JP2020069633A - Robot system - Google Patents

Abstract

To provide a robot system, which allows a robot main body to keep operating without incorrect stoppage of the body by a contact stoppage function, without setting load variation patterns in advance, even if the loads which the robot main body deals with vary largely.SOLUTION: A robot system 1 comprises: a robot main body 2; a sensor 21 that detects magnitude of external force applied to the robot main body 2; a control part that controls the robot main body 2; a reference value storage that stores as a reference external force value a value of external force detected by the sensor 21, in an operation state where only own weight of the robot main body 2 and a load which the robot main body 2 deals with act on the robot main body 2; and a determining part that determines that external force other than the own weight and the load acts on the robot main body 2 if an absolute value of a difference between the value of external force detected by the sensor 21 and the reference external force value stored in the reference value storage is larger than a predetermined threshold, during operation of the robot main body 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a robot system.

  BACKGROUND ART Conventionally, there is known a collaborative robot that has a contact stop function that stops when a person touches it, stores a predetermined reference force, and stops the robot when the detected external force is larger than the stored reference force. (For example, refer to Patent Document 1).

JP, 2008-51734, A

In the collaborative robot of Patent Document 1, even if the magnitude of the load handled changes significantly, it is erroneously detected that a large external force exceeding the reference force has acted, and the collaborative robot stops due to the contact stop function. Therefore, if the load change pattern is known, it is necessary to set the load change pattern itself in advance. In this case, there is an inconvenience that it is necessary to perform an operation for presetting a load change pattern.
The present invention provides a robot system in which even if the load handled by the robot body changes significantly, the pattern of load change is not set in advance, and the operation can be continued without erroneous stop by the contact stop function. The purpose is to do.

  One aspect of the present invention is to provide a robot main body, a sensor that detects the magnitude of an external force applied to the robot main body, a control unit that controls the robot main body, the robot main body, its own weight, and the robot main body. In the operating state in which only the load handled by is applied, the reference value storage unit that stores the value of the external force detected by the sensor as the reference external force value, and the sensor detected during the operation of the robot body When the absolute value of the difference between the value of the external force and the reference external force value stored in the reference value storage unit is larger than a predetermined threshold value, an external force other than the own weight and the load acts on the robot body. It is a robot system provided with the determination part which determines that it did.

  According to this aspect, the magnitude of the external force applied to the robot main body is detected by the sensor in the operating state in which only the weight of the robot main body and the load handled by the robot main body are applied, and the value of the detected external force is used as the reference external force value. It is stored in the reference value storage unit. Then, during operation of the robot body, the absolute value of the difference between the value of the external force detected by the sensor and the reference external force value stored in the reference value storage unit is calculated, and if the absolute value of the difference is greater than the threshold value. In addition, the determining unit determines that an external force other than its own weight and the load to be handled is acting on the robot body.

  That is, the reference external force value is the magnitude of the external force detected each time by the sensor in the operating state in which only the weight of the robot body and the load handled by the robot body are applied at each position of the operation of the robot body. Can be used. Therefore, even when the load handled by the robot main body changes significantly, it is not necessary to acquire the reference external force value in advance, and the operation can be continued without being erroneously stopped by the contact stop function.

In the above aspect, the reference value storage unit may update the reference external force value at a plurality of locations on the operation path of the robot body.
With this configuration, the sensor detects and detects the magnitude of external force applied to the robot body in the operating state where only the weight of the robot body and the load handled by the robot body act at multiple points on the movement path of the robot body. The value of the applied external force is stored in the reference value storage unit as the reference external force value. As a result, even if the pattern of changes in external force at each position along the movement path of the robot body is not constant, if the load handled by the robot body changes significantly, the reference external force values actually detected at multiple locations With the contact stop function, it is possible to continue the operation without accidentally stopping.

Further, in the above aspect, the reference value storage unit may store the reference external force value when the robot body is in a stopped state or a low speed operation state.
With this configuration, it is possible to easily achieve an operation state in which only the dead weight of the robot body and the load handled by the robot body act on the robot body in a stopped state or a low-speed operation state.

Further, in the above aspect, the sensor may be any one of at least one of a force sensor, a torque sensor, and a skin sensor incorporated in the robot body or added to the robot body.
With this configuration, the external force acting on the robot body can be accurately detected in the operating state in which only the weight of the robot body and the load handled by the robot body act.

Further, in the above aspect, the reference value storage unit may store the reference external force value every time the robot body manually operated by the operator enters a stopped state or a low speed operation state.
With this configuration, when the operator is operating the robot body manually, such as during teaching operation or hand guidance that directly operates the robot body, if the load changes significantly, the robot body is in a stopped state or By storing the reference external force value detected by the sensor in the reference value storage unit each time the low-speed operation state is entered, it is not necessary to obtain the reference external force value in advance, and the contact stop function operates without causing an accidental stop. You can keep going.

Further, in the above aspect, the reference value storage unit controls the robot body at any teaching point set in the teaching program during execution of the teaching program, or at predetermined time intervals or at predetermined movement distances. The reference external force value may be stored as the stopped state or the low speed operation state.
With this configuration, the robot main body is brought into a stopped state or a low-speed operation state at a suitable time during execution of the teaching program, and the reference external force value is detected and stored. As a result, when the load handled by the robot main body changes significantly, it is possible to continue the operation without accidentally stopping by the contact stop function, even if the reference external force value is not acquired in advance in the teaching work.

Further, in the above aspect, the reference value storage unit may automatically update the reference external force value when the robot body is in a stopped state or a low speed operation state.
Further, in the above aspect, the reference value storage unit is in an operating state when a person is not in contact with the robot body and only the dead weight of the robot body and the load handled by the robot body are operating. In, the reference external force value may be stored.

  According to the present invention, even when the load handled by the robot body changes significantly, it is possible to continue the operation without accidentally stopping by the contact stop function without presetting the change pattern of the load. Play.

It is the whole block diagram which shows the robot system which relates to one execution form of this invention. FIG. 3 is a block diagram showing a control device provided in the robot system of FIG. 1. It is a figure which shows the initial position of the work which equips a robot with a filament by the robot system of FIG. It is a figure which shows the 1st position which gripped the linear body by lowering a hand from the state of FIG. It is a figure which shows the intermediate position which raises a hand and lifts a filamentous body from the state of FIG. It is a figure which shows the 2nd position which fully lifted the linear body from the state of FIG. It is a figure which shows the state which started the fitting of the linear body to the robot in the 2nd position of FIG. It is a figure which shows the 3rd position which lowered the hand a little from the 2nd position of FIG. It is a figure which shows the state which equipped the robot of the linear body in the 3rd position of FIG. 10 is a graph showing the external force value detected by the sensor, the update position of the reference external force value, and the change in the reference external force value + threshold in the operation of FIGS. 3 to 9. FIG. 8 is a diagram showing a state in which a work having a small weight is slightly lifted and a reference external force value is updated in multi-product palletizing which is another application of the robot system in FIG. 1. FIG. 12 is a diagram showing a state in which the reference external force value is updated by switching to a work having a large weight in FIG. 11. It is a flowchart explaining the fitting method of a filamentous body.

A robot system 1 according to an embodiment of the present invention will be described below with reference to the drawings.
The robot system 1 according to the present embodiment is a system including a collaborative robot (hereinafter, robot body) 2 that can operate by sharing a work area with a human without a safety fence.

As shown in FIG. 1, the robot system 1 includes a robot body 2 and a control device 3 that controls the robot body 2.
Although the robot main body 2 is a vertical articulated robot in the example shown in FIG. 1, other arbitrary forms may be adopted.

  The robot body 2 is provided with a sensor 21 that detects the magnitude of external force. As the sensor 21, at least one of a force sensor, a torque sensor, and a skin sensor incorporated in the robot body 2 or added to the robot body 2 may be adopted. In the present embodiment, the sensor 21 is installed below the first axis of the robot body 2 to simplify the description.

  In addition to the weight of the robot main body 2 itself and the load handled by the robot main body 2, the sensor 21 applies a load to the robot main body 2 due to, for example, an operator or the like contacting the robot main body 2 or another peripheral object. The external force of can be detected.

The control device 3 includes a processor and a memory.
The control device 3 controls the operation of the robot body 2 when executing a teaching program taught in advance, or the operator operates a teaching operation panel (not shown) to input an operation input, thereby causing the robot body 2 to operate. A control unit (processor) 31 for controlling to execute a jog feed operation is provided.

In addition, as shown in FIG. 2, the control device 3 controls the external force detected by the sensor 21 in a specific operation state in which only the weight of the robot body 2 and the load handled by the robot body 2 act on the robot body 2. A reference value storage unit (memory) 32 that stores the value as a reference external force value, and a difference calculation unit that calculates the absolute value of the difference between the external force value detected by the sensor 21 during the operation of the robot body 2 and the reference external force value. A (processor) 33 and a determination unit (processor) 34 that determines whether or not the absolute value of the difference calculated by the difference calculation unit 33 is larger than a predetermined threshold value is provided.
The control unit 31 has a contact stop function of stopping the operation of the robot body 2 and a function of reducing the robot speed when the determination unit 34 determines that the absolute value of the difference is larger than a predetermined threshold value. ..

The specific operation state is a stopped state or a low speed operation state of the robot body 2, and the timing of storing the reference external force value in the reference value storage unit 32 varies depending on the operation mode of the robot body 2.
For example, in the operation mode in which the robot body 2 is manually operated by operating the teaching operation panel, a sensor is used every time the robot body 2 is stopped or in a low speed operation state while the robot body 2 is being jogged. The external force value detected by 21 may be stored as the reference external force value. Alternatively, it may be stored at any timing according to the operator's instruction.

  In addition, for example, in an operation mode in which the robot body 2 is automatically operated according to a teaching program, a command for causing the robot body 2 to be in a stopped state or a low-speed operating state is taught to a plurality of appropriate teaching points of the teaching program, The specific operation state may be realized at the plurality of points above, and the external force value detected by the sensor 21 at that time may be stored as the reference external force value.

The operation of the robot system 1 according to the present embodiment configured as described above will be described below.
As a case in which the robot system 1 according to the present embodiment is used to perform work in which the magnitude of the load handled by the robot body 2 changes significantly, for example, as shown in FIGS. 3 to 9, a long flexible line is used. The work of mounting the strip 4 on another device 5 such as another robot can be mentioned.

In this work, the robot body 2 has a hand 22 at its tip, and the robot body 2 is operated according to a teaching program.
The operation of the robot main body 2 is as follows. First, as shown in FIG. 3, the hand 22 is lowered to the first position in the pallet 6 as shown in FIG. The end of the filamentous body 4 accommodated in 6 is grasped by the hand 22. Next, with the end of the filamentous body 4 being held, as shown in FIG. 6, the hand 22 is lifted to a sufficiently high second position, and a standby state is waited at that position to wait for an operator's operation input. To do.

  Then, when the operator inputs an operation, as shown in FIG. 8, the hand 22 is moved to a third position lower than the second position, and the operator waits for an operation input again at that position. Set to standby state. At the time of descending to the third position, the end of the filamentous body 4 held by the hand 22 is released, and the work is completed by returning to the initial position.

  In this operation, as shown in FIG. 10, from the initial position of FIG. 3 to the gripping of the filamentous body 4 at the first position of FIG. 4, the sensor 21 has the weight of the robot body 2 and the hand 22 as shown in FIG. Only the weight acts, and the value of the external force detected by the sensor 21 at the initial position is stored in the reference value storage unit 32 as the first reference external force value.

  Next, since the linear body 4 in the pallet 6 is gradually lifted while the robot main body 2 operates from the first position where the hand 22 holds the linear body 4 to the second position in the first position. The value of the external force detected by the sensor 21 gradually increases. The external force value is detected by the sensor 21 at predetermined time intervals, the difference between the detected external force value and the reference external force value stored in the reference value storage unit 32 is calculated by the difference calculation unit 33, and the calculated difference is calculated. The determination unit 34 determines whether or not the absolute value exceeds a predetermined threshold. When the absolute value of the difference exceeds the threshold value, the operation of the robot body 2 is stopped by the contact stop function of the control unit 31.

  In the present embodiment, the robot body 2 is stopped, teaching points are provided at each of the initial position, the first position to the third position, and as shown in FIG. 5, from the first position to the second position. A teaching point is provided for each position where the absolute value of the difference between the two does not exceed the threshold value. The number of teaching points is arbitrary. Then, a command for realizing the specific operation state is taught to each teaching point, and a command for updating the value of the reference value storage unit 32 with the value of the external force detected by the sensor 21 at that time as a new reference external force value is given. Be taught.

  Next, as shown in FIG. 7, at the second position, since the lowering of the suspended linear body 4 to the other device 5 is started, the linear body 4 supported by the hand 22 is started. Is gradually reduced, and the external force value detected by the sensor 21 becomes smaller. In this case, the weight change of the filamentous body 4 due to the fitting operation at the second position does not exceed the threshold value.

  Then, when the fitting of the filamentous body 4 at the second position is completed, the operator inputs an operation to the teaching operation panel, whereby the reference external force value is updated again as shown in FIG. After that, the robot body 2 moves from the second position to the third position shown in FIG. Thereby, the slack of the filamentous body 4 for fitting in the third position is formed.

  When the robot body 2 moves to the third position, stops, and enters a standby state, the external force value detected by the sensor 21 is updated as a new reference external force value in the reference value storage unit 32. As shown in FIG. 9, it is assumed that the weight change of the filamentous body 4 due to the fitting at the third position does not exceed the threshold value. As shown in FIG. 10, after the linear body 4 is released at the third position, the reference external force value is updated again, and the updated reference external force value is used to return to the initial position.

  As described above, according to the robot system according to the present embodiment, in the work in which the magnitude of the load handled by the robot body 2 continuously changes, the magnitude of the load changes beyond the threshold for operating the contact stop function. Even in such a case, there is an advantage that the pattern of the change of the load can be set in advance and the operation can be continued without being erroneously stopped by the contact stop function.

  That is, since the external force value detected by the sensor 21 is updated as the reference external force value of the contact stop function in a state where the specific operation state is realized during the operation of the robot body 2, the load change pattern is set in advance. No need. Further, there is an advantage that the work can be continued while maintaining the contact stop function even when the load change pattern is not fixed.

  In the present embodiment, in the operation of executing the teaching program, the specific operation state is realized at the teaching point appropriately set in the teaching program, and the external force value detected by the sensor 21 is automatically updated as the reference external force value. However, instead of this, in the work of manually operating the robot main body 2 by the operator operating the teaching operation panel, the sensor 21 detects the robot main body 2 each time the robot main body 2 is stopped or operated at low speed. The reference external force value may be updated with the external force value.

  Further, in the present embodiment, as shown in FIG. 10, the specific operation state is realized and the reference external force value is updated at the seven teaching points, but instead, it is updated. The frequency may be increased. As a result, the threshold value can be made smaller and the sensitivity of the contact stopping function can be increased.

  In addition, when a person is not in contact with the robot body 2, and in a specific operation state in which only the weight of the robot body 2 and the load handled by the robot body 2 act on the robot body 2, the reference external force value is stored. With this, a more accurate reference external force value can be recorded. This makes it possible to reduce the threshold value and increase the sensitivity of the contact stopping function. When the person is not in contact with the robot body 2, it is preferable to use a laser area sensor or a vision sensor installed around the robot body 2 that can detect the approach of the person.

  Further, in the present embodiment, the work in which the load continuously changes, as in the case of moving up and down the soft filamentous body 4, has been described as an example, but the present invention is not limited to this, and FIG. As shown in FIG. 12, it may be applied when the weights of the works W1 and W2 to be gripped change.

  For example, when holding and holding two types of works W1 and W2 of different weights as in a multi-product palletizing work, as shown in FIGS. 11 and 12, each work W1 and W2 is held by a hand 22. The specific operation state may be realized in a slightly raised state, and the reference external force value may be updated with the external force value detected by the sensor 21 at that time.

  Further, the present invention can be similarly applied to the case where the work of three or more kinds of weight is changed. In this case, the weight difference between all the workpieces may be smaller than the threshold value, or when defining the order of holding patterns, the weight difference between adjacent workpieces may be smaller than the threshold value. In this case, the sensitivity of contact stop can be increased by making the threshold value smaller.

Further, in the present embodiment, the following method of fitting the filamentous body 4 is also disclosed.
Conventionally, the fitting of the filaments has been performed sequentially from the lower side of other devices while an operator lifts a long and heavy filament. However, if a large number of filaments are bundled, or if a filament for large current is included, or if a sheet metal for fixing the filaments and a switchboard are installed. In the case of handling a strip, the weight of the strip becomes large and the burden on the operator is large.

  On the other hand, the method for mounting the filamentous body 4 is such that the hand 22 attached to the tip of the robot body 2 grips and lifts one end of the filamentous body 4 and the other end side of the filamentous body 4. From the step where the operator performs a part of the work of fitting the filamentous body 4 to another device 5 and the operation of the robot body 2 up to the position where the filamentous body 4 is loosened by the amount necessary for the next fitting operation. The step of lowering the hand 22 is repeated.

  Specifically, as shown in FIG. 13, the hand 22 is lowered to the first position in the pallet 6 as shown in FIG. 4 from the state of being placed in the initial position (step S1), and the pallet is moved. The end of the filamentous body 4 accommodated in 6 is grasped by the hand 22 (step S2). Next, with the end of the filamentous body 4 held, as shown in FIG. 6, the hand 22 is lifted to a sufficiently high second position (step S3), and the operator's operation input is made at that position. A standby state for waiting is set (step S4).

  Then, when the operator inputs an operation, as shown in FIG. 8, the hand 22 is moved to a third position lower than the second position (step S5), and at that position, the operator again moves the hand 22. A standby state waiting for an operation input is set (step S6). At the time of descending to the third position, the end of the filamentous body 4 gripped by the hand 22 is released, and the work is completed by returning to the initial position (step S7).

  According to the method of fitting the filamentous body 4, the filamentous body 4 in the state of being lifted by the robot body 2 can be equipped from the lower portion to another device 5, and at that time, the filamentous body 4 can be mounted. Since the weight is supported by the robot body 2, it is not necessary for the operator to lift the filamentous body 4, which is advantageous in that the burden on the operator can be reduced.

  Then, every time the fitting of the lower part of the filamentous body 4 is completed, the robot main body 2 operates so as to form a slack for fitting the filamentous body 4 on the upper side. It is possible to successively equip the filamentous body 4 without lifting.

  Then, in this case, from the initial position of FIG. 3 to the gripping of the filamentous body 4 at the first position of FIG. 4, as shown in FIG. In the initial position, the value of the external force detected by the sensor 21 is stored in the reference value storage unit 32 as the first reference external force value.

  Next, since the linear body 4 in the pallet 6 is gradually lifted while the robot main body 2 operates from the first position where the hand 22 holds the linear body 4 to the second position in the first position. The value of the external force detected by the sensor 21 gradually increases. The external force value is detected by the sensor 21 at predetermined time intervals, the difference between the detected external force value and the reference external force value stored in the reference value storage unit 32 is calculated by the difference calculation unit 33, and the calculated difference is calculated. The determination unit 34 determines whether or not the absolute value exceeds a predetermined threshold. When the absolute value of the difference exceeds the threshold value, the operation of the robot body 2 is stopped by the contact stop function of the control unit 31.

  In the present embodiment, the robot body 2 is stopped, teaching points are provided at each of the initial position, the first position to the third position, and as shown in FIG. 5, from the first position to the second position. A teaching point is provided for each position where the absolute value of the difference between the two does not exceed the threshold value. The number of teaching points is arbitrary. Then, a command for realizing the specific operation state is taught to each teaching point, and a command for updating the value of the reference value storage unit 32 with the value of the external force detected by the sensor 21 at that time as a new reference external force value is given. Be taught.

  Next, as shown in FIG. 7, at the second position, since the lowering of the suspended linear body 4 to the other device 5 is started, the linear body 4 supported by the hand 22 is started. Is gradually reduced, and the external force value detected by the sensor 21 becomes smaller. In this case, the weight change of the filamentous body 4 due to the fitting operation at the second position does not exceed the threshold value.

  Then, when the fitting of the filamentous body 4 at the second position is completed, the operator inputs an operation to the teaching operation panel, whereby the reference external force value is updated again as shown in FIG. After that, the robot body 2 moves from the second position to the third position shown in FIG. Thereby, the slack of the filamentous body 4 for fitting in the third position is formed. Further, the teaching operation panel is not limited to the teaching operation panel provided on the robot body 2 itself, and a separately installed wired or wireless remote controller may be used.

  When the robot body 2 moves to the third position, stops, and enters a standby state, the external force value detected by the sensor 21 is updated as a new reference external force value in the reference value storage unit 32. As shown in FIG. 9, it is assumed that the weight change of the filamentous body 4 due to the fitting at the third position does not exceed the threshold value. As shown in FIG. 10, after the linear body 4 is released at the third position, the reference external force value is updated again, and the updated reference external force value is used to return to the initial position.

1 Robot System 2 Robot Main Body 21 Sensor 31 Control Unit (Processor)
32 reference value storage (memory)
34 Judgment unit (processor)

Claims (8)

The robot body,
A sensor for detecting the magnitude of the external force applied to the robot body,
A control unit for controlling the robot body,
A reference value storage unit that stores the value of the external force detected by the sensor as a reference external force value in an operating state in which only the weight of the robot main body and a load handled by the robot main body act on the robot main body;
During operation of the robot body, when the absolute value of the difference between the value of the external force detected by the sensor and the reference external force value stored in the reference value storage unit is larger than a predetermined threshold value, A robot system comprising: a determination unit that determines that an external force other than the self-weight and the load acts on the robot body.   The robot system according to claim 1, wherein the reference value storage unit updates the reference external force value at a plurality of locations on an operation path of the robot body.   The robot system according to claim 1, wherein the reference value storage unit stores the reference external force value when the robot body is in a stopped state or a low speed operation state.   The robot according to any one of claims 1 to 3, wherein the sensor is at least one of a force sensor, a torque sensor, and a skin sensor incorporated in the robot body or added to the robot body. system.   The robot according to claim 1 or 2, wherein the reference value storage unit stores the reference external force value every time the robot body manually operated by an operator is brought into a stopped state or a low speed operation state. system.   The reference value storage unit sets the robot main body to a stopped state or a low speed operation state at any teaching point set in the teaching program or at a predetermined time interval or a predetermined moving distance during execution of the teaching program. The robot system according to claim 1, wherein the reference external force value is stored.   The robot system according to claim 1, wherein the reference value storage unit automatically updates the reference external force value when the robot body is in a stopped state or a low speed operation state.   The reference value storage unit stores the reference external force value when a person is not in contact with the robot body, and in an operating state in which only the weight of the robot body and the load handled by the robot body are operating. The robot system according to any one of claims 1 to 7, which stores the information.

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