JP2629682B2 - Rotation control device - Google Patents

Description

The present invention relates to a rotation control device suitable for use in, for example, a drum servo circuit of a VTR.

[Summary of the Invention]

The present invention compares a reference signal with an output signal of a pulse encoder that generates a signal having a frequency corresponding to the rotation speed of the rotating body, for example, a rotation speed detection signal of the rotating body, which is provided on the rotating body and the coaxial body, and generates a signal having a frequency corresponding to the rotating speed of the rotating body. In a system in which the rotational speed of the rotating body is controlled to a predetermined value by the comparison output, a unique variation generated in one rotation cycle of the rotating body in the output signal of the pulse encoder is stored in a memory, and thereby the rotating body is controlled. In the correction that removes the fluctuation of the output signal of the pulse encoder at the time of driving, the correction based on the information stored in the memory is not performed at the time of a transient response such as the rising of rotation, and the rising time is shortened. ,
This is to improve control performance during transient response.

[Conventional technology]

For example, in a drum speed servo circuit of a VTR,
The rotation speed of the drum motor is detected by a pulse encoder that generates a signal having a frequency proportional to the rotation speed, and the control is performed such that the frequency of the output frequency signal from the pulse encoder becomes a set reference value. The rotation speed of the camera is made almost constant.

By the way, in this case, generally, fluctuation factors such as torque ripple of the motor, eccentricity of the rotation center of the pulse encoder itself, magnetization pattern error if the pulse encoder is magnetic, and if the pulse encoder is optical, Due to the optical pattern error, the frequency detection signal from the pulse encoder includes a change in one rotation cycle of the motor. This variation is unique to each machine.

Therefore, for each machine, a specific amount of fluctuation at a plurality of appropriate positions with respect to the reference position of one rotation of the motor is stored in a memory, and the characteristic fluctuation is corrected by a signal from the memory when the motor is driven. This makes it possible to realize a servo circuit which is hardly affected by the inherent fluctuation of one rotation cycle of the motor.

Based on this idea, the fluctuation of the desired rotational speed of the motor due to the torque ripple of the motor in the steady state is stored in a memory in advance, and the torque ripple in the steady state is removed by a signal from this memory. A motor control device is known from Japanese Utility Model Laid-Open No. 58-63894.

However, when the inherent variation in the steady state is stored in the memory in advance in this way, it is not possible to cope with the variation due to differences in various conditions during actual driving of the motor. Further, it is not possible to cope with a case where the variation due to aging changes, and correction for removing the variation becomes inaccurate.

[Problems to be solved by the invention]

Therefore, the applicant has previously proposed a speed control device that learns the unique variation for each rotation and refreshes the content of the variation storage memory (Japanese Patent Application No. 61-1334685).
JP-A-62-293983, not disclosed at the time of filing the present application).

According to the preceding invention, the content of the memory for the inherent variation of one rotation cycle of the motor is the variation itself during the actual driving of the motor, and is not affected by various conditions at the time of driving and aging. It will be able to respond.

However, in the case of the above-mentioned occurrence, control at the time of transient response such as at the start of rotation of the motor becomes a problem.

That is, when the control having the learning function is performed as in the above invention, the rotation speed detection signal of the motor has a constant period in a steady state, and therefore the learning of the above fluctuation detected as an error of this period is completely performed. And the variation is well removed.

However, during a transient response such as when the motor starts up, the rotation speed is disturbed, and therefore, the period of the rotation speed detection signal greatly fluctuates. Then, this variation is handled in the same manner as the inherent variation of one rotation cycle of the drum, sequentially stored in the memory, and the correction using this is performed. At this time, the contents of the memory are obtained by adding the amount of deviation from the reference value of the rotation speed detection signal to the fluctuation of one rotation cycle (the value is originally small). When the motor starts up,
The rotation speed greatly deviates from the reference, and the motor should be supplied with a value corresponding to the large deviation and the speed should be increased quickly. Since the difference between the rotation speed detection signal and the reference value is subtracted from the difference during the current rotation, the motor supply voltage becomes low. As a result, there is a disadvantage that the rise time of the motor is delayed.

As described above, in the speed control system having the learning function for the fluctuation of one rotation cycle, the learning is erroneously performed at the time of the transient response, and the speed control is disturbed.

 The present invention has improved this point.

[Means for solving the problem]

The rotation control device according to the present invention is a rotation control device having a servo loop for controlling the rotation speed of the rotating body to be substantially constant, wherein the rotation control device includes: a rotation speed detection unit configured to detect the rotation speed of the rotating body; Speed error data forming means for outputting rotation speed error data based on the rotation speed detection signal from the speed detecting means; and differentiating the output signal from the speed error data forming means to obtain a variation in the rotation speed of the rotating body. And a memory means for learning and storing a unique variation of one rotation cycle of the rotating body from the variation of the rotating speed of the rotating body, and obtaining the difference from the variation of the rotating speed at the time of driving the rotating body. A comb filter means for removing a variation inherent in the one rotation cycle, and one rotation cycle of the rotating body from the comb filter means for controlling rotation of the rotating body. An adder for adding a variation of the rotation speed of the rotating body from which the inherent variation has been removed and a rotation speed detection signal from the rotation speed detector, and when the rotation speed error data is equal to or higher than a predetermined level, By resetting the memory means of the comb filter, the operation of learning and storing the unique variation of one rotation cycle of the rotating body is stopped, and the unique variation of the one rotation cycle is removed. Correction is not performed substantially.

[Action]

At the time of a transient response, it works in the same manner as a speed control system having no function of removing the fluctuation of one rotation cycle. Therefore, the characteristics at the time of transient response such as when the motor starts up are not deteriorated as compared with the conventional one. In addition, in the steady state, the fluctuation in one rotation cycle is learned and written into the memory every rotation, and the correction of the fluctuation removal by the signal read from the memory is performed, so that the control performance is improved.

〔Example〕

FIG. 1 shows an example in which the present invention is applied to a drum servo circuit of a VTR, which has not only a speed servo system but also a phase servo system.

In the figure, reference numeral (1) denotes a drum motor which rotates at, for example, 30 rps in a steady state. (2) is a rotation detector having a rotating body which rotates with the rotation of the drum motor (1). The rotation detector (3) (including the waveform shaping amplifier) controls the rotation speed of the drum motor (1). A corresponding frequency signal FG is obtained. From the detection head (4) (including the waveform shaping amplifier), one signal per rotation of the motor (1) is obtained.
A signal PG indicating the rotation phase of the motor is obtained.

As shown in FIG. 2A, the frequency signal FG has a constant duty factor per one rotation of the motor (1).
For example, six periods of a 50% rectangular wave are obtained.

At this time, based on the position of the pulse PG from the detection head (4), the position of each one of the six periods of the signal FG is uniquely determined.

This frequency signal FG is supplied to a speed error data forming circuit (5). In this example, speed error data is obtained as count value data from this forming circuit (5). That is, the formation circuit (5) has a counter, the counter is reset at the rising edge of the frequency signal FG (FIG. 2A), the count value of the counter is latched at the falling edge of the frequency signal FG, and the count value is converted into an error. Output as data. If the count value of the counter is expressed in analog form, it will be as shown in FIG. 2B. At each position P ₁ , P ₂ , ΔP _{6 based on} the position of the pulse PG, every one rotation of the motor,
Data N ₁ , N ₂ , ‥‥ N ₆ for each one cycle of the signal FG sequentially
Will be obtained repeatedly. This data N ₁ , N ₂ , ‥‥
Generating position P ₁ to P of the N _{6 6} is a position stated on the basis of the occurrence position of the pulse PG for one rotation of the rotation detector (2).

The angular velocity error data SD from this forming circuit (5) is
The change (angular acceleration) is supplied to the differentiating circuit (6).
Is converted to data. The angular acceleration data is supplied to a multiplication circuit (7), multiplied by a constant K ₀ (K ₀ <1), and then supplied to a digital comb filter circuit (8), where one rotation cycle of the motor (1) is performed. Is corrected to remove the inherent variation of

FIG. 3 shows an example of the digital comb filter (8). Reference numeral (81) denotes its input terminal. The angular acceleration data αD from the multiplication circuit (7) through this input terminal (81) is subtracted by a subtraction circuit (82). The angular acceleration data αDCT from which the variation has been removed is obtained at the output terminal (83) from the data αD, as will be described later. To be able to

In this case, the variation of one rotation cycle of the motor (1) is obtained for each of the acceleration data at each position P ₁ , P ₂ , ΔP ₆ ,
By subtracting each of them from the input acceleration data αD, a correction operation of fluctuation removal is performed, and (84 ₁ ) to (8)
4 ₆₎ is a digital feedback type comb filter to obtain a variation in the position P ₁ to P _6, respectively. And these comb filters (84 ₁₎ to (84 ₆₎ is provided on the input side and the output side, the switch circuits SW ₁ and SW ₂ that is switched in conjunction, in synchronization with the input acceleration data αD It is switched and inserted between the input terminal (81) and the subtraction circuit (82).

That, is supplied to the pulse PG is a timing signal formation circuit from the signal FG and the detection head of the detection head (3) (4) (20), which from the switch circuits SW ₁ and SW ₂
Is obtained, whereby the switching circuits SW ₁ and S
Period input acceleration data is obtained each data N ₁ to N ₆ of W ₂ each position P ₁ to P ₆ of a terminal (81), that the signal FG
Are sequentially switched to the terminals a to f at intervals of one cycle.

Therefore, the filter (84 ₁ ) through the switch path SW ₁
Angular acceleration data of the position P ₁ to the filter (84 ₂₎ The angular acceleration data position P ₂ is the ‥‥ filter (84 ₆₎ is supplied with the angular acceleration data of the position P _6, it is processed , it will be sequentially taken out from the switch circuit SW _2.

In this case, digital feedback type comb filter (84 ₁ )
Since the structure of - (84 ₆₎ it is exactly the same configuration, in the third illustrated example for its specific configuration, shown for only the filter (84 ₁₎ for data at the position P _1, describes this, Others are omitted.

The data input to the digital filter (84 ₁ ) is passed through a subtraction circuit (85) and an acceleration circuit (86) to a limiter (87).
After being fed is level limited to, is supplied to a delay circuit composed of the memory element (88), the speed data in one revolution in one rotation cycle (this example of the motor is 6 samples of N ₁ to N ₆ This is delayed by six samples). That is, the delay circuit (88), every time the data of the filter (84 ₁₎ at the position P ₁ arrives, the stored contents are updated. The output of the delay circuit (88) is supplied to the multiplication circuit (89) K ₄
(K ₄ <1). The output of the multiplication circuit (89) is fed back to the subtraction circuit (85) and is subtracted from the input acceleration data. The output signal of the delay circuit (88) is added to the addition circuit (86).
And is added to the subtraction output from the subtraction circuit (85).

With the above configuration, the average value of the input acceleration data is obtained at the output of the delay circuit (88), and this is output from the filter (84 ₁ ) via the multiplication circuit (89).

Therefore, the output data obtained from each of the filters (84 ₁ ) to (84 ₆ ) corresponds to each of the positions P ₁ , P ₂ ,
In ‥‥ P _6, a represents the shift amount from the center value. Moreover, since this is the acceleration data at each of the rotational angle positions P _{1 to} P _6, that is, the integral value of the speed fluctuation component, it is a unique variation of one rotation cycle of the motor at each of the positions P _{1 to} P ₆ .

That is, the addition circuit (86), the limiter (87), and the delay circuit (88) constitute an integration circuit, thereby learning the steady variation and the inherent fluctuation of one rotation cycle of the motor while learning.
This variation is obtained from the delay circuit (88), that is, the memory.

Thus, variation in the respective positions P ₁ to P ₆ obtained is supplied to a subtracting circuit (82), it is subtracted from the input data .alpha.D. Therefore, the output end (83) of the comb filter (8)
Provides a speed error from which the inherent variation of one rotation cycle of the motor has been removed.

The output of the comb filter (8) is supplied to an adding circuit (9).

The data obtained from the comb filter (8) is only the AC component of the speed error. Then, the speed error data from the formation circuit (5) is supplied to the multiplication circuit (10), and is multiplied by a constant K ₁ (K ₁ <1).
It is supplied to the addition circuit (9) via 1). in this case,
The limiter (11) limits the input to below the limiter level when its input is higher than the limiter level. At the time of a transient response at the time of rising of the rotation of the motor (1), the input of the limiter (11) becomes larger than the limiter level. When the limiter operation is performed as described above, the memory reset signal RS is output from the limiter (11).
Is obtained, and the memory reset signal RS is applied to each of the delay circuits (8 ₁ ) to (84 ₆ ) of the comb filter (8).
The data is supplied to the memory composing 8), the memory is reset, and its contents are made zero. Therefore, the integration operation, that is, the learning operation is stopped, and each filter (84 ₁ ) to
The output of (84 ₆₎ is zero.

As a result, a state is reached in which the operation of removing the fluctuation of one rotation cycle of the motor is not performed. Therefore, at the time of a transient response at the start of the motor, the operation is the same as that of the conventional apparatus without the fluctuation removing function, and the start time is not slower than that of the conventional apparatus.

Next, the phase servo system will be described. A pulse PG (FIG. 2C) from the detection head (4) is supplied to a phase error forming circuit (21). A signal VREF (FIG. 2D) having a vertical cycle of the video signal is supplied to the phase error forming circuit (21) as a phase reference signal. The forming circuit (21) forms a signal corresponding to the phase difference between the two signals. For example,
As shown in FIG. 2E, the counter is reset by the pulse PG, counting is started from this point, the count value of the counter is latched by the vertical cycle signal VREF, and the latched count value is used as the phase error data. Is output.

This phase error data is supplied to a multiplication circuit (22), multiplied by a constant K ₂ (K ₂ <1), and then supplied to an addition circuit (9) via a limiter (23), and to an integration circuit ( The integrated output is supplied to the multiplication circuit (25), multiplied by a constant K ₃ (K ₃ <1), and then supplied to the addition circuit (9).

The output of the adder circuit (9) is a D / A converter (2
6) is converted into an analog voltage, which is supplied to the drum motor (1) via the drive amplifier (27), so that the drum motor (1) is phase-synchronized with a signal having a constant speed and a vertical cycle. And rotate.

It should be noted that the phase servo error causes disturbance to the speed servo system at the time of transient response such as when the motor starts up. Therefore, in this example, the phase servo error is reset to zero during the transient response.

That is, the multiplication circuits (22) and (24) have memories for holding the output data, but the limiters (11)
In, when there is the limiter level greater than the input, the reset with the memory of the aforementioned filter (84 ₁₎ to (84 _6), by a memory reset signal RS also memory of these multiplier circuits (22) and (24) This is to reset the stored contents to zero.

In the above example, since the data is digital data, a digital filter is used for the filter (8). However, an analog filter using an analog memory such as a CCD is used for the delay circuit (88), and the speed error, The phase error may be handled as an analog voltage.

Also, the present invention is not limited to the drum servo circuit of the VTR,
It can be applied to all cases of the rotation speed servo circuit of the rotating body.

The above operation can be controlled using a microcomputer.

〔The invention's effect〕

In the present invention, detection is performed while learning a variation inherent in one rotation cycle of the rotating body and removing it from the speed error. In a transient response such as when the rotation of the rotating body rises, learning is stopped and the speed error is reduced. In the transient response, the characteristic is similar to that of the conventional speed servo system that does not remove and correct the inherent fluctuations. Is prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a timing chart for explaining the embodiment, and FIG. 3 is a block diagram of an embodiment of a main part thereof. (1) is a drum motor, (2) is a rotation detector, (3)
(4) is a rotation detecting head, (5) is a speed error forming circuit, (8) is a comb filter for removing a variation inherent in one rotation cycle of the motor (1), and (11) is a transient response. A limiter (88) is a delay circuit composed of a memory.

Claims (1)

(57) [Claims] 1. A rotation control device having a servo loop for controlling the rotation speed of a rotating body to be substantially constant, the rotation control device comprising: a rotation speed detecting means for detecting a rotation speed of the rotating body; Speed error data forming means for outputting rotation speed error data based on a rotation speed detection signal from the speed detecting means; and differentiating the output signal from the speed error data forming means to obtain a variation in the rotation speed of the rotating body. And a memory means for learning and storing a unique variation of one rotation cycle of the rotating body from the variation of the rotating speed of the rotating body, and obtaining the difference from the variation of the rotating speed when the rotating body is driven. A comb filter means for removing an inherent variation of the one rotation cycle; and one rotation of the rotating body from the comb filter means for controlling rotation of the rotating body. And an adding unit for adding a rotation speed detection signal from the rotation speed detection unit, the rotation speed error data being equal to or greater than a predetermined level. when,
By resetting the memory means of the comb filter, the operation of learning and storing the unique variation of one rotation cycle of the rotating body is stopped, and the correction for removing the unique variation of the one rotation cycle is performed. A rotation control device, which prevents substantially from occurring.