JPH0380311A - Disturbance torque compensator - Google Patents

Abstract

PURPOSE:To suppress rock and vibration of a driving part caused by the characteristic of a current compensating system by calculating a nominal torque from the output current value of a cancel part. CONSTITUTION:A cancel part 158 is provided between a current detecting part 138 and a nominal torque arithmetic part 148 in order to suppress the current fluctuation and the shake/vibration of a drive part caused by the influence of a current compensating system. The part 158 has the adverse characteristic 1/Gci of the characteristic Gci and therefore the current value inputted to the part 148 is free from the influence of the system 146. In addition, an impulse current eliminating filter 160 having a time constant equal to that of a noise eliminating filter 152 is provided between a speed compensator 130 and a joint point 132. In such a constitution, the current fluctuation due to the influence of the system 146 and the rock and the vibration due to the current fluctuation can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a disturbance torque compensator, and particularly to an improvement of a disturbance torque compensator using a disturbance torque observer.

[Prior Art] In recent years, there has been a strong demand for drive devices that accurately control the movement of movable parts in various machine tools, X-Y tables, measuring instruments, etc. for extremely high-precision machining or measurement. Such a drive device conventionally uses a drive unit such as a motor to move a movable part (for example, a table, a measurement probe, etc.) connected to the drive force transmission unit via a drive force transmission unit such as a ball screw in a predetermined manner. There are many things under control.

FIG. 7 shows a schematic diagram of such a general drive device. Although the drive device shown in the figure should originally be discussed as a two-shaft system or a three-wheel system, for convenience of explanation, a -shaft system is shown.

In the figure, a drive device 10 includes a movable section 12 and a drive section 14.
, a driving force transmission section 16.

The movable part 12 is composed of, for example, an X-Y table.

Further, the drive unit 14 is composed of a motor 18 and a motor driver 20 that drives the motor 18.

Further, the driving force transmitting section 16 includes a ball screw 24 connected to the rotating shaft of the motor 18 via bearings 22 a and 22 b. The ball screw 24 has a movable part 1 such as a table that changes the relative position by rotation of the ball screw 24.
2 are screwed together.

Incidentally, in the drive device as described above, various types of feedback compensation as shown in FIG. 8 are generally employed, and accurate current supply, speed control, and positioning control are performed.

That is, the DC motor 18 is controlled by the position controller 26 at the summing point 28, the speed compensator 30. It is driven by a summing point 32, a current compensator 34, and a driver 36.

Further, the driving force transmitting section 16 applies a driving amount to the movable section 12 according to a predetermined driving force transmitting characteristic.

Here, the position control section 26 includes a counter 26a1, a position controller 26b, and a D/A converter 26c.

A current detector 38 is provided at the subsequent stage (output end) of the driver 36, and current feedback is performed by a negative signal to the summing point 32.

Further, the rotation of the DC motor 18 is subjected to speed feedback via a tachometer 4° to a summing point 28 by a negative signal.

Furthermore, the movement of the movable part 12 based on the drive of the DC motor 18 provides position feedback to the counter 26a of the position control part 26 as a scale signal (position signal) of the scale 42. This position control section 26 performs position control processing using software using a microcomputer or the like.
Hardware speed control using summing point 28, speed compensator 30, summing point 32, current compensator 34 and driver 36,
Current control is performed, and drive control is performed by these software processing and hardware processing.

To briefly explain such a servo system, first, a desired movement of the movable part 12 is set by the position control section 26, and the DC motor 18 is driven by the driver 36 according to the set amount.

Then, the current detection section 38 detects whether or not the DC motor 18 is driven by a predetermined current, and the detected amount is fed back to the summing point 32 as a negative signal, and the current compensator 34 outputs the current to the DC motor 18. Compensation is made to supply the desired current.

Further, the rotation of the DC motor 18 is detected by a tachometer 40, and the detected amount is fed back as a negative signal to the addition point 28, and the speed compensator 30 compensates for the DC motor 18 to rotate at a predetermined speed. ing.

Furthermore, the position of the movable part 12 is detected by the scale 42, and the counter 26 of the position control part 26 is detected as a scale signal.
a, the drive amount is corrected by the position controller 26b, and the position of the movable part 12 is controlled via the D/A converter 26c.

FIG. 9 shows the main parts of the physical system of such a drive device.

In the same figure, the characteristics due to the speed feedback system are Gv
The characteristic due to current feedback is shown as Gi. Then, the target angular velocity ω0 is corrected using the characteristic Gv to obtain a target current value 11, and the target current value i1 is further corrected by current feedback using the characteristic Gv. Further, after being amplified by the driver 36 with a characteristic of 1/(Rs+L), it is supplied to the motor 18 as an actual armature current i.

Note that when the motor 18 rotates, a back electromotive force eb is generated due to the characteristic Ke based on the load.

As described above, when the armature current i is supplied to the motor 18, a motor torque T is obtained according to the torque constant of the motor 18. On the other hand, a moment of inertia J exists in the movable portion 12 and the driving force transmission portion 16, and the rotational angular velocity ω of the rotor is expressed by the following equation.

ω=(Kl/JS)・i...(1) Furthermore,
In the above formula (1), S is a differential operator.

However, a disturbance torque TL is applied to the physical system of such a motor. Further, the torque constant K ts and the moment of inertia J also fluctuate, and if this continues, it is not possible to obtain an accurate and stable rotational angular velocity ω of the motor. In this regard, the various feedback systems mentioned above are completely powerless.

Therefore, when applying these disturbance torques TL, the torque constant becomes 1.
, to remove the influence of fluctuations in the moment of inertia J, the first
A feedforward compensation method using a disturbance torque observer as shown in Fig. 0 has been considered.

That is, the armature current i is detected, and the armature current i is multiplied by the nominal value K I m of the torque constant.

On the other hand, the rotational angular velocity ω of the rotor is detected, and J
, s (J is the nominal value of the moment of inertia).

Then, the nominal torque level obtained from the armature current and the nominal torque level obtained from the rotational angular velocity are compared, and the difference value is set as the estimated disturbance torque value TL.

Here, the estimated disturbance torque value TL' is expressed by the following equation.

TL=JiS・ω−0・i... (2) Therefore, the torque constant is = □moment of inertia) J=J, then the estimated disturbance torque value is as shown in the following equation. T,=T,
becomes.

TL'=Jfis・ω−, 1l−1=J n s・ω−T=TL...(3
) and 1/K to this estimated disturbance torque value TL'.

By multiplying by , a current value iTL corresponding to the disturbance torque is obtained, and the converted current value ILL is subtracted from the current target value i'''.

At this time, the rotational angular velocity ω of the rotor is expressed by the following equation.

Therefore, if the feedforward compensation system using the disturbance torque observer as described above can be obtained in an ideal state, it will be possible to obtain a motor output that is not affected by disturbance torque or the like.

[Problems to be Solved by the Invention] However, upon further study by the present inventor, it was found that the torque compensation system shown in FIG. was discovered.

In other words, the current compensation system performs feedback compensation of the current based on predetermined characteristic values, but the effect of this compensation system causes minute waves in the actual current, which also causes a subtle effect on the angular velocity ω. It is.

This is explained as follows.

In FIG. 10, considering the characteristic Get of the current compensation system (characteristic including compensation of back electromotive force), the relationship between ω, i*, and TL is expressed by the following equation.

■ X (i”-(1/Gci-1)TL/,] ・
... (5) Here, if Gci=1, the above (5)
The formula becomes, and it has ideal characteristics.

However, in reality, Gci has dynamic characteristics, so the above (5
) In the equation (1/Gci-1)J s/, the influence of fluctuations in J or Kt appears in the term.

Furthermore, it is understood that the influence of TL appears in the term (1/Gci-1)TL/.

Of course, the same thing can be expected with respect to the actual current i, and as a result, the characteristic Gci of the current compensation system becomes a cause of fluctuations and vibrations.

The present invention has been made in view of the problems of the prior art described above, and its purpose is to provide a disturbance torque compensator capable of suppressing current fluctuations caused by the influence of a current compensation system, as well as vibrations and fluctuations based on the fluctuations. .

[Means for Solving the Problem] In order to achieve the above object, the disturbance torque compensator according to claim 1 of the present application includes a current detection section, a cancellation section,
a nominal torque calculation section, a speed detection section, an acceleration calculation section, a disturbance torque calculation section, a disturbance torque/current conversion section,
including.

The current detection section detects the current supplied to the drive section.

The canceling unit applies an inverse characteristic that cancels the current compensation characteristic of the current compensation system to the detected current value.

The nominal torque calculating section calculates the nominal torque from the output current value of the canceling section.

The speed detection section detects the driving speed of the drive section.

The acceleration calculating section differentiates the driving speed of the driving section and calculates the nominal acceleration.

The disturbance torque calculation section calculates the disturbance torque from the difference value between the nominal acceleration and the nominal torque.

The disturbance torque/current converter converts the disturbance torque amount into a current value.

Further, the disturbance torque compensator according to claim 2 of the present application includes:
The present invention is characterized in that it includes a current detection section that detects a current from a connection point between the drive current supply system and the current compensation system.

[Operation] Since the disturbance torque compensating device according to the present invention has the above-described means, the driving speed detected by the speed detecting section is differentiated by the acceleration calculating section to obtain the nominal acceleration.

On the other hand, the drive current supply system supplies drive current to the drive unit via the current compensation system, and the current detection unit detects the supplied current. However, the current value detected by the current detection section is not directly sent to the nominal torque calculation section, but is passed through the cancellation section. Here, the cancellation section adds a characteristic opposite to the characteristic added by the current compensation system to the detected current value.

Therefore, the influence of the current compensation system is excluded from the disturbance torque compensation system, and minute waves of the drive current and shaking and vibration of the drive unit are suppressed.

On the other hand, according to the disturbance torque compensator according to claim 2 of the present application, since the current is detected between the drive current supply system and the current compensation system, the influence of the current compensation system does not interfere with the disturbance torque compensation system. . As a result, it becomes possible to suppress fine waves of the drive current, vibrations and vibrations of the drive section, as in the invention according to claim 1 above.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a block diagram showing a schematic configuration of a disturbance torque compensator according to the present invention, and portions corresponding to those in FIG.

Similar to FIG. 8, the drive device shown in FIG.
A movable part 11 that receives a driving force from 6 and performs a predetermined movement.
2.

A current compensation system 146 is configured by a loop formed by the current compensator 134, the driver 136, the current detection section 138, and the summing point 132. Note that in FIG. 9, compensation for the back electromotive voltage eb is performed all at once by the current compensation system 146 (the characteristic of the current compensation system at this time is assumed to be Get).

In order to cope with the occurrence of disturbance torque or fluctuations in the load on the movable part 112, the following disturbance torque compensation system is provided.

That is, in this embodiment, in addition to the current detection section 138, there is a nominal torque calculation section 148, a differentiator 150ε as an acceleration calculation section, a noise removal filter 152, a disturbance torque calculation section 154, and a disturbance torque/current conversion section 156.
and.

The nominal torque calculation unit 148 receives the detection result of the current supplied to the DC motor 118 from the current detection unit 138, and calculates a nominal torque value from the detected current value.

On the other hand, the differentiator 150 detects the motor 1 from the tachometer 140.
The rotational angular velocity ω of 18 is input, and the velocity value is differentiated to calculate the acceleration value.

A noise removal filter 152 is connected to the output terminal of the differentiator 150 and removes noise caused by the differential action of the differentiator 150.

Further, the disturbance torque calculation section 154 is composed of a summing point, and receives ten outputs from the filter 152 and one input from the nominal torque calculation section 148.

The addition result is input to the current converter 156,
The disturbance torque/current is converted and input to the addition point 132.

A feature of the present invention is that a canceling section 158 is provided between the current detecting section 138 and the nominal torque calculating section 148 in order to suppress current fluctuations, fluctuations, and vibrations caused by the influence of the current compensation system.

Here, the canceling unit 158 has a characteristic 1/Gci that is the opposite of the characteristic Gci of the current compensation system 146.

Therefore, the current value input to the nominal torque calculation unit 148 has the influence of the current compensation system 146 removed.

Furthermore, in this embodiment, in order to avoid the generation of impulse current, an impulse current avoidance filter 158 having the same time constant τ as the noise removal filter 152 is inserted between the speed compensator 130 and the summing point 132. .

Next, the operation of the present invention will be explained with reference to FIG. FIG. 2 shows the physical system of the block diagram shown in FIG.

As is clear from the figure, the basic configuration is the same as that shown in FIG. 6 above.

However, in this embodiment, as is clear from the above-mentioned engineering drawing, the canceling section 158 is provided, so the detected current i is multiplied by the characteristic 1/Get, and current compensation is performed when calculating the nominal torque. The influence of the characteristic Gci of the system 146 is canceled.

Therefore, according to the disturbance torque compensation system according to this embodiment,
Shaking and vibration based on the characteristic Gci of the current compensation system can be reliably suppressed.

Note that in this embodiment, the impulse current avoidance filter 160
is inserted, the target current value 11 in FIG. 2 is filtered by 1/(1+τS).

As a result, the following advantages can be obtained.

As mentioned above, in the actual implementation of the disturbance torque observer, it is necessary to add the filter 152 shown in FIG.

That is, after detecting the rotational angular velocity ω, the acceleration is obtained by a differential operator S in order to convert it into a torque level.

However, differential processing usually involves a lot of noise, so a filter must be used.

Therefore, in FIG. 2, τ·S is added, and the differentiation process is performed as a whole using the following equation.

In5 (7) 1+τS Note that τ is the time constant of the filter.

As a result, in the implementation mode, the armature current i and the zero rotation angular velocity ω are each expressed by the following equations.

Therefore, due to the influence of the differential term of τ·S, when a step-like command is added to the current value 10, an impulse-like current is required as the actual current.

Physically, this means that an infinite amount of current is instantaneously drained, and an extremely large negative t is added to the current supply system.

Therefore, in this embodiment, an impulse current shielding filter 160 is provided.

As a result, the above equations (8) and (9) are converted into the following equations.

K, i” =-・□ ... (11)
a s As mentioned above, the actual current i is not affected by the differential term τS,
Even when a step-like command is added to the target current value 11, an impulse-like current is not required as the actual current i.

Moreover, the relationship of ω-19 is also in an ideal state, and extremely excellent load unresponsiveness is maintained.

FIG. 3 shows a block diagram of a disturbance torque compensator according to a second embodiment of the present invention, and portions corresponding to those in FIG.

The characteristic feature of this embodiment is that instead of providing a canceling section as in the first embodiment, the first current detecting section 262 that detects the current value to be input to the nominal torque calculating section 248 is compensated for by current compensation. This is because it is provided before the system 246.

Note that the current compensation system 246 is provided with a second current detection section 238 for current compensation.

The physical system of the disturbance torque compensator configured as described above is shown in FIG.

As is clear from the figure, the influence of the characteristic Gci of the current compensation system does not intervene in the nominal torque calculation at all, and stable current characteristics similar to those of the first embodiment are obtained, and vibrations and vibrations of the drive section are suppressed. can be carried out.

Next, with reference to FIGS. 5 and 6, the effects of the disturbance torque compensator according to this embodiment will be explained.

FIG. 5 shows the relationship between the actual current i and the angular velocity ω when the drive device is started while applying a disturbance torque (indicated by a broken line in the figure) at a constant period in a conventional device that does not include the cancellation section.

Furthermore, FIG. 6 shows the actual current i under the same conditions as in FIG. It shows the relationship between angular velocity ω and angular velocity ω.

As is clear from FIG. 5, when the canceling section 158 is not provided, the actual current i draws minute waves under the influence of the current compensation system, and this tendency occurs every time the disturbance torque is compensated. Furthermore, the angular velocity ω also shows minute fluctuations and vibrations, and it is understood that an accurate and stable driving state is not obtained.

On the other hand, although FIG. 6 shows that the current i increases and decreases in accordance with the disturbance torque, it does not depict minute waves as seen in FIG. 5. Of course, the angular velocity ω also reaches a constant line with a smooth curve, and there are very few fluctuations or vibrations after that.

As described above, according to the disturbance torque compensator according to the present embodiment, a constant driving state can be stably obtained despite the application of disturbance torque, and good angle t# non-reactivity can be achieved. be able to. In particular, the device according to this embodiment has good responsiveness and can suppress vibrations and the like without time delay.

[Effects of the Invention] As explained above, according to the disturbance torque compensator according to the invention set forth in claim 1 of the present application, the detection current is provided with a canceling section that cancels the current compensation characteristic of the current compensation system, and the Since the nominal torque is calculated from the output current value of the canceling section, it is possible to suppress vibrations and vibrations of the driving section based on the characteristics of the current compensation system.

Further, according to the disturbance torque compensator according to the invention set forth in claim 2 of the present application, a current is detected from a connection point between the drive current supply system and the current compensation system, and a nominal torque is calculated from the detected current value. Therefore, with a simple configuration, it is possible to suppress vibrations and vibrations of the drive unit based on the characteristics of the current compensation system without any time delay.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a disturbance torque compensator according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the physical system of the disturbance torque compensator shown in FIG. 1, and FIG. A block diagram showing the configuration of a disturbance torque compensator according to a second embodiment of the invention, FIG. 4 is an explanatory diagram of the physical system of the disturbance torque compensator shown in FIG. 3, and FIG. An explanatory diagram showing the relationship between disturbance torque, current value, and angular velocity when a canceling section is not provided in the disturbance torque compensator shown in FIG. Fig. 7 is an explanatory diagram of a general drive device, Fig. 8 is a block diagram showing the feedback compensation system of a general drive device, and Fig. 9 is the same as shown in Fig. 8. An explanatory diagram of the main parts of the physical system of the drive device, FIG. 10 is an explanatory diagram of an ideal disturbance torque compensation system. 18.118,218...Motor (drive unit) 148.
246...Current compensation system 148.248...Nominal torque calculation unit 150.2
50...Differentiator (acceleration calculation section) 154.254...
・Disturbance torque calculation unit 156.256...Disturbance torque/
Current converter 158...Cancel unit 138,262...Current detector

Claims (2)

[Claims] (1) A drive current supply system that supplies a drive current to the drive unit; and a current compensation system that detects the actual drive current supplied to the drive unit and compensates it by feedback to a target current value, and has a predetermined current value. A disturbance torque compensator for a drive device driven by inputting a drive current includes a current detection unit that detects the current supplied to the drive unit, and a current compensation characteristic of a current compensation system added to the current value detected by the current detection unit. a canceling section for canceling, a nominal torque calculating section for calculating nominal torque from the output current value of the canceling section, a speed detecting section for detecting the driving speed of the driving section, and differentiating the driving speed of the driving section,
an acceleration calculation unit that calculates a nominal acceleration; a disturbance torque calculation unit that calculates a disturbance torque from a difference value between the nominal acceleration and the nominal torque; and a disturbance torque/current conversion unit that converts the disturbance torque amount into a current value; A disturbance torque compensator comprising: (2) A drive current supply system that supplies a drive current to the drive unit; and a current compensation system that detects the actual drive current supplied to the drive unit and compensates it by feedback to a target current value, and has a predetermined current value. A disturbance torque compensator for a drive device driven by inputting a drive current includes a current detection section that detects a current from a connection point between the drive current supply system and the current compensation system, and a nominal current value detected by the current detection section. a nominal torque calculation unit that calculates torque; a speed detection unit that detects the drive speed of the drive unit; an acceleration calculation unit that differentiates the drive speed of the drive unit and calculates nominal acceleration; and the nominal acceleration and nominal torque. A disturbance torque compensator comprising: a disturbance torque calculation unit that calculates a disturbance torque from a difference value; and a disturbance torque/current conversion unit that converts the disturbance torque amount into a current value.