JP2013107147A - Collision detection device of workpiece conveyor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a collision detection device of a workpiece conveyor capable of surely detecting a collision of a hand 16 with an obstacle.SOLUTION: The collision detection device for detecting the collision of a workpiece conveyor includes a hand 16 disposed above a workpiece 22 to fix the workpiece 22, and a drive arm 12 provided with a tip shaft directed in a vertical direction connected the hand 16 and moving the hand 16. The collision detection device includes pressure sensors s1 to s4 for detecting pressure generated between the tip and the hand, and determines the collision of the workpiece conveyor with an obstacle based on detection results of the pressure sensors. When the collision with the obstacle is detected, the workpiece conveyor 11 is forcibly stopped, and a warming signal is outputted.

Description

  The present invention relates to a collision detection apparatus that detects that a workpiece transfer machine used when transferring a workpiece from a workpiece holder to a desired processing position has collided with an obstacle.

  For example, in a processing apparatus such as a laser processing machine, a plurality of workpieces to be processed are placed on a work holder, and if necessary, the placed workpiece is moved to a desired processing position of the processing apparatus. Carry and process.

  At this time, the workpiece is automatically conveyed from the workpiece holder to the machining position using a workpiece conveyance machine (see, for example, Patent Document 1). The workpiece transfer machine includes a plurality of vacuum pads, a hand that fixes the workpiece by setting the air pressure in each vacuum pad to a negative pressure, and a drive arm that can move the hands in any direction. Then, the workpiece is sucked and fixed to the hand using the vacuum pad, and in this state, the drive arm is operated to convey the workpiece placed on the workpiece holder to a desired machining position.

  Since such a workpiece conveyance machine automatically conveys the workpiece to a desired processing position, there is a possibility of colliding with an obstacle in the middle of conveyance, and it is desired to somehow prevent this.

Japanese Patent Laid-Open No. 11-5632

  As described above, in the conventional work transfer machine, the hand may collide with an obstacle during movement, and the occurrence of the collision is surely detected and the occurrence of the collision is notified, or the apparatus is forcibly stopped. It was hoped that.

  The present invention has been made in order to solve such a conventional problem. The object of the present invention is to make a collision of a work transporter capable of reliably detecting that a hand has collided with an obstacle. It is to provide a detection device.

  In order to achieve the above object, the invention described in claim 1 of the present application has a hand that is disposed above the work and fixes the work, and a tip shaft that is connected to the hand in a vertical direction, In a collision detection device for detecting a collision with an obstacle of a work transfer machine provided with a drive arm for moving a hand, a plurality of installations are provided at a connecting portion between the tip shaft and the hand, and the tip portion A pressure detecting means for detecting a pressure generated between the hand, a collision determining means for judging that the work transporter has collided with an obstacle based on the pressure detected by the pressure detecting means, and the collision And an output means for outputting a collision detection signal when a collision with an obstacle is detected by the determination means.

  The invention described in claim 2 is characterized in that the hand has a vacuum pad for sucking and fixing the work with negative pressure air.

  According to a third aspect of the present invention, the pressure detecting means has an element (for example, a piezoelectric element) that outputs a voltage signal corresponding to the magnitude of the applied pressure, or a resistance value corresponding to the magnitude of the applied pressure. It is one of elements that change (for example, a strain gauge).

  According to a fourth aspect of the present invention, the collision determination means obtains the maximum value Pmax and the minimum value Pmin of the pressure values detected by the plurality of pressure detection means, and the difference value (Pmax−Pmin) is preset. When the difference reference value is exceeded, it is determined that the vehicle has collided with an obstacle present in the lateral direction with respect to the hand.

  According to a fifth aspect of the present invention, in the collision determination unit, when the pressure value detected by at least one of the plurality of pressure detection units exceeds a preset pressure reference value, the hand It is determined that the vehicle collides with an obstacle existing below.

  According to the first aspect of the present invention, a plurality of pressure detection means are provided at the connecting portion between the tip shaft of the drive arm and the hand, and the hand collides with an obstacle based on the pressure detected by each pressure detection means. Therefore, it is possible to detect with high accuracy that the hand has collided with the obstacle.

  According to the second aspect of the present invention, since the vacuum pad is mounted on the hand and the work is sucked and fixed, the work can be reliably conveyed. Furthermore, when it collides with an obstacle, this can be detected immediately and the drive arm can be stopped.

  In the invention of claim 3, since an element that generates a voltage corresponding to the pressure or an element whose resistance value changes according to the pressure is used as the pressure detection means, the pressure generated between the tip shaft and the connecting portion is highly accurate. Therefore, it is possible to improve the accuracy of collision detection.

  In the invention of claim 4, when the difference value (Pmax−Pmin) between the maximum value Pmax and the minimum value Pmin of the pressure values detected by the plurality of pressure detecting means exceeds a predetermined value, the hand exists in the lateral direction. Since it is determined that the vehicle has collided with the obstacle, the collision direction of the obstacle can be notified, and the accuracy of collision detection can be improved.

  In the invention of claim 5, when the pressure value detected by at least one of the plurality of pressure detecting means exceeds the pressure reference value, it is determined that the hand has collided with an obstacle present in the downward direction. Therefore, the collision direction of the obstacle can be notified, and the accuracy of collision detection can be improved.

It is a block diagram of the collision detection apparatus which concerns on one Embodiment of this invention, and a workpiece conveyance machine. It is explanatory drawing which shows the detailed structure of the connection part of a drive arm and a hand of the collision detection apparatus which concerns on one Embodiment of this invention. It is a perspective view which shows the structure of the hand of the workpiece conveyance machine by which the collision detection apparatus which concerns on one Embodiment of this invention is mounted. It is a flowchart which shows the processing operation of the collision detection apparatus which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram schematically showing a configuration of a work transfer machine on which a collision detection apparatus according to an embodiment of the present invention is mounted, and FIG. 2 shows details of a connecting portion between a drive arm 12 and a hand 16. It is explanatory drawing which shows a simple structure. As shown in FIG. 1, the workpiece transfer machine 11 includes a drive arm 12 and a hand 16 attached to the distal end portion of the drive arm 12.

  The drive arm 12 includes three joint portions 13a, 13b, and 13c that can rotate, and the joint portions 13a to 13c are connected by a plurality of shafts 14. Further, the tip of the drive arm 12 is a tip shaft 14 a that faces in the vertical direction, and the tip shaft 14 a is connected to the hand 16 by a connecting portion 20.

  The hand 16 has a plurality of vacuum pads 21, and the work 22 placed on the work holder 23 is sucked and fixed by making the air pressure in the vacuum pad 21 negative. Lift 22 upward. Then, the workpiece 22 is conveyed to a processing position of a processing machine (not shown) such as a laser processing machine. The detailed configuration of the hand 16 will be described later.

  The work transfer machine 11 is connected to the robot controller 15, and the joint portions 13 a to 13 c are operated by the control of the robot controller 15. That is, the joint portions 13a to 13c are operated by the control signal output from the robot controller 15, and the hand 16 connected to the distal end shaft 14a of the drive arm 12 is moved in the three axial directions of up and down, left and right, and front and rear. Can do.

  The robot controller 15 is electrically connected to the pressure calculation unit 17 and stops the workpiece transfer machine 11 when the pressure calculation unit 17 detects that the hand 16 has collided with an obstacle as will be described later. To control.

  Further, as shown in FIGS. 2A and 2B, the connecting portion 20 includes four support columns 42 provided on the distal end shaft 14 a, and each support column 42 is connected to the hand 16 via the connection plate 41. It is connected. Moreover, as shown in FIG.2 (b), each of the four support | pillars 42 is each provided with pressure sensors (pressure detection means) s1-s4. The pressure sensors s <b> 1 to s <b> 4 are, for example, piezoelectric elements, and generate a voltage corresponding to the pressure generated in each column 42. The generated voltage is amplified by the amplifier 18 shown in FIG. In addition, it is also possible to use the strain gauge from which resistance value changes according to pressure instead of a piezoelectric element as pressure sensors s1-s4.

  As will be described later, the pressure calculation unit 17 performs a process of determining whether or not the hand 16 collides with an obstacle based on each voltage detected by each pressure sensor s1 to s4. The pressure calculation unit 17 is electrically connected to the alarm device 19 and outputs an alarm signal to the alarm device 19 when a collision of the hand 16 is detected. When the pressure calculation unit 17 detects that a collision has occurred in the hand 16, the alarm device 19 notifies that the collision has occurred by lighting a lamp, sound, or the like. That is, the pressure calculation unit 17 has a function as a collision determination unit that determines that the workpiece transfer machine 11 has collided with an obstacle based on the pressure detected by the pressure detection unit (pressure sensors s1 to s4). ing. Furthermore, when the collision determination means detects a collision with an obstacle, it has a function as an output means for outputting a collision detection signal.

  Note that the pressure calculation unit 17 illustrated in FIG. 1 can be configured as an integrated computer including a central processing unit (CPU) and storage means such as a RAM, a ROM, and a hard disk.

  Next, a detailed configuration of the hand 16 will be described. FIG. 3 is a perspective view showing a detailed configuration of the hand 16. As shown in FIG. 3, the hand 16 includes a base portion 31, and a plurality (six in this example) of vacuum pads 21 facing the base portion 31 in the vertical direction are provided. Further, an air pipe (not shown) is connected to the vacuum pad 21, and the air pressure of the air pipe is made negative while keeping each vacuum pad 21 in contact with the surface of the work 22. 1), one of the workpieces 22 stacked on top of each other is sucked and fixed. Then, the work 22 can be moved to a desired processing position by moving the hand 16 in the three-axis directions by the drive arm 12.

  The hand 16 includes a rod 32 and a proximity switch (upper proximity switch) 33 installed in the vicinity of the upper tip 32 a of the rod 32, and the hand 16 descends toward the work 22, When the tip 32 b comes into contact with the workpiece 22, the rod 32 is pushed upward, and the upper tip 32 a of the rod 32 approaches the proximity switch 33. Therefore, based on the detection signal of the proximity switch 33, it can be detected that the hand 16 is pressing the work 22 with a constant force, and consequently the work 22 is detected by the vacuum pad 21 as being sucked and fixed. can do.

  Further, a proximity switch (lower proximity switch) 34 is provided at the lower end 32 b of the rod 32, and the proximity switch 34 determines whether or not the workpiece 22 exists in the workpiece holder 23. That is, when the work 22 is detected by the proximity switch 34, a process of sucking and transporting the work 22 by the vacuum pad 21 is executed, and when the work 22 is not detected by the proximity switch 34, the work holder 23. In this case, it is determined that the workpiece 22 does not exist, and the conveyance process is stopped.

  A connecting member 35 is provided at a substantially central portion of the hand 16, and the connecting member 35 is connected to the connecting plate 41 shown in FIG. Accordingly, since the hand 16 is connected to the drive arm 12 via the connection plate 41, one piece of the work 22 placed on the work holder 23 is controlled by controlling the drive arm 12 under the control of the robot controller 15. It can be taken out one by one and transported to a desired lowered position.

  Next, a specific operation of the collision detection process by the pressure calculation unit 17 will be described with reference to a flowchart shown in FIG. First, in step S11, the pressure calculation unit 17 determines whether or not detection signals from the pressure sensors s1 to s4 are generated. If it is determined that no detection signal is generated (NO in step S11), the detection signal wait state is entered.

  When it is determined that a detection signal is generated (YES in step S11), in step S12, the pressure calculation unit 17 determines that at least one of the pressures detected by the pressure sensors s1 to s4 is at least one. It is determined whether or not it is larger than a preset pressure reference value A.

  If it is determined that the detected pressure is greater than the pressure reference value A (YES in step S12), it is determined that an obstacle existing in the vertical direction of the hand 16 has collided with the hand 16. In step S <b> 16, the pressure calculation unit 17 outputs an emergency stop signal to the robot controller 15 illustrated in FIG. 1 and outputs an alarm signal to the alarm device 19. As a result, the work transfer machine 11 is forcibly stopped. Furthermore, a warning by sound or light is issued to notify the operator that a collision has occurred.

  On the other hand, when the pressure detected by an arbitrary pressure sensor (here, s1) is smaller than the pressure reference value A (NO in step S12), in step S13, the pressure calculation unit 17 includes the other three units. The pressures detected by the pressure sensors s2 to s4 are acquired.

  Next, in step S14, the pressure calculation unit 17 obtains the maximum value Pmax and the minimum value Pmin of the pressure detected by the four pressure sensors s1 to s4, and further calculates the difference value (Pmax−Pmin). .

  In step S15, the pressure calculation unit 17 determines whether or not the difference value (Pmax−Pmin) calculated in the process of step S14 is larger than a preset difference reference value B. If the difference value (Pmax−Pmin) is smaller than the difference reference value B (NO in step S15), the pressure is generated in at least one pressure sensor, but the magnitude is small, so a collision occurs. It is determined that it has not been performed, and the process returns to step S11.

  On the other hand, if the difference value (Pmax−Pmin) is larger than the difference reference value B (YES in step S15), a large difference has occurred in the pressure detected by each of the pressure sensors s1 to s4. It is determined that a strong force was applied in the lateral direction. That is, it is determined that the vehicle has collided with an obstacle present in the lateral direction of the hand 16. Then, the process proceeds to step S16.

  In step S <b> 16, the pressure calculation unit 17 outputs an emergency stop signal to the robot controller 15 as described above, outputs an alarm signal to the alarm device 19, forcibly stops the workpiece transfer machine 11, and A collision detection signal is output to the alarm device 19. At this time, if YES in the process of step S12, it is determined that the vehicle has collided with an obstacle existing below the hand 16, and this is output to the alarm device 19, and YES in the process of step S15. When it becomes, it judges that it collided with the obstacle which exists in the horizontal direction with respect to the hand 16, and outputs this to the alarm device 19. That is, when a pressure greater than the pressure reference value A is detected by any of the pressure sensors s1 to s4, it is determined that the vehicle has collided with an obstacle existing below the hand 16. Furthermore, when the difference between the maximum value Pmax and the minimum value Pmin among the pressures detected by the pressure sensors s1 to s4 is larger than the difference reference value B, the pressure is smaller than the pressure reference value A. Therefore, it is determined that the hand 16 has collided with an obstacle present in the lateral direction. Thus, it is possible to detect that the hand 16 has collided with an obstacle present in the vertical direction or the horizontal direction based on the magnitude of the pressure detected by each of the pressure sensors s1 to s4.

  In this way, in the collision detection device for a workpiece transfer machine according to the present embodiment, a plurality (four in this example) of pressure sensors s1 to s4 are installed in the connecting portion 20 that connects the driving arm 12 and the hand 16. Based on the magnitude of the pressure detected by each of the pressure sensors s1 to s4, it is detected whether or not the hand 16 of the workpiece transfer machine 11 has collided with an obstacle. Therefore, it is possible to detect the collision with the obstacle with high accuracy, stop the driving arm 12 and notify the operator, and the work transfer machine 11 may collide with the obstacle and be damaged. It becomes possible to prevent damage to the object itself.

  Further, as the pressure sensors s1 to s4, an element that generates a voltage according to pressure (for example, a piezoelectric element) or an element whose resistance value changes according to pressure (for example, a strain gauge) is used. The pressure generated between the two parts can be detected with high accuracy, and the accuracy of collision detection can be improved.

  Furthermore, when the difference value (Pmax−Pmin) between the maximum value Pmax and the minimum value Pmin of the pressure values detected by the plurality of pressure detection means exceeds a predetermined value, the hand 16 becomes an obstacle present in the lateral direction. Since it is determined that the vehicle has collided, the collision direction of the obstacle can be notified, and the accuracy of collision detection can be improved.

  As mentioned above, although the collision detection apparatus of the conveyance machine of this invention was demonstrated based on embodiment of illustration, this invention is not limited to this, The structure of each part is the thing of arbitrary structures which have the same function Can be replaced.

  The present invention can be used to detect that a hand provided in a transporter has collided with an obstacle.

DESCRIPTION OF SYMBOLS 11 Work conveying machine 12 Drive arm 13a, 13b, 13c Joint part 14 Axis 14a Tip axis 15 Robot controller 16 Hand 17 Pressure calculation part 18 Amplifier 19 Alarm device 20 Connection part 21 Vacuum pad 22 Work 23 Work holder 31 Base part 32 Rod 32a Upper part Tip 32b Lower tip 33 Proximity switch (Upper proximity switch)
34 Proximity switch (lower proximity switch)
35 connecting member 41 connecting plate 42 support column s1 to s4 pressure sensor

Claims (5)

A hand that is arranged above the workpiece and fixes the workpiece;
In a collision detection device for detecting a collision with an obstacle of a work transfer machine having a tip axis that is connected to the hand in a vertical direction, and a drive arm that moves the hand,
A plurality of connecting portions between the tip shaft and the hand, and pressure detecting means for detecting pressure generated between the tip portion and the hand;
Collision determination means for determining that the workpiece transfer machine has collided with an obstacle based on the pressure detected by the pressure detection means;
An output means for outputting a collision detection signal when a collision with an obstacle is detected by the collision determination means;
A collision detection device for a work transfer machine, comprising:   The collision detection apparatus for a workpiece transfer machine according to claim 1, wherein the hand has a vacuum pad for sucking and fixing the workpiece with negative pressure air.   The pressure detection means is either an element that outputs a voltage signal corresponding to the magnitude of an applied pressure, or an element whose resistance value changes according to the magnitude of the applied pressure. The collision detection apparatus of the workpiece conveyance machine in any one of Claim 1 or Claim 2.   The collision determination means obtains a maximum value Pmax and a minimum value Pmin of the pressure values detected by the plurality of pressure detection means, and when the difference value (Pmax−Pmin) exceeds a preset difference reference value. The collision detection device for a workpiece transfer machine according to any one of claims 1 to 3, wherein the collision detection device determines that the vehicle has collided with an obstacle present in a lateral direction with respect to the hand.   The collision determination unit is configured such that when the pressure value detected by at least one of the plurality of pressure detection units exceeds a preset pressure reference value, the hand has collided with an obstacle existing below. It is judged that it is a thing, The collision detection apparatus of the workpiece conveyance machine of any one of Claims 1-4 characterized by the above-mentioned.

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