TW202111456A - Servo amplifier and servo system including a torque control unit, a disturbance torque estimation unit, a load torque estimation unit and an output unit - Google Patents

Abstract

The invention provides a servo amplifier and a servo system. The servo amplifier includes a torque control unit, a disturbance torque estimation unit, a load torque estimation unit and an output unit. The torque control unit is configured to control the torque of a motor based on a torque command of the motor that moves a movable portion in a movement direction having a vertical direction component. The disturbance torque estimation unit is configured to estimate the disturbance torque experienced by the motor. The load torque estimation unit subtracts a gravitational torque generated by a gravity of the movable portion from the disturbance torque estimated by the disturbance torque estimation unit to estimate a load torque received by the motor. The output unit outputs information related to the load torque estimated by the load torque estimation unit to the outside of the servo amplifier.

Description

Servo amplifier and servo system

The present invention relates to a servo amplifier and a servo system.

In the past, a motor control device equipped with a load torque observer is well known. The load torque observer can estimate the load torque borne by the motor based on the torque command and the motor speed (for example, refer to Patent Document 1). [Prior Technical Literature] [Patent Literature] [Patent Document 1] (Japan) JP 2012-130214 A

[The problem to be solved by the invention] However, in the prior art, the estimated load torque is applied to motor control for the purpose of suppressing disturbance, and the information related to the estimated load torque cannot be monitored from the outside. Therefore, the purpose of the present disclosure is to provide a servo amplifier and a servo system that can monitor information related to the estimated load torque from the outside. [Means used to solve the problem] The present disclosure provides a servo amplifier including: A torque control unit, which controls the torque of the motor based on a torque command of the motor that causes the movable unit to move in a movement direction having a vertical direction component; A disturbance torque estimation unit, which estimates the disturbance torque borne by the motor; The load torque estimation unit subtracts the gravitational torque generated by the gravity acting on the movable part from the disturbance torque estimated by the disturbance torque estimation unit, thereby applying the load to the motor To estimate the load torque; and The output unit outputs information related to the load torque estimated by the load torque estimation unit to the outside of the servo amplifier. In addition, the present disclosure provides a servo amplifier including: A speed control unit that generates a torque command of the motor based on a speed command of the motor that causes the movable part to move in a movement direction having a vertical direction component; A torque control unit, which controls the torque of the motor according to the torque command; A load torque estimation unit, which estimates the load torque borne by the motor according to the speed command; and The output unit outputs information related to the load torque estimated by the load torque estimation unit to the outside of the servo amplifier. In addition, the present disclosure provides a servo system including a servo amplifier and an external device provided outside the servo amplifier, the servo amplifier including: A torque control unit, which controls the torque of the motor based on a torque command of the motor that causes the movable unit to move in a movement direction having a vertical direction component; A disturbance torque estimation unit, which estimates the disturbance torque borne by the motor; The load torque estimation unit subtracts the gravitational torque generated by the gravity acting on the movable part from the disturbance torque estimated by the disturbance torque estimation unit, thereby applying the load to the motor To estimate the load torque; and The output unit outputs information related to the load torque estimated by the load torque estimation unit to the outside of the servo amplifier. In addition, the present disclosure provides a servo system including a servo amplifier and an external device provided outside the servo amplifier, the servo amplifier including: A speed control unit that generates a torque command of the motor based on a speed command of the motor that causes the movable part to move in a movement direction having a vertical direction component; A torque control unit, which controls the torque of the motor according to the torque command; A load torque estimation unit, which estimates the load torque borne by the motor according to the speed command; and The output unit outputs information related to the load torque estimated by the load torque estimation unit to the outside of the servo amplifier. [Effects of the invention] According to the technology of the present disclosure, it is possible to provide a servo amplifier and a servo system that can monitor information related to the estimated load torque from the outside.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. First, in order to compare with the embodiment of the present disclosure, the configuration of a servo system of a comparison method will be described. Fig. 1 is a diagram showing an example of the configuration of a servo system in a comparison mode. The servo system 100 shown in FIG. 1 is a motor system which controls the motor 9 for moving the movable part which is not shown in figure. The servo system 100 includes a speed control unit 1, an adder 2, a torque control unit 3, a speed detection unit 4, a load torque estimation unit 5, a control filter 8, a motor 9, and a position detector 10. The torque control unit 3 controls the torque of the motor 9 based on the torque command Tr. The position detector 10 detects the position (rotation position θ) of the motor 9. The position detector is also called PG. The speed detection unit 4 detects the speed (angular speed ω) of the motor 9 based on the temporal change of the rotational position θ detected by the position detector 10. The speed control unit 1 generates a feedback torque command Tb for causing the angular velocity ω detected by the speed detection unit 4 to follow a speed command ωr supplied from a control block of the upper stage not shown in the figure. In addition, the servo system 100 includes a load torque estimation unit 5 for estimating the load torque TL received by the motor 9. The load torque estimation unit 5 can estimate the load torque TL based on the torque command Tr and the angular velocity ω detected by the speed detection unit 4. When the generated torque of the motor 9 is set to T, the moment of inertia (inertia value) of the motor 9 is set to J, and the angular acceleration of the motor 9 is set to dω/dt, the load torque TL includes In the case of the torque (gravity torque) generated by the gravity on the movable part that is moved by the motor 9, the following relationship holds. TL=T-J×dω/dt　　　　･･･Equation 1 Therefore, the load torque estimation unit 5 can estimate the load torque TL by subtracting the torque (J×dω/dt) calculated by the torque calculation unit 6 from the torque command Tr by the subtractor 7. The control filter 8 performs filter processing on the load torque TL (estimated load torque TLe) estimated by the load torque estimation unit 5 to generate a compensated load torque TLc. The adder 2 can generate the torque command Tr by adding the feedback torque command Tb generated by the speed control unit 1 to the compensation load torque TLc generated by the control filter 8. However, in the servo system 100 shown in FIG. 1, the load torque TL estimated by the load torque estimation unit 5 is applied to motor control for the purpose of suppressing interference, and cannot be correlated with the estimated load torque TLe from the outside. Information to monitor. Therefore, the servo amplifier and the servo system of the embodiment of the present disclosure have a configuration capable of monitoring information related to the estimated load torque from the outside. Next, the configuration of the servo amplifier and the servo system of the embodiment of the present disclosure will be described. Fig. 2 is a diagram showing an example of the configuration of a servo system according to the first embodiment. The servo system 120 shown in FIG. 2 is a motor drive control system that drives and controls a motor 19 that can move the movable part 40 in a movement direction having a vertical component through the arm 41. The servo system 120 can control the position of the movable part 40 at a desired position by, for example, driving and controlling the motor 19. The servo system 120 includes a servo amplifier 111 and an external device 122. The external device 122 is a device provided outside the servo amplifier 121, and has a monitoring function for monitoring the load torque TL. The external device 122 may be connected to the servo amplifier 121 by analog voltage, wired communication or wireless communication. The external device 122 is, for example, a control device such as a programmable logic controller. The servo amplifier 111 is a motor drive device that drives the motor 19. The motor 19 uses the arm 41 to move the movable portion 40 in a moving direction having a vertical component. For example, by driving the motor 19, The position of the movable part 40 is controlled to a desired position. Regarding the servo amplifier 111, for example, as its main components, a speed control unit 11, an adder 12, a torque control unit 13, a speed detection unit 14, a load torque estimation unit 15, a control filter 18, and an output unit 23 can be provided. . The torque control unit 13 controls the torque of the motor 19 based on the torque command Tr. The position detector 20 detects the position (rotation position θ) of the motor 19. The speed detection unit 14 detects the speed (angular velocity ω) of the motor 19 based on the temporal change of the position detected by the position detector 20. The speed control unit 11 generates a feedback torque command Tb for causing the angular velocity ω detected by the speed detection unit 14 to follow a speed command ωr supplied from a control block of the previous stage (not shown). For example, the speed control unit 11 can perform PI control (proportional control) by adopting a method such that the deviation between the angular velocity ω detected by the speed detecting unit 14 and the speed command ωr supplied from a control block of the previous stage not shown in the figure is zero. Control and integral control) to generate feedback torque command Tb. The load torque estimation unit 15 performs a calculation of the load torque TL (load torque TL applied to the motor 9) applied to the motor 9 based on the torque command Tr or the torque detection value Tde, and the angular velocity ω detected by the speed detection unit 14. estimate. The load torque estimation unit 5 is, for example, a load torque observer that estimates the load torque TL. The torque detection value Tde used in the estimation of the load torque TL indicates the torque value of the motor 19 detected by the torque detection unit 21. In other words, the torque command Tr may be used for the estimation of the load torque TL, and the torque detection value Tde may also be used. For example, in a case where the torque detection unit 21 is not included in the servo amplifier 111, the torque command Tr can be used to estimate the load torque TL. Hereinafter, the load torque TL estimated by the load torque estimation unit 15 is also referred to as "estimated load torque TLe". In the comparison method shown in Fig. 1, the load torque TL includes gravity torque, and the load torque TL is estimated. The first embodiment shown in FIG. 2 shows a case where the load torque TL is estimated so that the load torque TL does not include the gravity torque. The gravitational torque refers to the torque required to cancel the gravitational force acting on the movable portion 40 that is moved by the arm portion 41 in the movement direction having a vertical direction component. The motor 19 moves the arm 41 connected to the rotation output shaft of the motor 19 via a gear or the like in a direction having a vertical component (for example, an up-and-down direction), so that the movable part 40 connected to the arm 41 can be vertically aligned. The direction component moves in the direction of movement. The movable part 40 is, for example, a pressing operation part that presses the work W fixed on the mounting table from above. The arm portion 41 can move the movable portion 40 in a movement direction having a vertical component by using a ball screw, for example. It should be noted that the movable portion 40 may also perform other work operations such as a pressing operation, a drilling operation, and a cutting operation. For example, consider the case where the arm portion 41 is a ball screw capable of moving the movable portion 40 in the extending direction. Assuming that the gravity acting at the center of gravity of the movable part 40 is Fg, the gravity component in the extending direction of the arm 41 (moving direction of the movable part 40) in the gravity Fg is Fg', the gravity torque is Tg, the vertical direction and the arm are The angle between the extending directions of 41 is α, and the lead of the ball screw is BP. When the angle α is zero, it means that the movable portion 40 moves only in the vertical direction. At this time, the gravity component Fg' and the gravity torque Tg respectively satisfy the following relationships. Fg’=Fg×cosα　　　　　　　　 ･･･Equation 2 Tg=(BP/2π)×Fg’　　　　　　　 ･･･Equation 3 In addition, assuming that the torque generated by the motor 19 is T, the moment of inertia (inertia value) of the movable part of the motor 19 and the load machinery directly or indirectly connected to the motor 19 is J, the angular acceleration of the motor 19 is dω/dt, and the motor 19 bears The disturbance torque of is Td, and the gravity torque contained in the disturbance torque Td is Tg. At this time, when the load torque TL does not include the gravity torque Tg, it satisfies TL=Td-Tg=T-J×dω/dt-Tg　　　　･･･Equation 4 The relationship. By subtracting (subtracting) the gravity torque Tg from the load torque TL of the estimation target, the estimation accuracy of the load torque TL can be improved. In the case of estimating the load torque TL using Formula 4, the load torque estimating section 15 has, for example, a disturbance torque estimating section 28 and a subtractor 30. The disturbance torque estimation unit 28 can bear the disturbance torque Td to the motor 19 (the disturbance torque Td applied to the motor 19) based on the torque command Tr or the torque detection value Tde and the angular velocity ω detected by the speed detection unit 14 Make an estimate. The disturbance torque estimation unit 28 is, for example, a disturbance torque observer that can estimate the disturbance torque Td. Hereinafter, the disturbance torque Td estimated by the disturbance torque estimation unit 28 is also referred to as “estimated disturbance torque Tdie”. The disturbance torque estimation unit 28 has, for example, the same configuration as the load torque estimation unit 5 shown in FIG. 1. In this case, the disturbance torque estimation unit 28 uses the subtractor 7 to subtract the torque calculated by the torque calculation unit 6 (J×dω/dt ), the disturbance torque Td can be estimated. It should be noted that the disturbance torque estimation unit 28 is not limited to this configuration, and may have any known configuration. As shown in Equation 4, the load torque TL can be estimated by subtracting the gravity torque Tg from the disturbance torque Td. Therefore, the load torque estimation unit 15 can estimate the load torque TL by subtracting the gravity torque Tg from the disturbance torque Td (estimated disturbance torque Tdie) estimated by the disturbance torque estimation unit 28 by using the subtractor 30. . In other words, the high-precision estimated load torque TLe can be obtained by the compensation of the gravity torque Tg. For example, the load torque estimation unit 15 can calculate the load torque TL by subtracting a certain (fixed) gravity torque Tg from the disturbance torque Td (estimated disturbance torque Tdie) estimated by the disturbance torque estimation unit 28 estimate. When the angle α is fixed and the movable portion 40 moves in a straight line in the vertical direction, it can be seen from Equation 3 that the gravitational torque Tg is a fixed value. Therefore, a certain (fixed) gravitational torque Tg can be stored (stored) in the servo amplifier 111 in advance. Alternatively, the load torque estimation unit 15 may subtract the gravitational torque Tg supplied from the outside of the servo amplifier from the disturbance torque Td (estimated disturbance torque Tdie) estimated by the disturbance torque estimation unit 28, and the load torque TL is estimated. Due to changes in the operating state and/or setting conditions, there are cases where the mass of the movable portion 40 changes or the angle α changes. In the case that the external machine 122 has such variable information, the external machine 122 can calculate the value of the gravity torque Tg at every moment, and the calculated value of the gravity torque Tg at every moment will be received from the external machine 122 through communication. It is supplied to the load torque estimation unit 15 of the servo amplifier 111. In this way, even if the gravity torque Tg changes, the servo amplifier 111 can obtain the gravity torque Tg from the external machine 122 and apply it to the estimation of the load torque TL. The control filter 18 can generate a compensated load torque TLc by performing filter processing on the estimated load torque TLe. The adder 12 can generate the torque command Tr by adding the feedback torque command Tb generated by the speed control unit 11 to the compensation load torque TLc generated by the control filter 18. The servo amplifier 111 includes an output unit 23 that outputs information (monitoring information) related to the estimated load torque TLe to the outside of the servo amplifier 111. Accordingly, information related to the estimated load torque TLe can be output to the outside of the servo amplifier 111 (for example, the external device 122). Therefore, not only can the estimated load torque TLe be reflected in the calculation of the torque command Tr for the purpose of suppressing interference for the servo control of the motor 19, but it can also be used for servo control from the outside of the servo amplifier 111 (for example, the external device 122). The information related to the estimated load torque TLe is monitored. For example, if an abnormality occurs in the movable portion 40 or the motor 19 itself that controls the position and the like by the motor 19 (for example, deterioration over the years, contact with foreign objects, etc.), the estimated load torque TLe also changes. Therefore, by monitoring the information related to the estimated load torque TLe output from the output unit 23 outside the servo amplifier 111, it is possible to detect an abnormality occurring in the movable unit 40 or the motor 19 outside the servo amplifier 111. As the information related to the estimated load torque TLe, for example, the value of the estimated load torque TLe, the result of abnormality determination based on the estimated load torque TLe in the servo amplifier 111, and the like can be cited. The output unit 23 may output the information related to the estimated load torque TLe to the outside by means of analog output, and may also output it to the outside by means of wired communication or wireless communication. For example, the output unit 23 may convert the value of the estimated load torque TLe into an analog voltage value and output it to the outside. According to this, the external device 122 of the servo amplifier 111 can detect the value of the estimated load torque TLe based on the analog voltage value output from the output unit 23. In addition, when the output unit 23 uses a predetermined carrier wave to output the value of the estimated load torque TLe by means of communication, similarly, the external device 122 of the servo amplifier 111 receives the carrier wave output from the output unit 23. , Can also detect the value of the estimated load torque TLe. For example, the output unit 23 may perform peak hold on the estimated value of the load torque, and send the peak hold value of the estimated value to the outside of the servo amplifier. In the same way, the output unit 23 can convert the information indicating the result (normal or abnormal) obtained by the abnormality determination based on the estimated load torque TLe inside the servo amplifier 111 into an analog voltage value and output it to the outside. A predetermined carrier wave is used to output it to the outside by means of communication. According to this, the external device 122 of the servo amplifier 111 can obtain the result of the abnormality determination of the servo amplifier 111 by detecting the analog voltage or the carrier wave output from the output unit 23. In addition, when the load torque TL is estimated, as described above, the moment of inertia (inertia value J) of the motor 19 and the movable part of the load machine connected to the motor 19 can be used. When the inertia value used in the estimation of the load torque TL also serves as the inertia value used in the determination of the servo control parameter (for example, the control gain A of the proportional control performed by the speed control unit 11), the load torque The inertia value used in the estimation of TL is not limited to the correct setting. The reason is that the inertia value suitable for improving the controllability of the servo control is not necessarily also suitable for improving the estimation accuracy of the load torque TL. In addition, with regard to the moment of inertia ratio used in the determination of the servo control parameters, even if there is some error, as long as there is no obstacle to the servo control, it is possible to set it to 1, 5, 10 times, etc. Approximate value and fine-tuning the gain by auto tuning. In such a case, it is difficult to estimate the load torque TL with high accuracy. In this regard, the servo amplifier 111 shown in FIG. 2 includes a first inertia value setting unit 24 for setting the first inertia value Jc for controlling the motor 19, and a second inertia value Je for setting the second inertia value Je The estimated second inertia value setting unit 26 of the load torque TL. That is, a function is provided that can independently set the inertia values for the estimation of the load torque TL and the control of the motor 19. By providing such a function that can independently set the inertia value, in order to estimate the load torque TL, a more appropriate inertia value can be set, thereby improving the estimation accuracy of the load torque TL. In addition, since appropriate inertia values for the estimation of the load torque TL and the control of the motor 19 can be set separately, the control accuracy of the servo control and the estimation accuracy of the load torque TL can be improved at the same time. For example, the first inertia value setting unit 24 can automatically tune the control gain A based on the input first inertia value Jc, and set the auto-tuned control gain A to the control gain of the proportional control performed by the speed control unit 11. . On the other hand, the second inertia value setting unit 26 can set the input second inertia value Je to the inertia value J used in the load torque estimating unit 15 to estimate the load torque TL (for example, for calculating The above-mentioned (J×dω/dt) inertia value J). It should be noted that the first inertia value Jc or the second inertia value Je may be an estimated value obtained by the inertia value estimation calculation function of the servo amplifier 111, or may be based on the user or from the servo amplifier 111 The value determined by the information input by the external device 122. In addition, the servo amplifier 111 shown in FIG. 2 includes a first filter value setting unit 25 that sets the first filter value Kc for use in controlling the motor 19, and a second filter value Ko for setting the second filter value Ko. The second filter value setting unit 27 outputs monitoring information related to the estimated load torque TLe. In other words, a function is provided that can independently set the output for monitoring information and the filter value for control of the motor 19. By installing such a function that can independently set the filter value, not only the filter value suitable for the servo control of the motor 19 can be set, but also the external device 122 suitable for the servo amplifier 111 can be monitored. Information is set to monitor the filter value. The servo amplifier 111 includes, for example, a control filter 18 for controlling the motor 19 and an output filter 22 for outputting monitoring information. The first filter value setting unit 25 sets the input first filter value Kc to the control filter 18, and the second filter value setting unit 27 sets the input second filter value Ko to the output filter 22. For example, the first filter value Kc is the response time constant of the control filter 18, and the second filter value Ko is the response time constant of the output filter 22, but it is not limited to this, and it may be set to be suitable for The value of the filter processing performed by each filter. The control filter 18 performs filter processing using the first filter value Kc on the estimated load torque TLe, thereby generating a compensated load torque TLc. The output filter 22 performs filter processing using the second filter value Ko on the estimated load torque TLe, thereby generating an estimated load torque TLe suitable for external monitoring. It should be noted that the output filter 22 may be a low-pass filter, a band-pass filter, or a high-pass filter. The filter characteristics suitable for external monitoring can be set. Fig. 3 is a diagram showing an example of the configuration of a servo system according to a second embodiment. The servo system 140 shown in FIG. 3 includes a servo amplifier 121 and an external device 122. It should be noted that, regarding the description of the same configuration and effects as the above-mentioned embodiment, the above-mentioned description is cited here, and the above-mentioned description is omitted or abbreviated. The second embodiment is different from the first embodiment in the configuration of the load torque estimation unit 15. In the second embodiment, the load torque estimation unit 15 uses the high-pass filter 32 to subtract the gravitational torque Tg from the disturbance torque Td (estimated disturbance torque Tdie) estimated by the disturbance torque estimation unit 28. The torque TL is estimated. For the high-pass filter 32, the disturbance torque Td is input, and the gravity torque Tg included in the input disturbance torque Td is attenuated, thereby outputting an estimated load whose gravity torque Tg has been attenuated. Torque TLe. In the case where the frequency component of the gravity torque Tg is a direct current component (for example, when the gravity torque Tg is a fixed value as described above), the disturbance torque Td is subjected to filter processing based on the high-pass filter 32, The estimated load torque TLe in which the DC component corresponding to the gravity torque Tg is attenuated can be obtained. FIG. 4 is an exemplary diagram of each waveform when the gravity torque is included in the estimated load torque, and shows a case where the load torque estimator 5 in the comparison method estimates the load torque TL. FIG. 5 is an exemplary diagram of each waveform when the gravity torque is not included in the estimated load torque, and shows how the load torque estimator 15 in the first or second embodiment estimates the load torque TL . In FIGS. 4 and 5, "speed" indicates the pressing speed (or angular velocity ω) when the movable part 40 presses the metal workpiece W, and "load torque" indicates the estimated load torque TLe calculated inside the servo amplifier . In the case of Figure 4, the metal is pressed by the lowering action, so the load torque is applied near the lower fulcrum. However, it is estimated that the load torque TLe includes about 20% of the gravity torque Tg, so it cannot be accurately measured. Monitor the load torque (press torque in this case). On the other hand, in the case of FIG. 5, the gravitational torque Tg is not included in the estimated load torque TLe, so the estimated load torque TLe can be expressed as an amount that changes on a zero basis, so that the pressing can be accurately and intuitively Torque is monitored. Fig. 6 is a diagram showing an example of the configuration of a servo system according to a third embodiment. The servo system 160 shown in FIG. 6 includes a servo amplifier 131 and an external device 122. It should be noted that, regarding the description of the same configuration and effects as the above-mentioned embodiment, the above-mentioned description is cited here, and the above-mentioned description is omitted or abbreviated. In the third embodiment, the load torque estimation unit 15 estimates the load torque TL based on the speed command ωr of the motor 19, and the load torque TL is changed based on the speed detection value of the motor 19 (the angular velocity ω detected by the speed detection unit 14). The above-mentioned implementation of estimating the moment TL is different. The disturbance torque estimation unit 28 estimates the disturbance torque Td based on the speed command ωr, and accordingly, the load torque estimation unit 15 can estimate the load torque TL. For example, in the calculation of the load torque TL shown in FIG. 1, the angular velocity ω obtained by differentiating the rotational position θ detected by the position detector 20 by the speed detection unit 14 is used. However, the rotational position θ detected by the position detector 20 contains a noise component, so when it is differentiated, a large noise component tends to appear in the angular velocity ω. In particular, if the inertia value is large, noise components that are not suitable for monitoring may appear. If the angular velocity ω obtained by the velocity detection section 14 is further differentiated to obtain the angular acceleration dω/dt, the noise component may further increase. In contrast, the load torque estimation unit 15 shown in FIG. 6 calculates the load torque TL using angular acceleration dω/dt obtained by differentiating the speed (command speed) commanded by the speed command ωr. The speed (command speed) commanded by the speed command ωr is an internal value of the servo amplifier 131, so the noise component is small. Therefore, by using the speed commanded by the speed command ωr (command speed), it is possible to perform high-precision monitoring with less noise. It should be noted that as for the load torque estimation unit 15 shown in FIG. 6, as shown in FIG. 3, a high-pass filter 32 may also be used to estimate the load torque TL. FIG. 7 is an exemplary diagram of each waveform when the feedback speed (the angular velocity ω detected by the speed detection unit 14) is used for the estimation of the load torque. FIG. 8 is an illustration diagram of each waveform when a command speed (speed commanded by a speed command ωr) is used for the estimation of the load torque. In the case of FIG. 7, since the differential of the feedback speed is used, the estimated load torque TLe can be calculated immediately following the change in the angular speed ω when the load torque TL is applied based on the actual load. On the other hand, as shown in FIG. 8, when the derivative of the command speed is used, the change in the angular velocity ω when the load torque TL is applied based on the actual load is not reflected in the estimation of the load torque TL. For this reason, as the torque command Tr, which is the result of the speed control, rises, the estimated load torque TLe also rises. That is, the response speed of the estimated load torque TLe depends on the response speed of the speed control. However, the response of speed control is usually about 30~100Hz (about 5~1ms after conversion to the time constant), which is very fast, so there is no problem in practical applications. In addition, in the waveform of the estimated load torque TLe exemplified in FIG. 5, in order for the external device 122 to detect the peak value of the estimated load torque TLe output from the output unit 23, sampling of about 1 ms is required. When the peak detection is performed by bus communication, it is required to perform bus communication in about 1 ms. Therefore, the peak detection on the external device 122 side requires high accuracy, and it is not easy to perform high-precision peak detection. . Therefore, with the output unit 23 in each embodiment, for example, as shown in FIG. 9, the estimated value of the load torque TL is peak-held each time and the peak-hold value of the estimated value is sent to the outside of the servo amplifier. Reset is performed at all times, so that the estimated value of the load torque TL can be held at the peak value again. The output unit 23 peak-holds the estimated load torque TLe during transmission and reception through bus communication, sends the latest peak-hold value to the external device 122 during transmission, and resets the internal peak-hold value . According to this, for example, even when the bus communication is performed in about 5 ms, the external device 122 can perform peak detection without omission. Therefore, even in a system in which data is updated late, the external device 122 can obtain the peak value of the estimated load torque TLe without fail, and execute the abnormality determination of the motor 19 and the like with high accuracy based on the estimated load torque TLe. As an example of requiring detection of the peak torque on the side of the external device 122, for example, there are the following cases. ・The information of one cycle of the machine only exists on the side of the external device 122, and the servo amplifier side does not know which interval peak value should be detected; ・The condition for determining which peak of a plurality of peaks in one cycle is to be used for abnormality determination only exists on the side of the external device 122. Alternatively, the output unit 23 in each embodiment may time-integrate the estimated value of the load torque TL, and send the time-integrated value of the estimated value to the outside of the servo amplifier. According to this, even if the difference between the normal time and the abnormal time of the peak of the estimated load torque TLe is small, the external device 122 can perform the abnormality determination of the motor 19 and the like with high accuracy based on the time integral value supplied from the output unit 23. FIG. 12 is an exemplary diagram of each waveform when the estimated value of the load torque is time-integrated, showing the waveforms of the speed and the load torque when the servo system of this embodiment is applied to a pressing machine The comparison result of normal and abnormal conditions. In FIG. 12, "speed" indicates the pressing speed (or angular velocity ω) when the movable portion 40 presses the metal socket terminal, and "load torque" indicates the estimated load torque TLe calculated internally in the servo amplifier. In FIG. 12, "normal" means that the crimping of the socket terminal 60 and the electric wire 51 is normal (refer to FIG. 10), and "abnormal" means that the crimping of the socket terminal 60 and the electric wire 51 is abnormal (refer to FIG. 11). 10 shows that the movable part 40 of the pressing machine presses the root 61 of the socket terminal 60 together with the wire 53 exposed by peeling off the cover 52 of the front end of the wire 51, whereby the wire 53 and the root 61 are pressed The normal state of crimping. 11 shows that the movable part 40 of the pressing machine presses the root 61 of the socket terminal 60 in the state where the cover 52 of the front end of the wire 51 is not peeled off but covers the wire 53, whereby the wire 51 and The root 61 is in an abnormal state where it is crimped. In the abnormal waveform illustrated in FIG. 12, since the crimping was performed with the cover 52 covering the wire 51, the presence of foreign matter (cover 52) caused the estimated load torque TLe to be earlier than the normal waveform. The ground has been enlarged on the negative side. The output unit 23 performs the estimated load torque TLe, for example, while the angular velocity ω is lower than the predetermined speed threshold ωa (for example, -200 rpm) and the estimated load torque TLe is lower than the predetermined torque threshold TLa (for example, -20%).的 time integration. When the time integration is performed under this condition, the output unit 23 performs time integration in the period t1-t3 when abnormal, and performs time integration in the period t2-t3 when it is normal. From this, it is possible to clearly distinguish the difference between the time integral value (corresponding to the area of the shaded part in FIG. 12) between abnormal and normal time. In this way, even when it is difficult to determine the peak value of the estimated load torque TLe, it is possible to easily determine the abnormality of the motor 19 and the like by using the time-integrated value for comparison. In this way, according to the above-described embodiment, since the monitoring information related to the estimated load torque TL is externally output, the information related to the estimated load torque can be externally monitored. It should be noted that in the above-mentioned embodiment, the functions of the estimated torque estimating unit and other parts of the servo amplifier can be executed by a processor (for example, CPU (Central Processing Unit)) in a readable manner. It is realized by a program stored in a memory. Although the servo amplifier and the servo system have been described above with the embodiment, the present invention is not limited to the above embodiment. Within the scope of the present invention, various modifications and improvements can be made, such as combining or substituting a part or all of other embodiments with them.

15: Load torque estimation section 18: Control filter 22: output filter 23: output section 24: The first inertia value setting part 25: The first filter value setting section 26: The second inertia value setting part 27: Second filter value setting section 28: Disturbance torque estimation section 29: Friction torque estimation section 30: subtractor 32: high pass filter 40: movable part 100, 120, 140, 160: Servo system 111, 121, 131: Servo amplifier 122: external machine

[Fig. 1] A diagram showing an example of the configuration of a servo system of a comparison method. [Fig. 2] A diagram showing an example of the configuration of a servo system according to the first embodiment. [Fig. 3] A diagram showing an example of the configuration of a servo system according to a second embodiment. [Fig. 4] Illustrative diagrams of respective waveforms in the case where the gravity torque is included in the estimated load torque. [FIG. 5] Illustrative diagrams of respective waveforms in the case where the gravitational torque is not included in the estimated load torque. [Fig. 6] A diagram showing an example of the configuration of a servo system according to a third embodiment. [FIG. 7] Illustrative diagrams of respective waveforms in the case where the feedback speed is used for the estimation of the load torque. [FIG. 8] Illustrative diagrams of respective waveforms when the command speed is used for the estimation of the load torque. [FIG. 9] Illustrative diagrams of respective waveforms when the estimated value of load torque is peak held. [Fig. 10] A schematic diagram showing that the crimping of the terminal and the wire is in a normal state. [Fig. 11] A schematic diagram showing that the crimping of the terminal and the wire is in an abnormal state. [FIG. 12] Illustrative diagrams of respective waveforms when the estimated value of load torque is time-integrated.

120: Servo system

122: external machine

111: Servo amplifier

11: Speed control department

12: adder

13: Torque control department

14: Speed detection department

15: Load torque estimation section

18: Control filter

19: Motor

20: position detector

21: Torque detection department

22: output filter

23: output section

24: The first inertia value setting part

25: The first filter value setting section

26: The second inertia value setting part

27: Second filter value setting section

28: Disturbance torque estimation section

30: subtractor

40: movable part

41: Arm

Jc: 1st inertia value

Kc: the first filter value

Je: 2nd inertia value

Ko: 2nd filter value

ωr: Speed command

A: Control gain

ω: angular velocity

θ: Rotation position

Tb: feedback torque command

TLc: Compensate load torque

Tg: gravitational torque

Tdie: Estimated disturbance torque

TLe: Estimated load torque

Tr: Torque command

Tde: Torque detection value

TL: Load torque

Td: disturbance torque

W: Workpiece

Claims (13)

A servo amplifier with: A torque control unit, which controls the torque of the motor based on a torque command of the motor that causes the movable unit to move in a movement direction having a vertical direction component; A disturbance torque estimation unit, which estimates the disturbance torque borne by the motor; The load torque estimation unit subtracts the gravitational torque generated by the gravity acting on the movable portion from the disturbance torque estimated by the disturbance torque estimation unit, thereby applying the load to the motor To estimate the load torque; and The output unit outputs information related to the load torque estimated by the load torque estimation unit to the outside of the servo amplifier. The servo amplifier according to claim 1, wherein The load torque estimation unit subtracts the fixed gravity torque from the disturbance torque estimated by the disturbance torque estimation unit, thereby estimating the load torque. The servo amplifier according to claim 1, wherein The load torque estimation unit subtracts the gravity torque supplied from the outside of the servo amplifier from the disturbance torque estimated by the disturbance torque estimation unit, thereby estimating the load torque. The servo amplifier according to claim 1, wherein The load torque estimation unit uses a high-pass filter to subtract the gravity torque from the disturbance torque estimated by the disturbance torque estimation unit, thereby estimating the load torque. The servo amplifier according to any one of claims 1 to 4, further comprising: The speed control unit generates the torque command based on the speed command of the motor, Wherein, the load torque estimation unit estimates the load torque according to the speed command. The servo amplifier according to claim 5, wherein: The load torque estimation unit estimates the load torque by using the disturbance torque estimation unit to estimate the disturbance torque according to the speed command. A servo amplifier with: A speed control unit that generates a torque command of the motor based on a speed command of the motor that causes the movable part to move in a movement direction having a vertical direction component; A torque control unit, which controls the torque of the motor according to the torque command; A load torque estimation unit, which estimates the load torque borne by the motor according to the speed command; and The output unit outputs information related to the load torque estimated by the load torque estimation unit to the outside of the servo amplifier. The servo amplifier according to any one of claims 1 to 7, wherein The output unit performs peak hold on the estimated value of the load torque, and transmits the peak hold value of the estimated value to the outside of the servo amplifier. The servo amplifier according to claim 8, wherein The output unit resets the peak hold value every time the peak hold value is sent to the outside of the servo amplifier, and performs peak hold on the estimated value of the load torque again. The servo amplifier according to any one of claims 1 to 7, wherein The output unit time-integrates the estimated value of the load torque, and sends the time-integrated value of the estimated value to the outside of the servo amplifier. The servo amplifier according to any one of claims 1 to 10, wherein: The load torque estimation unit estimates the load torque during the pressing operation of the movable portion. A servo system includes a servo amplifier and an external device provided outside the servo amplifier, wherein, The servo amplifier has: A torque control unit, which controls the torque of the motor based on a torque command of the motor that causes the movable unit to move in a movement direction having a vertical direction component; A disturbance torque estimation unit, which estimates the disturbance torque borne by the motor; The load torque estimation unit subtracts the gravitational torque generated by the gravity acting on the movable portion from the disturbance torque estimated by the disturbance torque estimation unit, thereby applying the load to the motor To estimate the load torque; and The output unit outputs information related to the load torque estimated by the load torque estimation unit to the outside of the servo amplifier. A servo system includes a servo amplifier and an external device provided outside the servo amplifier, wherein, The servo amplifier has: A speed control unit that generates a torque command of the motor based on a speed command of the motor that causes the movable part to move in a movement direction having a vertical direction component; A torque control unit, which controls the torque of the motor according to the torque command; A load torque estimation unit, which estimates the load torque borne by the motor according to the speed command; and The output unit outputs information related to the load torque estimated by the load torque estimation unit to the outside of the servo amplifier.

Images