Method for verifying underwater compensation precision of AHC crane

Abstract

The invention provides a verification method for underwater compensation precision of an AHC crane, and the method comprises the steps: recording an initial position, and then recording the distance of a marking point after the marking point moves upwards relative to the initial position and the distance of the marking point after the marking point moves downwards relative to the initial position; therefore, the height difference after the output end of the main arm rotates upwards corresponds to the downward moving distance of the mark point relative to the initial position, and the height difference after the output end of the main arm rotates downwards corresponds to the upward moving distance of the mark point relative to the initial position. Whether the actual distance of the load moving up and down underwater is within the height difference range after the output end of the main arm rotates upwards or within the height difference range after the output end of the main arm rotates downwards is compared, and then whether the up-down floating distance of the load underwater accords with the length of a steel wire rope winding and unwinding rope after the crane starts active compensation or not can be verified. Therefore, the collaboration of the active compensation of the overwater crane and the up-down floating of the underwater load is ensured.

Description

Technical Field

[0001] This invention relates to the field of crane technology, and specifically to a method for verifying the underwater compensation accuracy of an AHC crane. Background Technology

[0002] With the development of technology in my country, marine development is becoming easier, and the types and quantities of offshore operations are increasing. At the same time, harsh environments such as wind and waves at sea can affect the safety and accuracy of offshore operations. The underwater compensation technology of AHC cranes can actively adjust the position of the spreader by monitoring the heave and sag of the ship in real time, so as to prevent overloading of the lifting equipment or imbalance of the cargo caused by wave fluctuations. It is of great significance in marine engineering applications.

[0003] For example, Chinese patent application CN201810676943.4, published on June 11, 2019, discloses a winch-type active and passive heave compensation device and its working method, belonging to the field of marine operation technology. It includes a winch, a platform acceleration sensor, a rotary encoder, a PLC controller, and a vector frequency conversion system. The winch is connected to a fixed pulley and a movable pulley via a rope and support frame. A tension sensor is installed above the fixed pulley. The rotary encoder is connected to the winch's drum shaft. The outputs of the tension sensor, rotary encoder, and platform acceleration sensor are all connected to the PLC controller, and the output of the PLC controller is connected to the vector frequency conversion system. The winch includes a winch drum, a winch drum shaft, a hydraulic disc brake, and a planetary reducer. One planetary gear of the planetary reducer is connected to a passive compensation control component via a first coupling, and the other planetary gear is connected to an active compensation control component. The winch-type active and passive heave compensation device is symmetrically arranged along both sides of the winch drum.

[0004] The aforementioned patent document addresses the issues of low motor power and insufficient accuracy by combining active and passive compensation methods in a winch-type heave compensator and utilizing hydraulic and hydropneumatic systems for energy recovery and storage. However, it does not verify the actual compensation of the load underwater to ensure that the adjusted actual compensation distance is within the preset theoretical compensation range. Summary of the Invention

[0005] The purpose of this invention is to provide a method for verifying the underwater compensation accuracy of an AHC crane. First, the height difference between the crane output end and the initial position after active compensation is calculated. Then, the height difference between the underwater load and the vertical floating of the load relative to the initial position is recorded. The range of the height difference between the two is compared to accurately verify whether the actual compensation distance of the underwater load is within the compensation range of the crane output end after active compensation, thereby ensuring the synergy between the active compensation of the water crane and the vertical floating of the underwater load.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for verifying the underwater compensation accuracy of an AHC crane, which is implemented by moving a load up and down in water using a crane and a testing device. The testing device includes a marking component located underwater and a measuring component disposed on one side of the load and fitted onto the marking component; the method includes the following steps: S1 synchronously deploys the marking component and the measuring component to the preset underwater target position. After the marker body of the marking component floats to the surface of the water, the crane lowers the load to the preset underwater target position via the wire rope and stops there to determine the initial position of the marker point on the measuring component. S2 obtains the first angle between the main boom and the base at the initial position and the second angle between the main boom and the base after the main boom rotates upward through the data acquisition device. Based on the second angle and the length of the main boom, the actual upward movement distance of the wire rope is determined. S3 uses an image acquisition sensor to record the first endpoint position of the marker point on the measurement component after the main arm and folding arm rotate upward, causing the underwater load to move upward; S4 obtains the third included angle between the main boom and the base after the main boom rotates downward through the data acquisition device, and determines the actual downward movement distance of the wire rope based on the third included angle and the length of the main boom. S5 uses an image acquisition sensor to record the second endpoint position of the marker point on the measurement component after the main arm and folding arm rotate downwards, causing the underwater load to move downwards; S6 calculates the first height difference between the first endpoint position and the initial position, and the second height difference between the second endpoint position and the initial position. Then, it determines whether the first height difference is within the actual upward movement distance of the wire rope and whether the second height difference is within the actual downward movement distance of the wire rope, in order to verify whether the actual movement distance of the load underwater matches the active compensation length of the wire rope.

[0007] The above method first records the initial position, which facilitates subsequent recording of the distance the marker point moves upward and downward relative to the initial position. This allows the height difference after the main boom output end rotates upward to determine the upward movement distance of the wire rope. Then, the upward movement distance of the wire rope is compared with the downward movement distance of the marker point relative to the initial position. The height difference after the main boom output end rotates downward corresponds to the upward movement distance of the marker point relative to the initial position, verifying the rationality of the active compensation rope winding and unwinding method. By comparing whether the actual vertical movement distance of the load underwater falls within the height difference range after the main boom output end rotates upward and downward respectively, it can be verified whether the vertical floating distance of the load underwater matches the length of the wire rope winding and unwinding after the crane activates active compensation, thus ensuring the coordination between the active compensation of the water crane and the vertical floating of the underwater load.

[0008] Furthermore, step S4 also includes: obtaining the third included angle between the main arm and the base after the main arm rotates downward through the data acquisition device, then calculating the fourth vertical distance from the hinge point of the main arm and the folding arm to the base respectively, then determining the height difference after the main arm output end rotates downward through the difference between the fourth vertical distance and the second vertical distance, and determining the actual downward movement distance of the wire rope according to the preset relationship table between the height difference after the main arm output end rotates downward and the actual downward movement distance of the wire rope.

[0009] The above settings can calculate the distance from the main boom output end to the base corresponding to the initial position, and use this distance as a reference to facilitate the height difference between the main boom output end and the reference after the main boom output end rotates downward. Then, the actual downward movement distance of the wire rope is determined by the preset relationship table between the height difference after the main boom output end rotates downward and the actual downward movement distance of the wire rope, which is then converted into the downward movement distance of the wire rope, so as to facilitate the determination of whether the wire rope winding and unwinding meet the requirements.

[0010] Furthermore, step S2 also includes: calculating the first vertical distance from the hinge point of the main arm and the folding arm to the base at the initial time based on the main arm length and the first included angle; calculating the second vertical distance from the hinge point of the main arm and the folding arm to the output end of the folding arm after the main arm rotates upward based on the main arm length and the second included angle; determining the height difference after the output end of the main arm rotates upward based on the difference between the first vertical distance and the second vertical distance; and determining the actual upward movement distance of the wire rope based on the preset relationship table between the height difference after the output end of the main arm rotates upward and the actual upward movement distance of the wire rope.

[0011] The above settings can calculate the distance from the main boom output end to the base corresponding to the initial position, and use this distance as a reference to facilitate the height difference between the main boom output end and the reference after the main boom output end rotates upward. Then, the actual upward movement distance of the wire rope is determined by the preset relationship table between the height difference after the main boom output end rotates upward and the actual upward movement distance of the wire rope, which is then converted into the upward movement distance of the wire rope, so as to facilitate the determination of whether the wire rope winding and unwinding meet the requirements.

[0012] Furthermore, the marking component includes a marking body, a marking rope, and a weight. The upper end of the marking rope is fixedly connected to the marking body, and the lower end of the marking rope is fixedly connected to the weight. The marking rope has two or more marking points, which are spaced apart and have equal spacing.

[0013] The above settings facilitate recording the distance the measuring component moves up and down relative to the marker point.

[0014] Furthermore, the measuring assembly includes two or more fixed rods, limiting rings, and measuring rods. A connecting seat is provided on one side of the load. The fixed rods are arranged relatively parallel to each other in the vertical direction. One end of the fixed rod is fixed to the connecting seat by a locking member. The limiting ring is fixed to the other end of the fixed rod by a locking member. The measuring rod, perpendicular to the fixed rod, is arranged between the limiting rings. The marking rope passes through the limiting ring.

[0015] The above settings enable the underwater load to move the measuring rod synchronously, while the limit ring can limit the marking rope, reducing the lateral movement of the marking rope caused by wave fluctuations.

[0016] Furthermore, the measuring rod is provided with progressively increasing scales, the measuring rods are arranged relatively parallel to each other, and there are two or more scale rods between the measuring rods and located at corresponding scales, with the scale rods being arranged perpendicular to the measuring rods.

[0017] The above settings, via the scale rod, enable the image acquisition sensor to clearly record the distance the measuring rod moves relative to the marker point.

[0018] Furthermore, step S1 also includes: Before the "marking component and measuring component move synchronously to the preset target position on the water surface", the upper end of the marking rope is fixedly connected to the marking body, and then the lower end of the marking rope is fixedly connected to the weight after passing through the limiting ring.

[0019] The above settings ensure that the marker rope passes through the limit rings and descends underwater with the weight, so as to facilitate subsequent recording of the distance the marker point moves between the limit rings.

[0020] Furthermore, step S1 also includes: During the process of "deploying the marker component to the preset underwater target location", the crane lowers the load via a wire rope until the limit ring descends below the water surface and stops.

[0021] The above setup ensures that the marker floats on the water surface after the weight descends to the seabed, thus ensuring that the marker rope below the water surface is taut.

[0022] Furthermore, step S1 also includes: The image acquisition sensor records the reference scale value on the measuring rod when the marked point is in its initial position.

[0023] The above settings are to facilitate subsequent recording of the difference between the measuring rod and the reference scale value after the measuring rod moves up and down relative to the mark point.

[0024] Furthermore, step S5 also includes: The image acquisition sensor records the second scale value on the measuring rod when the marker point moves upward relative to the initial position and reaches the second endpoint position; Step S3 also includes: The image acquisition sensor records the first scale value on the measuring rod when the marker point moves downward relative to the initial position and reaches the first endpoint.

[0025] The above settings facilitate the calculation of the downward movement of the measuring rod relative to the marker rope and the upward movement of the measuring rod relative to the marker rope, thereby enabling the calculation of the actual range of the vertical movement of the measuring rod relative to the marker rope.

[0026] Furthermore, step S6 also includes: The first height difference between the first scale value on the measuring rod corresponding to the first endpoint position and the reference scale value is compared with the actual upward movement distance of the wire rope to verify whether the first height difference is within the range of the actual upward movement distance of the wire rope. The second height difference between the second scale value on the measuring rod corresponding to the second endpoint position and the reference scale value is compared with the actual downward movement distance of the wire rope to verify whether the second height difference is within the range of the actual downward movement distance of the wire rope. Then, it is determined whether the actual vertical movement distance of the load underwater matches the active compensation length of the wire rope.

[0027] The above settings can determine whether the first height difference and the second height difference of the underwater load's vertical movement are within the actual upward or downward movement distance of the wire rope, and thus determine whether the actual movement distance of the load underwater is in line with the length of the wire rope's active compensation winding and unwinding rope. Attached Figure Description

[0028] Figure 1 This is a flowchart of the process of the present invention.

[0029] Figure 2 This is a schematic diagram showing the connection between the marking component and the measuring component in the invention.

[0030] Figure 3 This is a schematic diagram showing the connection between the marking component and the measuring component in the invention from another perspective. Figure 4 This is a schematic diagram showing the position of the crane after it rotates upward and downward in this invention. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] like Figure 2-3As shown, a method for verifying the underwater compensation accuracy of an AHC crane is implemented by moving a load up and down in water using a crane and a testing device. The testing device includes a marking component located underwater and a measuring component mounted on the side of the load 9 and fitted onto the marking component. The marking component includes a marking body 1, a marking rope 2, and a weight 3. The upper end of the marking rope 2 is fixedly connected to the marking body 1, and the lower end of the marking rope 2 is fixedly connected to the weight 3. The marking rope 2 has two or more marking points 4, which are spaced apart and equally spaced. The measuring component includes two or more fixing rods 5, a limiting ring 6, and a measuring rod 7. In this embodiment, there are two fixing rods 5, two limiting rings 6, and two measuring rods 7. A connecting seat 8 is provided on one side of the load 9. The two fixing rods 5 are arranged relatively parallel to each other and are in the same vertical plane. One end of the fixing rod 5 is fixed to the connecting seat 8 by a locking member. A connecting ear (not shown in the figure) is provided on the outside of the limiting ring 6, through which the locking member passes. The other end of the fixed rod 5 is fixed. The fixed rod 5, the connecting seat 8, the limiting ring 6 and the connecting ear are all provided with through holes that match the locking parts. The locking parts are bolts and nuts that match the bolts. The measuring rod 7, which is perpendicular to the fixed rod 5, is set between the limiting rings 6. The measuring rod 7 is fixed between the limiting rings 6 by the locking parts. The marking rope 2 passes through the limiting ring 6 and is located between the two measuring rods 7. The measuring rod 7 is provided with progressively increasing scales. The measuring rods 7 are arranged relatively parallel to each other. There are two or more scale rods 12 between the measuring rods 7 and at the corresponding scales. The scale rods 12 are arranged perpendicular to the measuring rods 7. In this embodiment, the scales on the measuring rods 7 and the scale rods 12 are made of reflective material. A light source 10 is provided on one side of the load 9 and is arranged parallel to the fixed rod 5. The light source 10 is a waterproof flashlight. The irradiation direction of the light source 10 is perpendicular to the side of the measuring rod 7 that is provided with scales and is arranged opposite to the light source 10.

[0033] like Figure 1 and Figure 4 As shown, the crane includes a base 01, a main boom 02, a folding boom 03, a winch 04 mounted on the main boom, a wire rope 05 wound on the winch, and a data acquisition device 06 mounted on the base. It also includes the following specific steps: S1 First, the upper end of the marking rope 2 is fixedly connected to the marking body 1. Then, the lower end of the marking rope 2 passes through the limiting ring 6 and is fixedly connected to the weight 3, ensuring that the marking rope 2 descends underwater with the weight 3 after passing through the limiting ring 6. The marking component and the measuring component are moved synchronously to the preset target position on the water surface. Then, the weight 3 is dropped to the preset target position underwater, and at the same time, the crane drives the load 9 to descend via the wire rope until the limiting ring 6 descends to the water surface and stops. After the marking body 1 of the marking component floats out of the water, the marking rope 2 is just taut. In this embodiment, the marking body 1 is a float, and the weight of the weight 3 is greater than the net buoyancy of the marking body 1. The net buoyancy of body 1 is greater than the weight of the marker rope 2 in the water, causing the crane to lower the load 9 along the vertical direction of the marker rope 2 to the target position underwater via the wire rope and stop there. Then, the image acquisition sensor 11 fixed on one side of the measuring component records the initial position of the marker point 4 on the measuring rod 7 of the measuring component, that is, the reference scale value on the measuring rod 7 when the marker point 4 is in the initial position. The image acquisition sensor 11 is a waterproof camera. The image acquisition sensor 11 is set parallel to the light source 10 and is on the same horizontal line as the midpoint of the measuring rod 7 to ensure that the captured picture can accurately read the marker point 4 at the corresponding scale.

[0034] S2 obtains the first included angle between the main arm and the base after the main arm rotates upward using a data acquisition device. Then, it calculates the first vertical distance from the hinge point of the main arm and the folding arm to the base initially, and the second vertical distance from the hinge point of the main arm and the folding arm to the output end of the folding arm after upward rotation. Based on the difference between the first and second vertical distances, it determines the upward movement distance of the wire rope. In this embodiment, the data acquisition device is an attitude sensor, and the "first vertical distance from the hinge point of the main arm and the folding arm to the base" is calculated in step S2.1. S2.1 Taking the plane where the main arm and the base hinge are located as the reference plane 07, draw a first straight line perpendicular to the reference plane through the hinge of the main arm and the folding arm, so that the main arm, the first straight line and the reference plane form a right triangle. In the right triangle, the length of the main arm is L and the first included angle between the main arm and the base at the initial position is a1. Calculate the first perpendicular distance Q1 from the hinge of the main arm and the folding arm to the reference plane using trigonometric functions, as shown in formula (1). Q1 = L*sin a1 (1); S2.2 The length of the main arm is L. After the main arm rotates upward in the initial position, the first included angle between the main arm and the base is a2. The first vertical distance Q2 from the hinge point of the main arm and the folding arm to the base is calculated by trigonometric functions, as shown in formula (2). Q2=L*sin a2(2; The height difference after the main boom output end rotates upward is determined by the difference between the first vertical distance Q1 and the second vertical distance Q2. Then, the actual upward movement distance of the wire rope is determined according to the preset relationship table between the height difference after the main boom output end rotates upward and the actual upward movement distance of the wire rope.

[0035] After the main arm and the folding arm rotate upwards, causing the underwater load to move upwards, the load 9 drives the measuring rod 7 to move upwards relative to the marking assembly. The image acquisition sensor 11 records the first scale value corresponding to the first endpoint position on the measuring rod 7 after the marking point 4 moves downwards relative to the initial position.

[0036] S4 obtains the third included angle a3 between the main arm and the base after the main arm rotates downward through the data acquisition device, and then calculates the fourth vertical distance Q4 from the hinge point of the main arm and the folding arm to the base. Then, the height difference after the main arm output end rotates downward is determined by the difference between the fourth vertical distance Q4 and the second vertical distance Q2. The actual downward movement distance of the wire rope is determined according to the preset relationship table between the height difference after the main arm output end rotates downward and the actual downward movement distance of the wire rope.

[0037] S5 records, through the image acquisition sensor, the downward rotation of the main arm and the folding arm causing the underwater load to move downward, the load 9 causing the measuring rod 7 to move downward relative to the marking assembly, and the marking point 4 moving upward relative to the initial position, corresponding to the second scale value at the second end position on the measuring rod 7.

[0038] S6 calculates the first height difference between the first endpoint position and the initial position, that is, by comparing the first height difference between the first scale value on the measuring rod corresponding to the first endpoint position and the reference scale value with the actual upward movement distance of the wire rope, to verify whether the first height difference is within the range of the actual upward movement distance of the wire rope; then calculates the second height difference between the second endpoint position and the initial position, that is, by comparing the second height difference between the second scale value on the measuring rod corresponding to the second endpoint position and the reference scale value with the actual downward movement distance of the wire rope, to verify whether the second height difference is within the range of the actual downward movement distance of the wire rope; and then determines whether the actual vertical movement distance of the load underwater matches the active compensation length of the wire rope.

[0039] The working principle of this invention is as follows: First, the initial position is recorded to facilitate subsequent recording of the distances the marker point moves upward and downward relative to the initial position. This allows the height difference after the main boom output end rotates upward to determine the upward movement distance of the wire rope. Then, the upward movement distance of the wire rope is correlated with the upward movement distance of the marker point relative to the initial position, and the downward movement distance of the wire rope is correlated with the downward movement distance of the marker point relative to the initial position. After active compensation and retraction of the wire rope, the actual vertical movement distance of the load underwater is compared to whether it falls within the height difference range after the main boom output end rotates upward and downward, respectively. This verifies whether the vertical floating distance of the load underwater matches the length of the wire rope retraction after the crane activates active compensation, thus ensuring the coordination between the active compensation of the water crane and the vertical floating of the underwater load.

Claims

1. A method for verifying the underwater compensation accuracy of an AHC crane, implemented by moving a load vertically in water using a crane and a testing device, the testing device comprising a marking component located underwater and a measuring component disposed on one side of the load and sleeved on the marking component; characterized in that: Includes the following steps: S1 synchronously deploys the marking component and the measuring component to the preset underwater target position. After the marker body of the marking component floats to the surface of the water, the crane lowers the load to the preset underwater target position via the wire rope and stops there to determine the initial position of the marker point on the measuring component. S2 obtains the first angle between the main boom and the base at the initial position and the second angle between the main boom and the base after the main boom rotates upward through the data acquisition device. Based on the second angle and the length of the main boom, the actual upward movement distance of the wire rope is determined. S3 uses an image acquisition sensor to record the first endpoint position of the marker point on the measurement component after the main arm and folding arm rotate upward, causing the underwater load to move upward; S4 obtains the third included angle between the main boom and the base after the main boom rotates downward through the data acquisition device, and determines the actual downward movement distance of the wire rope based on the third included angle and the length of the main boom. S5 uses an image acquisition sensor to record the second endpoint position of the marker point on the measurement component after the main arm rotates downward and drives the underwater load downward. S6 calculates the first height difference between the first endpoint position and the initial position, and the second height difference between the second endpoint position and the initial position. Then, it determines whether the first height difference is within the actual upward movement distance of the wire rope and whether the second height difference is within the actual downward movement distance of the wire rope, in order to verify whether the actual movement distance of the load underwater matches the active compensation length of the wire rope.

2. The method for verifying the underwater compensation accuracy of an AHC crane according to claim 1, characterized in that: Step S4 further includes: obtaining the third included angle between the main arm and the base after the main arm rotates downward through the data acquisition device, then calculating the fourth vertical distance from the hinge point of the main arm and the folding arm to the base respectively, then determining the height difference after the main arm output end rotates downward through the difference between the fourth vertical distance and the second vertical distance, and determining the actual downward movement distance of the wire rope according to the preset relationship table between the height difference after the main arm output end rotates downward and the actual downward movement distance of the wire rope.

3. The method for verifying the underwater compensation accuracy of an AHC crane according to claim 1, characterized in that: Step S2 further includes: calculating the first vertical distance from the hinge point of the main arm and the folding arm to the base at the initial time based on the main arm length and the first included angle; calculating the second vertical distance from the hinge point of the main arm and the folding arm to the output end of the folding arm after the main arm rotates upward based on the main arm length and the second included angle; determining the height difference after the output end of the main arm rotates upward based on the difference between the first vertical distance and the second vertical distance; and determining the actual upward movement distance of the wire rope based on the preset relationship table between the height difference after the output end of the main arm rotates upward and the actual upward movement distance of the wire rope.

4. The method for verifying the underwater compensation accuracy of an AHC crane according to claim 1, characterized in that: The marking assembly includes a marking body, a marking rope, and a weight. The upper end of the marking rope is fixedly connected to the marking body, and the lower end of the marking rope is fixedly connected to the weight. The marking rope has two or more marking points, which are spaced apart and have equal spacing.

5. The method for verifying the underwater compensation accuracy of an AHC crane according to claim 1, characterized in that: The measuring assembly includes two or more fixed rods, limiting rings, and measuring rods. A connecting seat is provided on one side of the load. The fixed rods are arranged relatively parallel to each other in the vertical direction. One end of the fixed rod is fixed to the connecting seat by a locking member. The limiting ring is fixed to the other end of the fixed rod by a locking member. The measuring rod, perpendicular to the fixed rod, is arranged between the limiting rings. The marking rope passes through the limiting rings.

6. The method for verifying the underwater compensation accuracy of an AHC crane according to claim 1, characterized in that: The measuring rod has progressively increasing scales, and the measuring rods are arranged relatively parallel to each other. There are two or more scale rods between the measuring rods and located at corresponding scales, and the scale rods are arranged perpendicular to the measuring rods.

7. The method for verifying the underwater compensation accuracy of an AHC crane according to claim 1, characterized in that: Step S1 also includes: Before the "marking component and measuring component move synchronously to the preset target position on the water surface", the upper end of the marking rope is fixedly connected to the marking body, and then the lower end of the marking rope is fixedly connected to the weight after passing through the limiting ring.

8. The method for verifying the underwater compensation accuracy of an AHC crane according to claim 1, characterized in that: Step S1 also includes: During the process of "deploying the marker component to the preset underwater target location", the crane lowers the load via a wire rope until the limit ring descends below the water surface and stops. The image acquisition sensor records the reference scale value on the measuring rod when the marked point is in its initial position.

9. The method for verifying the underwater compensation accuracy of an AHC crane according to claim 1, characterized in that: Step S5 also includes: The image acquisition sensor records the second scale value on the measuring rod when the marker point moves upward relative to the initial position and reaches the second endpoint position; Step S3 also includes: The image acquisition sensor records the first scale value on the measuring rod when the marker point moves downward relative to the initial position and reaches the first endpoint.

10. The method for verifying the underwater compensation accuracy of an AHC crane according to claim 1, characterized in that: Step S6 also includes: The first height difference between the first scale value on the measuring rod corresponding to the first endpoint position and the reference scale value is compared with the actual upward movement distance of the wire rope to verify whether the first height difference is within the range of the actual upward movement distance of the wire rope. The second height difference between the second scale value on the measuring rod at the second endpoint position and the reference scale value is compared with the actual downward movement distance of the wire rope to verify whether the second height difference is within the range of the actual upward movement distance of the wire rope. Then determine whether the actual vertical movement distance of the load underwater matches the length of the active compensation rope of the wire rope.

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