JPS62205891A - Automatic position-keeping device for moored floating body - Google Patents

Abstract

PURPOSE:To automate the designated-position-keeping-work, by calculating the cable drawing-out/rewinding length, which is necessary to put a floating body back to the designated position, and using the signals from a cable length meter, thereby controlling the start/stop operation of winch. CONSTITUTION:Based on the floating body position, which is continuously measured by a floating body position measuring device 1, the coordinates of the designated position of the floating body, which is manually set by using a position setting circuit, and the tension of each ship-mooring cable, an arithmetic circuit 4 calculates the cable drawing-out/rewinding length of each ship mooring cable, which is necessary to put the position of the floating body back to the designated position. Next, after inputting the signal for the cable drawing- out/rewinding length which is detected by a cable length meter, a control signal output circuit 6 gives the start/stop instruction to a winch start/stop control device 7, in order to perform the drawing-out or rewinding of the cable to the length as obtained in the above. With this contrivance, both automation and accuracy-improvement in the designated-mooring-position-keeing-work can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic position holding device for a moored floating body that controls the cable payout and retraction of a mooring winch of a floating body moored to a quay or a sea ring by a cable.

[Conventional technology]

For example, the work to maintain a ship's position at a fixed position when moored at a quay has traditionally been carried out based on the experience of the crew, but has not been carried out due to disturbances such as tidal currents, wind, etc., or changes in the ship's stagnation due to the progress of unloading or cargo. When the position of the ship deviates from a predetermined position, the crew operates the mooring winch each time to adjust the position of the ship by letting out and reeling in the mooring line.

There is an auto-tension winch as a device that automatically adjusts the mooring line, but this is a device that controls the tension so that the tension applied to the mooring line is below a certain value. Furthermore, there is currently no device in practical use that has the function of automatically maintaining the ship's position in a fixed position.

However, such a device has the following drawbacks.

(1) Every time the predetermined mooring position shifts due to disturbances or changes in the ship's stasis, the crew must operate the winch to correct the ship position, which is troublesome and requires manpower.

(2) Corrections are made based on the crew's intuition based on their experience, so
It cannot be said that the mooring position is necessarily corrected to the specified mooring position.

[Problem that the invention seeks to solve]

The present invention was proposed in view of these circumstances, and
An object of the present invention is to provide an automatic position holding device for a moored floating body that automates the work of holding a predetermined mooring position and improves accuracy.

[Means for solving problems]

To this end, the present invention provides an automatic position holding device for a moored floating body that performs mooring winch cable payout and winding control for a floating body moored at a plurality of fixed points by a plurality of ropes, and a floating body that continuously measures the position of the floating body. a position measuring device, a position setting circuit capable of setting coordinates of a predetermined position with respect to the fixed point of the floating body, and determining the floating body position based on the floating body position detected from the floating body position measuring device and the position setting circuit. An arithmetic circuit that calculates the length of the rope required to return the rope to the predetermined position, a rope length meter that detects the length of the rope, and only the length of the rope calculated by the arithmetic circuit. The mooring winch is characterized by comprising a control signal output circuit that outputs a start/stop instruction to the mooring winch in order to let out or wind in the cable.

[Effect]

With the above-described configuration, it is possible to obtain an automatic position holding device for a moored floating body that automates the work of holding a predetermined mooring position and improves accuracy.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing its circuit configuration, and FIG. 2 is a perspective view showing a coordinate system regarding the hull position of a moored ship.

In Figure 1, l is a ship position measuring device that continuously measures the ship's position, 2 is a rope tension meter that measures the tension of each mooring line (hereinafter referred to as a rope), and 3 is a cable tension meter that measures the tension of each mooring line (hereinafter referred to as a rope), and 3 is a ship position measuring device that continuously measures the ship's position. A manual setting circuit 4 sets the result of measuring the coordinates of the bit by a position measuring device, and 4 is a manual setting circuit that uses the ship position and cable tension detected from the ship position measuring device 1 and the cable tension meter 2 to detect a case where the ship position deviates from a predetermined position. 5 is an arithmetic circuit that calculates the amount of cable reeling and reeling required to return the ship to a predetermined position from the amount of change in the ship's position; 5 is a cable length meter that measures the length of each rope retracting; 6 is the arithmetic circuit 4; 7 is a winch start/stop control device. In the hull of the moored ship, 0 is the origin of the coordinates, and the center of gravity of the ship at a predetermined position of the hull 8 is defined as the origin O.

X is the X coordinate axis taken in the length direction of the hull 8, Y is the Y coordinate axis taken in the width direction of the hull 8, Z is the Z coordinate axis in the direction perpendicular to the X-Y plane, and θ is the rotation around the ship's center of gravity O. This is the horizontal rotation angle with clockwise rotation as positive.

In such a device, first, the current value of the ship position z, ? input from the ship position measuring device 1 is input. , y, and θ, the calculation circuit 4 calculates the winding length of the rope to return the ship to its original predetermined position by the following method.

That is, some external force acts on the hull 8, which was initially stationary at the original predetermined position, and the hull position changes, and the external force and the tension of the rope are statically balanced, and the hull 8 is moved to the new position. Consider the case where it stops.

In this case, assuming that each external force is constant before and after the change in external force, the following static balance condition is established.

However, the balance condition regarding the moment of force around the ship's center of gravity is excluded.

Here, T, i: The magnitude of the tension in the i-th cable before the change in external force Ti: The magnitude of the tension in the i-th cable after the change in external force FOZ: The two-directional component p of the external force before the change in external force, : What about the external force before the external force change? Directional component F2: Two-directional component of external force after change in external force αoxi: Direction cosine of the i-th cable before change in external force Direction cosine of the second cable 2-component α Direction cosine of the i-th cable after change in external force? Component ゛N: Number of mooring lines i: Cable number corresponding one-to-one to each line Based on the cable payout and winding length calculated by the above method, the calculation circuit 4 instructs the control signal output circuit 6 to start winch control. Upon outputting the instruction signal, the control signal output circuit 6 immediately outputs a winch operation start signal to the winch start/stop control device 7.

Then, the control signal output circuit 6 inputs the length of the rope when it is let out and wound in from the cable length meter 5, and compares it with the length of the rope when it is let out and wound in as input from the arithmetic circuit 4. When the two values match, the winch starts and stops. A winch stop signal is output to the control device 7.

In addition, the calculation circuit 4 compares the current ship position input from the ship position measuring device 1 with the coordinates of the original predetermined position, and if the difference between these values falls within a certain range, the ship position is considered to have returned to the original predetermined position. If the difference is within a certain range, the arithmetic circuit 4 performs the above calculation again, and the winching operation is performed.

In this case, in order for the external force after the change and the cable tension Ti'' to be statically balanced at the original predetermined position, the following equation must be established, and the cable tension Ti4+ is equal to the ship position at the original predetermined position. This is the amount of cable tension required to hold the cable.

Normally, the amount of change in the ship's position is considered to be sufficiently small compared to the cable length, so it can be regarded as 'r7='r7... (
4).

On the other hand, assuming that the elongation characteristics of the cable follow Hooke's law, the cable tension T is expressed as follows.

T = To+K (1-1o-8)・・・・・・・・・
...(5) Here, the initial tension of the F6 m cable is: Spring constant of the cable l: Cable length at the current ship position 1, : Cable length S when the ship is at the original predetermined position: Therefore, from equations (4) and (5), before and after the change in external force, T, 10K (J-J, ) = T, -KS-...
...(6) From equation (6), t:, s = -(1-to) is found.

In other words, if the cable is let out and reeled in by the difference in cable length between the current ship position and the original predetermined position, the resultant force of the horizontal component of the tension of each cable and the horizontal component of the external force will be Static balance is achieved and the hull 8 returns to its original predetermined position.

Note that the moment of force around the two axes is not taken into account during the above calculation, so after the cable is let out and wound in,
Although some rotational displacement occurs, this is considered to be within a negligible range.

In addition, the cable length is calculated by the following method based on the ship position input from the ship position measurement device 1. In other words, the cable length is the straight line distance between the mooring winch and the fairlead, and the distance between the fairlead and the bit. Since the straight line distance between the mooring winch and the fairlead is constant, the distance between the fairlead and the davit is calculated as the sum of the straight line distance.

The position coordinates of the fairlead in the coordinate system shown in Fig. 2 are the coordinates Z + of the ship's center of gravity input from the ship position measuring device l.
It can be calculated from the three-dimensional position coordinates of the fairlead on the coordinate system fixed to the hull 8 using 1 + 2 + rotation angle θ.

In addition, the coordinates of the pit position are measured using an appropriate position measuring device, for example, a triangulation method as a simple method, when the hull 8 is in the original predetermined position, and manually set in the manual setting circuit 3, and then set in the fair position. The distance between the leader and the bit is calculated from each three-dimensional coordinate position using the Pythagorean theorem.

Based on the current ship position detected by the ship position measuring device 1, the arithmetic circuit 4 checks whether the ship position has deviated from the original predetermined position.If the ship position has deviated from the predetermined position, the ship position The calculation circuit 4 calculates the length of the rope required to return the cable to its original predetermined position, and the calculation circuit 4 also uses signals from the cable length dynamometer 2 to ensure the safety of the cable. Possible 0 When the control signal output circuit 6 operates each winch so as to let out or reel in the rope by the length calculated by the arithmetic circuit 4, the length of the rope to be let out or reeled in is determined for each rope. The winch is stopped in operation by an output signal from the control signal output circuit 6 at the time when the length detected by the cable length meter 5 provided in the cable matches the length of the payout or retraction calculated by the arithmetic circuit 4.

The ship's position is detected by the ship's position measuring device 1. For example, if the external force changes after the calculation circuit 4 calculates the length of the rope to be reeled in, the ship's position does not return to its original predetermined position even after the winch operation is completed. When the arithmetic circuit 4 determines that, the arithmetic circuit 4 calculates the necessary length of the cable to be let out or rolled in again,
The same process is repeated thereafter.

According to such a device, when a moored floating body is moored at a fixed point using a mooring line, and its position deviates from its original predetermined position, the length of the cable can be compared with the length when the mooring line is at its original predetermined position. By adding a function to the mooring winch that calculates the difference between the cable length at the shifted position and automatically feeds out and retracts the cable by this difference, the position can be automatically maintained at the original predetermined position. Therefore, the following effects can be achieved.

(1) Since the work of maintaining the position of the moored floating body can be automated, it is possible to save the number of crew members.

(2) Since the work of maintaining the position of the moored floating body can be automated, the position holding accuracy is increased and the safety of the moored floating body is improved.

〔Effect of the invention〕

In short, according to the present invention, in an automatic position holding device for a moored floating body that performs mooring winch cable payout and winding control of a floating body moored at a plurality of fixed points by a plurality of ropes, the floating body continuously measures the position of the floating body. a position measuring device, a position setting circuit capable of setting the coordinates of a predetermined position regarding the fixed point of the floating body, and a position of the floating body based on the floating body position detected from the floating body position measuring device and the position setting circuit. an arithmetic circuit that calculates the length of the rope required to be retracted and retracted to return the rope to the predetermined position; a rope length meter that detects the length of the rope that is retracted and retracted; A moored floating object is provided with a control signal output circuit that outputs start/stop instructions to the mooring winch in order to pay out or reel in the mooring winch, thereby automating the work of maintaining a predetermined mooring position and improving accuracy. Therefore, the present invention is extremely useful industrially.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is a perspective view showing a coordinate system regarding the hull position of a moored ship. 1. Ship position measurement device, 2. Force tension meter, 3. Manual setting circuit, 4. Arithmetic circuit, 5. Cable length meter, 6. Control signal output circuit, 7. Winch start/stop control device, 8 ...hull, 0...origin, X...X coordinate axis, Y...X coordinate axis, 2...
2 coordinate axes, θ...Horizontal rotation angle, Sub-Agent Patent Attorney Masaru Tsukamoto Figure 1 Figure 2

Claims (1)

[Claims] In an automatic position holding device for a moored floating body that performs mooring winch cable payout and winding control for a floating body moored at a plurality of fixed points by a plurality of ropes, a floating body position that continuously measures the position of the floating body. a measuring device, a position setting circuit capable of setting coordinates of a predetermined position with respect to the fixed point of the floating body, and determining the floating body position based on the floating body position detected from the floating body position measuring device and the position setting circuit. An arithmetic circuit that calculates the length of the rope required to return the rope to the predetermined position, a rope length meter that detects the length of the rope that is unrolled and retracted, and only the length of the rope calculated by the arithmetic circuit. An automatic position holding device for a moored floating body, comprising a control signal output circuit that outputs a start/stop instruction to the mooring winch in order to let out or wind in the cable.