JPH087624B2 - Disturbance torque compensator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a disturbance torque compensator, and more particularly to an improvement of the disturbance torque compensator using a disturbance torque observer.

[Prior Art] In recent years, for machine tools, XY tables, measuring instruments and the like, a drive device for accurately moving and controlling a movable part has been strongly demanded for extremely highly accurate machining or measurement. As such a driving device, a movable portion (eg, a table, a measurement probe, etc.) connected to a driving force transmitting portion such as a ball screw or the like from a driving portion such as a conventional motor is conventionally used.
In many cases, the movement control is performed in a predetermined manner.

FIG. 7 shows a schematic view of such a general driving device. The drive device shown in the figure is originally a biaxial system,
Although it should be discussed in the triaxial system, a uniaxial system is shown for convenience of explanation.

In the figure, the driving device 10 is composed of a movable portion 12, a driving portion 14, and a driving force transmission portion 16.

 The movable part 12 is composed of, for example, an XY table.

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

Further, the driving force transmission unit 16 is composed of a ball screw 24 connected to the rotating shaft of the motor 18 via bearings 22a and 22b. The ball screw 24 is screwed with a movable portion 12 such as a table whose relative position is changed by its rotation.

By the way, in the drive apparatus as described above, various kinds of feedback compensation as shown in FIG. 8 are generally adopted, and accurate current supply, speed control, and positioning control are performed.

That is, the DC motor 18 is added by the position control unit 26
It is driven by 28, speed compensator 30, addition point 32, current compensator 34, and driver 36.

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

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

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

Further, the rotation of the DC motor 18 is added to the addition point 28 via the tachometer 40, and speed feedback is performed by a negative signal.

Further, the movement of the movable portion 12 based on the drive of the DC motor 18 is performed as a scale signal (position signal) of the scale 42 by the position control portion.
Position feedback is performed to the counter 26a of 26. The position control unit 26 performs position control processing by software using a microcomputer or the like, and the addition point 2
8, speed compensator 30, adding point 32, current compensator 34 and driver 36 to perform speed control and current control in hardware,
Drive control is performed by these soft processing and hardware processing.

The servo system will be briefly described. First, the position control unit 26 sets a desired motion of the movable unit 12, and the driver 36 drives the DC motor 18 according to the set amount.

Then, the current detection unit 38 detects whether or not the DC motor 18 is driven by a predetermined current, and the detected amount is added back to the combining point 32 as a negative signal,
The current compensator 34 compensates for supplying a desired current to the DC motor 18.

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

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

FIG. 9 shows the main part of the physical system of such a drive unit.

In the figure, the characteristic of the velocity feedback system is Gv.
, And the characteristic due to the current feedback is indicated by Gi. Then, the characteristics Gv correction made to the desired angular velocity omega ^*, to obtain a target current value i ^*, further correction characteristic Gv by a current feedback to the target current value i ^*
Is done in. Furthermore, the amplification by the driver 36 is characteristic 1 /
After being performed with (Rs + L), it is supplied to the motor 18 as an actual armature current i.

When the motor 18 rotates, the characteristics are
The counter electromotive voltage eb is generated by Ke.

When the armature current i is supplied to the motor 18 as described above, the motor torque T _m is obtained according to the torque constant K _t of the motor 18. On the other hand, the movable portion 12 and the driving force transmission portion 16
Has an inertia moment J, and the rotational angular velocity ω of the rotor is
Is represented by the following equation.

ω = (K _t / Js) · i (1) In the above formula (1), s is a differential operator.

However, the disturbance torque T _L is applied to the physical system of such a motor. Further, the torque constant K _t and the inertia moment J also fluctuate, and it is impossible to obtain an accurate and stable rotation angular velocity ω of the motor as it is. In this respect, the various feedback systems are completely useless.

Therefore, application of these disturbance torque T _L , torque constant K _t ,
In order to eliminate the influence of the fluctuation of the inertia moment J, a feedforward compensation method using a disturbance torque observer as shown in FIG. 10 has been considered.

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

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

Then, the nominal torque level obtained from the armature current is compared with the nominal torque level obtained from the rotational angular velocity, and the difference value is set as the disturbance torque estimated value T _L ′.

Here, the disturbance torque estimated value T _L ′ is represented by the following equation.

T _L ′ = J _n s · ω−K _tn · i (2) Therefore, the torque constant K _t = K _tn and the moment of inertia J = J _n
Then, the disturbance torque estimated value T _L ′ ＝ T _L
Becomes

T _L ′ = J _n s · ω − K _tn · i = J _n s · ω − T _m = T _L (3) Then, the disturbance torque estimated value T _L ′ is multiplied by 1 / K _tn to generate the disturbance. The current value i _TL corresponding to the torque is obtained, and the converted current value I _TL 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 with the above disturbance torque observer is obtained in an ideal state,
It is possible to obtain a motor output that is not affected by disturbance torque or the like.

[Problems to be Solved by the Invention] However, as a result of further study by the present inventor, the torque compensation system shown in FIG. 10 has a problem that vibration or vibration is generated during operation due to the influence of the current compensation system. Was found.

That is, in the current compensation system, current feedback compensation is performed based on a predetermined characteristic value, but a minute wave is generated in the actual current due to the influence of this compensation system, and the angular velocity ω
There is also a subtle effect.

 This is explained as follows.

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

Here, if Gci = 1, the above equation (5) becomes And will have ideal characteristics.

However, since actually Gci has dynamic characteristics, the formula (5) (1 / Gci-1) appears the effect of the variation of J or K _t is a term of Js / K _t.

In addition, it is understood that the influence of TL appears in the term of (1 / Gci-1) TL / K _t .

Of course, the same thing can be expected for the actual current i, and as a result, the characteristic Gci of the current compensation system causes fluctuation or vibration.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a disturbance torque compensator capable of suppressing current fluctuation due to the influence of a current compensation system, and fluctuation and vibration based on the fluctuation. .

[Means for Solving the Problem] In order to achieve the above object, a disturbance torque compensating device according to claim 1 of the present application is a drive current supply system, a current compensating system, a canceling unit, and an estimated drive torque calculation. A unit (hereinafter referred to as a nominal torque calculation unit), a speed detection unit, an acceleration calculation unit, a disturbance torque calculation unit, and a disturbance torque / current conversion unit.

Then, the drive current supply system supplies a drive current to the drive unit.

The current compensation system is a current detection unit that detects the actual drive current supplied to the drive unit, and a current that adjusts the drive current output so that the actual drive current output by the current detection unit matches the target current value. And a compensation unit.

The canceling unit is provided between the current detecting unit and the current compensating unit, and the current compensating characteristic Gci of the current compensating system added to the detected current value by the current detecting unit has a characteristic 1 / G.
Add ci to cancel.

The estimated drive torque calculation unit calculates an estimated drive torque (hereinafter, referred to as a nominal torque) from the output current value of the cancel unit.

 The speed detector detects the drive speed of the driver.

The acceleration calculator differentiates the drive speed of the drive unit to calculate a calculated acceleration (hereinafter, referred to as a nominal acceleration).

The disturbance torque calculation unit calculates the disturbance torque from a difference value between the torque obtained from the calculated acceleration and the estimated drive torque.

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

The disturbance torque compensator according to claim 2 of the present application is characterized by including a current detection unit 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 apparatus according to the present invention has the above-described means, the drive 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 a drive current to the drive unit via the current compensation system, and the supplied current is detected by the current detection unit. However, the current value detected by the current detection unit is not directly sent to the nominal torque calculation unit, but is passed through the cancellation unit. Here, in the canceling unit, the reverse characteristic of the characteristic added in the current compensation system is added to the detected current value.

Therefore, the influence of the current compensating system is excluded from the disturbance torque compensating system, and the minute wave of the driving current and the fluctuation and vibration of the driving unit are suppressed.

On the other hand, according to the disturbance torque compensator according to claim 2 of the present application, the current is detected between the drive current supply system and the current compensation system, so that the influence of the current compensation system does not intervene in the disturbance torque compensation system. . As a result, it becomes possible to suppress minute waves of the drive current, fluctuations of the drive section, and vibrations, as in the case of the first aspect of the invention.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a disturbance torque compensating device according to the present invention, and a portion corresponding to that in FIG.

Similar to FIG. 8, the drive device shown in the figure has a drive force transmission part 116 for transmitting the drive force of the DC motor 118 constituting the drive part via a ball screw or the like, and a drive force transmitted from the drive force transmission part 116. And a movable portion 112 which is transmitted to perform a predetermined motion.

Then, the current compensator 134, the driver 136, the current detection unit 13
8, the current compensation system 146 in the loop formed by the addition point 132
Is composed. In FIG. 9, the counter electromotive voltage eb
Is collectively performed by the current compensation system 146 (the characteristic of the current compensation system at this time is Gci).

Then, in order to cope with the generation of disturbance torque or the fluctuation of the load of the movable portion 112, the following disturbance torque compensation system is provided.

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

Then, the nominal torque calculation unit 148 inputs the detection result of the supply current to the DC motor 118 from the current detection unit 138, and calculates the nominal torque value from the detected current value.

On the other hand, the differentiator 150 inputs the rotational angular velocity ω of the motor 118 from the tachometer 140 and differentiates the velocity value to calculate an acceleration value.

The noise removing filter 152 is connected to the output terminal of the differentiator 150 and removes noise generated by the differentiating action of the differentiator 150.

Further, the disturbance torque calculation unit 154 is composed of an addition point, and the output from the filter 152 is + input and the output of the nominal torque calculation unit 148 is −input.

The addition result is input to the current conversion unit 156,
The disturbance torque / current is converted to the addition point 132-
Is entered.

A feature of the present invention is that the canceling unit 15 is provided between the current detecting unit 138 and the nominal torque calculating unit 148 in order to suppress current fluctuation, fluctuation, and vibration due to the influence of the current compensation system.
8 is provided.

Here, the canceling unit 158 determines the characteristic Gc of the current compensation system 146.
It has the inverse characteristic 1 / Gci of i. Therefore, the influence of the current compensation system 146 is eliminated from the current value input to the nominal torque calculation unit 148.

Further, in this embodiment, in order to avoid the generation of the impulse current, the 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 addition point 132. .

Next, the operation of the present invention will be described 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 structure is the same as that in FIG.

However, in this embodiment, since the canceling portion 158 is provided as is apparent from FIG. 1, the detected current i is multiplied by the characteristic 1 / Gci, and the current compensation is performed when the nominal torque is calculated. The influence of the characteristic Gci of the system 146 is canceled.

Therefore, according to the disturbance torque compensation system of the present embodiment, it is possible to reliably suppress the fluctuation and vibration based on the characteristic Gci of the current compensation system.

In this embodiment, the impulse current avoidance filter 160
Therefore, the target current value i ^{* in} Fig. 2 is
It is applied to the filter of 1 / (1 + τs).

 As a result, the following advantages can be obtained.

As described above, in the actual realization 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 the differential operator s in order to convert it into the torque level.

However, since the differential processing is usually noisy, a filter must be used.

Therefore, .tau..s is added in FIG. 2 and the differential processing is performed by the following equation as a whole.

Note that τ is the time constant of the filter.

As a result, in the embodiment, the armature current i and the rotational angular velocity ω are respectively expressed by the following equations.

Therefore, due to the influence of the differential term of τ · s, when a stepwise command is added to the current target value i ^* , an impulse current is required as the actual current.

This physically means that an infinite amount of current is instantaneously applied, and an extremely large load is applied to the current supply system.

Therefore, in the present embodiment, the impulse current avoidance filter 160 is installed.

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

As described above, the actual current i is not affected by the differential term τs, and the impulse current is not required as the actual current i even when the target current value i ^* step-like command is added.

Moreover, the relationship of ω-i ^* is also in an ideal state, and it has an extremely excellent load non-responsiveness.

FIG. 3 shows a block diagram of a disturbance torque compensating apparatus according to a second embodiment of the present invention. The parts corresponding to those in FIG.

A characteristic of this embodiment is that the first current detection unit 262 that detects the current value to be input to the nominal torque calculation unit 248 is not provided with the cancellation unit as in the first embodiment, but the current compensation is performed. It was installed in front of system 246.

The current compensation system 246 includes a second current detection unit 2 for current compensation.
38 are provided.

A physical system of the disturbance torque compensating device configured as described above is shown in FIG.

As is apparent from the figure, no influence of the characteristic Gci of the current compensation system is involved in the nominal torque calculation, stable current characteristics similar to those in the first embodiment are obtained, and fluctuations and vibrations of the drive unit are suppressed. Can be done.

Next, the effect of the disturbance torque compensating apparatus according to this embodiment will be described with reference to FIGS. 5 and 6.

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

Further, FIG. 6 shows an apparatus in which the current value for inputting to the nominal torque calculation unit 248 is detected before the current compensation system 246 as in the second embodiment, and the actual current i under the same conditions as in FIG. And the angular velocity ω are shown.

As is clear from FIG. 5, when the cancel unit 158 is not provided, the actual current i is affected by the current compensation system and draws a fine wave, and this tendency occurs each time the disturbance torque is compensated. Further, 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, in FIG. 6, the current i shows an increase / decrease in accordance with the disturbance torque, but does not draw a fine wave as seen in FIG. Of course, the angular velocity ω also reaches a certain line with a smooth curve, and there is little vibration or vibration thereafter.

As described above, according to the disturbance torque compensator according to the present embodiment, it is possible to stably obtain a constant drive state regardless of the application of the disturbance torque, and achieve good load non-responsiveness. it can. In particular, the device according to the present embodiment has good responsiveness and can suppress vibration and the like without time delay.

[Effects of the Invention] As described above, according to the disturbance torque compensating apparatus of the invention of claim 1 of the present application, the detected current includes the canceling unit that cancels the current compensation characteristic of the current compensation system, and Since the nominal torque is calculated from the output current value of the cancel unit, it is possible to suppress the fluctuation and vibration of the drive unit based on the characteristics of the current compensation system.

Further, according to the disturbance torque compensating apparatus according to the invention of claim 2 of the present application, the current is detected from the connection point of the drive current supply system and the current compensation system, and the nominal torque is calculated from the detected current value. Therefore, with a simple configuration, it is possible to suppress the shake and vibration of the drive unit based on the characteristics of the current compensation system without a time delay.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a disturbance torque compensating apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of a physical system of the disturbance torque compensating apparatus shown in FIG. 1, and FIG. FIG. 4 is a block diagram showing a configuration of a disturbance torque compensating device according to a second embodiment of the invention, FIG. 4 is an explanatory diagram of a physical system of the disturbance torque compensating device shown in FIG. 3, and FIG. 5 is shown in FIG. And FIG. 6 is an explanatory diagram showing the relationship between the disturbance torque, the current value, and the angular velocity when the cancel portion is not provided in the disturbance torque compensating device. FIG. 6 is the disturbance torque, current value, and angular velocity of the disturbance torque compensating device shown in FIG. FIG. 7 is an explanatory view of a general driving device, FIG. 8 is a block diagram showing a feedback compensation system of the general driving device, and FIG. 9 is the driving shown in FIG. An explanatory diagram of the main part of the physical system of the device, Fig. 10 shows an ideal disturbance torque It is an explanatory view of the compensation system. 18,118,218 ... Motor (driving part) 146,246 ... Current compensation system 148,248 ... Nominal torque calculation part 150,250 ... Differentiator (acceleration calculation part) 154,254 ... Disturbance torque calculation part 156,256 ... Disturbance torque / current conversion part 158 ... Cancel part 138,262 ... Current detection part

Claims (2)

[Claims] 1. A drive current supply system for supplying a drive current to a drive unit, a current detection unit for detecting an actual drive current supplied to the drive unit, and an actual drive current output by the current detection unit for a target current. A current compensating unit having a current compensating unit that adjusts a driving current output so as to match the current value, and a disturbance torque compensating device of a driving device for driving by inputting a predetermined driving current, And a current compensation characteristic Gci of the current compensation system added to the detected current value by the current detection section, a cancellation section for canceling by adding the characteristic 1 / Gci, and the cancellation. Estimated drive torque calculation unit that calculates the estimated drive torque from the output current value of the drive unit, Speed detection unit that detects the drive speed of the drive unit, Acceleration calculation unit that differentiates the drive speed of the drive unit and calculates the calculated acceleration When A disturbance torque calculation unit that calculates a disturbance torque from a difference value between the torque obtained from the calculated acceleration and the estimated drive torque; and a disturbance torque / current conversion unit that converts the disturbance torque amount into a current value. Disturbance torque compensator characterized by. 2. A drive current supply system for supplying a drive current to a drive unit, and a current compensation system for detecting an actual drive current supplied to the drive unit and performing feedback compensation to a target current value. In a disturbance torque compensating device for a drive device that inputs and drives a predetermined drive current, a current detection unit that detects a current from a connection point between the drive current supply system and the current compensation system, and a detected current value of the current detection unit An estimated drive torque calculation unit that calculates an estimated drive torque, a speed detection unit that detects a drive speed of the drive unit, an acceleration calculation unit that differentiates the drive speed of the drive unit, and calculates a calculated acceleration; A disturbance torque calculation unit that calculates a disturbance torque from a difference value between the torque obtained from the above and the estimated drive torque; and a disturbance torque / current conversion unit that converts the disturbance torque amount into a current value. The disturbance torque compensation apparatus according to symptoms.