JPS5983066A - Apparatus for analysis of frequency - Google Patents

Abstract

PURPOSE:To enable the arbitrary setting of frequency resolving capacity, by providing a trigonometric function generator for inputting a reference signal, a multiplier for inputting vibration data and the output of the function generator and a subtracter, an integrator and an operator succeeding to the former two. CONSTITUTION:A reference signal P is inputted to a trigonometric function generator 14 while vibration data Xi and the output of the function generator 14 are inputted to a multiplier 10a and the data xi and the output of the function generator 14 are inputted to a multiplier 10b. The outputs of division devices 13a, 13b are respectively inputted to an amplitude operator 15 and an output operator 16. A subtracter 11a inputs the outputs of the divider 13a and the multiplier 10a and the output thereof is inputted to an integrator 12a. It is similar with respect to a subtracter 11b. By this method, a frequency analysis apparatus capable of arbitrarily setting frequency resolving capacity can be obtained.

Description

[Detailed description of the invention] The present invention relates to a frequency analyzer.

In the conventional frequency analyzer, as shown in the block diagram of FIG. 1, vibration signals a. It is input to the fA/D converter 02, sampled at fixed time intervals Δt, converted into digital quantities, and then stored in the time series data memory 03. When the zumbling amount reaches a fixed number N, it is processed by software or hard logic. The fast Fourier transformer 04 performs gold Fourier transform on the time series data, and the spectrum data bl
obtain. After the spectrum data is temporarily stored in the spectrum data memory 05, it is transferred to an output device such as a plotter.
o Output to 6 ○ The method for converting time series data into full spectrum data using the fast Fourier conversion algorithm is as follows.

Data
The finite discretized Fourier transform X of is expressed by the equation (1). Here, the Fourier spectrum X is a complex number, and its real part X11 and imaginary part XI are expressed by the equation (2).

Here, the relationship between the analysis frequency f and the sampling frequency f8 is expressed by equation (3).

However, such a device has the following drawbacks.

(11 In the case of continuous data, the data interval 'l
: ￥r It is necessary to divide the data by a fixed number of data, and if we focus on an arbitrary frequency ρ, there is only one C'i in one data interval.
I can't get any results.

(2) Cuff power If for frequency ρ is the number of data) I and sampling frequency f! It is determined by

The present invention was proposed in response to this situation, and proposes a frequency analysis device using Fourier transform of continuous data that can arbitrarily set the r'tota angle capability.
For the purpose of
and the output of the trigonometric function generator 14, and the reducing η tree 11a that inputs the output of the same power T generator 10a and the output of the divider 1) l3a, which will be described later. It consists of an integrator 12a that inputs the output of the subtracter 11a, and a divider 13a that inputs the output of the integrator 12FL,
The other series is constructed in the same manner as the one series, and the outputs of the 2 division 7r units 13a and 13b are respectively ? 1 swing rlJ
The fjc characteristic is that the input is input to the arithmetic unit 15 and the phase arithmetic unit 16. An embodiment of the present invention will be explained with reference to the drawings. Fig. 2 is a block diagram thereof, and Fig. 3 is a block diagram of the present invention. FIG. 2 is a block diagram showing an embodiment in which the method is applied to a control system for a hull vibration damper.

First, in FIG. 2, P is a reference signal input to the trigonometric function generator 14, 109 is a multiplier, and vibration data, γ
l and the signal of the trigonometric function generator 14 are input. II
a is a subtracter, and the output of the multiplier JOB and the divider 1 to be described later
The output of 3a and the gold input are input. 12a is an integrator which inputs the output of the subtracter 11a. 13ft is a divider, which inputs all the outputs of the integrator 12a, and receives the output t of the divider 13&
010b is a multiplier that is divided into the amplitude calculator 15 and the phase calculator I6 and inputted to the 10th order °C.
are provided, a subtracter 11b, an integrator 12b, a divider 13b
and subtractors 11e, respectively.

The output of the divider zsb is provided corresponding to the integrator 12a and the divider 13a, and the output of the divider zsb is also manually inputted to the phase wave pf unit 16.

In such a device, the instants of the real part X'' and imaginary part XI of the Fourier spectrum can be calculated from the vibration data X converted into digital quantities and the time phase θ of the frequency to be analyzed determined from the reference signal P such as a rotation signal using the following equation. The value division multipliers 10a and 10b each calculate 0 and 1.

From this four-hour value (xR+x'), the average value (XR, XI
) 7 (reduction. 511a, removed with 1 l b,
The products are multiplied by integrators 12a and 12b.

This integral value XR, XT is divided by the f constant, a divider 13a,
13b, the average value XR is applied to an amplitude calculator 15 and a phase calculator η, and an error amplitude X and a phase angle ψ are determined and applied to the amplifier I6.

In the trigonometric function generator I4, the time phase θ of the frequency to be analyzed is determined from the reference signal P, and the phase θ is STN.

is calculated and output to multipliers 10a and 10b.

In the case of frequency analysis of an integral multiple of the rotational speed fr of a rotating body, such as ship vibration, the sampling frequency 16 is set to fa −−Nc −f−Ne ・fr ・Np
−・”f8) However, when setting the analysis frequency f = fr−Ns, θ+ = 2 rr 1/Ne H+・
+++ (91, Nc C(G O',
SI+'θ1I7) without preparing ce phase data table]
Good.

Such a device ((according to which, the following effects can be achieved and Zl
.

(1) It is possible to perform continuous 7-layer transformation across all data intervals.

(2) M analysis response frequency (frequency resolution) It is sufficient to simply change the constant K.

(3) Time series data memory and spectral data memory are no longer required.

An embodiment in which the present invention is applied to a control system for a ship vibration damper will be described. In FIG. 3, an analog ship vibration signal '
iA/D converter 22a.

22b, the A/D converter 22a converts the hull vibration signal to digital 1 based on the rotation signal of the propeller shaft 29 detected by the rotation signal detector 25aK, and converts the hull vibration signal to digital 1. 11 force of vessel 22a and propeller shaft 2
The rotation signal of 9 is converted to the continuous Fourier transformer 2.1 according to the present invention.
input to a.

The continuous Fourier transformer 23a calculates the amplitude of the rotation order component of the set propeller shaft 29 using the rotation signal as a phase reference 2).

What is the set order number of holes? In the case of JE number t: Continuous Fourier transformers 2JB are provided for the number of orders, and their output is constantly monitored by the set order cauterizer 24, and when the vibration amplitude exceeds the set level, the order is output.

In response to this output, the flywheel 28 of 4J@2t;
], and the flywheel 28 rotation signal 1 is output.
525b and the rotation signal of the propeller shaft 29 The rotation signal of the detector 251L and the damper 26
is controlled so that it is multiplied by the set order.

When the rotation speed of the flywheel 28 is synchronized with the propeller 2 shaft 29, the flywheel 2θσ] rotation signal detector 2
5 h 17) Ship vibration detector/
A/D conversion (22b) L, continuous Fourier transformation (23), and determine the vibration amplitude of the set order component and the phase difference from the rotation signal.

This phase difference l13 force is input to the phase control section 27b of the vibration damper 26, and is controlled so that the hull vibration caused by the excitation force of the flywheel 28 is in the opposite phase to the hull vibration detected by the hull vibration detector 2JjF. .

: The &IrIJJ amplitude output is input to the excitation force control section 27c of the vibration damper 26, and the excitation force is adjusted so that the ship's vibration is minimized. The frequency resolution device incorporated as a control device for a hull vibration damper needs to match its response frequency to the optimum time constant of the control device, and it is also necessary to frequency-analyze continuous data and continuously obtain amplitude and phase information. Therefore, the conventional frequency analyzer 1i using fast Fourier transform is inappropriate.

In short, according to the present invention, the multiplier 1 includes the trigonometric function generator 14 inputting the reference signal P, and the multiplier 1 inputs the output of the trigonometric function generator 14 in which one series is the vibration data τl.
0a, the output of the same multiplier IOa, and the divider J3a, which will be described later.
The output of the subtractor 11a is input to the integrator 12n, and the output of the integrator J2a is all input to the division W q! e 7 s a, the other series is constructed in the same way as the one series, and the outputs of the dividers 13 B, , 1.91) are inputted in phase with the 71st IBaHT unit I5. The present invention provides a frequency analyzer that can arbitrarily set the frequency resolution. 4,
It is extremely useful for industry.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a known frequency analysis method 4/2, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is a block diagram showing the method of controlling a hull vibration damper according to the present invention. 10a, 10b...multipliers, 11a, 11h which is a Glock diagram showing an example applied to the system.
-=Reducer 17, 12P, 7. ? h=4fi divider, 1
3a. 13b...Divider, 14...Trigonometric function generator, I5...
- Shake 11J calculator, J6... Phase calculator, 21... Hull Jlar J) detector, 22 a, 22 b
-= A, /D converter, 2, ? Fl, 2.1
h... Continuous Fourier switch, 24°゛ setting order calculator, 2s s, , 2s h... Rotation signal detection 1 ()
device, 26... vibration damping F, 27 a... speed control section, 27
b... Phase production section, 27c... Excitation force control section, 28
...Flywheel, 29...Propeller shaft. Patent Attorney, Suzue 1 (, Hiko Figure 1 Figure 2

Claims (1)

[Claims] Trigonometric function generator (14
), and one series inputs the vibration data (Xt) and the output of the trigonometric function generator (14), a multiplier (J(7)
a), a subtractor (JJa) that inputs the output of the multiplier (10a) and the output of the subtractor (z3a), which will be described later, and an integrator that inputs the output of the subtractor (JJa). (12a) and a divider (13a) that inputs the output of the same integrator (L2R).
), and the other series is constructed in the same way as the one series, and divides the outputs of the η divider (13a) and (zsb), respectively.
).