WO2023021575A1

WO2023021575A1 - Servo motor brake state judgment device and brake state judgment unit

Info

Publication number: WO2023021575A1
Application number: PCT/JP2021/030025
Authority: WO
Inventors: 慎司奥村; 直人高野
Original assignee: 三菱電機株式会社
Priority date: 2021-08-17
Filing date: 2021-08-17
Publication date: 2023-02-23
Also published as: JP7226649B1; JPWO2023021575A1

Abstract

A brake state judgment device for servo motors is obtained whereby the state of brakes can be determined by using an acceleration sensor fixed to the outside of a case.　The servo motor brake state judgment device comprises a rotation force generation unit (2), a rotational axis (3), a brake (100), a case (111), an acceleration sensor (12), and a state judgment unit (102). The case (111) is provided so as to cover the rotation force generation unit (2) and the brake (100). The acceleration sensor (12) is disposed on the outside of the case (111) and is fixed so as to contact the case (111).

Description

Servo motor brake state determination device and brake state determination device

The present disclosure relates to a device for determining the state of an electromagnetic brake.

To determine the state of the electromagnetic brake, visually check the operating status of the brake plunger and check for any abnormalities by listening to the operating sound during operation. This state determination depends on the experience or intuition of the inspection operator. In addition, the variation in inspection accuracy is large. As a means to solve these problems, an acceleration sensor is provided on the brake plunger. As a result, the state of the brake can be determined based on the signal data acquired by the sensor installed inside the brake. There is also a technique for diagnosing the electromagnetic brake when the electromagnetic brake is released and when the electromagnetic brake is applied by detecting the acceleration when the brake plunger operates. (For example, see Patent Document 1)

JP 2004-123270

　In the electromagnetic brake condition diagnosis device described above, there was a problem that there was no space to install the acceleration sensor inside the housing for small brakes such as servo motors.

The present disclosure has been made in order to solve the problems described above, and an object thereof is to provide a brake state determination device that performs brake abnormality diagnosis without being restricted by the size or shape of the sensor. It is something to do.

A brake state determination device for a servomotor according to the present disclosure includes a rotational force generation unit that generates a rotational force, a rotational shaft that is rotated by the rotational force generated by the rotational force generation unit, and a rotational shaft that communicates with each other to prevent rotation of the rotational shaft. A brake for braking, a housing that covers the rotational force generating unit and the brake, an acceleration sensor that is arranged outside the housing and is fixed so as to be in contact with the housing, and the acceleration acquired by the acceleration sensor and the brake are normal. and a state determiner for determining the state of the brake by comparing it with the acceleration in the operating state.

According to the brake state determination device for a servomotor of the present disclosure, even in a small motor in which it is difficult to install an acceleration sensor inside the housing, there is no restriction on the size or shape of the sensor, and the sensor can be installed as necessary. Since it is detachable, it has the effect of being applicable to a wide range of devices.

1 is a configuration diagram showing a brake state determination device for a servomotor according to Embodiment 1; FIG. FIG. 4 is a configuration diagram showing another form of the braking state determination device for a servomotor according to Embodiment 1; FIG. 4 is a diagram of a state signal and a brake command signal when the brake according to Embodiment 1 is in a normal state and the brake is released; FIG. 5 is a diagram showing an example in which the magnitude of acceleration is different from that in a normal state due to an abnormality in the brake according to Embodiment 1; FIG. 4 is a diagram of a state signal and a brake command signal when the brake according to Embodiment 1 operates the brake in a normal state; FIG. 5 is a diagram showing an example in which the magnitude of acceleration differs from that in a normal state due to an abnormality in the brake according to Embodiment 1; FIG. 4 is a flowchart showing processing of a state determiner when releasing a brake according to Embodiment 1; 4 is a diagram showing an amplitude threshold value, a maximum magnitude of acceleration, and a sampling period used for state determination according to Embodiment 1. FIG. FIG. 5 is a flowchart showing processing of a state determiner when operating a brake according to Embodiment 1; 4 is a diagram showing an amplitude threshold value, a maximum magnitude of acceleration, and a sampling period used for state determination according to Embodiment 1. FIG. FIG. 11 is a diagram showing an example in which the first brake response time is shortened due to brake abnormality according to the second embodiment; FIG. 9 is a diagram showing an example in which the first brake response time is lengthened due to a brake abnormality according to Embodiment 2; FIG. 10 is a diagram showing an example in which the second brake response time is shortened due to brake abnormality according to the second embodiment; FIG. 10 is a diagram showing an example in which the second brake response time is lengthened due to brake abnormality according to the second embodiment; FIG. 10 is a flowchart showing processing of a state determiner when releasing a brake according to Embodiment 2; FIG. 9 is a diagram showing time thresholds, first brake response times, and sampling intervals used for state determination according to Embodiment 2; FIG. 9 is a flowchart showing processing of a state determiner when operating a brake according to Embodiment 2; FIG. 9 is a diagram showing time thresholds, second brake response times, and sampling intervals used for state determination according to Embodiment 2; FIG. 10 is a diagram comparing a state waveform acquired when the brake is released in a normal state and a state waveform acquired when the brake is released in a state where the brake is in an abnormal state according to the third embodiment; FIG. 11 is a flowchart showing processing of a state determiner when releasing a brake according to Embodiment 3; FIG. 10 is a diagram comparing state waveforms acquired when the brake is operated in a normal state and state waveforms acquired when the brake is operated in an abnormal state according to the third embodiment; FIG. 11 is a flowchart showing processing of a state determiner when operating a brake according to Embodiment 3;

The embodiments will be described in detail below based on the drawings. In addition, the embodiment described below is an example. Also, each embodiment can be executed in combination as appropriate.

Embodiment 1.
FIG. 1 is a configuration diagram of a braking state determination device for a servomotor according to Embodiment 1 of the present invention. As shown in FIG. 1, the brake state determination device for a servomotor includes a rotational force generator 2 that generates a rotational force, a rotational shaft 3 that rotates by the rotational force generated in the rotational force generator 2, and a rotational shaft 3. A brake 100 for braking the rotation of the rotating shaft 3, a housing 111 covering the rotational force generating unit 2 and the brake 100, and a housing 111 arranged outside the housing 111 and fixed so as to be in contact with the housing 111, an acceleration sensor 12 for detecting the acceleration of the brake 100; and a state determiner 102 for determining the state of the brake 100 by comparing the acceleration acquired by the acceleration sensor 12 with the acceleration when the brake 100 is operating normally. It has

The rotating shaft 3 is rotated by the rotating force generated by the rotating force generating section 2 . The brake rotor 4 has a friction material 5 and rotates integrally with the rotating shaft 3 by the rotating force generated in the rotating force generating portion 2 .

The brake 100 is composed of a brake rotor 4, a coil 7, a field 8, a spring 9 and an armature 10, and brakes the rotation of the rotating shaft 3. A field 8 containing a coil 7 is attached to the brake 100, and a spring 9 having an armature 10 at its tip is attached to the field 8. - 特許庁

The housing 111 is provided so as to cover the rotational force generating section 2 and the brake 100 . The acceleration sensor 12 is arranged outside the housing 111 and fixed so as to contact the housing 111 . The method of attaching the acceleration sensor 12 to the housing 111 is, for example, a fixing method using screws or an adhesive, and it is sufficient if the vibration of the housing 111 caused by the brake 100 can be measured. The acceleration sensor 12 detects the acceleration due to the vibration of the housing 111 and outputs the state signal as an electrical signal. be. The state determiner 102 is, for example, a servo amplifier or the like, and may be configured to process signal data acquired by the acceleration sensor 12 on a server to determine the state of the brake 100 .

The state determiner 102 includes an input section 112 to which the output of the digital converter 101 and the output of the brake main controller 107 are input, a RAM (Random Access Memory) 103 that temporarily stores the output of the digital converter 101, and a normal state. A read-only memory (ROM) 104 that stores a state signal or a threshold value for judging the state of the brake, and a process for judging the real-time state of the brake by comparing the data stored in the ROM 104 and the data stored in the RAM 103 and an output unit 113 for outputting the determination result. The output from the output unit 113 is input to the indicator 106 that displays brake abnormality. Also, the output of the brake main controller 107 that outputs a brake command signal, which is a signal for operating or releasing the brake, is input to the input section 112 of the state determiner 102 and the digital/analog converter 108 . The digital/analog converter 108 analog-converts the signal from the brake main controller 107 and then outputs the converted signal to the brake drive circuit 110 . A brake drive circuit 110 supplies power from a brake power source 109 to the coil 7 based on the signal from the digital/analog converter 108 .

It should be noted that the brake state determination device according to the present embodiment is intended for a small motor such as a servomotor that is difficult to install because there is no space for installing the acceleration sensor 12 due to its design. offer. Since it is difficult to install the acceleration sensor 12 inside the brake 100 for the servomotor, the acceleration sensor 12 is installed so as to be in contact with the outside of the housing 111 to determine the state of the brake 100 . Also, even if the motor is larger than the servomotor, it can be similarly applied if there are many design restrictions and it is difficult to install the acceleration sensor 12 inside.

Regarding the housing in which the acceleration sensor 12 in this embodiment is installed, the housing is provided so as to cover the rotational force generating section 2 and the brake 100 . 2 shows another form of FIG. 1, in which the motor housing 1 and the brake housing 11 are provided adjacent to each other. As shown in FIG. 2, the housing 111 may include the motor housing 1 and the brake housing 11 which are adjacent to each other, and the acceleration sensor 12 is provided outside the motor housing 1 or the brake housing 11. and fix it so that it touches the In that case, it is desirable that the rotational force generating unit 2 is arranged in the motor housing 1 and the brake 100 is arranged in the brake housing 11, but is not limited thereto. It is sufficient if the acceleration sensor 12 can detect it.

The operation when operating the brake 100 will be described. The armature 10 can be displaced in the direction of the friction material 5 installed on the brake rotor 4 by the extension of the spring 9 . When the armature 10 is displaced in the direction of the friction material 5 by a certain amount or more due to the expansion of the spring 9, the armature 10 collides with the friction material 5, and the armature 10 is no longer displaced in the direction of the friction material 5. Since the spring 9 can also generate an extension force, a pressure contact force that presses the armature 10 against the friction material 5 is generated. A frictional force is generated between the armature 10 and the friction material 5 due to the pressure contact force that presses the armature 10 against the friction material 5 , and a force for braking the brake rotor 4 is generated. Since the brake rotor 4 is fixed to the rotating shaft 3, the rotating shaft 3 can be braked.

The operation when releasing the brake 100 will be described. A magnetic flux is generated between the coil 7 and the armature 10 by applying a voltage to the coil 7 . The generated magnetic flux generates an attractive force that attracts the armature 10 , and this attractive force exceeds the extension force of the spring 9 , thereby displacing the armature 10 toward the field 8 . At this time, the armature 10 is pulled away from the friction material 5 and no friction occurs between the armature 10 and the friction material 5, so that the brake 100 is released.

That is, when the brake main controller 107 outputs a signal to operate the brake 100, the brake drive circuit 110 stops supplying electric power to the coil 7, and the armature 10 is pressed against the friction material 5 to brake the brake. 100 is activated. On the other hand, when the brake master controller 107 is outputting a signal to release the brake 100 , the brake drive circuit 110 supplies power to the coil 7 to pull the armature 10 away from the friction material 5 to release the brake 100 .

Next, the relationship between the state signal and the brake command signal will be described with reference to FIGS. 3 to 6. FIG.
First, the relationship between the state signal and the brake command signal when the brake 100 is released will be described. FIG. 3 shows the state signal and the brake command signal when the brake 100 is released in a normal state. Here, it is assumed that when the output of the brake command signal is 1, the brake main controller 107 outputs a signal to open the brake 100 . It is also assumed that when the output of the brake command signal is 0, the brake main controller 107 outputs a signal for operating the brake 100 . When the brake command signal is 0, the motor is in a stopped state, so the magnitude of the acceleration is a small value close to 0. Next, when the brake command signal becomes 1, electric power is supplied to the coil 7 and magnetic flux is generated between the coil 7 and the armature 10 , and the armature 10 is attracted to the coil 7 . The vibration generated at this time propagates to the housing 111, and the state signal appears as an attenuated wave as shown in FIG.

In (a) and (b) of FIG. 4, the solid line indicates the state signal when the brake 100 is released in the normal state, and the broken line indicates the state signal when the brake 100 is released in the abnormal state. FIG. 4(c) shows the brake command signal when the brake 100 is switched from operating (brake command signal: 0) to released (brake command signal: 1). FIG. 4(a) shows an example in which the brake has an abnormality and the magnitude of acceleration is smaller than the magnitude of acceleration in the normal state. FIG. 4(b) shows an example in which the brake has an abnormality and the magnitude of the acceleration is larger than the magnitude of the acceleration in the normal state. As shown in FIG. 4(a), when foreign matter enters the brake, the slidability of the armature 10 is reduced, and the magnitude of acceleration is reduced. Further, as shown in FIG. 4B, when the elastic force of the spring 9 decreases, the force with which the coil 7 attracts the armature 10 becomes relatively large. Become.

Next, the relationship between the state signal and the brake command signal when the brake 100 operates will be described. FIG. 5 shows the state signal and the brake command signal when the brake 100 operates in a normal state. Here, it is assumed that when the output of the brake command signal is 1, the brake main controller 107 outputs a signal to open the brake 100 . It is also assumed that when the output of the brake command signal is 0, the brake main controller 107 outputs a signal for operating the brake 100 . When the brake command signal switches from 1 to 0, the magnitude of the acceleration is a small value close to 0 because the motor is in a steady state. Next, when the brake command signal becomes 0 and the electric power to the coil 7 is cut off, the extension force of the spring 9 presses the armature 10 against the friction material 5 . The vibration generated at this time propagates to the housing 111, and the state signal appears as an attenuated wave as shown in FIG.

In FIGS. 6A and 6B, the solid line indicates the state signal when the brake 100 is operated when the brake 100 is normal, and the broken line indicates the state signal when the brake 100 is operated when the brake 100 is abnormal. indicated by FIG. 6(c) shows the brake command signal when the brake 100 is switched from released (brake command signal: 1) to actuated (brake command signal: 0). FIG. 6A shows an example in which the brake 100 has an abnormality and the magnitude of acceleration is smaller than the magnitude of acceleration in the normal state. FIG. 6B shows an example in which the brake 100 has an abnormality and the magnitude of acceleration is greater than the magnitude of acceleration in the normal state. As shown in FIG. 6(a), when the elastic force of the spring 9 is reduced, the displacement acceleration of the armature 10 is reduced. Further, as shown in FIG. 6B, when there is an abnormality in the joint between the rotating shaft 3 and the brake rotor 4, the brake rotor 4 vibrates more than in the normal state, so the magnitude of the acceleration becomes larger than in the normal state.

Next, operation of the state determiner 102 will be described with reference to FIGS. 7 to 10. FIG.
First, the processing of the state determiner 102 when the brake 100 is released will be described with reference to FIGS. FIG. 7 is a flow chart showing the processing of the state determiner 102, and FIG. 8 shows state signals and brake command signals around the time when the brake 100 is released. In FIG. 8A, the solid line indicates the state signal, the dotted lines indicate the amplitude thresholds th1 and th2, the broken lines indicate the amplitude thresholds th3 and th4, the sampling interval, and the magnitude of the acceleration in the sampling interval. shows the maximum value (maximum amplitude) _A2 of . FIG. 8(b) shows the brake command signal. A state determiner 102 determines the state of the brake 100 based on the state signal included in the sampling interval. This sampling interval is set so as to include an interval from the moment the armature 10 operates until the attenuation wave generated by the operation of the armature 10 appears sufficiently. Here, as an example, state signals corresponding to the sampling number N ₁ are acquired from the time when the brake command signal changes from 0 to 1. FIG. At that time, the sampling number _N1 is set to a value that sufficiently includes the damped waves generated by the operation of the armature 10 .

The amplitude threshold values th1 to th4 in the present embodiment are the amplitude threshold values of the brake 100 determined in advance within the range in which the brake 100 is operating normally from the maximum amplitude of the acceleration when the brake 100 is operating normally. Refers to the threshold value set for judging the state. If the maximum amplitude _A2 of acceleration is smaller than the amplitude threshold value th1 or th2, it is judged to be abnormal. Although the amplitude thresholds th1 and th2 may have different magnitudes, they are assumed to have the same magnitude as an example here. Also, the amplitude threshold values th1 and th2 are preferably set smaller than the maximum amplitude of the acceleration acquired when the brake 100 is released in the normal state. Similarly, when the maximum amplitude _A2 of acceleration is greater than the amplitude threshold th3 or th4, it is determined to be abnormal. Although the amplitude thresholds th3 and th4 may have different magnitudes, they are assumed to have the same magnitude as an example here. Also, the amplitude thresholds th3 and th4 are preferably set to be larger than the maximum amplitude of the acceleration acquired when the brake 100 is released while the brake 100 is in a normal state. For example, it is preferable to set the amplitude thresholds th1 to th4 with the maximum amplitude _A2 of acceleration when the brake 100 is in a normal state being 0.6 [m/s2].

Next, the processing of the state determiner 102 will be described using the flowchart of FIG. Processing begins when the brake command signal changes from 0 to 1. In step S1, as described above, the state signal is obtained from the time when the brake command signal changes from 0 to 1 until the sampling number _N1 . Next, in step S2, the maximum value (maximum amplitude) of the magnitude of acceleration is determined as _A2 from the state signal acquired in step S1, and the process proceeds to step S3. At S3, _A2 is compared with the amplitude threshold values th1 to th4 described above to determine the state of the brake 100. FIG.

(Number 1)
th1<A ₂ Formula (1)

(Number 2)
|th2|<A ₂ Formula (2)

(Number 3)
th3>A ₂ formula (3)

(Number 4)
|th4|>A ₂ Formula (4)

When all of the above expressions (1) to (4) are satisfied, it is determined that the state of the brake 100 is normal, and the operation of the state determiner 102 is terminated. In other cases, the state of the brake 100 is determined to be abnormal, and in step S4 an alarm is displayed to warn that the state of the brake 100 is abnormal.
The processing of the state determiner 102 when the brake 100 operates will be described with reference to FIGS. 9 and 10. FIG. FIG. 9 is a flow chart showing the processing of the state determiner 102 when the brake 100 operates. In (a) of FIG. 10, the solid line indicates the state signal, the dotted line indicates threshold values th5 and th6, the broken line indicates threshold values th7 and th8, the sampling interval, and the maximum value of the magnitude of acceleration in the sampling interval ( maximum amplitude) _A4 . FIG. 10(b) shows the brake command signal. The state determiner 102 determines the state of the brake 100 based on the state signal included in the sampling interval shown in FIG. 10(a). For example, the sampling interval is the interval from the time when the brake command signal changes from 1 to 0 until the number of samples reaches _N4 _. value.

Similar to when the brake 100 is released as described above, the amplitude thresholds th5 to th8 in the present embodiment are calculated from the maximum acceleration amplitude when the brake 100 is operating normally. It means a threshold value set for judging a predetermined state of the brake 100 in the operating range. If the maximum amplitude _A4 of acceleration is smaller than the amplitude threshold th5 or th6, the state of the brake 100 is determined to be abnormal. Although the amplitude thresholds th5 and th6 may have different magnitudes, they are assumed to have the same magnitude as an example here. Also, the magnitudes of amplitude thresholds th5 and th6 are preferably set smaller than the maximum amplitude of acceleration when brake 100 is operated in a normal state. Similarly, when the maximum acceleration amplitude _A4 is greater than the amplitude threshold th7 or th8, the state of the brake 100 is determined to be abnormal. Although the amplitude thresholds th7 and th8 may have different magnitudes, they are assumed to have the same magnitude as an example here. Also, the amplitude threshold values th7 and th8 are preferably set larger than the maximum amplitude of acceleration when the brake 100 operates in a normal state. For example, it is preferable to set the amplitude thresholds th5 to th8 with the maximum amplitude _A4 of the acceleration when the brake 100 is in the normal state being 0.6 [m/s2].

Next, the processing described above will be described with reference to the flow chart of FIG. The processing of FIG. 9 starts when the brake command signal changes from 1 to 0. First, in step S5, as described above, the state signal is acquired from the time when the brake command signal changes from 1 to 0 until the number of samples reaches _N4 . Next, in step S6, the maximum value (maximum amplitude) of acceleration is determined as _A4 from the obtained state signal, and the process proceeds to step S7. At S7, _A4 is compared with the amplitude threshold values th5 to th8 described above to determine the state of the brake 100. FIG.

(Number 5)
th5<A ₄ Formula (5)

(Number 6)
|th6|<A ₄ formula (6)

(Number 7)
th7>A ₄ formula (7)

(Number 8)
|th8|>A Formula ₄ (8)

When all of the above expressions (5) to (8) are satisfied, the state of the brake 100 is determined to be normal, and the operation of the state determiner 102 ends. Otherwise, the process moves to step S8, displays an alarm on the display 106, and then terminates the processing of the state determiner 102. FIG.

As described above, the state of the brake 100 can be determined based on the magnitude of acceleration acquired by the acceleration sensor 12 installed in the housing 111. Therefore, even in a small brake where it is difficult to install an acceleration sensor due to its design, the size of the sensor can be reduced. It is applicable to a wide range of devices because it is not restricted by the size or shape and the sensor can be attached and detached as necessary.

Embodiment 2.
In the first embodiment, the brake state determination device that determines the state of the brake 100 based on the magnitude of acceleration acquired by the acceleration sensor 12 is shown. A method of determining the state of the brake 100 based on the brake response time up to the point of time will be described. In this embodiment, the configuration itself is the same as that of the first embodiment, and only the operation of the state determiner 102 is different, so the details will be omitted.

A relationship between the state signal and the brake command signal will be described. In this embodiment, the time from when the brake command signal from the brake main controller 107 is switched to the brake operating state to when the brake 100 is switched to the released state is the first brake response time (T ₂ ), and the brake command signal A second brake response time (T ₄ ) is defined as the time from switching to the brake released state until the brake 100 switches to the operating state.

First, the case when the brake 100 is released will be described. When the brake 100 is released, the relay circuit of the brake drive circuit 110 is closed after the brake command signal is switched from 0 to 1, and power is supplied to the coil 7 . After that, the force that attracts the armature 10 due to the magnetic flux generated between the coil 7 and the armature 10 exceeds the extension force of the spring 9 . When the armature 10 is separated from the friction material 5, the brake 100 is released. Therefore, as shown in FIG. 11, the brake 100 is released after a certain period of time or more has elapsed since the brake command signal was switched from 0 to 1. Also, the first brake response time _T2 changes depending on the state of the brake 100 . For example, when the elastic force of the spring 9 decreases due to plastic deformation of the spring 9, the attractive force for separating the armature 10 from the friction material 5 _decreases . may be shorter. On the other hand, when foreign matter enters the brake 100, the slidability of the armature 10 is lowered, so the first brake response time _T2 may become longer as shown in FIG. Further, when the friction material 5 wears, the moving distance of the armature 10 increases, so the first brake response time _T2 may increase.

Next, the operation of brake 100 will be described. When the brake command signal becomes 0, the relay circuit of the brake drive circuit 110 is opened and the power supply to the coil 7 is cut off. After that, when the magnetic flux between the coil 7 and the armature 10 becomes smaller and the force with which the coil 7 attracts the armature 10 becomes smaller than that of the spring 9, the armature 10 is displaced in the direction of the friction material 5, and the brake 100 is operated. Therefore, as shown in FIG. 5, the brake 100 operates after a certain period of time or more has elapsed since the brake command signal changed from 1 to 0. Also, this second brake response time _T4 varies depending on the state of the brake 100. FIG. For example, when the magnetic flux generated between the coil 7 and the armature 10 decreases due to an abnormality in the coil 7, the extension force of the spring 9 relatively increases _. may be shorter. On the other hand, when foreign matter enters the inside of the brake 100, the slidability of the armature 10 is lowered, so that the second brake response time _T4 may become longer as shown in FIG.

The operation of state determiner 102 in this embodiment will be described.
First, the operation of the state determiner 102 for determining the state of the brake 100 based on the first brake response time _T2 when the brake 100 is released will be described with reference to FIGS. A state determiner 102 determines the state of the brake 100 based on the state signal included in the sampling interval shown in FIG. For example, the sampling interval is the interval from the time when the brake command signal changes from 0 to 1 until the sampling number _N11 . The number of samplings _N11 is set to a value that allows sufficient attenuation waves generated by the operation of the armature 10 to be obtained.

The first brake response time _T2 is the time from the time when sampling is started to the first time when the state signal becomes below or above a certain level, taking into account noise and the like. th11 and th12 are defined as threshold values for determining the first time, and the time from the time when the brake command signal changes from 0 to 1 to the first time when the state signal becomes less than th12 or greater than th11 is defined as the first time. Assume that the brake response time is _T2 . Although th11 and th12 may have different sizes, they are assumed to have the same size as an example here.

The time thresholds T13 and T14 are states of the brake 100 determined in advance within a range in which the brake 100 is operating normally from the first brake response time _T2 in which the brake 100 is operating normally. It is a threshold value set for judging If the first brake response time _T2 is smaller than the time threshold T13 or larger than the time threshold T14, it is determined that the brake 100 is abnormal. Therefore, for example, the time thresholds T13 and T14 should be set such _that T13 is smaller than the first brake response time T2 and T14 is larger than the first brake response time _T2 (T13< _T2 <T14). For example, the time thresholds T13 and T14 may be determined assuming that the first brake response time _T2 in the brake normal state is 0.5 [s]. Further, depending on the state of the brake 100, there may be no data in which the state signal is th12 or less or th11 or more in the sampling period. Assuming that the maximum value of the state signal is A ₁₁ and the minimum value is A ₁₂ , it is determined that the brake 100 is abnormal when either of the following equations (9) or (10) is satisfied.

(Number 9)
th11>A Formula ₁₁ (9)

(Number 10)
th12<A ₁₂ Formula (10)

The above processing will be described with reference to the flowchart of FIG. When the brake command signal changes from 0 to 1, the processing shown in FIG. 15 starts. In step S11, as described above, the state signal is obtained from the time when the brake command signal changes from 0 to 1 until the number of samplings reaches N ₁₁ , and the process proceeds to S12. In S12, it is determined whether the formula (9) or (10) is satisfied. If the conditions are satisfied, it is determined that the brake 100 has an abnormality, and after performing an alarm display process in S15, the process ends. If neither formula (9) nor (10) is satisfied in S12, the process proceeds to S13.

In S13, the first brake response time _T2 is determined by the method described above, and then the process proceeds to S14. In S14, it is determined whether or not the following formula (11) is satisfied.

(Number 11)
T13< _T2 <T14 Formula (11)

If the condition of formula (11) is not satisfied, it is determined that there is an abnormality in the brake 100, an alarm is displayed on the display 106 in S15, and the process is terminated. If the condition is satisfied in S14, it is determined that the brake 100 is in a normal state, and the process ends.

Next, the operation of the state determiner 102 that determines the state of the brake 100 based on the second brake response time _T4 when the brake 100 is operated will be described. A state determiner 102 determines the state of the brake 100 based on the state signal included in the sampling interval shown in FIG. For example, the sampling interval is the interval from the time when the brake command signal changes from 1 to 0 until the number of samplings reaches _N12 . The number of samplings _N12 is set to a value that can sufficiently acquire damped waves generated by the operation of the armature 10 .

The second brake response time _T4 is the time from the time when sampling is started to the first time when the state signal becomes below or above a certain level, taking into account noise and the like. th15 and th16 are defined as threshold values for determining the first time, and the time from the time when the brake command signal changes from 0 to 1 to the first time when the state signal becomes less than or equal to th16 or greater than or equal to th15 is defined as a second time. Assume that the brake response time is _T4 . Although th15 and th16 may have different sizes, they are assumed to have the same size as an example here.

The time thresholds T17 and T18 determine the state of the brake 100 in a range in which the brake 100 is operating normally from the second brake response time _T4 in which the brake 100 is operating normally. It is a threshold value set for judgment. If the second brake response time _T4 is less than the time threshold T17 or greater than the time threshold T18, it is determined that the brake 100 is abnormal. Therefore, for example, the time thresholds T17 and T18 should be set such that T17 is smaller than the first brake response time _T2 and T18 is larger than the first brake response time _T2 (T17< _T4 <T18). For example, the thresholds th17 and th18 may be determined by setting _T4 to 1.0 [s] in the brake normal state. Further, depending on the state of the brake 100, there may be no data in which the state signal is th16 or less or th15 or more in the sampling interval. Let the maximum value of the state signal be _A13 and the minimum value be _A14 . At this time, if the following formula (12) or formula (13) is satisfied, it is determined that the brake 100 is abnormal.

(Number 12)
th15>A Formula ₁₃ (12)

(Number 13)
th16<A Formula ₁₄ (13)

When the brake command signal changes from 1 to 0, the process of determining the state when the brake 100 is released starts. In step S16 in FIG. 16, as described above, the state signal is obtained from the time when the brake command signal changes from 1 to 0 until the number of samples reaches _N12 , and the process moves to step S17. In S17, it is determined whether the formula (12) or formula (13) is satisfied. If the condition is satisfied, it is determined that there is an abnormality in the brake 100, an alarm display process is performed in S20, and then the process ends. If neither formula (12) nor formula (13) is satisfied, the process proceeds to S18. In S18, the second brake response time _T4 is determined by the method described above, and the process proceeds to S19. In S19, it is determined whether the following formula (14) is satisfied.

(number 14)
T17< _T4 <T18 Formula (14)

If the condition of expression (14) is not satisfied, it is determined that there is an abnormality in the brake 100, and the processing is terminated after performing alarm display processing in S20. If the condition of formula (14) is satisfied in S19, it is determined that the brake 100 is in a normal state, and the process ends.

As described above, in the brake state determination device of Embodiment 2, it is possible to determine the state of the brake 100 based on the first brake response time _T2 or the second brake response time _T4 . Therefore, even in a small brake where it is difficult to install an acceleration sensor due to its design, there is no restriction on the size or shape of the sensor, and the sensor can be attached and detached as necessary, so it can be applied to a wide range of devices.

Embodiment 3.
In the third embodiment, the state of the brake 100 is determined based on the results of comparison between the learned state waveform, which is time-series data obtained when the brake 100 is in a normal state, and the state waveform obtained from the acceleration sensor 12 in real time. Explain how. In this embodiment, the configuration itself is the same as that of the first embodiment, and only the operation of the state determiner 102 is different, so the details will be omitted.

The operation of state determiner 102 in this embodiment will be described.
First, the processing of the state determiner 102 when the brake 100 is released will be described with reference to FIGS. 19 and 20. FIG. The state determiner 102 acquires a state waveform so as to include data from the moment when the armature 10 operates when the brake 100 is in a normal state until the attenuation wave generated by the operation of the armature 10 appears sufficiently, and uses it as a learned state. Waveform. Here, as an example, state waveforms for N ₃₁ samples are acquired from the time when the brake command signal changes from 0 to 1. FIG. The sampling number _N31 is set to a value that sufficiently includes damping waves generated by the operation of the armature 10 . Let the learned state waveform acquired at this time be XOL.

Also, let XOR be the state waveform acquired in real time when the brake 100 is released. Similarly, when the number of XOR samples is N ₃₁ and the i-th data is expressed as XOR _i , XOR _i is the data at the time when the brake command signal changes from 0 to 1. At this time, the error amount E1 representing the difference between the learned state waveform and the real-time state waveform is defined as Equation (15).

(Number 15)

Formula (15)

Here, as an example, the sum of the squares of the differences between the XOL and XOR at each point is used as the error amount, but for example, the sum of the absolute values of the differences between the XOL and XOR at each point may be used as the error amount. FIG. 19 shows the state waveform acquired when the brake 100 is released when the brake 100 is normal, and the state waveform acquired when the brake 100 is released when the brake 100 is abnormal is shown by the broken line. As shown in FIG. 19, when the brake 100 is released when there is an abnormality in the brake 100, the acceleration may decrease or the first brake response time may become longer. Here, as an example, the case where the magnitude of the acceleration is small is shown, but there are cases where the magnitude of the acceleration is large. Similarly, the first brake response time may also be shortened. Therefore, when there is an abnormality in the brake 100, the error amount E1 becomes larger than the error amount E1 in the normal state. When the relationship between the error amount E1 and the preset threshold value th21 does not satisfy the following formula (16), it can be determined that the state of the brake 100 is abnormal.

(Number 16)
E1<th21 Formula (16)

The above processing will be described with reference to the flow chart of FIG. When the brake command signal changes from 0 to 1, the process of determining the state of brake 100 when brake 100 is released is started. In S31, the state determiner 102 acquires state waveforms for N ₃₁ samples, and the process proceeds to S32. In S32, the error amount E1 defined by the equation (15) is determined, and the process proceeds to S33. In S33, it is determined that there is an abnormality if the equation (16) is not satisfied. If it is determined to be abnormal, the process proceeds to S34, displays an alarm on the display 106, and then terminates the processing of the state determination device 102. FIG. On the other hand, if the formula (16) is satisfied in S33, the brake 100 is determined to be normal, and the processing of the state determiner 102 ends.

Next, processing of the state determiner 102 when the brake 100 is operated will be described with reference to FIGS. 21 and 22. FIG. The state determiner 102 acquires a state waveform so as to include a section from the moment when the armature 10 operates when the brake 100 is in a normal state until the attenuation wave generated by the operation of the armature 10 sufficiently appears, and sets it as a learned state waveform. . Here, as an example, state waveforms for N ₄₂ samples are obtained from the time when the brake command signal changes from 1 to 0. FIG. The sampling number _N42 is set to a value that sufficiently includes damped waves generated by the operation of the armature 10. FIG. Let the learned state waveform at this time be XCL. The i-th learned state waveform data is represented as XCL _i . Also, let XCR be a state waveform acquired in real time by the acceleration sensor 12 when the brake 100 is operated. Similarly, the number of XCR samples is _N42 , and the i-th data is represented as XCR _i . XCR _i is data at the time when the brake command signal changes from 1 to 0. At this time, the error amount E2 representing the difference between the learned state waveform and the real-time state waveform is defined as the following equation (17).

(number 17)

Equation (17)

Here, as an example, the sum of the squares of the differences between XCL and XCR at each point is used as the error amount, but for example, the sum of the absolute values of the differences between XCL and XCR at each point may be used as the error amount. FIG. 21 shows a state waveform obtained when the brake 100 is operated in a normal state with a solid line, and a state waveform obtained when the brake 100 is operated with an abnormality in a broken line. As shown in FIG. 21, when the brake 100 is operated in a state where the brake 100 is abnormal, the magnitude of the acceleration may become small, or the second brake response time may become long. Here, an example in which the magnitude of the acceleration decreases is shown as an example, but it may increase in some cases. Similarly, the response time may also be shortened. Therefore, the difference between the values of the sampling points of the state waveforms obtained when the brake 100 is in a normal state and when it is in an abnormal state becomes large. Therefore, when the relationship between E2 and the preset threshold value th22 does not satisfy the following formula (18), it can be determined that the brake 100 has an abnormality.

(Number 18)
E2<th22 Equation (18)

The above processing will be described with reference to the flow chart of FIG. Processing is started when the brake command signal changes from 1 to 0. In S35, state waveforms corresponding to N ₄₂ samples are acquired, and the process proceeds to S36. In S36, the error amount E2 defined by Equation (17) is determined, and the process proceeds to S37. In S37, if the expression (18) is not satisfied, the process proceeds to S38, displays an alarm on the display 106, and then terminates the processing of the state determiner 102. FIG. On the other hand, if the formula (18) is satisfied in S37, the brake 100 is determined to be in a normal state, and the processing of the state determiner 102 ends. Thus, it is possible to determine the state of the brake 100 based on the result of comparing the learned state waveform and the real-time state waveform.

As described above, in the third embodiment, the state of the brake 100 is determined based on the result of comparing the learned state waveform and the real-time state waveform. Since the sensor is not restricted by the size or shape of the sensor, and the sensor can be attached and detached as necessary, it can be applied to a wide range of devices.

1 Motor housing, 2 Rotational force generator, 3 Rotating shaft, 4 Brake rotor, 5 Friction material, 7 Coil, 8 Field, 9 Spring, 10 Armature, 11 Brake housing, 12 Acceleration sensor, 100 Brake, 101 Digital conversion device, 102 state determiner, 103 RAM, 104 ROM, 105 CPU, 106 display, 107 brake main controller, 108 digital/analog converter, 109 brake power supply, 110 brake drive circuit, 111 housing, 112 input section, 113 output unit, 114 determination unit

Claims

a rotational force generator that generates a rotational force;
a rotating shaft rotated by the rotating force generated in the rotating force generating unit;
a brake that communicates with the rotating shaft and brakes the rotation of the rotating shaft;
a housing that covers the rotational force generating unit and the brake;
an acceleration sensor arranged outside the housing and fixed so as to be in contact with the housing;
a state determiner that determines the state of the brake by comparing the acceleration acquired by the acceleration sensor with the acceleration in the state in which the brake is operating normally;
A braking state determination device for a servo motor having
2. The housing includes a motor housing that covers the rotational force generating section and a brake housing that covers the brake, and the motor housing and the brake housing are adjacent to each other. 3. A brake state determination device for a servomotor according to claim 1.
The brake state determination device for a servo motor according to claim 1 or 2, wherein the state determiner determines the state of the brake using the maximum amplitude of acceleration acquired by the acceleration sensor.
The state determiner compares a predetermined amplitude threshold within a range in which the brake operates normally with the maximum amplitude of the acceleration acquired by the acceleration sensor to determine the state of the brake. 4. The brake state determination device for a servomotor according to claim 3.
The amplitude threshold is a binary value within a range in which the brake operates normally, and it is determined that the brake is normal when the acceleration acquired by the acceleration sensor is between the two values. 5. The brake state determination device for a servomotor according to claim 4, wherein:
The state determiner determines the state of the brake using the brake response time obtained from the acceleration acquired by the acceleration sensor, and the brake response time is the time required for the brake to switch from an open state to an operating state. 3. A servomotor brake state determination device according to claim 1 or 2, characterized in that it is a time until said brake is switched from an operating state to an open state.
The state determiner compares the brake response time in a state in which the brake is operating normally with a predetermined time threshold within a range in which the brake is operating normally, and determines the state of the brake. 7. The brake state determination device for a servomotor according to claim 6, wherein the determination is made as follows.
The time threshold is a binary value within a range in which the brake operates normally, and it is determined that the brake is normal when the brake response time is between the two values. 8. The brake state determination device for a servomotor according to claim 7.
a rotational force generator that generates a rotational force;
a rotating shaft rotated by the rotating force generated by the rotating force generating unit;
a brake that brakes the rotation of the rotating shaft;
a housing that covers the rotational force generating unit and the brake, with which the rotating shaft communicates;
an acceleration sensor fixed to the outside of the housing;
a state determiner that determines the state of the brake by comparing a learned state waveform, in which the brake is determined to be in a normal state, with a waveform acquired by the acceleration sensor;
A braking state determination device for a servo motor having
9. The housing comprises a motor housing covering the rotational force generating section and a brake housing covering the brake, wherein the motor housing and the brake housing are adjacent to each other. 3. A brake state determination device for a servomotor according to claim 1.
an input unit for inputting acceleration obtained by an acceleration sensor fixed to the outside of the housing covering the rotational force generating unit and the brake;
The brake state is determined by comparing the acceleration input to the input unit with a predetermined threshold within a range of normal operation from the maximum amplitude of the acceleration when the brake is operating normally. a judgment unit to
an output unit that outputs the determination result of the determination unit;
A brake state determiner for a servo motor having
an input unit for inputting acceleration acquired by an acceleration sensor fixed to the outside of a housing that covers the rotational force generating unit or the brake;
Predetermined in a range in which the brake is operating normally from the acceleration input to the input unit and the brake response time until the brake is switched from the released state to the operating state or from the operating state to the released state obtained from the acceleration a determination unit for determining the state of the brake by comparing with the threshold value obtained;
an output unit that outputs the determination result of the determination unit;
A brake state determiner for a servo motor having