JPS63129877A - Rotation controller - Google Patents

Abstract

PURPOSE:To prevent the deterioration in characteristics upon transient response, by a method wherein learning is stopped upon the transient response, such as the rise-up of the rotation of a rotating body or the like, and correction for removing it from the error of a speed is prevented. CONSTITUTION:The drum servo circuit of a VTR detects the rotation of a drum motor 1 by detectors 2-4 and controls the driving of the motor 1 by the value of detection through a D/A converter 26 and a drive amplifier 27. The frequency signal FG from the detectors 2-4 is supplied to the forming circuit 5 of the error of speed and is inputted into an adding circuit 9 through a differentiating circuit 6, a multiplying circuit 7, a digital comb type filter circuit 8, the multiplying circuit 10 and a limiter 11 and a correction to remove the amount of proper fluctuation per one rotating period of the motor 1 is effected. On the other hand, a pulse PG is supplied to a phase error forming circuit 21 and the data thereof is inputted into said adding circuit 9 through the multiplying circuit 22, the limiter 23, an integrating circuit 24 and the multiplying circuit 25 respectively. Thus, the drum motor 1 may be rotated with a constant speed and a synchronized phase.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] 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]

This invention compares a rotational speed detection signal of a rotating body, for example, an output signal of a pulse encoder provided on a rotating body and a coaxial body and generates a signal with a frequency corresponding to the rotational speed of the rotating body, with a reference. In devices that control the rotational speed of a rotating body to a predetermined value using a comparative output, the unique variation that occurs in one rotation period of the rotating body is stored in a memory among the output signals of the pulse encoder. This is a device that performs correction to remove fluctuations in the output signal of the pulse encoder during driving, but does not perform correction using information stored in memory during transient responses such as at the rise of rotation, so it can speed up the rise time, etc. , which aims to improve control performance during transient response.

[Conventional technology]

For example, in the drum speed servo circuit of a VTR,
The drum monitor detects the rotational speed of the drum motor with a pulse encoder that generates a signal with a frequency proportional to the rotational speed, and controls the output frequency signal from this pulse encoder so that the frequency of the output frequency signal becomes a set reference value. The rotation speed of is kept approximately constant.

By the way, in this case, there are generally fluctuation factors such as motor torque ripple, eccentricity of the rotation center of the pulse encoder itself, magnetization pattern error if the pulse encoder is magnetic, and error in the magnetization pattern if it is optical. Due to the optical pattern error, the frequency detection signal from the pulse encoder includes fluctuations in one rotation period of the motor.

This variation is unique to each aircraft.

Therefore, for each machine, the unique fluctuation amount at multiple appropriate positions with respect to the reference position of one rotation of the motor is stored in memory, and when the motor is driven, the unique fluctuation amount is corrected using the signal from this memory. By doing so, it is possible to realize a servo circuit that is hardly affected by the inherent fluctuations in one rotation period of the motor.

Based on this idea, the variation due to torque ripple of the motor in a steady state of the desired rotational speed of the motor is stored in advance in memory, 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 Application Publication No. 58-63894.

However, when the unique variation in the steady state is stored in the memory in advance in this way, it is not possible to deal with changes in the variation due to differences in various conditions during actual motor driving. Furthermore, it is not possible to cope with the case where the above-mentioned variation due to aging changes, and the correction for removing the above-mentioned variation becomes inaccurate.

Therefore, the applicant previously proposed a speed control device that learns the unique variation for each rotation and refreshes the memory contents for storing the variation (Patent Application No. 61-134).
685).

According to the present invention, the contents of the memory for the inherent fluctuations in one rotation period of the motor are the actual fluctuations during driving of the motor, and are independent of differences in various conditions during driving and changes over time. It will be possible to respond.

[Problem that the invention seeks to solve]

However, in the case of the above invention, control at the time of a transient response such as when the rotation of the motor starts up becomes a problem.

In other words, when performing control with a learning function as in the previous invention, the motor rotational speed detection signal has a constant cycle in a steady state, so the learning of the above fluctuation detected as an error in this cycle is completely ignored. The variation is successfully removed.

However, during a transient response such as when the motor starts up, the rotational speed is disturbed, and therefore the period of the rotational speed detection signal fluctuates greatly. Then, this variation is handled in the same manner as the inherent variation of one rotation period of the drum, and is sequentially stored in the memory, and correction is performed using this variation. The contents of the memory at this time are the variation of one rotation period (which is originally small) plus the deviation of the rotational speed detection signal from the reference value. When the motor starts up, the rotational speed deviates significantly from the standard, and the motor should be supplied with a value corresponding to this large deviation to quickly increase the speed, but when correction is made using the signal from the memory mentioned above, Since the deviation from the reference value of the rotational speed detection signal in the previous rotation is offset by the deviation in the current rotation, the motor supply voltage becomes lower. As a result, the start-up time of the motor is slow.

As described above, in a speed control system having a learning function for a variation in one rotation period, during a transient response, learning is executed incorrectly, resulting in disturbance of speed control.

This invention improves this point.

[Means for solving problems]

In the present invention, in a rotation control device that learns the variation of one rotation period of a rotating body and stores it in a memory, and performs correction to remove the variation using a signal read from this memory, during a transient response, this A means is provided to prevent correction from being performed.

[Effect]

During a transient response, similar to a speed control system that does not have the function of removing fluctuations in one rotation period, (ffij<. Therefore,
Characteristics during transient response such as when the motor starts up do not deteriorate compared to conventional ones. Furthermore, in a steady state, the fluctuations in one rotation period are learned every revolution and written into the memory, and the fluctuation removal is corrected by the signal read from the memory, 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, (11 is a drum motor, which rotates at, for example, 30 rps in a steady state. (2) is a rotation detector having a rotating body that rotates with the rotation of this drum motor (1). A frequency signal FG corresponding to the rotation speed of the drum motor (11) is obtained from the detection head (3) (including the waveform shaping amplifier), and a frequency signal FG corresponding to the rotation speed of the drum motor (11) is obtained from the detection head (4) (including the waveform shaping amplifier). 1 per rotation
A signal PC indicating the rotational phase of the motor is obtained.

This frequency signal FG has a constant duty factor per rotation of the motor (1) as shown in Fig. 2A.
For example, six periods of a 50% square wave are obtained.

At this time, if the position of the pulse PC from the detection head (4) is used as a reference, the position of each of the six periods of this signal FC is determined in a single manner.

This frequency signal FC is applied to the 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 forming circuit (5) operates a counter, and the counter is reset at the rising edge of the frequency signal FG (A in Fig. 2), and the count value of the counter is latched at the falling edge of the frequency signal FC, and the count value is set as an error. Output as data. If the count value of the counter is expressed in an analog way, it will be as shown in FIG. 2B, and each position P1 . P2. . . . At P6, data N1 . N2. ...NG will be obtained repeatedly.This data Ni I N2 + ...
...N8 generation positions P1 to P6 are rotation detector (2) 1
Regarding rotation, this is a fixed position based on the generation position of the pulse PC.

The angular velocity error data SD from this forming circuit (5) is
It is supplied to the differentiation circuit (6) and its change (angular acceleration)
is converted into data. This angular acceleration data is supplied to a multiplication circuit (7), multiplied by a constant Ko (Ko<1), and then supplied to a digital comb filter circuit (8) to calculate the characteristic of one rotation period of the motor (1). A correction is made to remove the variation.

Figure 3 is an example of this digital comb filter (8).
(81) is its input terminal, and the angular acceleration data αD from the multiplication circuit (7) through this input terminal (81) is input to the subtraction circuit (
82), the variation of one rotation period of the motor (1) is removed from this data αD as will be described later, and the angular acceleration data αDCT from which the variation has been removed is supplied to the output terminal (83). will be obtained.

In this case, the variation in one rotation period of the motor (1) can be obtained by subtracting each of the acceleration data at each position P1+P2+...P6, and by subtracting each of them from the input acceleration data αD, the variation can be removed. They perform a correction operation, and (841) to (84G) are digital feedback comb filters for obtaining fluctuations at positions P1 to P6, respectively. And these (square filter (841)
~(84G) are switch circuits SWx and SW2 provided on the input side and output side of these and switched in conjunction with each other.
Therefore, it is switched in synchronization with the input acceleration data αD and is selectively inserted between the input terminal (81) and the subtraction circuit (82).

That is, the signal FC from the detection head (3) and the pulse PC from the detection head (4) are supplied to the timing signal forming circuit (20), which then outputs the switch circuit SW.
and SW2 switching signals are obtained, whereby the switch circuits SW1 and SW2 operate during the period during which human acceleration data N1 to N6 of each position P1 to P6 from the terminal (81) are obtained, that is, the signal The terminals a y f are sequentially switched for each period of one FC cycle.

Therefore, through the switch circuit SW1, the angular acceleration data of position 1pt is sent to the filter (84□), and the angular acceleration data of position P2 is sent to the filter (842)...
Angular acceleration data at position P6 is supplied to the filter (84s), processed, and sequentially taken out from switch circuit SW2.

In this case, a digital feedback comb filter (841)
~(846) are exactly the same configuration, so the specific configuration example in FIG.
Only the filter (84s) for the data in is shown and explained, and the others are omitted.

The data input to the digital filter (841) passes through the subtraction circuit (85) and addition circuit (86) to the limiter (
87) and is level-limited, then supplied to a delay circuit (88) consisting of a memory element, and is supplied to a delay circuit (88) consisting of a memory element, where the speed data corresponds to 6 times (N1 to N6) in one rotation period of the motor (in this example, one rotation).
Since it is a sample, it is delayed by 6 samples). In other words, the delay circuit (88)
), the stored contents are updated every time data at position P□ arrives. The output of this delay circuit (88) is supplied to a multiplication circuit (89) and multiplied by 4 (N4<1).

The output of this multiplication circuit (89) is fed back to the subtraction circuit (85) and subtracted from the input acceleration data. Further, the output signal of the delay circuit (88) is fed back to the adder circuit (86) and added to the subtracted output from the subtracter circuit (85).

With the above configuration, the average value of the input acceleration data is obtained as the output of the delay circuit (88), and this is the average value of the input acceleration data.
It is outputted from the filter (841) through the filter (841).

Therefore, the output data obtained from each filter (841) to (846) is
1. P2. ... represents the deviation from the center value at P6. Furthermore, since this is acceleration data at each rotational angular position P1 to P6, that is, an integral value of a speed fluctuation component, it is a unique variation of one rotation period of the motor at each position P1 to P6.

That is, the adder circuit (86), the limiter (87), and the delay circuit (88) constitute an integrator circuit, which constantly learns the unique variation of one rotation period of the motor, and the delay circuit (88). ) In other words, this variation is obtained from memory.

The fluctuations at each of the positions P1 to P[, obtained in this way, are supplied to the subtraction circuit (82) and subtracted from the input data αD. Therefore, at the output end (83) of the rhombic filter (8), a speed error is obtained in which the inherent variation of one rotation period of the motor is removed.

The output of the comb filter (8) is fed to an adder circuit (9).

The data obtained from the comb filter (8) is only the alternating current component of the skin error. Therefore, the formation circuit (5
) is supplied to a multiplier circuit (10), multiplied by a constant by 1 (K < 1), and then supplied to an adder circuit (9) via a limiter (11). In this case, the limiter (11) limits the input to below the limiter level when the input is greater than the limiter level. During a transient response at the start of rotation of the motor (11), the input of this limiter (11) becomes greater than the limiter level.And when the limiter operation is performed in this way, the memory reset signal is output from this limiter (11). R3 is obtained, and this memory reset signal R3 is applied to each filter (841) to (846) of the comb filter (8).
) is supplied to the memory constituting each delay circuit (88) to reset the memory and zero its contents. Therefore, the integration operation, that is, the learning operation, is stopped, and the output of each filter (841) to (84g) is set to zero.

As a result, a state is reached in which the operation to remove the fluctuation of one rotation period of the motor is not performed. Therefore, the transient response when the motor starts up is the same as that of the conventional mounting without the above-mentioned fluctuation removal function, and the start-up time is not slower than that of the conventional one.

Next, to explain the phase servo system, the detection head (4
) (FIG. 2C) is supplied to a phase error forming circuit (21). Further, a signal VRIEF (FIG. 2D) of the vertical period of the video signal is supplied to the phase error forming circuit (21) as a phase reference signal. This forming circuit (21) forms a signal according to the phase difference between the two signals. For example, as shown in Fig. 2E, the counter is reset by the pulse PC, and counting starts from this point.The counter value at that time is launched by the vertical period signal VRIEF, and the launched count value is shifted to the phase. This is output as error data.

This phase error data is supplied to a multiplier circuit (22), multiplied by a constant by 2 (K2<1), and then a limiter (22)
3) to the adder circuit (9), and also to the integrator circuit (24) for integration, and the integrated output is supplied to the multiplier circuit (25) to multiply the constant by 3 (K3<1). After that, it is supplied to the adder circuit (9).

Then, the output of the adder circuit (9) is the output of the D/A converter (2).
6) is converted into an analog voltage, and this is supplied to the drum motor (1) via the drive amplifier (27), so that the drum motor (1) has a constant speed and
It rotates in phase synchronization with the vertical period signal.

Note that the phase servo error occurs every time a disturbance is caused to the speed servo system during a transient response such as when the motor starts up. Therefore, in this example, the phase servo error is reset to zero during this transient response.

That is, the multiplier circuits (22) and (24) have memory for holding output data, but the limiter (
11), when there is an input greater than the limiter level, the memories of the aforementioned filters (84t) to (846) are reset and the multiplier circuits (22)
The memories (24) and (24) are also reset by the memory reset signal R3, and their stored contents are set to zero.

In addition, in the above example, since the data is digital data, a digital filter was used as the filter (8).
An analog filter using an analog memory such as a CCD may be used for the delay circuit (88), and speed errors and phase errors may be treated as analog voltages.

Furthermore, this invention is not limited to VTR drum servo circuits.
It can be used in all cases of rotation speed servo circuits for rotating bodies.

Note that the above operations can be controlled using a microcomputer.

〔Effect of the invention〕

In this invention, the unique variation of one rotation period of the rotating body is detected while learning and removed from the speed error, and the learning is stopped at the time of a transient response such as when the rotation of the rotating body starts, and the speed error is eliminated. Since no correction is made to remove the inherent fluctuations during transient response, it is similar to a conventional speed servo system that does not remove or correct inherent fluctuations, and this reduces the possibility of deterioration of characteristics during transient response, such as rapid rise. is to be prevented.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] The rotational speed of the rotating body is controlled to be substantially constant based on a detection signal of the rotational speed of the rotating body, and the device learns a variation inherent in one rotation period of the rotating body in the rotational speed detection signal. The stored variation is used to perform a correction to remove the variation in the rotational speed detection signal when the rotating body is driven, and also to remove the variation during a transient response of the rotation of the rotating body. A rotation control device in which correction is substantially not performed.