JP6492474B2 - Sliding member deterioration judgment system - Google Patents

Description

  The present invention relates to a deterioration determination system that determines the presence or absence of deterioration of a sliding member that slides as a joint rotates in a robot.

  Conventionally, an articulated robot having a plurality of joints has been put to practical use as an industrial robot. In such a robot, each joint is provided with a motor (servo motor), and each joint is rotated by driving the motor.

  Each joint of the robot is provided with a sliding member that slides as the joint rotates (see, for example, Patent Document 1). The sliding member has an annular shape surrounding the rotation axis of the joint, and a plurality of sliding members are provided at each joint. As the sliding member, a rolling bearing that smoothly rotates the joint and a sealing member that performs sealing to prevent oil leakage are provided. The rolling bearing has an outer ring, an inner ring, and a plurality of rolling elements provided between the two rings, and slides when the rolling element is in rolling contact with the rolling surface of the outer ring or the inner ring. On the other hand, the seal member slides by sliding the entire circumference of the seal member against a mating member (for example, the output shaft of the motor).

  Since the sliding member is a member that deteriorates with the passage of time, repeated rotation of the joint, or the like, it is necessary to periodically inspect the sliding member. When inspecting the sliding member, for example, a person in charge at the site makes a judgment on whether or not the sliding member has deteriorated depending on his / her own sense. However, in the method of determining the presence or absence of deterioration based on the sense of the person in charge, it can be considered that the determination is likely to vary. Also, at sites where there is no person in charge of maintaining the robot, it is conceivable that the sliding members will not be inspected regularly. In this case, the sliding members will deteriorate without knowing and the robot will stop suddenly. There is also a risk.

JP 2012-45673 A

  By the way, when the sliding member is deteriorated due to foreign matter mixed in or flaking, the sliding state of the sliding member changes, for example, the sliding resistance of the sliding member increases. It is possible that this will occur. In that case, it is conceivable that a change also occurs in the drive characteristics (for example, the load characteristics of the motor) of the motor that rotates the joint while resisting the sliding resistance of the sliding member.

  Therefore, focusing on this point, there is provided a detection means for detecting the drive characteristics of the motor, and a deterioration determination system for determining whether or not the sliding member has deteriorated based on the drive characteristics of the motor detected by the detection means. Can be considered. According to such a system, unlike the above-described method of determining the presence or absence of deterioration based on the sense of the person in charge, there is no variation in the deterioration judgment, and even if there is no person in charge of maintaining the robot, the deterioration occurs. Since the determination is made, it is possible to avoid a situation in which the deterioration proceeds without knowing and the robot suddenly stops.

  However, in the above-described system, it is possible to determine that any one of the plurality of sliding members provided in the joint has deteriorated. It is impossible to determine (specify) until the sliding member is deteriorated. Therefore, when it is determined that the sliding member has deteriorated, the sliding member provided in the joint is visually checked to identify which sliding member has deteriorated. There is a need. However, the specific work is expected to take a lot of time and effort, and improvements are required.

  The present invention has been made in view of the above circumstances, and provides a sliding member deterioration determination system capable of relatively easily specifying a deteriorated sliding member when the sliding member is deteriorated. The main purpose is to provide it.

  In order to solve the above-mentioned problems, a slide member deterioration determination system according to a first aspect of the present invention comprises a motor for rotationally driving a joint and an annular shape surrounding the rotation shaft of the joint, and slides as the joint rotates. A plurality of sliding members, wherein the plurality of sliding members include a bearing member made of a rolling bearing that slides when the rolling element is in rolling contact with the rolling surface, and the entire circumference is in sliding contact with the counterpart member. Applied to a robot including a seal member that slides, and based on the drive characteristics of the motor, the deterioration that determines whether any of the plurality of sliding members has deteriorated A vibration detecting means for detecting vibration generated when the joint is rotated by the motor when the deterioration determining means determines that any of the sliding members has deteriorated; In the vibration detection means The frequency analysis means for performing frequency analysis on the detected vibration and the frequency spectrum of the vibration obtained by the frequency analysis have an amplitude at a specific frequency determined corresponding to the bearing member larger than a predetermined value. A determination means for determining whether or not a frequency peak exists; and, when it is determined that the frequency peak exists in the frequency spectrum of the vibration, the sliding member that has deteriorated is identified as the bearing member, When it is determined that the frequency peak does not exist in the frequency spectrum of the vibration, the slide member having the deterioration is specified as the seal member.

  In general, a robot joint is provided with a plurality of sliding members, and the plurality of sliding members include a bearing member (rolling bearing) and a seal member. In the bearing member, the rolling element slides in contact with the rolling surface as the joint rotates, so if the rolling surface is damaged due to flaking or contamination, the rolling element will remove the damaged part. It is conceivable that a large vibration is generated every time it passes. Therefore, when the bearing member is deteriorated (damaged), it is considered that a large vibration is periodically generated when the joint is rotationally driven by the motor. On the other hand, since the entire circumference of the sealing member slides in a sliding contact with the mating member, when the sealing member is damaged, the damaged portion always contacts the mating member. Become. For this reason, even if the seal member is deteriorated (scratched), it is considered that no significant vibration is periodically generated when the joint is rotationally driven due to the deterioration.

  Therefore, in the present invention, focusing on these points, a specifying means for specifying whether the deteriorated sliding member is a bearing member or a seal member is provided. That is, in the present invention, when it is determined that any sliding member has deteriorated, vibration generated when the joint is rotationally driven by the motor is detected, and frequency analysis is performed on the detected vibration. . Then, it is determined whether or not there is a frequency peak whose amplitude is greater than a predetermined value at a specific frequency in the frequency spectrum of vibration obtained by frequency analysis. If there is a frequency peak in the frequency spectrum of the vibration as a result of this determination, it can be considered that a large vibration is periodically generated when the joint is rotationally driven by the motor. The moving member is identified as a bearing member. On the other hand, when there is no frequency peak in the frequency spectrum of vibration, it can be considered that large vibration is not periodically generated when the joint is rotationally driven by the motor. Identified as a seal member. According to such a configuration, it is specified whether the deteriorated sliding member is a bearing member or a seal member. Therefore, when the sliding member is deteriorated, the deteriorated sliding member is relatively It becomes possible to specify easily.

  In the sliding member deterioration determination system according to the second aspect of the present invention, when the deterioration determining unit determines that the sliding member has deteriorated in the first aspect of the invention, the operation mode of the robot is changed to a normal operation. Switching means for switching from a mode to a constant speed operation mode in which the joint is rotationally driven by the motor at a constant speed, and the vibration detecting means is configured to rotate the joint at a constant speed under the constant speed operation mode. The generated vibration is detected, and the frequency analysis means performs frequency analysis on the detected vibration at the constant speed rotation.

  According to the present invention, the robot operation mode can be switched from the normal operation mode to the constant speed operation mode when it is determined by the deterioration determination means that the sliding member has deteriorated. In the constant speed operation mode, the joint is rotationally driven by the motor at a constant speed. In this case, the vibration generated during the constant speed rotation is detected and the frequency analysis is performed. Here, when the bearing member is deteriorated (damaged), it is considered that a large vibration is generated at a constant period when the joint is rotated at a constant speed. For this reason, it is considered that a frequency peak at a specific frequency tends to appear remarkably in the frequency spectrum of vibration (during constant speed rotation) obtained by the frequency analysis. Therefore, according to the present invention, the above-described configuration for identifying whether the deteriorated sliding member is a bearing member or a seal member based on the presence or absence of a frequency peak can be suitably performed. .

  A sliding member deterioration determination system according to a third invention is applied to an articulated robot having a plurality of the joints in the second invention, and the motor and the plurality of sliding members for each of the joints. The deterioration determining means determines whether or not the sliding member has deteriorated for each joint based on the drive characteristics of each motor, and in the constant velocity operation mode, Of the joints, only the joints determined to be deteriorated in the sliding member by the deterioration determining means are rotated at a constant speed by the motor, and the other joints are rotated by the motor. It is characterized by stopping.

  According to the present invention, in the constant speed operation mode, only the joint (target joint) in which the sliding member has deteriorated among the joints provided in the robot is rotationally driven at a constant speed by the motor, and the other joints The rotation drive by the motor is stopped. In this case, in an articulated robot having a plurality of joints, vibration generated with rotation of the target joint can be suitably detected. Therefore, degradation performed based on the detected vibration (specifically, a frequency spectrum). It is possible to suitably identify the sliding member (identification of the bearing member or the seal member).

  The sliding member deterioration determination system according to a fourth aspect of the present invention is that when any one of the first to third inventions determines that the sliding member is deteriorated by the deterioration determining means. A warning means for warning is provided.

  According to the present invention, when the sliding member is deteriorated, the warning means warns that effect, so that it is possible to quickly take measures such as replacing the deteriorated sliding member with a new one. As a result, it is possible to avoid the inconvenience that the degradation of the sliding member proceeds without knowing and the operation of the robot stops.

  A sliding member deterioration determination system according to a fifth invention is applied to an articulated robot including a plurality of the joints in any one of the first to fourth inventions, and the motor and the motor for each joint. A plurality of sliding members are provided, and the deterioration determining means determines whether or not the sliding members are deteriorated for each joint based on the driving characteristics of the motors. When the deterioration determining means determines that the sliding member has deteriorated in any of the joints, the deterioration determining means includes notifying means for notifying which of the joints is provided.

  According to the present invention, when the sliding member is deteriorated at any one of the joints provided in the robot, it is notified which of the joints is. Therefore, in a robot having a plurality of joints, it is easy to cope with deterioration of the sliding member.

  A sliding member deterioration determination system according to a sixth aspect of the present invention is the first to fifth aspects of the invention, wherein the load information acquisition unit acquires the load information related to the driving load of the motor that rotationally drives the joint; Convergence time acquisition means for acquiring a convergence time until the rotation position of the joint converges to the target position when the joint is rotationally driven by a motor to a predetermined target position, and acquired by the load information acquisition means The motor load information and the convergence time of the motor acquired by the convergence time acquisition means both correspond to the drive characteristics of the motor, and the deterioration determination means converges with the acquired load information of the motor. Based on the time, it is determined whether or not the sliding member has deteriorated.

  By the way, when deterioration occurs in the sliding member, it is considered that the sliding state of the sliding member changes. For example, it is conceivable that the sliding resistance of the sliding member is increased, and in this case, it is considered that the driving load of the motor that rotationally drives the joint against the sliding resistance is increased. Further, depending on the deterioration state of the sliding member, it is considered that the vibration generated when the joint is rotationally driven by the motor increases. In that case, when the joint is rotated to a predetermined target position by the motor, it is considered that the convergence time until the rotational position of the joint converges to the target position becomes long.

  Therefore, in the present invention, paying attention to these points, the load information on the driving load of the motor and the convergence time of the motor are acquired by the acquisition means, respectively, and the sliding member is based on the acquired load information and convergence time of the motor. It is assumed that the deterioration judgment is performed. In this case, for example, when the driving load of the motor becomes larger than a predetermined value, it is determined that the sliding member has deteriorated, or when the motor convergence time becomes longer than the predetermined time, It can be determined that deterioration has occurred. As described above, by performing the deterioration determination of the sliding member based on the two types of motor drive characteristics, it is possible to improve the accuracy of the deterioration determination.

  In any one of the first to sixth inventions, the slide member deterioration determination system according to a seventh aspect of the present invention is such that a plurality of the bearing members are provided in the joint, and the specific frequency is provided for each of the bearing members. Is determined correspondingly, and when it is determined by the determination means that the frequency peak is present in the frequency spectrum of the vibration, peak determination means for determining at which specific frequency the frequency peak exists The specifying means specifies the bearing member corresponding to the specific frequency determined that the frequency peak is present by the peak determining means as the sliding member in which the deterioration has occurred.

  In the case where a plurality of bearing members are provided in the joint, the specific frequency is determined corresponding to each of the bearing members. Therefore, in the present invention, when it is determined that a frequency peak exists in the frequency spectrum of vibration, it is determined at which specific frequency the frequency peak exists, and the bearing member corresponding to the determined specific frequency is deteriorated. It is specified as a sliding member in which is generated. In this case, since the deteriorated sliding member is identified from among the bearing members, the deteriorated sliding member can be identified more easily.

The front view which shows the outline | summary of a robot. (A) is a perspective view which shows a bearing member, (b) is a perspective view which shows a sealing member. The figure which shows the electrical constitution of the deterioration determination system of a sliding member. The flowchart which shows a deterioration determination process. The figure which shows the time-dependent change of a motor load factor. The figure which shows the time-dependent change of the rotation position of a joint. The flowchart which shows a deterioration member specific process. The figure which shows the frequency spectrum of a vibration.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the present invention is embodied as a sliding member deterioration determination system applied to an industrial robot for assembling machines in an assembly line of a machine assembly factory.

  FIG. 1 is a front view showing an outline of the robot. As shown in FIG. 1, the robot 10 is a six-axis robot having six joints K1 to K6. The robot 10 has a first axis J1, a second axis J2, a third axis J3, a fourth axis J4, a fifth axis J5, and a sixth axis J6 as rotation axes (joint axes) of the joints K1 to K6. Yes. In the present embodiment, the robot 10 is installed at a robot installation location such as a floor so that the first axis J1 extends in the vertical direction. In the following description, the vertical direction in FIG. 1 indicates the vertical direction.

  In the robot 10, the base 11 has a fixed portion 12 that is fixed at the robot installation location and a rotating portion 13 that is provided above the fixed portion 12. The rotation unit 13 is rotatable with respect to the fixed unit 12 with a first axis J1 extending in the vertical direction as a rotation center. A lower arm 15 is connected to the upper end portion of the rotating portion 13. The lower arm 15 is rotatable with respect to the rotation unit 13 about a second axis J2 extending in the horizontal direction as a rotation center.

  The upper arm 16 is connected to the tip (upper end) of the lower arm 15. The upper arm 16 is rotatable with respect to the lower arm 15 about a third axis J3 extending in the horizontal direction. The upper arm 16 includes a first upper arm 16A on the proximal end and a second upper arm 16B on the distal end which are divided in the longitudinal direction. Of these arms 16A and 16B, the first upper arm 16A is connected to the lower arm 15. The second upper arm 16B is rotatably connected to the first upper arm 16A with a fourth axis J4 extending in the longitudinal direction of the upper arm 16 as a rotation center.

  A wrist 17 is provided at the tip of the upper arm 16 (specifically, the second upper arm 16B). The wrist portion 17 is rotatably connected to the second upper arm 16B with a fifth axis J5 extending in the horizontal direction as a rotation center. The wrist portion 17 is provided with a hand portion 18 for attaching a work, a tool or the like. The hand portion 18 is coupled to the wrist portion 17 so as to be rotatable in the torsional direction with the sixth axis J6 being the center line as a rotation center.

  As described above, the robot 10 includes a plurality of (specifically six) components (the rotation unit 13, the lower arm 15, and the first upper arm) that are rotatable about the axes J1 to J6. 16A, 2nd upper arm 16B, wrist part 17, hand part 18). In this case, each of these components rotates with the rotation of the joints K1 to K6 around the axes J1 to J6.

  Each joint K1 to K6 is provided with a motor 21 (servo motor). By driving these motors 21, the joints K <b> 1 to K <b> 6 rotate, and as a result, each component rotates.

  The joints K1 to K6 are provided with sliding members 22 and 23 that slide with the rotation of the joints K1 to K6, respectively. The sliding members 22 and 23 have an annular shape (ring shape) surrounding the rotation axes J1 to J6 of the joints K1 to K6, and a plurality of the sliding members 22 and 23 are provided in each of the joints K1 to K6. Each of the joints K1 to K6 is provided with a bearing member 22 composed of a rolling bearing and a seal member 23 as the sliding members 22 and 23, respectively. In FIG. 2, (a) shows a bearing member 22 and (b) shows a seal member 23.

  As shown in FIG. 2A, the bearing member 22 (rolling bearing) smoothes the rotation of the joints K1 to K6, and is provided between the inner ring 22a and the outer ring 22b and between the inner ring 22a and the outer ring 22b. And a plurality of rolling elements 22c (balls or rollers). The bearing member 22 slides as each rolling element 22c rolls and contacts a rolling surface 22d formed on the inner ring 22a and / or the outer ring 22b. As the bearing member 22, for example, a ball bearing (ball bearing), a cross roller bearing, or the like is provided.

  As shown in FIG. 2 (b), the seal member 23 performs sealing in a state in which the seal member 23 is in full contact with the peripheral surface of the counterpart member 25. The entire circumference of the sealing member 23 slides by sliding contact with the counterpart member 25. As the seal member 23, for example, an oil seal for preventing oil (lubricating oil) leakage, a V-ring for preventing intrusion of dust and the like are provided. In FIG. 2B, an oil seal disposed between the shaft portion 25 a and the outer housing 25 b is shown as the seal member 23. The oil seal rotates integrally with the housing 25b, and along with the rotation, the entire inner peripheral surface slides in sliding contact with the outer peripheral surface of the shaft portion 25a.

  Each of the joints K1 to K6 is provided with only the bearing member 22 and the seal member 23 as sliding members, and no sliding members other than the bearing member 22 and the sealing member 23 are provided.

  Next, a deterioration determination system for the sliding members 22 and 23 will be described. FIG. 3 is a diagram illustrating an electrical configuration of the deterioration determination system for the sliding members 22 and 23.

  As shown in FIG. 3, the deterioration determination system includes a robot controller 30 that controls various operations of the robot 10. The controller 30 is mainly composed of a known microcomputer having a CPU and the like, and includes a storage unit 31 and a frequency analysis unit 32. The storage unit 31 stores various programs such as an operation program of the robot 10. The controller 30 performs operation control of the robot 10 based on various programs stored in the storage unit 31.

  The controller 30 is connected to motors 21 provided at the joints K1 to K6. These motors 21 are driven based on control signals from the controller 30. In FIG. 3, only one motor 21 is shown for convenience.

  The controller 30 is connected to a position detector 34 (encoder) that detects the rotational positions of the joints K1 to K6. The position detection unit 34 is provided for each of the joints K1 to K6 (each motor 21), and only one position detection unit 34 is illustrated in FIG. 3 for convenience. The rotational position information of the joints K <b> 1 to K <b> 6 is input to the controller 30 from each position detection unit 34. The controller 30 feedback-controls the driving of each motor 21 based on the input rotational position information.

  Further, the controller 30 rotates the joints K1 to K6 to a predetermined target position by the motor 21 based on the rotational position information of the joints K1 to K6 input from the position detection units 34. A convergence time T until the rotational position converges to the target position is calculated (convergence time acquisition means). In this case, the controller 30 calculates the convergence time T for each of the joints K1 to K6 (each motor 21).

  Specifically, when the controller 30 causes the motor 21 to rotate the joints K1 to K6 from the predetermined rotation start position ha to the target position hb, the rotational positions of the joints K1 to K6 are predetermined with respect to the target position hb. Is calculated as the convergence time T (see FIG. 6). That is, in this case, the rotational positions of the joints K1 to K6 are converged to the target position hb when the rotational positions are converged to the target range.

  The controller 30 is connected to a current detection unit 35 that detects the value of the current flowing through the motor 21. The current detection unit 35 is provided for each motor 21, and only one current detection unit 35 is illustrated in FIG. 3 for convenience. The controller 30 receives the current value of each motor 21 from each current detection unit 35. The controller 30 calculates the load factor of each motor 21 based on the input current value of each motor 21 (load information acquisition means). In this case, the controller 30 calculates the load factor of the motor 21 by, for example, dividing the input current value of the motor 21 by the preset rated current value of the motor 21. Note that the load factor of the motor 21 corresponds to load information related to the driving load of the motor 21.

  Further, the controller 30 detects the vibration generated when the joints K1 to K6 are rotationally driven by the motor 21 as the vibration of the current value based on the current value of each motor 21 input from each current detection unit 35. . The controller 30 performs frequency analysis on the detected vibration in the frequency analysis unit 32.

  The controller 30 is connected to an operation device 40 for performing various operations related to the deterioration determination system. The operation device 40 is configured by a known personal computer (terminal device), and includes an operation unit 41 including a keyboard and a display unit 42 including a display. Note that the operating device 40 may be configured by a teaching pendant instead of the terminal device.

  In the controller 30, as the operation mode of the robot 10, a normal operation mode in which the robot 10 (specifically, the joints K1 to K6) is normally operated and a constant speed operation mode in which the predetermined joints K1 to K6 are rotated at a constant speed. And are set. Switching to these modes is performed based on the operation of the operation unit 41. Specifically, when a mode switching operation is performed by the operation unit 41, a mode signal corresponding to the switching operation is input from the operation unit 41 (operation device 40) to the controller 30, and the controller 30 receives the input mode. The operation mode is switched based on the signal. In this case, the operation unit 41 corresponds to a switching unit.

  Next, the deterioration determination process executed by the controller 30 will be described with reference to FIG. FIG. 4 is a flowchart showing the deterioration determination process. The deterioration determination process is a process of determining whether or not deterioration has occurred in the sliding members 22 and 23 provided in the joints K1 to K6. This process is repeatedly executed at a predetermined cycle when the robot 10 in the assembly line is normally operated (during normal operation). Therefore, this process is executed in a state where the operation mode of the robot 10 is set to the normal operation mode.

  As shown in FIG. 4, first, in step S <b> 11, the load factor W of each motor 21 is calculated based on the detection signal from each current detection unit 35. Further, the convergence time T of each motor 21 is calculated based on the detection signal from each position detector 34.

  In step S12, it is determined for each motor 21 whether or not the load factor W of the motor 21 is larger than a predetermined threshold value Wa. Here, it is conceivable that the sliding resistance of the sliding members 22 and 23 is increased when the sliding members 22 and 23 are deteriorated due to foreign matters mixed in or flaking. In that case, it is considered that the driving load of the motor 21 that rotationally drives the joints K1 to K6 against the sliding resistance increases. Therefore, in this case, it is considered that the load factor of the motor 21 also increases. For example, FIG. 5 shows the change over time of the load factor of the motor 21, but in FIG. 5, the load factor of the motor 21 increases from the time t1, and the sliding members 22, 23 at the time t1. It is thought that the deterioration of has started.

  Therefore, in this step S12, in view of such a point, the above-mentioned determination regarding the load factor W of the motor 21 is performed for each motor 21, so that the sliding members 22 and 23 are respectively associated with the joints K1 to K6. It is determined whether or not deterioration has occurred. Specifically, for each of the joints K1 to K6, it is determined whether any of the plurality of sliding members 22 and 23 provided in the joints K1 to K6 has deteriorated. In this step S12, regarding the joints K1 to K6 for which it is determined that the load factor W of the motor 21 is greater than the threshold value Wa, it is determined that the sliding members 22 and 23 have deteriorated, and the motor 21 For the joints K1 to K6 for which the load factor W is determined to be equal to or less than the threshold value Wa, it is determined that the sliding members 22 and 23 have not deteriorated. The threshold Wa is set individually for each motor 21.

  Here, in the present embodiment, the threshold value Wa is set based on the initial value W0 of the load factor W of the motor 21. Specifically, the threshold value Wa is set to a value larger than the initial value W0 by a predetermined value. Has been. The initial value W0 of the load factor W is based on the operation of the operation unit 41 when the operation of the robot 10 in the assembly line is started (more specifically, when the operation of the robot 10 is stabilized after the operation of the robot 10 is started). It is registered by the initial value registration process performed. In this registration process, the controller 30 calculates the load factor W of each motor 21 based on the current value from each current detector 35, and stores the calculated load factor W of each motor 21 as an initial value W0. 31 (registered). Then, the controller 30 sets the threshold value Wa based on the initial value W0 stored in the storage unit 31.

  In step S13, it is determined for each motor 21 whether or not the convergence time T of the motor 21 has become longer than a predetermined time Ta. Here, when the sliding members 22 and 23 are deteriorated, depending on the deterioration state (deterioration mode) of the sliding members 22 and 23, vibration generated when the joints K1 to K6 are rotated by the motor 21 becomes large. Can be considered. In that case, when the joints K1 to K6 are rotationally driven by the motor 21 to the predetermined target position hb, it is conceivable that the convergence time T until the rotational positions of the joints K1 to K6 converge to the target position hb is increased. For example, in FIG. 6A, when the sliding members 22 and 23 are not deteriorated, in FIG. 6B, the rotational positions of the joints K1 to K6 when the sliding members 22 and 23 are deteriorated. As shown in FIGS. 6 (a) and 6 (b), when the sliding members 22 and 23 are deteriorated, they are generated when the joints K1 to K6 are rotated. The vibration increases and the convergence time T becomes longer.

  Therefore, in this step S13, in view of such a point, the above-described determination regarding the convergence time T of each motor 21 is performed for each motor 21, so that each of the joints K1 to K6 is subjected to the sliding members 22 and 23, respectively. It is determined whether or not deterioration has occurred. Specifically, for each of the joints K1 to K6, it is determined whether any of the plurality of sliding members 22 and 23 provided in the joints K1 to K6 has deteriorated. In this step S13, it is determined that the sliding members 22 and 23 have deteriorated for the joints K1 to K6 for which it is determined that the convergence time T of the motor 21 is longer than the predetermined time Ta (FIG. 6 ( On the other hand, regarding the joints K1 to K6 for which the convergence time T of the motor 21 is determined to be equal to or less than the predetermined time Ta, it is determined that the sliding members 22 and 23 are not deteriorated (FIG. 6A). )reference).

  Here, in the present embodiment, the predetermined time Ta is set based on the initial value T0 of the convergence time T of the motor 21, and specifically, the predetermined time Ta is set to a value larger than the initial value T0 by a predetermined value. Is set. The initial value T0 of the convergence time T is registered by the above-described initial value registration process performed when the operation of the robot 10 in the assembly line is started. In this process, the controller 30 calculates the convergence time T of each motor 21 based on the rotational position information from each position detection unit 34, and stores the calculated convergence time T of each motor 21 as an initial value T0. 31 (registered). Then, the controller 30 sets a predetermined time Ta based on the initial value T0 stored in the storage unit 31.

  In step S14, based on the determination results in step S12 and step S13, it is determined whether or not the sliding members 22 and 23 have deteriorated in any of the joints K1 to K6. If any of the joints K1 to K6 has deteriorated in the sliding members 22 and 23, the process proceeds to step S15. On the other hand, this process is complete | finished when deterioration has not arisen in the sliding members 22 and 23 in any joint K1-K6.

  In step S15, a deterioration warning process for warning that the sliding members 22 and 23 are deteriorated is performed. In this process, by outputting a warning signal to the display unit 42 of the operating device 40, a warning display indicating that the sliding members 22 and 23 have deteriorated is displayed on the display unit 42. For example, a message such as “the sliding member has deteriorated” is displayed on the display unit 42. As a result, the operator of the assembly line can know that the sliding members 22 and 23 have deteriorated, and can take quick measures against the deterioration of the sliding members 22 and 23. Therefore, it is possible to avoid the inconvenience that the degradation of the sliding members 22 and 23 progresses without knowing and the operation of the robot 10 stops. In this case, the display unit 42 corresponds to warning means.

  The deterioration warning of the sliding members 22 and 23 is not necessarily performed using the display unit 42. For example, a sound output unit such as a speaker that outputs sound may be provided in the operation device 40, and the deterioration warning may be performed by sound output from the sound output unit. Further, a light emitting unit that emits light may be provided in the operating device 40, and a deterioration warning may be given by light from the light emitting unit.

  In step S16, a target joint specifying process is performed for specifying which of the joints K1 to K6 has deteriorated in the sliding members 22 and 23. In this process, the joints K1 to K6 in which the sliding members 22 and 23 are deteriorated are specified, and the specified joints K1 to K6 (hereinafter also referred to as the target joint Ka) are stored in the storage unit 31. In this process, the identified joints K1 to K6 (target joint Ka) are further displayed on the display unit 42 of the operating device 40. As a result, the operator of the assembly line can know which joints K1 to K6 have deteriorated in the sliding members 22 and 23, and therefore can easily cope with the deterioration of the sliding members 22 and 23. In this case, the display unit 42 corresponds to a notification unit. After this step S16, this process is terminated.

  Next, the deterioration member specifying process executed by the controller 30 when it is determined by the above-described deterioration determination process that the slide members 22 and 23 are deteriorated will be described with reference to FIG. FIG. 7 is a flowchart showing the deteriorated member specifying process. The deteriorated member specifying process is a process of specifying which one of the bearing member 22 and the seal member 23 is the sliding members 22 and 23 determined to be deteriorated by the above-described deterioration determining process. In this process, the operation mode is switched from the normal operation mode to the constant speed operation mode by the operation of the operation unit 41, and the start button provided in the operation unit 41 is operated under the switched constant speed operation mode. It is started as a trigger.

  As shown in FIG. 7, first, in step S21, constant velocity rotation processing is performed on the joints K1 to K6 (that is, the target joint Ka) determined to have deteriorated in the sliding members 22 and 23 by the deterioration determination processing. Specifically, the target joint Ka stored in the storage unit 31 in step S16 of the deterioration determination process is read from the storage unit 31, and constant speed rotation processing is performed on the target joint Ka.

  In this constant speed rotation process, a constant speed drive signal is output to the motor 21 provided in the target joint Ka, so that the target joint Ka is rotationally driven by the motor 21 at a constant speed. More specifically, among the motors 21 provided in the joints K1 to K6, the drive signal (constant speed drive signal) is output only to the motor 21 provided in the target joint Ka, and the others No drive signal is output to the motor 21. Accordingly, only the target joint Ka among the joints K1 to K6 is rotationally driven by the motor 21 at a constant speed, and the rotational driving by the motor 21 is stopped for the other joints K1 to K6.

  In the following description, it is assumed that a plurality of (specifically, two) bearing members 22 are provided in the target joint Ka. In the following, in order to distinguish these bearing members 22, for the sake of convenience, each bearing member 22 is also referred to as a first bearing member 22A and a second bearing member 22B, respectively.

  In step S22, vibration generated when the target joint Ka rotates at a constant speed is detected based on a detection signal from the current detection unit 35 provided in the target joint Ka.

  By the way, in the bearing member 22, when the rolling surface 22d is damaged due to flaking, foreign matter mixing, etc., it is considered that vibration is generated every time the rolling element 22c passes through the damaged portion. Therefore, when the bearing member 22 is deteriorated (damaged), it is considered that a large vibration is periodically generated when the target joint Ka is rotated at a constant speed as described above. On the other hand, since the entire circumference of the seal member 23 slides in a sliding contact with the mating member 25, when the seal member 23 is damaged, the damaged portion is always attached to the mating member 25. It will come into contact. For this reason, when the seal member 23 is deteriorated (scratched), it is considered that no significant vibration is periodically generated when the target joint Ka rotates at a constant speed.

  Therefore, in the following steps (steps S23 to S26), paying attention to the fact that the mode of vibration differs between the case where the bearing member 22 is deteriorated and the case where the seal member 23 is deteriorated as described above, Processing to specify which of the bearing member 22 and the seal member 23 is the moving member is performed.

  First, in step S23, the frequency analysis unit 32 performs frequency analysis on the vibration during constant speed rotation detected in step S22. By this frequency analysis, a frequency spectrum of the vibration is obtained. FIGS. 8A to 8D show the frequency spectrum. 8A to 8D, two specific frequencies f1 and f2 are shown on the horizontal axis. These specific frequencies f1 and f2 are determined corresponding to the respective bearing members 22A and 22B provided in the target joint Ka. Specifically, the specific frequencies f1 and f2 are specific frequencies of the bearing member 22 determined based on various parameters related to the bearing member 22, such as the diameters of the inner ring 22a and the outer ring 22b of the bearing member 22 and the diameter and number of the rolling elements 22c. It has become. Here, the specific frequency f1 corresponds to the first bearing member 22A, and the specific frequency f2 corresponds to the second bearing member 22B. The correspondence between the specific frequencies f1 and f2 and the bearing members 22A and 22B is stored in the storage unit 31 in advance.

  In step S24, it is determined whether or not there is a frequency peak in which the amplitudes V1 and V2 at the specific frequencies f1 and f2 are larger than the predetermined thresholds Va and Vb in the frequency spectrum of the vibration (corresponding to determination processing). Specifically, in this step, a frequency peak in which the amplitude V1 at the specific frequency f1 is larger than the threshold Va (hereinafter referred to as a first frequency peak) and an amplitude V2 at the specific frequency f2 are included in the vibration frequency spectrum. It is determined whether or not at least one of frequency peaks (hereinafter referred to as second frequency peaks) that are larger than Vb exists.

  In the present embodiment, the thresholds Va and Vb are determined based on the initial values V1 (0) and V2 (0) of the amplitudes V1 and V2 at the specific frequencies f1 and f2. Specifically, the thresholds Va and Vb are the initial values. The values are set larger than the values V1 (0) and V2 (0) by a predetermined value. The initial values V1 (0) and V2 (0) of the amplitudes V1 and V2 are initial values that are determined based on the operation of the operation unit 41 when the robot 10 is installed on the assembly line (specifically, before the operation of the robot 10 starts). Registered by the registration process. In this registration process, the controller 30 rotates the joints K1 to K6 at a constant speed by the motor 21, detects vibrations generated during the constant speed rotation based on the detection signal from the current detection unit 35, and detects the detected vibrations. The frequency analysis unit 32 performs frequency analysis. Then, the amplitudes V1 and V2 at the specific frequencies f1 and f2 are determined based on the frequency spectrum of the vibration obtained by the frequency analysis, and the determined amplitudes V1 and V2 are set to initial values V1 (0) and V2 (0, respectively. ) Is stored (registered) in the storage unit 31. Then, the controller 30 sets the thresholds Va and Vb based on the initial values V1 (0) and V2 (0) stored in the storage unit 31.

  In step S24, when neither the first frequency peak nor the second frequency peak is present in the frequency spectrum of vibration (in the case of FIG. 8A), the target joint Ka is periodically rotated at a constant speed. Since it can be considered that no large vibration has occurred, in this case, the sliding member having deteriorated is identified as the seal member 23 (step S26). On the other hand, when at least one of the first frequency peak and the second frequency peak is present in the frequency spectrum of vibration, it can be considered that a large vibration is periodically generated during constant speed rotation of the target joint Ka. Therefore, in this case, the sliding member that has deteriorated is identified as the bearing member 22 (step S25). After step S25, the process proceeds to step S27.

  In steps S27 to S31, a bearing member specifying process for specifying which of the bearing members 22A and 22B is the bearing member 22 in which the deterioration has occurred is performed. In this process, first, in step S27, it is determined whether a frequency peak exists in one or both of the specific frequencies f1 and f2. When the frequency peak exists in both of the specific frequencies f1 and f2 (in the case of FIG. 8D), the process proceeds to step S29, and the bearing members 22A and 22B corresponding to the specific frequencies f1 and f2 are set. Each is read from the storage unit 31. Then, the read bearing members 22A and 22B are specified as deteriorated sliding members (bearing members 22).

  In step S27, when the frequency peak exists only in one of the specific frequencies f1 and f2, the process proceeds to step S28, and in which specific frequency of the specific frequencies f1 and f2 the frequency peak exists. Determine. When the frequency peak is present at the specific frequency f1 (in the case of FIG. 8B), the process proceeds to step S30, and the first bearing member 22A corresponding to the specific frequency f1 is read from the storage unit 31. Then, the read first bearing member 22A is specified as a deteriorated sliding member. On the other hand, when the frequency peak exists at the specific frequency f2 (in the case of FIG. 8C), the process proceeds to step S31, and the second bearing member 22B corresponding to the specific frequency f2 is read from the storage unit 31. Then, the read second bearing member 22B is specified as a deteriorated sliding member. In addition, said step S27 and step S28 are equivalent to a peak determination process.

  In step S32, the deteriorated sliding member specified as the sliding member deteriorated in any of steps S29 to S31 is displayed on the display unit 42 of the operating device 40. For example, a message such as “the seal member has deteriorated” or “the first bearing member has deteriorated” is displayed on the display unit 42. Thereby, it can be known whether the deteriorated sliding members 22 and 23 are the bearing member 22 or the seal member 23. Further, when the bearing member 22 is deteriorated, it is possible to know which of the deteriorated bearing members 22 is.

  As mentioned above, according to the structure of this embodiment explained in full detail, the following outstanding effects are acquired.

  When it is determined that the sliding members 22 and 23 are deteriorated, the vibration generated when the target joint Ka is rotationally driven by the motor 21 is detected, and the detected vibration is subjected to frequency analysis. It was determined whether or not there was a frequency peak in the frequency spectrum of vibration obtained by frequency analysis. When a frequency peak exists in the frequency spectrum, the deteriorated sliding member is specified as the bearing member 22, and when the frequency peak does not exist in the frequency spectrum, the deteriorated sliding member is specified as the seal member 23. As a result, when the sliding members 22 and 23 are deteriorated, the sliding member 22 is specified as one of the bearing member 22 and the seal member 23. Therefore, when the sliding member is deteriorated. The deteriorated sliding member can be identified relatively easily.

  When it is determined that the sliding members 22 and 23 are deteriorated, the target joint Ka is rotated at a constant speed by the motor 21 by switching the operation mode of the robot 10 from the normal operation mode to the constant speed operation mode. I let you. And the vibration which generate | occur | produces in the case of the constant speed rotation is detected, and frequency analysis is performed about the vibration in the case of the constant speed rotation. Here, when the bearing member 22 is deteriorated (damaged), it is considered that a large vibration is generated at a constant cycle when the target joint Ka is rotated at a constant speed. For this reason, it is considered that frequency peaks at the specific frequencies f1 and f2 are likely to appear remarkably in the frequency spectrum of vibration (during constant speed rotation) obtained by frequency analysis. Therefore, according to such a configuration, in the above-described configuration in which the deteriorated sliding member is specified based on the presence or absence of the frequency peak, the specification can be suitably performed.

  Specifically, in the constant speed operation mode, only the target joint Ka among the joints K1 to K6 is rotationally driven by the motor 21 at a constant speed, and the rotational driving by the motor 21 is stopped for the other joints. In this case, in an articulated robot having a plurality of joints K1 to K6, vibrations generated with the rotation of the target joint Ka can be suitably detected. Therefore, based on the detected vibrations (specifically, a frequency spectrum). Thus, it is possible to suitably perform the process for identifying the deteriorated sliding member.

  When it is determined that a frequency peak exists in the frequency spectrum of the vibration, it is determined which specific frequency f1, f2 the frequency peak exists, and the bearing member 22 corresponding to the determined specific frequency f1, f2. Is specified as a deteriorated sliding member. In this case, since the deteriorated sliding member is identified from among the bearing members 22A and 22B, the deteriorated sliding member can be identified more easily.

  The load factor W of the motor 21 and the convergence time T of the motor 21 are acquired, respectively, and whether or not the sliding members 22 and 23 have deteriorated is determined based on the acquired load factor W and convergence time T of the motor 21. To do. Specifically, when the load factor W of the motor 21 is larger than a predetermined threshold value Wa, it is determined that the sliding members 22 and 23 are deteriorated. Further, when the convergence time T of the motor 21 is longer than the predetermined time Ta, it is determined that the sliding members 22 and 23 are deteriorated. In this case, since the deterioration determination of the sliding members 22 and 23 is performed based on the two motor drive characteristics, it is possible to improve the accuracy of the deterioration determination.

  Further, since the load factor W and the convergence time T of the motor 21 are acquired and the deterioration of the sliding members 22 and 23 is determined during normal operation of the robot 10 in the assembly line (when the normal operation mode is set), There is no need to stop the line when making a decision. Further, since the deterioration determination is performed during normal operation of the robot 10, it is possible to immediately know that the deterioration has occurred when the sliding members 22 and 23 are deteriorated during the operation of the robot 10. Therefore, it is possible to take a quick response to the deterioration of the sliding members 22 and 23.

  The present invention is not limited to the above embodiment, and may be implemented as follows, for example.

  (1) In the above embodiment, the deterioration determination of the sliding members 22 and 23 is performed based on the load factor W of the motor 21 and the convergence time T of the motor 21, but the load factor W and convergence time T of the motor 21 are determined. The deterioration determination may be performed based on only one of them. Moreover, it replaces with the load factor W of the motor 21, and the drive load (torque) of the motor 21 may be acquired and deterioration determination may be performed based on the drive load (equivalent to load information).

  (2) In the above embodiment, the operation mode of the robot 10 is set to the constant speed operation mode, and the vibration generated when the target joint Ka is rotated at the constant speed by the motor 21 is detected and the frequency analysis is performed. May be changed. For example, the frequency analysis may be performed by detecting vibrations generated when the target joint Ka is rotated during normal operation of the robot 10 (during normal operation mode). Even in this case, if the rotation is at a constant speed or a rotation close thereto, it is possible to identify a deteriorated sliding member based on the frequency spectrum of vibration generated during the rotation.

  (3) In the above-described embodiment, vibration generated when the joints K1 to K6 are rotationally driven by the motor 21 is detected based on the current value of the motor 21 detected by the current detection unit 35. However, such vibration is detected. The method to do is not necessarily limited to this. For example, the torque value of the motor 21 is calculated (estimated) based on the current value of the motor 21 detected by the current detection unit 35, and the above vibration is detected (as the vibration of the torque value) based on the calculated torque value. You may make it do. In this case, frequency analysis is performed on the vibration data of the detected torque value.

  The motor 21 performs feedback control (speed feedback control) based on the rotational positions of the joints K1 to K6 detected by the position detector 34 (encoder). The target torque of the motor 21 may be calculated based on the above, and the above vibration may be detected based on the calculated target torque.

  Furthermore, vibration sensors that detect vibrations may be provided in the joints K1 to K6, and vibrations generated when the joints K1 to K6 are rotationally driven by the vibration sensors may be detected.

  (4) In the above embodiment, the bearing member specifying process (steps S27 to S31) has been described by taking the case where the two joint members 22 are provided in the target joint Ka as an example, but three or more bearings are provided in the target joint Ka. Even when the member 22 is provided, the specific frequency corresponding to each bearing member 22 is different, so this processing can be applied.

  (5) In the above embodiment, the deterioration determination system of the present invention is applied to a six-axis robot having six joints K1 to K6. However, the present invention is applied to other articulated robots such as a five-axis robot and a four-axis robot. You may apply. Further, the present invention may be applied to a single-axis robot having only one joint.

  DESCRIPTION OF SYMBOLS 10 ... Robot, 21 ... Motor, 22 ... Bearing member, 23 ... Seal member, 30 ... Controller, 32 ... Frequency analysis part, 41 ... Operation part, 42 ... Display part, K1-K6 ... Joint.

Claims (7)

A motor that rotationally drives the joint;
A ring surrounding the rotation axis of the joint, and a plurality of sliding members that slide with the rotation of the joint;
The plurality of sliding members include a bearing member composed of a rolling bearing that slides when the rolling element is in rolling contact with the rolling surface, and a seal member that slides when the entire circumference is in sliding contact with the mating member. Applies to robots that contain
Load information acquisition means for acquiring load information related to a driving load of the motor that rotationally drives the joint at a predetermined period;
Each time the load information of the motor is acquired by the load information acquisition means, it is determined whether any of the plurality of sliding members has deteriorated based on the acquired load information of the motor. Deterioration determination means;
Vibration detection means for detecting vibrations generated when the joint is rotated by the motor when it is determined by the deterioration determination means that any of the sliding members has deteriorated;
Frequency analysis means for performing frequency analysis on the vibration detected by the vibration detection means;
Determining means for determining whether or not there is a frequency peak in which the amplitude at a specific frequency determined corresponding to the bearing member is larger than a predetermined value in the frequency spectrum of the vibration obtained by the frequency analysis;
When it is determined that the frequency peak exists in the frequency spectrum of the vibration, the sliding member that has deteriorated is identified as the bearing member, and it is determined that the frequency peak does not exist in the frequency spectrum of the vibration. A specific means for identifying the sliding member that has deteriorated as the seal member in the case of deterioration,
A deterioration determination system for a sliding member, comprising: When the deterioration determining means determines that the sliding member has deteriorated, the operation mode of the robot is switched from the normal operation mode to the constant speed operation mode in which the joint is rotated at a constant speed by the motor. Switching means for
The vibration detecting means detects vibration generated when the joint rotates at a constant speed under the constant speed operation mode,
The sliding member deterioration determination system according to claim 1, wherein the frequency analysis unit performs frequency analysis on the detected vibration at the time of constant speed rotation. Applied to a multi-joint robot having a plurality of the joints;
Each of the joints is provided with the motor and the plurality of sliding members,
The load information acquisition means acquires load information of each motor,
The deterioration determining means determines whether or not the sliding member has deteriorated for each joint based on the acquired load information of each motor.
In the constant speed operation mode, among the joints, only the joints determined by the deterioration determining means to be deteriorated in the sliding member are rotated at a constant speed by the motor, and the other joints are determined. 3. The sliding member deterioration determination system according to claim 2, wherein rotation driving by the motor is stopped.   The sliding device according to any one of claims 1 to 3, further comprising a warning unit that warns that the sliding member has been deteriorated by the deterioration determining unit. Deterioration judgment system for moving members. Applied to a multi-joint robot having a plurality of the joints;
Each of the joints is provided with the motor and the plurality of sliding members,
The load information acquisition means acquires load information of each motor,
The deterioration determining means determines whether or not the sliding member has deteriorated for each joint based on the acquired load information of each motor.
2. The information processing apparatus according to claim 1, further comprising a notification unit configured to notify the joint of the sliding member when the deterioration determining unit determines that the sliding member has deteriorated in any of the joints. The deterioration determination system for a sliding member according to any one of claims 1 to 4. When driving rotating the joint by the previous SL motor to a predetermined target position, comprising a convergence time acquisition hand stage the rotational position of the joint to acquire the convergence time to converge to the target position at a predetermined cycle,
Before SL deterioration determining unit obtains the load information of the motor by the load information acquisition unit, and every time to get the convergence time of the motor by the convergence time acquisition means, the load information and the convergence of the motor with those acquired based on the inter-time deterioration determination system of the sliding member according to any one of claims 1 to 5, characterized in that to determine whether the degradation in the sliding member has occurred. A plurality of the bearing members are provided in the joint,
The specific frequency is determined corresponding to each of the bearing members,
When it is determined by the determination means that the frequency peak exists in the frequency spectrum of the vibration, the peak determination means for determining which specific frequency the frequency peak exists in,
2. The specifying unit specifies the bearing member corresponding to the specific frequency determined by the peak determining unit as having the frequency peak as the sliding member having deteriorated. The sliding member deterioration determination system according to any one of claims 1 to 6.

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