JP2020075353A - Robot system - Google Patents

Abstract

To provide a robot system in which the wrist is operated within a range not causing damages to a filament body, and thereby stabilizing life of the filament body, and reducing frequency of maintenance.SOLUTION: In a robot system 1 comprising a robot body 2 and a control device 3, the robot body 2 includes three wrist elements 26, 27, 28 at the end of an arm 24. A wired filament body 5 is connected from a filament body exit disposed in the first wrist element to an end effector 4 fixed to the third wrist element, via an aerial path outside of the robot body. The control device is provided with: an angle calculation part which calculates an angle around a coordinate axis using a position where minimal load is applied to the filament body as a reference, of a straight line projecting straight lines LA and LB that connect the filament body exit to a specific point of the filament body on a plane surface which is orthogonal to the coordinate axis, in an orthogonal coordinate system having one coordinate axis extending in a direction along a first axis L4 using the filament body exit as an origin O; and a determination part which determines whether an absolute value of the angle calculated by the angle calculation part exceeds a predetermined angle threshold or not.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a robot system.

  Conventionally, a part of the filamentous body that has been wired via the inside of the robot is taken out to the outside of the wrist and connected to a tool attached to the tip of the wrist, so that it is provided in the external space of the wrist. An industrial robot is known that has a sufficient extra length to absorb bending and twisting of the linear body associated with the movement of the wrist and reduce damage to the linear body (see, for example, Patent Document 1). ).

JP, 2003-305683, A

However, even in the industrial robot of Patent Document 1, depending on the operating angle of the wrist, excessive twisting occurs in the striatum, considerable damage is applied to the striatum without noticing, and the life is shortened early. There is an inconvenience that it ends up.
An object of the present invention is to provide a robot system capable of operating a wrist within a range that does not damage the striatum, stabilizing the life of the striatum, and reducing maintenance frequency. ..

  One aspect of the present invention includes a robot main body and a controller that controls the robot main body, and the robot main body is supported at the tip of an arm so as to be rotatable around a first axis along the longitudinal axis of the arm. A first wrist element, a second wrist element rotatably supported by the first wrist element about a second axis intersecting the first axis, the second wrist element, and the second axis. A third wrist element rotatably supported about a intersecting third axis, and a linear body wired through the inside of the arm, the linear body outlet provided in the first wrist element. From the robot body to an end effector fixed to the third wrist element via an aerial path outside the robot body, and the control device moves in a direction along the first axis with the linear body outlet as an origin. In a Cartesian coordinate system having one extending coordinate axis, a straight line connecting the linear body outlet and a specific point of the linear body is projected on a plane orthogonal to the coordinate axis, and the load applied to the linear body is the most. An angle calculation unit that calculates an angle around the coordinate axis based on a small position, and a determination unit that determines whether or not the absolute value of the angle calculated by the angle calculation unit exceeds a predetermined angle threshold value. It is a robot system.

  According to this aspect, the filament body that has been wired via the inside of the arm from the filament body outlet of the first wrist element attached to the tip of the arm of the robot body passes through the aerial path outside the robot body. And is connected to an end effector fixed to the third wrist element. In this case, if the second wrist element is rotated about the second axis with respect to the first wrist element, or the third wrist element is rotated about the third axis with respect to the second wrist element, the aerial path changes. Then, the amount of twist at a specific point of the striatum changes according to the magnitude of the rotation angle.

  According to this aspect, the angle calculation unit calculates the angle around the coordinate axis with reference to the position where the load of the straight line projecting the straight line connecting the specific point and the linear body exit onto the plane orthogonal to the coordinate axis is the reference, The determination unit determines whether or not the calculated absolute value of the angle exceeds the angle threshold. It is considered that the calculated angle represents the amount of twist of the linear body at the position of the specific point, and when the angle is larger than the angle threshold value, the linear body is greatly damaged by the twist. By changing the operation program and control based on the judgment result, it is possible to operate the wrist within the range that does not damage the striatum, stabilize the life of the striatum, and maintain it. The frequency can be reduced.

In the above aspect, the control device includes a distance calculation unit that calculates a distance between the linear body outlet and a specific point of the linear body, and the determination unit, the distance calculated by the distance calculation unit. However, it may be determined whether or not a predetermined distance threshold corresponding to the angle is exceeded.
With this configuration, when the second wrist element is rotated about the second axis with respect to the first wrist element or the third wrist element is rotated about the third axis with respect to the second wrist element, the aerial path is changed. As a result, the amount of tension or the amount of compression at a specific point of the linear body changes depending on the size of the rotation angle.

  The distance calculation unit calculates the distance of the straight line connecting the specific point and the striatum exit, and the determination unit determines whether or not the calculated distance exceeds the distance threshold corresponding to the angle. The calculated distance is considered to be representative of the amount of tension or compression of the striatum at the position of the specific point.If this distance is greater than the distance threshold, the striatum is significantly damaged by twisting. Given. By changing the operation program and control based on the judgment result, it is possible to operate the wrist within the range that does not damage the striatum, stabilize the life of the striatum, and maintain it. The frequency can be reduced.

Further, in the above aspect, the control device may control the robot body within an angle range in which the angle does not exceed the angle threshold.
With this configuration, the robot main body can be continuously operated at the angle of each wrist element that causes less damage to the linear body, the life of the linear body can be stabilized, and the maintenance frequency can be reduced.

Further, in the above aspect, when it is determined that the angle exceeds the angle threshold, the control device may include a notification unit that notifies that effect.
With this configuration, it is possible to notify the operator that the damage to the striatum is large, and to prompt the operator to correct the operation program.

Further, in the above aspect, the control device may control the robot body within a distance range in which the distance does not exceed the distance threshold.
With this configuration, the robot main body can be continuously operated at the angle of each wrist element that causes less damage to the linear body, the life of the linear body can be stabilized, and the maintenance frequency can be reduced.

Further, in the above aspect, the control device may include a notification unit that notifies that when the distance is determined to exceed the distance threshold.
With this configuration, it is possible to notify the operator that the damage to the striatum is large, and to prompt the operator to correct the operation program.

Further, in the above aspect, the control device may store the angles sequentially calculated by the angle calculation unit, and calculate the life of the filamentous body based on the stored time-series angles. ..
With this configuration, it is possible to make the damage to the filamentous body more concrete by the calculated life, and it is possible to prompt the correction of the operation program based on the life.

  According to the present invention, it is possible to operate the wrist within a range that does not damage the filament, stabilize the life of the filament, and reduce the maintenance frequency.

It is the whole block diagram which shows the robot system which relates to one execution form of this invention. It is a block diagram explaining the control apparatus of the robot system of FIG. FIG. 3 is a diagram illustrating how the determination unit of the control device in FIG. 2 determines the amount of damage at a specific point A. FIG. 4 is a diagram illustrating how the determination unit of the control device in FIG. 3 is a flowchart illustrating an operation of the robot system of FIG. 6 is a flowchart illustrating a life calculation routine of the flowchart in FIG. 5.

A robot system 1 according to an embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the robot system 1 according to the present embodiment includes a robot body 2 and a control device 3 that controls the robot body 2.

  The robot body 2 is, for example, a 6-axis articulated robot, and includes a base 21 installed on the floor surface F, and a swivel barrel 22 rotatably supported with respect to the base 21 about a vertical first axis L1. , A first arm 23 rotatably supported by the swivel barrel 22 about a horizontal second axis L2, and a second arm 23 rotatably supported by the first arm 23 about a horizontal third axis L3. An arm (arm) 24 and a triaxial wrist unit 25 attached to the tip of the second arm 24 are provided.

  The triaxial wrist unit 25 includes a first wrist element 26 rotatably supported with respect to the second arm 24 about a fourth axis (first axis) L4 extending in a direction along the longitudinal axis of the second arm 24, A second wrist element 27 rotatably supported with respect to the first wrist element 26 about a fifth axis (second axis) L5 orthogonal to the fourth axis L4, and a fourth axis L4 orthogonal to the fifth axis L5. And a third wrist element 28 rotatably supported with respect to the second wrist element 27 about a sixth axis (third axis) L6 passing through the intersection of the fifth axis L5.

  The second arm 24 and the first wrist element 26 have a hollow structure including a hollow hole 26a that extends along the fourth axis L4 around the fourth axis L4. The second wrist element 27 and the third wrist element 28 also have a hollow structure including hollow holes 27a and 28a that extend along the sixth axis L6 around the sixth axis L6.

  The laser processing tool (end effector) 4 is fixed to the third wrist element 28, for example. A high-rigidity cable (not shown) for driving the laser processing tool 4 and the like penetrates the second arm 24 and the hollow hole 26a of the first wrist element 26 from the rear of the second arm 24, and then the first wrist element. From the outlet of the hollow hole 26a of 26 (stripe body outlet), through the hollow path, through the hollow holes 27a and 28a of the second wrist element 27 and the third wrist element 28, it is connected to the laser processing tool 4. .. By wiring the highly rigid cable along the fourth axis L4 and the sixth axis L6, excessive twist or bending due to the rotation of the first wrist element 26, the second wrist element 27, and the third wrist element 28 is applied to the cable. No need to add.

  On the other hand, the low-rigidity optical fiber cable (filament) 5 that has been guided through the hollow hole 26a to the outlet of the hollow hole 26a of the first wrist element 26 together with the cable and the like is an aerial path different from the high-rigidity cable. Is connected to the laser processing tool 4 via. Since the optical fiber cable 5 is not wired along the fourth axis L4 and the sixth axis L6, the optical fiber cable 5 absorbs twists and bends caused by rotation of the first wrist element 26, the second wrist element 27, and the third wrist element 28. Wiring is performed with sufficient extra length.

However, at the specific point A arranged at the connecting portion 41 of the optical fiber cable 5 to the laser processing tool 4 or the specific point B arranged at an intermediate position in the length direction of the optical fiber cable 5, each wrist element 26, Depending on the postures of 27 and 28, excessive bending, pulling or compression may act. The specific points A and B can be set arbitrarily.
The control device 3 includes a processor and a memory, and as shown in FIG. 1, an origin O is an exit center of the hollow hole 26a of the first wrist element 26, and an X axis (coordinate axis) extending in a direction along the fourth axis L4. Defines an exit coordinate system that is an orthogonal coordinate system that includes

  Then, the control device 3 calculates the coordinates of the specific points A and B based on the angle information of the wrist elements 26, 27 and 28 of the robot body 2. The coordinates of the connection portion 41 of the laser processing tool 4 can be uniquely calculated based on the angle information of the wrist elements 26, 27, 28 and the dimensions of the laser processing tool 4, and the coordinates of the intermediate position of the optical fiber cable 5. Can be estimated based on the angle information of each wrist element 26, 27, 28.

Controller 3, as shown in FIG. 2, the calculated specific point A, straight line LA connecting the coordinates and the origin O of B, LB assumed, the straight line LA, the length of the LB (distance) A _R , B _R, and an angle calculation unit 32 that calculates angles A _θ and B _θ with _respect to the Z axis when the straight lines LA and LB are projected onto the YZ plane. In the present embodiment, it is assumed that the load applied to the optical fiber cable 5 is the smallest when the angles A _θ and B _θ with _respect to the Z axis are 0 °.

Then, the control unit 3, the angle A _theta, B _theta and length A _R, B _R and stores the correlated angular threshold and distance threshold, the calculated angle A _theta, B _theta and length A _R , B _R is equipped with determination unit 33 whether exceeds a respective threshold, and a service life calculation unit 34 that calculates the lifetime of the optical fiber cable 5. As shown in FIGS. 3 and 4, the angle threshold and the distance threshold are stored as the range of the tip coordinates of the straight lines LA and LB extending from the origin O for each position of the specific points A and B. It can be expressed by polar coordinates using the lengths A _R and B _{R of} LA and LB and the angles A _θ and B _θ from the coordinate axes.
The determination result by the determination unit 33 is displayed on a display unit such as a monitor (not shown).

Further, the control device 3 determines the amount of damage given to the optical fiber cable 5 at each of the specific points A and B based on the calculated lengths A _R and B _{R of} the straight lines LA and LB and the angles A _θ and B _θ. Is calculated by the following formula.
_{D1 = Fra (A R) +} Fθa (A θ)
_{D2 = Fra (B R) +} Fθb (B θ)

here,
D1: damage amount at the connection portion 41 with the optical fiber cable 5,
D2: Damage amount at an intermediate position of the optical fiber cable 5,
A _R : distance from the origin O of the connecting portion 41 with the optical fiber cable 5,
A _θ : An angle of a straight line LA drawn between the connection portion 41 with the optical fiber cable 5 and the origin O with respect to the Z axis on the YZ plane,
B _R : distance from the origin O at an intermediate position of the optical fiber cable 5,
B _θ : An angle of the straight line LB drawn between the midpoint of the optical fiber cable 5 and the origin O with respect to the Z axis on the YZ plane,
Fra, Frb: a function for calculating the amount of damage based on the distances A _R , B _R ,
Fθa, Fθb: Functions that calculate the damage amount based on the angles A _θ and B _θ .

Ｌ＝Ｈ−Ｄ ・・・（２）
ここで、
Ｌ：残り寿命、
Ｈ：総合寿命、
Ｄ：光ファイバケーブルに与える１サイクル間のダメージ量、
Ｄ′ｉ＝Ｄ１＋Ｄ２、
ｎ＝1サイクル間のサンプリング回数
である。 Further, the control device 3 calculates the remaining life L of the optical fiber cable 5 by the life calculation unit 34 using the mathematical expressions (1) and (2) based on the calculated damage amounts D1 and D2, and displays it on the display unit. To do.

L = HD (2)
here,
L: remaining life,
H: Total life,
D: Amount of damage given to the optical fiber cable during one cycle,
D'i = D1 + D2,
n is the number of samplings during one cycle.

The operation of the robot system 1 according to the present embodiment configured as described above will be described below.
According to the robot system 1 according to the present embodiment, as shown in FIGS. 5 and 6, when the operation of the robot body 2 is started in accordance with the teaching program taught in advance, the control device 3 waits T seconds later. The posture S of the robot body 2 is calculated (step S1), and in the posture S, the coordinates of the specific points A and B in the exit coordinate system are calculated (step S2).

Then, based on the calculated coordinates, a particular point A, the distance A _R from B to the origin O of the exit coordinate _system, B _R and calculated respectively (step S3). Further, the angles A _θ and B _θ from the Z axis on the YZ plane of the exit coordinate system are calculated (step S4).

Next, the life calculation unit 34 executes a life calculation routine (step S5). In the life calculation routine, the damage amount D′ i is calculated using the calculated distances A _R and B _R and the angles A _θ and B _θ (step S51), and the calculated damage amount D′ i is integrated. (Step S52). Then, it is determined whether or not one cycle is completed (step S53), and if not completed, the process returns to the main routine. When finished, the remaining life L is calculated (step S54), displayed on the monitor (step S55), and the process returns to the main routine.

Next, it is judged whether or not the calculated distances A _R and B _R and angles A _θ and B _θ respectively exceed the respective threshold values (step S6). If they do not exceed the respective threshold values, the steps from step S1 are repeated. .. On the other hand, when it is determined in step S6 that each threshold is exceeded, the fact is displayed on the display unit (step S7), and the operation of the robot body 2 is stopped (step S8).

As described above, according to the robot system 1 of the present embodiment, when the angles A _θ , B _θ and the distances A _R , B _R calculated by the angle calculation unit 32 exceed the respective thresholds, the fact is notified. Since it is notified by being displayed on the display unit, by changing the operation program or the control based on the determination result, the triaxial wrist unit 25 can be used within a range in which the optical fiber cable 5 is not damaged. Is enabled, the life of the optical fiber cable 5 can be stabilized, and the maintenance frequency can be reduced. Further, by predicting the angles A _θ and B _θ after T seconds, it is possible to notify the damage before the damage.

In particular, the angles A _θ and B _θ are considered to represent the amount of twist of the optical fiber cable 5 at the positions of the specific points A and B, and the optical fiber cable 5 is twisted at the connection portion 41 of the optical fiber cable 5. It is easily damaged by. Therefore, it is possible to stabilize the life of the optical fiber cable 5 by taking measures such as changing the operation so as not to damage the optical fiber cable 5 by determining whether or not the angle threshold value is exceeded and notifying it.

Further, the distances A _R and B _R are considered to represent the pulling and compressing of the optical fiber cable 5 at the positions of the specific points A and B, and the optical fiber cable 5 is located at an intermediate position of the optical fiber cable 5. It is easily damaged by tension and compression. Therefore, it is possible to stabilize the life of the optical fiber cable 5 by taking measures such as changing to an operation that does not damage the optical fiber cable 5 by determining and notifying whether the distance threshold value is exceeded.

Further, according to the present embodiment, the remaining life L of the optical fiber cable 5 is calculated based on the calculated distances A _R and B _R and the angles A _θ and B _θ , and is displayed on the display unit. The remaining life L thus obtained has an advantage that the damage to the optical fiber cable 5 can be more objectively grasped, and the operation program can be corrected based on the remaining life L.

In the present embodiment, a particular point A from the origin O of the exit coordinate system, a straight line LA drawn to B, the length of the LB _(distance) A R, _{B R} and YZ plane projected straight LA, and LB It is determined whether or not the damage amount D′ i of the optical fiber cable 5 is large based on both the angles A _θ and B _θ from the Z coordinate axis. Instead, if it is desired to determine the damage due to the twist, the angle is determined. a _theta, B _theta only, in particular tensile, distance if you want to determine the damage due to compression a _R, may be determined only by B _R.

Further, in the present embodiment, as a result of the determination by the determination unit 33, if the distances A _R , B _R or the angles A _θ , B _θ exceed the threshold value, this is notified, but instead of this, When the distances A _R , B _R or the angles A _θ , B _θ reach a threshold value, the control device 3 controls each wrist element 26, 27, 28 of the robot body 2 so as not to exceed the threshold value. You can

Further, in the present embodiment, as the notifying unit, the one that is displayed on the screen by using the display unit is exemplified, but instead of this, a unit that notifies by sound may be adopted.
Moreover, although the optical fiber cable 5 is illustrated and described as a filament, it is not limited to this.

In the present embodiment, the distance _A R, a function to calculate the amount of damage D'i based on _{B R} Fra, Frb and angle A _theta, function to calculate the amount of damage D'i based on the B _{θ Fθa,} the Fθb Although the damage amount D'i is calculated using the above, the damage amount D'i may be obtained by collating with a database instead. Also, machine learning may be applied.

1 Robot system 2 Robot body 3 Controller 4 Laser processing tool (end effector)
5 Optical fiber cable (striated body)
24 Second Arm (Arm)
26 first wrist element 27 second wrist element 28 third wrist element 31 distance calculation unit 32 angle calculating section 33 judging unit A, B specific point A _theta, B _theta angle A _{R, B R} length (distance)
L4 4th axis (1st axis)
L5 5th axis (2nd axis)
L6 6th axis (3rd axis)
LA, LB straight line

Claims (7)

A robot body and a control device for controlling the robot body,
The robot body has a first wrist element rotatably supported at a tip of an arm about a first axis along a longitudinal axis of the arm, and a second wrist element intersecting the first axis with the first wrist element. A second wrist element rotatably supported about an axis and a third wrist element rotatably supported on the second wrist element about a third axis intersecting the second axis,
The linear body wired through the inside of the arm is fixed to the third wrist element from the linear body outlet provided in the first wrist element via an aerial path outside the robot body. Connected to the end effector
In the orthogonal coordinate system, in which the control device has one coordinate axis extending in the direction along the first axis with the linear body outlet as an origin, a straight line connecting the linear body outlet and a specific point of the linear body is formed. An angle calculation unit that calculates an angle around the coordinate axis with reference to a position where the load applied to the linear body is a line projected on a plane orthogonal to the coordinate axis, and the angle calculated by the angle calculation unit A robot system including a determination unit that determines whether or not the absolute value of is greater than a predetermined angle threshold.   The control device includes a distance calculation unit that calculates a distance between the linear body outlet and a specific point of the linear body, the determination unit, the distance calculated by the distance calculation unit, to the angle. The robot system according to claim 1, wherein it is determined whether or not a predetermined predetermined distance threshold has been exceeded.   The robot system according to claim 1, wherein the control device controls the robot main body within an angle range in which the angle does not exceed the angle threshold value.   The robot system according to claim 1 or 2, wherein the control device includes an informing unit that informs that the angle has exceeded the angle threshold value.   The robot system according to claim 2, wherein the control device controls the robot main body within a distance range in which the distance does not exceed the distance threshold.   The robot system according to claim 2, wherein when the distance is determined to exceed the distance threshold value, the control device includes a notification unit that notifies that effect. The said control apparatus memorize | stores the said angle sequentially calculated by the said angle calculation part, and calculates the life of the said linear body based on the time-sequential angle memorize | stored, The claim 1 or claim 2 statement. Robot system.

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