JP7192458B2 - Information processing device, information processing method and information processing program - Google Patents

Description

The present invention relates to an information processing device for detecting an abnormality in a servomotor mechanism.

A servomotor mechanism, which includes a servomotor and a driven device driven by the servomotor, is controlled in operation by a controller. When the controller detects an abnormality in the servomotor mechanism, it takes measures such as issuing an alarm. Some of such control devices monitor the torque value of the servomotor and detect an abnormality when the torque value exceeds the normal range. For example, Patent Literature 1 discloses detecting an abnormality when a torque value exceeds a threshold.

By the way, the servo motor mechanism is affected by temperature, and causes changes in coil resistance, thermal deformation, and the like. Therefore, even when the servomotor mechanism performs torque control of the servomotor to give a predetermined operation to the driven device, the torque of the servomotor also differs when the temperature changes. Therefore, the torque value for detecting an abnormality in the servomotor is affected by the temperature.

Patent Literature 1 discloses a system that reduces the influence of temperature on the torque value by performing temperature correction on the torque value. This system creates a torque value temperature correction formula based on the temperature characteristics of the torque value of the drive motor when the robot arm is operated at each temperature of the speed reducer. Then, when an abnormality is detected, the system performs temperature correction of the torque value using a temperature correction formula using the drive motor or speed reducer temperature measurement value obtained by the temperature sensor.

Japanese Patent Application Laid-Open No. 2006-281421 (published on October 19, 2006)

However, in the break-in state immediately after the operation of the servomotor mechanism is resumed after stopping the operation, the torque load tends to increase, and an abnormality may be erroneously detected even if the above torque correction is performed. be. In addition, the torque load fluctuates depending on the temperature and the time during which the operation is suspended. In particular, when the temperature is low, the torque load during break-in operation is greater than when the temperature is high. This increase in torque load causes erroneous detection of abnormality.

An object of one aspect of the present invention is to prevent erroneous detection of an abnormality in a torque value after operation is restarted.

The present invention adopts the following configurations in order to solve the above-described problems.

That is, the information processing apparatus according to one aspect of the present invention detects an abnormality that occurs in the operation of a drive mechanism having a driven device and a motor that drives the driven device, when the torque value of the motor exceeds a threshold value. and a threshold correction unit that corrects the threshold so that the threshold used in a predetermined period after the driving mechanism resumes operation after the rest period is larger than that during normal operation. ing.

According to the above configuration, it is possible to prevent erroneous detection of abnormality during the predetermined period after the rest period. In particular, the drive mechanism is likely to malfunction immediately after restarting after the idle period. Therefore, it is possible to quickly discover an abnormality that may occur immediately after the restart (immediately after the rest period ends).

The threshold correction unit may correct the threshold based on the temperature of the motor.

The torque value increases when the temperature is low immediately after the drive mechanism is restarted. Therefore, by correcting the threshold value based on the temperature of the motor, it is possible to quickly discover an abnormality that may occur immediately after the restart.

The threshold correction unit may correct the threshold based on the length of the idle period.

The torque value increases when the length of the pause period (pause time) is long. Therefore, by correcting the threshold value based on the pause time, it is possible to quickly discover an abnormality that may occur immediately after restarting.

The threshold correction unit may correct the threshold based on the number of operations of the drive mechanism during the predetermined period.

The torque value is the largest during the first operation immediately after starting, and decreases as the number of operations increases. Therefore, by correcting the threshold value based on the number of times of operation, it is possible to quickly discover an abnormality that may occur immediately after restarting.

The abnormality detection section may determine abnormality detection using an average of the torque values when the driven device moves between two predetermined points.

By averaging the torque values, it becomes possible to detect a wide range of abnormal points.

An information processing method according to one aspect of the present invention detects an abnormality occurring in an operation of a drive mechanism having a driven device and a motor for driving the driven device when a torque value of the motor exceeds a threshold. an abnormality detection step; and a threshold value correction step of correcting the threshold value so that the threshold value used in a predetermined period after the drive mechanism resumes operation after a rest period is larger than that during normal operation. .

According to one aspect of the present invention, it is possible to prevent erroneous detection of an abnormality in the torque value after restarting operation.

1 is a block diagram showing the configuration of a control system according to one embodiment of the present invention; FIG. 4 is a flow chart showing a preparatory processing procedure for determining whether there is an abnormality in the servo motor mechanism in the control system; 7 is a graph showing the relationship between the temperature variable and the temperature for calculating the offset amount of the torque value during the break-in period. 4 is a graph showing a relationship between a pause period variable and a pause time for calculating the offset amount; 4 is a graph showing the relationship between an operation number variable and the number of operations for calculating the offset amount. 7 is a graph showing changes in offset amount with respect to the number of operations during a break-in period. 4 is a flow chart showing a processing procedure for abnormality detection during break-in. FIG. 8 is a side view showing a ball screw drive stage as an example of a machine tool showing data necessary for the processing shown in FIG. 7; (a) to (c) are diagrams showing offset correction of the torque value by the control system. FIG. 4 is a diagram for explaining calculation of a torque correction value based on an offset with respect to a reference curve showing a temperature change of a torque value; FIG. 5 is a diagram showing the relationship between the number of times of operation and the correction value of the torque value;

Hereinafter, an embodiment (hereinafter also referred to as "this embodiment") according to one aspect of the present invention will be described based on the drawings.

§1 Application Example An example of a scene to which the present invention is applied will be described with reference to FIG.

FIG. 1 is a block diagram showing a schematic configuration of a control system 100 according to this embodiment.

As shown in FIG. 1 , the control system 100 includes a PLC (programmable logic controller) 1 (information processing device), a servo driver 2 , a servo motor mechanism 3 (driving mechanism), and a temperature sensor 4 . The servomotor mechanism 3 is controlled by the PLC 1 and includes a servomotor 31 and a machine tool 32 (driven part).

The control system 100 detects an abnormality based on the torque value of the servomotor 31 using the PLC1. Since the torque value is affected by temperature, the PLC 1 creates a reference curve plotting the reference value of the torque value according to the temperature. In addition, the PLC 1 also sets a threshold that defines a normal range centered on the reference curve. In addition, the PLC 1 sets the torque value that defines the reference curve immediately after the start of a predetermined period (break-in period) during which the servo motor mechanism 3 resumes operation after a period of rest (rest period). A formula for calculating an offset amount C for offsetting is created.

The PLC 1 calculates a correction value obtained by correcting the torque value during the break-in period for determining abnormality detection, detects an abnormality when the correction value exceeds a threshold, and detects an abnormality when the correction value is equal to or less than the threshold. do not. In calculating the correction value, the PLC 1 converts the offset amount C, which is calculated by applying the acquired variables to the above equation, to the actual torque value specified by the reference curve based on the actual torque value and temperature of the servomotor 31. A correction value is calculated by subtracting the offset amount X of the torque value of .

§2 Configuration Example A configuration example of the control system 100 according to the first embodiment will be described with reference to FIG.

The servomotor 31 is a motor that drives a machine tool 32 (driven device), and a rotary encoder for detecting a rotation angle and a rotation angular velocity is attached to the rotary shaft. The machine tool 32 is a driven part of a machine such as a robot, and has a mechanism that converts the rotational driving force generated by the servomotor 31 into a predetermined motion.

The servo driver 2 drives the servo motor 31 by applying torque as optimum driving energy according to the state quantity (rotation angle, rotation angular velocity, etc.) of the servo motor 31 based on the command received from the PLC 1 .

The PLC 1 includes a control section 11 that gives control commands to the servo driver 2 and a memory 12 . The control unit 11 generates command position, command speed and command acceleration for motion control given to the servo driver 2 . The control unit 11 also includes a pause time recording unit 111 and an operation number counting unit 112 . The rest time recording unit 111 measures the rest time during which the servo motor mechanism 3 is resting and stores it in the memory 12 . The number-of-operations counting unit 112 counts the number of repetitions of a predetermined operation performed by the servomotor mechanism 3 (the number of operations), and stores the number in the memory 12 .

The PLC 1 has a data acquisition section 13 , a data correction section 14 (threshold correction section), and an abnormality detection section 15 in order to detect an abnormality in the servomotor mechanism 3 .

The data acquisition unit 13 acquires the torque value of the servo motor 31 from the servo driver 2 and acquires the temperature of the servo motor 31 from the temperature sensor 4 using the communication function of the PLC 1 . Note that the torque value is obtained from the current value that the servo driver 2 outputs to the servo motor 31 . The temperature sensor 4 is arranged near the servomotor 31 and detects the temperature of the servomotor 31 . In addition, the data acquisition unit 13 acquires the pause time and the number of operations stored in the memory 12 .

The data correction unit 14 prepares the above-described reference curve and sets the threshold value, and prepares an equation for calculating the offset amount C, prior to determination of abnormality detection during the break-in period. Further, the data correction unit 14 calculates a correction value during the break-in period. In addition, the data correction unit 14 corrects the threshold so that the threshold used during the break-in period is larger than during normal operation.

The abnormality detection unit 15 determines whether or not the servomotor mechanism 3 is present, using the above correction value as a determination criterion.

An abnormality determination operation during the break-in period by the control system 100 configured as described above will be described.

First, prior to the abnormality determination process, a process of creating a calculation formula for calculating the offset amount C is performed.

FIG. 2 is a flow chart showing a preparatory processing procedure for determining whether there is an abnormality in the servo motor mechanism in the control system 100. As shown in FIG. FIG. 3 is a graph showing the relationship between the temperature variable and the temperature for calculating the offset amount C of the torque value. FIG. 4 is a graph showing the relationship between the pause period variable for calculating the offset amount C and the pause time. FIG. 5 is a graph showing the relationship between the operation frequency variable and the operation frequency for calculating the offset amount C. As shown in FIG. FIG. 6 is a graph showing changes in the offset amount with respect to the number of operations during the break-in period.

As shown in FIG. 2, in the PLC 1, the data acquisition unit 13 acquires the torque value from the servo driver 2 and acquires the temperature of the servo motor 31 from the temperature sensor 4 during normal operation (step S1).

The data correction unit 14 creates a reference curve based on the acquired torque value and temperature (step S2). The data correction unit 14 plots the torque value corresponding to the temperature in creating the reference curve (for example, the reference curve R shown in (a) of FIG. 8).

Next, the data correction unit 14 sets a threshold for the reference curve (step S3). In setting the threshold values, the data correction unit 14 sets an upper threshold value and a lower threshold value that define the normal value range of the torque value based on each value on the reference curve (for example, (a ) threshold TH (upper limit) and threshold TL (lower limit) shown in ).

Furthermore, the data correction unit 14 creates a calculation formula for calculating the offset amount C immediately after the start of the break-in (step S4). The data correction unit 14 expresses the equation as a function of three variables, temperature variable f _Temp , pause time variable f _Time , and operation count variable α, as follows.

C=f( _fTemp , _fTime , α)
=α* _fTemp * _fTime
Here, the offset amount C need not be calculated using all of the above three variables, and at least one variable may be used as necessary. For variables that are not used for calculating the offset amount C, the values of the variables are set to "1" in the formula.

Since the torque value is large at low temperatures and small at high temperatures, the temperature variable f _Temp is represented by a curve that is large at low temperatures and small at high temperatures, as shown in FIG. In addition, the torque value decreases as the pause time becomes shorter, and approaches a constant value as the pause _time becomes longer. Therefore, as shown in FIG. approximately constant value). Since the torque value decreases as the number of operations increases, as shown in FIG. It is represented by a curve that abruptly decreases to 0 and reaches almost 0 when the number of operations is 10 times.

When the offset amount C calculated using all three variables in the above calculation formula is expressed as a curve against the number of times of operation as shown in FIG. . When the temperature is low and the pause time is long, as indicated by the solid line in FIG. 6, the offset amount C takes a large value when the number of operations is one, and has a steeply decreasing slope when the number of operations is small. represented by a sharp curve. On the other hand, when the temperature is low and the pause time is long, the offset amount C takes a small value when the number of operations is one, as indicated by the dashed line in FIG. After that, it is represented by a gentle curve with a small amount of change.

Next, processing after restarting after the idle period of the servomotor mechanism 3 has ended will be described.

FIG. 7 is a flowchart showing a processing procedure for abnormality detection during pre-running. FIG. 8 is a side view showing a ball screw drive stage, which is an example of a machine tool showing data necessary for the processing shown in FIG. (a) to (c) of FIG. 9 are diagrams showing offset correction of the torque value by the control system. FIG. 10 is a diagram for explaining calculation of a torque correction value based on an offset with respect to a reference curve showing temperature change of a torque value.

During the pause period, the pause time measurement unit 111 measures the pause time and stores it in the memory 12 . In addition, during the break-in period that follows after the pause time ends and the operation of the servomotor mechanism 3 resumes, the operation number counting unit 112 counts the number of operations of the servomotor mechanism 3 .

As shown in FIG. 7, when the servomotor mechanism 3 is activated, the data acquisition unit 13 in the PLC 1 acquires the pause time from the memory 12 (step S11). Further, the data acquisition unit 13 acquires the torque value from the servo driver 2 and acquires the temperature of the servo motor 31 from the temperature sensor 4 in synchronization with acquiring the number of operations from the operation number counting unit 112 (step S12).

Here, it is assumed that the machine tool 32 of the servomotor mechanism 3 is a ball screw driven stage including a ball screw 51 and a stage 52 driven by the ball screw 51, as shown in FIG. When the stage 52 is moving from point P1 (predetermined point) to point P2 (predetermined point) to point P3, the data acquisition unit 13 Get the torque value and temperature of

Next, the data correction unit 14 calculates the offset amount X of the acquired torque value with respect to the reference value of the torque value corresponding to the acquired temperature on the reference curve created in advance as described above (step S13 ). The data correction unit 14 also calculates the offset amount C based on the above-described calculation formula using the acquired torque value and temperature (step S14).

As shown in (a) of FIG. 9, during the break-in period T, when the temperature is high, the offset amount C is calculated to be small, and as shown in (b) and (b) of FIG. 9, the temperature decreases. The offset amount C increases as the value increases. Further, as shown in (a) to (c) of FIG. 9, the reference curve R changes to reference curves R1 to R3 according to the offset amount C, and the threshold value R changes according to the change in the reference curve R. TH1 to TH3 and thresholds TL1 to TL3, respectively.

After that, the data correction unit 14 calculates a correction value D of the torque value by subtracting the offset amount C of the same temperature from the acquired temperature offset amount X, as shown in FIG. 10 (step S15). Further, the data correction unit 14 increases the threshold to a value obtained by adding the value of the offset amount C (threshold correction step).

Then, the abnormality detection unit 15 determines whether or not the calculated correction value exceeds the threshold (step S16, abnormality detection step). If the abnormality detection unit 15 determines in step S16 that the correction value exceeds the threshold (YES), it notifies that an abnormality has occurred (step S17), and returns the process to step S12. Further, when the abnormality detection unit 15 determines in step S16 that the correction value does not exceed the threshold value (NO), the process returns to step S12.

By repeating such processing for each number of times of operation, as shown in FIG. It is determined whether it is in the normal range between. As a result, even if the torque value increases in accordance with at least one of the temperature, rest time, and number of operations during the break-in period, the torque value is corrected based on the pre-calculated offset amount C. , it is possible to properly determine the abnormality detection of the torque value. Therefore, it becomes possible to suppress erroneous detection.

In step S12, it is preferable to use an average torque value when the stage 52 moves from the point P1 to the point P2. When the offset amount C is calculated using the maximum value of the torque, if abnormality detection is determined based on the correction value calculated by the offset amount C, there is a risk that the abnormality may be overlooked if the abnormality is local. On the other hand, by using the average of the torque values, it is possible to detect abnormal locations in a wide range.

Moreover, the information processing apparatus according to the present invention is not limited to the PLC 1, and may be a server. When configured in this way, the data acquisition unit 13 may acquire the pause time and the number of operations from a separately provided PLC.

[Example of realization by software]
The control blocks of the PLC 1 (especially the control unit 11, the data acquisition unit 13, the data correction unit 14, and the abnormality detection unit 15) may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like. Alternatively, it may be realized by software using a CPU (Central Processing Unit).

In the latter case, the PLC 1 includes a CPU that executes instructions of a control program, which is software that implements the functions of each unit, and a ROM (Read Only Memory) or storage device (these is referred to as a "recording medium"), a RAM (Random Access Memory) for developing the above program, and the like. The object of the present invention is achieved by the CPU reading the program from the recording medium and executing it.

As the recording medium, a "non-temporary tangible medium" such as a tape, disk, card, semiconductor memory, programmable logic circuit, or the like can be used. Also, the program may be supplied to the computer via any transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program.

It should be noted that the present invention can also be implemented in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention.

1 PLC
3 Servo motor mechanism (driving mechanism)
4 temperature sensor 14 data correction unit (threshold correction unit)
15 Abnormality detector 31 Servo motor (motor)
32 machine tools (driven equipment)

Claims (4)

an abnormality detection unit that detects an abnormality occurring in the operation of a drive mechanism having a driven device and a motor that drives the driven device when a torque value of the motor exceeds a threshold;
a threshold value correction unit that corrects the threshold value so that the threshold value used in a predetermined period after the drive mechanism resumes operation after a rest period is larger than during normal operation;
The information processing device, wherein the threshold correction unit corrects the threshold based on the number of operations of the drive mechanism during the predetermined period. 2. The information processing apparatus according to claim 1 , wherein the abnormality detection unit determines abnormality detection using an average of the torque values when the driven device moves between two predetermined points. 3. An information processing program for causing a computer to function as the information processing apparatus according to claim 1 or 2 , the information processing program for causing the computer to function as the abnormality detection unit and the threshold value correction unit. an abnormality detection step of detecting an abnormality occurring in the operation of a driving mechanism having a driven device and a motor for driving the driven device when a torque value of the motor exceeds a threshold value;
a threshold value correction step of correcting the threshold value so that the threshold value used in a predetermined period after the drive mechanism resumes operation after a rest period is larger than during normal operation;
The information processing method, wherein in the threshold value correction step, the threshold value is corrected based on the number of operations of the drive mechanism during the predetermined period.

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