wall 13a that forms the distal end surface. A stopper portion 17 extending radially inward is formed at the tip of the finger body 6. The flange portion 16 is supported by the stopper portion 17 to prevent the housing 13 from dropping out of the space 11 of the finger body 6.

  The shaft 14 is formed in a substantially cylindrical shape and penetrates the bottom wall 13 a that forms the distal end surface of the housing 13. The shaft 14 is guided by the through hole of the bottom wall 13a and is slidable in the axial direction of the housing 13 (that is, the longitudinal direction of the finger body 6). A base end portion of the shaft 14 is located in the internal space 18 of the housing 13, and a flange portion 19 that protrudes radially outward is integrally provided at the base end portion.

  Between the upper surface of the flange portion 19 and the upper wall 13b of the housing 13, a coil-shaped compression spring 15 that biases the shaft 14 is provided. The shaft 14 and the contact 10 are urged by the compression spring 15 in a direction to advance out of the housing 13. At this time, the lower surface of the flange portion 19 comes into contact with the upper surface of the bottom wall 13a of the housing 13, and the movement of the shaft 14 is restricted.

  A contact 10 is fixed to the tip of the shaft 14. For example, the contact 10 is fixed to the shaft 14 by press-fitting the tip of the shaft 14 into the hole 20 formed in the end face of the contact portion 10.

  For this reason, the contact 10 is arranged so as to protrude from the tip of the finger main body 6 together with a part of the shaft 14, and is movable within a predetermined range in the longitudinal direction of the finger main body 6. When the compression spring 15 is in the normal state as described above, the protrusion length of the contact 10 with respect to the finger body 6 is the largest. When the shaft 14 is retracted into the housing 13 from this state, the compression spring 15 is contracted and the protruding length of the contact 10 is reduced.

  The collar portion 19 is formed from a material having electrical conductivity, and a terminal 21 formed from the material having electrical conductivity is provided on the upper surface of the bottom wall 13 a of the housing 13. A wiring (not shown) is connected to the flange 19 and the terminal 21.

  When the compression spring 15 is in a normal state, the lower surface of the flange portion 19 is kept in contact with the terminal 21, and the flange portion 19 and the terminal 21 are electrically connected. When the shaft 14 and the contact 10 retreat into the internal space 18 of the housing 13 against the urging force of the compression spring 15, the flange portion 19 and the terminal 21 are physically separated, and the flange portion 19 and the terminal 21 are separated from each other. It will be in the state which is not electrically conducted. In this state, the sensor 12 outputs a detection signal indicating that a load that overcomes the urging force of the compression spring 15 acts on the contact 10 on a control device (not shown) of the robot hand 1 connected via a wiring (not shown). The Rukoto. The flange 19 and the terminal 21 that operate in this way constitute a detection unit that detects contact with the outside of the contact 10.

  More specifically, the space 11 in the finger body 6 has a stepped cylindrical shape whose diameter is larger on the distal end side than on the proximal end side. The outer diameter of the housing 13 is slightly smaller than the inner diameter of the proximal-side space on the smaller diameter side, and the housing 13 slides in the space 11 in the axial direction of the housing 13 (that is, the longitudinal direction of the finger body 6). It is possible.

  When the housing 13 is accommodated in the space 11, an annular gap 22 is formed in the housing 13 between the outer surface of the housing 13 and the inner surface of the finger body 6 on the distal end side having a large diameter. Become. A coiled compression spring 23 is accommodated in the gap 22. That is, the compression spring 23 is wound around the distal end portion of the outer peripheral surface of the housing 13. One end of the compression spring 23 is supported by a step 24 inside the finger body 6 formed between the space on the distal end side and the space on the proximal end side, and the other end is supported on the upper surface of the flange portion 16 of the housing 13. Has been. The housing 13 is urged by the compression spring 23 toward the distal end side in the longitudinal direction of the finger body 6, and the flange portion 16 is supported by the stopper portion 17 as described above, and the housing 13 is stationary.

  The spring constant of the compression spring 23 that biases the housing 13 is larger than the spring constant of the compression spring 15 that biases the shaft 14, and the biasing force that the housing 13 receives from the compression spring 23 is received from the compression spring 15 by the shaft 14. Greater than the force.

  FIG. 3 is a bottom view of the finger body 6 as viewed in the direction of arrow III in FIG. As shown in FIG. 3, the contact 10 has the same rectangular shape as the finger body 6 when viewed in the longitudinal direction of the finger body 6 (that is, the axial direction of the housing 13 and the shaft 14). A U-shaped protrusion 31 is integrally formed at the tip of the finger body 6. The protrusions 31 are provided along three of the outer peripheral surfaces of the contact 10. The U-shaped projecting portion 31 includes a first projecting portion 32, a second projecting portion 33, and a third projecting portion 34, and the outer surfaces of the projecting portions 32 to 34 are smooth on the outer surface of the finger body 6. It is continuous. In the present embodiment, the finger body 6 has a rectangular cross section, the outer surface thereof is defined by four planes, and the outer surfaces of the protrusions 32 to 34 are flush with the outer surface of the finger body 6. In addition, when the outer surface of the finger main body 6 forms a curved surface, it is preferable that the outer surface of the protrusion 31 is formed so as to be smoothly continuous with the curved surface.

  Thus, since the protrusion 31 is provided along the outer surface of the contact 10, even if a moment for rotating the contact 10 acts, the load is supported by the protrusion 31, and the rotation of the contact 10 is prevented. Can be regulated. By restricting the rotation of the contact 10 in this way, when the contact 10 is projected in the longitudinal direction of the finger body 6, the contact 10 is prevented from protruding outside the finger body 6 as indicated by a virtual line in FIG. 3. Can do. That is, it is possible to prevent the gripping operation of the work 40 (see FIG. 2) by the finger body 6 from being disturbed by the contact 10 protruding outward in this way.

  With reference to FIG. 2, a gripping operation of the workpiece 40 performed using the robot finger 3 will be described. First, the finger body 6 at the tip is brought close to the base 41 that supports the workpiece 40 by driving the robot finger 3. Next, the mutual distance between the finger bodies 6 is reduced, and the workpiece 40 is held by sandwiching the workpiece 40 between the finger bodies 6.

  Conventionally, when the height of the workpiece 40 is smaller than the protruding length of the contact 10, it is difficult to position the tip of the finger body 6 between the base 41 and the upper end surface of the workpiece 40. On the other hand, in the present embodiment, the protruding portion 31 protruding from the tip of the finger body 6 can be easily positioned between the base 41 and the upper end surface of the workpiece 40. 40 can be easily gripped. Thus, by providing the protrusion 31 on the finger body 6, the workpiece 40 can be easily grasped and the rotation of the contact 10 can be restricted.

  The protrusion 31 is preferably provided to achieve both of these effects, and the shape of the protrusion 31 is not limited to the above as long as these effects are achieved. For example, the protruding portion 31 of the above embodiment includes first to third protruding portions 32 to 34 that cover three of the outer peripheral surfaces of the contact portion 10, but at least one of the outer peripheral surfaces of the contact portion 10. It may be provided so as to follow.

  Note that when the cross-sectional shape of the shaft 14 and the cross-sectional shape of the hole 20 formed in the end face of the contact 10 are circular, the contact 10 is easily rotated with respect to the shaft 14. For this reason, in order to more reliably regulate the rotation of the contact 10, the cross-sectional shape of at least the tip portion of the shaft 14 and the cross-sectional shape of the hole 20 formed in the contact 10 may each be formed in a non-circular shape.

  Next, the operation of the robot hand when the contact 10 contacts an external member will be described with reference to FIG.

  As shown in FIG. 4A, when the finger body 6 at the tip is too close to the base 41 during the workpiece gripping operation, first, the contact 10 that protrudes from the tip of the finger body 6 in the longitudinal direction of the finger body is the base 10. 41 is contacted. Since the contact 10 is arranged in this manner, the finger body 6 can be prevented from immediately contacting an external member, but the contact 10 is based on the moving speed of the robot finger 3 immediately before the contact. The impact force F from the base 41 side acts.

  As shown in FIG. 4B, when this impact force F is received, first, the contact 10 moves together with the shaft 14 toward the longitudinal base end side of the finger body 6 against the urging force of the compression spring 15 having a small spring constant. Moving. As described above, this movement causes the flange portion 19 of the shaft 14 to move away from the terminal 21, and a detection signal indicating that the contact 10 contacts an external member is output to a control device (not shown).

  And the shaft 14 can move to a longitudinal direction base end side until the spring length of the compression spring 15 becomes the shortest as shown in FIG.4 (b). In this state, there is a predetermined clearance between the upper surface of the contact portion 10 and the lower surface 17 a of the stopper portion 17 of the finger body 6. In order to generate this clearance, the movable stroke of the shaft 14 is smaller than the distance between the lower surface 17a of the stopper portion 17 and the upper surface of the contact portion 10 in a steady state.

  When the impact force F is excessive, as shown in FIG. 4C, the compression spring 23 having a larger spring constant is contracted, and the contact 10 and the shaft 14 and the housing 13 are integrated. It moves in the space 11 of the main body 6 to the proximal end side in the longitudinal direction. Each of these components can move in the longitudinal direction until the upper surface of the contact 10 comes into contact with the lower surface 17a of the stopper portion 17 of the finger body 6.

  Thus, even if an excessive impact force F is generated when the contact 10 contacts an external member, the impact received by the contact 10 and the sensor 12 by the compression of the compression spring 23 can be absorbed. Can improve the impact resistance.

  Further, since the spring constant of the compression spring 23 is larger than the spring constant of the compression spring 15, the housing 13 does not move immediately after the collision, and only the shaft 14 and the contact 10 move. That is, the compression operation of the compression spring 23 is not related to the operation of detecting contact with the outside of the contact 10 and is performed only to absorb the impact force F. As described above, by appropriately setting the spring constants of the two springs 15 and 23, it is possible to achieve both the accuracy of detecting the contact and the impact resistance of the sensor 12 and the contact 10 at the same time.

  Next, a modified example of the above embodiment will be described based on FIG. In addition, about the structure same as the said embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 5, in the robot finger 53 of this example, a first space 61 extending in the longitudinal direction and a direction orthogonal to the longitudinal direction (hereinafter also simply referred to as “orthogonal direction”) are provided inside the finger body 56. A second space 62 extending to the first space 61 is formed, and the second space 62 communicates with a proximal end portion of the first space 61. The first space 61 is formed in a stepped cylindrical shape in which the diameter of the distal end is larger than the diameter of the proximal end.

  A substantially cylindrical shaft 63 is inserted into the first space 61. A flange 64 extending radially outward is integrally formed at an intermediate portion of the shaft 63, and when the flange 64 engages with the inner surface of the wall on the distal end side of the finger body 6, the shaft 63 is It prevents falling out of the space 61. The outer diameter of the shaft 63 is slightly smaller than the inner diameter of the first space 61 on the proximal end side, and the shaft 63 is guided by the inner surface of the first space 61 on the proximal end side and can slide in the longitudinal direction of the finger body 56. It has become. The contact 10 is fixed to the tip of the shaft 63 in the same manner as in the above embodiment.

  A gap 65 is formed between the outer surface of the shaft 63 and the inner surface on the distal end side of the first space 61. In the gap 65, a coil-shaped compression spring 66 provided so as to be wound around the distal end portion of the outer peripheral surface of the shaft 63 is accommodated.

  The housing 68 of the sensor 67 is fitted in the second space 62. The sensor 67 has a protrusion 69 protruding from one end surface of the housing 68. The protrusion 69 is provided so as to be able to advance and retreat with respect to the housing 68, and is always urged by the compression spring 70 in the direction of advancing from the housing 68, and the tip is located in the first space 61. The tip portion projects in the radially outer peripheral side, and is urged by the compression spring 70 to come into contact with the inner surface of the housing 68. This prevents the protrusion 69 from falling off the housing.

  The tip of the protrusion 69 is formed of a material having electrical conductivity, and a terminal 71 formed of a material having electrical conductivity is provided on the inner surface of the housing 68 that contacts the tip. ing. The tips of the protrusions 69 and the terminals 71 are connected to a robot hand control device (not shown) via wires (not shown).

  In a state in which the collar portion 64 is engaged with the inner surface of the finger main body 56, the proximal end portion of the shaft 63 is located on the distal end side with respect to the protrusion 69 protruding into the first space 61.

  In the robot finger 53 configured in this manner, when the contact 10 comes into contact with an external member and an impact force F directed toward the proximal end in the longitudinal direction of the finger body 56 acts on the contact 10, the contact 10 together with the shaft 63 compresses. It moves in the first space 61 toward the base end side in the longitudinal direction of the finger body 56 against the urging force of 66. In this movement process, the base end portion of the shaft 63 comes into contact with the protrusion 69 and tries to move further to the base end side. At this time, the protrusion 69 retracts into the housing 68 against the urging force of the compression spring 70 by the action of the wedge. As a result, the tip of the protrusion 69 is separated from the terminal 71, and a detection signal indicating that the contact 10 has come into contact with an external member is output from the sensor 67 to a control device (not shown) via a wiring (not shown).

  Thus, also in the present embodiment, the impact force acting on the contact 10 by the compression operation of the compression spring 66 can be absorbed, and the impact resistance of the sensor 67 and the contact 10 can be improved. Note that, by arranging the base end portion of the shaft 63 and the projecting portion 69 as close as possible, it is possible to ensure both detection accuracy and impact resistance.

  Further, the sensor 67 is accommodated in the second space 62 extending in the direction perpendicular to the longitudinal direction of the finger body 56, and a structure in which a spring is provided on the outer peripheral side of the sensor housing as in the first embodiment is avoided. . For this reason, it is possible to reduce the outer dimension of the finger body 56 particularly on the distal end side, and thus the contact 10 can also be reduced in size.

  Although the embodiment according to the present invention has been described so far, the scope of the present invention is not limited to the configuration exemplified in the above embodiment, and the above embodiment can be appropriately changed without departing from the present invention.

  The present invention is widely applicable to finger mechanisms of industrial robots.

It is a perspective view which shows the robot hand which concerns on embodiment of this invention. It is sectional drawing of the robot finger explaining the structure of the front-end | tip part of the robot finger of 1st Embodiment. It is the figure seen from the arrow III direction shown in FIG. It is a figure explaining operation | movement when a robot hand collides with the stand which supports a workpiece | work, (a) The state at the moment of collision, (b) The state which detected the contact, (c) The state which the housing retracted Respectively. It is sectional drawing of the finger mechanism explaining the structure of the front-end | tip part of the robot finger of the example of a change of embodiment of this invention. It is a figure explaining the structure of the conventional robot hand.

Explanation of symbols

1 Robot hand 3 Robot fingers 4, 5, 6 Finger body 10 Contact (contact member)
12 Sensor (detection device)
13 Housing 14 Shaft (advance / retreat)
15 Compression spring (first biasing member)
23 Compression spring (second biasing member)
53 Robot finger 56 Finger body 63 Shaft (moving member)
66 Compression spring (second biasing member)
67 Sensor (detection device)
68 Housing 69 Projection (advance / retreat)
70 Compression spring (first biasing member)

Claims (5)

A finger body for gripping the workpiece, and a contact member protruding from the tip of the finger body,
The finger body is provided with a protruding portion extending from a part of the tip thereof in the protruding direction of the contact member ,
A detection device for detecting contact with the outside of the contact member;
The detection device includes a housing built in the finger main body, an advancing / retreating portion that can be advanced / retracted with respect to the housing, a first urging member that urges the advancing / retreating portion in a direction to advance from the housing, A detection portion configured to detect the contact when the portion retreats into the housing;
The housing is provided so as to be movable in the longitudinal direction of the finger body, and the contact member is fixed to a distal end of the advance / retreat portion and operates integrally with the advance / retreat portion;
A robot finger , wherein the finger body is provided with a second urging member that urges the housing toward the distal end side of the finger body .   The robot finger according to claim 1, wherein the protruding portion is provided along a part of the outer surface of the contact member. The protruding length of the contact member relative to the tip of the finger body is variable within a predetermined range,
The robot finger according to claim 1 or 2, wherein a protruding length of the protruding portion with respect to a tip of the finger body is smaller than a minimum protruding length of the contact member. 2. The robot according to claim 1 , wherein an urging force acting on the housing from the second urging member is larger than an urging force acting on the advance / retreat portion and the contact member from the first urging member. Finger. A robot hand comprising at least one robot finger according to any one of claims 1 to 4 .

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