JP6926904B2 - Robot abnormality judgment device - Google Patents

Description

The present invention relates to an abnormality determining device for determining an abnormality of a robot.

Conventionally, when it is determined that any of the sliding members including the rolling bearing and the sealing member has deteriorated, the rolling bearing and the sealing member are based on the frequency analysis result of the vibration generated when the joint is rotated. There is an abnormality determination device that identifies which of the above is deteriorated (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-59970

By the way, in the abnormality determination device described in Patent Document 1, although it is specified which of the rolling bearing and the seal member is deteriorated, it is said that the deterioration is caused by an external factor such as a robot collision or noise. It does not consider erroneous judgment.

The present invention has been made to solve such a problem, and a main object thereof is to provide a robot abnormality determination device capable of determining whether an abnormality is caused by an external factor or an abnormality caused by an internal factor.

The first means for solving the above problems is
An abnormality determination device that determines abnormalities in a robot equipped with multiple joints.
A torque acquisition unit that acquires a torque when rotating each joint and a torque correlation amount including a parameter that correlates with the torque.
When the torque correlation amount of each joint acquired by the torque acquisition unit is larger than the threshold value corresponding to each joint, the first determination unit determines that the abnormality is present.
When the first determination unit determines that the joint is abnormal in a plurality of joints within a predetermined period, it is determined that the abnormality is due to an external factor, and the first determination unit determines that the abnormality is abnormal in only one joint within the predetermined period. The second determination unit, which determines that the abnormality is due to an internal factor when it is determined to be
To be equipped.

According to the above configuration, the abnormality determination device determines the abnormality of the robot having a plurality of joints. The torque acquisition unit acquires the torque when rotating the joint and the torque correlation amount including the parameters correlating with the torque. As parameters that correlate with torque, the current flowing through the motor that drives the joint, the rotational acceleration of the motor, the ratio of these to the reference value, and the like can be adopted.

Here, the first determination unit determines that the abnormality is abnormal when the torque correlation amount of each joint acquired by the torque acquisition unit is larger than each threshold value corresponding to each joint. Therefore, if the torque correlation amount becomes larger than the threshold value due to internal factors such as scratches on the sliding members at the joints or foreign matter mixed between mechanical parts, it is determined to be abnormal. Will be done. In addition, the torque correlation amount may become larger than the threshold value due to external factors such as robot collision and noise, and it may be determined to be abnormal. These external factors can be not only an abnormal factor of one joint but also an abnormal factor of a plurality of joints at the same time.

In this regard, when the second determination unit determines that the joints are abnormal in a plurality of joints within a predetermined period, it is determined that the abnormality is due to an external factor. That is, when an abnormality occurs in a plurality of joints within a predetermined period, it can be determined that the abnormality is not due to an internal factor of each joint but an abnormality due to an external factor. Further, when the second determination unit determines that the abnormality is found only in one joint by the first determination unit within a predetermined period, it is determined that the abnormality is due to an internal factor. That is, if an abnormality occurs in only one joint within a predetermined period, it can be determined that the abnormality is not due to an external factor but an abnormality due to an internal factor of one joint. Therefore, the robot abnormality determination device can determine whether the abnormality is due to an external factor or an internal factor.

Specifically, in the second means, when the first determination unit determines that an abnormality is present in any of the joints at a predetermined timing, the second determination unit includes the predetermined timing for the predetermined period. When a joint other than the joint determined to be abnormal is determined to be abnormal by the first determination unit, it is determined to be an abnormality due to an external factor. According to such a configuration, when the first determination unit determines that an abnormality is present in any of the joints at a predetermined timing, it is possible to start determining whether or not the abnormality is due to an external factor. Therefore, it is not always necessary to determine whether or not an abnormality has occurred due to an external factor, and it can be executed when an abnormality occurs in any of the joints.

In the third means, the robot includes three or more of the joints, and the second determination unit is abnormal in a plurality of joints that are not adjacent to each other by the first determination unit within the predetermined period. On condition that it is determined, it is determined that the abnormality is due to an external factor.

When an abnormality occurs in one joint of the robot, the abnormality may affect the joint adjacent to that joint. In that case, an abnormality caused by an internal factor of one joint may be erroneously determined to be an abnormality caused by an external factor.

In this regard, according to the above configuration, it is determined that the abnormality is due to an external factor, provided that the second determination unit determines that the joints are abnormal in a plurality of joints that are not adjacent to each other within a predetermined period. It is judged. Therefore, even if the first determination unit determines that the joints are abnormal in a plurality of joints within a predetermined period, if the joints determined to be abnormal are adjacent to each other, it is an abnormality due to an external factor. Is not determined. Therefore, even when the influence of an abnormality occurring in one joint extends to adjacent joints, it is possible to suppress erroneous determination that the abnormality is due to an external factor.

The fourth means is
An abnormality determination device that determines abnormalities in a robot equipped with multiple joints.
A torque acquisition unit that acquires a torque when rotating each joint and a torque correlation amount including a parameter that correlates with the torque.
The torque interrelated amounts of the respective joints obtained by the torque obtaining section, said determined to be abnormal if greater than the threshold value corresponding to each joint, the much larger than the respective determination value is smaller than the threshold value a first determination unit determines that and the are quasi abnormal if not name greater than the threshold value,
When it is determined by the first determination unit that the joints are abnormal or quasi-abnormal within a predetermined period, it is determined that the abnormality is due to an external factor, and within the predetermined period, the first determination unit 1 The second judgment unit, which determines that the abnormality is due to an internal factor when it is determined that the abnormality is present only in one joint,
To be equipped.

According to the above configuration, the first determination unit determines that it is abnormal when each torque correlation amount acquired by the torque acquisition unit is larger than each threshold value corresponding to each joint. Further, the first determination unit, the torque correlation amount obtained by the torque obtaining section is, it is determined that if we name greater than the size rather and the thresholds than the determination value is smaller than the threshold value is a quasi-abnormal NS. Therefore, the torque amount of correlation, if not name larger than the size rather and the thresholds than the determination value, although not abnormal, as an abnormal state close, be determined to be quasi-abnormal can.

Then, when the second determination unit determines that the joints are abnormal or quasi-abnormal by the first determination unit within a predetermined period, it is determined that the abnormality is due to an external factor. That is, when an abnormality or a quasi-abnormality occurs in a plurality of joints within a predetermined period, it can be determined that the abnormality is not due to an internal factor of each joint but an abnormality due to an external factor. Even if a quasi-abnormality occurs in a plurality of joints within a predetermined period, it is unlikely that the abnormality is caused by an internal factor of each joint, so that it can be determined that the abnormality is caused by an external factor.

Further, when the second determination unit determines that the abnormality is found only in one joint by the first determination unit within a predetermined period, it is determined that the abnormality is due to an internal factor. That is, if an abnormality occurs in only one joint within a predetermined period, it can be determined that the abnormality is not due to an external factor but an abnormality due to an internal factor of one joint. Therefore, the robot abnormality determination device can determine whether the abnormality is due to an external factor or an internal factor.

Specifically, in the fifth means, when the second determination unit is determined by the first determination unit to be abnormal or quasi-abnormal in any of the joints at a predetermined timing, the predetermined timing When the joint other than the joint determined to be abnormal or quasi-abnormal within the predetermined period including the above is determined to be abnormal or quasi-abnormal by the first determination unit, it is due to an external factor. Judge as abnormal. According to such a configuration, when the first determination unit determines that any joint is abnormal or quasi-abnormal at a predetermined timing, it starts determining whether or not the abnormality is due to an external factor. be able to. Therefore, it is not always necessary to determine whether or not an abnormality has occurred due to an external factor, and it can be executed when an abnormality or a quasi-abnormality occurs in any of the joints.

In the sixth means, the robot includes three or more of the joints, and the second determination unit is abnormal in a plurality of joints that are not adjacent to each other by the first determination unit within the predetermined period. On condition that it is determined to be a quasi-abnormality, it is determined to be an abnormality due to an external factor.

According to the above configuration, on condition that the second judgment unit determines that the joints that are not adjacent to each other by the first judgment unit are abnormal or quasi-abnormal within a predetermined period, the abnormality is caused by an external factor. It is determined that there is. Therefore, even if the first determination unit determines that a plurality of joints are abnormal or quasi-abnormal within a predetermined period, the joints determined to be abnormal or quasi-abnormal are adjacent to each other. In some cases, it is not determined to be abnormal due to an external factor. Therefore, even when the influence of an abnormality occurring in one joint extends to adjacent joints, it is possible to suppress erroneous determination that the abnormality is due to an external factor.

In the seventh means, the torque acquisition unit repeatedly acquires the torque correlation amount in a predetermined cycle, and the predetermined period is one or more times and three times or less of the predetermined cycle.

According to the above configuration, the torque correlation amount is repeatedly acquired by the torque acquisition unit at a predetermined cycle. The predetermined period is one time or more and three times or less the predetermined cycle. Therefore, it is possible to determine that an abnormality (quasi-abnormality) has occurred in a plurality of joints at substantially the same time, and it is possible to accurately determine that an abnormality has occurred due to an external factor.

The magnitude of the torque correlation amount of each joint changes according to the operating state of the robot. Further, when the robot is not operating normally, the torque correlation amount may become an inappropriate value.

In this regard, in the eighth means, the threshold value is set based on the operating state of the robot when the robot is normally operated. Therefore, the robot abnormality determination device can appropriately determine whether the abnormality is due to an external factor or an internal factor regardless of the operating state of the robot.

In the ninth means, the abnormal position acquisition unit that acquires the rotation position of each joint when it is determined to be abnormal by the first determination unit, and the second determination unit determines that the abnormality is due to an internal factor. When the plurality of rotation positions acquired by the abnormal position acquisition unit are equal to each other, it is determined that the joint is abnormal due to component damage, and the plurality of rotation positions acquired by the abnormal position acquisition unit are mutually equal. It is provided with a third determination unit that determines that the abnormality is due to the inclusion of foreign matter when they are not equal.

According to the above configuration, the abnormal position acquisition unit acquires the rotational position of the joint when the first determination unit determines that the joint is abnormal. In the case of an abnormality due to damage to a part, the rotation position determined to be an abnormality does not change. On the other hand, in the case of an abnormality due to the inclusion of foreign matter, the rotation position determined to be abnormal may change due to the movement of the foreign matter.

In this regard, in a joint determined by the third determination unit to be abnormal due to an internal factor, when a plurality of rotation positions acquired by the abnormality position acquisition unit are equal to each other, it is an abnormality due to component damage. It is determined that there is. That is, when a plurality of rotation positions acquired by the abnormal position acquisition unit are equal to each other, it can be determined that the abnormality is not due to foreign matter mixing but due to damage to parts. In addition, in a joint determined by the third determination unit to be abnormal due to an internal factor, when a plurality of rotation positions acquired by the abnormality position acquisition unit are not equal to each other, an abnormality due to foreign matter contamination occurs. It is determined that there is. That is, when the plurality of rotation positions acquired by the abnormal position acquisition unit are not equal to each other, it can be determined that the abnormality is not due to damage to parts but due to the inclusion of foreign matter. Therefore, in the robot abnormality determination device, it is possible to determine whether the abnormality due to an internal factor is an abnormality due to damage to a part or an abnormality due to foreign matter contamination. The case where the plurality of rotation positions acquired by the abnormal position acquisition unit are equal to each other includes the case where the plurality of rotation positions can be regarded as substantially equal to each other.

In the tenth means, the abnormal position acquisition unit that acquires the rotation position of each joint when it is determined to be abnormal by the first determination unit, and the second determination unit determines that the abnormality is due to an internal factor. When the difference amount of the plurality of rotation positions acquired by the abnormal position acquisition unit is smaller than the predetermined amount, it is determined that the joint is abnormal due to damage to a part, and the difference amount is larger than the predetermined amount. In some cases, it is provided with a third determination unit that determines that the abnormality is due to the inclusion of foreign matter.

According to the above configuration, in the joint determined by the third determination unit to be abnormal due to an internal factor, the difference amount of the plurality of rotation positions acquired by the abnormality position acquisition unit is larger than the predetermined amount. If it is small, it is judged to be abnormal due to damage to parts. That is, when the difference amount of the plurality of rotation positions acquired by the abnormal position acquisition unit is smaller than the predetermined amount, it can be determined that the abnormality is not due to the inclusion of foreign matter but due to damage to parts. Further, in the joint determined by the third determination unit to be abnormal due to an internal factor, when the difference amount is larger than the predetermined amount, it is determined that the joint is abnormal due to foreign matter contamination. That is, when the difference amount is larger than the predetermined amount, it can be determined that the abnormality is not due to damage to parts but due to the inclusion of foreign matter. Therefore, in the robot abnormality determination device, it is possible to determine whether the abnormality due to an internal factor is an abnormality due to damage to a part or an abnormality due to foreign matter contamination.

The figure which shows the outline of a robot and a controller. The perspective view which shows the bearing. The block diagram which shows the function of a robot and a controller. The flowchart which shows the procedure of abnormality determination of 1st Embodiment. A time chart showing changes in the current ratio for the first joint. A time chart showing changes in the current ratio for the second joint. A time chart showing a mode in which an abnormality has occurred in the first joint. A time chart showing a mode in which an abnormality has occurred in the second joint. A time chart showing a mode in which an abnormality has occurred in the third joint. The flowchart which shows the procedure of abnormality determination of 2nd Embodiment.

(First Embodiment)
Hereinafter, the first embodiment embodied in the control device of the vertical articulated robot will be described with reference to the drawings. The robot of this embodiment is used as an industrial robot in an assembly system such as a machine assembly factory.

First, an outline of the robot 10 will be described with reference to FIG.

The robot 10 is configured as, for example, a 6-axis vertical articulated robot. The robot 10 includes a base 11, a shoulder portion 13, a lower arm 15, a first upper arm 16A, a second upper arm 16B, a wrist portion 17, and a flange 18. The shoulder portion 13 (first rotating portion) is rotatably supported in the horizontal direction by the base 11 (J1 axis). The lower arm 15 (second rotating portion) is rotatably supported in the vertical direction by the shoulder portion 13 (J2 axis). The first upper arm 16A (third rotating portion) is rotatably supported in the vertical direction by the lower arm 15 (J3 axis). The second upper arm 16B (fourth rotating portion) is rotatably supported by the first upper arm 16A (J4 axis). The wrist portion 17 (fifth rotating portion) is rotatably supported in the vertical direction by the second upper arm 16B (J5 axis). The flange 18 (sixth rotating portion) is rotatably supported by the wrist portion 17 (J6 axis).

The base 11, the shoulder portion 13, the lower arm 15, the first upper arm 16A, the second upper arm 16B, the wrist portion 17, and the flange 18 function as arms of the robot 10. An end effector (hand) is attached to the flange 18 at the tip of the arm, although not shown. Each joint (each rotating portion) of the robot 10 is driven (rotated) by each corresponding motor 31 (see FIG. 3).

Each joint is provided with a bearing. FIG. 2 shows one bearing 20.

As shown in the figure, the bearing 20 (rolling bearing) is, for example, a well-known ball bearing (ball bearing), and includes an inner ring 21, an outer ring 22, a rolling element 23, and the like. A plurality of rolling elements 23 (balls or rollers) are provided between the inner ring 21 and the outer ring 22. Each rolling element 23 slides by rolling contact with the rolling surface 21a formed on the inner ring 21 and the rolling surface 22a formed on the outer ring 22. As the bearing 20, a cross roller bearing or the like can also be adopted.

FIG. 3 is a block diagram showing the functions of the robot 10 and the controller 70.

The controller 70 (robot abnormality determination device) is configured as a microcomputer including a CPU, ROM, RAM, drive circuit, input / output interface, and the like. Then, the controller 70 realizes the functions of the torque acquisition unit 71, the first determination unit 72, and the second determination unit 73. Although the configuration corresponding to one joint is shown in the figure, the motor 31, the position detection unit 34, and the current detection unit 35 are provided in each joint.

Motors 31 provided at each joint are connected to the controller 70. These motors 31 are driven based on a control signal from the controller 70.

A position detection unit 34 (for example, an encoder) that detects the rotation position of the joint is connected to the controller 70. Rotational position information of each joint is input to the controller 70 from each position detection unit 34. A current detection unit 35 that detects the value of the current flowing through the motor 31 is connected to the controller 70. The current value of each motor 31 is input to the controller 70 from each current detection unit 35. The controller 70 feedback-controls the rotation position of each motor 31 based on the rotation position information input from the position detection unit 34 and the current value input from the current detection unit 35.

The torque acquisition unit 71 calculates (acquires) the current ratio (torque correlation amount) of each motor 31 as a parameter that correlates with the torque when rotating each joint based on the current value input from the current detection unit 35. do. Specifically, the torque acquisition unit 71 calculates the current ratio [%] of the motor 31 by dividing the input current value of the motor 31 by the preset rated current of the motor 31.

The first determination unit 72 determines that it is abnormal when the current ratio of each joint calculated by the torque acquisition unit 71 is larger than each threshold value corresponding to each joint. The magnitude of the current flowing through the motor 31 and the magnitude of the current ratio change according to the operating state of the robot 10. Further, when the robot 10 is not operating normally, the current ratio may become an inappropriate value. Therefore, each of the above threshold values is set based on the operating state of the robot 10 when the robot 10 is normally operated, specifically, the current command value of each motor 31. Each threshold value is set to a smaller value as the current command value of each motor 31 is smaller.

Here, the current ratio is due to internal factors such as scratches on the rolling surfaces 21a and 22a of the bearing 20 at the joint and foreign matter mixed between the inner ring 21 (outer ring 22) and the rolling element 23. When is larger than the threshold value, it is determined to be abnormal. Further, the current ratio may become larger than the threshold value due to an external factor such as the robot 10 colliding with the equipment or the operator or noise may be added to the signal, and it may be determined to be abnormal. These external factors can be not only an abnormal factor of one joint but also an abnormal factor of a plurality of joints at the same time.

On the other hand, in the present embodiment, the second determination unit 73 determines that the abnormality is due to an external factor when the first determination unit 72 determines that the joints are abnormal within a predetermined period of time. When the first determination unit 72 determines that the abnormality is present in only one joint within the predetermined period Te, it is determined that the abnormality is due to an internal factor. Specifically, the controller 70 executes the abnormality determination shown in FIG. 4 at regular intervals (for example, every few seconds).

First, the current ratio of each joint in a certain period is calculated (S11). For example, as shown for the J1 axis in FIG. 5, the current value detected by the current detection unit 35 at each moment is divided by the rated current to calculate the current ratio at each moment in a certain period. As shown in FIG. 6, the current ratio is calculated in the same manner for the J2 axis to the J6 axis.

Subsequently, it is determined whether or not there is a joint in which the current ratio> the threshold value during a certain period (S12). This threshold value is set based on the operating state of the robot 10 when the robot 10 is normally operated, specifically, the current command value of each motor 31. Then, when the current ratio> the threshold value, it is determined to be abnormal. In this determination, when it is determined that there is no joint whose current ratio> threshold value within a certain period (S12: NO), this series of processing is terminated (END).

On the other hand, in the determination of S12, when it is determined that there is a joint in which the current ratio> the threshold value within a certain period (S12: YES), whether or not the current ratio> the threshold value is satisfied at almost the same time in the other joints. Judgment (S13). The period deemed to be substantially simultaneous (predetermined period Te) is a predetermined cycle in which the current detection unit 35 detects the current value at each moment, that is, a predetermined cycle in which the torque acquisition unit 71 calculates the current ratio at each moment, and the current ratio> threshold value. Up to 1 cycle before and after the cycle (predetermined timing) (3 cycles in total). This predetermined period is, for example, several ms to several tens of ms.

In the determination of S13, when it is determined that the current ratio> the threshold value at approximately the same time in the other joints (S13: YES), it is determined that the abnormality is due to an external factor (S14). Then, it notifies that an abnormality has occurred due to an external factor (S15). This notification can be executed by display by a display device, notification by voice, lighting of a warning light, or the like. After that, this series of processing is completed (END).

Further, in the determination of S13, when it is determined that the current ratio> the threshold value is not satisfied at approximately the same time in the other joints (S13: NO), it is determined that the abnormality is due to an internal factor (S16). Then, the joint in which the abnormality has occurred due to an internal factor is notified (S17). After that, this series of processing is completed (END).

The process of S11 corresponds to the process of the torque acquisition unit 71, the process of S12 corresponds to the process of the first determination unit 72, and the processes of S12 to S14 and S16 correspond to the process of the second determination unit 73. Equivalent to.

FIG. 7 is a time chart showing a mode in which an abnormality has occurred in the first joint (J1 axis). As shown in the figure, at the timing t1, the current ratio is larger than the first threshold value, and it is determined that the current ratio is abnormal. Further, at the timing t2, the current ratio is larger than the second threshold value, and it is determined that the current ratio is abnormal. The smaller the current command value of the motor 31, the smaller the first threshold value and the second threshold value are set, so that the values are different from each other.

FIG. 8 is a time chart showing a mode in which an abnormality has occurred in the second joint (J2 axis). As shown in the figure, at the timing t1, since the current ratio is not larger than the third threshold value, it is not determined to be abnormal. Further, at the timing t2, the current ratio is larger than the fourth threshold value, and it is determined that the current ratio is abnormal.

FIG. 9 is a time chart showing a mode in which an abnormality has occurred in the third joint (J3 axis). As shown in the figure, at the timing t1, since the current ratio is not larger than the fifth threshold value, it is not determined to be abnormal. Further, at the timing t2, the current ratio is larger than the sixth threshold value, and it is determined that the current ratio is abnormal.

Therefore, at the timing t1, it is determined that the abnormality is present only in the first joint, and it is determined that the abnormality due to an internal factor has occurred in the first joint. At the timing t2, it is determined that the first, second, and third joints are abnormal, and it is determined that an abnormality has occurred due to an external factor.

The present embodiment described in detail above has the following advantages.

-The first determination unit 72 determines that the abnormality is found when the current ratio of each joint acquired by the torque acquisition unit 71 is larger than each threshold value corresponding to each joint. Therefore, if the current ratio becomes larger than the threshold value due to internal factors such as scratches on the sliding members at the joints or foreign matter mixed between mechanical parts, it is determined to be abnormal. be able to. Further, the current ratio may become larger than the threshold value due to an external factor such as a collision of the robot 10 or noise, and it may be determined to be abnormal. These external factors can be not only an abnormal factor of one joint but also an abnormal factor of a plurality of joints at the same time.

-When the second determination unit 73 determines that the joints are abnormal in a plurality of joints within the predetermined period Te, it is determined that the abnormality is due to an external factor (timing t2). That is, when an abnormality occurs in a plurality of joints within a predetermined period of time, it can be determined that the abnormality is not due to an internal factor of each joint but an abnormality due to an external factor. Further, when the second determination unit 73 determines that the abnormality is abnormal only in one joint by the first determination unit 72 within the predetermined period Te, it is determined that the abnormality is due to an internal factor (timing t1). That is, when an abnormality occurs in only one joint within a predetermined period of time, it can be determined that the abnormality is not due to an external factor but due to an internal factor of one joint. Therefore, the controller 70 can determine whether the abnormality is due to an external factor or an internal factor.

When the second determination unit 73 determines that an abnormality is found in any of the joints by the first determination unit 72 at the timing t2 (S12: YES), the second determination unit 73 determines that the abnormality is within the predetermined period Te including the timing t2. When the joint other than the determined joint is determined to be abnormal by the first determination unit 72 (S13: YES), it is determined to be abnormal due to an external factor (S14). According to such a configuration, when the first determination unit 72 determines at timing t2 that an abnormality is present in any of the joints, it is possible to start determining whether or not the abnormality is due to an external factor. Therefore, it is not always necessary to determine whether or not an abnormality has occurred due to an external factor (S12: NO), and it can be executed when an abnormality occurs in any of the joints.

-The torque acquisition unit 71 repeatedly acquires the current ratio in a predetermined cycle (several ms to several tens of ms). The predetermined period Te is three times the predetermined cycle. Therefore, it is possible to determine that an abnormality has occurred in a plurality of joints at substantially the same time, and it is possible to accurately determine that an abnormality has occurred due to an external factor. Further, the period deemed to be substantially simultaneous (predetermined period Te) is up to one cycle before and after the cycle (predetermined timing) at which the current ratio> the threshold value in the predetermined cycle in which the torque acquisition unit 71 calculates the current ratio at each moment. ..

-The first threshold value and the second threshold value for determining the abnormality are set based on the operating state of the robot 10 when the robot 10 is operated normally. Therefore, the controller 70 can appropriately determine whether the abnormality is due to an external factor or an internal factor regardless of the operating state of the robot 10.

It should be noted that the above embodiment can be modified and implemented as follows. The same parts as those in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

-When an abnormality occurs in one joint of the robot 10, the joint adjacent to that joint may be affected by the abnormality. In that case, an abnormality caused by an internal factor of one joint may be erroneously determined to be an abnormality caused by an external factor.

Therefore, the second determination unit 73 may determine that the abnormality is due to an external factor, provided that the first determination unit 72 determines that the joints are abnormal in a plurality of joints that are not adjacent to each other within a predetermined period of time. good. That is, instead of the process of S13 in FIG. 4, it may be determined whether or not the current ratio> the threshold value is satisfied at substantially the same time even for other joints that are not adjacent to each other. According to such a configuration, even if the first determination unit 72 determines that the joints are abnormal in a plurality of joints within a predetermined period of time, if the joints determined to be abnormal are joints adjacent to each other, it is external. It is not judged to be an abnormality due to a factor. Therefore, even when the influence of an abnormality occurring in one joint extends to adjacent joints, it is possible to suppress erroneous determination that the abnormality is due to an external factor.

(Second Embodiment)
Hereinafter, the second embodiment will be described focusing on the differences from the first embodiment. In the present embodiment, the controller 70 executes the abnormality determination of FIG. 10 instead of the abnormality determination of FIG. Other points are the same as those of the first embodiment.

The controller 70 executes the abnormality determination shown in FIG. 10 at regular intervals (for example, every few seconds).

The processing of S20 to S24 is the same as the processing of S11 to S15 of FIG.

In the determination of S21, when it is determined that there is no joint whose current ratio> threshold value during a certain period (S21: NO), whether or not there is a joint whose current ratio> determination value during a certain period. (S25). This determination value is set to a value smaller than the above threshold value, and is set to a value that can be determined to be in a state close to an abnormality (quasi-abnormality) although it is not an abnormality. The determination value is set based on the operating state of the robot 10 when the robot 10 is normally operated, specifically, the current command value of each motor 31. Then, when the current ratio> the determination value, it is determined to be quasi-abnormal.

In the determination of S25, when it is determined that there is no joint for which the current ratio> the determination value within a certain period (S25: NO), this series of processing is terminated (END).

On the other hand, in the determination of S25, when it is determined that there is a joint in which the current ratio> the determination value within a certain period (S25: YES), is the current ratio> the determination value at approximately the same time in the other joints? Whether or not it is determined (S26). The period deemed to be substantially simultaneous (predetermined period Te) is the same as that of the first embodiment.

In the determination of S26, when it is determined that the current ratio> the determination value at approximately the same time in the other joints (S26: YES), it is determined that the abnormality is due to an external factor (S23). On the other hand, in the determination of S26, when it is determined that the current ratio> the determination value is not satisfied at approximately the same time in the other joints (S26: NO), this series of processes is terminated (END).

Further, in the determination of S22, when it is determined that the current ratio> the threshold value is not satisfied at the other joints at substantially the same time (S22: NO), whether or not the current ratio> the determination value is satisfied at the other joints at the same time. Judgment (S27). The process of S27 is the same as the process of S26.

In the determination of S27, when it is determined that the current ratio> the determination value at approximately the same time in the other joints (S27: YES), it is determined that the abnormality is due to an external factor (S23). On the other hand, in the determination of S27, when it is determined that the current ratio> the determination value is not satisfied at approximately the same time in the other joints (S27: NO), it is determined that the abnormality is due to an internal factor (S28). The processing of S28 and S29 is the same as the processing of S16 and S17 of FIG.

The processing of S20 corresponds to the processing of the torque acquisition unit 71, the processing of S21 and S25 corresponds to the processing of the first determination unit 72, and the processing of S21 to S23, S25, S26, S27 and S28 is the first. 2 Corresponds to the processing as the determination unit 73.

The present embodiment described in detail above has the following advantages. Here, only the advantages different from the first embodiment will be described.

-The first determination unit 72 determines that the abnormality is abnormal when each current ratio acquired by the torque acquisition unit 71 is larger than each threshold value corresponding to each joint. Further, the first determination unit 72, and the current ratio obtained by the torque obtaining section 71, a quasi-abnormal if not name larger than the size rather and the thresholds than the determination value is smaller than the threshold determination Will be done. Therefore, each current ratio, if not name larger than the size rather and the thresholds than the determination value, although not abnormal, as an abnormal state close, it can be determined that the quasi-abnormal ..

-When the second determination unit 73 determines that the joints are abnormal or quasi-abnormal by the first determination unit 72 within a predetermined period of time Te, it is determined that the abnormality is due to an external factor. That is, when an abnormality or a quasi-abnormality occurs in a plurality of joints within a predetermined period of time, it can be determined that the abnormality is not due to an internal factor of each joint but an abnormality due to an external factor. Even if a quasi-abnormality occurs in a plurality of joints within a predetermined period of time, it is unlikely that the abnormality is caused by an internal factor of each joint, so that it can be determined that the abnormality is caused by an external factor.

-When the second determination unit 73 determines that the abnormality is abnormal only in one joint by the first determination unit 72 within a predetermined period of time Te, it is determined that the abnormality is due to an internal factor. That is, when an abnormality occurs in only one joint within a predetermined period of time, it can be determined that the abnormality is not due to an external factor but an abnormality due to an internal factor of one joint. Therefore, the controller 70 can determine whether the abnormality is due to an external factor or an internal factor.

When the second determination unit 73 is determined by the first determination unit 72 to be abnormal or quasi-abnormal in any of the joints at a predetermined timing (timing t2) (S21: YES or S25: YES). , When a joint other than a joint determined to be abnormal or quasi-abnormal within a predetermined period Te including a predetermined timing is determined to be abnormal or quasi-abnormal by the first determination unit 72 (S22: If YES, S26: YES, or S27: YES), it is determined that the abnormality is due to an external factor. According to such a configuration, when the first determination unit 72 determines that any of the joints is abnormal or quasi-abnormal in the predetermined timing, the determination of whether or not the abnormality is due to an external factor is started. can do. Therefore, it is not always necessary to determine whether or not an abnormality has occurred due to an external factor (S21: NO and S25: NO), and it can be executed when an abnormality or a quasi-abnormality occurs in any of the joints. ..

It should be noted that the above embodiment can be modified and implemented as follows. The same parts as those in each of the above embodiments are designated by the same reference numerals, and the description thereof will be omitted.

The second determination unit 73 determines that the abnormality is due to an external factor, provided that the first determination unit 72 determines that the joints that are not adjacent to each other are abnormal or quasi-abnormal within a predetermined period of time. You may judge. According to the above configuration, even if the first determination unit 72 determines that a plurality of joints are abnormal or quasi-abnormal within a predetermined period of time, the joints determined to be abnormal or quasi-abnormal If the joints are adjacent to each other, it is not determined to be an abnormality due to an external factor. Therefore, even when the influence of an abnormality occurring in one joint extends to adjacent joints, it is possible to suppress erroneous determination that the abnormality is due to an external factor.

Further, each of the above embodiments can be modified and implemented as follows. The same parts as those in each of the above embodiments are designated by the same reference numerals, and the description thereof will be omitted.

-For the predetermined period Te, 1 time or more and 3 times or less of the predetermined period (several ms to several tens of ms) in which the torque acquisition unit 71 calculates the current ratio at each moment, 1 time or more and 5 times or less of the predetermined period, etc. May be set to.

-The controller 70 can also execute the abnormality determination shown in FIGS. 4 and 10 every three times or every five times the predetermined cycle.

-The threshold value for determining an abnormality can be set to a constant value regardless of the operating state of the robot 10. However, the threshold value is set corresponding to each joint (each motor 31).

When the controller 70 is determined by the second determination unit 73 to be an abnormality due to an internal factor, the abnormality due to the internal factor is either an abnormality due to damage to a part (damage to a sliding member or a gear) or a foreign substance is mixed in (damage to a sliding member or a gear). It may be determined whether the abnormality is caused by foreign matter mixed between the machine parts. That is, the controller 70 is determined by the first determination unit 72 to acquire the rotation position of each joint when it is determined to be abnormal, and the second determination unit 73 to determine that the abnormality is due to an internal factor. If the plurality of rotation positions acquired by the abnormal position acquisition unit are equal to each other, it is determined that the joint is abnormal due to component damage, and if the plurality of rotation positions acquired by the abnormal position acquisition unit are not equal to each other, a foreign object is formed. A third determination unit that determines that the abnormality is due to mixing may be provided.

According to the above configuration, the abnormal position acquisition unit acquires the rotational position of each joint when the first determination unit 72 determines that the joint is abnormal. In the case of an abnormality due to damage to a part, the rotation position determined to be an abnormality does not change. On the other hand, in the case of an abnormality due to the inclusion of foreign matter, the rotation position determined to be abnormal may change due to the movement of the foreign matter.

In this regard, in a joint determined by the second determination unit 73 to be an abnormality due to an internal factor, when a plurality of rotation positions acquired by the abnormality position acquisition unit are equal to each other, an abnormality due to component damage Is determined to be. That is, when a plurality of rotation positions acquired by the abnormal position acquisition unit are equal to each other, it can be determined that the abnormality is not due to foreign matter mixing but due to damage to parts. Further, in a joint determined by the third determination unit 73 to be an abnormality due to an internal factor, when a plurality of rotation positions acquired by the abnormality position acquisition unit are not equal to each other, an abnormality due to foreign matter contamination Is determined to be. That is, when the plurality of rotation positions acquired by the abnormal position acquisition unit are not equal to each other, it can be determined that the abnormality is not due to damage to parts but due to the inclusion of foreign matter. Therefore, the controller 70 can determine whether the abnormality due to an internal factor is an abnormality due to component damage or an abnormality due to foreign matter contamination. The case where the plurality of rotation positions acquired by the abnormal position acquisition unit are equal to each other includes the case where the plurality of rotation positions can be regarded as substantially equal to each other.

-The controller 70 is caused by component damage when the difference amount of a plurality of rotation positions acquired by the abnormal position acquisition unit is smaller than a predetermined amount in the joint determined by the second determination unit 73 to be abnormal due to an internal factor. A third determination unit may be provided, which determines that the abnormality is due to foreign matter mixing when the difference amount is larger than a predetermined amount.

According to the above configuration, in the joint determined by the second determination unit 73 to be abnormal due to an internal factor by the third determination unit, the difference amount of the plurality of rotation positions acquired by the abnormality position acquisition unit is more than a predetermined amount. If it is also small, it is determined that the abnormality is due to damage to the parts. That is, when the difference amount of the plurality of rotation positions acquired by the abnormal position acquisition unit is smaller than the predetermined amount, it can be determined that the abnormality is not due to the inclusion of foreign matter but due to damage to parts. Further, in the joint determined by the third determination unit 73 to be abnormal due to an internal factor, when the difference amount is larger than the predetermined amount, it is determined that the abnormality is due to foreign matter contamination. .. That is, when the difference amount is larger than the predetermined amount, it can be determined that the abnormality is not due to damage to parts but due to the inclusion of foreign matter. Therefore, the controller 70 can determine whether the abnormality due to an internal factor is an abnormality due to component damage or an abnormality due to foreign matter contamination.

-The command value (torque correlation amount) of the current by the controller 70 can be used instead of the current value detected by the current detection unit 35. Further, instead of comparing the current ratio and the threshold value to determine the abnormality, it is also possible to compare the current value (torque correlation amount) of the motor 31 with the threshold value corresponding to the current value to determine the abnormality. .. Similarly, the rotational acceleration (torque correlation amount) of the motor 31 and the corresponding threshold value, the torque of the motor 31 and the corresponding threshold value, the joint torque and the corresponding threshold value, and these can be compared to determine an abnormality. ..

-It is also possible to execute the abnormality determination of the robot 10 by a terminal device such as a personal computer connected to the controller 70. In that case, the controller 70 may store the current value detected by the current detection unit 35 and transmit the stored current value to the terminal device. Then, the terminal device (robot abnormality determination device) may realize the functions of the torque acquisition unit 71, the first determination unit 72, and the second determination unit 73.

-The robot 10 is not limited to a vertical articulated robot, but may be a horizontal articulated robot or the like.

10 ... Robot, 31 ... Motor, 35 ... Current detection unit, 70 ... Controller, 71 ... Torque acquisition unit, 72 ... First determination unit, 73 ... Second determination unit.

Claims (10)

An abnormality determination device that determines abnormalities in a robot equipped with multiple joints.
A torque acquisition unit that acquires a torque when rotating each joint and a torque correlation amount including a parameter that correlates with the torque.
When the torque correlation amount of each joint acquired by the torque acquisition unit is larger than the threshold value corresponding to each joint, the first determination unit determines that the abnormality is present.
When the first determination unit determines that the joint is abnormal in a plurality of joints within a predetermined period, it is determined that the abnormality is due to an external factor, and the first determination unit determines that the abnormality is abnormal in only one joint within the predetermined period. The second determination unit, which determines that the abnormality is due to an internal factor when it is determined to be
A robot abnormality determination device equipped with. When the first determination unit determines that any joint is abnormal at a predetermined timing, the second determination unit determines that the joint is abnormal within the predetermined period including the predetermined timing. The robot abnormality determination device according to claim 1, wherein when the first determination unit determines that the joints other than the joints are abnormal, the abnormality is determined to be due to an external factor. The robot has three or more of the joints.
1. The second determination unit determines that the abnormality is due to an external factor, provided that the first determination unit determines that the joints are abnormal in a plurality of joints that are not adjacent to each other within the predetermined period. The robot abnormality determination device described in 1. An abnormality determination device that determines abnormalities in a robot equipped with multiple joints.
A torque acquisition unit that acquires a torque when rotating each joint and a torque correlation amount including a parameter that correlates with the torque.
The torque interrelated amounts of the respective joints obtained by the torque obtaining section, said determined to be abnormal if greater than the threshold value corresponding to each joint, the much larger than the respective determination value is smaller than the threshold value a first determination unit determines that and the are quasi abnormal if not name greater than the threshold value,
When it is determined by the first determination unit that the joints are abnormal or quasi-abnormal within a predetermined period, it is determined that the abnormality is due to an external factor, and within the predetermined period, the first determination unit 1 The second judgment unit, which determines that the abnormality is due to an internal factor when it is determined that the abnormality is present only in one joint,
A robot abnormality determination device equipped with. When the first determination unit determines that any joint is abnormal or quasi-abnormal at a predetermined timing, the second determination unit is said to be abnormal within the predetermined period including the predetermined timing. Or, in claim 4, when a joint other than a joint determined to be quasi-abnormal is determined to be abnormal or quasi-abnormal by the first determination unit, it is determined to be abnormal due to an external factor. The robot abnormality determination device described. The robot has three or more of the joints.
The second determination unit determines that the abnormality is due to an external factor, provided that the first determination unit determines that the joints that are not adjacent to each other are abnormal or quasi-abnormal within the predetermined period. The robot abnormality determination device according to claim 4. The torque acquisition unit repeatedly acquires the torque correlation amount at a predetermined cycle.
The robot abnormality determination device according to any one of claims 1 to 6, wherein the predetermined period is 1 time or more and 3 times or less the predetermined cycle. The robot abnormality determination device according to any one of claims 1 to 7, wherein the threshold value is set based on the operating state of the robot when the robot is normally operated. An abnormal position acquisition unit that acquires the rotation position of each joint when it is determined to be abnormal by the first determination unit, and an abnormal position acquisition unit.
In a joint determined to be abnormal due to an internal factor by the second determination unit, when a plurality of the rotational positions acquired by the abnormal position acquisition unit are equal to each other, it is determined to be an abnormality due to component damage, and the abnormality is determined. A third determination unit that determines that an abnormality is caused by foreign matter when the plurality of rotation positions acquired by the position acquisition unit are not equal to each other.
The robot abnormality determination device according to any one of claims 1 to 8, further comprising. An abnormal position acquisition unit that acquires the rotation position of each joint when it is determined to be abnormal by the first determination unit, and an abnormal position acquisition unit.
In a joint determined to be abnormal due to an internal factor by the second determination unit, when the difference amount of the plurality of rotation positions acquired by the abnormal position acquisition unit is smaller than a predetermined amount, it is an abnormality due to component damage. When the difference amount is larger than the predetermined amount, it is determined that the abnormality is due to the inclusion of foreign matter, and the third determination unit.
The robot abnormality determination device according to any one of claims 1 to 8, further comprising.

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