JPH11313495A - Controller for motor servo system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for motor servo system, which has such an auto-tuning function that ca easily and surely set the convergence of control gains. SOLUTION: A controller for motor servo system is provided with a disturbance estimating observer 8, which outputs an estimated disturbance torque value and acceleration information by using a current command and speed information obtained from a motor servo system, an inertia estimator 9 which outputs an estimated inertia value by the use of the estimated disturbance torque value and acceleration information, and a gain adjuster 28 which adjusts the gain of the speed control section 6 of the motor servo system to an appropriate value by using the estimated inertia value. The controller finds the estimated inertia value by multiplying the estimated disturbance torque vale by acceleration in the inertia estimator 9 and making the estimator 9 make integrating operations during one period or performing filtering processing, after the estimated disturbance torque value is multiplied by the acceleration in the estimator 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a motor servo system for driving a mechanical system, and more particularly to a control device for a motor servo system having an auto-tuning function capable of automatically setting a control gain.

[0002]

2. Description of the Related Art A conventional motor servo control device is adjusted according to the size of the mechanical system and the state of vibration when the control device is first installed or when the characteristics of the mechanical system change due to aging. The operator had to reset the gain. In order to solve such a drawback, Japanese Patent Laid-Open No. 4-325886 proposes a motor servo control device capable of automatically setting the size of the motor and the inerter or the gain suitable for the size of the motor and the inertia and the vibration of the mechanical system. ing.

[0003] Such a prior art example will be described with reference to the drawings. FIG. 5 shows the configuration of a motor servo system control device of the prior art, 30a is a motor servo system controller with an auto tuning function, 31 is a servo system simulation unit, and the simulation unit 31 is configured as follows. ing. That is, 1b is an electric motor in a simulation, a mechanical system model, 5b is a current control unit in the simulation, 6b is a speed control unit in the simulation, 7b is a position control unit in the simulation, 12b is a position detection value in the simulation, 1
3b is a speed detection value in the simulation, 14b is a current detection value in the simulation, 15b is a position error in the simulation, 16b is a speed command value in the simulation, 17b is a speed error in the simulation, 18b is a current command value in the simulation, and 19b is a current command value in the simulation. Current error,
20b is the motor current in the simulation.

A current area calculation unit 21 calculates and compares respective current areas from the actual current detection value 14 and a current detection value 14b in the simulation. 22 denotes a current area calculation unit based on the calculation results of the current area calculation unit 21. An inertia correction amount determination unit that determines the correction amount of the assumed inertia value of the electric motor / mechanical system model 1b, and 23 is a gain determination unit that determines the optimal gain of the speed control units 6 and 6b for the corrected assumed inertia value. .

In FIG. 1, reference numeral 1 denotes an electric motor, 2 denotes a mechanical system attached to the electric motor 1, and a combination of the electric motor 1 and the mechanical system 2 is an object to be controlled. 3 is a position and speed detector for measuring the position and speed of the control targets 1 and 2, 4 is a current detector for measuring the current flowing through the motor 1, 5 is a current controller, 6 is a speed controller, 7 is a position controller. , 11 are position command values, 12 is position detection values, 13 is speed detection values, 14 is current detection values, 15
Is a position error, 16 is a speed command value, 17 is a speed error, 18
Is a current command value, 19 is a current error, 20 is a current flowing through the motor 1, and 30a is a motor servo system controller.

Next, the operation will be described. First, the operation of the motor servo system will be described. The electric motor servo system controller 30a is for performing trajectory control on, for example, a machine tool or a robot, and generates a position command value 11 from a desired trajectory command value. It is for operating according to.
That is, the difference between the position detection value 12 obtained by the detector 3 and the position command value 11 is calculated to obtain a position error 15, and the position control unit 7 performs an appropriate calculation to obtain the speed command value 16.
To determine.

Next, the difference between the speed detection value 13 obtained by the detector 3 and the speed command value 16 is calculated, and the speed error 17 is calculated.
And the speed control unit 6 performs an appropriate calculation to determine the current command value 18. Further, the difference between the current detection value 14 obtained by the current detector 4 and the current command value 18 is calculated to obtain a current error 19, and the current control unit 5 performs an appropriate calculation to determine the motor current 20.

In the above-described conventional apparatus, the position control unit 7, the speed control unit 6, and the current control unit 5 perform P (proportional) operation and PI (proportional / integral) operation, respectively. By using an appropriate gain according to the control targets 1 and 2 in each calculation of the control units 5 to 7, good trajectory control can be realized.

If the characteristics of the motor 1, the detectors 3, 4 are known in advance, and only the characteristics of the mechanical system 2 are unknown, all parameters in the current loop are known, and the current control unit The gain of 5 can be determined in advance from these parameters. When a plurality of electric motors are operated at the same time as in a machine tool, the response frequency of the position loop needs to be matched, so that the gain of the position control unit 7 uses a predetermined value.

Therefore, in this prior art, only the automatic adjustment of the proportional gain and the integral gain of the speed control unit 6 is performed. However, automatic setting of the gain of the position control unit 7 according to the speed loop response frequency can be realized by a simple extension of this embodiment.

On the other hand, in the servo system simulation unit 31, the current control unit 5b, the speed control unit 6b and the position control unit 7b are respectively connected to the current control unit 5, the speed control unit 6 and the position control unit 7 in the actual servo system. Are the same. The electric motor / mechanical system model 1b is a model of the control targets 1 and 2 and the detectors 3 and 4, and in this model, the mechanical system 2 is assumed to have a simple inertia without considering mechanical vibrations and the like. As described above, since the characteristic parameters of the electric motor 1 and the detectors 3 and 4 are clear, in the electric motor / mechanical system model 1b, only the magnitude of the inertia including the electric motor 1 and the mechanical system 2 becomes an unknown parameter. The assumed value is J.

In this conventional example, the current detection values 14 and 14b when the same position command value 11 is added to the actual servo system and its simulation unit 31 are compared, and the assumed inertia value J is corrected according to the comparison result. Finally, a fixed value of inertia and an optimum loop gain are obtained.

[0013]

The auto-tuning function of the conventional motor servo control device is constructed as described above, and integrates the actual current with time and compares it with the current integrated value of a virtual model in the control device. Since the gain is sequentially adjusted so that the two coincide with each other, it takes time to converge. In addition, there is a problem that the convergence is not guaranteed.

An object of the present invention is to provide a control device for an electric motor servo system having an auto-tuning function capable of solving such a problem, particularly, easily and reliably setting the convergence of the control gain.

[0015]

According to a first aspect of the present invention, there is provided a method for calculating a disturbance torque estimated value and acceleration information using a current command obtained from an electric motor servo system and the speed information. A disturbance estimation observer to be output, an inertia estimator that outputs an inertia estimation value using the disturbance torque estimation value and the acceleration information obtained from the disturbance estimation observer, and a speed control of a motor servo system using the inertia estimation value. A gain adjuster that adjusts the gain of the section to an appropriate value, wherein in the inertia estimator, the product of the disturbance torque estimated value and the acceleration and the square value of the acceleration obtained by the speed command that is periodically output is obtained. It is characterized in that an integral value during a period is obtained, and an inertia estimated value is obtained through a quotient of the former integral value with respect to the latter integral value.

Further, according to a second aspect of the present invention, in the inertia estimator, a product of a disturbance torque estimated value and an acceleration obtained by a periodically output speed command and a square value of the acceleration are obtained. Is characterized by obtaining an inertia estimated value via a quotient obtained by the filtering process.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. However, unless otherwise specified, dimensions, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the invention, but are merely illustrative examples.

FIG. 1 is a block diagram showing the configuration of a control device for a motor servo system according to an embodiment of the present invention. Reference numeral 30 denotes a motor control device with an auto-tuning function.
To operate the mechanical system. Reference numeral 3 denotes a detector attached to one electric motor, which generates an original signal of 12 position information and 13 speed information. In the control device 30, the motor current 20 is detected by the detector 4 using the current signal 14.
The current controller 5 controls the motor current 20 using the difference 19 between the value and the current command value 18. The speed control unit 6 also calculates a difference 17 between the speed information 13 and the speed command value 16.
To output the current command value 18, and the position control unit 7 outputs the speed command value 16 using the difference 15 between the position information 12 and the position command value 11. Such a configuration is similar to that of the prior art shown in FIG.

Here, using the current command value 18 and the speed information 13, the disturbance estimation observer 8 outputs the disturbance torque estimation value 32 and the acceleration 34 as acceleration information to the inertia estimator 9 side. The inertia estimator 9 outputs an inertia estimated value 10 using the disturbance torque estimated value 32 and acceleration 34 as acceleration information. Gain adjuster 2
8 adjusts the gain of the speed control unit 6 of the electric motor servo system to an appropriate value using the estimated inertia value 10. Next, how to appropriately adjust the gain will be described.

First, the operation of the disturbance observer 8 will be described. The characteristics of the mechanical system (including when the motor is driven) targeted by the control device of the present invention are considered as follows. The mechanical system is a single inertial system in which a constant load torque, viscous resistance, and Coulomb friction act. This equation of motion is: Here J · dω / dt = T- Dω-Tc · sign (ω) -T L ... (1), J: inertia moment T: torque D: viscosity resistance coefficient Tc: Coulomb Friction size T _L: constant Load torque ω: angular velocity Sign (ω) is a sign function, and Sign (ω) = 1 (ω ≧ 0) Sign (ω) = − 1 (ω <0)

The generated torque T is expressed by the following equation which is linear with respect to the current command Ic. T = K _T · Ic (2) Here, K _T : torque constant ∴ Equation (1) becomes equation (3). J · dω / dt = K _T · Ic−Dω−Tc · sign (ω) −T _L (3) The disturbance observer 8 calculates the acceleration 34 from the change in the speed information 13 and multiplies the acceleration 34 by the reference inertia 26. Is used to estimate the generated torque 33. Then, the disturbance torque estimated value 32 is expressed by the following equation ("Equation 1").

(Equation 1) Here, ΔJ: reference inertia J ₀ and true inertia J
Value difference

Next, the operation of the inertia estimator 9 will be described. Assuming that the estimation time of the estimator 9 is sufficiently short, and that Td does not change in the section, dTd / dt = 0 (5) Equation (4) is obtained by using the state variables q _{0 to} q ₂ as follows. Represent.

(Equation 2) At this time, if the speed command r (t) is periodic, it has the following properties. r (t) = r (t−T ₀ ) (7) r (t) ≠ 0 (8) where T _{0 is the} cycle. Therefore, the acceleration 34 is applied to the estimated disturbance torque 32 shown in the equation (6). The following equation is obtained by multiplying and integrating for one cycle.

(Equation 3) Here, the following equation is established from the orthogonality of the periodic function.

(Equation 4) Therefore, the estimated inertia value 10 is given by the following equation.

(Equation 5) Here, when the value of the denominator of the second term of Expression (12) is minute, J
Is inaccurate, so if the value of the denominator is very small (1
The calculation of equation 2) is not performed.

Finally, the operation of the gain adjuster 28 will be described.
The open loop transfer function Gs (s) of the speed system is, for example, PI control
Can be expressed by the following equation. Gs (s) = (Ksp + Ksi / s) · KT / (Tcs + 1) J · s (13) where Ksp: speed loop proportional gain Ksi: speed loop
Loop integral gain K_T : Torque constant Tc: Current control delay
If the response of the current control system is fast enough, the intersection angular frequency ω
Tc = 0 near sc. Also, the break angle frequency of PI
The number ωpi is given by the following equation. ωpi = Ksi / Ksp (14) で は In the vicinity of ωsc, Ksp = J · ωsc / K_T  Therefore, by changing ωsc according to the rigidity, J can be given appropriately.
For example, the control of the speed control unit 6 is optimal.

FIG. 2 shows the configuration of a control device for an electric servo system according to a second embodiment of the present invention. However,
Although the internal configuration of the inertia estimating unit 9a is different, the configuration is basically the same as FIG. FIG. 3 shows a configuration of the inertia estimating unit 9a which is a feature of the present invention. In FIG. 3, the integral calculation shown in equation (12) in FIG. 1 is performed via a filter.

As shown in the drawing, the acceleration 34, which is acceleration information output from the disturbance estimation observer 8 in FIG. 2, and the disturbance torque estimated value 32 are input to the inertia estimating section 9a.
The inertia estimation value 10 is output.
First, a product 37 of the disturbance torque estimated value 32 and the acceleration 34 is calculated via a mixer 35, and the calculated value 37 is further calculated.
By a filter 39 having a delay time T _CAL as a time constant,
An arithmetic processing is performed to obtain an arithmetic value A.

On the other hand, the acceleration 34
Is calculated, and the calculated value 38 is further converted to a delay time T
_The arithmetic processing is performed by a filter 39 using _CAL as a time constant to obtain an arithmetic value B. Next, A / B arithmetic processing is performed by the division unit 40 to obtain ΔJ shown in the second term on the right side of Expression (12), and the reference inertia J ₀ is further added by the addition unit 41 to obtain the estimated inertia value 10. Thus, the signal is input to the gain adjuster 28.

According to the present embodiment, since the integration operation is substituted by the filter processing, the implementation is easy, the operation can be performed at high speed without performing complicated calculations, and the real-time can be realized by appropriately selecting the filter time constant. It can be implemented in. It can also be mounted on devices with strict restrictions such as one-chip microcomputers.

Therefore, it can be understood that in each of the above embodiments, the identification is completed in one cycle and the gain is appropriately adjusted as shown in FIG.

[0029]

The present invention has the following effects as compared with the prior art shown in FIG. 1) Although the conventional tuning method shown in FIG. 5 sequentially changes the inertia and adaptively identifies the inertia, the present invention can identify the true inertia in one cycle in principle in the present invention. 2) In the present invention, the orthogonality of the periodic function is used for the derivation of inertia, and it has been proved that there is a problem that the conventional method does not converge, but it can always be derived. 3) In the prior art, the gain is adjusted after oscillation, but in the present invention, an appropriate tuning can be performed from the beginning by setting in advance a band corresponding to the rigidity. 4) In particular, in the invention according to the second aspect, since complicated processing is not required, it can be realized even in an embedded device such as a one-chip microcomputer having strict restrictions.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a control device for an electric servo system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control device for an electric servo system according to a second embodiment of the present invention.
Is the same as

FIG. 3 is a diagram illustrating a configuration of an inertia estimating unit according to a second embodiment of the present invention.

FIG. 4 is a waveform diagram showing a state of identification of a motor speed and a current command value after the start of auto tuning.

FIG. 5 is a diagram illustrating a configuration of a control device for a motor servo system according to the related art.

[Explanation of symbols]

 5 Current control unit 6 Speed control unit 7 Position control unit 8 Disturbance estimation observer 9 Inertia estimator 28 Gain adjuster

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Ichirou Awaya 1-1-1, Wadazakicho, Hyogo-ku, Kobe-shi Inside the Kobe Shipyard, Mitsubishi Heavy Industries, Ltd.

Claims (2)

[Claims] 1. A disturbance estimation observer for outputting a disturbance torque estimation value and acceleration information using a current command obtained from an electric motor servo system and the speed information, and the disturbance torque estimation obtained from the disturbance estimation observer. An inertia estimator that outputs an estimated inertia value using the value and the acceleration information; and a gain adjuster that adjusts a gain of a speed control unit of the electric motor servo system to an appropriate value using the estimated inertia value. In the estimator, the integral value between one cycle of the product of the disturbance torque estimated value obtained by the speed command output periodically and the acceleration and the square value of the acceleration is obtained, and the integral value of the former integral value with respect to the latter integral value is obtained. A control device for an electric motor servo system, wherein an estimated value of inertia is obtained via a quotient. 2. A disturbance estimation observer for outputting a disturbance torque estimation value and acceleration information using a current command obtained from an electric motor servo system and the speed information, and the disturbance torque estimation obtained from the disturbance estimation observer. An inertia estimator that outputs an estimated inertia value using the value and the acceleration information; and a gain adjuster that adjusts a gain of a speed control unit of the electric motor servo system to an appropriate value using the estimated inertia value. In the estimator, the product of the disturbance torque estimated value obtained by the speed command output periodically and the acceleration and the square value of the acceleration are obtained, and the inertia estimation is performed through the quotient obtained by filtering both. A control device for an electric motor servo system, which obtains a value.