JP2002302385A - Overload preventive method and device of suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overload preventive method and a device of a suspension device capable of preventing cutting of a rope body by surely avoiding an overload applied to the rope body such as a cable for suspending and supporting a suspending object when performing work by suspending the suspending object in the sea. SOLUTION: This overload preventive method of the suspension device (an observing device 3) is arranged on a deck 2, and performs the work by overhanging to the side of a hull 1, and suspending the suspending object in the sea. Depression and elevation operation of the suspension device is controlled so that a distance A0 between a delivery position of the rope body and a virtual reference sea surface L is held constant in response to swinging of the hull 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for preventing a suspension device from being overloaded.

[0002]

2. Description of the Related Art For example, when conducting a seabed survey in the deep sea, an observation device 3 installed on a deck 2 of a hull 1 as shown in FIG. Observation equipment (suspended object) is suspended from the tip of the hull 1 to the side of the hull 1 through the cable 4 (cord-like body) under the sea, and observation is performed.

In the observation device 3 shown here, a turning frame 6 is provided so as to be turnable above a fixed post 5 erected on the deck 2, and a main boom 7 is raised on the turning frame 6. An auxiliary boom 8 is pivotally connected to the tip of the main boom 7 so as to be freely swingable. The main boom 7 and the auxiliary boom 8 constitute a jig 9 of a folding type.

A hydraulic cylinder 10 for raising and lowering the main boom 7 is provided between the turning frame 6 and the main boom 7, and between the main boom 7 and the auxiliary boom 8. A swing hydraulic cylinder 11 for swinging the auxiliary boom 8 with respect to the main boom 7 is provided, and the lifting hydraulic cylinder 10 is responsible for the lifting operation of the main jib 9.

A cable 4 fed from a winch drum (not shown) is connected to a sheave 12 of a revolving frame 6.
And the sheave 13 at the tip of the main boom 7 and the sheave 14 at the tip of the auxiliary boom 8, which are suspended from the tip of the jib 9. The cable 4 allows the observation equipment to be hung deep underwater. Has become.

Here, when working on the sea using this type of observation device 3, the hull 1 swings under the influence of waves, and the tip of the jib 9 of the observation device 3 is caused by the swing. Since the cable 4 is largely moved up and down, the cable 4 is severely fluctuated, and in the worst case, the cable 4 is cut, and there is a possibility that expensive observation equipment and the cable 4 may be lost.

For this reason, conventionally, an overload prevention device as shown in FIG. 5 is provided, and in the overload prevention device shown in FIG. An accumulator 15 provided in the vicinity of the hydraulic cylinder 10 for lifting,
The hydraulic oil 16 introduced into the accumulator 15 is pressurized and held by a nitrogen gas 18 via a piston 17. The accumulator 15 is appropriately replenished via a blower 20 from a plurality of nitrogen cylinders 19 arranged at required places and sealed.

If such an overload prevention device is employed, the accumulator 15 will function as a shock absorber (damper) by compressing the nitrogen gas 18. When the tip of the jib 9 of FIG. 3 is largely displaced upward and the tension applied to the cable 4 is significantly increased, a large pull-down force acts on the jib 9. At this time, the nitrogen gas 18 of the accumulator 15 The hydraulic oil 16 flows into the accumulator 15 from the expansion-side oil chamber of the hydraulic cylinder 10 for compression, and the hydraulic cylinder 10 for elevation is shortened.
The jib 9 tilts in the falling direction following the pulling force,
Thus, the overload on the cable 4 is absorbed.

Conversely, when the tip of the jib 9 is displaced downward and the tension applied to the cable 4 is reduced, the nitrogen gas 18 of the accumulator 15 expands and the lowering of the accumulator 15 from the accumulator 15 side. The hydraulic oil 16 is returned to the oil chamber on the extension side of the hydraulic cylinder 10 and the hydraulic cylinder 1 for elevating
Since the extension 0 is operated, the jib 9 is tilted in the upright direction, the slack of the cable 4 is absorbed, and the tension of the cable 4 is maintained in an appropriate range.

[0010]

However, in such a conventional overload prevention device, as a result of the tension of the cable 4 greatly fluctuating due to the swing of the hull 1, the jib 9 of the observation device 3 is passively raised. Since the operation is merely made to follow, and the moment of inertia relating to the raising operation of the jib 9 is large, the response of the observation device 3 to the actual fluctuation in the tension of the cable 4 tends to be delayed, and the excessive load applied to the cable 4 There is a possibility that the load cannot be reliably avoided.

In addition, in the passive operation mode using the conventional overload prevention device as described above, it is unavoidable that the cable 4 is subjected to forced vibrations affected by waves, and Cable 4 long down to the sea floor
At the resonance point existing in the middle of the cable, a twisting phenomenon called a kink in the art as shown in FIG. 6 occurs, and there is a concern that the cable 4 receives a local stress concentration at the location where the kink occurs and is cut. Still remained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a suspension device capable of reliably avoiding an overload applied to a cable or other cable and preventing the cable from being cut. An object of the present invention is to provide an overload prevention method and apparatus.

[0013]

SUMMARY OF THE INVENTION According to the present invention, there is provided a suspension system which is installed on a deck, protrudes to the side of a hull, and suspends a suspended object from the tip of the hull through a cable-like body in the sea. An overload prevention method for a suspension device, comprising raising and lowering the suspension device such that a distance between a feed-out position of a cord-like body and a virtual reference sea surface is kept constant in response to a swing of a hull. Is controlled.

Thus, even if the hull sways due to the waves, the lifting operation of the suspension device is actively controlled in response to the sway, and the tip of the suspension device at the tip of the suspension device is actively controlled. Since the distance between the unwinding position of the cord and the virtual reference sea level is always kept constant, the coordinate point of the unwinding position of the cord with respect to the earth axis becomes almost immovable,
Large tension fluctuations and forced vibrations do not occur in a cable such as a cable that suspends and supports a suspended object from the tip of the suspension device, and overload on the cable is reliably avoided. Become.

When the method of the present invention is specifically carried out, for example, an accelerometer which is attached to an appropriate position on the hull and detects vertical acceleration of the attached position and a rolling angle of the hull are detected. The goniometer and a hydraulic system that calculates the heaving amount of the hull from the detected values of the goniometer and the accelerometer and controls the hydraulic system responsible for raising and lowering the suspension device based on the heaving amount and the rolling angle by the goniometer. An overload prevention device for a suspension device may be employed, comprising a control device for maintaining a constant distance between the line feeding position and the virtual reference sea surface.

Thus, when such a device is adopted, the acceleration of vertical movement at an appropriate position of the hull is detected by the accelerometer, and the rolling angle of the hull is detected by the goniometer. Since the heaving amount of the hull is calculated by the control device based on the acceleration and the rolling angle obtained, the heaving amount at the extension position of the cord-like body at the tip of the suspension device is calculated based on the heaving amount and the rolling angle. By controlling the hydraulic system responsible for raising and lowering the suspension so as to offset the heaving amount at the extension position of the cord, the distance between the extension position of the cord and the virtual reference sea surface is kept constant. Will be done.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an embodiment of the present invention. The same reference numerals as in FIGS. 4 to 6 denote the same parts.

As shown in FIGS. 1 and 2, substantially in the same manner as the above-described observation device 3 shown in FIG. 4, it is installed on the deck 2 and projects to the side of the hull 1 and a cable 4 (cord-like body) extends from the tip thereof.
With respect to the observation device 3 which performs the work by suspending the observation equipment (suspended object) under the sea via the sea, in the present embodiment, the acceleration of the vertical movement of the hull 1 is changed one by one on the port side and the starboard side of the hull 1. Accelerometers 21 and 22 for detecting are provided, respectively, and a goniometer 23 for detecting a rolling angle of the hull 1 is provided at an intermediate position in the width direction of the hull 1 between the two accelerometers 21 and 22. The detection signals from the goniometer 23 and the accelerometers 21 and 22 are transmitted to the jib 9 (main boom 7).
Control device 24 for controlling the hydraulic system responsible for the lifting operation of the vehicle
To be entered.

The raising hydraulic cylinder 10 for raising and lowering the jib 9 is a variable displacement pump 25 capable of bidirectionally supplying hydraulic oil 16 between the extension oil chamber and the shortening oil chamber.
The variable displacement pump 25 is controlled by a control signal 26 from the control device 24, so that the hydraulic oil 16 can be appropriately connected between the expansion side oil chamber and the shortening side oil chamber.
Is moved so that the expansion / contraction operation of the hydraulic cylinder for elevating 10 can be accurately controlled.

Strictly speaking, when the hydraulic oil 16 moves back and forth between the extension-side oil chamber and the contraction-side oil chamber, the amount of the hydraulic oil 16 moving from the contraction-side oil chamber to the extension-side oil chamber is reduced by a rod. However, in this regard, an oil amount adjusting mechanism (not shown) may be attached to the hydraulic system for adjustment.

The controller 24 receives an operation command from the driver and outputs a control signal 26 to the variable displacement pump 25, thereby controlling the expansion / contraction operation of the hydraulic cylinder 10 for raising and lowering the driver. Jib 9 at the elevation angle as instructed
The basic control logic is to activate the jib. However, during the automatic operation when suspending the observation equipment under the sea and performing the work, the elevation operation of the jib 9 is automatically performed by the control logic as described in detail below. Control.

That is, the control flow of the control device 24 during automatic operation is as shown in FIG. 3. First, in the first step S1 after the automatic operation is started, the elevation angle of the jib 9 and the main boom 7 are determined. , An initial specification value relating to the attitude of the observation device 3 such as the inclination angle of the deck 2 (rolling angle of the hull 1) by the goniometer 23 is measured.

Incidentally, the initial specifications other than the inclination angle of the deck 2 surface by the goniometer 23 are naturally measured conventionally in controlling the attitude of the observation device 3, and the jib 9.
A value measured by installing an absolute encoder or the like at the tilting position of the main boom 7 or the auxiliary boom 8 (see FIG. 4) is input to the control device 24 as a detection signal.

In the next step S2, the initial posture of the observation device 3 is recognized based on the initial specification values measured in step S1, and the tip of the jib 9 in the recognized initial posture of the observation device 3 is recognized. The distance A ₀ between the unwinding position of the cable 4 and the virtual reference sea level L in FIG.
Is calculated.

Here, the virtual reference sea level L refers to a fixed sea level temporarily determined with respect to the earth axis, regardless of the sea surface where the actual waves are generated, and the distance A ₀ based on this is assumed. Are also tentatively determined to be used as indices for subsequent control.

From step S3, the substantial control is repeatedly performed in a very minute time unit.
More specifically, in step S3, the current specification value is measured again, and the acceleration of vertical movement of the hull 1 is measured by the two accelerometers 21 and 22, and the next step S4
Then, the heaving amount H and the rolling angle S of the hull 1 are calculated.

That is, if the accelerations of the vertical movement indicated by the arrow X in FIG. 2 at the port side and the starboard side are measured by the two accelerometers 21 and 22, the respective accelerations are integrated twice to obtain the vertical direction per unit time. it is possible to determine the amount of displacement of the heaving amount H _p, as H _s, these heaving amount H _p, with obtaining the heaving amount H in the width direction intermediate position of the hull 1 based on H _s, heaving amount H _p, H _The rolling displacement indicated by arrow Y in FIG. 2 is obtained based on _s, and the rolling displacement is added to the latest updated rolling angle in the past to calculate the rolling angle S.

Next, in step S5, the first correction coefficient α _n is calculated by dividing the rolling angle S calculated in step S4 by the actually measured rolling angle θ _dn by the goniometer 23.

That is, the first correction coefficient α _n is obtained by comparing the rolling angle S calculated based on the accelerations of the two accelerometers 21 and 22 with the actually measured rolling angle θ _{dn of the goniometer} 23. The purpose of the present invention is to examine the reliability of acceleration measured by the accelerometers 21 and 22, add a correction corresponding to the reliability to the heaving amount H, and bring the heaving amount H closer to a true value.

In the next step S6, the current heaving amount H calculated in step S4 is compared with the moving average value of the time series data of the heaving amount H calculated in the past to make a second correction. The coefficient β _n is calculated.

That is, the second correction coefficient β _n is used to extract the overall trend by removing accidental fluctuations and periodic fluctuations from the past time-series data to extract the overall heaving amount H in the past.
The purpose is to bring the heaving amount H closer to the true value by taking the moving average value of the time series data into consideration.

Then, in step S7, the heave amount H obtained in step S4 is multiplied by the first correction coefficient α _n obtained in step S5 and the second correction coefficient β _n obtained in step S6. true value h _n of heaving amount is to be calculated by.

Furthermore, in the next step S8, heaving amount in the heaving of the true value h _n, based on the rolling angle theta _dn of actual measured in step S3, the tip position of the jib 9 of the observation apparatus 3 H ′ is calculated,
Distance A _n between the mean sea level L of the virtual and extended position of the cable 4 is calculated at the tip of the jib 9 displaced.

[0035] At the next step S9, the jib 9 so as to return the distance A _n between the mean sea level L of the virtual and extended position of the cable 4 which is calculated in step S8 the initial distance A ₀ of elevation Control data for the operation is calculated, and in the next step S10, the control device 24 sends the variable displacement pump 2
The control signal 26 is output toward 5, and the appropriate raising operation of the jib 9 is performed.

The control procedure from step S3 to step S10 is repeatedly performed unless the automatic operation stop button operation is confirmed in step S11, so that the automatic operation is continued.

By adopting the overload prevention device as described above and performing automatic operation by the control device 24, even if the hull 1 oscillates due to waves, it can cope with the oscillation. As a result, the elevation operation of the observation device 3 is actively controlled, and the distance A ₀ between the unwinding position of the cable 4 at the tip of the observation device 3 and the virtual reference sea level L is always kept constant. The coordinate point of the extension position of the cable 4 with respect to the earth axis becomes almost immovable, and large tension fluctuation and forced vibration do not occur in the cable 4 that suspends and supports the observation device from the tip of the observation device 3. An overload on the cable 4 is reliably avoided.

Therefore, according to the above-described embodiment, the cable which suspends and supports the observation equipment from the end of the jib 9 of the observation device 3 by setting the coordinate point of the feeding position of the cable 4 with respect to the earth axis to be almost fixed. 4 can avoid large tension fluctuations and forced vibrations before they occur.
An overload applied to the cable 4 can be reliably avoided, and the cable 4 can be prevented from being cut.

It should be noted that the method and apparatus for preventing overload of the suspension device of the present invention are not limited to the above-described embodiment, and the suspension device may be configured to perform observation by suspending observation equipment under the sea. In addition to the above observation equipment, it may be a jib crane for ships that is responsible for offshore loading and unloading work under the sea or on the sea floor.Also, an accelerometer can be installed at the tip of the jib, It is also possible to further improve the accuracy by installing a goniometer on the cable, and that the cord-like body may be a rope other than the cable, etc. Of course, various changes can be made without departing from the scope.

[0040]

According to the method and apparatus for preventing an overload of a suspension according to the present invention, the coordinate point of the feeding position of the cord-like body with respect to the earth axis is almost fixed, and the tip of the suspension is controlled. Large tension fluctuations and forced vibrations can be prevented from occurring in a cable or other cable that suspends and suspends a suspended object, so that an overload on the cable can be reliably avoided. Thus, an excellent effect that the cutting of the cord-like body can be prevented can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment for implementing the present invention.

FIG. 2 is an explanatory diagram of a swing of a hull in an embodiment of the present invention.

FIG. 3 is a block diagram illustrating a control flow relating to automatic driving in the control device of FIG. 1;

FIG. 4 is a schematic view showing an example of a general suspension device.

FIG. 5 is a schematic view showing a conventional example.

FIG. 6 is a diagram showing a state in which a twisting phenomenon has occurred in the cable of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hull 2 Deck 3 Observation device (suspension device) 4 Cable (cord-like body) 9 Jib 10 Hydraulic cylinder for elevating 21 Accelerometer 22 Accelerometer 23 Angle meter 24 Controller 25 Variable capacity pump (hydraulic system)

Claims (2)

[Claims] 1. A method for preventing an overload of a suspension device, which is installed on a deck, protrudes to the side of a hull, and suspends a suspended object from the tip of the hull in a sea through a cord-like body. The lifting operation of the suspension device is controlled such that the distance between the feeding position of the cord-like body and the virtual reference sea surface is kept constant in response to the swing of the hull. Method of preventing overload of suspension equipment. 2. An overload prevention device for a suspension device which is installed on a deck, projects to the side of a hull, and hangs a suspended object from the tip of the hull into the sea via a cord-like body. An accelerometer attached to an appropriate position on the hull to detect vertical acceleration at the attachment position; an angle meter for detecting a rolling angle of the hull; and a hull based on the detected values of the angle meter and the accelerometer. Calculate the heaving amount and control the hydraulic system responsible for the elevating operation of the suspension device based on the heaving amount and the rolling angle by the goniometer to determine the distance between the extension position of the cord-like body and the virtual reference sea surface. An overload prevention device for a suspension device, comprising: a control device for keeping the suspension constant.