JPS624279B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position control device for a work platform equipped with a plurality of sets of mooring winch mechanisms.

Incidentally, recent marine civil engineering work requires improvements in work precision and work efficiency that were previously unimaginable. For example, before constructing an offshore structure, work is carried out to solidify the foundation of the structure, and before ocean reclamation, work is carried out to improve the soft ground on the ocean floor.

This improvement work is normally carried out using a work slip.

The improvement work using this work platform involves lowering an agitator consisting of a large number of impellers into the seabed soil, rotating the impeller to agitate the seabed soil, and after reaching the improvement depth of the ground, the agitator is lowered into the seabed soil. Cement is injected while pulling up the seabed, and the rotating impeller of the stirrer thoroughly mixes the seabed sediment and cement, solidifying the seabed ground and improving soft ground.

Therefore, during ground improvement work using an agitator equipped with a working platform, it is not allowed to change the position of the working platform. For example, if the working platform changes its position significantly due to wind, waves, currents, etc. , which could damage the agitator that is being lowered into the seabed soil.

Therefore, the work platform is moored with a large number of wires to prevent its position from changing due to disturbance forces such as wind and waves.

In addition, the wire is fixed to the seabed by an anchor,
In order to counter the disturbance force applied to the work platform, a strong tension is applied to the wire by a winch mechanism on the work platform.

Furthermore, the ground area that can be improved by one lifting and lowering of the stirrer is only a ^few square meters, and in order to improve the adjacent seabed ground, the work platform must be moved and the area must be 3 to 5 cm above the improved seabed ground. It is necessary to lower the agitators so that they overlap and begin the next ground improvement work.

Therefore, the position of the work platform must be accurately measured to an accuracy of 1 cm or less.

In addition, in order to prevent undue force from acting on the stirrer lowered into the seabed soil during ground improvement work, the positional fluctuation of the work platform must be within ±10 cm in waters several tens of meters deep. It won't happen.

In this way, recent offshore civil engineering work requires precision work that was previously unimaginable, and at the same time, one seabed ground improvement work takes 1 to 2 hours, so it is necessary to improve vast areas of seabed. Improving work efficiency has become an urgent issue.

FIG. 1 is a plan view showing how the work boat 1 is moored with a wire 5 to hold it in a fixed position and how the position of the work boat 1 is detected. It is an elevational view showing the state of the improvement work.

The work platform houses an agitator 3 in a tower 2, and when working to improve the submarine ground 4,
As shown in FIG. 2, the agitator 3 is lowered into the seabed 4.

Further, the work platform 1 is moored by a large number of wires 5 (eight wires are shown in FIG. 1), and each wire 5 has one end fixed to the seabed by an anchor 6. Further, a large tension is applied to each wire 5 by a winch 7, and a large tension is applied to each wire 5.
The work platform 1 is designed not to move due to disturbance forces such as wind, waves, and currents that are applied to the work platform 1.

By the way, the work platform 1 has 3 placed on it.
Optical distance meter (or radio distance meter) 8, 9, 1
The distance between the two reference points established on the land 11 by 0 and the optical distance meter 8, 9, 10
By measuring l ₁ , l ₂ and l ₃ , the position and orientation of the working platform 1 can be determined.

That is, the light wave distance meters 8 and 9 measure the distances l ₁ and l ₂ from the reference point, respectively, and the light wave distance meter 10 measures the distance l ₃ from the reference point, but the principle of these light wave distance meters will be briefly explained. To explain this, first, light is modulated into waves of high and low intensity, and these light waves are emitted from a light wave rangefinder and made to travel back and forth between measurement distances. Reflecting mirrors 12, 13, and 14 are installed at distance measurement points so that the light emitted from the light wave distance meter can travel back and forth between measurement distances.

In this way, the light wave distance meter can determine the measured distance from the phase relationship between the emitted light and the incident light reflected by the reflecting mirror.

Note that the light wave distance meter has already been commercialized, and further explanation of its principle will be omitted. Further, a reflector 12 for the lightwave rangefinder 8 and a reflector 13 for the lightwave rangefinder 9 are installed at the reference point.
At the reference point, there is a reflector 1 for the optical distance meter 10.
4 is installed.

By the way, to explain the calculation method for determining the position and direction of the work platform 1 by measuring the distances l ₁ , l ₂ , and l _{3 ,} first, as shown in Fig. 3, a straight line connecting the reference point of the land 11 and The y-axis is perpendicular to the x-axis in a horizontal plane, and the origin of these x- and y-axes is the reference point.

It is also assumed that the optical distance meters 8, 9, and 10 are on a straight line, and are located at points A, B, and C in FIG. 3, respectively.

Therefore, the line segment has a length l ₁ , the line segment has a length l ₂ , and the line segment has a length l ₃ .

Furthermore, the position of the work platform 1 is set to the center P of the agitator 3.
Let it be represented by a point.

Here, before finding the position of the work platform 1,
Reference point, distance L ₁ between light wave distance meter 10 and P
Distance L ₂ between points, distance between light wave distance meters 8 and 10
L ₃ , distance L ₄ between light wave distance meters 9 and 10 and straight line
Measure the angle between ABC and straight line PC.

In order to find the coordinates (X, Y) of the position P of the work platform 1 using the x, y coordinates in Figure 3, draw a dotted line parallel to the y-axis from point P, and draw a dotted line parallel to the x-axis from point C. Draw a dotted line and let the intersection of these two dotted lines be point P'.

Now let ∠C = α, ∠BC = γ, and the length of the line segment is l ₄ , then the position coordinates of point P (X,
Y) is determined by the following formula.

Here, we are using the fact that ∠P′CA = α−γ.

Next, find the unknowns l ₄ , α, and γ in equation (1).

In this case, apply the law of cosines to triangle AC.

L ² ₃ +l ² ₄ -l ² ₁ =2L ₃ l ₄ cos γ (2) Also, apply the cosine theorem to triangle BC.

L ² ₄ + l ² ₄ - l ² ₂ = 2L ₄ l ₄ cos γ ......(3) From equations (2) and (3), (L ² ₃ + l ² ₄ - ^{l 2} ₁ )/L ₃ = (L ² ₄ + l ² ₄ - l ² ₂ )/L ₄ = 2 l ₄ cos γ
………(4) Here, L ₃ ≠ 0 From this formula (4), l ₄ = √ _{3 4} + ( ₃ ² ₂ − ₄ ² ₁ ) ( ₃ − ₄
)......(5) Next, by applying the cosine theorem to triangle CI, α=cos ^-1 {(l ² ₄ + L ² ₁ - l ² ₃ )/(2l ₄ L ₁ )}
......(6) Also, from equation (2), γ=cos ^-1 {(L ² ₃ + l ² ₄ - l ² ₁ )/(2L ₃ l ₄ )}
......(7) Since the unknowns l ₄ , α, and γ have been obtained from equations (5), (6), and (7), respectively, the position of the work platform 1 can be found from equation (1).

Further, if the azimuth angle Ψ of the work platform 1 is the angle Ψ formed by the straight line ABC and the x-axis as shown in FIG. 3, the azimuth angle Ψ can be found from the following equation.

Ψ=α−γ ………(8) In this way, three light wave distance meters 8, 9, 10
3 between the two reference points of and land 11 and
By measuring the distances l ₁ , l ₂ , l ₃ respectively, the position coordinates X, Y and azimuth Ψ of the work platform 1 are determined.
can be found.

The accuracy of a light wave distance meter (or radio wave distance meter) is ±(5 mm + 10 ^-5 D) [D: measurement distance (mm)], which is sufficient for normal marine civil engineering work.

By the way, since the worker must constantly hold the work platform 1 at a predetermined position and orientation, the worker must operate multiple winches 7 simultaneously while monitoring the position coordinates X, Y and azimuth Ψ of the work platform 1. However, the wire 5 must be continuously fed out and drawn in.

Now, in the case where hydraulic power is used to drive the winch, the control device for one of the multiple winches is shown in Figure 4.
The winch control device shown in FIG. 4 is independent for each winch.

Now, when the operator operates the control motor 02 by operating the inclination angle of the winch valve lever 01 and changes the opening degree of the winch valve 03, the winch valve 03 will function as a flow control valve to control the oil amount. At the same time, the direction of oil flow is changed.

By the way, when the winch valve 03 forms the flow path shown by 〓〓, the oil from the pump 04, which is controlled to a predetermined oil amount by the winch valve 03, enters the piping path A and passes through the first reverse valve 05. The motor then enters the hydraulic motor 06 and applies torque to the hydraulic motor 06.

The torque from the hydraulic motor 06 is increased by the reduction gear 07 and transmitted to the winch drum 08, which rotates the winch drum 08 at a predetermined rotational speed against the reverse torque received from the wire 09. Perform renormalization.

Note that the oil that has passed through the hydraulic motor 06 is transferred to piping path B.
After passing through the winch valve 03, the tank 010
Return to

Next, when the winch valve 03 forms the flow path shown by In the case of , the opposite torque is applied, that is, the torque that tries to unwind the wire.

Since the hydraulic motor 06 is constantly subjected to torque that tries to feed out the wire via the reduction gear 07 due to wire tension, the hydraulic motor 06
rotates rapidly and tries to pay out the wire.

Such a rapid increase in rotation of the hydraulic motor 06 causes a rapid pressure drop in the pipe line B, and there is a risk of cavitation, so rapid rotation is prevented when the hydraulic motor 06 performs a wire feeding operation. A counterbalance valve 011 and a throttle 012 are provided for this purpose.

The opening degree of the counter drance valve 011 is changed by a throttle 012 that detects the pressure in the pipe line B.

Note that when the pressure in the pipeline B increases, the counterbalance valve 011 is opened, and when the pressure in the pipeline B decreases, the counterbalance valve 011 is closed. Therefore, when the winch valve 03 sends oil to the pipe line B and the hydraulic motor 06 pays out the wire at a moderate rotational speed, the pressure in the pipe line B does not drop rapidly, so the oil is sent to the pipe line B. The pressure is maintained, the counterbalance valve 011 is opened by the throttle 012, and the oil that has passed through the hydraulic motor 06 returns to the tank 010 through the counterbalance valve 011.

At this time, oil cannot pass through the first check valve 05.

However, as the rotational speed of the hydraulic motor 06 rapidly increases, the pressure in the pipe line B rapidly decreases.
There is a risk of cavitation occurring, but if the pressure in the pipe line B drops at this time, the throttle 012 is
As a result, the counterbalance valve 011 is closed,
As a result, the pressure in the piping path C of the hydraulic motor 06 increases, a brake torque acts on the hydraulic motor 06, and the increase in rotation of the hydraulic motor 06 is suppressed.

In this way, the counterbalance valve 011 plays the role of applying brake torque to the hydraulic motor 06 to feed out the wire at an appropriate speed even when the wire is fed out.

After the wire operation is completed, the opening degree of the winch valve 03 becomes a neutral state by operating the winch valve lever 01, and at an opening degree near the neutral state, the amount of oil from the winch valve 03 becomes zero.

Note that FIG. 5 is a graph showing the relationship between the opening degree of the winch valve 03 and the oil amount.

However, since oil generally leaks from the hydraulic motor 06, the piping line C of the hydraulic motor 06
pressure drops and there is a risk that the wire will be unwound by itself, which causes the line C of the hydraulic motor 06 to
It is necessary to constantly compensate for oil leakage. For this purpose, oil is replenished from a low discharge constant pressure pump 013 through a second check valve 014.

Furthermore, the relief valve 015 plays a role of releasing the oil so that the pressure in the piping path C of the hydraulic motor 06 does not become excessively high due to this replenished oil. Generally, the winch drum is equipped with a mechanical brake (not shown) to prevent the wire from being fed out.

As explained above, the work platform 1 used for conventional marine civil engineering work usually has the following structure, as shown in FIG.
Equipped with 6 to 8 wires, one worker monitors the position and azimuth of the work platform 1, which is subject to disturbances such as wind, waves, and currents. Since the levers of 6 to 8 winches are operated simultaneously, it requires considerable skill to constantly maintain the work platform 1 at a fixed position and azimuth. The problem is that the position and azimuth angle must be maintained by repeatedly correcting the operation, which requires a large amount of labor even for unskilled personnel, deteriorating work ability and reducing safety. There is a point.

Therefore, disturbance forces (wind, wind,
The proportional (P) +
An automatic control means has also been considered in which the winch is subjected to feedback control using a differential (D) element to control the tension of the wire.

However, with such automatic control means,
It is necessary to detect disturbance force, but it is extremely difficult to detect such disturbance force, and the detected value contains a large error, so it is difficult to perform position holding control of work platform 1 stably and with high accuracy. It is.

The present invention aims to solve these problems and requires the operation of a large number of winches in order to constantly maintain the position and orientation of a work platform moored by a large number of wires at predetermined values. Automation means that once the worker sets the position and azimuth of the work platform, numerous winches are automatically operated according to the optimal operating procedure, and the desired position and azimuth are set. To provide a position control device for a work platform that can stably maintain the work platform with high precision and reduce the labor burden on workers.

For this reason, the work platform position control device of the present invention includes a winch valve whose opening degree is adjusted by a control motor, a fluid pressure motor rotationally driven by fluid supplied through the winch valve, and a wire. A work platform equipped with a plurality of mooring winch mechanisms each having a winch drum wound around the drum and rotationally driven by the fluid pressure motor, and a relief valve for adjusting the high pressure side pressure of the fluid pressure motor. a position setting device that outputs set position coordinate signals x _s , y _s of the work boat in a spatially fixed coordinate system, an azimuth setter that outputs a set orientation signal Ψ _s of the work boat, and a position coordinate of the work boat. It is equipped with a position/direction detector that outputs signals x, y and a direction signal Ψ, and an output signal x from the position setting device.
a first subtractor that inputs _s and an output signal x from the position/azimuth detector, and a second subtractor that inputs an output signal y _s from the position setter and an output signal y from the position/azimuth detector. a third subtractor inputting the output signal Ψ _s from the azimuth setter and the output signal Ψ from the position/azimuth detector; A position error converter that inputs the output signal and the output signal Ψ _s from the azimuth setting device and outputs a position deviation signal △x ₀ in a set azimuth direction and a position deviation signal △y ₀ in a direction perpendicular to the set azimuth. and the position deviation signal △x ₀ from the same position deviation converter
A first PID controller or a first PD controller that inputs the position error signal Δy 0 from the position error converter, and a second PID controller or second PD that inputs the position error signal Δy ₀ from the position error converter.
controller, and a third PID controller or a third
a PD controller and the first, second and third
a first control system that includes an adder that inputs the output from the PID controller or the PD controller and controls the feeding and feeding operations of the wire; and a second control system that controls and maintains the tension of the wire. is provided, and the first control system includes a differentiator that inputs the output from the adder, and a winch valve opening that inputs the output from the differentiator and outputs a first control signal to the control motor. The second control system includes a relief valve pressure setting device that inputs the output from the adder and outputs a second control signal to the relief valve. It is characterized by being

By the way, in order to explain the principle of the present invention,
The characteristics of the mooring wire will be clarified using catenary solutions to prove that the work platform 1 can be maintained in a predetermined position by the feeding and retracting operations of the mooring wire against disturbances such as wind, waves, and currents.

As shown in Figure 6, the x-axis is the seabed surface, the z-axis is perpendicular to the seabed surface, the origin is the O point, and the water depth of the sea area is h.
It is assumed that one end of a sufficiently long wire is pulled by a horizontal force T ₀ at point D, and the wire leaves the seabed surface at point E.

It is assumed that the wire beyond point E is in contact with the seabed surface, and its tip is fixed to the seabed with an anchor.

Here, the x coordinate of point E is _x0 , and the position of the point on the wire is expressed by the distance S measured from point D along the wire.

Now considering a minute portion of length ΔS located at a distance S from point D, the resultant force of the tension 〓 (treated as a vector) acting on this minute portion ΔS satisfies equation (9).

〓(S+△S)−〓(S)=d〓/dS△S……(9
) Also, the external force 〓 (treated as a vector) acting on this minute portion △S is due to its own weight and is considered to be proportional to the length △S, so from equation (9), d〓/dS+〓=0 ...... (10) becomes. And if we consider only gravity as an external force,
Fx=0, Fz=-w, and from equation (10), becomes. Note that w in formula (11) is the weight per unit length of the wire.

Also, if the magnitude of the tension is T, this tension is in the tangential direction of the wire, so From equation (11) Here, T ₀ and S ₀ are integral constants, and S ₀ is the wire length up to the position where Tz=0. Also, T ₀ represents the horizontal tension, and in the catenary solution, the horizontal tension is constant at each point of the wire.

From equations (12) and (13), Here, α=w/T ₀ From equation (14), Then, integrating equation (15), we get Therefore, from equations (14) and (16), dz/dx=α(S-S ₀ )=sinh α(x-x ₀ )...
… (17) Integrating this equation (17), z−z ₀ =1/α{cosh α(x−x ₀ )−1} ……… (18) Note that when x=x ₀ , z=z Set to ₀ .

Also, as shown in Figure 6, since the wire touches the seabed at point E, dz/dx = 0 at point E,
From equation (17), at point E, S=S ₀ , x=x ₀ ......(19). Furthermore, since z=0 at point E (x=x ₀ ), from equation (18), z ₀ = 0 ......(20) Therefore, from equation (18), the catenary solution for the wire is as follows. become that way.

z=1/α{cosh α(x-x ₀ )-1} ...(21) Here, since x=0 and z=h at point D, equation (22) is obtained from equation (21). Formation, horizontal tension
Once T ₀ is determined, x ₀ is determined.

h=1/α(cosh αx ₀ −1)) (22) Moreover, the tension T is expressed as equation (23) from equations (14) and (17).

T=T ₀ cosh α(x−x ₀ ) (23) Furthermore, from equations (17) and (21), the relationship between z and S is obtained as shown in equation (24).

(αz+1) ² −α ² (S−S ₀ ) ² =1
(24) In this equation (24), when S=0 and z=h are substituted, equation (25) is obtained, and the relationship between the horizontal tension T ₀ and the rising wire length S ₀ is obtained.

α ² h ² +2αh=α ² S ² ₀ (25) Next, examine the amount of change in the horizontal tension T ₀ when the force application point D of the wire moves. This corresponds to examining the amount of change in the reaction force, ie, the horizontal tension T ₀ , received from the wire when the work platform 1 moves due to a disturbance force.

Assume that when the force application point D is moved horizontally to the left by Δx to the force application point D' as shown in FIG. 7, the grounding point E of the wire moves by Δx ₀ to point E'. The rising length '' at this time is S ₀ +△S ₀ . The sum of the lengths of the wire portion DE and the wire portion EE′ that is in contact with the seabed is equal to the length of the wire portion D′E′, so the following equation holds true.

+′=S ₀ +△x ₀ =S ₀ +△S ₀ =′′
………(26) Therefore, △S ₀ = △x ₀ ………(27) Next, if the distance from the point of force application to the point of contact is L, the amount of change △L is △L=x ₀ + △x ₀ + △x−x ₀ = △x ₀ + △x
……(28) From formulas (27) and (28), △L=△S ₀ + △x ………(28)′ From formula (28)′, △x=△L−△S ₀ ………( 29) Also, the amount of change ΔT ₀ in the horizontal tension with respect to the amount of movement Δx of the force application point can be determined from the spring constant k of the wire defined by the following equation.

k=△T ₀ /△x=dT ₀ /dx……(30) From formulas (29) and (30) Furthermore, the relationship between the distance L from the force application point to the grounding point and the horizontal tension T ₀ is expressed by equation (32) rather than equation (22).

w/T ₀ h=coshw/T ₀ L−1……(32) From formula (32) From equation (25), h ² +2T ₀ /wh=S ² ₀ ......(34) From equation (34), dS ₀ /dT ₀ =h/wS ₀ ......(35) From equation (17), x= 0, and by substituting S=0, we get
Equation (36) is obtained.

w/T ₀ S ₀ = sinhw/T ₀ L ......(36) From formulas (33) and (36) From equations (31), (35), and (37), From equation (34), S〓-h ₂ /T ₀ = 2h/w ...... (39) From equations (38) and (39), the spring constant k of the horizontal tension with respect to the movement of the force application point is k = S ₀ T ₀ /h ² +LS ₀ -S〓 ......(40) Next, as shown in Fig. 8, attach the wire to the force point D.
If we renormalize by ΔS, then the grounding point E of the wire moves to point E', but since the elongation of the wire is not considered, equation (41) holds true.

S ₀ +△x ₀ = △S+S ₀ +△S ₀ ………(41) Therefore, △S=△x ₀ −△S ₀ ………(42) The distance L from the point of force to the point of contact is Amount of change △L
becomes △L=△x ₀ (43). Therefore, formula (44) holds true from formulas (42) and (43).

△S = △L - △S (44) The spring constant k for wire retraction is as follows.

Here, since the right side of equation (45) is equal to the right side of equation (31), it can be seen that the spring constant for the wire feeding and retracting operation is equal to the spring constant for the movement of the force application point of the wire. Therefore,
The spring constant is obtained from equation (40).

Furthermore, if a wire is stretched with horizontal tension T ₀ in a sea area with a water depth h, the length of the rising wire S ₀ is calculated from equation (25).
is determined, and the distance L from the point of impact to the point of contact is
It can be found as x ₀ from equation (22).

Therefore, the spring constant k in equation (40) is the horizontal tension
It becomes a function of T ₀ .

In this way, the mooring wire can be considered as a type of spring with a spring constant k determined by the horizontal tension T ₀ .
As shown in FIG. 9, the working platform 1 moored with two wires on each side can be considered equivalent to a dynamic system consisting of a mass 15 and a spring 16 as shown in FIG.

Next, it will be shown that the work platform 1 can be kept in a predetermined position by manipulating the mooring wire in response to disturbances.

As shown in FIG. 9, considering the fixed position maintenance control of the work platform 1 moored by two wires on the left and right sides, the equation of motion of the work platform 1 is as follows.

Here, to simplify the explanation, one-dimensional motion in the x-axis direction will be considered.

(m+mx)u=F ₁ +F ₂ +X _A ……(46) x=u……(47) Here, m, m _x ; mass of work platform 1 and additional mass (Kg
m ^-1 sec ² ) u; Speed of work platform 1 (m/s) x; Position of work platform 1 (In Figure 9, the set position of work platform 1 is the origin of the x-axis.) (m) F ₁ ; Mooring reaction force for two wires on the right side (Kg) F ₂ ; Mooring reaction force for two wires on the left side (Kg) X _A ; Disturbance force (Kg) k ₀ ; Spring constant per wire (Kg) /m) k (=2k ₀ ); Equivalent spring constant for two wires (Kg/
m) l ₁ ; Amount of retraction of the right wire (m) l ₂ ; Amount of retraction of the left wire (m) (Note that retraction is positive and retraction is negative.) As shown in Figure 10, the work platform 1 is displaced. The amount of renormalization l required for the wire when x occurs
_1d and l _2d are outputs of a PID controller that receives displacement x as input. That is, l _1d = - (K _P x + K _I ∫xdt + K _D dx/dt) ...... (49) l _2d = - l _1d ...... (50) Here, l _1d ; Required renormalization amount of the right wire (m ) l _2d ; Required renormalization amount of the right wire (m) K _P , K _I , K _D ; Proportional gain, integral gain, and differential gain of the PID controller.

Now, if there is no time delay in the winch wire operation, the wire retraction amounts l ₁ and l ₂ are considered to be equal to the required retraction amounts l _1d and l _2d , so,
Equation (51) holds true.

Then, from equations (49) to (51), l ₁ =-l ₂ =-(K _P x+K _I ∫xdt+K _D dx/dt)...
… (52) Also, from formulas (46) to (48), (m+mx)x¨+2kx−kl ₁ +kl ₂ =X _A …(53) From formulas (52) and (53), (m+ _mx )x¨+2kx+2k (K _P x+K _I ∫xdt+K _D dx/dt=X _A (54) Differentiating this equation (54) with respect to 1 hour, we get
Equation (55) holds true.

(m+m _x )〓+2kK _D x¨ +2k(1+K _P )x〓+2kK _I x=X〓 _A
......(55) Therefore, the characteristic equation G(s) of the closed loop system including the PID controller and the movement characteristics of the work platform is as shown in equation (56).

G(s)=(m+m _x ) s ³ +2kK _D s ² +2k(1+K
_P )s+2kK _I =0 (56) Here, s indicates the Laplace transformer.

Therefore, the three roots s ₁ that make G(s)=0,
A positive number K _P such that the real parts of s ₂ and s ₃ are all negative,
If K _I and K _D are determined, even if a disturbance force is applied to the work platform 1, the work platform 1 can be maintained at a predetermined position by operating the left and right wires.

For example, when m + m _x = 5.454×10 ⁵ (Kgm ^-1 sec ² ) k = 58634.5 (Kg/m) (horizontal tension T ₀ = 15000Kg), K _P , K _I , K _D are K _P = 0.7425 If K _I =0.1581 K _D =5.6486, the three roots s ₁ of the characteristic equation G(s),
s ₂ and s ₃ are s ₁ = −0.1823 s ₂ = −0.2334 s ₃ = −0.7988, and the real parts are all negative, so the working platform 1
It is possible to realize a stable control system that can maintain a predetermined position.

As a result, the work platform 1 assuming one-dimensional movement
A block diagram of the control system for maintaining the position of is shown in FIG. That is, the position of the work platform 1 is detected by the work platform position detector 20, and a deviation signal from the set position is input to the PID controller 17.
The winch 18 is activated in response to the output signal of the PID controller 17, the wire is operated, and the position of the work platform 1 can be maintained. In addition, in Fig. 11,
Reference numeral 19 indicates a black box of the motion characteristic portion of the work platform 1.

Furthermore, a PD controller can be used instead of a PID controller, and in this case, the accuracy will be slightly lower but the responsiveness will be improved.

Hereinafter, a position control device for a work platform as an embodiment of the present invention will be explained with reference to the drawings.
Figure 2 is its configuration diagram, Figure 13 is a schematic diagram for explaining its planar coordinate system, Figure 14 is a graph for explaining the relationship between the pressure in the hydraulic motor piping line and wire tension, and Figure 15. a, b, Figure 16 a~
1, FIGS. 17a and 17b, and FIGS. 18a to 18l are graphs showing simulation results for explaining the effect.

Now, the work platform 1 is provided with a plurality of sets of mooring winch mechanisms, and each mooring winch mechanism includes a pump 04 that sends out oil as a fluid, a winch valve 03 that receives oil from this pump 04, and a winch valve. Control motor 02 that adjusts the opening degree of 03
, a hydraulic motor 06 as a fluid pressure motor rotationally driven by the amount of oil from the winch valve 03, a relief valve 015 that adjusts the high pressure side pressure of the hydraulic motor 06, and a deceleration device that reduces the rotational speed of the hydraulic motor 06. It is composed of a gear 07, a winch drum 08 rotationally driven by the reduction gear 07, a wire 09 paid out or taken in from the winch drum 08, and a tank 010 containing return oil from the winch valve 03.

A position setting device 100 in which predetermined position coordinates (x _s , y _s ) to be maintained by the work platform 1 are set by the worker.
is provided.

Further, an azimuth setting device 101 is provided for setting a predetermined azimuth Ψ _s that the work platform 1 should maintain by the operator. Furthermore, a position/azimuth detector 1 consisting of three light wave distance meters or radio wave distance meters that detects the actual position (x, y) and direction Ψ of the work platform 1
02 is provided.

Output signals x _s , y _s from the position setting device 100 and position/azimuth detector 102; position deviation signals Δx (=x−x _s ), Δy (=y−y _s ), which are the differences between x and y; A first subtracter 103 and a second subtracter 104 are provided, each outputting a first subtractor 103 and a second subtractor 104.

Additionally, a direction setting device 101 and a position/direction detector 10
A third subtractor 10 outputs an azimuth deviation signal ΔΨ (=Ψ−Ψ _s ) which is the difference between the output signal Ψ _s and Ψ.
5 is provided.

By the way, this position deviation converter 106 is provided, and this position deviation converter 106 receives the position deviation signals △x, △y from the first and second subtracters 103, 104, and also performs direction setting. When the azimuth setting signal Ψ _s from the device 101 is input, a position deviation signal △x ₀ in the set azimuth direction and a position deviation signal △y ₀ perpendicular to the set azimuth direction are output based on the calculation formula (57). It is.

In addition, the coordinate positions of these position deviation signals △x ₀ and △y ₀ are the ship position in the coordinate system (x ₀ , y ₀ ) in which the coordinate axes are aligned perpendicularly to the set direction Ψ _s direction in Figure 13. It is expressed as coordinates (△x ₀ , △y ₀ ).

Furthermore, a first PID controller 107 is provided, and this first PID controller 107 inputs the output signal Δx ₀ from the position deviation converter 106 and calculates the wire operation amount for the target winch. This is a controller that outputs a request signal l _xd for the position error signal Δx 0 so that the position deviation signal Δx ₀ becomes zero.

Here, the request signal l _xd for this target winch
becomes like equation (58).

_{I _ _ _ _ _ _} The second PID controller 108 inputs the output signal △y ₀ from the position deviation converter 106 and outputs a request signal _lyd for the wire operation amount to the target winch, so that the position deviation signal △y ₀ becomes zero. This is a controller that makes it so that

Here, the request signal l _yd for this target winch
becomes like equation (59).

l _yd = - {K _P2 △y ₀ + K _I2 ∫△y ₀ dt + K _D2 d/dt (△y ₀ )} ...... (59) Furthermore, a third PID controller 109 is provided, and this third PID controller 109 is provided. The PID controller 109 of No. 3 inputs the azimuth deviation signal ΔΨ from the third subtractor 105, and
This is a controller that outputs a request signal _ld for the wire operation amount to the target winch so that the azimuth deviation signal ΔΨ becomes zero.

Here, the request signal l for this target winch is
_d becomes as shown in equation (60).

l〓 _d = - {K _P3 △Ψ + K _I3 ∫△Ψdt + K _D3 d/dt (△Ψ)} ...... (60) First PID controller 107, second PID controller 1
an adder 11 that inputs each output signal from 08 and the third PID controller 109 and outputs the sum of these signals;
0 is provided, and this adder 110 indicates that the target winch has positional deviations △x ₀ , △y ₀ and azimuth deviations △Ψ
It is now possible to output a wire operation amount request signal _ld that is effective for simultaneously correcting .

Note that the request signal _ld is expressed by equation (61).

l _d = l _xd + l _yd + l〓 _d (61) In addition, the first control system that controls the feeding and feeding of the wire 09 includes a differentiator 111 and a winch valve opening setting device 112. It is configured. That is, the differentiator 111 inputs the wire operation amount request signal ld from the adder 110, differentiates it with respect to time, and outputs a differential signal _l〓d for determining the request signal for the winch rotation speed necessary for wire operation. be.

Furthermore, the winch valve opening setting device 112 determines that the operating speed of the wire 09 is
The first winch rotation speed is equal to
Winch valve opening setting signal θ _d as a control signal for
is output to the control motor 02 via the first control signal line CL1, and the signal _θd from the winch valve opening setting device 112 is expressed by equation (62).

θ _d = K ₁ l〓 _d + θ _d0 (62) Note that θ _d0 is the winch valve opening at the start of control.

Further, the constant K ₁ can be obtained as follows. First, the required rotational speed n _d of the hydraulic motor of the winch necessary to obtain the wire operation speed l〓 _d is given by equation (63).

n _d = r/πDwl〓 _d ………(63) Here, r: Reduction ratio Dw of reduction gear 07; Diameter of winch drum 08 By the way, the flow rate characteristics of the winch valve are as shown in Fig. 5. Since the flow rate is almost proportional to the valve opening except for the dead zone of the opening, the fifth
From the average slope in the figure, the flow rate per unit valve opening, that is, the change in the rotational speed of the hydraulic motor △n, can be obtained, (63)
From the equation, the valve opening request signal θ _d for the winch valve is given by equation (64).

θ _d = n _d / △n + θ _d0 ...... (64) Therefore, from equations (62), (63), and (64), the constant K ₁
can be found as in equation (65).

K ₁ = r/πDw△n ………(65) Furthermore, the second
The control system includes a relief valve pressure setting device 113, which receives the wire operation amount request signal l _d from the adder 110 and outputs a second control signal. Line CL2
A set pressure signal P _d as a second control signal is output to the relief valve 015 via the control signal. In other words, when the wire is stationary, the pressure in the piping path C of the hydraulic motor 06 decreases due to oil leakage in the hydraulic motor 06, and the pressure in the piping path C is adjusted to prevent the wire 09 from being released spontaneously. A set pressure signal P _d can be output to the relief valve 015 so that the pressure can be maintained.

In addition, the wire tension and the piping line C of the hydraulic motor 06
The relationship with the internal pressure is proportional as shown in FIG.

Here, if the slope in Fig. 14 is _K2 , the change in wire tension △T and the piping path C of the hydraulic motor
The pressure change △P ₁ within has the following relationship.

△P ₁ = K ₂ △T ………(66) Also, if the spring constant per wire is k ₀ , the required wire retraction amount l _d is the increment of wire tension expressed by equation (67). Corresponds to ΔT.

ΔT=αk ₀ l _d (67) Here, α is a correction coefficient for the horizontal tension of the wire tension at the winch section.

Therefore, the set pressure signal P _d given to the relief valve 015 is expressed by equation (68).

P _d = P _d0 + K ₂ k ₀ l _d (68) Note that P _d0 is the set pressure signal at the start of control.

The solenoid valve 114 is a valve that is closed during automatic control operation and opened when manual operation is performed, and the replenishment of oil leakage from the hydraulic motor 06 is low when manual operation is performed. Discharge constant pressure pump 01
It is now possible to do it in 3.

Furthermore, as mentioned above, during automatic operation, the solenoid valve 114 is closed, and the hydraulic motor 0
Oil leakage at 6 is caused by pump 04 via winch valve 03.
Replenished by.

Therefore, in automatic operation, oil constantly flows through the winch valve 03, and the winch valve characteristic shown in FIG. 5 in which the flow rate and the valve opening are proportional can be used.

By the way, an automatic manual switching device 115 is provided, and this automatic manual switching device 115 is used for winch valve 0.
The signal from the valve lever 01 of No. 3 and the signal from the winch valve opening setting device 112 are input, and either signal is outputted according to the operator's wishes.

Further, a control motor 02 is provided, and this control motor 02 receives a signal θ _d from a winch valve opening degree setting device 112 supplied via an automatic/manual switch 115, and controls the winch valve opening according to this signal θ _d . It is possible to match the opening degrees of 03.

Furthermore, during automatic operation, the winch valve 03:
A flow path indicated by 〓〓 is always formed, so that the pressure in the piping C of the hydraulic motor 06 is always on the high pressure side, and the piping B forms an oil return circuit and is on the low pressure side. Therefore, the counterbalance valve 011
is always in a closed state.

Further, the wire 09 is fed out by lowering the pressure in the pipe line C, and the wire 09 is drawn in by increasing the pressure in the pipe line C.

That is, when the opening degree of the winch valve 03 is increased, oil enters the pipe line C through the first check valve 05, which increases the pressure in the pipe line C, increases the torque generated by the hydraulic motor 06, and 09 is renormalized.

Also, if the opening degree of winch valve 03 is reduced,
The amount of oil entering the pipeline C through the first check valve 05 decreases, thereby reducing the pressure in the pipeline C and reducing the torque generated by the hydraulic motor 06. As a result, due to the wire tension, The reverse torque applied to the hydraulic motor 06 prevails and the wire is paid out.

Note that the amount of oil that has passed through the hydraulic motor 06 is transferred to the tank 0 after passing through the winch valve 03 through the piping path B.
Return to 10.

Therefore, by changing the opening degree of the winch valve 03, the pressure in the pipe line C is changed, and the wire 0
9 carry-out and carry-in operations can be performed.

The relief valve 015 maintains the pressure in the pipe line C by constantly releasing as little oil as possible to the tank 010. Also relief valve 015
The amount of oil released by the winch valve 03 is from the pump 04.
is constantly replenished through

Furthermore, by replenishing the amount of oil from the winch valve 03, oil leakage from the hydraulic motor 06 is replenished, and at the same time, by controlling the amount of relief at the relief valve 015, the pressure in the piping line C is constantly maintained by the relief valve pressure setting device. The wire tension can be maintained by keeping the output value from 113 at a predetermined value.

In this way, the wire operations necessary to maintain the position of the work platform 1 can be performed, and even in the event of oil leakage from the hydraulic motor 06, the wire tension can be maintained by preventing the wire 09 from flowing out naturally. It's getting old.

In FIG. 12, the same reference numerals as in FIG. 4 indicate substantially the same parts.

Further, the control arithmetic unit including the devices 103 to 113 can be replaced with a control computer.

By the way, the above explanation is about the control means for a certain winch mechanism, but for the remaining winch mechanisms, the devices below each PID controller are provided separately, and in FIG. The branching arrows coming out from the upstream sides of the vessels 107 to 109 indicate the above.

That is, for each winch mechanism, the device 10
0 to 106 are common, and the devices below the first to third PID controllers 107 to 109 are provided separately, so that the optimal control for each winch mechanism can be automatically performed. It is becoming more and more common.

In addition, without making the devices 100 to 106 common,
A system configuration as shown in FIG. 12 may be provided for each winch mechanism. In this case, each
Needless to say, there are no branching arrows from the upstream side of the PID controllers 107 to 109.

Next, we will show the results of a simulation performed on an analog computer to confirm the effectiveness of this device.

As shown in FIG. 9, the target working platform 1 is moored by two wires 5 on the left and right sides, and one-dimensional movement in the wire direction is assumed. Therefore, it is assumed that the two winches 7 on the right side are given the same control command, and the two winches 7 on the left side are also given the same control command.

In addition, the control command received by the winch 7 on the right side,
The sign is opposite to that of the control command received by the left winch 7. That is, when the right winch 7 is given a wire retraction control command, the left winch 7 is given a wire payout control command.

Here, the wire horizontal tension T ₀ is 15000 (Kg), the water depth h is 25 (m), and the wire underwater weight w is 4.46 (Kg/
m), the wire rising length S ₀ and the distance L to the wire grounding point are as follows.

S ₀ =410.7 (m) L = 409.7 (m) Also, from equation (40), the spring constant k ₀ for one wire and the spring constant k for two wires are as follows.

k ₀ = 29300 (Kg/m) k = 2k ₀ = 58600 (Kg/m) And the sum (m+m _x ) of the mass m of the target work platform 1 and the additional mass m _x is as follows.

m+m _x =5.454×10 ⁵ (Kgm ^-1 sec ² ) First, in Figure 15, the period T is 15 seconds and the amplitude A is
2 is a graph showing the positional fluctuation of the work platform 1 when a 10 ton disturbance is applied to the work platform 1 and the position of the work platform 1 is not controlled. The natural period Tc of the moored work platform 1 when position control is not performed in this way is: Since the disturbance force is close to the resonance period Tc, it can be seen that the positional fluctuation of the work platform 1 is quite large.

Further, FIG. 16 is a graph showing the simulation results when the position of the work platform 1 is controlled for the same disturbance force as in FIG. 15, and FIG. 16a is a graph showing the position fluctuation of the work platform 1. Figure 16b is a graph showing the change in disturbance force over time, Figure 16c,
d is a graph showing changes in the winch valve opening of the left and right winches, Figures 16e and f are graphs showing pressure changes in the piping path C of the hydraulic motor 06, and Figures 16g and h are both relief valves. 16 i and j are graphs showing changes in the number of rotations (rotational speed) of winch drum 08, and FIGS. 16 k and 1 are graphs showing changes in the flow rate of wire 09.
It is a graph showing the change in the manipulated variable.

The amount of variation in the work platform 1 when position control is not performed is ±41.3 cm (see Figure 15), whereas the position variation when position control is performed is ±41.3 cm, as shown in Figure 16 a.
4.4 cm, and it can be seen that the positional fluctuation can be suppressed to about 1/10 by controlling the position.

It can be seen from Figures 16c and d that the winch valve opening is approximately 50% at the start of control, but since winch valve 03 has the flow rate characteristics shown in Figure 5, the flow rate through winch valve 03 is approximately 50%. The flow rate is approximately 16% of the maximum flow rate.

In addition, it can be seen from Fig. 16 e and f that the pressure fluctuation in the piping line C of the hydraulic motor 06 is approximately ±25 kg/cm ² , and from Fig. 16 g and h, the pressure fluctuation within the piping line C of the hydraulic motor 06 is approximately ±25 kg/cm 2 .
It can be seen that the flow rate fluctuation of No. 15 is approximately ±14.6 l/min.

Furthermore, from Fig. 16 i and j, the rotation speed fluctuation of winch drum 08 is ±0.13 rps, and Fig. 16 k,
From 1, it can be seen that the amount of wire operation is approximately 15 cm for both feeding and retracting.

Furthermore, it can be seen from FIG. 16 that the responses of the left and right winches are opposite to each other, that is, the phases are inverted.

Next, Fig. 17 is a graph showing the positional fluctuation of the work platform 1 when a step-like disturbance force of 10 (tons) is applied to the work platform 1 and when no position control is performed. It can be seen that the maximum positional variation when not performing is 16 cm.

Furthermore, FIG. 18 is a graph showing the simulation results when the position of the work platform is controlled for the same disturbance force as in FIG. 17, and FIG. Figure 18b is a graph showing the change in disturbance force over time, Figures 18c and d are graphs showing changes in the opening of the winch valve 03 of the left and right winches, and Figure 18e and f are the piping of the hydraulic motor 06. Graph showing pressure changes in passage C, Figure 18g and h are both relief valve 015
FIGS. 18i and 18j are graphs showing changes in the rotational speed of the winch drum 08, and FIGS. 18k and 18 are graphs showing changes in the operating amount of the wire 09.

From Figures 17 and 18, it can be seen that the maximum movement of the work platform 1 when position control is performed is about 6 cm, which is suppressed to about 40% of that when no control is performed, and the movement of the work platform 1 is also fast. You can see that it's suppressed.

From FIGS. 18k and 18, it can be seen that the right winch is settled with the wire retracted, and the left winch is settled with the wire extended.

As a result, the tension in the right wire increases, and in order to counter this increase, as shown in Figure 18e, the pressure within the piping C of the hydraulic motor 06 of the right winch increases, while the tension in the left wire increases. As shown in FIG. 18f, it can be seen that the pressure inside the pipe line C of the hydraulic motor 06 of the left winch is decreasing.

In this way, with this device, by operating the wires using multiple sets of winch mechanisms on the work platform 1, it is possible to automatically maintain the position of the work platform against disturbance forces, and also to maintain the position of the work platform against disturbance forces. It can be seen that the position can be moved automatically.

In addition, the first to third PIDs in the above-mentioned embodiment
Instead of the controllers 107 to 109, the first to third controllers
It is also possible to use a PD controller, in which case:
Since there is no movement, accuracy will be slightly lower, but responsiveness will be faster.

In addition, this device is suitable for use in offshore civil engineering vessels that are held in fixed positions by wires, as well as offshore civil engineering vessels that are held in fixed positions by chains, or oil drilling rigs that are held in fixed positions by chains or wires. It is also suitable for use.

As described in detail above, according to the working boat position control device of the present invention, in a working boat moored by a large number of wires, the set position coordinate signal of the working boat in a predetermined space fixed coordinate system is transmitted. _xs ,
a position setting device that outputs _ys , a direction setting device that outputs a set direction signal _Ψs of the work platform 1, a position coordinate signal x, y of the work platform 1, and a direction signal Ψ
a position/azimuth detector that outputs a position/azimuth detector, and a first input signal _xs from the signal setting device and an output signal x from the position/azimuth detector
and the output signal y _s from the position setting device
and a second subtractor inputting the output signal y from the position and orientation detector, and the output signal Ψ _s from the orientation setter and the output signal Ψ from the position and orientation detector.
and a third subtracter which inputs the output signals from the first and second subtracters and the output signal _Ψs from the azimuth setter to obtain a position deviation signal Δx in the set azimuth direction. ₀ and a positional deviation signal Δy ₀ in a direction perpendicular to the same set direction, and a first PID controller or first PD that receives a positional deviation signal Δy ₀ from the same positional deviation converter. a controller;
A second PID controller or a second PD controller that inputs the positional deviation signal Δy ₀ from the positional deviation converter, and a third PID controller that inputs the azimuth deviation signal ΔΨ from the third subtractor. a third PD controller, and an adder that inputs the outputs from the first, second, and third PID controllers or PD controllers, and controls the feeding and feeding operations of the wire. and a second control system that maintains and controls the tension of the wire,
The first control system includes a differentiator that inputs the output from the adder, and a winch valve opening setting device that inputs the output from the differentiator and outputs a first control signal to the control motor. In addition, the second control system is configured to include a relief valve pressure setting device that inputs the output from the adder and outputs a second control signal to the relief valve. , workers can automatically control the rotational speed of multiple winches and adjust the feeding and retracting of wires through optimal procedures without having to operate the levers of multiple winches. It has the advantage that it can be stably held at the position and azimuth desired by the operator automatically and with extremely high precision.

[Brief explanation of the drawing]

Figures 1 to 3 show the system for holding the work platform in place; Figure 1 is a plan view, Figure 2 is an elevation view, and Figure 3 shows the system from the work platform to land. FIG. 4 is a schematic diagram for explaining a method of calculating each predetermined distance of Graphs 6 to 11 showing the relationship between valve opening degree and oil amount are for explaining the principle of the present invention, and Figures 6 to 8 are graphs for clarifying the characteristics of the mooring wire from catenary solution. 9 is an explanatory diagram showing the state of the mooring wire in the sea, FIG. 9 is a plan view showing the working platform moored by the mooring wire, and FIG. 10 is an equivalent diagram corresponding to FIG. 9 replaced with a mechanical system. The schematic diagram shown in Fig. 11 is a block diagram thereof, and Fig. 12 to 18 are
The figures show a position control device for a work platform as an embodiment of the present invention. FIG. 12 is a configuration diagram thereof, FIG. 13 is a schematic diagram for explaining its planar coordinate system, and FIG. 14 is a diagram thereof. Graph for explaining the relationship between hydraulic motor piping pressure and wire tension, 1st
5a, b, 16a-l, 17a, b, and 18a-l are graphs showing simulation results for explaining the effect. 01...Winch valve lever, 02...Control motor, 03...Winch valve, 04...Pump, 05
...First check valve, 06...Hydraulic motor, 07...
...Reduction gear, 08...Winch drum, 09...
Wire, 010...tank, 011...counter balance valve, 012...throttle, 013...low discharge constant pressure pump, 014...second check valve, 015
... Relief valve, 100 ... Position setting device, 101
... Direction setter, 102 ... Position and direction detector, 1
03...First subtractor, 104...Second subtractor, 105...Third subtractor, 106...Position error converter, 107...First PID controller, 108
...Second PID controller, 109...Third PID controller, 110...Adder, 111...Differentiator, 1
12... Winch valve opening setting device, 113... Relief valve pressure setting device, 114... Solenoid valve, 115...
...Automatic manual switching device, CL1, CL2...Control signal line.

Claims (1)

[Claims] 1. A winch valve 03 whose opening degree is adjusted by a control motor 02, and a fluid pressure motor 06 which is rotationally driven by fluid supplied through the winch valve 03.
and the above-mentioned fluid pressure motor 06 around which the wire 09 is wound.
A work platform 1 is equipped with a plurality of sets of mooring winch mechanisms each having a winch drum 08 that is rotationally driven by a winch drum 08 and a relief valve 015 that adjusts the high-pressure side pressure of the fluid pressure motor 06. A position setting device 100 that outputs set position coordinate signals x _s , y _s of the work platform 1 in a coordinate system.
, an azimuth setting device 101 that outputs a set azimuth signal Ψ _s of the work platform 1, and a position/azimuth detector 102 that outputs the position coordinate signals x, y and the azimuth signal Ψ of the work platform 1; A first input device receives the output signal _xs from the position setting device 100 and the output signal x from the position/direction detector 102.
a second subtractor 104 inputting the output signal _ys from the position setting device 100 and the output signal y from the position and orientation detector 102;
A third subtractor 105 inputs the output signal Ψ _s from the azimuth setter 101 and the output signal Ψ from the position/azimuth detector 102; A position error converter that inputs each output signal and the output signal Ψ _s from the azimuth setting device 101 and outputs a position deviation signal Δx ₀ in a set azimuth direction and a position error signal Δy ₀ in a direction perpendicular to the set azimuth. 106 and the same position deviation converter 106
A first PID controller 107 or a first PD controller that inputs the position error signal _{Δx 0 from} the position error converter 106, and a second PID controller 108 or a second PD controller, a third PID controller 109 or a third PD controller inputting the azimuth deviation signal ΔΨ from the third subtractor 105, and the first, second, and third PD controllers; A first control system includes an adder 110 that inputs the output from the PID controllers 107 to 109 or the PD controller, and controls the feeding and feeding operations of the wire 09, and maintains and controls the tension of the wire 09. A second control system is provided,
The first control system includes a differentiator 111 that inputs the output from the adder 110, and a winch valve opening that inputs the output from the differentiator 111 and outputs a first control signal to the control motor 02. a relief valve pressure setting device 113 configured to include a setting device 112, and the second control system inputs the output from the adder 110 and outputs a second control signal to the relief valve 015; A position control device for a work platform, characterized by comprising: