TWI705657B - Motor control device - Google Patents

Abstract

A motor control device includes: a compensation data storage unit in which data corresponding to changes in torque of a motor due to cogging torque is stored; and a disturbance observer configured to calculate a cogging torque estimated value in accordance with the position of the motor to make disturbance suppression compensation on the basis of the calculated cogging torque estimated value. This can prevent the influence of friction and the like and reduce speed ripple and torque ripple of the motor.

Description

Motor control device

The present invention relates to a motor control device for estimating and suppressing motor disturbance.

In machine tools, high processing quality is pursued due to the requirements of micro-fabrication. For this reason, the high precision of motor drive is pursued. Moreover, in order to shorten the cycle time (cycle time), it is sought to shorten the positioning time.

On the other hand, miniaturization of motors is also pursued. In the case of a miniaturized motor, the backlash torque may increase due to the limitation of the structure of the motor. The torque ripple due to such backlash torque becomes an external disturbance and acts during work processing. The torque ripple caused by the backlash torque will reduce the surface accuracy of the workpiece, or it will act as an external disturbance during positioning, resulting in a change in position deviation. This change in position deviation is due to the delay in positioning time, which unfortunately causes the mechanical cycle time to become longer. Moreover, in mechanical systems, there is friction. This kind of friction becomes a factor that reduces the machining accuracy or delays positioning.

Fig. 5 is a configuration diagram of a conventional disturbance observer for suppressing such external disturbance. In the conventional disturbance observer, a low-pass filter is used to estimate the load torque based on the torque command and the motor speed. However, the insertion of a low-pass filter for noise removal due to differential calculation causes attenuation and phase deviation of the estimated value. For this reason, it is difficult to properly compensate the torque ripple.

An example of high response of such an external disturbance observer is described in Japanese Patent Laid-Open No. 4-69082. The servo motor control device described in Japanese Patent Application Laid-Open No. 4-69082 includes an observer for estimating the external disturbance torque and a correction means for correcting the torque command (torque command) using the estimated external disturbance torque. In the above-mentioned observer, the premise is that the external disturbance torque that is constant in time is given to the servo motor through a low-pass filter. The above-mentioned correction means uses the estimated external disturbance torque obtained by the above-mentioned observer to correct the torque command.

Here, in actual encoders, there are quantization errors due to the limitation of resolution. For this reason, the method disclosed in Japanese Patent Laid-Open No. 4-69082 has the following problems. That is, the gain of the high pass of the external disturbance torque estimated by the observer is increased. For this reason, the ripple caused by the quantization error of the encoder appears in the estimated external disturbance torque. In particular, when the resolution of the encoder is low, it is a pity that the noise of the external disturbance torque is estimated to increase.

The present invention was invented in view of the above-mentioned circumstances. The object of the present invention is to provide the following motor control device. In this motor control device, while suppressing the influence of the quantization error of the encoder, the external disturbance torque including the backlash torque of the motor is estimated to perform external disturbance suppression compensation. Through this, the influence of friction can be suppressed, and the speed ripple and torque ripple of the motor can be reduced.

One aspect of the motor control device (this motor control device) of the present invention is provided with: a compensation data storage unit that stores data corresponding to the torque variation of the motor caused by the backlash torque; and an external disturbance observer, which is Calculate the estimated value of backlash torque corresponding to the position of the motor, and perform external disturbance suppression compensation based on the calculated estimated value of backlash torque.

According to this motor control device, it is possible to estimate the external disturbance torque including the backlash torque and torque ripple of the motor while suppressing the influence of the quantization error of the encoder. By using the external disturbance observer to perform external disturbance suppression compensation, the influence of friction and the like can be suppressed, and the speed ripple and torque ripple of the motor can be reduced.

1‧‧‧Motor control device

2‧‧‧Motor

3‧‧‧Encoder

4‧‧‧Speed Controller

5‧‧‧torque controller

10‧‧‧External Disturbance Observer

11‧‧‧Compensation data memory

12‧‧‧The first speed calculator

13‧‧‧Speed Calculator

14‧‧‧The first multiplier

15‧‧‧Low Pass Filter

16‧‧‧The second multiplier

100‧‧‧Backlash torque estimation value calculation unit

200‧‧‧First speed calculation unit

300‧‧‧Second speed calculation unit

400‧‧‧External disturbance torque estimation value calculation unit

500‧‧‧Total external disturbance torque calculation unit

Fig. 1 shows a motor control device according to an embodiment of the present invention An example of the composition.

Fig. 2 shows an example of the configuration of an external disturbance observer provided in the motor control device.

Fig. 3 shows an example of the configuration of a speed control system applied to the disturbance observer provided in the motor control device.

Figure 4 shows the simulation results of external disturbance suppression compensation.

Fig. 5 shows the structure of a conventional disturbance observer.

In the following detailed description, for explanatory purposes, many specific details are mentioned in order to provide an in-depth understanding of the disclosed implementation modes. However, it should be understood that one or more implementation aspects can be implemented without these specific details. In other different situations, well-known structures and devices are schematically shown to simplify the drawings.

As shown in FIG. 1, the motor control device 1 according to this embodiment includes a compensation data storage unit 11 and an external disturbance observer 10. The compensation data storage unit 11 stores the backlash torque data (backlash torque data) corresponding to the position of the motor 2 as the data for suppressing the torque fluctuation of the motor 2 caused by the backlash torque. With.

The disturbance observer 10 acquires the position of the motor 2. The disturbance observer 10 calculates the backlash torque estimation value from the acquired position of the motor based on the backlash torque data stored in the compensation data storage unit 11. Furthermore, the external disturbance observer 10 performs external disturbance suppression compensation based on the calculated backlash torque estimation value. Moreover, the motor control device 1 has: Speed controller 4, torque controller 5, and speed calculator 13. Regarding these, it will be described later using Figure 3.

The disturbance observer 10 includes a backlash torque estimation value calculation unit 100, a first speed calculation unit 200, a second speed calculation unit 300, an external disturbance torque estimation value calculation unit 400, and a total external disturbance torque calculation unit 500. The backlash torque estimation value calculation unit 100 calculates the backlash torque estimation value. The first speed calculation unit 200 uses a nominal inertia to calculate the first speed. The second speed calculation unit 300 calculates the second speed excluding the backlash torque estimation value. The estimated external disturbance torque value calculation unit 400 calculates the estimated disturbance torque excluding the estimated backlash torque. The total external disturbance torque calculation unit 500 calculates the total external disturbance torque.

The backlash torque estimation value calculation unit 100 has a compensation data storage unit 11. The backlash torque estimation value calculation unit 100 calculates the backlash torque estimation value based on the backlash torque data. That is, the backlash torque estimation value calculation unit 100 obtains the motor position detected by the encoder 3. The backlash torque estimation value calculation unit 100 calculates the backlash torque estimation value from the acquired motor position based on the backlash torque data stored in the compensation data storage unit 11. That is, the backlash torque estimation value calculation unit 100 calculates the backlash torque estimation value based on the backlash torque data and the motor position. The backlash torque estimation value calculation unit 100 outputs the calculated backlash torque estimation value to the first speed calculation unit 200 and the total external disturbance torque calculation unit 500.

The first speed calculation unit 200 obtains the backlash torque estimation value calculated by the backlash torque estimation value calculation unit 100, and calculates the first speed using the nominal inertia based on the obtained backlash torque estimation value. 1st speed The calculation unit 200 outputs the calculated first speed to the second speed calculation unit 300.

The second speed calculation unit 300 obtains the motor speed calculated by the speed calculator 13 and the first speed calculated by the first speed calculation unit 200. The second speed calculation unit 300 calculates the second speed excluding the backlash torque estimation value by subtracting the first speed from the motor speed. The second speed calculation unit 300 outputs the calculated second speed to the external disturbance torque estimation value calculation unit 400.

The external disturbance torque estimation value calculation unit 400 calculates the disturbance torque estimation value based on the second speed, excluding the backlash torque estimation value. That is, the external disturbance torque estimation value calculation unit 400 obtains the torque command and the second speed calculated by the second speed calculation unit 300. The external disturbance torque estimation value calculation unit 400 calculates the disturbance torque estimation value excluding the backlash torque estimation value based on the torque command and the second speed. The external disturbance torque estimation value calculation unit 400 outputs the calculated external disturbance torque estimation value to the total external disturbance torque calculation unit 500.

The total external disturbance torque calculation unit 500 obtains the estimated external disturbance torque calculated by the estimated external disturbance torque calculation unit 400 and the estimated backlash torque calculated by the estimated backlash torque calculation unit 100. The total external disturbance torque calculation unit 500 calculates the total external disturbance torque by adding the estimated external disturbance torque value and the estimated backlash torque value, and feeds back the calculated total external disturbance torque.

Furthermore, in this embodiment, the compensation data storage unit 11 is arranged on the side of the disturbance observer 10. The disturbance observer 10 may include the backlash torque estimation value calculation unit 100. Therefore, the compensation data storage unit 11 can also It is arranged on the encoder 3 side.

Next, an example of the specific configuration of the compensation data storage unit 11 and the disturbance observer 10 will be described.

First, in the motor control device 1, the following equations (1) and (2) are established from the motion equation of the motor.

Jn ω m. s=Tcmd-TD=Tcmd-TL-TR. . . (1)

TL=Tcmd-Jn{ ω m+TR/(Jn.s)}. s. . . (2)

For this reason, in the formula (2), let the backlash torque component estimated value be TR^, and the other component estimated value TL^, the total external disturbance torque estimated value TD^ can be estimated by the following formula.

TDˆ=TLˆ+TRˆ=gd/(s+gd)[Tcmd-Jn{ ω m+TRˆ/(Jn ．s). s}]+TRˆ. . (3)

Among them, Jn: nominal value of inertia, ωm: motor speed, Tcmd: torque command, gd: cut-off frequency of low-pass filter

By using the above equation (3), it is possible to construct an external disturbance observer 10 that compensates for both the backlash torque data stored in the compensation data storage unit 11 and the instantaneous external disturbance estimation.

FIG. 2 shows an example of the configuration of the disturbance observer 10 provided in the motor control device 1 based on the above equation (3).

Here, the backlash torque data stored in the compensation data storage unit 11 is the backlash torque data corresponding to the motor position measured and memorized in advance.

As shown in FIG. 2, the disturbance observer 10 uses the backlash torque data stored in the compensation data storage unit 11 to obtain the backlash torque estimation value a1 based on the motor position detected by the encoder 3. Disturbance observation The device 10 uses the first speed calculator 12 to calculate the first speed a2 based on the estimated value of the backlash torque using the nominal inertia.

Next, the disturbance observer 10 uses the speed calculator 13 to obtain the motor speed a3 from the motor position. The disturbance observer 10 calculates the second speed a4 excluding the estimated value of backlash torque by subtracting the first speed a2 based on the estimated value of backlash torque from the motor speed a3.

Next, the external disturbance observer 10 multiplies the torque command Tcmd and the second speed a4 from the estimated value of the backlash torque by the first multiplier 14 multiplied by gd. The value a5 obtained by the Jn times method is added. The disturbance observer 10 calculates the value a6 by passing the added value through the low-pass filter 15 of gd/(s+gd). The disturbance observer 10 subtracts the second speed a4 from the value a6 by removing the backlash torque estimation value by using the second multiplier 16 to multiply gd. Jn times the value a7. Through this, the disturbance observer 10 calculates the disturbance torque estimated value a8 excluding the backlash torque estimated value.

Finally, the external disturbance observer 10 estimates the total external disturbance torque TD^ by adding the estimated value a8 of the disturbance torque and the estimated value a1 of the backlash torque except for the estimated value of the backlash torque.

Furthermore, the disturbance observer 10 may also be constituted by an equivalent circuit according to the above equation (3). The low-pass filter may also be configured as a filter other than the primary filter, such as a secondary filter.

FIG. 3 shows an example of the configuration of a speed control system to which the external disturbance observer 10 provided in the motor control device 1 is applied.

Motor control device 1, using encoder 3 to detect the motor position. The motor control device 1 calculates the motor speed by differentiating the position of the motor by the speed calculator 13.

Next, the motor control device 1 compares the speed command with the motor speed (subtracts the motor speed from the speed command). Furthermore, the motor control device 1 uses the result of this subtraction to use the speed controller 4 to calculate a torque command based on the speed control.

Next, the motor control device 1 adds the total external disturbance torque TD^ estimated by the external disturbance observer 10 to the calculated torque command based on the speed control. Through this, the motor control device 1 calculates the torque command Tcmd after the external disturbance suppression compensation (the torque command Tcmd compensated for the external disturbance suppression). The motor control device 1 uses the torque command Tcmd after external disturbance suppression compensation, and uses the torque controller 5 to drive the motor 2.

Through this, based on the motor speed of the motor 2, the external disturbance observer 10 shown in FIG. 2 is used to estimate the total external disturbance torque TD^. The output from the external disturbance observer 10 can be used to perform external disturbance suppression compensation.

Furthermore, in the case of position control, the motor control device 1 can also control the position of the motor by the following actions. That is, the motor control device 1 compares the position detected by the encoder 3 with the position command (calculates the difference between these). The motor control device 1 uses a position controller to calculate a speed command based on the comparison result (calculation result). Furthermore, the motor control device 1 gives the calculated speed command as the speed command in FIG. 3.

Figure 4 shows the simulation results of external disturbance suppression compensation.

The upper part of FIG. 4 shows the response in the speed of the motor. Figure 4 The lower part of represents the response in the torque of the motor. In addition, the waveform of 0~0.5sec indicates the response when the external disturbance observer is not applied (when compensation is not performed). Furthermore, the 0.5~1.0sec waveform represents the response of the conventional disturbance observer shown in Fig. 5. The waveform of 1.0 to 1.5 sec represents the response when the external disturbance observer 10 according to this embodiment is applied.

As shown in FIG. 4, by applying the disturbance observer 10 of the present embodiment, it is understood that the speed ripple and the torque ripple can be greatly reduced.

In this way, in the motor control device 1 of the present embodiment, both the compensation data storage unit 11 for compensating for torque ripple and the disturbance observer 10 for performing instantaneous disturbance estimation are combined. After this, an appropriate instantaneous external disturbance estimation is performed. Furthermore, it is possible to appropriately perform disturbance suppression compensation using the estimated value.

Furthermore, in this embodiment, in the compensation data memory portion 11, as data corresponding to the torque variation of the motor caused by the backlash torque, data (tooth backlash torque) corresponding to the motor position measured in advance is stored as data Clearance torque data). As the data corresponding to the torque variation of the motor caused by the backlash torque, data on the frequency, amplitude, and phase of m sine waves (m is a natural number greater than 2) can also be stored. In this case, the disturbance observer 10 creates m sine waves based on the m frequencies, amplitudes, and phases stored in the compensation data storage unit 11. The disturbance observer 10 generates a synthetic sine wave signal by adding these. The disturbance observer 10 is based on the synthesized sine wave signal to obtain The estimated value of backlash torque corresponding to the motor position is obtained.

The disturbance observer 10 can also calculate the backlash torque estimation value from the motor position input from the compensation data storage unit 11, and perform external disturbance suppression compensation based on the calculated backlash torque estimation value. The backlash torque estimation value calculation unit 100 may also have a compensation data storage unit 11 to input the motor position detected by the encoder 3, and calculate the backlash torque estimation value from the motor position input from the compensation data storage unit 11 , And output the calculated backlash torque estimation value to the first speed calculation unit 200 and the total external disturbance torque calculation unit 500.

The first speed calculation unit 200 can also input the backlash torque estimation value calculated by the backlash torque estimation value calculation unit 100, and calculate the first speed from the input backlash torque estimation value using the nominal inertia. The calculated first speed is output to the second speed calculation unit 300.

The structure of the disturbance observer 10 may be constituted by an equivalent circuit according to the above-mentioned equation (3), or the low-pass filter may be constituted as a filter other than the second order or the first order.

It is also possible to construct an external disturbance observer 10 that compensates for both the compensation data storage unit 11 and the instant external disturbance estimation by using the above-mentioned formula (3).

The disturbance observer 10 can also use the compensation data storage unit 11 to obtain the backlash torque estimation value a1 based on the motor position detected by the encoder 3.

Moreover, in the case of position control, it can also be used to compare the position detected by the encoder 3 with the original position command. The controller calculates the speed command, and controls the position of the motor by giving it as the speed command in FIG. 3.

The total external disturbance torque calculation unit 500 may also be a total external disturbance torque estimation value calculation unit.

The motor control device of this embodiment may be the following first to fourth motor control devices.

The first motor control device includes: an external disturbance observer, which calculates the position corresponding to the motor from the compensation data memory unit that memorizes the data corresponding to the torque change caused by the backlash torque of the motor Based on the calculated backlash torque estimated value, external disturbance suppression compensation is performed.

The second motor control device is in the first motor control device, and the external disturbance observer includes: a backlash torque estimation value calculation unit that calculates the backlash torque estimation value from the compensation data storage unit; The backlash torque estimation value calculated by the backlash torque estimation value calculation unit uses the nominal inertia to calculate the first speed first speed calculation unit; subtracts the first speed calculated by the first speed calculation unit from the motor speed to calculate The second speed calculation section of the second speed that removes the backlash torque estimated value; based on the second speed calculated by the aforementioned second speed calculation section, calculates the external disturbance torque estimated value excluding the backlash torque estimated value Disturbance torque estimation value calculation unit; and by adding the disturbance torque estimation value calculated by the aforementioned disturbance torque estimation value calculation unit to the backlash torque estimation value calculated by the aforementioned backlash torque estimation value calculation unit Calculate the total external disturbance torque calculation part of the total external disturbance torque.

The third motor control device is the first or second motor control device, and the aforementioned external disturbance observer is constituted by an equivalent circuit based on the following equation.

TD^=gd/(s+gd)[Tcmd-Jn{ωm+TR^/(Jn.s). s}]+TR^

Among them, TD^: estimated value of total external disturbance torque, TR^: estimated value of backlash torque, Jn: nominal value of inertia, ωm: motor speed, Tcmd: torque command, gd: cut-off frequency of low-pass filter.

The fourth motor control device is provided with: a compensation data storage unit that memorizes the data corresponding to the torque change caused by the backlash torque of the motor; and calculates the backlash torque estimation value from the compensation data storage unit, based on the calculated value The estimated value of backlash torque performs external disturbance suppression compensation external disturbance observer.

According to the first to fourth motor control devices, it is possible to provide a motor control device that can estimate external disturbance torque including the backlash torque or torque ripple of the motor without being affected by the quantization error of the encoder, and use the external The disturbance observer performs external disturbance suppression compensation, which can suppress the influence of friction, etc., and reduce the speed ripple and torque ripple of the motor.

For the purpose of illustration and description, the above detailed description has been presented. There are many modifications and variations based on the above teachings. It is not intended to exhaust or limit the subject matter of the invention described herein to the specific precise form disclosed. Although the subject matter of the invention has been described in terms of specific structural features and/or methodological behaviors, it should be understood that the subject matter of the invention defined in the scope of the attached patent application is not necessarily limited to the specific features or behaviors mentioned above. On the contrary, the specific characteristics and behaviors mentioned above are revealing acts Implement the attached example form of the scope of patent application.

1‧‧‧Motor control device

2‧‧‧Motor

3‧‧‧Encoder

4‧‧‧Speed Controller

5‧‧‧torque controller

10‧‧‧External Disturbance Observer

11‧‧‧Compensation data memory

12‧‧‧The first speed calculator

13‧‧‧Speed Calculator

14‧‧‧The first multiplier

15‧‧‧Low Pass Filter

16‧‧‧The second multiplier

Claims (2)

A motor control device is provided with an external disturbance observer; the external disturbance observer calculates the backlash torque estimation value corresponding to the position of the motor from the compensation data memory part, and performs external disturbance based on the calculated backlash torque estimation value Disturbance suppression compensation; the compensation data memory unit stores the data corresponding to the torque change of the motor caused by the backlash torque; it is characterized by: the aforementioned external disturbance observer includes: the backlash torque estimation value calculation unit, which is derived from The aforementioned compensation data storage unit calculates the backlash torque estimation value; the first speed calculation unit is based on the backlash torque estimation value calculated by the aforementioned backlash torque estimation value calculation unit, and the nominal inertia is used to calculate the first speed; The second speed calculation unit is to subtract the first speed calculated by the first speed calculation unit from the motor speed to calculate the second speed excluding the backlash torque estimation value; the external disturbance torque estimation value calculation unit is According to the second speed calculated by the second speed calculation unit, the estimated value of the disturbance torque is calculated excluding the estimated value of the backlash torque; and the total external disturbance torque calculation unit is used to calculate the estimated value of the external disturbance torque The estimated external disturbance torque calculated by the calculation unit and the estimated backlash torque calculated by the estimated backlash torque calculation unit are added to calculate the total external disturbance torque. Such as the motor control device of claim 1, wherein the aforementioned disturbance observer is constituted by an equivalent circuit according to the following formula TD^=gd/(s+gd)[Tcmd-Jn{ ω m+TR ^/(Jn.s). s}]+TR^where TD^: estimated value of total external disturbance torque, TR^: estimated value of backlash torque, Jn: nominal value of inertia, ωm: motor speed, Tcmd: torque command, gd: low-pass filter The cutoff frequency of the converter.

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