Offshore crane heave compensation control system and method using visual ranging

Abstract

Provided is an offshore crane heave compensation control system and method using video rangefinding to achieve heave compensation in a directly driven pump-controlled electro-hydraulic heave compensator. The heave compensation and the heave compensator are applicable for special operation and control requirements on a fixed offshore platform and allow the crane to achieve steady lifting of a load away from or lowering of a load on to a supply vessel without being influenced by the motion of the supply vessel caused by ocean currents, ocean winds, or ocean waves. Also provided is a test platform for the offshore crane heave compensation control system using video rangefinding. The test platform provides a realistic simulation for all lifting and lowering processes of an offshore platform crane in offshore environments to study the motion control of the provided system.

Claims

1. An heave compensation control system using visual ranging for an offshore crane, comprising: a detecting device, a controlling device and an actuating device, the heave compensation control system is configured to achieve heave motion compensation automatically while the offshore crane is loading down and up cargo to a supply vessel, by adding a movement with the same direction and same amplitude to the supply vessel; wherein: the detecting device is configured to detect a three-dimensional position information of the supply vessel using a visual ranging method, and transmit the detected parameters of three-dimensional position information to the controlling device, the controlling device is configured to control the actuating device to achieve heave compensation movement automatically while the offshore crane is loading down and up the cargo to the supply vessel, by adding the movement with the same direction and amplitude to the supply vessel; the offshore crane is positioned on a fixed offshore platform; the three-dimensional position information means displacement, velocity and acceleration information in various directions which is referred to a rectangular coordinate system including the heave direction and the three-dimensional attitude of the supply vessel; and the movement with the same amplitude and same direction means the supply vessel moves along with a periodic motion of the ocean waves with the same amplitude and same direction.

2. The heave compensation control system of claim 1, wherein: during a loading up stage, the detecting device is configured detect heave motion information of the supply vessel using the visual ranging method, and the controlling device is configured to compute velocity and acceleration information of the supply vessel; by adding the movement with the same amplitude and same direction to the supply vessel heave motion, the actuating device is configured to perform active heave motion compensation and choose a right time for loading up, so as to avoid impact loads of crane wire ropes.

3. The heave compensation control system of claim 1, wherein: during a loading down stage, the detecting device is configured to detect the three-dimensional position information of the supply vessel using the visual ranging method; under the control of the controlling device, the actuating device is configured to add the movement with the same amplitude and same direction to the supply vessel during the loading down stage, to ensure that the cargo is down to a vessel deck of the supply vessel at a relative setting speed; the actuating device is further configured to judge attitude information of the supply vessel and choose a right time for loading down, so as to load down the cargo steadily.

4. The heave compensation control system of claim 1, wherein: the actuating device is a direct pump control electro-hydraulic heave compensation device (3) comprising a servo motor driver (4), a rotation speed sensor (5), a displacement sensor (7), and at least three pressure sensors (6); the servo motor driver (4) is configured to drive the direct pump control electro-hydraulic heave compensation device (3); the rotation speed sensor (5), the displacement sensor (7), and the at least three pressure sensors (6) are configured to collect operating parameters of the direct pump control electro-hydraulic heave compensation device (3) and feed the collected operating parameters back to the controlling device for achieving a closed-loop control of the direct pump control electro-hydraulic heave compensation device (3), in order to load down and up the load steadily and stably.

5. The heave compensation control system of claim 4, wherein: the direct pump control electro-hydraulic heave compensation device (3) comprises the servo motor driver (4), a servo motor (16), a two-way hydraulic pump (17), an accumulator (13), a quick connector (14), two overflow valves (15), a single rod hydraulic cylinder (11), a movable pulley (9), a static pulley (10), the at least three pressure sensors (6), the rotation speed sensor (5), and the displacement sensor (7); the servo motor driver (4) is configured to drive the servo motor (16) and therefore rotate the two-way hydraulic pump (17); two output terminals of the two-way hydraulic pump (17) are connected to a rod chamber and a rodless chamber of the single rod hydraulic cylinder (11) respectively through a hydraulic pipeline; two overflow valves, which are oppositely arranged, are connected in parallel between the two output terminals of the two-way hydraulic pump (17); the servo motor (16) is connected to the rotation speed sensor (5); the rotation speed sensor (5), the displacement sensor (7), the servo motor driver (4), and the at least three pressure sensors (6) are respectively connected to the controlling device which is a control computer (1); the movable pulley (9) is connected to a piston rod of the single rod hydraulic cylinder (11); the static pulley (10) is connected to a bottom of the single rod hydraulic cylinder (11); the displacement sensor (7) is installed in the single rod hydraulic cylinder (11).

6. The heave compensation control system of claim 5, wherein: the servo motor driver (4), the servo motor (16), the two-way hydraulic pump (17), the accumulator (13), the quick connector (14), the two overflow valves (15), the single rod hydraulic cylinder (11), the movable pulley (9), the static pulley (10), the at least three pressure sensors (6), the rotation speed sensor (5), and displacement sensor (7) are integrated into an autonomous device.

7. The heave compensation control system of claim 5, wherein: the movable pulley (9), the piston rod of the single rod hydraulic cylinder (11) and the static pulley (10) of the direct pump control electro-hydraulic heave compensation device (3) are located on the same axis.

8. The heave compensation control system of claim 5, wherein: after a first way of the accumulator (13) of the direct pump control electro-hydraulic heave compensation device (3) is connected to a first terminal of the two pilot operated check valves (18) which are oppositely arranged, a second terminal of the two pilot operated check valves (18) is connected in parallel between the two terminals of the two-way hydraulic pump (17).

9. The heave compensation control system of claim 5, wherein: the accumulator (13) is divided into three ways, the three ways comprises the first way, a second way and a third way; wherein the first way is connected to the rod chamber of the single rod hydraulic cylinder (11), the second way is connected to the quick connector (14), and the third way is connected to a first pressure sensor (6) of the at least three pressure sensors; the at least three pressure sensors at least comprises the first pressure sensor, a second pressure sensor and a third pressure sensor; wherein the two output terminals of the two-way hydraulic pump (17) are respectively connected to the second pressure sensor (6) and the third pressure sensor (6).

10. The heave compensation control system of claim 1, wherein: the controlling device is the control computer (1), the detecting device is an industrial camera (2), and the actuating device is a direct pump control electro-hydraulic heave compensation device (3); the industrial camera (2) and the direct pump control electro-hydraulic heave compensation device (3) are connected to the control computer (1) via electrical connection wiring (8) respectively; the industrial camera (2) and the direct pump control electro-hydraulic heave compensation device (3) are respectively mounted on an offshore crane base; information and energy exchange is carried out between the direct pump control electro-hydraulic heave compensation device (3) and the control computer (1), which and forms a closed-loop motion control, in order to load down and up the load steadily and stably.

11. The heave compensation control system of claim 1, comprising a control method for controlling the heave compensation control system; wherein the control method includes the following steps: detecting the three-dimensional position information of the supply vessel by the detecting device using visual ranging method; transmitting the detected parameters of the three-dimensional position information of the supply vessel to the controlling device to control the actuating device to perform heave motion compensation while the offshore crane is loading up and down the cargo; and adding the movement with the same amplitude and same direction of heave motions to the supply vessel during the loading up stage and the loading down stage.

12. The heave compensation control system of claim 11, wherein the control method includes the loading up stage and the loading down stage; during the loading up stage, the detecting device detects the heave motion information of the supply vessel using visual ranging method, and the controlling device computes the velocity and acceleration information of the supply vessel; by actuating device adds the motion of the same amplitude and same direction to the supply vessel, the actuating device performs active heave motion compensation and choose the right time for loading up, so as to avoid the impact loads of the crane wire ropes; during the loading down stage, the detecting device detects the three-dimensional position information of the supply vessel using the visual ranging method; under the control of the controlling device, the actuating device adds the movement with the same amplitude and same direction to the supply vessel heave motion during the loading down stage, to ensure that the cargo is down to the vessel deck of the supply vessel at a relative setting speed; the actuating device is further configured to judge the attitude information of the supply, and choose the right time for loading down, so as to load down the cargo steadily.

13. A testbed for the heave compensation control system of claim 1, wherein the testbed includes a hydraulic oil source (19), a hydraulic control valve (20), a control handle (21), a hydraulic winch (22), the actuating device, the controlling device, the detecting device, a rack (30), a simulated load (26), a 6-DOF platform (27), a control cabinet for power distribution (29) and a tension sensor (25); the actuating device and the detecting device are installed on the rack (30), a first terminal of a wire rope (24) is connected to the simulated load (26) via the actuating device, a second terminal of the wire rope (24) is connected to the hydraulic winch (22); the hydraulic control valve (20) is connected to the hydraulic oil source (19), the control handle (21) and the hydraulic winch (22) respectively; the simulated load (26) is loaded up and down by the control handle (21); the simulated load (26) is placed on the 6-DOF platform (27); the 6-DOF platform (27) and the control cabinet for power distribution (29) are combined together to simulate the vessel motion of the supply vessel on the ocean; the control cabinet for power distribution (29), actuating device and detecting device are connected to the controlling device respectively.

14. The testbed of claim 13, wherein the actuating device is the direct pump control electro-hydraulic heave compensation device (3), including a servo motor driver (4), a rotation speed sensor (5), a displacement sensor (7), and at least three pressure sensors (6).

15. The testbed of claim 14, wherein the actuating device is the direct pump control electro-hydraulic heave compensation device (3) includes the servo motor driver (4), the servo motor (16), a two-way hydraulic pump (17), an accumulator (13), a quick connector (14), two overflow valves (15), a single rod hydraulic cylinder (11), a movable pulley (9), a static pulley (10), the at least three pressure sensors (6), the rotation speed sensor (5), and the displacement sensor (7); the servo motor driver (4) is configured to drive the servo motor (16) and therefore rotate the two-way hydraulic pump (17); two output terminals of the two-way hydraulic pump (17) are connected to a rod chamber and a rodless chamber of the single rod hydraulic cylinder (11) respectively through a hydraulic pipeline; the two oppositely mounted overflow valves, which are oppositely arranged, are connected in parallel between the two output terminals of the two-way hydraulic pump (17); the servo motor (16) is connected to the rotation speed sensor (5); the rotation speed sensor (5), the displacement sensor (7), the servo motor driver (4), and the at least three pressure sensors (6) are respectively connected to the controlling device which is a control computer (1); the movable pulley (9) is connected to a piston rod of the single rod hydraulic cylinder (11); the static pulley (10) is connected to a bottom of the single rod hydraulic cylinder (11); the displacement sensor (7) is installed in the single rod hydraulic cylinder (11).

16. The testbed of claim 14, wherein the controlling device is a control computer (1), and the detecting device is an industrial camera (2)); the industrial camera (2) and the direct pump control electro-hydraulic heave compensation device (3) are connected to the control computer (1) via electrical connection wiring (8) respectively.

17. The testbed claim 16, wherein a sensor group (28), the industrial camera (2), and the servo motor driver (4) in the direct pump control electro-hydraulic heave compensation device (3) are connected to the control computer (1), respectively.

18. The testbed claim 14, wherein a first terminal of a wire rope is connected to a simulated load (26) through the static pulley (10), the movable pulley (9) and a tension sensor (25) in the direct pump control electro-hydraulic heave compensation device (3), and a second terminal of the wire rope (24) is connected to the hydraulic winch (22).

19. A direct pump control electro-hydraulic heave compensation device using the heave compensation control system of claim 1, wherein the direct pump control electro-hydraulic heave compensation device (3) is the actuating device of the heave compensation control system; the direct pump control electro-hydraulic heave compensation device (3) comprises a servo motor driver (4), a servo motor (16), a two-way hydraulic pump (17), an accumulator (13), a quick connector (14), two overflow valves (15), a single rod hydraulic cylinder (11), a movable pulley (9), a static pulley (10), at least three pressure sensors (6), a rotation speed sensor (5), and a displacement sensor (7); the servo motor driver (4) is configured to drive the servo motor (16) and therefore rotate the two-way hydraulic pump (17); two output terminals of the two-way hydraulic pump (17) are connected to a rod chamber and a rodless chamber of a single rod hydraulic cylinder (11) respectively; the two overflow valves, which are oppositely arranged, are connected in parallel between the two output terminals of the two-way hydraulic pump (17); the servo motor (16) is connected to the rotation speed sensor (5); the rotation speed sensor (5), the displacement sensor (7), the servo motor driver (4), and the at least three pressure sensors (6) are respectively connected to the controlling device which is a control computer (1); the movable pulley (9) is connected to a piston rod of the single rod hydraulic cylinder (11); the static pulley (10) is connected to a bottom of the single rod hydraulic cylinder (11); and the displacement sensor (7) is installed in the single rod hydraulic cylinder (11).

20. The direct pump control electro-hydraulic heave compensation device of claim 19, wherein after a first way of the accumulator (13) of the direct pump control electro-hydraulic heave compensation device (3) is connected to a first terminal of two pilot operated check valves (18) which are mounted oppositely, a second terminal of the two pilot operated check valves (18) is connected in parallel between the two terminals of the two-way hydraulic pump (17).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a structural diagram of an offshore crane heave compensation control system using visual ranging.

(2) FIG. 2 is a structural diagram of a direct pump control type electro-hydraulic heave compensation device according to example 1.

(3) FIG. 3 is a structural diagram of a direct pump control type electro-hydraulic heave compensation device according to example 2.

(4) FIG. 4 is a structural diagram of a test platform of an offshore crane heave compensation control system using visual ranging.

NOTES

(5) 1, control computer; 2, industrial camera; 3, direct pump control electro-hydraulic heave compensation device; 4, servo motor driver; 5, rotation speed sensor; 6, pressure sensor; 7, built-in displacement sensor; 8, electrical connection wiring; 9, movable pulley; 10, static pulley; 11, single rod hydraulic cylinder, 12, hydraulic pipeline, 13, accumulator, 14, quick connector, 15, overflow valve, 16, servo motor, 17, two-way hydraulic pump, 18, Pilot operated check valve, 19, hydraulic oil source, 20, hydraulic control valve, 21, control handle, 22, hydraulic winch, 23, hydraulic pipeline, 24, wire rope, 25, tension sensor, 26, simulated load, 27, 6-DOF platform, 28, sensor group, 29, control cabinet for power distribution, 30, rack.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) The present invention will be In some embodiments described below with reference to the accompanying drawings and embodiments. The following embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the contents described in the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Embodiment 1

(7) Referring to FIG. 1, the offshore crane heave compensation control system using visual ranging in the present invention includes a control computer 1, an industrial camera 2 and direct pump control electro-hydraulic heave compensation device 3. The industrial camera 2 and the servo motor driver 4, rotation speed sensor 5, three pressure sensors 6 and built-in displacement sensor 7 in the direct pump control electro-hydraulic heave compensation device 3 are respectively connected to the control computer 1 via electrical connection wiring 8 to exchange information and energy; the industrial camera 2 and the direct pump control electro-hydraulic heave compensation device 3 are respectively mounted on the offshore crane base.

(8) Referring to FIG. 2, the direct pump control electro-hydraulic heave compensation device 3 in the first embodiment includes a servo motor driver 4, a servo motor 16, a two-way hydraulic pump 17, an accumulator 13, a quick connector 14, two overflow valves 15, a single rod hydraulic cylinder 11, a movable pulley 9, a static pulley 10, three pressure sensors 6, a rotation speed sensor 5, and a displacement sensor 7.

(9) The servo motor driver 4 drives the servo motor 16 to rotate the two-way hydraulic pump 17. Two output terminals of the two-way hydraulic pump 17 are connected to a rod chamber and a rodless chamber of the single rod hydraulic cylinder 11 respectively through the hydraulic pipeline 12. The two output terminals of the two-way hydraulic pump 17 are in parallel with two overflow valves 15 which are reverse installed; The accumulator 13 is divided into three ways, the first way is connected to the rod chamber side of the single rod hydraulic cylinder 11, the second way is connected to a quick connector 14, and the third way is connected to the first pressure sensor 6, the two output terminals of the two-way hydraulic pump 17 are connected to the second pressure sensor 6 and the third pressure sensor 6. The servo motor 16 is connected to the rotation speed sensor 5. The rotation speed sensor 5, the built-in displacement sensor 7, the servo motor driver 4, and three pressure sensors 6 are respectively connected to the control computer 1 via electrical connection wiring 8. The movable pulley 9 is connected to the piston rod of the single rod hydraulic cylinder 11. The static pulley 10 is connected to the bottom of the single rod hydraulic cylinder 11. The static pulley 10 is located at the same axis as the movable pulley 9. The movable pulley 9 and the static pulley 10 are connected to the crane lifting wire rope. The built-in displacement sensor 7 is installed in the single rod hydraulic cylinder 11.

(10) The servo motor 16, the two-way hydraulic pump 17, the single rod hydraulic cylinder 11, the accumulator 13, the overflow valve 15, the quick connector 14, the three pressure sensors 6, the rotation speed sensor 5, the built-in displacement sensor 7 and the two Pilot operated check valve 18 are integrated into an autonomous system. The system doesn't need any hydraulic oil source, reduces the number of components and the volume of devices. After being connected by the electrical connection wiring, the control computer 1 gives the command signal and the system will start to work.

(11) The working principle of the offshore crane heave compensation control system using visual ranging according to the present invention is as follows:

(12) The control computer 1 is using as a controller. The industrial camera 2 using visual ranging detects the three-dimensional position information of the supply vessel. The direct pump control electro-hydraulic heave compensation device 3 is driven by the servo motor driver 4. As the executing device of the system, the rotation speed sensor 5, the three pressure sensors 6 and the built-in displacement sensor 7 collect the operating parameters of the direct pump control electro-hydraulic heave compensation device 3 and feed them back to the control system 1, as to achieve a closed-loop control of the direct pump control electro-hydraulic heave compensation device 3 in order to achieve loading up and down the cargo from the supply vessel by the offshore crane.

(13) During the up stage, the industrial camera 2 detects the position of heave motion of vessel using visual ranging, the velocity and the accelerated velocity of the supply vessel is calculated by the control computer 1. The servo motor driver 4 drive the direct pump control electro-hydraulic heave compensation device 3 adds the movement of supply vessel with the same direction and amplitude to the offshore crane, in order to find the right time to loading up, avoiding impact load to the wire rope during the up stage.

(14) During the down stage, the industrial camera 2 detects the position of heave motion of vessel using visual ranging, the velocity and the accelerated velocity of the supply vessel is calculated by the control computer 1. The servo motor driver 4 drive the direct pump control electro-hydraulic heave compensation device 3 adds the movement of supply vessel with the same direction and amplitude to the offshore crane, in order to load down the cargo to the supply vessel with the setting relative speed and find the right time to loading down to the supply vessel stably.

Embodiment 2

(15) The present invention provides a direct pump control electro-hydraulic heave compensation device of the offshore crane heave compensation control system using visual ranging. The direct pump control electro-hydraulic heave compensation device 3 is used as an executing device of the offshore crane heave compensation control system. The direct pump control electro-hydraulic heave compensation device 3 includes a servo motor driver 4, a servo motor 16, a two-way hydraulic pump 17, an accumulator 13, a quick connector 14, two overflow valves 15, a single rod hydraulic cylinder 11, a movable pulley 9, a static pulley 10, at least three pressure sensors 6, a rotation speed sensor 5, and a displacement sensor 7. The servo motor driver 4 drives the servo motor 16 to rotate the two-way hydraulic pump 17. Two output terminals of the two-way hydraulic pump 17 are connected to a rod chamber and a rodless chamber of the single rod hydraulic cylinder 11 respectively through the hydraulic pipeline 12. The two output terminals of the two-way hydraulic pump 17 are in parallel with two overflow valves 15 which are reverse installed. The servo motor 16 is connected to the rotation speed sensor 5. The rotation speed sensor 5, the built-in displacement sensor 7, the servo motor driver 4, and three pressure sensors 6 are respectively connected to the control computer 1 via electrical connection wiring 8. The movable pulley 9 is connected to the piston rod of the single rod hydraulic cylinder 11. The static pulley 10 is connected to the bottom of the single rod hydraulic cylinder 11. The static pulley 10 is located at the same axis as the movable pulley 9. The movable pulley 9 and the static pulley 10 are connected to the crane lifting wire rope. The built-in displacement sensor 7 is installed in the single rod hydraulic cylinder 11.

(16) The servo motor driver 4, the servo motor 16, the two-way hydraulic pump 17, the accumulator 13, the quick connector 14, the two overflow valves 15, the single rod hydraulic cylinder 11, the movable pulley 9, the static pulley 10, at least the three pressure sensors 6, the rotation speed sensor 5, the built-in displacement sensor 7 are integrated into an autonomous system. The system doesn't need any hydraulic oil source, reduces the number of components and the volume of devices. After being connected by the electrical connection wiring, the control computer 1 gives the command signal and the system will start to work.

(17) The movable pulley 9, the piston rod of the single rod hydraulic cylinder 11 and the static pulley 10 of the direct pump control electro-hydraulic heave compensation device 3 are located at the same axis.

(18) Referring to FIG. 2 and FIG. 3, the first way of the accumulator 13 of the direct pump control electro-hydraulic heave compensation device 3 is connected to one output terminal of two pilot operated check valve 18 which are reverse installed, the other output terminal of two pilot operated check valve 18 which are reverse installed is in parallel with two output terminals of the two-way hydraulic pump 17.

(19) The movable pulley 9, the piston rod of the single rod hydraulic cylinder 11 and the static pulley 10 are located at the same axis.

(20) The two-way hydraulic pump 17, driven by the servo motor 16, performs the closed-loop control on the servo motor via the control computer 1, the servo motor driver 4, and the rotation speed sensor 5. The single rod hydraulic cylinder 11 is directly driven by the two-way hydraulic pump 17. By adjusting the rotation speed and direction of the servo motor 16, the direction of the flow of the two-way hydraulic pump 17 are controlled respectively, thereby driving the piston rod of the single rod hydraulic cylinder 11 to extend or retract.

(21) The accumulator 13 compensate for the difference in flow caused by the unequal area difference between the two sides of the piston of the single rod hydraulic cylinder 11, and recovers energy. The quick connector 14 fills the oil to the accumulator 13 during inspection, as to supplement the oil loss and replace the waste oil. The two overflow valves 15 prevent the system from overpressure.

(22) The rotation speed sensor 5, the three pressure sensors 6 and the built-in displacement sensor 7 collect the operating parameters of the direct pump control electro-hydraulic heave compensation device 3 and feed back to the control computer 1, as to control the closed-loop motion of the direct pump control electro-hydraulic heave compensation device 3.

(23) The single rod hydraulic cylinder 11 is fixed to the base of the offshore crane. The movable pulley 9 is connected to the piston rod of a single rod hydraulic cylinder 11. The static pulley 10 is connected to the bottom of the single rod hydraulic cylinder 11, and is at the same axis as the movable pulley 9. The movable pulley 9 and the static pulley 10 are connected to the offshore crane with the wire rope.

Embodiment 3

(24) Referring to FIG. 3, this is the second embodiment of the direct pump control electro-hydraulic heave compensation device 3 in the present invention. It includes a control computer 1, a servo motor driver 4, a servo motor 16, a two-way hydraulic pump 17, an accumulator 13, a quick connector 14, two overflow valves 15, a single rod hydraulic cylinder 11, a movable pulley 9, a static pulley 10, three pressure sensors 6, a rotation speed sensor 5, a displacement sensor 7, a hydraulic pipeline 12, electrical connection wiring 8 and two pilot operated check valves 18. The basic principle is the same as that in the embodiment 2 shown in FIG. 2. The direct pump control electro-hydraulic heave compensation device 3 can bear the negative load by two pilot operated check valve 18. The negative load means that the load drives the piston rod of the hydraulic cylinder to move. In FIG. 3, the negative load means that the piston rod of the single rod hydraulic cylinder 11 is pulled out by the external force. This working condition will not happen under the installation location as shown in FIG. 1 and FIG. 4. This structure which can bear the negative load, can guarantee the safety of the direct pump control electro-hydraulic heave compensation device 3 in the case of overload, can make the direct pump control electro-hydraulic heave compensation device 3 more flexible, and can increase the possibility of energy recovery.

Embodiment 4

(25) Referring to FIG. 4, it is a testbed of the offshore crane heave compensation control system using visual ranging. It includes a hydraulic oil source 19, a hydraulic control valve 20, a control handle 21, a hydraulic winch 22, a direct pump control electro-hydraulic heave compensation device 3, a control computer 1, an industrial camera 2, a rack 30, a simulated load 26, a 6-DOF platform 27, a control cabinet for power distribution 29 and a tension sensor 25.

(26) The direct pump control electro-hydraulic heave compensation device 3 and the industrial camera 2 are installed on the rack 30, one end of the wire rope 24 is connected with the simulated load 26 via the static pulley 10, movable pulley 9, tension sensor 25 of the direct pump control electro-hydraulic heave compensation device 3 with the simulated load 26, the other end of the wire rope 24 is connected with the hydraulic winch 22. The hydraulic control valve 20 respectively connects with the hydraulic oil source 19, the control handle 21 and the hydraulic winch 22, through the hydraulic pipeline 23. The simulated load 26 is loading up and down by the control handle 21. The simulated load 26 is placed on the 6-DOF platform 27, the 6-DOF platform 27 and the control cabinet for power distribution 29 combine together to simulate the vessel motion on the ocean. The control cabinet for power distribution 29, the sensor group 28, industrial camera 2 and servo motor driver 4 of the direct pump control electro-hydraulic heave compensation device 3 are connected with the control computer 1 respectively.

(27) Referring to FIG. 2, the direct pump control electro-hydraulic heave compensation device 3 includes a servo motor driver 4, a servo motor 16, a two-way hydraulic pump 17, an accumulator 13, a quick connector 14, two overflow valves 15, a single rod hydraulic cylinder 11, a movable pulley 9, a static pulley 10, at least three pressure sensors 6, a rotation speed sensor 5, and a displacement sensor 7. The servo motor driver 4 drives the servo motor 16 to rotate the two-way hydraulic pump 17. Two output terminals of the two-way hydraulic pump 17 are connected to a rod chamber and a rodless chamber of the single rod hydraulic cylinder 11 respectively through the hydraulic pipeline 12. The two output terminals of the two-way hydraulic pump 17 are in parallel with two overflow valves 15 which are reverse installed. The servo motor 16 is connected to the rotation speed sensor 5. The rotation speed sensor 5, the built-in displacement sensor 7, the servo motor driver 4, and three pressure sensors 6 are respectively connected to the control computer 1 via electrical connection wiring 8. The movable pulley 9 is connected to the piston rod of the single rod hydraulic cylinder 11. The static pulley 10 is connected to the bottom of the single rod hydraulic cylinder 11. The built-in displacement sensor 7 is installed in the single rod hydraulic cylinder 11.

(28) The servo motor driver 4, the servo motor 16, the two-way hydraulic pump 17, the accumulator 13, the quick connector 14, two overflow valves 15, single rod hydraulic cylinder 11, the movable pulley 9, the static pulley 10, at least three pressure sensors 6, the rotation speed sensor 5 and the built-in displacement sensor 7 are integrated into an autonomous device.

(29) The movable pulley 9, the piston rod of the single rod hydraulic cylinder 11 and the static pulley 10 of the direct pump control electro-hydraulic heave compensation device 3 are located at the same axis.

(30) the first way of the accumulator 13 of the direct pump control electro-hydraulic heave compensation device 3 is connected to one output terminal of two pilot operated check valve 18 which are reverse installed, the other output terminal of two pilot operated check valve 18 which are reverse installed is in parallel with two output terminals of the two-way hydraulic pump 17.

(31) The testbed simulates the motion of a vessel in the marine environment by a six-degree-of-freedom platform 27, which simulates a conventional offshore crane operation with a fixed rack 30, a hydraulic winch 22, a hydraulic oil source 19, a hydraulic control valve 20, a control handle 21, and a simulated load 26. The industrial cameral, heave compensator 3 are mounted on the fixed rack 30. The system is powered by the control cabinet of power distribution 29, controlled by the control computer 1. The control computer 1 is collected the data.

(32) The working principle of the testbed of the offshore crane heave compensation control system using visual ranging in the present invention is as follows:

(33) The testbed can simulate and test the offshore crane operation process, perform testing, data recording and processing an offshore crane heave compensation motion control system using visual ranging. The sensor group 28 includes a pressure sensor 6, a rotation speed sensor 5, a displacement sensor 7 and so on. It can record the hydraulic system operating parameters, the posture of the 6-DOF platform 27, the impact of wire rope 24, and the direct pump control electro-hydraulic heave compensation device 3 and send them to the control system 1. The control system 1 controls the hydraulic pressure system, 6-DOF platform 27, and the direct pump control electro-hydraulic heave compensation device 3. The offshore platform is a fixed offshore platform.

(34) The testbed of the offshore crane heave compensation motion control system using visual ranging can monitor the tension variation of the wire rope 24 connected between the simulated load 26 and the hydraulic winch 22 through the sensor group 28, as to study the control strategies and the impact comparison experiment of the offshore crane heave compensation motion control system using visual ranging.