Backlash-amount measurement apparatus, backlash-amount measurement method and computer readable medium

A rotation control unit performs a rotation process of rotating a servomotor which is connected to a device via a power transmission means. A waveform-data acquisition unit performs a waveform-data acquisition process of acquiring waveform data when the servomotor is rotated. A determination unit performs a determination process of determining whether or not rotation has been transmitted to the device when the servomotor is rotated, based on the waveform data. A calculation unit ends a repetition process of repeating a search process, the search process being constituted by the rotation process, the waveform-data acquisition process, and the determination process, when it is determined that the rotation has been transmitted to the device, and calculates as a backlash amount, a sum of a rotation amount in the repetition process, the rotation amount being an amount by which the rotation control unit has rotated the servomotor in the rotation process.

TECHNICAL FIELD

The present disclosure relates to a backlash-amount measurement apparatus, an after-learning-learned-model generation apparatus, a learning-purpose-data generation apparatus, a backlash-amount measurement method, an after-learning-learned-model generation method, a learning-purpose-data generation method, a backlash-amount measurement program, an after-learning-learned-model generation program, and a learning-purpose-data generation program.

BACKGROUND ART

When a device is operated by using a servomotor, power of the servomotor is transmitted to the device via a power transmission means having a gear, a belt, a coupling, a joint, and the like. However, backlash such as a gap between the gears exists in the power transmission means, and the power equivalent to the backlash is not transmitted to the device even when the servomotor rotates. Thus, an erroneous difference equivalent to the backlash is caused, between a position of the device expected by a motion controller which controls the device, and an actual position of the device.

In order to correct this erroneous difference, the motion controller has a backlash correction function that does not count a position command equivalent to the backlash as a current position, when a direction of rotation of the servomotor changes. If backlash correction is implemented, a backlash correction amount needs to be set as a parameter of the motion controller in advance.

Conventionally, a backlash amount has been measured by rotating the servomotor manually by a person. However, since it requires an enormous amount of labor, a technique of automatically estimating the backlash amount has been developed. For example, Patent Literature 1 estimates the backlash amount based on correlation data between amplitude from a motor torque command and amplitude from position feedback.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, a conventional technique estimates as the backlash amount, the amplitude from the position feedback, obtained when a second derivative of the amplitude from the motor torque command is maximum. Therefore, it is necessary to rotate the servomotor for a while even after the gears engage with each other and the power is transmitted to the device. That is, there has been a problem that measurement of the backlash amount takes a long time since not only measurement time until the power is transmitted, but also measurement time after the power is transmitted is necessary.

The present disclosure aims to solve the above-described problem and realizes a backlash-amount measurement apparatus which measures a backlash amount of a power transmission means in a shorter period of time.

Solution to Problem

A backlash-amount measurement apparatus according to the present disclosure includes: a rotation control unit to perform a rotation process of rotating by a certain amount, a servomotor which is connected to a device via a power transmission means; a waveform-data acquisition unit to perform a waveform-data acquisition process of acquiring waveform data obtained when the servomotor is rotated by the certain amount by the rotation control; a determination unit to perform a determination process of determining whether or not rotation has been transmitted to the device when the servomotor is rotated by the certain amount by the rotation control, based on the waveform data acquired by the waveform-data acquisition process; and a calculation unit to cause a repetition process of repeating a search process to be executed, the search process being constituted by the rotation process by the rotation control unit, the waveform-data acquisition process by the waveform-data acquisition unit, and the determination process by the determination unit, when the determination unit determines that the rotation of the servomotor has not been transmitted to the device in the determination process, to end the repetition process when the determination unit determines that the rotation of the servomotor has been transmitted to the device in the determination process, and to calculate as a backlash amount, a sum of a rotation amount in the repetition process, the rotation amount being an amount by which the rotation control unit has rotated the servomotor in the rotation process.

Advantageous Effects of Invention

A backlash-amount measurement apparatus according to the present disclosure includes: a rotation control unit to perform a rotation process of rotating by a certain amount, a servomotor which is connected to a device via a power transmission means; a waveform-data acquisition unit to perform a waveform-data acquisition process of acquiring waveform data obtained when the servomotor is rotated by the certain amount by the rotation control; a determination unit to perform a determination process of determining whether or not rotation has been transmitted to the device when the servomotor is rotated by the certain amount by the rotation control, based on the waveform data acquired by the waveform-data acquisition process; and a calculation unit to cause a repetition process of repeating a search process to be executed, the search process being constituted by the rotation process by the rotation control unit, the waveform-data acquisition process by the waveform-data acquisition unit, and the determination process by the determination unit, when the determination unit determines that the rotation of the servomotor has not been transmitted to the device in the determination process, to end the repetition process when the determination unit determines that the rotation of the servomotor has been transmitted to the device in the determination process, and to calculate as a backlash amount, a sum of a rotation amount in the repetition process, the rotation amount being an amount by which the rotation control unit has rotated the servomotor in the rotation process. Hence, the backlash-amount measurement apparatus determines whether or not the rotation of the servomotor has been transmitted to the device, each time the servomotor is rotated by the certain amount, and calculates the backlash amount at a time when it is determined that the rotation of the servomotor is transmitted to the device. Therefore, it is unnecessary to rotate the servomotor after the power is transmitted, and it is possible to calculate the backlash amount in a shorter period of time.

DESCRIPTION OF EMBODIMENTS

First Embodiment

FIG.1is a configuration diagram illustrating configurations of an FA (Factory Automation) system1000and a backlash-amount measurement apparatus100according to a first embodiment.

The FA system1000is production equipment for products and includes the backlash-amount measurement apparatus100, a device1, a servomotor2, a power transmission means3, a mode setting means4, and a vibration sensor5.

The device1is a machine which actually produces products, and operates by power transmitted from the servomotor2via the power transmission means3.

The servomotor2is connected to the device1via the power transmission means, rotates according to input electric power, and transmits the power to the device1. Further, the servomotor2rotates according to a control instruction input from the backlash-amount measurement apparatus100. The configuration of the backlash-amount measurement apparatus100will be described later. Further, the servomotor2is connected to a servo amplifier (not illustrated) which amplifies the electric power input from a power supply (not illustrated).

The power transmission means3transmits the power of the servomotor2to the device1and is constituted by a gear, a ball screw, a belt, and the like. There exists backlash such as a gap between the gears in the power transmission means3.

The mode setting means4is for the user to input into the backlash-amount measurement apparatus100, a mode signal indicating an operation mode. A keyboard and the like are adopted as the mode setting means4.

The vibration sensor5detects vibration of the device1and outputs to the backlash-amount measurement apparatus100, vibration data indicating the vibration of the device1. Further, the vibration sensor5is assumed to be connected to the device1.

The backlash-amount measurement apparatus100measures a backlash amount of the power transmission means3and includes a rotation control unit11, a waveform-data acquisition unit12, a determination unit13, and a calculation unit14. Further, in the first embodiment, the backlash-amount measurement apparatus100also serves as a programmable logic controller which controls a regular production operation of the device1.

The rotation control unit11performs rotation control to rotate the servomotor2, that is, the rotation control unit11is a motion controller for the servomotor2. In the first embodiment, the rotation control unit11performs a rotation process of rotating by a certain amount, the servomotor2which is connected to the device1via the power transmission means3. Further, each time the rotation process is performed, the rotation control unit11outputs to the calculation unit14, rotation-amount information indicating the rotation amount by which the servomotor2has been rotated.

Here, the certain amount by which the rotation control unit11rotates the servomotor2is preferably smaller than the backlash amount of the power transmission means3. This certain amount may be decided based on a rule of thumb, or the backlash amount may be measured at a time of initial setting of the production equipment in advance, and then a value equal to or smaller than the backlash amount may be adopted.

The waveform-data acquisition unit12acquires waveform data obtained when the servomotor2rotates. In the first embodiment, the waveform-data acquisition unit12performs a waveform-data acquisition process of acquiring the waveform data obtained when the servomotor2is rotated by the certain amount by the rotation process. Here, the waveform data indicates changes over time in amplitude, and is vibration data or sound data, for example. In the first embodiment, the waveform-data acquisition unit12acquires the vibration data from the vibration sensor5, as the waveform data.

The determination unit13determines whether or not the rotation of the servomotor2has been transmitted to the device1, based on the waveform data. In the first embodiment, the determination unit13performs a determination process of determining whether or not the rotation has been transmitted to the device1when the servomotor2is rotated by the certain amount by the rotation process, based on the waveform data.

Further, in the first embodiment, the determination unit13determines that the rotation of the servomotor2has been transmitted to the device1, when the amplitude of the waveform indicated in the waveform data is equal to or larger than a first threshold value and the waveform indicated in the waveform data continues for a period of time equal to or longer than a second threshold value. Here, determination as to whether or not the waveform continues for the period of time equal to or longer than the second threshold value is realized by for example, generating an envelope of the waveform and determining whether or not a period of time when amplitude of the generated envelope is equal to or larger than a certain threshold value is equal to or longer than the second threshold value.

Here, each threshold value may be set by a designer based on a rule of thumb, or each threshold value may be set performing the rotation process and the waveform-data acquisition process at an initial time of adjusting the FA system1000, and using the waveform data obtained at that time. Alternatively, each threshold value may be decided using the amplitude, duration, and the amplitude of the envelope in the waveform data in the first rotation process at a time of backlash-amount measurement.

The calculation unit14calculates as the backlash amount of the power transmission means3, the rotation amount of the servomotor2generated from a time when the rotation control unit11starts rotating the servomotor2until a time when the determination unit13determines that the rotation of the servomotor2has been transmitted to the device1. More specifically, in the first embodiment, a calculation unit14causes a repetition process of repeating a search process to be executed, the search process being constituted by the rotation process by the rotation control unit11, the waveform-data acquisition process by the waveform-data acquisition unit12, and the determination process by the determination unit13, when the determination unit13determines that the rotation of the servomotor2has not been transmitted to the device1in the determination process, ends the repetition process when the determination unit13determines that the rotation of the servomotor2has been transmitted to the device1in the determination process, and calculates as a backlash amount of the power transmission means3, a sum of a rotation amount in the repetition process, the rotation amount being an amount by which the rotation control unit11has rotated the servomotor2in the rotation process.

Here, the calculation unit14calculates the rotation amount of the servomotor2by adding up the rotation amount indicated in the rotation-amount information input from the rotation control unit11, using a built-in adding-up means. Further, the sum of the rotation amount is a rotation amount after resetting the adding-up means to zero. That is, when the sum of the rotation amount is referred to, the rotation amount before resetting the adding-up means to zero is not taken into consideration.

Further, the calculation unit14employs waiting time between each search process. Therefore, in an occasion when the calculation unit14executes the repetition process, the calculation unit14causes the next search process to be executed after a waiting for a certain period of time predetermined subsequent to the previously performed search process. This is because if the next rotation process is performed before the vibration of the device1converges, the amplitude of the waveform and the change over time are not measured accurately and whether or not the power has been transmitted to the device1cannot be determined accurately.

Further, the calculation unit14also serves as a mode decision unit which decides the operation mode based on the mode signal input from the mode setting means4. Here, the operation mode is a production mode for the device1to perform the regular production operation or a backlash-amount measurement mode for measuring the backlash amount of the power transmission means3. Below, mainly a backlash auto-adjustment mode will be described.

Next, a hardware configuration of the backlash-amount measurement apparatus100according to the first embodiment will be described. Each function of the backlash-amount measurement apparatus100is realized by a computer.FIG.2is a configuration diagram illustrating an example of a hardware configuration of the computer which realizes the backlash-amount measurement apparatus100, according to the first embodiment.

Hardware illustrated inFIG.2includes a processing device10000such as a CPU (Central Processing Unit), and a storage device10001such as a ROM (Read Only Memory) or a hard disk.

The rotation control unit11, the waveform-data acquisition unit12, the determination unit13, and the calculation unit14which are illustrated inFIG.1are realized by the processing device10000executing a program stored in the storage device10001. Here, the above-described configuration is not limited to a configuration realized by a single processing device10000and a single storage device10001, and may be a configuration realized by a plurality of processing devices10000and a plurality of storage devices10001.

Further, a method of realizing each function of the backlash-amount measurement apparatus100is not limited to the above-described combination of hardware and program, and may be realized by only hardware such as an LSI (Large Scale Integrated Circuit) obtained by implementing the program in the processing device. Alternatively, a part of the functions may be realized by dedicated hardware, and the other part of the functions may be realized by a combination of processing device and program.

The backlash-amount measurement apparatus100according to the first embodiment is constituted as above.

Next, an operation of the backlash-amount measurement apparatus100according to the first embodiment will be described.

FIG.3is flowcharts illustrating the operation of the backlash-amount measurement apparatus100according to the first embodiment.

Further, below, the operation of the backlash-amount measurement apparatus100corresponds to a backlash-amount measurement method, and the program which causes the computer to execute the operation of the backlash-amount measurement apparatus100corresponds to a backlash-amount measurement program. Further, an operation of the rotation control unit11corresponds to a rotation control step, an operation of the waveform-data acquisition unit12corresponds to a waveform-data acquisition step, an operation of the determination unit13corresponds to a determination step, and an operation of the calculation unit14corresponds to a calculation step.

First, in step S101, a user sets the backlash-amount measurement apparatus100to the backlash-amount measurement mode, using the mode setting means4. Upon receiving from the mode setting means4, a control signal indicating that the mode is set to the backlash-amount measurement mode, the calculation unit14causes below-described initial position setting to be executed.

In step S102, the rotation control unit11rotates the servomotor2by the certain amount in a normal direction.

In step S103, the waveform-data acquisition unit12acquires from the vibration sensor5, vibration data obtained by detecting vibration of the device1when the servomotor2is rotated by the certain amount in step S101. The waveform-data acquisition unit12outputs the acquired vibration data to the determination unit13.

In step S104, the determination unit13determines whether or not the rotation of the servomotor2has been transmitted to the device1, based on the input vibration data. More specifically, the determination unit13monitors the input vibration data and determines whether or not the amplitude is equal to or larger than the first threshold value and the waveform continues for the period of time equal to or longer than the second threshold value. When the determination unit13determines that the rotation of the servomotor2has not been transmitted to the device1, the process returns to step S102after a waiting for the certain period of time, and the rotation control unit11rotates the servomotor2by the certain amount in the normal direction again. When the determination unit13determines that the rotation of the servomotor2has been transmitted to the device1, the process proceeds to step S105, and the calculation unit14resets the built-in adding-up means to zero.

The above-described processes from step S102to step S105are the initial position setting, and also processes of setting the adding-up means to zero in a state where gears of the power transmission means3engage with each other, as preparation for the measurement of the backlash amount.

After an end of the initial position setting and a subsequent waiting for the certain period of time, the rotation control unit11rotates the servomotor2by a certain amount in an opposite direction in step S106. Further, the rotation control unit11outputs to the calculation unit14, the rotation-amount information indicating the rotation amount by which the servomotor2has been rotated.

In step S107, the calculation unit14adds the rotation amount to the adding-up means based on the input rotation-amount information.

In step S108, the waveform-data acquisition unit12acquires from the vibration sensor5, the vibration data obtained by detecting the vibration of the device1when the servomotor is rotated by the certain amount in step S106. The waveform-data acquisition unit12outputs the acquired vibration data to the determination unit13.

In step S109, the determination unit13determines whether or not the rotation of the servomotor2has been transmitted to the device1, based on the input vibration data. More specifically, the determination unit13monitors the input vibration data and determines whether or not the amplitude is equal to or larger than the first threshold value and the waveform continues for the period of time equal to or longer than the second threshold value. When the determination unit13determines that the rotation of the servomotor2has not been transmitted to the device1, the process returns to step S106after a waiting for the certain period of time, and the servomotor2is rotated by the certain amount in the opposite direction again. When the determination unit13determines that the rotation of the servomotor2has been transmitted to the device1, the process proceeds to step S110, and the calculation unit14reads the adding-up means and calculates the sum of the rotation amount of the servomotor2as a backlash amount A.

Here, with use ofFIG.4, specific examples of processes from step S106to step S110will be described.

FIG.4is a conceptual diagram for explaining a specific example of the operation of the backlash-amount measurement apparatus100according to the first embodiment.

InFIG.4, when the rotation of the servomotor2is increased by a fixed amount each time, from a state of standstill, a position of a movable portion of the device1does not change unless the power of the servomotor2is transmitted to the device1. Therefore, the amplitude of the vibration is small like the first and second times of addition of the rotation amount inFIG.4, and a period of time of the vibration is short. At the third time of the addition of the rotation amount, since the power of the servomotor2is transmitted to the device1, the position of the movable portion of the device1changes, and the device1itself vibrates. Therefore, compared with the first and second times, the amplitude in the vibration data is larger, and the period of time until the vibration converges is longer. The determination unit13determines whether or not the power of the servomotor2has been transmitted to the device1via the power transmission means3, by recognizing such changes in the vibration.

Returning toFIG.3, descriptions of the subsequent operation will be given.

Although, it is possible to terminate the operation after the above-described processes, the backlash-amount measurement apparatus100according to the first embodiment calculates the backlash amounts both in the normal direction and the opposite direction and calculates an average of these amounts as a final backlash amount in order to reduce errors in the measurement. The processes described above are the operation of measuring the backlash amount in the opposite direction, and below, descriptions will continue regarding an operation of measuring the backlash amount in the normal direction.

In step S111, the calculation unit14resets the built-in adding-up means to zero.

In step S112, the rotation control unit11rotates the servomotor2by the certain amount in the normal direction. Further, the rotation control unit11outputs to the calculation unit14, the rotation-amount information indicating the rotation amount by which the servomotor2has been rotated.

In step S113, the calculation unit14adds the rotation amount to the adding-up means based on the input rotation-amount information.

In step S114, the waveform-data acquisition unit12acquires from the vibration sensor5, vibration data obtained by detecting the vibration of the device1when the servomotor2is rotated by the certain amount in step S111. The waveform-data acquisition unit12outputs the acquired waveform data to the determination unit13.

In step S115, the determination unit13determines whether or not the rotation of the servomotor2has been transmitted to the device1, based on the input vibration data. More specifically, the determination unit13monitors the input vibration data and determines whether or not the amplitude is equal to or larger than the first threshold value and the waveform continues for the period of time equal to or longer than the second threshold value. When the determination unit13determines that the rotation of the servomotor2has not been transmitted to the device1, the process returns to step S112after a waiting for the certain period of time, and the servomotor2is rotated by the certain amount in the normal direction again. When the determination unit13determines that the rotation of the servomotor2has been transmitted to the device1, the process proceeds to step S116, and the calculation unit14reads the adding-up means and records the sum of the rotation amount of the servomotor2as a backlash amount B.

In step S117, the calculation unit14calculates an average value of the backlash amount A and the backlash amount B, as the final backlash amount.

In step S118, the calculation unit14sets the calculated backlash amount as a corrected amount, in the rotation control unit11.

By the above-described operation, the backlash-amount measurement apparatus100according to the first embodiment determines whether or not the rotation of the servomotor2has been transmitted to the device1, each time the servomotor2is rotated by the certain amount, and the backlash-amount measurement apparatus100calculates the backlash amount at a time when it is determined that the rotation of the servomotor2has been transmitted to the device1. Therefore, it is unnecessary to rotate the servomotor2after the power is transmitted, and it is possible to calculate the backlash amount in a shorter period of time.

Further, the backlash-amount measurement apparatus100according to the first embodiment determines that the rotation of the servomotor2has been transmitted to the device1, when the amplitude of the waveform indicated in the waveform data is equal to or larger than the first threshold value and the waveform indicated in the waveform data continues for the period of time equal to or longer than the second threshold value. Therefore, it is possible to determine whether or not the power has been transmitted, based on rules. Hence, a designer and a user can set the threshold values as necessary, which enables handling various types of situations flexibly.

Further, the backlash-amount measurement apparatus100according to the first embodiment acquires as the waveform data, the vibration data indicating the vibration of the device1, detected by the vibration sensor5connected to the device1. Therefore, it is possible to acquire the waveform data which includes less noise from a surrounding environment, and measure the backlash amount highly accurately.

Further, in the above, the servomotor2is rotated in the normal direction first to perform the initial position setting, and then the first search process is performed in the opposite direction. However, the servomotor2may be rotated in the opposite direction first to perform the initial position setting, and then the first search process may be performed in the normal direction.

Second Embodiment

Next, a backlash-amount measurement apparatus200according to a second embodiment will be described.

In the first embodiment, the backlash-amount measurement apparatus100waits for the predetermined certain period of time after the servomotor2is rotated once. Meanwhile, the second embodiment describes the backlash-amount measurement apparatus200which measures duration of the waveform indicated in the waveform data, sets this duration as the waiting time, and measures the backlash amount in a shorter period of time. Below, mainly matters different from the first embodiment will be described.

FIG.5is a configuration diagram illustrating configurations of an FA system2000and the backlash-amount measurement apparatus200according to the second embodiment. The FA system2000is production equipment for products and includes the backlash-amount measurement apparatus200, a device201, a servomotor202, a power transmission means203, a mode setting means204, and a vibration sensor205. Further, the backlash-amount measurement apparatus200includes a rotation control unit211, a waveform-data acquisition unit212, a determination unit213, a calculation unit214, and a duration measurement unit215.

Here, in addition to the production mode and the backlash-amount measurement mode, a waveform-duration measurement mode is added as the operation mode of the backlash-amount measurement apparatus200.

Further, the duration measurement unit215is added as the configuration of the backlash-amount measurement apparatus200. The duration measurement unit215measures the duration of the waveform indicated in the waveform data when the determination unit213determines that the rotation of the servomotor202has not been transmitted to the device201. Here, a process that the duration measurement unit215measures the duration of the waveform is referred to as a duration measurement process.

Further, the calculation unit214according to the second embodiment sets the duration measured by the duration measurement unit215as the waiting time after the search process is executed and until the next search process is executed, in the repetition process.

That is, after the servomotor202rotates by the certain amount, the calculation unit214executes the next search process immediately after an elapse of the duration of the waveform measured by the duration measurement unit215. In other words, after the servomotor202rotates by the certain amount, the next search process is not executed until after the elapse of the duration of the waveform measured by the duration measurement unit215.

Since the other configurations are the same as those in the first embodiment, descriptions will be omitted. Also, a hardware configuration is the same as that in the first embodiment. As with the other units, the duration measurement unit215is also realized by the processing device executing the program stored in the storage device.

Next, with use ofFIG.6, an operation of the backlash-amount measurement apparatus200according to the second embodiment will be described.

FIG.6is a flowchart illustrating an operation of measuring the duration of the waveform by the backlash-amount measurement apparatus200, according to the second embodiment.

First, in step S201, the user sets the backlash-amount measurement apparatus200to the waveform-duration measurement mode, using the mode setting means204. After the waveform-duration measurement mode is set, the calculation unit214causes the rotation control unit211to execute the rotation process.

In step S202, the rotation control unit211rotates the servomotor202by the certain amount in the normal direction.

In step S203, the waveform-data acquisition unit212acquires from the vibration sensor5, vibration data obtained by detecting the vibration of the device201when the servomotor202is rotated by the certain amount in step S202. The waveform-data acquisition unit212outputs the acquired vibration data to the determination unit213and the duration measurement unit215.

In step S204, the determination unit213determines whether or not the rotation of the servomotor202has been transmitted to the device201, based on the input vibration data. More specifically, the determination unit213monitors the input vibration data and determines whether or not the amplitude is equal to or larger than the first threshold value and the waveform continues for the period of time equal to or longer than the second threshold value. When the determination unit213determines that the rotation of the servomotor202has not been transmitted to the device201, the process proceeds to step S205. When the determination unit213determines that the rotation of the servomotor202has been transmitted to the device201, the process ends.

When it is determined as NO in step S204, the duration measurement unit215measures the duration of the input waveform data and outputs to the calculation unit214, the duration information indicating the measured duration, in step S205. The calculation unit214sets the duration indicated in the input duration information, as the waiting time between each search process. After step S205, an operation of a backlash-amount measurement apparatus200ends.

Since the backlash-amount measurement apparatus200measures the duration of the waveform and sets the duration as the waiting time between each search process by the above-described operation, it is possible to measure the backlash amount in a shorter period of time.

Effect of the backlash-amount measurement apparatus200according to the second embodiment will be described in more detail.

When the servomotor202is rotated once and then the next rotation is started before the vibration of the device201converges, the next vibration may overlap the previous vibration. In such a situation, it is unlikely to be able to accurately determine whether or not the rotation of the servomotor202has been transmitted to the device201based on the vibration data. Therefore, in the first embodiment, a certain period of time is set in advance, and the next search process being the rotation process is not performed until the certain period of time elapses. Meanwhile, the backlash-amount measurement apparatus200according to the second embodiment sets the duration of the waveform as the waiting time. Consequently, it is possible to eliminate a waiting for an extra period of time and to measure the backlash amount in a shorter period of time. Further, it is possible to avoid a situation where the backlash amount cannot be accurately measured because of too short waiting time set by the designer or the user.

Further, since an operation regarding the backlash-amount measurement after setting the waiting time according to the above is the same as that in the first embodiment, descriptions will be omitted.

Below, a modification example of the backlash-amount measurement apparatus200according to the second embodiment will be described.

In the above, the operation of measuring the duration of the waveform is performed separately from the operation of measuring the backlash amount. However, the duration of the waveform may be measured from the waveform data obtained in the first rotation process when the backlash amount is measured.

In step S204described above, when the determination unit213determines that the rotation of the servomotor202has been transmitted to the device201, the operation ends. Alternatively, it is acceptable that the operation does not end and the servomotor202is rotated in the opposite direction. Besides, it is also acceptable that the duration of the waveform is measured from the waveform data at that time.

It is further acceptable that the processes from step S102to step S105in the first embodiment are executed to perform the initial position setting of the power transmission means203, before the process proceeds to step S202. It is possible to measure the duration of the waveform more certainly by executing these processes. Further, in the above-described case, in step S202, the servomotor202is supposed to be rotated in the opposite direction, not in the normal direction.

Third Embodiment

Next, the backlash-amount measurement apparatus300according to a third embodiment will be described.

The backlash-amount measurement apparatuses according to the first and second embodiments use as the waveform data, the vibration data indicating the vibration of a position in the device. Meanwhile, the backlash-amount measurement apparatus300according to the third embodiment uses as the waveform data, sound data obtained by detecting operation sound of the device. Below, mainly matters different from the first and second embodiments will be described.

FIG.7is a configuration diagram illustrating configurations of an FA system3000and the backlash-amount measurement apparatus300according to the third embodiment.

The FA system3000is production equipment for products and includes the backlash-amount measurement apparatus300, a device301, a servomotor302, a power transmission means303, a mode setting means304, and a sound sensor305. Further, the backlash-amount measurement apparatus300includes a rotation control unit311, a waveform-data acquisition unit312, a determination unit313, and a calculation unit314.

The sound sensor305is placed in the vicinity of the device301, detects the operation sound of the device301, and outputs to the backlash-amount measurement apparatus300, the sound data indicating the operation sound of the device301.

In the third embodiment, the waveform-data acquisition unit312acquires the sound data from the sound sensor305, as the waveform data.

Since the other configurations and operations are the same as those in the first embodiment, descriptions will be omitted.

It is possible to measure the backlash amount with a lower cost by using the sound sensor305instead of the vibration sensor5as described above.

Further, the technique in the second embodiment may be applied to the third embodiment. That is, also in the third embodiment, the backlash-amount measurement apparatus300may measure the duration of the sound indicated in the sound data, and set the measured duration as the waiting time between each search process.

Fourth Embodiment

Next, a fourth embodiment will be described.

The above-described backlash-amount measurement apparatuses according to the first to third embodiments automatically measure the backlash amount from the vibration or the sound. Meanwhile, a backlash-amount measurement apparatus400will be described which causes a display device to display a warning for the user of the device when the backlash amount is too large to be corrected.

When an element such as a gear, included in the power transmission means has small abrasion and a small backlash amount, the device can be controlled performing the correction. However, when the abrasion becomes large and the backlash amount becomes large, an act of keeping using an operation may lead to a breakdown of the power transmission means. For this reason, the backlash-amount measurement apparatus400according to the fourth embodiment sets in advance an upper limit on the backlash amount to be measured, that is the rotation amount of the servomotor. When the backlash amount exceeds this upper limit, the backlash-amount measurement apparatus400then ends the measurement of the backlash amount and displays for the user, a notification that the backlash amount exceeds the upper limit.

Below, mainly matters different from the first to third embodiments will be described.

FIG.8is a configuration diagram illustrating configurations of an FA system4000and the backlash-amount measurement apparatus400according to the fourth embodiment.

The FA system4000is production equipment for products and includes the backlash-amount measurement apparatus400, a device401, a servomotor402, a power transmission means403, a mode setting means404, a vibration sensor405, and a display device406. Further, the backlash-amount measurement apparatus400includes a rotation control unit411, a waveform-data acquisition unit412, a determination unit413, and a calculation unit414.

The display device406performs displaying for the user based on a control signal received from the calculation unit414. A display or the like is adopted as the display device406.

In the fourth embodiment,

the calculation unit414determines whether or not the sum of the rotation amount of the servomotor402in the repetition process is equal to or larger than a third threshold value, in each search process, and when it is determined that the sum of the rotation amount of the servomotor402is equal to or larger than the third threshold value, ends the repetition process regardless of whether or not the determination unit413determines that the rotation of the servomotor402has been transmitted to the device401.

Further, when it is determined that the sum of the rotation amount of the servomotor402is equal to or larger than the third threshold value, the calculation unit414transmits the control signal which causes the display device406to display the warning. Here, displaying the warning is, for example, to display a warning indicating that the backlash amount cannot be measured, to display a warning that prompts an overhaul of the production equipment, or the like.

Next, with use ofFIG.9, an operation of the backlash-amount measurement apparatus400according to the fourth embodiment will be described.

FIG.9is flowcharts illustrating the operation of the backlash-amount measurement apparatus400according to the fourth embodiment.

A matter different from the operation of the backlash-amount measurement apparatus100according to the first embodiment is mainly that when it is determined as NO in step S409, the process does not directly return to step S406, and step S410is performed in between. Similarly, an operation of step S417is performed between steps S416and S413.

When it is determined as NO in step S409, the calculation unit414determines whether or not the sum of the rotation amount of the servomotor402in the repetition process is equal to or larger than the third threshold value, in step S410. Here, when the calculation unit414determines that the sum of the rotation amount is equal to or larger than the third threshold value, the process proceeds to step S418. When the calculation unit414determines that the sum of the rotation amount is smaller than the third threshold value, the process returns to step S406. Operations in steps S416and S417are the same as those in steps S409and S410respectively.

When the process proceeds to YES after step S410or step S417, the calculation unit414transmits the control signal to the display device406in step S418. Then, upon receiving the control signal from the calculation unit414, the display device406displays the warning for the user.

By the above operation, the backlash-amount measurement apparatus400according to the fourth embodiment causes the display device406to display the warning, when the backlash amount exceeds the threshold value for correcting the backlash amount. This enables the user to recognize that the abrasion of the power transmission means403has become large, and consider the overhaul of the production equipment early.

Further, the technique in the second embodiment may be applied to the fourth embodiment. That is, also in the fourth embodiment, the backlash-amount measurement apparatus400may measure the duration of the waveform indicated in the waveform data, and set the measured duration as the waiting time between each search process.

Further, the technique in the third embodiment may be applied to the fourth embodiment. That is, the FA system4000may include the sound sensor instead of the vibration sensor405, and the backlash-amount measurement apparatus400may use the sound data as the waveform data.

Fifth Embodiment

Next, a backlash-amount measurement apparatus500according to a fifth embodiment will be described.

The backlash-amount measurement apparatuses according to the first to fourth embodiments determine whether or not the rotation of the servomotor has been transmitted to the device on a basis of rules, based on rules in the amplitude and the duration in the waveform data. Meanwhile, in the fifth embodiment, the backlash-amount measurement apparatus500will be described which determines whether or not the rotation of the servomotor has been transmitted to the device, using a learned model. This is derived from a consideration on a situation where the power transmission means is so complex that it is not determined whether or not the power of the device has been transmitted from the servomotor based on the amplitude of the vibration or sound waveform, or a length of time until the vibration converges, in automatic setting of the backlash amount.

FIG.10is a configuration diagram illustrating configurations of an FA system5000and the backlash-amount measurement apparatus500according to the fifth embodiment.

An FA system5000is production equipment for products and includes the backlash-amount measurement apparatus500, a device501, a servomotor502, a power transmission means503, a mode setting means504, a vibration sensor505, and a display device.

In the fifth embodiment, the backlash-amount measurement apparatus500includes a rotation control unit511, a waveform-data acquisition unit512, a determination unit513, a calculation unit514, a learning-purpose-data acquisition unit521, a learning unit522, a label attachment unit531, and a data-amount determination unit532. Here, the rotation control unit511, the waveform-data acquisition unit512, the determination unit513, and the calculation unit514constitute a utilization unit510. Further, the learning-purpose-data acquisition unit521and the learning unit522constitute a learned-model generation unit520. Further, the rotation control unit511, the waveform-data acquisition unit512, the calculation unit514, the label attachment unit531, and the data-amount determination unit532constitute a learning-purpose-data generation unit530.

Next, a hardware configuration of the backlash-amount measurement apparatus500according to the fifth embodiment will be described. Each function of the backlash-amount measurement apparatus500is realized by a computer.FIG.11is a configuration diagram illustrating an example of a hardware configuration of the computer which realizes the backlash-amount measurement apparatus500, according to the fifth embodiment.

Hardware illustrated inFIG.11includes a processing device50000such as a CPU (Central Processing Unit), and a storage device50001such as a ROM (Read Only Memory) or a hard disk.

The rotation control unit511, the waveform-data acquisition unit512, the determination unit513, the calculation unit514, the learning-purpose-data acquisition unit521, the learning unit522, the label attachment unit531, and the data-amount determination unit532which are illustrated inFIG.10are realized by the processing device50000executing a program stored in the storage device50001. Further, a function that the learning unit522stores a learned model and a function that the data-amount determination unit532stores learning-purpose data are realized by the storage device50001. Here, the above-described configuration is not limited to a configuration realized by a single processing device50000and a single storage device50001, and may be a configuration realized by a plurality of processing devices50000and a plurality of storage devices50001.

A method of realizing each function of the backlash-amount measurement apparatus500is not limited to the above-described combination of hardware and program, and may be realized by only hardware such as an LSI (Large Scale Integrated Circuit) obtained by implementing the program in the processing device. Alternatively, a part of the functions may be realized by dedicated hardware, and the other part of the functions may be realized by a combination of processing device and program.

The backlash-amount measurement apparatus500according to the fifth embodiment is constituted as above.

Below, the utilization unit510, the learned-model generation unit520, and the learning-purpose-data generation unit530will be described in a utilization phase, a learning phase, and a learning-purpose-data generation phase respectively.

First, the utilization unit510which measures the backlash amount, using an after-learning learned model will be described.

In the fifth embodiment, the determination unit513determines whether or not the rotation of the servomotor502has been transmitted to the device501, based on the waveform data, using the learned model. That is, the determination unit513acquires the after-learning learned model from the learning unit522which will be described later, and determines whether or not the power of the servomotor502has been transmitted to the device501, by inputting the waveform data into this learned model.

Here, the learned model used by the determination unit513is assumed to be obtained from learning of supervised learning. More specifically, the learned model outputs consistency information indicating whether or not the input waveform data is consistent with the waveform data which is obtained in advance from the learning conducted when the power of the servomotor502has been transmitted to the device501. When the pieces of waveform data are consistent with each other, the learned model outputs the consistency information indicating “consistent”. When the pieces of waveform data are inconsistent with each other, the learned model outputs the consistency information indicating “inconsistent”. Here, “consistent” is the same meaning as “transmission”, and “inconsistent” is the same meaning as “non-transmission”. Further, here, an act of determining whether or not the waveform data is consistent with the waveform data obtained in advance from the learning is referred to as waveform determination.

Further, for the consistency in the waveform determination, the pieces of waveform data do not need to be identical to each other precisely. When the types of waveforms indicated in the pieces of waveform data are the same, it is possible to conclude as “consistent”. Also, when the types of waveforms are different from each other, it is possible to conclude as “inconsistent”. Here, as the types of the waveform, there are two types, namely, the waveform obtained when the power of the servomotor502has been transmitted to the device501, and the waveform obtained when the power of the servomotor502has not been transmitted to the device501.

That is, when the input waveform data is consistent with the waveform data which is obtained in advance from the learning conducted when the power of the servomotor502has been transmitted to the device501, the determination unit513outputs a determination result indicating “transmission” which represents that the power has been transmitted. Further, when the input waveform data is not consistent with the waveform data which is obtained in advance from the learning conducted when the power of the servomotor502has been transmitted to the device501, or when the input waveform data is consistent with the waveform data which is obtained in advance from the learning conducted when the power of the servomotor502has not been transmitted to the device501, the determination unit513outputs a determination result indicating “non-transmission” which represents that the power has not been transmitted.

In the above, it is described that the determination unit513determines the waveform, using the learned model obtained from the learning by the learning unit522of the backlash-amount measurement apparatus500. However, the learned model may be acquired from the outside such as another learning device, and the determination unit513may determine the waveform based on this learned model.

The utilization unit510is constituted as above.

Next, with use ofFIG.12, an operation of measuring the backlash amount by the utilization unit510will be described.

FIG.12is flowcharts illustrating the operation of measuring the backlash amount by the utilization unit510, according to the fifth embodiment.

In steps S504, S509, and S515, the utilization unit510determines whether or not the rotation of the servomotor502has been transmitted to the device501, by inputting the waveform data into the leaned model.

Since the other operations are the same as those in the first embodiment, descriptions will be omitted.

By the above-described operation, the backlash-amount measurement apparatus500according to the fifth embodiment determines whether or not the rotation of the servomotor502has been transmitted to the device501, with use of the learned model. Therefore, it is possible to measure the backlash amount highly accurately even in a case where the power transmission means503is so complex that the transmission of the power from the servomotor502to the device501cannot be determined based on the amplitude of the vibration or sound waveform, or a length of time until the vibration converges.

Next, the learned-model generation unit520which generates the after-learning learned model will be described.

The learning-purpose-data acquisition unit521acquires as learning-purpose data, the waveform data obtained when the servomotor502connected to the device501via the power transmission means503is rotated, and the consistency information indicating whether or not the rotation of the servomotor502has been transmitted to the device501. That is, the learning-purpose-data acquisition unit521acquires as the learning-purpose data, the waveform data to which the consistency information is attached.

The learning unit522generates with use of the learning-purpose data, the learned model for determining whether or not the rotation of the servomotor502has been transmitted to the device501, based on the waveform data obtained when the servomotor502is rotated.

That is, the learning unit522performs learning for the learned model, based on the learning-purpose data input from the learning-purpose-data acquisition unit521. Further, before the learning, the learning unit522stores a before-learning learned model in advance. After the learning, the learning unit522stores the after-learning learned model.

As learning algorithm used by the learning unit522, publicly-known algorithm such as supervised learning, unsupervised learning, or reinforcement learning can be used. As an example, a case where a neural network is adopted will be described.

The learning unit522learns the determination on the waveform data, for example, by so-called supervised learning, according to a neural network model. Here, the supervised learning is a method of providing a learning device with a pair of input data and result (label) data, and causing the learning device to learn characteristics in the learning-purpose data and to infer the result from the input.

The neural network is constituted by an input layer configured with a plurality of neurons, an intermediate layer (hidden layer) configured with a plurality of neurons, and an output layer configured with a plurality of neurons. The intermediate layer may be one, two, or more layers.

For example, in the neural network having three layers as illustrated inFIG.13, when a plurality of inputs are input into input layers (X1 to X3), the values are multiplied by weight W1 (w11 to w16) and then the results are input into intermediate layers (Y1 to Y2). Then, the results are further multiplied by weight W2 (w21 to w26) and then output from output layers (Z1 to Z3). These output results vary depending on values of the weight W1 and the weight W2.

In the present embodiment, the neural network learns the waveform determination, by the so-called supervised learning, according to the combination of vibration data and consistency information which are the learning-purpose data acquired by the learning-purpose-data acquisition unit521.

That is, the neural network learns, by adjusting the weight W1 and the weight W2 so that the results output from the output layers after inputting into the input layers, the vibration data which is the learning data become close to the consistency information corresponding to the input waveform data.

The learning unit522generates the after-learning learned model by the above-described operation, and outputs the after-learning learned model.

Next, with use ofFIG.14, a process that the learned-model generation unit520generates the after-learning learned model will be described.

FIG.14is a flowchart illustrating an operation of the learned-model generation unit520according to the fifth embodiment.

Further, below, the operation of the learned-model generation unit520corresponds to an after-learning-learned-model generation method, and a program which causes the computer to execute the operation of the learned-model generation unit520corresponds to an after-learning-learned-model generation program. Further, an operation of the learning-purpose-data acquisition unit521corresponds to a learning-purpose-data acquisition step, and an operation of the learning unit522corresponds to a learning step.

In step S521, the learning-purpose-data acquisition unit521acquires the learning-purpose data in which the vibration data and the consistency information are associated with each other. Note that, it is premised that the vibration data and the consistency information are acquired at the same time. However, it is sufficient if the vibration data and the consistency information are input with an association with each other, Therefore, each of the vibration data and the consistency information may be acquired at different timings.

In step S522, the learning unit522learns the waveform determination, by the so-called supervised learning, according to the learning-purpose data acquired in step S521, and generates the after-learning learned model.

In step S523, the learning unit522stores the after-learning learned model generated by the learning unit522.

Next, the learning-purpose-data generation unit530which generates the learning-purpose data to be used for the learning will be described.

In the above, the utilization unit510and the learned-model generation unit520are described. Here, the learning-purpose-data generation unit530for generating the learning-purpose data to be input into the learned-model generation unit520will be described.

The learning-purpose-data generation unit530shares the rotation control unit511, the waveform-data acquisition unit512, and the calculation unit514with the utilization unit510.

The label attachment unit531attaches a label to the waveform data and generates the learning-purpose data. More specifically, the label attachment unit531generates the learning-purpose data by attaching to the waveform data, a non-transmission label indicating that the waveform data is obtained when the rotation of the servomotor502has not been transmitted to the device501, when the rotation amount of the servomotor502does not exceed a preset backlash amount, and by attaching to the waveform data, a transmission label indicating that the waveform data is obtained when the rotation of the servomotor502has been transmitted to the device501, when the rotation amount of the servomotor502exceeds the backlash amount. Here, the transmission label and the non-transmission label are equivalent to the consistency information. The transmission label is equivalent to “consistent” described in the utilization phase. The non-transmission label is equivalent to “inconsistent” described in the utilization phase.

Further, the label attachment unit531outputs the generated learning-purpose data to the data-amount determination unit532.

The data-amount determination unit532determines whether or not a sufficient amount of learning-purpose data generated by the label attachment unit531has been collected. For example, the data-amount determination unit532determines whether or not the enough amount of learning-purpose data has been collected, by determining whether or not the number of bytes of the learning-purpose data which has been input reaches the certain number of bytes. Further, the data-amount determination unit532stores the learning-purpose data which has been input, and outputs the learning-purpose data to the learning-purpose-data acquisition unit521according to a request from the learning-purpose-data acquisition unit521.

In the initial adjustment of the FA system5000, the user measures the backlash amount of the production equipment, using a dial gauge or the like, and stores the measured backlash amount in the label attachment unit531in advance.

Next, with use ofFIG.15, an operation of generating the learning-purpose data by the learning-purpose-data generation unit530will be described.

FIG.15is flowcharts illustrating the operation of the learning-purpose-data generation unit530according to the fifth embodiment.

Further, below, the operation of the learning-purpose-data generation unit530corresponds to a learning-purpose-data generation method, and a program which causes the computer to execute the operation of the learning-purpose-data generation unit530corresponds to a learning-purpose-data generation program. Further, an operation of the label attachment unit531corresponds to a label attachment step, and an operation of the data-amount determination unit532corresponds to a data-amount determination step.

In step S531, the calculation unit514resets the built-in adding-up means to zero.

In step S532, the calculation unit514adds to the adding-up means, a rotation amount to be instructed in step S533. Further, the calculation unit514reads a value of the adding-up means and outputs to the label attachment unit531, information indicating the sum of the rotation amount of the servomotor502.

In step S533, the rotation control unit511rotates the servomotor502by the certain amount in the normal direction.

In step S534, the waveform-data acquisition unit512acquires waveform data obtained when the servomotor502is rotated by the certain amount in step S533. The waveform-data acquisition unit512outputs the acquired waveform data to the label attachment unit531.

In step S535, the label attachment unit531compares the sum of the rotation amount indicated in the information input from the calculation unit514, with the backlash amount recorded in advance. When the sum of the rotation amount is smaller than the backlash amount, the process proceeds to step S536. Then, the label attachment unit531generates the learning-purpose data by attaching to the waveform data, the consistency information indicating “inconsistent”. After that, the process returns to step S532.

When the sum of the rotation amount is equal to or larger than the backlash amount in step S535, the process proceeds to step S537. Then, the label attachment unit531generates the learning-purpose data by attaching to the waveform data, the consistency information indicating “consistent”.

In step S538, the calculation unit514resets the built-in adding-up means to zero.

In step S539, the calculation unit514adds to the adding-up means, the rotation amount to be instructed in step S540. Further, the calculation unit514reads a value of the adding-up means and outputs to the label attachment unit531, information indicating the sum of the rotation amount of the servomotor502.

In step S540, the rotation control unit511rotates the servomotor502by the certain amount in the opposite direction.

In step S541, the waveform-data acquisition unit512acquires the waveform data obtained when the servomotor502is rotated by the certain amount in step S540. The waveform-data acquisition unit512outputs the acquired waveform data to the label attachment unit531.

In step S542, the label attachment unit531compares the sum of the rotation amount indicated in the information input from the calculation unit514, with the backlash amount recorded in advance. When the sum of the rotation amount is smaller than the backlash amount, the label attachment unit531generates the learning-purpose data by attaching to the waveform data, the consistency information indicating “inconsistent”, in step S543. After that, the process returns to step S539.

When the sum of the rotation amount is not smaller than the backlash amount in step S542, the process proceeds to step S544. Then, the label attachment unit531generates the learning-purpose data by attaching to the waveform data, the consistency information indicating “consistent”.

In step S545, the data-amount determination unit532determines whether or not a certain amount of learning-purpose data accumulated has been collected. When the data-amount determination unit532determines that the certain amount has been collected, the learning-purpose-data generation unit530ends the operation. When the data-amount determination unit532determines that the certain amount has not been collected, the process returns to step S531.

By the operation as above, the learning-purpose-data generation unit530can reduce labor to generate the learning-purpose data, by generating the learning-purpose data automatically. Further, it is possible to generate the pieces of learning-purpose data efficiently by alternating the rotation in the normal direction and the rotation in the opposite direction and generating the learning-purpose data at times of both the rotation in the normal direction and the rotation in the opposite direction.

Below, a modification example of the backlash-amount measurement apparatus500according to the fifth embodiment will be described.

In the above, a case where the supervised learning is applied as the learning algorithm is described. However, the learning algorithm is not limited to this. Instead of the supervised learning, the reinforcement learning, the unsupervised learning, semi-supervised learning, or the like can be applied as the learning algorithm.

Further, the learned-model generation unit520may learn the waveform determination according to pieces of learning-purpose data generated by a plurality of backlash-amount measurement apparatuses500. Note that, the learned-model generation unit520may acquire the pieces of learning-purpose data from the plurality of backlash-amount measurement apparatuses500used in the same area, or may use the pieces of learning-purpose data collected from the plurality of backlash-amount measurement apparatuses500each of which operates independently in different area, to learn the waveform determination. Further, it is possible to add/remove the backlash-amount measurement apparatus500which collects the learning-purpose data to/from a subject during the process. Furthermore, a learned model which has been used for learning the waveform determination in one backlash-amount measurement apparatus500may be applied to a different backlash-amount measurement apparatus500from this, and the waveform determination may be learned again to update the learned model in the different backlash-amount measurement apparatus.

Further, as the learning algorithm used by the learning unit522, deep learning (Deep Learning) which learns extraction of a feature itself may be used, and machine learning may be executed according to another publicly-known method such as genetic programming, inductive programming, or a support-vector machine, for example.

Further, in the above, a configuration having a single backlash-amount measurement apparatus500including the utilization unit510, the learned-model generation unit520, and the learning-purpose-data generation unit530is described. However, a different configuration is acceptable such as a configuration having each unit in a different apparatus, like a configuration with a utilization apparatus, an after-learning-learned-model generation apparatus, and a learning-purpose-data generation apparatus, for example. Further, another configuration having each unit on a cloud server is also acceptable.

Further, the technique in the second embodiment may be applied to the fifth embodiment. That is, also in the fifth embodiment, the backlash-amount measurement apparatus500may measure the duration of the waveform indicated in the waveform data, and set the measured duration as the waiting time between each search process.

Further, the technique in the third embodiment may be applied to the fifth embodiment. That is, the FA system5000may include the sound sensor instead of the vibration sensor505, and the backlash-amount measurement apparatus500may use the sound data as the waveform data.

INDUSTRIAL APPLICABILITY

The backlash-amount measurement apparatus according to the present disclosure is suitable to be used in an FA system.

REFERENCE SIGNS LIST