JPH0313536B2 - - Google Patents
Info
- Publication number
- JPH0313536B2 JPH0313536B2 JP56084743A JP8474381A JPH0313536B2 JP H0313536 B2 JPH0313536 B2 JP H0313536B2 JP 56084743 A JP56084743 A JP 56084743A JP 8474381 A JP8474381 A JP 8474381A JP H0313536 B2 JPH0313536 B2 JP H0313536B2
- Authority
- JP
- Japan
- Prior art keywords
- cable
- tension
- vibration
- voltage
- fundamental frequency
- 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.)
- Expired - Lifetime
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/04—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring tension in flexible members, e.g. ropes, cables, wires, threads, belts or bands
- G01L5/042—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring tension in flexible members, e.g. ropes, cables, wires, threads, belts or bands by measuring vibrational characteristics of the flexible member
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
Description
【発明の詳細な説明】
本発明は、移動中のケーブル張力、特に海底ケ
ーブル布設時のケーブル張力測定に用いる張力計
測装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tension measuring device used to measure cable tension during movement, particularly cable tension during submarine cable installation.
従来、ケーブル張力を測定する方法として、第
１図に示すように、ケーブル１を支点機構２によ
つてその一点を支持し、支点機構２の下部に接し
てロードセル３を設けたものにより測定する方法
がある。すなわちケーブル張力Ｔによつて支点機
構を介してロードセルに加わる圧縮力Ｗは、ケー
ブルの張る角度θ1，θ2に応じて
Ｗ＝Ｔ（sinθ1＋sinθ2）
となるが、この関係により、計測した圧縮力Ｗか
らケーブル張力Ｔを得るものである。しかしなが
らこの方法では、ケーブルの自重、鉛の動揺のた
め、ケーブル張力に依存してケーブルの張る角θ
が変動することと、支点機構２の自重とケーブル
の自重により特に船の動揺に応じて慣性力がロー
ドセル３に作用する点で測定の誤差が大きい。 Conventionally, as shown in FIG. 1, a method of measuring cable tension is to support a cable 1 at one point by a fulcrum mechanism 2, and measure it by installing a load cell 3 in contact with the lower part of the fulcrum mechanism 2. There is a way. In other words, the compressive force W applied to the load cell via the fulcrum mechanism due to the cable tension T becomes W=T (sinθ 1 +sinθ 2 ) depending on the tension angles θ 1 and θ 2 of the cable. Based on this relationship, the measurement The cable tension T is obtained from the compressive force W. However, with this method, the angle θ of the cable depends on the cable tension due to the weight of the cable and the sway of the lead.
The measurement error is large because of fluctuations in the load cell 3 and the inertial force acting on the load cell 3 due to the weight of the fulcrum mechanism 2 and the weight of the cable, especially in response to the movement of the ship.
この他に、ケーブルをその固有または基本周波
数で振動するよう励振し、ケーブルの振動周波数
を張力の表示として測定する方法が提案されてい
る。またケーブルを励振する機構も従来から幾つ
か提案されているが、何れも装置が複雑で消費電
力も大きかつた。特に海底ケーブルのように大径
で重量も大きく、振れや振動のある船上において
張力測定を行なう場合に対して、ケーブルをその
固有または基本周波数で振動するよう励振するこ
とは極めて困難である。 Other methods have been proposed in which the cable is excited to vibrate at its natural or fundamental frequency and the vibrational frequency of the cable is measured as an indication of tension. In addition, although several mechanisms for exciting cables have been proposed in the past, they all require complicated devices and consume a large amount of power. It is extremely difficult to excite the cable to vibrate at its natural or fundamental frequency, especially when measuring tension on a ship such as a submarine cable, which has a large diameter and weight, and is subject to shaking and vibration.
本発明は海底ケーブル（以下単にケーブルとい
う。）を布設する作業船に搭載し、布設状況を監
視するための簡易な小形のケーブル張力計測装置
であり、ケーブルを励振することなく、布設中の
ケーブルに恒常的に生じている微小振幅の複合振
動をケーブルに接触することなく検出し、この中
よりろ波器によつてケーブル振動の基本周波数成
分を抽出して、これよりケーブル張力を得るよう
にしたケーブル張力計測装置を提供するものであ
つて、以下図面について詳細に説明する。 The present invention is a simple and compact cable tension measuring device that is installed on a work boat that installs submarine cables (hereinafter simply referred to as cables) and monitors the installation status. The system detects the small amplitude complex vibrations that constantly occur in the cable without contacting the cable, extracts the fundamental frequency component of the cable vibration using a filter, and obtains the cable tension from this. The present invention provides a cable tension measuring device according to the present invention, which will be described in detail with reference to the drawings below.
第２図は本発明の実施例であつて、４，５は間
隔を隔てて配設されたケーブル１の支持部材であ
る。６は光学的変位計よりなる非接触形振動測定
器であつて、この振動測定器６はケーブルの側面
と背景との間にできる明暗のエツジのケーブル長
手方向に垂直な方向の変位を計測すするように配
設することによつてケーブルの移動中その微小振
動を検出できる。８は検出された振動の波形か
ら、支持部材４，５間のケーブル部分の基本周波
数のみを抽出する低周波ろ波器である。９はろ波
器８で抽出されたケーブル部分の基本周波数から
ケーブル張力値に変換する周波数−張力変換器で
あつて、周波数に比例した電圧に変換する周波数
−電圧変換器９ａと、この変換器９ａで変換され
た電圧を自乗してケーブル張力値に比例した値と
するための自乗増幅器９ｂと、ケーブル種類毎
の、ケーブル張力と固有振動数との関係で決る定
数を予め入力した定数選択器９ｃと、張力表示部
９ｄとよりなる。 FIG. 2 shows an embodiment of the present invention, in which numerals 4 and 5 are support members for the cable 1 arranged at intervals. 6 is a non-contact vibration measuring device consisting of an optical displacement meter, and this vibration measuring device 6 measures the displacement in the direction perpendicular to the longitudinal direction of the cable of the bright and dark edges formed between the side surface of the cable and the background. By arranging the cable in such a way that the cable is moved, minute vibrations of the cable can be detected. 8 is a low frequency filter that extracts only the fundamental frequency of the cable portion between the supporting members 4 and 5 from the detected vibration waveform. Reference numeral 9 denotes a frequency-tension converter that converts the fundamental frequency of the cable portion extracted by the filter 8 into a cable tension value, and a frequency-voltage converter 9a that converts the fundamental frequency of the cable portion extracted by the filter 8 into a voltage proportional to the frequency; a square amplifier 9b for squaring the voltage converted to a value proportional to the cable tension value; and a constant selector 9c into which a constant determined by the relationship between cable tension and natural frequency for each cable type is input in advance. and a tension display section 9d.
つぎにこのような構成よりなる張力計測装置の
動作を説明する。 Next, the operation of the tension measuring device having such a configuration will be explained.
両支持部材４，５間におけるケーブル１の長手
方向に垂直な方向のケーブル偏位を検出する振動
測定器６によれば、ケーブルの移動中に生ずる微
小振動を検出することができる。 The vibration measuring device 6, which detects cable deviation in a direction perpendicular to the longitudinal direction of the cable 1 between the supporting members 4 and 5, can detect minute vibrations that occur during movement of the cable.
このように検出されるケーブルの振動には、船
体のエンジン、動揺のような外力による振動、支
持部材４，５間に挾まれた測定区間以外から伝播
して来る振動、ケーブル走行に伴なう振動などが
複合的に含まれている。その中から基本周波数の
みをろ波器８によつて抽出することは容易であ
る。 Cable vibrations detected in this way include vibrations caused by external forces such as the engine of the ship or shaking, vibrations propagating from sources other than the measurement section sandwiched between the support members 4 and 5, and vibrations associated with cable running. Contains multiple vibrations. It is easy to extract only the fundamental frequency from it using the filter 8.
本願発明の対象としている海底ケーブルの場合
にはそれまでの布設作業の経験から海底ケーブル
の自重と布設海域の水深とから作業船上における
ケーブル張力が略予測できる。したがつて前記複
合的振動からその基本周波数成分を抽出するため
には、予め想定されるケーブル張力から計算され
るケーブル振動の基本周波数を中心としてある帯
域幅をもたせた周波数範囲にろ波器８の通過帯域
を設定して置けば良い。このような手順によつて
予想張力に近い値の実際のケーブル張力によつて
決まる振動周波数を他の周波数成分から分離して
抽出することができる。ろ波器８によつて抽出さ
れた基本周波数は、周波数−電圧変換器９ａでそ
の周波数に比例した電圧に変換され、この電圧が
自乗増幅器９ｂで自乗されてケーブル張力値に比
例した値となる。一方ケーブル種類毎のケーブル
張力と固有振動数の関係で決る定数を定数選択器
９ｃに入力しておき、そのときのケーブル種類に
応じた比例定数を選ぶようにすると、張力表示部
９ｄにはケーブル張力が表示される。 In the case of submarine cables, which are the object of the present invention, the cable tension on the work vessel can be approximately predicted from the own weight of the submarine cable and the water depth of the installation sea area based on previous experience in installation work. Therefore, in order to extract the fundamental frequency component from the complex vibration, a filter 8 is used to filter a frequency range having a certain bandwidth around the fundamental frequency of the cable vibration calculated from the cable tension assumed in advance. All you have to do is set the passband of . Such a procedure allows the vibration frequencies determined by the actual cable tension, which are close to the expected tension, to be extracted separately from other frequency components. The fundamental frequency extracted by the filter 8 is converted into a voltage proportional to the frequency by a frequency-voltage converter 9a, and this voltage is squared by a square amplifier 9b to obtain a value proportional to the cable tension value. . On the other hand, if a constant determined by the relationship between cable tension and natural frequency for each cable type is input into the constant selector 9c, and a proportional constant corresponding to the cable type at that time is selected, the tension display section 9d Tension is displayed.
第３図に示すように、船上からポリエチレン外
被の外径25mm、重量0.01Kg／cmの海底ケーブル１
の布設時に、支持部材４，５間の距離を6.3ｍと
し、非接触式の振動測定器６を図のように配置し
てケーブル張力の測定実験を行なつ結果から得
た、ケーブル張力とケーブル振動の基本周波数と
の関係と、同様の関係を次式で計算した計算値と
を第４図に示す。ケーブル張力の計測は、ケーブ
ル先端が海底面に着底しないで海中に自重で垂れ
下がつた状態の時に行なつた。 As shown in Figure 3, a submarine cable 1 with a polyethylene jacket outer diameter of 25 mm and a weight of 0.01 kg/cm is
When installing the cable, the distance between the supporting members 4 and 5 was set to 6.3 m, and the cable tension was measured by placing the non-contact vibration measuring device 6 as shown in the figure. FIG. 4 shows the relationship with the fundamental frequency of vibration and the calculated value obtained by calculating the similar relationship using the following equation. The cable tension was measured when the tip of the cable was hanging down under its own weight without touching the seabed.
ただし、ｆは基本周波数、は支持部材間距離
（630cm）、γはケーブルの単位長重量（0.01Kg／
cm）、ｇは重力の加速度（980cm／sec2）である。 However, f is the fundamental frequency, is the distance between supporting members (630cm), and γ is the weight per unit length of the cable (0.01Kg/
cm), g is the acceleration of gravity (980 cm/sec 2 ).
上記の実験結果から、ケーブル張力がケーブル
の振動の基本周波数の自乗によい精度で比例し、
測定値と計算値とがよく一致していることが確か
められた。 From the above experimental results, the cable tension is proportional to the square of the fundamental frequency of the cable vibration with good accuracy.
It was confirmed that the measured values and calculated values were in good agreement.
第５図は上記の実験において、ケーブルの自由
振動波形を計測した結果の一例を示し、またこの
波形を周波数分析した結果を第６図に示す。波、
うねりにより動揺し、またエンジン等により振動
する船上で、ケーブルに特別な励振を施さずにケ
ーブル振動の基本周波数を確実に把握することが
できた。 FIG. 5 shows an example of the results of measuring the free vibration waveform of the cable in the above experiment, and FIG. 6 shows the results of frequency analysis of this waveform. wave,
On a ship that is shaken by swells and vibrates due to engines, etc., we were able to reliably determine the fundamental frequency of cable vibration without applying any special excitation to the cable.
以上のように本発明によれば、ケーブルを強制
的に振動することなく、二つの支持部材間におい
てケーブルに生じている微小振幅からケーブル張
力を精度よく計測し得る。従つて海底ケーブルの
ような大口径で非常に高い張力を受けるものにお
いても簡単、安全に、また測定のために外被に損
傷を与えることなく測定することができ、ケーブ
ル布設工事の安全性向上、布設制御の向上による
経済化を図ることができる。 As described above, according to the present invention, the cable tension can be accurately measured from the minute amplitude generated in the cable between two supporting members without forcibly vibrating the cable. Therefore, even cables with large diameters and subject to extremely high tension, such as submarine cables, can be measured easily and safely, and without damaging the outer sheath, improving the safety of cable installation work. , economicalization can be achieved by improving installation control.
第１図は従来の海底ケーブル張力測定方法の説
明図、第２図は本発明の実施例の構成図、第３図
は本発明による海底ケーブル布設時のケーブル張
力測定実験状態の説明図、第４図は第３図に示す
状態で実験した結果から得たケーブル張力とケー
ブル振動の基本周波数との関係およびこれらの関
係の計算式による計算値とを示す曲線図、第５図
は第３図に示す状態でのケーブル張力測定時のケ
ーブルの自由振動波形図の一例、第６図は第５図
の波形の波形分析図である。
１……ケーブル、４，５……支持部材、６……
振動測定器、８……ろ波器、９……周波数−張力
変換器、９ａ……周波数−電圧変換器、９ｂ……
自乗増幅器、９ｃ……定数選択器、９ｄ……張力
表示器。
FIG. 1 is an explanatory diagram of a conventional submarine cable tension measurement method, FIG. 2 is a configuration diagram of an embodiment of the present invention, and FIG. 3 is an explanatory diagram of an experimental state of cable tension measurement during submarine cable installation according to the present invention. Figure 4 is a curve diagram showing the relationship between the cable tension and the fundamental frequency of cable vibration obtained from the results of the experiment under the conditions shown in Figure 3, and the calculated values using the formula for these relationships. An example of a free vibration waveform diagram of a cable when measuring cable tension in the state shown in FIG. 6 is a waveform analysis diagram of the waveform of FIG. 5. 1... Cable, 4, 5... Support member, 6...
Vibration measuring device, 8... Filter, 9... Frequency-tension converter, 9a... Frequency-voltage converter, 9b...
Square amplifier, 9c... Constant selector, 9d... Tension indicator.
Claims (1)
間隔の隔つた二個所でそれぞれ支持する支持部材
と、これら両支持部材間で支持される前記海底ケ
ーブルの長手方向と直交する方向の微小振動を前
記海底ケーブルに接触することなく検出するケー
ブル振動測定器と、該振動測定器で検出したケー
ブル振動信号の基本周波数成分のみを抽出するろ
波器と、該ろ波器で抽出したケーブル振動の基本
周波数を該基本周波数に比例した電圧に変換する
周波数−電圧変換器、該電圧変換器で変換された
電圧をケーブル張力値に比例変換するための前記
電圧の自乗増幅器、ケーブル種類毎のケーブル張
力と固有振動数との関係で決まる定数を予め入力
した定数選択器および張力値を表示する張力表示
部よりなる周波数−張力変換器とを備えたことを
特徴とする海底ケーブル張力計測装置。1. A support member that supports the submarine cable portion whose tension is to be measured at two locations separated from each other, and a microvibration in a direction perpendicular to the longitudinal direction of the submarine cable supported between these two support members. A cable vibration measuring device that detects cable vibration without contacting the cable, a filter that extracts only the fundamental frequency component of the cable vibration signal detected by the vibration measuring device, and a filter that extracts only the fundamental frequency component of the cable vibration signal extracted by the filter. A frequency-voltage converter for converting the voltage into a voltage proportional to the fundamental frequency, a square amplifier of the voltage for proportionally converting the voltage converted by the voltage converter into a cable tension value, and cable tension and natural vibration for each cable type. What is claimed is: 1. A submarine cable tension measuring device comprising: a constant selector into which a constant determined in relation to a number is input in advance; and a frequency-tension converter comprising a tension display section that displays a tension value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56084743A JPS57199928A (en) | 1981-06-02 | 1981-06-02 | Measuring device for cable tension |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56084743A JPS57199928A (en) | 1981-06-02 | 1981-06-02 | Measuring device for cable tension |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57199928A JPS57199928A (en) | 1982-12-08 |
| JPH0313536B2 true JPH0313536B2 (en) | 1991-02-22 |
Family
ID=13839165
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56084743A Granted JPS57199928A (en) | 1981-06-02 | 1981-06-02 | Measuring device for cable tension |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57199928A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6129728A (en) * | 1984-07-20 | 1986-02-10 | Mitsubishi Heavy Ind Ltd | Tension measuring method |
| US4565099A (en) * | 1984-09-04 | 1986-01-21 | Smiser Industries, Inc. | Method and apparatus for determining tension in a cable |
| JPS62261937A (en) * | 1986-05-09 | 1987-11-14 | Mitsubishi Motors Corp | Measuring instrument for belt tension |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56154636A (en) * | 1980-04-30 | 1981-11-30 | Dainichi Nippon Cables Ltd | Method of measuring tension of wire |
-
1981
- 1981-06-02 JP JP56084743A patent/JPS57199928A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57199928A (en) | 1982-12-08 |
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