Brake diagnostic device and brake diagnostic method

Abstract

To provide a brake diagnostic device and a brake diagnostic method which can diagnose a brake with a simple structure, and prevent a motor from continuing rotating even if there is an abnormality in the brake at the time of diagnosis.SOLUTION: A brake diagnostic device comprises: a motor control unit 8; a brake control unit 9; a position command output unit 1 which outputs a normal position command value to the motor control unit 8 in a normal operation mode; a diagnostic command output unit 4 which outputs a diagnostic position command value to the motor control unit 8 in a brake diagnostic mode, and outputs a recovery position command value to the motor control unit 8 in a recovery mode; a position acquisition unit E; a diagnosis unit 3 which diagnoses presence / absence of abnormality of an electromagnetic brake B; and a position deviation calculation unit 2 which calculates position deviation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a brake diagnostic device and a brake diagnostic method. [Background technology]

[0002] 2. Description of the Related Art Some brake-equipped motors used in industrial robots and machine tools have a function for self-diagnosing whether the brake is functioning normally.

[0003] For example, in the motor control device with self-diagnosis function disclosed in Patent Document 1, torque is applied by torque control while the brake is applied, and whether the brake is functioning normally is diagnosed based on the amount of positional deviation of the motor before and after the torque application.

[0004] For example, in the motor control device with self-diagnosis function in Patent Document 2, a position command is output while the brake is applied, and whether the brake is functioning normally is diagnosed based on the amount of movement of the motor before and after the output of the position command. Furthermore, after the diagnosis is completed, the position of the motor is returned to the diagnosis start position based on the amount of movement of the motor during the diagnosis. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-240180 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-101643 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the motor control device with self-diagnosis function disclosed in Patent Document 1 uses torque control, so there is a risk that the motor will continue to rotate if the holding torque of the electromagnetic brake decreases. Also, the motor control device with self-diagnosis function disclosed in Patent Document 2 needs to calculate the motor movement amount to return the motor position to the diagnosis start position after the diagnosis is completed.

[0007] Therefore, an object of the present invention is to provide a brake diagnostic device and a brake diagnostic method that can diagnose a brake with a simple configuration and that will not cause the motor to continue rotating even if there is an abnormality in the brake. [Means for solving the problem]

[0008] A brake diagnosis device according to one aspect of this embodiment includes: A brake diagnostic device for diagnosing a brake of an electromagnetic brake-equipped motor, comprising: a motor control unit that controls the motor; a brake control unit that controls an electromagnetic brake; a position command output unit that outputs a normal position command value to the motor control unit in a normal operation mode; a diagnostic command output unit that outputs a diagnostic position command value to the motor control unit in a brake diagnosis mode and outputs a return position command value to the motor control unit in a return mode for returning the motor from a position after the brake diagnosis to a position before the brake diagnosis; a position acquisition unit that acquires the position of the motor; a diagnosis unit that diagnoses whether or not there is an abnormality in the electromagnetic brake; a position deviation calculation unit that calculates a position deviation that is an accumulated value of a difference between a normal position command value output by the command output unit and the position of the motor acquired by the position acquisition unit, In the brake diagnosis mode, the brake control unit operates the electromagnetic brake, and the motor control unit operates the motor based on a command value obtained by adding a predetermined diagnostic position command value to the position deviation, and when the position deviation is equal to or greater than a threshold value, the diagnosis unit determines that the electromagnetic brake is abnormal.

[0009] A brake diagnosis method according to one aspect of this embodiment includes: A brake diagnosis method for diagnosing a brake abnormality in an electromagnetic brake-equipped motor, comprising: a position deviation calculation step of calculating a position deviation which is an accumulated value of the difference between the normal position command value and the motor position; a diagnostic position control step of operating the electromagnetic brake in a diagnostic mode and operating the motor based on a command value obtained by adding a diagnostic position command value, which is a predetermined value, to the position deviation; a diagnosis step of determining that the electromagnetic brake is abnormal when the position deviation is equal to or greater than a threshold value; Equipped with. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a brake diagnostic device and a brake diagnostic method that are capable of diagnosing a brake with a simple configuration and that prevent the motor from continuing to rotate even if an abnormality is found in the brake during diagnosis. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram of a motor control device and an electromagnetic brake motor according to an embodiment of the present invention. [Figure 2] 4 is a flowchart illustrating an example of brake diagnosis. [Figure 3] 10 is a timing chart showing an example of operation in a brake diagnosis mode when the brake is normal. [Figure 4] 10 is a timing chart showing an example of operation in a brake diagnosis mode when a brake abnormality occurs. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the present embodiment will be described with reference to the drawings. For the sake of convenience, the description of the components having the same reference numerals as those already described in the description of the embodiment will be omitted. <Configuration of an electromagnetic brake motor>

[0013] FIG. 1 is a block diagram of a motor control device and an electromagnetic brake motor according to this embodiment. As shown in FIG. 1, the motor control device 100 is connected to a motor M and an electromagnetic brake B and is configured to perform feedback control of the drive of the motor M and the operation of the electromagnetic brake B. The motor control device 100 also includes a position command output unit 1, a position deviation calculation unit 2, a diagnosis unit 3, a diagnostic command output unit 4, a position control unit 5, a speed conversion unit 6, a speed control unit 7, a motor control unit 8, and a brake control unit 9. The motor control device 100 also includes at least three operating modes: a normal operation mode in which the motor M is operated based on a position command; a brake diagnosis mode in which the electromagnetic brake B is diagnosed for abnormalities; and a return mode in which the motor M is returned from a position after the brake diagnosis to a position before the brake diagnosis. The electromagnetic brake motor includes the motor M, the electromagnetic brake B, and an encoder E. In the example shown in FIG. 1, the motor M is a servo motor. The electromagnetic brake B is an excitation-activated brake or a non-excitation-activated brake. The encoder E detects the position of the motor M.

[0014] A position command output unit 1 outputs a normal state position command value Pr, which is a position command during normal operation, based on a target position specified by the user. A position deviation calculation unit 2 receives an input of a difference Pd between the normal state position command value Pr output from the position command output unit 1 and a detected position P of the motor M acquired by an encoder. The position deviation calculation unit 2 also calculates and outputs a position deviation Pda, which is an accumulated value of the difference Pd. A diagnosis unit 3 receives an input of the position deviation Pda output from the position deviation calculation unit 2, and determines that the electromagnetic brake B is abnormal when the position deviation Pda is equal to or greater than a predetermined threshold value Th in a brake diagnosis mode. A detailed determination method will be described later.

[0015] The diagnostic command output unit 4 outputs a diagnostic position command value Prd for driving the motor M for diagnosis in the brake diagnosis mode, and outputs a return position command value Prr for returning the motor M from the position after the brake diagnosis to the position before the brake diagnosis in the return mode. The diagnostic position command value Prd or the return position command value Prr output from the diagnostic command output unit 4 is added to the position deviation Pda output from the position deviation calculation unit 2, and the result is input to the position control unit 5. The position control unit 5 generates and outputs a speed command Vr based on the input position command. The speed conversion unit 6 calculates and outputs a detected speed V, which is the rotational speed of the motor M, for example, by a differential operation based on a change in the detected position P of the motor M acquired by the encoder E. The detected speed V output from the speed conversion unit 6 is subtracted from the speed command Vr output from the position control unit 5, and the result is input to the speed control unit 7. The speed control unit 7 generates and outputs a torque command Tr based on the input speed command. The motor control unit 8 controls the torque of the motor M based on the torque command Tr output from the speed control unit 7. The brake control unit 9 controls the brake B by generating a brake signal and outputting it to the brake B.

[0016] The motor control device 100 shown in FIG. 1 includes a memory and a processor. The memory is configured to store computer-readable instructions (programs). The memory may include, for example, a read-only memory (ROM) storing various programs and a random access memory (RAM) storing various programs executed by the processor. The processor may include, for example, at least one of a central processing unit (CPU), a microprocessing unit (MPU), and a graphics processing unit (GPU). The processor may be configured to load a specified program from various programs stored in the storage device or ROM onto the RAM and execute various processes in cooperation with the RAM. The storage device may be, for example, a hard disk drive (HDD), a solid state drive (SSD), a flash memory, or other storage device configured to store programs and various data. <Brake diagnosis operation flowchart>

[0017] FIG. 2 is a flowchart showing an example of brake diagnosis. When the motor control device 100 transitions to brake diagnosis mode (S101), the brake control unit 9 activates the electromagnetic brake B (S102). Next, the diagnostic command output unit 4 outputs a predetermined value, a diagnostic position command value Prd. The output diagnostic position command Prd is added to the position deviation Pda to generate a position command (S103). The generated position command is input to the position control unit 5, which converts the position command into a speed command Vr and outputs it. A speed command is generated by subtracting the detected speed V output from the speed conversion unit 6 from the output speed command Vr (S104). The generated speed command is input to the speed control unit 7, which generates and outputs a torque command Tr based on the speed command (S105). The motor control unit 8 limits the input torque command Tr to a value equivalent to the holding torque when the electromagnetic brake B is normal, and drives and controls the motor M (S106). Here, if the holding torque of electromagnetic brake B is normal and approximately the same as the limit value of torque command Tr, motor M hardly rotates, and therefore position deviation Pda hardly increases. On the other hand, if the holding torque of electromagnetic brake B is smaller than the limit value of torque command Tr due to a brake abnormality, motor M rotates, and position deviation Pda increases. In this case, motor M stops rotating when the electromagnetic brake reaches the diagnostic position command value Prd.

[0018] The diagnostic unit 3 monitors the position deviation Pda in the brake diagnostic mode, and if the position deviation Pda is less than a predetermined threshold value Th (No in S107), it determines that the electromagnetic brake B is normal (S111), and if the position deviation Pda is equal to or greater than the threshold value Th (Yes in S107), it determines that the electromagnetic brake B is abnormal (S108).

[0019] If it is determined that electromagnetic brake B is abnormal (S108), diagnostic command output unit 4 stops outputting diagnostic position command value Prd (S109), and motor control device 100 outputs an alert indicating an abnormality in electromagnetic brake B (S110). The alert can be output, for example, by displaying the alert on a user screen (not shown).

[0020] If it is determined that the electromagnetic brake B is normal (S111), the motor control device 100 transitions to a return mode (S112). Next, the diagnostic command output unit 4 outputs a predetermined return position command value Prr. The return position command value Prr is a fixed value, e.g., 0. The output return position command value Prr is added to the position deviation Pda to generate a position command (S113). The generated position command is input to the position control unit 5, which converts the position command into a speed command Vr and outputs it. A speed command is generated by subtracting the detected speed V output from the speed conversion unit 6 from the output speed command Vr (S114). The generated speed command is input to the speed control unit 7, which generates and outputs a torque command Tr based on the speed command (S115). The motor control unit 8 drives the motor M based on the input torque command Tr to return the motor M from the position after the brake diagnosis to the position before the brake diagnosis (S116).

[0021] In this way, because the configuration is such that the presence or absence of an abnormality in electromagnetic brake B is diagnosed by position control, even if the holding torque of electromagnetic brake B is reduced, rotation of motor M stops when electromagnetic brake B reaches the position command value. Therefore, brake B can be diagnosed without motor M continuing to rotate. Furthermore, by setting return position command value Prr to a fixed value (for example, 0), motor M can be returned to its initial position before brake diagnosis regardless of the position of motor M after brake diagnosis. Therefore, brake diagnosis can be performed with a simple configuration. <Brake diagnosis operation when the brakes are normal>

[0022] FIG. 3 is a timing chart showing an example of operation in the brake diagnosis mode when the brake is normal. First, electromagnetic brake B is activated by the brake control unit 9. Next, at time t0, the servo is turned on to put motor M into a state where it can be driven. Next, at time t1, the torque limit is set to a value equivalent to the holding torque of electromagnetic brake B, and the diagnostic position command value Prd is output. The torque command Tr generated as a result is limited by the torque control unit to a torque equivalent to the holding torque of electromagnetic brake B, and motor M is placed in a state where a drive torque equivalent to the holding torque of electromagnetic brake B is applied. In the example shown in FIG. 3, the position of the motor M moves by a distance M1 from the diagnosis start position due to mounting play inside the electromagnetic brake B, and the position deviation Pda increases from 0 to P1. Because the electromagnetic brake B is normal, the position of the motor M does not change any further even when drive torque is applied, and the position deviation Pda maintains the P1 state. After a predetermined time t has elapsed since the start of output of the diagnostic position command value Prd (time t2), the position deviation Pda is less than the predetermined threshold value Pth, so the diagnostic unit 3 determines that the electromagnetic brake B is normal. Therefore, no alert signal indicating an abnormality in the electromagnetic brake is output. The diagnostic command output unit then outputs a return position command value Prr to return the motor position to the position before the start of the diagnosis, and then turns off the servo. Note that the torque limit may be disabled at the time when the predetermined time t has elapsed since the start of output of the diagnostic position command value Prd (time t2). <Brake diagnosis operation when brake abnormality occurs>

[0023] FIG. 4 is a timing chart showing an example of the operation of the brake diagnosis mode when a brake abnormality occurs. As in FIG. 3, at time t1, the torque limit is set to a value corresponding to the holding torque of electromagnetic brake B, and the diagnostic position command value Prd is output. The torque command Tr thus generated is limited by the torque control unit to a torque corresponding to the holding torque of electromagnetic brake B, and a drive torque corresponding to the holding torque of electromagnetic brake B is applied to motor M. In the example shown in FIG. 4, due to mounting backlash within electromagnetic brake B, the position of motor M moves by a movement amount m1 from the diagnosis start position, and the position deviation Pda increases from 0 to P1. Because electromagnetic brake B is abnormal, the holding torque is smaller than the drive torque, and motor M continues to move. The position of motor M moves by a movement amount M2 from the diagnosis start position (the sum of the movement amount m1 due to mounting backlash within electromagnetic brake B and the movement amount m2 due to the brake abnormality). At time t2′, the position deviation Pda reaches a predetermined threshold value Pth. Because the position deviation Pda exceeds the predetermined threshold value Pth at time t2′, the diagnostic unit 3 determines that electromagnetic brake B is abnormal. Therefore, an alert signal is output indicating that there is an abnormality in the electromagnetic brake. Also, at time t2', the servo is turned off and the torque limit is set to invalid.

[0024] As described above, the brake diagnosis device and brake diagnosis method according to the embodiment of the present invention are configured to diagnose the presence or absence of an abnormality in the electromagnetic brake through position control. Therefore, even if the holding torque of the electromagnetic brake is reduced, the rotation of the motor stops when the electromagnetic brake reaches the position command value. Therefore, the brake can be diagnosed without the motor continuing to rotate. Furthermore, by setting the return position command value to a fixed value (e.g., 0), the motor M can be returned to its initial position before the brake diagnosis, regardless of the position of the motor M after the brake diagnosis. Therefore, the brake diagnosis can be performed with a simple configuration.

[0025] Although the embodiments of the present invention have been described above, it goes without saying that the technical scope of the present invention should not be construed as being limited by the description of the present embodiments. The present embodiments are merely examples, and it will be understood by those skilled in the art that various modifications of the embodiments are possible within the scope of the invention described in the claims. The technical scope of the present invention should be determined based on the scope of the invention described in the claims and its equivalents. [Explanation of symbols]

[0026] 1: Position command output section 2: Position deviation calculation section 3: Diagnostic department 4: Diagnostic command output section 5: Position control section 6: Speed ​​conversion section 7: Speed ​​control section 8: Motor control unit 9: Brake control unit 100: Motor control device B: Electromagnetic brake M: Motor E: Encoder

Claims

1. A brake diagnostic device for diagnosing a brake of an electromagnetic brake-equipped motor, comprising: A motor control unit that controls the motor; A brake control unit that controls an electromagnetic brake; a position command output unit that outputs a normal state position command value to the motor control unit in a normal operation mode; a diagnosis command output unit that outputs a diagnosis position command value to the motor control unit in a brake diagnosis mode and outputs a return position command value to the motor control unit in a return mode for returning the motor from a position after the brake diagnosis to a position before the brake diagnosis; a position acquisition unit for acquiring a position of the motor; a diagnosis unit that diagnoses whether or not there is an abnormality in the electromagnetic brake; a position deviation calculation unit that calculates a position deviation that is an accumulated value of a difference between a normal position command value output by the command output unit and a position of the motor acquired by the position acquisition unit, In the brake diagnosis mode, the brake control unit operates the electromagnetic brake, and the motor control unit operates the motor based on a command value obtained by adding a diagnostic position command value, which is a predetermined value, to the position deviation, and when the position deviation is equal to or greater than a threshold value, the diagnosis unit determines that the electromagnetic brake is abnormal. Brake diagnostic device.

2. 2. The brake diagnosis device according to claim 1, wherein in the return mode, the motor control unit causes the motor to return from a position after the brake diagnosis to a position before the brake diagnosis based on a command value obtained by adding a return position command value that is a predetermined value to the position deviation.

3. 2. The brake diagnostic device according to claim 1, wherein the return position command value is zero.

4. 2. The brake diagnosis device according to claim 1, wherein, in the brake diagnosis mode, when the position deviation is equal to or greater than a threshold value, the diagnostic command output unit stops outputting the diagnostic position command value, and the diagnosis unit outputs an alert indicating that the electromagnetic brake is abnormal.

5. A brake diagnosis method for diagnosing a brake abnormality in an electromagnetic brake motor, comprising: a position deviation calculation step of calculating a position deviation which is an accumulated value of the difference between a normal position command value and a motor position; a diagnostic position control step of operating an electromagnetic brake in a diagnostic mode and operating the motor based on a command value obtained by adding a diagnostic position command value, which is a predetermined value, to the position deviation; a diagnosis step of determining that the electromagnetic brake is abnormal when the position deviation is equal to or greater than a threshold value; A brake diagnostic method comprising:

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