JP3086503B2 - Feedback comb filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feedback comb filter, and more particularly to a feedback comb filter using software included in a software servo system used for a servo system of a micro motor such as a drum motor of an 8 mm VTR integrated with a camera. Regarding filters.

[0002]

2. Description of the Related Art A technical report of the Institute of Television Engineers of Japan, Vol. 12, No. 17, pp37-4
The feedback comb filter in the conventional software servo system described in "Development of Software Servo System in VTR" published in No. 2 was processed as shown in FIGS. That is, if the number of samplings per rotation of the drum motor is six, after starting the comb filter processing, first, each area R0 to R5 of the RAM is read.
The speed error control data stored in the accumulator A
And using the area R6 of the RAM. Then, the final data after the shift is stored in the areas R0 and R7 of the RAM.

Next, the result of multiplying the data in the area R7 of the RAM by the notch depth K (here, K = 1/32) is expressed as R
The data is written in the area R8 of the AM, and if the data in the area R8 is negative, the data is converted to positive data by ORing "11111000". RA thus obtained
By subtracting the speed error control data in the area R8 of M from the speed error data in the speed error storage RAM (DSP), the simple speed error data becomes speed error control data having a notch characteristic. Then, the bias value is further subtracted to make the speed error control data only the DC component, and the speed error control data in the area R0 of the RAM is added, so that the speed error control data for removing the FG unevenness is obtained. can get.

[0004]

When a drum servo system for an ultra-small motor such as an 8 mm VTR is constructed, it is necessary to increase the gain of the servo system and reduce quantization errors. The number of samplings in rotation needs to be increased. However, when a feedback type comb filter based on the conventional serial processing is used, the number of shifts of the speed error control data becomes very large. The speed error control data is error data of a servo system, and a microcomputer used for a feedback comb filter generally has a 16-bit or 24-bit configuration, so that the time required for data shift is considerably long.
In the examples shown in FIGS. 4 and 5, the number of samplings in one rotation is six, but in general, the number of samplings is set to 12 or more in many cases. Therefore,
As can be seen from FIG. 4, even if the number of samplings is six, the processing required for data shift is quite large, and if sampling is performed twelve times, more processing is required.
In this case, if an 8-bit microcomputer capable of 16-bit operation is used, the processing time of the feedback comb filter becomes 50% or more of the processing time of the entire drum servo system, which is a great hindrance to increasing the sampling frequency.

Therefore, a main object of the present invention is to provide a feedback comb filter capable of increasing a sampling frequency.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a feedback comb filter using software for removing FG unevenness in a servo system of a motor which generates N speed error control data per rotation in response to an FG signal. Label discriminating means for discriminating N labels that change cyclically in response to the FG signal, N control data storing means for selecting one of them according to the discrimination result of the label discriminating means, The notch data obtained by multiplying the control data stored in the control data storage means selected according to the determination result of the label determination means by the notch depth K is subtracted from the latest speed error control data to obtain a feedback type comb. An output unit that outputs the output data of the filter; A feedback control unit for adding the control data stored in the data storage unit and storing the control data as control data in the control data storage unit selected according to the previous determination result of the label determination unit; It is a comb filter.

[0007]

The speed error control data obtained by detecting the speed error for each sampling is stored in the corresponding speed error control data storage means, for example, in a predetermined area of the RAM. For example, the label formed in another area of the RAM is changed (incremented) in response to the FG signal from the motor, and the label determination means determines what numerical value the label has. Then, processing for generating speed error control data for removing FG unevenness is performed according to the label. As a result, the speed error control data can be efficiently processed, and the same characteristics as those of the conventional feedback type comb filter by serial processing can be obtained without data shifting.

[0008]

According to the present invention, since there is no need for data shift, the time required for the data shift can be remarkably shortened as compared with the conventional feedback type comb filter by serial processing, so that the sampling frequency can be increased. The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0009]

Referring to FIG. 3, a feedback comb filter 10 of this embodiment is included in a servo microcomputer 14 for a drum motor 12. In the servo microcomputer 14,
The PG signal and F output from the drum motor 12 and amplified by the PG amplifier 16 and the FG amplifier 18, respectively.
The G signal is input. The PG signal is output from the phase error detector 20.
And compared with the reference phase. As a result, the phase error data is output from the phase error detection unit 20. On the other hand, the FG signal is input to the speed error detector 22, where speed error data is generated. This speed error data is processed in the feedback comb filter 10 and output as speed error control data for removing FG unevenness of the drum motor 12. Then, the speed error control data output from the feedback comb filter 10 and the phase error data output from the phase error detection unit 20 are synthesized by the synthesis unit 24. The data synthesized by the synthesizing unit 24 is converted into an analog control signal by a D / A conversion unit 28 via a low-pass filter 26 and output to a driver 30. The driver 30 controls the drum motor 12 in response to the control signal output from the servo microcomputer 14.

Next, the processing of the feedback comb filter 10 will be described with reference to the flow charts shown in FIGS.
The flow charts shown in FIG. 1 and FIG.
9 shows feedback comb filter processing when the number of rotations is six. When the comb filter processing is started, steps S1, S3, S5, S7 and S
9, the label values stored in the area R10 of the RAM (not shown) are "0", "1", "2", "3",
It is determined which of “4” and “5”. The label stored in this area R10 is the servo microcomputer 1
The value is incremented for each FG signal input to 4, and is returned to "0" when the value exceeds "5". The label may be formed in the RAM or may be created by another counter.

The speed error control data sequentially input from the speed error detector 22 to the feedback comb filter 10 is RA
M are stored in six areas R0 to R5. And R
According to the label value stored in the area R10 of the AM, the speed error control data corresponding to the label value out of the speed error control data stored in each of the areas R0 to R5 of the RAM is the same as the data processing in the prior art described above. Similarly, data processing is performed to generate speed error control data for removing FG unevenness. Since the details of this data processing have been described above, duplicate description will be omitted here.

As described above, since the speed error control data is processed according to the label which changes according to the FG signal, there is no need to shift the data as in the related art, and therefore, the processing time of the feedback comb filter is reduced. It becomes smaller with respect to the processing time of the entire servo system, and the sampling frequency can be increased. This is a great advantage particularly in a servo system of a micro motor such as a drum motor of 8 mm VTR.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a part of a process according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a part of a process according to one embodiment of the present invention;

FIG. 3 is a block diagram showing a servo system including a feedback comb filter according to one embodiment of the present invention.

FIG. 4 is a flowchart showing a part of the processing of the conventional feedback comb filter.

FIG. 5 is a flowchart showing a part of the processing of the conventional feedback comb filter.

[Explanation of symbols]

 10 Feedback comb filter 12 Drum motor 14 Servo microcomputer 22 Speed error detector

Claims (1)

(57) [Claims] 1. A feedback comb filter by software for removing FG unevenness in a servo system of a motor that generates N speed error control data per rotation in response to an FG signal. Label discriminating means for discriminating N labels that change cyclically, N control data storing means of which one is selected according to the discrimination result of the label discriminating means, and according to the discrimination result of the label discriminating means An output for subtracting notch data obtained by multiplying the selected control data stored in the control data storage means by the notch depth K from the latest speed error control data and outputting it as output data of the feedback comb filter. Means, stored in the control data storage means selected according to the determination result of the label determination means in the DC component of the output data. A feedback comb filter, further comprising storage control means for adding the control data to the control data storage means and storing the control data in a control data storage means selected according to the previous determination result of the label determination means.