JPS6147521A - Apparatus for measuring attenuation ratio - Google Patents
Apparatus for measuring attenuation ratioInfo
- Publication number
- JPS6147521A JPS6147521A JP16899984A JP16899984A JPS6147521A JP S6147521 A JPS6147521 A JP S6147521A JP 16899984 A JP16899984 A JP 16899984A JP 16899984 A JP16899984 A JP 16899984A JP S6147521 A JPS6147521 A JP S6147521A
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- band pass
- data
- pass filter
- attenuation ratio
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H17/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves, not provided for in the preceding groups
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
Description
【発明の詳細な説明】
〔就業上の利用分野〕
本発明は減衰比計測装置に係や、特にコヒーレンス特性
が悪い振動系、例えば丸棒等の周期データカ)らも精度
良く減衰比を計測することができる減衰比計測装置に関
する。[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a damping ratio measuring device, and is particularly applicable to measuring the damping ratio of a vibration system with poor coherence characteristics, such as periodic data such as a round bar, with high accuracy. The present invention relates to a damping ratio measuring device that can measure damping ratios.
従来では、振動系を加振しで加速度等の時間変化に関す
る周期データを検出し、出力へと入力Fとの比で表わさ
れる伝達特性A / F、すなわちモビリティ(レベル
)の周波数freqに対する変化を求め、第2図に示す
ように着目した周波数(例えば、共振点)fiのモビリ
ティよ、り 3 dB低いモビリティの周波数f u
s f L k求め、以下の式に基づいて減衰比ζを求
めていた。Conventionally, a vibration system is vibrated to detect periodic data related to time changes such as acceleration, and the transfer characteristic A / F expressed as the ratio of the input F to the output, that is, the change in mobility (level) with respect to the frequency freq is calculated. As shown in Fig. 2, the frequency of mobility f u is 3 dB lower than the mobility of the focused frequency (e.g., resonance point) fi.
s f L k was determined, and the damping ratio ζ was determined based on the following formula.
しかしながら、かかる従来の減衰比計測方法では、着目
した周波数においてコヒーレンス特性が悪いと着目した
周波数fiにおけるモビリティを精度よく求められkい
ため、3dB低い周波afu、f+、の値も精度が悪く
、結果として減衰比の精度が悪くなる、という問題がb
つだ。すなわち、第2図には、共振点において破線で表
すコヒーレンス関数が0に近い値になシ、コヒーレンス
特性が悪い状態を示すが、周波数f1においてコヒーレ
ンス特性が非常に悪くなっているため、周波数fiにお
けるモビリティの精度が悪く、従って減衰比の精度も悪
くなっている。However, in such conventional attenuation ratio measurement methods, if the coherence characteristic is poor at the focused frequency, it is difficult to accurately determine the mobility at the focused frequency fi, so the value of the frequency afu, f+, which is 3 dB lower, is also inaccurate, and as a result, The problem that the accuracy of the damping ratio deteriorates is b.
Tsuda. That is, in FIG. 2, the coherence function represented by the broken line at the resonance point has a value close to 0, indicating a state in which the coherence characteristics are poor, but the coherence characteristics are very poor at the frequency f1, so The accuracy of the mobility is poor, and therefore the accuracy of the damping ratio is also poor.
本発明は上記問題点を解決するために、モビリティに関
係しない周波数に着目して成されたもので、時間変化に
関する振動系の周期データ金検出する検出手段と、前記
周期データを7−リエ変換して伝達特注全演算する変換
手段と、前記伝達特性の実数部データのうち着目し九周
波数を中心周波数とする所定周波数帯域のデータのみ通
過させる帯域通過手段と、前記帯域通過手段を通過した
データの最大値を示す周波数および最小値を示す周波数
を求め、前記最大!を示す周波数および前記最小値を示
す周波数に基づいて減衰比を演算する演算手段と、を含
んで構成したものである。In order to solve the above-mentioned problems, the present invention has been made by focusing on frequencies unrelated to mobility, and includes a detection means for detecting periodic data of a vibration system related to time changes, and a 7-lier transform of the periodic data. converting means for performing all custom transmission calculations; band-passing means for passing only data in a predetermined frequency band centered on the nine frequencies of the real part data of the transfer characteristic; and data passed through the band-passing means. Find the frequency that shows the maximum value and the frequency that shows the minimum value, and then calculate the maximum ! and calculation means for calculating the damping ratio based on the frequency representing the minimum value and the frequency representing the minimum value.
〔作用〕
次に本発明の詳細な説明する。鮮3因に示すように、1
自由度のばね質量ダッシュポット系の運動方程式は次の
ように表わされる。[Function] Next, the present invention will be explained in detail. As shown in the three causes of freshness, 1
The equation of motion of the spring-mass-dashpot system with degrees of freedom is expressed as follows.
M″x”+cx+Kx=f ・・・・・・・・・
・・・(2)ただし、Mは質量、Cは減衰係数、Kはば
ね定数、fは外力、Xは変位、士、iは各々Xの時間t
に関する1階微分、2階微分である。M″x”+cx+Kx=f ・・・・・・・・・
...(2) where M is the mass, C is the damping coefficient, K is the spring constant, f is the external force, X is the displacement, and i is the time t of each X.
These are the first-order differential and the second-order differential with respect to.
ここで、x=×ejw1(ただし、j = v”T 、
wは周波数でおる)として(2)式を変形すると、次
の(3)式になる。Here, x=×ejw1 (however, j=v”T,
When formula (2) is transformed by assuming that w is the frequency, the following formula (3) is obtained.
(Mv7+K ) X ejWt+jcwX e jw
′t=F = (3)次にA=蔓としてA/Fi求め
ると次のようになる。(Mv7+K) X ejWt+jcwX e jw
't=F=(3) Next, when A=vine, A/Fi is calculated as follows.
上記(4)式は、周波数Wを変数とする関数で表わされ
ておシ、また入は出力に対応し、Fは入力に対応するか
ら、上記(4)式は出力のフーリエ変換形と入力の7−
リエ変換形との比で示される伝達関数Gを表わすことに
なる。Equation (4) above is expressed as a function with frequency W as a variable, and since input corresponds to output and F corresponds to input, Equation (4) above is the Fourier transform form of output. Input 7-
This represents a transfer function G expressed as a ratio to the Rie transform form.
上記(4)式の束数部をpとし、この実数部pを周波数
Wに関して微分すると次のようになる。Let p be the bundle number part of the above equation (4), and differentiate this real number part p with respect to the frequency W, as follows.
ここで、dp/dw=0となるwt求める。振動系は振
動していることよ、り W ”−、Oであるがら、dp
/dw=o となるためには、次の式を満足する必要
がある。Here, wt such that dp/dw=0 is determined. Since the vibration system is vibrating, W ”-, O, dp
/dw=o, it is necessary to satisfy the following equation.
M(KM−C”)v’−2MK”が十KB=0 ・・・
・・・・・・(6)w”=r としたときの2矢方程式
の根rt、rzt求めると、
上記(7)、(8)式より、
ところで、臨界減衰係数Ccは、
cc=2Vi[・・・・・・・・・・・・・・・(lO
)と表わされるから、上記(9)式は次のようになシ、
減衰比を表わすことになる。M(KM-C")v'-2MK" is 10KB=0...
・・・・・・(6) When we calculate the roots rt and rzt of the two-arrow equation when w”=r, From the above equations (7) and (8), By the way, the critical damping coefficient Cc is cc=2Vi [・・・・・・・・・・・・・・・(lO
), the above equation (9) can be written as:
It represents the damping ratio.
上記(11)式において、rl”W1!、r2=W2”
であるから、減衰比ζは次のように表わされる。In the above equation (11), rl"W1!, r2=W2"
Therefore, the damping ratio ζ is expressed as follows.
wl”−W2友
ζ=□ ・・・・曲・・・曲 (12)ws ” +
w22
上記では、l自由度の振動系について考えたが、一般の
多自由度の振動系の振動特性は、l自由度振動系の振動
特性の重ね合せと考えられ、逆に多自由度振動系の特定
周波数帯域の@達特性に着目すれば、1自由度の振動系
と考えられるから、多自由度振動系についても上記の原
理を適用すれば減衰比を求めることができる。wl”-W2 friend ζ=□ ... song... song (12) ws ” +
w22 In the above, we considered a vibrating system with l degrees of freedom, but the vibration characteristics of a general vibrating system with many degrees of freedom can be considered to be a superposition of the vibration characteristics of vibrating systems with l degrees of freedom, and vice versa. If we focus on the @-reaching characteristic in a specific frequency band, it can be considered as a vibration system with one degree of freedom, so if we apply the above principle to a vibration system with multiple degrees of freedom, we can find the damping ratio.
本発明は上記原理に基づいて減衰比を計測するものであ
り、検出手段によって時間変化に関する振動系の周期デ
ータを検出し、変換手段によって周期データf 7−
IJ x変換して上記(4)式に示す伝達特性を演算し
、帯域通過手段によって伝達特性の実数部データのうち
着目した周波数を中心周波数とする所定周波数帯域のデ
ータのみ通過させ、演算手段によって帯域通過手段を通
過したデータの最大値を示す周波数および最小値を示す
周波数を求め上記(12)式により減衰比を演算するよ
うにしたものである。ここで、伝達特性を演算するため
に、入力として加速度のデータを用いる必要があるが、
検出手段が変位の周期データを検出する場合には2階微
分することによル、また検出手段が速度の周期データを
検出する場合には1階微分することによシ、加速度のデ
ータに変換することができる。The present invention measures the damping ratio based on the above principle, in which the detection means detects the periodic data of the vibration system regarding time changes, and the conversion means converts the periodic data f7-
The transfer characteristic shown in equation (4) above is calculated by converting the IJ The frequency indicating the maximum value and the frequency indicating the minimum value of the data passed through the band pass means are determined, and the attenuation ratio is calculated using the above equation (12). Here, in order to calculate the transfer characteristics, it is necessary to use acceleration data as input,
When the detection means detects periodic data of displacement, it is converted to acceleration data by second-order differentiation, and when the detection means detects periodic data of velocity, it is converted to acceleration data by first-order differentiation. can do.
〔51!施例〕
以下第1図を参照して本発明の一実施例を詳細に説明す
る。本実施例は、自動車の車体等の減衰比を計測するの
に好適である。[51! Embodiment] An embodiment of the present invention will be described in detail below with reference to FIG. This embodiment is suitable for measuring the damping ratio of an automobile body, etc.
加速度計2は、振動基土に取付けられて、時間変化に関
する周期データとして加速度を検出する。The accelerometer 2 is attached to the vibrating base and detects acceleration as periodic data regarding time changes.
この加速度計2から出力−される信号は第1図の(A)
に示すように時間軸のデータになる。この加速度計2は
、マイクロプロセッサで構成されたフーリエ変換器4に
接続されている。このフーリエ変換器4は、従来と同様
の構成で、入力された時間軸のデータを高速7−リエ変
換し、周波数軸のデータとして伝達特性を演算するもの
であシ、この伝達特性の実数部データは第1図(B)に
示すようになる。フーリエ変換器4の実数部データ出力
端には、中心周波数fit−可変に設定できるバンドパ
スフィルタ6が接続されている。バンドパスフィルタの
中心周波数t−着目した周波数に設定すると、バンドパ
スフィルタ6から、第1図(C)に示すように、着目し
た周波数を中心周波数とする所定帯域の信号が出力され
る。バンドパスフィルタ6の出力端には、中央処理装置
(CPU)8が接続さレテおシ、CPU8はバンドパス
フィルタ6から入力された周波数軸のデータを周波数に
関して微分し、その微分係数が0となる周波数wl 、
Wl f求め、上記(12)式に基づいて減衰比ζを
演算する。The signal output from this accelerometer 2 is shown in (A) in Figure 1.
The data is on a time axis as shown in . This accelerometer 2 is connected to a Fourier transformer 4 comprised of a microprocessor. This Fourier transformer 4 has the same configuration as the conventional one, and performs high-speed 7-lier transform on the input time axis data and calculates the transfer characteristic as frequency axis data. The data is as shown in FIG. 1(B). A bandpass filter 6 whose center frequency fit can be set variably is connected to the real part data output terminal of the Fourier transformer 4. When the center frequency t of the band-pass filter is set to the focused frequency, the band-pass filter 6 outputs a signal of a predetermined band having the focused frequency as the center frequency, as shown in FIG. 1(C). A central processing unit (CPU) 8 is connected to the output end of the bandpass filter 6. The CPU 8 differentiates the frequency axis data input from the bandpass filter 6 with respect to frequency, and the differential coefficient is 0. The frequency wl,
Wl f is determined, and the damping ratio ζ is calculated based on the above equation (12).
そして、CPU8・で演算された減衰比ζは、ディスプ
レイ装置12または7′リンク10に表示される。Then, the attenuation ratio ζ calculated by the CPU 8 is displayed on the display device 12 or the 7' link 10.
すなわち、減衰比を求めるための周波数(着目した周波
数)′t−バンドパスフィルタに設定し、時間軸のデー
タを入力すれば減衰比が表示される。That is, by setting the frequency for determining the damping ratio (the frequency of interest)'t-band pass filter and inputting time axis data, the damping ratio will be displayed.
なお、上記では加速度計を用い次側について説明したが
、変位針や速度計を用いることもでき、この場合にはフ
ーリエ変換器で加速度のデータに変換されて処理される
。また、7−リエ変換器、バンドパスフィルタおよびC
PUtlつのコンピュータで構成するようにしてもよい
。Although the following explanation has been given above using an accelerometer, a displacement needle or a speedometer may also be used, and in this case, the data is converted into acceleration data using a Fourier transformer and processed. Also, a 7-lier transformer, a bandpass filter and a C
It may be configured with one computer.
以上説明したように本発明は、モビリティに関係しない
周波数金剛いて減衰比を計測しているため、コヒーレン
ス特性が悪い振動系において精度よくかつ簡単に減衰比
を求めることができる、という効果が得られる。As explained above, since the present invention measures the damping ratio at a frequency that is not related to mobility, it is possible to obtain the damping ratio accurately and easily in a vibration system with poor coherence characteristics. .
【図面の簡単な説明】
第1図は本発明の一実施例を示すブロック図、第2図は
従来の減衰比を求める方法を説明するための説明図、m
3図はばね質計ダッシュポット系を示す線図である。
2・・・加速度計、4・・・フーリエ変換器、6・・・
バンドパスフィルタ、8・・・CPU。[Brief Description of the Drawings] Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram for explaining a conventional method of determining a damping ratio, m
Figure 3 is a diagram showing the spring quality meter dashpot system. 2... Accelerometer, 4... Fourier transformer, 6...
Bandpass filter, 8...CPU.
Claims (1)
検出手段と、前記周期データをフーリエ変換して伝達特
性を演算する変換手段と、前記伝達特性の実数部データ
のうち着目した周波数を中心周波数とする所定周波数帯
域のデータのみ通過させる帯域通過手段と、前記帯域通
過手段を通過したデータの最大値を示す周波数および最
小値を示す周波数を求め前記最大値を示す周波数および
前記最小値を示す周波数に基づいて減衰比を演算する演
算手段と、を含む減衰比計測装置。(1) A detecting means for detecting periodic data of a vibration system related to time changes, a converting means for calculating a transfer characteristic by Fourier transforming the periodic data, and a center frequency of a focused frequency of the real part data of the transfer characteristic. a band pass means for passing only data in a predetermined frequency band, and a frequency indicating a maximum value and a frequency indicating a minimum value of the data passed through the band pass means, and a frequency indicating the maximum value and a frequency indicating the minimum value. A damping ratio measuring device comprising: calculation means for calculating a damping ratio based on the above.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP16899984A JPS6147521A (en) | 1984-08-13 | 1984-08-13 | Apparatus for measuring attenuation ratio |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP16899984A JPS6147521A (en) | 1984-08-13 | 1984-08-13 | Apparatus for measuring attenuation ratio |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS6147521A true JPS6147521A (en) | 1986-03-08 |
JPH0357416B2 JPH0357416B2 (en) | 1991-09-02 |
Family
ID=15878471
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP16899984A Granted JPS6147521A (en) | 1984-08-13 | 1984-08-13 | Apparatus for measuring attenuation ratio |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6147521A (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5663218A (en) * | 1979-10-29 | 1981-05-29 | Mitsubishi Heavy Ind Ltd | Transient response analysis method for natural vibration mode |
JPS60122327A (en) * | 1983-12-06 | 1985-06-29 | Mitsubishi Heavy Ind Ltd | Investigating method of load-dependent oscillation of rotary machine |
JPS60122328A (en) * | 1983-12-06 | 1985-06-29 | Mitsubishi Heavy Ind Ltd | Investigating method of rotating speed-dependent oscillation of rotary machine |
-
1984
- 1984-08-13 JP JP16899984A patent/JPS6147521A/en active Granted
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5663218A (en) * | 1979-10-29 | 1981-05-29 | Mitsubishi Heavy Ind Ltd | Transient response analysis method for natural vibration mode |
JPS60122327A (en) * | 1983-12-06 | 1985-06-29 | Mitsubishi Heavy Ind Ltd | Investigating method of load-dependent oscillation of rotary machine |
JPS60122328A (en) * | 1983-12-06 | 1985-06-29 | Mitsubishi Heavy Ind Ltd | Investigating method of rotating speed-dependent oscillation of rotary machine |
Also Published As
Publication number | Publication date |
---|---|
JPH0357416B2 (en) | 1991-09-02 |
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