KR20120001287A - Method for controlling sway of workpiece - Google Patents

Abstract

PURPOSE: A method for controlling the shaking of products is provided to load containers on the exact location by controlling the shaking of products which is being transported. CONSTITUTION: A method for controlling the shaking of products comprises followings. Control input comprises first control input and second control input. The first control input is applied on a trolley(104) according to the transfer direction of the trolley. The second control input is applied on a spreader(105) by the tension of an additional rope. The shaking of the product in the transfer direction of the trolley is controlled by the input of the first control input, and the shaking of the product in the direction perpendicular to the transfer direction of the trolley is controlled by the second control input.

Description

How to control the shaking of the object to be transported {METHOD FOR CONTROLLING SWAY OF WORKPIECE}

The present invention relates to a method of controlling the shaking of a conveyed object by a crane in transporting the conveyed object by a crane, and more particularly, by using a crane mounted on a platform moving such as a mobile harbor. When transporting, a container suspended on a long rope is severely shaken due to internal factors due to the movement and stoppage of the trolley and external factors due to waves, wind, etc. The present invention provides a sliding surface for the movement of the trolley. To control the longitudinal sway in the trolley transport direction, and to control the lateral sway perpendicular to the trolley transport direction by using torque control for additional ropes added to the spreader. .

Recently, with the increase of intercity trade between countries, the volume of transportation is also increasing. Among them, the volume of transportation through sea lanes with low transportation cost is increasing dramatically. As described above, containers have been used for a long time in order to load as much cargo as possible in the logistics through sea, that is, in order to facilitate the convenience and speed of loading and unloading the transported goods.

In general, cranes are used for loading or unloading containers into vessels. However, due to the internal factors caused by the movement and stoppage of the trolley and external factors due to waves and winds when transporting the container using a crane, containers suspended on long ropes are not only transported in the trolley but also in the longitudinal direction of the trolley. Severe shaking in the lateral direction perpendicular to the direction, which greatly affects the efficiency and safety of the crane.

For this reason, many studies have been carried out to improve the working efficiency of the crane by suppressing the shaking of the container. Among them, Korean Patent No. 0369585 relates to “the system and method for suppressing the shaking of cranes,” which is different from the prior art which directly measures the shaking angle by using a vision sensor. Or an estimator mounted on the top of the trolley to estimate acceleration during load transfer, a trolley drive that controls the movement of the trolley, and an estimator for estimating the shaking state of the load based on data transmitted from the trolley drive and the acceleration sensor And a control system for transmitting the estimated data to the trolley drive and a control method thereof.

In addition, Korean Laid-Open Patent Publication No. 2006-0073704 relates to a method for controlling the position and vibration of a ceiling crane, and provides feedback control to control the vibration of a rope while the overhead crane moves from a current position to a target position. Disclosed are a position and a shaking control method of a ceiling crane which can be transferred to a target position while controlling by a method.

On the other hand, Korean Patent Laid-Open Publication No. 2005-0007246 filed by the present applicant relates to a method for controlling the container shake of a crane, a method of controlling the shake using the movement of a trolley, and active that is used for earthquake resistance in high-rise buildings. Disclosed is a method of deriving and implementing control force that can dampen container shaking while reducing the transport distance and working time of a container using a method of an active mass damper system.

The above-described conventional techniques are based on the assumption that the crane is fixed to a place where there is no movement such as a pier, and in this case, the shaking motion of the container to be transported and the movement of the trolley exist in a common plane. In this case, the shaking of the object to be conveyed can be controlled only by the movement of the trolley, and thus, the shake of the object can be sufficiently controlled by the above-described conventional control technology.

However, when a crane is installed in a marine structure such as a mobile harbor or a ship, the marine structure in which the crane is installed is rocked by the influence of waves and winds, and the transferred object suspended from the crane The longitudinal sway in the conveying direction of the trolley is of course greatly shaken in the lateral direction perpendicular to the conveying direction of the trolley. However, since the lateral sway movement of the object to be transported does not exist in the coplanar with the trolley movement in the transport direction of the trolley, in the prior art, the object to be suspended by a crane installed in a marine structure is known. Shake cannot be suppressed.

The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a control method capable of controlling the shaking in the direction of movement of the trolley as well as the shaking in the direction perpendicular thereto.

In order to achieve the above object, according to an embodiment of the present invention, a load supporting rope for supporting the object to be transported in a linear direction with respect to the crane structure, and the spreader and the coupling coupled to the object to the trolley; In the object movement control method for controlling the shaking of the object by adding a control input to the object to be conveyed of the crane including an additional rope to add an external force to the spreader in a direction perpendicular to the transport direction of the trolley, The control input includes a first control input applied to the trolley with respect to the transport direction of the trolley, and a second control input applied to the spreader by tension of the additional rope, the first control input being used in the transport direction of the trolley. Controlling the shaking of the conveyed material, the conveyed object in a direction perpendicular to the conveying direction of the trolley by a second control input The blood feed water shake control method, characterized in that for controlling the vibration is provided.

According to a preferred embodiment of the present invention, the object shake control method is characterized in that the object to be transported to the set sliding surface s (Sliding surface s) in the direction perpendicular to the conveying direction and the conveying direction, sliding mode control ( Provided is a method of controlling an object to be shaken by sliding mode control.

According to a further preferred embodiment of the present invention, the control input of the object shaking control method, (S1) obtaining the equation of motion of the trolley and the object of the conveyed object by a lagrange equation; (S2) obtaining a relationship between the tension of the additional rope and the second control input; (S3) setting an error vector including a position error and a swing error of the trolley and a sliding plane s based on the three-dimensional equation of motion of the crane; (S4) obtaining a lyapunov function V (t) by a sliding mode control method and differentiating the function with respect to time; (S5) determining the first control input and the second control input such that the function obtained by differentiating the Lyapunov function with respect to time becomes -μ | s | so as to have asymptotic stability. A determined object shake control method is provided.

According to the method of controlling the object to be shaken according to the present invention, it is possible to control the shake in the conveying direction of the trolley as well as the shake in the direction perpendicular thereto, so that the container can be loaded quickly and accurately at the target position. This has the effect of improving the processing capacity of the crane.

1 is a state diagram showing a docked marine structure and a mother ship mounted crane according to an embodiment of the present invention.
2 is a view showing the direction of movement of the offshore structure is mounted crane according to an embodiment of the present invention.
3 is a block diagram illustrating a shake control method according to an exemplary embodiment of the present invention.
4 is a diagram illustrating a coordinate system for analyzing the motion of a crane-mounted offshore structure according to an embodiment of the present invention.
5 is a view showing the connection and arrangement of the rope in the crane according to an embodiment of the present invention.
Figure 6 is a side view showing the connection and arrangement of the rope disposed between the trolley and the spreader in the crane according to an embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention, but the present invention is only an example and the present invention is not limited thereto. .

FIG. 1 is a perspective view illustrating a docking state of a mobile harbor for carrying a mother ship carrying a large amount of containers to be transported and a container mounted on a mother ship.

Figure 2 illustrates the various movements that can occur in offshore structures, such as mobile harbors on which cranes are mounted. Translational movements in the x, y, and z directions are called surging, swaging, and heaving, respectively. Further, rotational movement movements in the x, y, and z directions are referred to as rolling, pitching, and yawing, respectively. As shown in Fig. 1, when the mobile harbor is docked on a much larger mothership, other movements are negligible, and only the rolling, pitching, and heaving motions can be considered to represent the movements.

3 is a block diagram illustrating a shake control method according to an exemplary embodiment of the present invention. Hereinafter, each step will be described in detail with reference to FIGS. 4 to 6.

The first step is to use the Lagrange equation to derive the equations of motion of crane-mounted systems on offshore structures (eg, mobile harbors) that are rocked by waves or wind. As described above, only the rolling, pitching, and heaving motions are considered in such a marine structure.

4 shows a coordinate system used to derive the equation of motion. O _o X _o Y _o Z _o is the reference coordinate system, O _s X _s Y _s Z _s is the ship coordinate system, the origin is the center of gravity of the ship. O _t X _t Y _t Z _t is the trolley coordinate system whose origin is the center of the trolley. m _t and m _p are the mass of the trolley and the conveyed material, respectively, and h is the height of the crane. x and y are the positions of the gantry and trolley in the ship coordinate system, respectively. l indicates the length of the load bearing rope. θ and δ are shaking angles in the trolley conveying direction and lateral shaking angles perpendicular to the trolley conveying direction, respectively. θ and δ are the values measured in the trolley. f _y is a control input applied to the trolley in the trolley transport direction to control the shaking in the trolley transport direction. z is the hebbing direction position of the marine structure. φ and ψ are rolling angles and pitching angles of the marine structure with respect to the reference coordinate system. In the reference coordinate system, the position vector p _t of the trolley and the position vector p _l of the object to be conveyed are expressed as follows.

식 (1)

Formula (1)

식 (2)

Equation (2)

The position vector p _t of the trolley and the position vector p _l of the conveyed object are differentiated with respect to time, and the velocity vector v _{t of the} trolley and the velocity vector v _l of the conveyed object can be obtained as follows.

식(3) 및 (4)

Equations (3) and (4)

here,

to be.

The kinetic energy and potential energy of the system including the trolley and the conveyed object are as follows. It should be noted that the kinetic energy and potential energy of the offshore structure are not included in the above equations, and the ship's rolling, pitching and heaving motion are considered disturbances.

식 (5)

Equation (5)

식 (6)

Formula (6)

Next, using the lagrange equation, it is possible to obtain the equation of motion of the trolley and the object to be transported in the crane mounted on the marine structure such as the mobile harbor which is shaken by the waves or the wind. The equation of motion is

식 (7)

Formula (7)

식 (8)

Formula (8)

식 (9)

Formula (9)

here,

to be.

The second step is to analyze the mechanism of generating torque using an additional rope to suppress lateral shaking to derive control input for lateral shaking.

In the following, the structure of the crane of this embodiment will be described first with reference to FIGS. 5 and 6 before inducing a control input.

As shown in FIG. 5, the crane of the embodiment includes four load supporting ropes 102, 102 ′, 102 ″, 102 ′ ″ and two additional ropes 202, 202 ′. Figure 2 omitted the specific structure of the crane and is shown around the connection of the rope. Specifically, the crane is largely supported by a crane structure (not shown), a girder (not shown) supported by it, a trolley 104 traversing from side to side along the girder, and a load support via the trolley 104. And a spreader 105 supported by ropes 102, 102 ', 102 ", 102' ", which rises toward or descends from trolley 104 side according to adjustment of the rope length. A container is fixedly coupled to the spreader 105 to lift, move, and lower the container as the spreader 105 rises, moves, and descends, and loads and unloads the container.

The tips of the load bearing ropes 102, 102 ′, 102 ″, 102 ′ ″ are fixed to the hoist drum 101, and are wound on the hoist drum 101 or rotated by the hoist drum 101. 101). In this embodiment, all four load supporting ropes 102, 102 ', 102' ', 102' '' are all secured to ensure that the load supporting ropes are wound on the hoist drum by the same length or unwound by the same length from the hoist drum. Is configured to be wound around one hoist drum 101, the load supporting rope may be wound around a plurality of hoist drums as long as the balance of the spreader 105 can be maintained.

The load bearing ropes 102, 102 ′, 102 ″, 102 ′ ″ are provided via trolley pulleys 106, 106 ′, 106 ″, 106 ′ ″ disposed at four corners on the trolley 104. Trolley pulleys 108, 108 ′, 108 which extend to spreader pulleys 107, 107 ′, 107 ″, 107 ′ ″ disposed at four corners on spreader 105, and in turn are installed at four corners on trolley 104. '', 108 '' ', and the rear end thereof is fixed to the actuators 103, 103', 103 '', 103 '' '.

Load hoisting ropes 102, 102 ', 102 ", 102' " are mounted using a hoist drum 101 that fixes the tips of the load carrying ropes 102, 102 ', 102 ", 102' ". When it is wound up, the length of the load supporting ropes 102, 102 ', 102 ", 102' " becomes short, so that the spreader 105 rises toward the trolley 104. FIG. In contrast, when the hoist drum 101 unwinds the load supporting ropes 102, 102 ′, 102 ″, 102 ′ ″, the length of the load supporting ropes 102, 102 ′, 102 ″, 102 ′ ″. Lengthens, and the spreader 105 descends away from the trolley.

The rear ends of the load supporting ropes 102, 102 ', 102 ", 102' " are fixed to the actuators 103, 103 ', 103 ", 103' ", and are driven by the actuators. 102, 102 ', 102' ', 102' '' can be precisely adjusted. Since the actuators 103, 103 ', 103 " and 103' " finely adjust the lengths of the load supporting ropes 102, 102 ', 102 " and 102' ", the posture of the spreader 105 It is used to control.

For example, the direction of movement of the trolley 104 is referred to as the x direction, and the direction perpendicular to the direction of movement of the trolley 104 on the surface formed by the trolley 104 is referred to as the y direction and perpendicular to these x and y. If one direction is called the z direction, the rotation of the spreader in the x direction is called Trim, the rotation in the y direction is called List, the rotation in the z direction is called Skew, and the spread of the spreader using the six values The posture can be displayed. That is, the parallel movement of the spreader 105 may be represented by the values of x, y, and z, and the rotational movement of the spreader 105 may be displayed by the values of Trim, List, and Skew.

The four load-bearing ropes 102, 102 ', 102' ', 102' '' are each independently driven actuators 103, 103 ', 103' ', 103' '' and precisely controlled in length. With this, x, y, z, Trim, List and Skew values can also be precisely controlled. By appropriately adjusting these values, it is possible to control the spreader to take an arbitrary posture.

Next, the additional ropes 202 and 202 'will be described. The tips of the additional ropes 202, 202 ′ are fixedly coupled to the hoist drum 101. When the hoist drum 101 winds up the additional ropes 202, 202 ′, the length of the rope substantially used to support the spreader 105, that is, the additional drums 203, 203 ′ described later from the hoist drum 101. The length of additional ropes 202, 202 'leading to decreases. When the additional rope 202 is unwound from the hoist drum 101, the length of the additional ropes 202, 202 'described above is increased. The additional ropes 202, 202 ′ are pulled from the hoist drum 101 via trolley pulleys 204, 204 ′ on the trolley 104 in a direction perpendicular to the direction of movement of the trolley 104. Spreader pulleys 206, 206 ′ on the spreader 105 via trolley pulleys 205, 205 ′ disposed in an outwardly protruding portion (eg, about 1.5 m) outside the side, 106 ″, 106 ′ ″. )

The spreader pulleys 206, 206 ′ are positioned inward of the spreader pulleys 107, 107 ′, 107 ″, 107 ′ ″ via the load bearing ropes 102, 102 ′, 102 ″, 102 ′ ″. Is placed. Placing the spreader pulleys 206, 206 ′ on the inside (eg, about 2.5 m) results in a smaller angle between the additional ropes 202, 202 ′ with the trolley 104, thus providing the same additional rope 202, 202 ') The movement amount of the spreader 105 in the lateral direction can be increased with respect to the change in the length.

In addition, the container is generally stacked in multiple layers in order to increase the loading density of the vessel, when the container is loaded using a crane often occurs when the crane must work between the containers. At this time, since the additional ropes 202 and 202 'extend from the portion protruding laterally than the spreader 105 to the lower spreader 105, the additional ropes 202 and 202' protrude laterally than the spreader 105. ) May cause interference with neighboring containers. In this embodiment, the spreader pulleys 206 and 206 'are arranged inside the spreader pulleys 107, 107', 107 " and 107 '", so that such interference does not occur as much as possible.

The additional ropes 202, 202 ′ then pass through the trolley pulleys 207, 208; 207 ′, 208 ′ on the trolley 104 again via the spreader pulleys 206, 206 ′. ') Is fixedly coupled. The additional drums 203, 203 'wind up or unwind additional ropes 202, 202' according to the direction of rotation, thereby controlling the length of the additional ropes 202, 202 '.

In addition, actuators 221 and 221 'are provided on the hoist drum 101 side. When the actuators 221, 221 ′ control the moving pulleys 222, 222 ′ back and forth (the direction of the trolley's movement), the additional ropes 202, 202 ′ are pulled or released, thereby additional ropes 202. 202 ') is adjusted. As such, by adjusting the length of the additional ropes 202, 202 ′, the attitude and lateral shaking of the spreader 105 can be controlled.

As described above, the additional ropes 202, 202 'support the spreader 105 in a diagonal direction when viewed from the front as shown in FIG. Therefore, increasing or decreasing the length of the additional ropes 202 and 202 'causes the spreader 105 to move in the left and right directions (the direction perpendicular to the direction of motion of the trolley). In this embodiment, when the spreader 105 is shaken laterally due to disturbance, the spreader 105 is adjusted by precisely adjusting the lengths of both additional ropes 202 and 202 'by using the actuators 221 and 221'. You can reduce the shaking of the.

Figure 6 shows the trolley, the spreader and the conveyed object as seen from the front of the movement direction of the trolley. Where a is the distance from the center of the spreader to the pulleys 206, 206 ′ supporting additional ropes on the spreader. b is the distance from the center of the trolley to the pulleys 205, 205 ′, 207, 207 ′ supporting additional ropes on the side of the trolley. f ₁ and f ₂ are the tensions of the additional ropes. τ is the control torque applied to the spreader to suppress lateral shaking. The control torque can be obtained by appropriately adjusting the tension f ₁ and f ₂ of the additional rope. δ is the swing angle in the lateral direction perpendicular to the trolley transport direction as described above. The control torque for suppressing lateral shaking is as follows.

식 (10)

Formula (10)

Note that the additional rope tension cannot be negative, so the following inequality must be satisfied:

식 (11)

Formula (11)

Where f _min and f _max are the minimum and maximum tensions allowed for the additional rope, respectively. The minimum tension should ensure that the additional rope is pulled firmly and the maximum tension should be less than the tension of the load bearing rope. If the tension of the additional rope at the start of work is f _o and Δf is the control input, the tension of the additional rope is as follows.

식 (12)

Formula (12)

Substituting equation (12) into equation (10), the control torque is obtained as follows.

식 (13)

Formula (13)

here,

to be.

The third step is to define an error vector including a trolley position error and a swing error and a sliding surface, based on the three-dimensional motion equations of the crane installed in the offshore structure such as the mobile harbor which is oscillating. . The error vector is defined as

식 (14)

Formula (14)

Here, y _d , θ _d and δ _d are target values of the trolley position and target values of the swing angle, respectively. In the following, it is assumed that θ _d and δ _d are zero.

Next, a sliding surface is defined as follows.

식 (15)

Formula (15)

을 제어하여

일 때,

으로 접근할 수 있으면, 이 제어는 t≥t₁에서

을 얻게 할 수 있다(여기서, t₁은 유한값의 상수). 즉, 시스템의 흔들림을 억제하고, 소정 시간 내에 피이송물을 목표 위치에 안착시킬 수 있는 것이다. 따라서, 시스템의 흔들림을 안정하게 억제하기 위해서는 시스템이 슬라이딩 평면 s에 점근안정성(asymptotic stability)을 갖도록 하는 제어 입력을 구하면 된다.Where k ₁ , k ₂ And k ₃ is the positive gain gain. It should be noted that since the movement of the trolley and the swing angle in the direction of the trolley transport are coupled, the control of the movement of the trolley controls the position of the trolley as well as the swing angle in the direction of the trolley transport. s and

By controlling

when,

Is accessible from t≥t ₁

Can be obtained, where t ₁ is a finite constant. In other words, the shaking of the system can be suppressed, and the object to be conveyed can be seated at the target position within a predetermined time. Therefore, in order to stably suppress the shaking of the system, it is necessary to obtain a control input for allowing the system to have asymptotic stability in the sliding plane s.

가 되도록 하여 시스템이 점근안정성을 갖도록 하는 제어 입력을 유도하는 것이다.In the fourth and fifth stages, a function obtained by deriving a lyapunov function by sliding mode control method and deriving the function with respect to time to prove asymptotic stability of the system is obtained.

By inducing the control input to make the system asymptotic stable.

To obtain the Lyapunov function, the derived equation of motion is modified as follows.

식 (16)

Formula (16)

Substituting equation (13) into equation (16)

식 (17)

Formula (17)

Can be obtained.

here,

to be.

If we obtain the Lyapunov function by the sliding mode control method, and differentiate it with respect to time, we can get the following equation.

식 (18)

Formula (18)

Using the equations (14) and (15), this Lyapunov function is differentiated over time.

식 (19)

Formula (19)

Is obtained.

라고 정의하면, 리아프노프 함수의 미분식은 식 (17)을 이용하여 다음과 같이 쓸 수 있다.

, The differential expression of the Lyapunov function can be written as

식 (20)

Formula (20)

In order for the system to have asymptotic stability, Eq. (20) must be -μ | s |. From this relation, we derive the control input to make the system asymptotic stability as follows.

식 (21)

Formula (21)

Here, mu = diag (μ _y , μ _δ ), and μ _y and μ _δ are integers.

It should be noted that in order to prevent a chattering phenomenon, sgn (s) in equation (21) for control input is defined as follows.

식 (22)

Formula (22)

In short, when transporting consignments such as containers using cranes mounted on offshore structures, such as mobile harbors, consignments suspended on ropes due to internal factors due to the movement and stopping of trolleys and external factors due to waves and wind. Water vibrates not only in the transport direction of the trolley but also in the lateral direction perpendicular thereto. The present invention uses the movement of the trolley to control the longitudinal sway in the direction of the transport of the trolley while the torque is controlled using an additional rope. By controlling the lateral sway (lateral sway) through, by adopting the sliding mode control method as a control method it is possible to control the shake stably and quickly.

In the above-described offshore structure equipped with a crane according to the present invention, the method of controlling the shaking of the object to be transported has been described as a specific embodiment. However, the present invention is not limited thereto, and the present invention is not limited thereto. It should be construed as having the broadest range. Those skilled in the art can vary each step depending on the field of application, and combinations / substitutions of the disclosed embodiments can be carried out on methods that are not timely addressed, but this is also within the scope of the present invention. In addition, those skilled in the art can easily change or modify the disclosed embodiments based on the present specification, it is apparent that such changes or modifications belong to the scope of the present invention.

101: hoist drum 102,102 ', 102'',102''': load supporting rope
103,103 ', 103``, 103''': Actuator
104: trolley 105: spreader
106,106 ', 106'',106''': trolley pulley
106,106 ', 106``, 106''': Spreader Pulleys
202,202 ': additional rope 203,203': additional drum
205,205 ': trolley pulley
206,206 ': Spreader pulley
221,221 ': Actuator for additional rope

Claims (6)

A trolley for transferring the object to be transported in a linear direction with respect to the crane structure, a load supporting rope for supporting the object to be conveyed and a spreader coupled to the object, and perpendicular to the conveying direction of the trolley to the object to be conveyed; In the object shake control method for adding a control input to the object to be conveyed of the crane including an additional rope that can add an external force in one direction,
The control input includes a first control input applied to the trolley with respect to the transport direction of the trolley, and a second control input applied to the spreader by the tension of the additional rope,
Controlling the shaking of the object to be conveyed in the conveying direction of the trolley by the first control input,
Characterized in that for controlling the shaking of the object to be conveyed in a direction perpendicular to the conveying direction of the trolley by the second control input
How to control the shaking of the object. The method of claim 1,
The method of controlling the object to be shaken may control the object to be transported in a sliding mode s so that the object is converged in the conveying direction and in a direction perpendicular to the conveying direction.
How to control the shaking of the object. The method according to claim 1 or 2,
And the second control input is a torque input with respect to the conveying direction of the object to be conveyed to the object to be conveyed by the tension of the additional rope.
How to control the shaking of the object. The method of claim 3, wherein
The control input of the object to be shaken control method,
(S1) obtaining a motion equation of the trolley of the crane and the object to be conveyed by a lagrange equation;
(S2) obtaining a relationship between the tension of the additional rope and the second control input;
(S3) setting an error vector e and a sliding plane s including a position error and a swing error of the trolley based on the three-dimensional equation of motion of the crane;
(S4) obtaining a lyapunov function V (t) by a sliding mode control method and differentiating the function with respect to time;
(S5) A function obtained by differentiating the Lyapunov function with respect to time in order to have asymptotic stability

(here,

Is determined by determining the first control input and the second control input to be a constant).
How to control the shaking of the object. The method of claim 4, wherein
The Lyapunov function V (t) is

Characterized by
How to control the shaking of the object. The method of claim 4, wherein
The crane is installed in the offshore structure,
In calculating the equation of motion of the object to be transported, only the moving, rolling and pitching motions of the sea floating body are considered.
How to control the shaking of the object.

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