TWI817402B - Diagnostic system for failure of motor encoder, and diagnostic method for using the same - Google Patents

Abstract

A diagnostic system for failure of motor encoder is disclosed and includes a motor, an encoder, a servo driver, and a safety module, wherein the servo driver controls the motor through a current command. The safety module continuously obtains a feedback position of the motor through the encoder. When the safety module determines based on the feedback positions that the current status of the motor complies with a pre-determined disturbance condition, the safety module requests the servo driver to send an external current command to disturb the motor. Next, the safety module determines whether the encoder is failure based on a variation of a next feedback position being obtained.

Description

Fault diagnosis system and fault diagnosis method for motor encoder

The present invention relates to a motor encoder, and in particular, to an encoder fault diagnosis system and fault diagnosis method.

When the motor rotates, the servo driver (servo) can read the motor's encoder to obtain motor data (such as rotation angle), thereby obtaining the motor's feedback position. Moreover, the servo driver can control the position of the motor based on the feedback position.

However, when the feedback position indicates that the position of the motor is fixed (i.e., the feedback position has not changed), the servo driver cannot distinguish whether the motor does not rotate so the feedback position does not change, or whether the motor rotates but the encoder fails and causes feedback The location has not changed. In this case, the servo drive cannot control the motor correctly.

As mentioned above, in order to prevent the system from not detecting the abnormality of the encoder and causing the motor to run out of control and cause danger, the present invention proposes a fault diagnosis mechanism suitable for the encoder.

The invention provides a fault diagnosis system and a fault diagnosis method for a motor encoder, which can diagnose whether the encoder is faulty when the position of the motor is fixed.

In one embodiment of the present invention, a motor encoder fault diagnosis system includes: a motor with an encoder that generates corresponding position information based on the rotation of the motor; a servo driver connected to the motor; and A safety module connects the encoder and the servo driver, reads the position information to obtain a feedback position of the motor, and determines whether the status of the motor meets a disturbance condition or a warning condition based on the feedback position; Wherein, the safety module is configured to request the servo driver to send an additional current command to the motor when it is determined that the state of the motor meets the disturbance condition; When a warning condition occurs, the servo drive is requested to send an abnormal warning signal.

In one embodiment of the present invention, a fault diagnosis method for a motor encoder includes the following steps: a) reading an encoder of a motor to obtain a feedback position of the motor; b) judging the motor based on the feedback position Whether the status of the motor meets a disturbance condition or a warning condition; c) when the status of the motor meets the disturbance condition, request a servo driver to issue an additional current command to the motor; and d) When the status of the motor meets the warning condition, request the servo driver to send an abnormal warning signal.

The present invention disturbs the motor when the feedback position provided by the encoder indicates that the position of the motor is fixed. Compared with the related art, the present invention uses the feedback position after the disturbance to determine whether the motor is indeed not rotating, or whether the motor is rotating but the encoder is faulty and provides a wrong feedback position.

1: Motor

2: Encoder

3:Servo drive

4: Security module

5: Current command

6: Extra current command

S10~S22, S30~S48, S50~S68: Diagnosis steps

S70~S88: Disturbance step

Figure 1 is a block diagram of a fault diagnosis system according to a first specific embodiment of the present invention.

Figure 2 is a first specific embodiment of the flow chart of the fault diagnosis method of the present invention.

Figure 3 is a second specific embodiment of the flow chart of the fault diagnosis method of the present invention.

Figure 4 is a third specific embodiment of the flow chart of the fault diagnosis method of the present invention.

Figure 5 is a first specific embodiment of the perturbation flow chart of the present invention.

Figure 6 is a first specific embodiment of a schematic diagram of a disturbance wave pattern of the present invention.

Figure 7 is a second specific embodiment of a schematic diagram of a disturbance wave pattern of the present invention.

A preferred embodiment of the present invention is described in detail below with reference to the drawings.

First, please refer to FIG. 1 , which is a block diagram of a fault diagnosis system according to a first specific embodiment of the present invention. The present invention discloses a fault diagnosis system for a motor encoder (hereinafter referred to as the diagnosis system in the description). As shown in Figure 1 , the diagnosis system mainly includes a motor 1, an encoder 2 and a servo driver 3.

Encoder 2 can be installed on the shaft of motor 1. When the motor 1 rotates, the encoder 2 generates corresponding motor data according to the rotation of the motor 1 , where the motor data at least includes position information of the motor 1 . When there is a connection relationship between the servo driver 3 and the encoder 2 , the servo driver 3 can read the motor data output by the encoder 2 and thereby obtain the feedback position of the motor 1 . Specifically, the servo driver 3 mainly reads the position information in the motor data, thereby obtaining the feedback position of the motor 1 through the position information. Through the feedback position, the servo driver 3 can determine the current rotation status of the motor 1 and then control the position of the motor 1 .

In the embodiment of FIG. 1 , the servo driver 3 and the motor 1 are directly connected through lines. In this embodiment, the servo driver 3 generates a corresponding current command (lq) 5 based on the feedback position, and sends the current command 5 to the motor 1 to control the position of the motor 1 .

In the present invention, the diagnostic system further includes a safety module 4, which is connected to the encoder 2 and the servo driver 3. In one embodiment, the security module 4 is implemented in software or firmware, and is recorded in a hardware unit independent of the servo driver 3 . In another embodiment, the security module 4 is implemented in software or firmware and recorded in the encoder 2, but this is not a limitation.

The safety module 4 can continuously read the position information generated by the encoder 2 to obtain the feedback position of the motor 1. The feedback position is a commonly used technology in this technical field. The means will not be described again here. One of the technical features of the present invention is that the safety module 4 can monitor and determine the status of the motor 1 based on the feedback position, and determine whether the status of the motor 1 meets the preset disturbance conditions (described in detail later).

In the present invention, the state of the motor 1 refers to the stagnant state of the motor 1 , that is, the state in which the motor 1 is not rotating.

In the related art, the servo driver 3 mainly obtains the current status of the motor 1 (such as whether it is rotating or not) through feedback position. If the feedback position indicates that the position of motor 1 has not changed, the servo driver 3 will determine that the position of motor 1 is fixed. However, in the related art, the servo driver 3 cannot directly distinguish through the feedback position whether the motor 1 is really not rotating or whether the feedback position is incorrect due to an abnormality of the encoder 2 .

The present invention solves the above problems through the installation of the security module 4 . Specifically, the safety module 4 replaces the servo driver 3 to obtain the feedback position of the motor 1 from the encoder 2 to determine the status of the motor 1 . When the safety module 4 determines that the status of the motor 1 meets the preset disturbance conditions based on the feedback position (for example, the motor 1 has not rotated for a certain period of time), it will cooperate with the servo driver 3 to perform a confirmation action to determine that the motor 1 is indeed not rotating. rotation, or encoder 2 is malfunctioning.

Specifically, when the safety module 4 determines that the state of the motor 1 meets the disturbance condition, it will request the servo driver 3 to send an additional current command (elq) 6 to the motor 1 . If encoder 2 is normal, when motor 1 is affected by the extra current command 6 and shakes, the motor data generated by encoder 2 will inevitably change (at least the position information in the motor data will change), and then safety module 4 The feedback position obtained will definitely indicate the position change of motor 1. In this case, the security module 4 can determine that the encoder 2 operates normally.

If after the servo driver 3 sends the extra current command 6 to the motor 1, the safety module 4 still determines that the position of the motor 1 is fixed based on the subsequently obtained feedback position, then the safety module 4 can determine that an abnormality occurs in the encoder 2.

However, the above are only some specific implementation examples of the present invention, but are not limited thereto.

In one embodiment, the safety module 4 continuously obtains the feedback position of the motor 1, and determines whether the position of the motor 1 is fixed based on the continuously obtained feedback position. If the position of motor 1 is fixed, but the fixed time does not reach the preset first time length (such as 200ms, 300ms, etc.), the safety module 4 does not take any action and continues to monitor the status of motor 1.

If the position of the motor 1 is fixed and the fixed time reaches the first time length, the safety module 4 can determine that the state of the motor 1 meets the disturbance condition. At this time, the safety module 4 will request the servo driver 3 to send an additional current command 6 to the motor 1 to disturb the motor 1.

However, the above are only some specific implementation examples of the present invention, but are not limited thereto.

It is worth mentioning that in addition to the above disturbance conditions, the safety module 4 can also determine whether the status of the motor 1 meets the preset warning conditions based on the feedback position (for example, the motor 1 does not rotate for longer than the disturbance condition requires. length of time). When the status of motor 1 meets the warning conditions, safety module 4 can directly determine that encoder 2 has failed. In this case, the safety module 4 can request the servo driver 3 to send an abnormal warning signal to remind the user to inspect the encoder 2 .

In one embodiment, the safety module 4 continuously obtains the feedback position of the motor 1 and continuously determines whether the position of the motor 1 is fixed. If the position of the motor 1 is fixed, but the fixed time does not reach the preset second time length, the safety module 4 does not take any action and continues to monitor the status of the motor 1. If the position of the motor 1 is fixed and the fixed time reaches the second time length, the safety module 4 can determine that the state of the motor 1 meets the warning condition. At this time, the security module 4 can request the servo driver 3 to send an abnormality warning signal.

In one embodiment of the present invention, the second time length is greater than the first time length. For example, the second time length can be 500ms, 600ms, etc., but is not limited thereto.

In one embodiment, when the safety module 4 determines that the status of the motor 1 meets the warning condition, it can send a control command to the servo driver 3 . Thereby, the servo driver 3 displays an abnormality warning signal on the driver panel (not shown in the figure) based on the control command, or plays the abnormality warning signal through a buzzer (not shown in the figure), but is not limited to this.

Please also refer to FIG. 2 , which is a first specific embodiment of a flow chart of the fault diagnosis method of the present invention. The present invention further discloses a fault diagnosis method for a motor encoder (hereinafter referred to as the diagnosis method in the description). The diagnosis method is mainly applied to the diagnosis system as shown in Figure 1, but is not limited thereto.

As mentioned above, the security module 4 of the present invention is mainly implemented by software or firmware. When the processor (such as the encoder 2 or other hardware unit independent of the servo driver 3) executes the software or firmware, After integration, the security module 4 can be virtually established to implement each execution step of the diagnostic method of the present invention.

As shown in Figure 2, to use the diagnostic method of the present invention, first, the motor 1 needs to enter the position mode (step S10), and the safety module 4 reads the corresponding position information from the encoder 2 of the motor 1. This obtains the feedback position of the motor (step S12).

Specifically, the motor 1 usually becomes stationary only when it is being positioned. At this time, although the feedback position indicates that the motor 1 is stationary, the safety module 4 cannot know whether the motor 1 is indeed not rotating, or whether the encoder 2 is faulty and produces an erroneous feedback position. Therefore, the diagnostic method of the present invention is mainly used to diagnose faults of the encoder 2 in the position mode of the motor 1 .

Generally speaking, motor 1 also has other control modes such as speed mode and torque mode. However, in speed mode and torque mode, motor 1 is usually controlled and continues to rotate. At this time, if the feedback position indicates that the motor 1 is stationary, the safety module 4 can directly infer that the encoder 2 is faulty, without the need to diagnose the encoder 2 through the diagnostic system and diagnostic method of the present invention.

However, the above is one of the specific implementation examples of the present invention, but it is not limited thereto.

After step S12, the safety module 4 determines the status of the motor 1 based on the feedback position, and determines whether the status of the motor 1 meets the preset disturbance conditions (step S14). If the status of the motor 1 meets the disturbance condition, the safety module 4 can send a corresponding control command to the servo driver 3 to request the servo driver 3 to send an additional current command 6 to the motor 1 (step S16). If the status of motor 1 does not meet the disturbance conditions, safety module 4 will not act.

Furthermore, the security module 4 simultaneously determines whether the status of the motor 1 meets the preset warning conditions (step S18). If the status of motor 1 meets the warning conditions, safety module 4 A corresponding control command can be sent to the servo driver 3 to request the servo driver 3 to send an abnormality warning signal to the outside (step S20). If the status of motor 1 does not meet the warning conditions, safety module 4 will not operate.

Furthermore, when executing the diagnostic method of the present invention, the security module 4 continues to determine whether the detection operation of the motor 1 and/or the encoder 2 is completed (step S22). Before the detection of the motor 1 and/or the encoder 2 ends, the safety module 4 repeatedly executes steps S12 to S20, thereby continuously obtaining the feedback position of the motor 1, continuing to determine the status of the motor 1, and When the specified conditions are met, the servo driver 3 is requested to issue an additional current command 6 and an abnormal warning signal.

As mentioned above, the safety module 4 in the present invention mainly determines the status of the motor 1 based on the continuously obtained feedback position, and when it determines that the position of the motor 1 is fixed and the fixed time reaches the preset time length, it is determined that the motor 1 meets the requirements. Disturbance conditions (that is, it is necessary to disturb motor 1 to confirm whether encoder 2 is abnormal), or meet warning conditions (that is, it is confirmed that encoder 2 is abnormal and a warning needs to be issued to the outside). The disturbance conditions and warning conditions will be described respectively using different embodiments below.

Please continue to refer to FIGS. 1 to 3 , where FIG. 3 is a second specific embodiment of the flow chart of the fault diagnosis method of the present invention. The disturbance conditions will be described below based on the embodiment of FIG. 3 .

First, the safety module 4 continues to obtain the feedback position of the motor 1 during system operation (step S30). Then, the security module 4 compares the feedback position obtained in step S30 with the temporarily stored previous feedback position (step S32), and based on whether the previous and last two feedback positions are the same, it determines whether the motor 1 Is the position fixed (step S34).

If it is determined in step S34 that the position of the motor 1 is fixed, the safety module 4 controls an internal counter (not shown) to count (step S36).

In one embodiment, the safety module 4 is fixed to obtain a feedback position in each cycle and determine the position of the motor 1, and controls the counter to increase by one when it is determined that the position of the motor 1 is fixed. In this embodiment, the counting content of the counter is equivalent to the execution cycle of the security module 4 .

In another embodiment, the safety module 4 obtains the feedback position and determines the position of the motor 1 based on a fixed time length (for example, 1 ms), and controls the counter to increase by one when it is determined that the position of the motor 1 is fixed. In this embodiment, the count content of the counter is equivalent to the actual length of time.

For the convenience of explanation, the following explanation will be based on the example that the counting content of the counter is equivalent to the actual length of time.

If it is determined in step S34 that the position of the motor 1 is fixed, the safety module 4 then determines whether the count of the counter reaches the preset first time length (step S38). That is to say, the safety module 4 determines whether the motor 1 maintains a fixed time duration and reaches the first time length based on the counting status of the counter, such as 20 ms, 30 ms, etc., but it is not limited.

If it is determined in step S38 that the count of the counter reaches the first time length, the security module 4 may determine that the motor 1 meets the disturbance condition. In the present invention, when the safety module 4 determines that the motor 1 meets the disturbance conditions, it requests the servo driver 3 to send the additional current command 6 to the motor 1 .

In one embodiment, when the safety module 4 determines that the motor 1 meets the disturbance condition, it sends a control command to the servo driver 3, thereby setting a disturbance flag (not shown) in the servo driver 3 to enabled (step S40 ). When the servo driver 3 finds that the internal disturbance flag is set to enabled, it will automatically send an additional current command 6 to the motor 1 to disturb the motor 1. If motor 1 operates normally, after receiving the additional current command 6 sent by servo driver 3, motor 1 will shake, causing its position to change slightly.

If it is determined in step S38 that the count of the counter has not reached the first length of time, the security module 4 does not perform any action temporarily.

Next, the security module 4 determines whether the detection operation for the motor 1 and/or the encoder 2 is completed (step S42). If the detection operation of the motor 1 and/or the encoder 2 has not yet ended, the safety module 4 will temporarily stay in the feedback position obtained in step S30 (step S44), and return to step S30. In the next cycle, the safety module 4 obtains the next feedback position of the motor 1 and compares it with the temporarily stored previous feedback position to determine whether the position of the motor 1 is fixed.

The above describes the action when the safety module 4 determines that the position of the motor 1 is fixed. If it is determined in step S34 that the position of the motor 1 has changed, it means that the encoder 2 is operating normally. At this time, the safety module 4 does not need to disturb the motor 1 to test the encoder 2. In this case, the security module 4 resets the counter to zero (step S46). Furthermore, the security module 4 can selectively send a control command to the servo driver 3 to set the disturbance flag of the servo driver 3 to be disabled (step S48). In the present invention, the diagnostic system can use the security module 4 to The moving flag is set to be disabled, or the disturbance flag is set to be disabled by the servo driver 3 (described in detail later), which is not limited.

When the servo driver 3 finds that the disturbance flag is set to be disabled, it will not modify the current command 5 and the additional current command 6 currently sent to the motor 1. Therefore, the motor 1 will not be affected by the servo driver 3 and cause vibration.

Please continue to refer to FIGS. 1 to 4 , where FIG. 4 is a third specific embodiment of the flow chart of the fault diagnosis method of the present invention. The warning conditions will be described below based on the embodiment of FIG. 4 .

Specifically, the embodiment of FIG. 4 and the embodiment of FIG. 3 can be executed in the same cycle, that is, each step in FIG. 3 and each step in FIG. 4 can be executed simultaneously. In order to facilitate understanding, each step of Figure 4 will be described independently below.

As shown in Figure 4, the safety module 4 continues to obtain the feedback position of the motor 1 (step S50), and compares the obtained feedback position with the temporarily stored previous feedback position (step S52). It is determined whether the position of the motor 1 is fixed (step S54).

If it is determined in step S54 that the position of the motor 1 is fixed, the safety module 4 controls the counter to count (step S56). Furthermore, the security module 4 determines whether the count of the counter reaches a preset second time length (step S58), that is, the security module 4 determines whether the time in which the position of the motor 1 is fixed continues and reaches the second time length.

If the count of the counter reaches the second time length, the security module 4 can send a control command to the servo driver 3 to set a warning flag (not shown) in the servo driver 3 to enabled (step S60). When the servo driver 3 finds that the internal warning flag is set to enabled, it will automatically send an abnormal warning signal to the outside.

If it is determined in step S58 that the count of the counter has not reached the second time length, the security module 4 does not perform any action. It is worth mentioning that the embodiment of FIG. 3 and the embodiment of FIG. 4 use the same counter. If the count of the counter has reached the first time length but has not reached the second time length, the safety module 4 will still request the servo driver 3 to send the additional current command 6 to the motor 1 at this time.

In one embodiment, the second time length is greater than the first time length in the embodiment of FIG. 3 . For example, the second time length may be 50 ms, 60 ms, etc., but is not limited thereto.

The following describes the embodiment by taking the first time length as 20 ms and the second time length as 50 ms as an example. In this embodiment, the safety module 4 continues to determine whether the position of the motor 1 is fixed by comparing the previous and subsequent feedback positions. When it is determined that the position of motor 1 is fixed and the fixed time reaches 20ms (that is, the counter counts for 20ms), the safety module 4 enables the disturbance flag to cause the servo driver 3 to send an additional current command 6 to the motor 1.

If the position of motor 1 is still fixed after servo driver 3 sends additional current command 6, the counter continues to count (that is, the counter accumulates 21ms, 22ms, and so on).

When the safety module 4 determines that the position of the motor 1 is fixed and the counter reaches 40ms (that is, the second accumulation of 20ms), the disturbance flag will be set again to cause the servo driver 3 to cancel the additional current currently sent to the motor 1 Command 6 to perturb motor 1 again (detailed later).

If the position of motor 1 is still fixed after servo driver 3 cancels extra current command 6, the counter will continue to count (that is, the counter will accumulate 41ms, 42ms, and so on).

When the safety module 4 determines that the position of the motor 1 is fixed and the counter reaches 50ms, it will enable the warning flag, thereby causing the servo driver 3 to send an abnormal warning signal to the outside. When the servo driver 3 sends an abnormality warning signal, the user can know that an abnormality has occurred in the motor 1 or the encoder 2 and perform maintenance.

However, the above is only a specific implementation example of the present invention, and the counting method, first time length, and second time length of the counter in the present invention are not limited to the above.

Back to Figure 4. In the embodiment of FIG. 4 , the security module 4 will also continue to determine whether the detection operation of the motor 1 and/or the encoder 2 is completed (step S62 ). If the detection operation of the motor 1 and/or the encoder 2 has not yet ended, the safety module 4 will temporarily stay in the feedback position obtained in step S50 (step S64), and return to step S50. In the next cycle, the safety module 4 obtains the next feedback position of the motor 1 and compares it with the temporarily stored previous feedback position to determine whether the position of the motor 1 is fixed.

Similar to the embodiment of FIG. 3 , if it is determined in step S54 that the position of the motor 1 has changed, it means that the safety module 4 does not need to disturb the motor 1 to test the encoder 2 . Therefore, the security module 4 resets the counter to zero (step S66). Furthermore, the security module 4 can selectively send a control command to the servo driver 3 to set the warning flag of the servo driver 3 to be disabled (step S68). When servo drive 3 finds that the warning flag is set to disabled , abnormal warning signals will no longer be sent to the outside world. Accordingly, the user can know that the motor 1 and the encoder 2 have resumed normal operation.

One of the technical features of the present invention is to add a safety module 4 to the diagnostic system, and modify the servo driver 3 to add the disturbance flag and the warning flag. The diagnostic system of the present invention monitors the position status of the motor 1 through the safety module 4, and the safety module 4 sets the disturbance flag and warning flag of the servo driver 3 based on the position status. Thereby, the servo driver 3 can refer to the content of the disturbance flag (ie, enable or disable) to determine whether it is necessary to issue/cancel the additional current command 6, and refer to the content of the warning flag (ie, enable or disable), To determine whether it is necessary to issue an abnormal warning signal to the outside world.

Please continue to refer to Figures 1 to 5, where Figure 5 is a first specific embodiment of the perturbation flow chart of the present invention. The operation of the servo driver 3 will be described below based on the embodiment of FIG. 5 .

As shown in Figure 5, the servo driver 3 will continue to determine whether the internal disturbance flag is enabled (step S70). In one embodiment, if it is determined that the disturbance flag is enabled, the servo driver 3 will further determine whether it is currently in the position mode of the motor 1 (step S72).

As mentioned above, motor 1 is generally only possible to be stationary in position mode. In other words, the diagnostic system and diagnostic method of the present invention only need to disturb the motor 1 in the position mode of the motor 1 to confirm whether the encoder 2 is normal.

If the disturbance flag is enabled and the motor 1 is in the position mode, the safety module 4 further reads the internal additional current command state and determines whether the current additional current command state is the first value or the second value (step S74). In one embodiment, the first numerical value and the second numerical value are different (for example, the first numerical value is 0 and the second numerical value is 1), but this is not a limitation.

The present invention disturbs the motor 1 to change the position of the motor 1, and then diagnoses whether the encoder 2 is normal based on the content of the feedback position. When the servo driver 3 sends the extra current command 6 to the motor 1, the motor 1 will shake due to the influence, then gradually return to stability, and finally return to the original position. When the servo driver 3 wants to disturb the motor 1 next time, it must cancel the additional current command 6 currently sent (or send an additional current command 6 with a different value) before the motor 1 can shake again. In order to determine whether the extra current command 6 should be sent or cancel the currently sent extra current command 6 due to this disturbance, the present invention modifies the servo driver 3 so that the servo driver 3 records the extra current command status.

In one embodiment, if the additional current command status currently records a first value (for example, 0), it means that the servo driver 3 does not provide the additional current command 6 to the motor 1 . At this time, the servo driver 3 can send the preset additional current command 6 to the motor 1 (step S76), and set the additional current command state to the second value (step S78).

If it is determined in step S74 that the additional current command status currently records a second value (for example, 1), it means that the servo driver 3 currently continues to provide the additional current command 6 to the motor 1 . At this time, the servo driver 3 can cancel the extra current command 6 (step S80), and set the extra current command state to the first value (step S82).

In one embodiment, the additional current command 6 may be, for example, 5% of the rated current of the motor 1 . In addition, the action of the servo driver 3 to cancel the additional current command 6 in step S80 may be, for example, setting the additional current command 6 to 0% of the rated current of the motor 1 . However, the above is only one specific implementation example of the present invention, but it is not limited thereto.

Please refer to FIG. 6 and FIG. 7 at the same time. FIG. 6 is a first specific embodiment of a schematic diagram of a disturbance wave pattern of the present invention, and FIG. 7 is a second specific embodiment of a schematic diagram of a disturbance wave pattern of the present invention.

As shown in the embodiment of FIG. 6 , the feedback position of the motor 1 indicates that the position of the motor 1 is fixed, and the fixed time lasts for 20 ms (that is, it is fixed between 0 seconds and 0.2 seconds). At this time, the safety module 4 sends an additional current command 6 (Figure 6 takes 5% of the rated current as an example) to the motor 1. After receiving the additional current command 6, the motor 1 will shake in the first direction. As time passes, motor 1 stops shaking and returns to standstill when it is close to 0.4 seconds.

Next, as shown in the embodiment of FIG. 7 , the feedback position of the motor 1 indicates that the position of the motor 1 is fixed, and the fixed time lasts for 20 ms (that is, it is fixed between 0.4 seconds and 0.6 seconds). At this time, the safety module 4 cancels the currently sent additional current command 6 (Figure 7 takes the example of modifying 5% of the rated current to 0% of the rated current). After the motor 1 cannot receive the original additional current command 6, it will shake in the second direction opposite to the first direction. As time passes, motor 1 stops shaking and returns to standstill at close to 0.8 seconds.

As shown in the embodiments of Figures 6 and 7, if the encoder 2 operates normally, when the safety module 4 sends or cancels the additional current command 6, the position of the motor 1 will change. changes, and the feedback position obtained by Security Module 4 will indicate this change. In other words, if the feedback position does not indicate a position change as shown in Figures 6 and 7 after the safety module 4 sends or cancels the additional current command 6, the safety module 4 can infer that the encoder 2 may malfunction.

As mentioned above, the security module 4 will request the servo driver 3 to disturb the motor 1 multiple times before the warning flag of the servo driver 3 is enabled. Among them, when the servo driver 3 disturbs the motor 1 for the first time, it will send an additional current command 6 (for example, 5% of the rated current). When it disturbs the motor 1 for the second time, it will cancel the additional current command 6 (for example, 0% of the rated current). When motor 1 is disturbed three times, additional current command 6 will be sent again, and so on until the warning flag is enabled, safety module 4 stops detection, or other stop conditions are met.

Return to Figure 5. After issuing the extra current command 6 or canceling the extra current command 6 , the servo driver 3 actively sets the disturbance flag to be disabled (step S84 ). Thereby, the servo driver 3 will not change the state of the additional current command 6 temporarily.

Like the security module 4, the servo driver 3 will continue to determine whether the diagnostic method of the present invention ends (step S86), and repeatedly executes steps S70 to step S84 before the diagnostic method ends to send or cancel additional data based on the content of the disturbance flag. Current command 6.

In addition to the disturbance flag, the servo driver 3 will also continue to determine whether the internal warning flag is enabled (step S88). If the warning flag is enabled (for example, set to enabled by the security module 4 in step S60 of FIG. 4 ), the servo driver 3 sends an abnormality warning signal to the outside based on the content of the warning flag (step S90 ).

In one embodiment, the servo driver 3 can display an abnormality warning signal in the form of text, graphics, color or a combination thereof through the driver panel (not shown in the figure), or use a buzzer (not shown in the figure) to sound an abnormality warning signal. method to play abnormal warning signals, but is not limited to this. When the servo driver 3 sends an abnormal warning signal to the outside, the user can know that the motor 1 or the encoder 2 is faulty.

When the feedback position indicates that the position of the motor is fixed, the present invention uses the additional current command 6 to cause the motor 1 to shake. Compared with related technologies, the present invention does not need to set the position of the motor 1 or the threshold of the current command, and is applicable to various types of encoders (such as communication type or non-communication type), making the diagnosis of the encoder more convenient. For convenience.

The above descriptions are only preferred specific examples of the present invention, which do not limit the patent scope of the present invention. Therefore, all equivalent changes made by applying the content of the present invention are equally included in the scope of the present invention, and are hereby stated. bright.

1: Motor

2: Encoder

3:Servo drive

4: Security module

5: Current command

6: Extra current command

Claims (15)

A fault diagnosis system for a motor encoder, including: a motor with an encoder that generates corresponding position information based on the rotation of the motor; a servo driver connected to the motor; and a safety module connected to the motor. The encoder and the servo driver read the position information to obtain a feedback position of the motor, and determine whether the status of the motor meets a disturbance condition or a warning condition based on the feedback position; wherein, the safety module is Configured to request the servo driver to send an additional current command to the motor when it is determined that the state of the motor meets the disturbance condition, and the additional current command perturbs the motor to confirm whether the encoder is abnormal; wherein, the safety module is configured as When it is determined that the status of the motor meets the warning condition, the servo driver is requested to send an abnormal warning signal, and the encoder is determined to be abnormal through the abnormal warning signal. The fault diagnosis system as described in claim 1, wherein the safety module is configured to determine that the motor meets the disturbance condition when it is determined based on the feedback position that the position of the motor is fixed and the fixed time lasts for a first time length, And when it is determined based on the feedback position that the position of the motor is fixed and the fixed time lasts for a second time length, it is determined that the motor meets the warning condition, wherein the second time length is greater than the first time length. The fault diagnosis system of claim 2, wherein the servo driver has a disturbance flag and a warning flag, and the safety module is configured to set the disturbance flag to enable to enable the servo driver. The servo driver sends the extra current command to the motor, and sets the warning flag to enable so that the servo driver issues the abnormal warning signal. The fault diagnosis system of claim 3, wherein the safety module is configured to set the disturbance flag and the warning flag to be disabled when determining the position change of the motor based on the feedback position. The fault diagnosis system as described in claim 3, wherein the servo driver has an extra current command state, and the servo driver is configured to read the extra current command state when the disturbance flag is enabled, and when the extra current command The additional current command is sent when the status is a first value, and the additional current command is canceled when the additional current command status is a second value. The fault diagnosis system of claim 5, wherein the servo driver is configured to set the additional current command state to the second value after sending the additional current command, and to set the additional current command after canceling the additional current command. The status is the first value. The fault diagnosis system of claim 5, wherein the servo driver is configured to set the disturbance flag to disabled after sending the extra current command or canceling the extra current command. The fault diagnosis system as described in any one of claims 1-7, wherein the additional current command is 5% of a rated current. A fault diagnosis method for a motor encoder, including: a) reading an encoder of a motor to obtain a feedback position of the motor; b) judging whether the status of the motor meets a disturbance condition or a feedback position based on the feedback position Warning condition; c) When the status of the motor meets the disturbance condition, request a servo driver to issue an additional current command to the motor, wherein the additional current command disturbs the motor to confirm whether the encoder is abnormal; and d) When the status of the motor meets the warning condition, request the servo driver to send an abnormal warning signal, and determine that the encoder is abnormal through the abnormal warning signal. The fault diagnosis method as described in claim 9, wherein step b) includes: b11) comparing the feedback position with the previous feedback position to determine whether the position of the motor is fixed; b12) determining whether the position of the motor is fixed; When the position of the motor is fixed, a counter is controlled to count; and b13) when the count of the counter reaches a first length of time, it is determined that the motor meets the disturbance condition. The fault diagnosis method as described in claim 10, wherein the step b) further includes a step b14): when the counter reaches a second length of time, it is determined that the motor meets the warning condition, wherein the second length of time is greater than the first length of time. The fault diagnosis method as described in claim 10, wherein step c) includes: when the motor meets the disturbance condition, setting a disturbance flag in the servo driver to enable, whereby the servo driver based on the disturbance The flag sends the extra current command to the motor, and the step d) includes: when the motor meets the warning condition, setting a warning flag in the servo driver to enable, whereby the servo driver based on the warning The flag issues a warning signal for the abnormality. The fault diagnosis method as described in claim 12, which further includes: e) when it is determined that the position of the motor has changed, controlling the counter to return to zero; and f) when it is determined that the position of the motor has changed, setting the disturbance flag and This warning flag is set to disabled. The fault diagnosis method as described in claim 12, further comprising: g) the servo driver reads an extra current command status when the disturbance flag is enabled; h) Send the additional current command when the additional current command state is a first value, and set the additional current command state to a second value; i) Cancel the additional current command when the additional current command state is the second value current command, and set the additional current command state to the first value; and j) after step h) or step i), set the disturbance flag to be disabled. The fault diagnosis method as described in claim 14, wherein the step g) includes: g1) the servo driver determines whether the motor operates in a position mode when the disturbance flag is enabled; and g2) when the motor operates Read the additional current command status in this position mode.

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