A flexible and heavy-load six-DOF parallel robot for high-precision follow-up docking

Abstract

The present invention discloses a flexible heavy-load six-degree-of-freedom parallel robot for high-precision follow-up docking, which consists of three parts: a cylinder propulsion device, a six-degree-of-freedom parallel robot body and an adsorption-type hanging basket. Among them, the cylinder propulsion device mainly includes four groups of cylinders, which are connected to the adsorption-type hanging basket through fixed pulleys and steel wire ropes; the adsorption-type hanging basket mainly includes a hanging basket, an umbilical cord connector and a vacuum suction cup. The present invention compensates for the weight of the umbilical cord connector and the six-degree-of-freedom parallel robot body through the cylinder propulsion device, realizes the passive separation of the umbilical cord connector and the six-degree-of-freedom parallel robot body, effectively improves the six-degree-of-freedom parallel robot's responsiveness to high internal stress, and ensures high reliability during the fuel filling process; the present invention improves the system's tolerance threshold for contact impact, effectively avoiding the problem of unbalanced load or overload in the system. It has great application potential in realizing heavy-load six-degree-of-freedom parallel robots for high-precision docking tasks.

Description

Technical Field

[0001] The invention belongs to the field of six-degree-of-freedom parallel robot design, and in particular relates to a flexible heavy-load six-degree-of-freedom parallel robot for high-precision follow-up docking. Background Art

[0002] The heavy-duty six-degree-of-freedom parallel robot is mainly composed of a static platform, a dynamic platform and six groups of servo cylinders. The six groups of servo cylinders are arranged in parallel and connected to the static and dynamic platforms by ball joints, Hooke joints or universal joints. The parallel robot usually fixes the static platform on the base and controls the displacement and speed of the six groups of servo cylinders to fully and accurately control the position and posture of the rigid body in space. Since the six-degree-of-freedom parallel robot has the advantages of high load-bearing capacity, high rigidity, stable structure and high terminal flexibility, it is widely used in performance testing in any posture state, such as automatic fuel filling of launch vehicles, docking of rocket compartments and assembly of large aircraft and other high-precision docking and assembly tasks of aerospace products. In actual operation, the parallel robot is usually arranged in a side-standing suspension manner. After the visual measurement system feeds back the relative posture relationship of the key features of the docking components, the motion planner solves the spatial displacement velocity curve that each servo cylinder needs to track. By establishing a high-precision electro-hydraulic servo control strategy, it can be ensured that the six-degree-of-freedom parallel robot can achieve the task of actively tracking the target or reproducing the spatial posture.

[0003] In the actual process of automatic fuel filling of launch vehicles, the propellant needs to be filled into the fuel storage chamber through the umbilical connector. Generally, the umbilical connector is mounted on the parallel robot dynamic platform, and the position of the umbilical connector in space is adjusted in real time by controlling the displacement speed of multiple pairs of servo cylinders. Automatic fuel filling requires that the umbilical connector and the oil filling port remain connected for a period of time before being separated.

[0004] At present, the active follow-up method is mainly used in China to solve this problem. After the six-degree-of-freedom parallel robot completes docking and locking, the visual measurement system continues to monitor the swing of the rocket body and adjusts the terminal position of the parallel robot in real time, so that the umbilical connector follows the swing of the rocket body. However, at this time, the umbilical connector, the rocket body and the parallel robot are rigidly connected. Once the parallel robot cannot track the swing frequency and amplitude of the rocket body in time, it will cause the automatic fuel filling device and the rocket body to "tear" and there will be large internal stress. This will not only affect the connection reliability and sealing, leading to propellant leakage, but also cause excessive local stress in the parallel robot, resulting in the risk of servo cylinder breakage or platform overturning. In addition, the existing six-degree-of-freedom parallel robot adopts a side-standing suspension method. The weight of the six-degree-of-freedom parallel robot and the filling device is only balanced by the servo cylinder. There is no additional gravity compensation measure. The key load-bearing components such as the servo cylinder and the universal joint will be subject to a large additional bending moment. At the same time, because the rocket body is always in a low-frequency swing state due to wind load, in the absence of a buffer device, the contact impact force between the rocket body and the umbilical connector under the "dynamic-dynamic" docking condition is large. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a flexible heavy-load six-DOF parallel robot for high-precision follow-up docking.

[0006] The present invention first provides a flexible heavy-load six-degree-of-freedom parallel robot for high-precision follow-up docking, which is characterized by comprising: a cylinder propulsion device, a six-degree-of-freedom parallel robot body and an adsorption-type hanging basket;

[0007] The cylinder propulsion device comprises a gravity support frame and multiple transmission chains; each transmission chain comprises a ball-head type lifting ring 1, a cylinder, a gravity balance rope, a fixed pulley and a steel wire rope; the upper end of the steel wire rope is connected to the gravity balance rope through a ball joint, and the other side of the gravity balance rope is connected to the right end of the cylinder through the fixed pulley; the left end of the cylinder is connected to the ball-head type lifting ring 1 through a ball joint, and the ball-head type lifting ring 1 is connected to the gravity support frame through a threaded connection;

[0008] The six-degree-of-freedom parallel robot body at least includes a static platform, a dynamic platform, a metal bellows, and a flexible floating plate; the static platform and the dynamic platform are connected by six groups of static pressure support servo cylinders, the dynamic platform is connected to the metal bellows by bolts, the metal bellows is connected to the flexible floating plate by bolts, and the flexible floating plate is provided with positioning holes;

[0009] The adsorption type hanging basket comprises a vacuum suction cup, a second ball-head type lifting ring, a hanging basket, a positioning steel ball, an umbilical cord connector and a tapered pin; the vacuum suction cup and the positioning steel ball are fixedly connected to the same outer side of the hanging basket; the tapered pin is fixedly connected to the other outer side of the hanging basket opposite to the vacuum suction cup; the second ball-head type lifting ring is fixed to the top of the hanging basket by means of a threaded connection; the umbilical cord connector is fixed to the hanging basket by means of a bolt connection;

[0010] The second ball-head lifting ring is connected to the lower end of the wire rope in the form of a ball joint; the static platform of the six-degree-of-freedom parallel robot body is connected to the gravity support frame by bolts; the positioning holes on the flexible floating plate are connected with the positioning steel balls on the adsorption hanging basket, and the vacuum suction cup is adsorbed on the flexible floating plate.

[0011] An optional application scenario of the present invention is the automatic refueling of a launch vehicle, which requires the propellant to be filled into the fuel storage chamber from the rocket body oil filling port through an umbilical connector. Conical holes are arranged around the rocket body oil filling port, and their size is slightly larger than the conical pin, which can cooperate with the conical pin on the adsorption basket. This cooperation is a pre-assembly process for automatic fuel refueling, which mainly plays a role similar to that of a guide column and guide sleeve, and assists in the pre-docking of the umbilical connector and the oil filling port. The six-degree-of-freedom parallel robot still maintains a high-precision following motion state until the umbilical connector and the oil filling port are fully matched. At this time, the locking device inside the oil filling port is actuated to fix the relative position of the umbilical connector and the oil filling port. At this point, the automatic docking task of the umbilical connector is completed.

[0012] As a preferred embodiment of the present invention, there are four ball-head type lifting rings 2 distributed on the four corners of the top surface of the hanging basket, and there are four groups of transmission chains of the cylinder propulsion device, and the lower end of the steel wire rope of each group of transmission chains is respectively connected to a ball-head type lifting ring 2.

[0013] As a preferred embodiment of the present invention, the six-degree-of-freedom parallel robot body also includes a static platform universal joint, a hydrostatic support servo cylinder, and a dynamic platform universal joint; the static platform universal joint is connected to the static platform by bolts; the dynamic platform universal joint is connected to the dynamic platform by bolts; the left end of the hydrostatic support servo cylinder is connected to the static platform universal joint, and the right end of the hydrostatic support servo cylinder is connected to the dynamic platform universal joint; there are a total of six groups of transmission chains from the static platform universal joint to the dynamic platform universal joint, connecting the static platform with the dynamic platform.

[0014] As a preferred solution of the present invention, there are six metal bellows in total, two of which form a pair, and three pairs of metal bellows are distributed in a circle of 120°; the three pairs of metal bellows connect the flexible floating plate to the moving platform.

[0015] As a preferred solution of the present invention, the vacuum suction cups are fixedly connected to the hanging basket by welding. There are six pairs of vacuum suction cups, which are located on both sides of the surface where they are located and are symmetrically distributed.

[0016] The present invention also discloses a docking method based on the flexible heavy-load six-degree-of-freedom parallel robot, which comprises the following steps:

[0017] First, the reference position of the flexible heavy-load six-degree-of-freedom parallel robot is adjusted. At this time, the six-degree-of-freedom parallel robot body is in a fully retracted state, and this is used as the reference position; the ball-head type lifting ring 2 is connected to the lower end of the wire rope in the form of a ball joint; at this reference position, the initial length of each wire rope is adjusted to make the positioning steel ball coincide with the positioning hole of the flexible floating plate; at the same time, the gravity of the adsorption hanging basket is balanced by adjusting the rod chamber pressure of each group of cylinders; after completing the positioning and gravity balance, the vacuum suction cup is adsorbed on the flexible floating plate; after completing the system reference position adjustment, the system enters the high-precision motion control mode;

[0018] In the high-precision motion control mode, after the relative posture error of the docking target is obtained by the external visual measurement system, the spatial displacement velocity is decomposed into six pairs of hydrostatic support servo cylinders through the external motion planner, and the moving platform moves in the space with the desired posture; during the spatial movement, since the air inside the cylinder is compressible, the cylinder can adjust its pressure and stroke in real time according to the end posture of the six-degree-of-freedom parallel robot body, which compensates for the gravity well; at the same time, since the six-degree-of-freedom parallel robot body cannot meet the millimeter-level positioning error requirements of high-precision docking, a three-redundant flexible mechanism of cylinders, vacuum suction cups and metal bellows in parallel is used to compensate for the spatial six-degree-of-freedom posture, reducing the difficulty of docking; at the same time, the six-degree-of-freedom parallel robot can effectively absorb the tiny vibrations and contact shocks that occur during the docking process, thereby improving the stability of the system.

[0019] The flexible heavy-duty six-degree-of-freedom parallel robot for high-precision follow-up docking proposed in the present invention can be used as an arbitrary degree-of-freedom parallel mechanism for active follow-up docking assembly tasks. Automatic fuel filling is only a representative typical application scenario. Taking automatic fuel filling as an example, the external rocket body oil filling port and the umbilical connector are positioned and locked by a tapered pin, and then the system enters the active following mode; at this time, the external visual measurement system continues to monitor the swing of the rocket body and adjusts the end posture of the six-degree-of-freedom parallel robot body in real time to achieve the swing of the umbilical connector with the rocket body; in order to prevent the six-degree-of-freedom parallel robot body from being unable to match the frequency amplitude of the rocket body swinging during the following process, causing the umbilical connector to introduce excessive load, resulting in damage to the hydrostatic support servo cylinder, the static platform universal joint and the dynamic platform universal joint or the high-precision sensor element, the vacuum suction cup can be passively detached from the flexible floating plate, and at this time only the adsorption basket is attached to the rocket body, and its gravity is compensated by the cylinder propulsion device, and it will not produce a large force on the rocket body, thereby improving safety and reliability.

[0020] Compared with the prior art, the present invention utilizes a cylinder propulsion device to assist in docking, balancing the additional load caused by the cantilever beam-like structure under the side suspension of the docking device, and avoiding possible resonance shaking and local stress in the system. The present invention utilizes the compressibility of the cylinder, the buffering property of the metal bellows and the vacuum suction cup to add a flexible buffering function to the parallel robot, greatly reducing the contact impact under heavy-load docking, which is beneficial to protecting the high-precision docking device and reducing the difficulty of docking. In addition, the passive instantaneous detachment of the vacuum suction cup effectively improves the system's responsiveness to external loads, avoids fuel leakage and high internal stress problems in the active follow-up mode, and greatly improves the safety of the automatic fuel filling process. In summary, the present invention greatly improves the safety and stability of the heavy-load six-degree-of-freedom parallel robot, and provides great help for efficient and safe high-precision heavy-load docking and assembly tasks. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the structure of a flexible heavy-load six-DOF parallel robot for high-precision follow-up docking according to an implementation example;

[0022] Figure 2 A structural schematic diagram of a flexible heavy-load six-DOF parallel robot for high-precision follow-up docking according to an implementation example (front view perspective);

[0023] Figure 3 A schematic diagram of the structure of a cylinder propulsion device according to an implementation example;

[0024] Figure 4 A schematic diagram of the structure of a six-degree-of-freedom parallel robot body according to an implementation example;

[0025] Figure 5 It is a schematic diagram of the structure of an adsorption hanging basket according to an implementation example.

[0026] In the figure, 1-cylinder propulsion device, 2-six-degree-of-freedom parallel robot body, 3-adsorption type hanging basket, 101-gravity support frame, 102-ball head type lifting ring one, 103-cylinder, 104-gravity balance rope, 105-fixed pulley, 106-wire rope, 201-static platform, 202-static platform universal joint, 203-static pressure support servo cylinder, 204-dynamic platform universal joint, 205-dynamic platform, 206-metal bellows, 207-flexible floating plate, 301-vacuum suction cup, 302-ball head type lifting ring two, 303-hanging basket, 304-positioning steel ball, 305-umbilical cord connector, 306-taper pin. DETAILED DESCRIPTION

[0027] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0028] like Figure 1-5 As shown, the flexible heavy-load six-DOF parallel robot designed for high-precision follow-up docking in this embodiment is mainly composed of three parts: a cylinder propulsion device 1, a six-DOF parallel robot body 2 and an adsorption-type hanging basket 3.

[0029] like Figure 3 As shown, the cylinder propulsion device 1 includes a gravity support frame 101 and multiple transmission chains; each transmission chain includes a ball-head type lifting ring 102, a cylinder 103, a gravity balance rope 104, a fixed pulley 105 and a steel wire rope 106; the upper end of the steel wire rope 106 is connected to the gravity balance rope 104 through a ball joint, and the other side of the gravity balance rope 104 is connected to the right end of the cylinder 103 through the fixed pulley 105; the left end of the cylinder 103 is connected to the ball-head type lifting ring 102 through a ball joint, and the ball-head type lifting ring 102 is connected to the gravity support frame 101 through a threaded connection;

[0030] like Figure 4 As shown, the six-degree-of-freedom parallel robot body 2 at least includes a static platform 201, a dynamic platform 205, a metal bellows 206, and a flexible floating plate 207; the static platform 201 and the dynamic platform 205 are connected through six groups of static pressure support servo cylinders, the dynamic platform 205 is connected to the metal bellows 206 through bolts, the metal bellows 206 is connected to the flexible floating plate 207 through bolts, and the flexible floating plate 207 is provided with positioning holes;

[0031] like Figure 5 As shown, the adsorption type hanging basket 3 includes a vacuum suction cup 301, a second ball-head type lifting ring 302, a hanging basket 303, a positioning steel ball 304, an umbilical cord connector 305 and a tapered pin 306; the vacuum suction cup 301 and the positioning steel ball 304 are fixedly connected to the same outer side of the hanging basket 303; the tapered pin 306 is fixedly connected to the other outer side of the hanging basket 303 opposite to the vacuum suction cup 301; the second ball-head type lifting ring 302 is fixed to the top of the hanging basket 303 by threaded connection; the umbilical cord connector 305 is fixed to the hanging basket 303 by bolt connection; the vacuum suction cup 301 is fixedly connected to the hanging basket 303 by welding, and there are six pairs of vacuum suction cups 301, which are located on both sides of the surface where they are located and are symmetrically distributed;

[0032] The ball-head type lifting ring 2 302 is connected to the lower end of the wire rope 106 in the form of a ball joint; the static platform 201 of the six-degree-of-freedom parallel robot body 2 is connected to the gravity support frame 101 by bolts; the positioning hole on the flexible floating plate 207 is matched with the positioning steel ball 304 on the adsorption type hanging basket 3, and the vacuum suction cup 301 is adsorbed on the flexible floating plate 207.

[0033] like Figure 1-5As shown, as a preferred embodiment of the present invention, there are four ball-head type lifting rings 302 distributed on the four corners of the top surface of the hanging basket 303, and there are four groups of transmission chains of the cylinder propulsion device 1, and the lower end of the steel wire rope 106 of each group of transmission chains is respectively connected to a ball-head type lifting ring 302.

[0034] like Figure 3 As shown, in a preferred embodiment, the six-degree-of-freedom parallel robot body 2 also includes a static platform universal joint 202, a hydrostatic support servo cylinder 203, and a dynamic platform universal joint 204; the static platform universal joint 202 is connected to the static platform 201 by bolts; the dynamic platform universal joint 204 is connected to the dynamic platform 205 by bolts; the left end of the hydrostatic support servo cylinder 203 is connected to the static platform universal joint 202, and the right end of the hydrostatic support servo cylinder 203 is connected to the dynamic platform universal joint 204; there are a total of six groups of transmission chains from the static platform universal joint 202 to the dynamic platform universal joint 204, connecting the static platform 201 with the dynamic platform 205.

[0035] As a preferred solution of the present invention, there are six metal bellows 206 , two in a pair, and three pairs of metal bellows 206 are distributed in a circle of 120°; the three pairs of metal bellows 206 connect the flexible floating plate 207 to the moving platform 205 .

[0036] The flexible heavy-load six-degree-of-freedom parallel robot for high-precision follow-up docking proposed in the present invention can solve the contradictions mentioned in the prior art. The present invention can be understood as an automatic fuel filling solution that combines active follow-up with passive follow-up. The cylinder propulsion device mainly includes four groups of cylinders, which are connected to the adsorption-type hanging basket through fixed pulleys and wire ropes; the six-degree-of-freedom parallel robot body is composed of a static platform, a dynamic platform, six groups of servo cylinders, a metal bellows and a flexible floating plate; the adsorption-type hanging basket mainly includes a hanging basket, an umbilical cord connector and a vacuum suction cup.

[0037] The flexible heavy-duty six-degree-of-freedom parallel robot for high-precision follow-up docking proposed by the present invention aims at the problem of large internal stress in active follow-up docking. When the swing amplitude of the rocket body is large during the fuel filling process, the vacuum suction cup will be passively disengaged, and the system will be switched to passive follow-up mode. The six-degree-of-freedom parallel robot body will be disconnected from the umbilical cord connector to prevent the reduction of the tightness of the oil filling port and the excessive local stress of the structural parts due to the mismatch between its movement frequency and amplitude and the rocket body, effectively improving the safety of the system; for the unavoidable contact impact problem during the docking assembly process, the compressibility of the cylinder, the buffering of the vacuum suction cup and the metal bellows are used to achieve soft contact at the docking moment and reduce the impact force; for the risk of servo cylinder breakage or overturning of the six-degree-of-freedom parallel robot, the cylinder propulsion device is used to compensate for the weight of the six-degree-of-freedom parallel robot body and the umbilical cord connector during the docking process, reducing the negative impact of the additional bending moment and gravity on the key load-bearing components of the six-degree-of-freedom parallel robot during the docking process. At the same time, after the vacuum suction cup is passively detached, the cylinder propulsion device can also effectively compensate for the additional load introduced by the umbilical connector attached to the rocket body, effectively improving the safety and stability of the overall system and greatly reducing the safety hazards caused by heavy loads.

[0038] When in use, the flexible heavy-duty six-degree-of-freedom parallel robot first needs to adjust the reference position. At this time, the six-degree-of-freedom parallel robot body 2 is in a fully retracted state, and this is used as the reference position. The ball-head type lifting ring 2 302 is connected to the lower end of the wire rope 106 in the form of a ball joint. At this reference position, by adjusting the initial length of the four wire ropes 106, the positioning holes welded on the positioning steel ball 304 and the flexible floating plate 207 are made to coincide. At the same time, the gravity of the adsorption-type hanging basket 3 is balanced by adjusting the rod chamber pressure of the four groups of cylinders 103. After completing the positioning and gravity balance, the vacuum suction cup 301 is adsorbed on the flexible floating plate 207. After completing the system reference position adjustment, the system enters the high-precision motion control mode.

[0039] After the relative posture error of the docking target is obtained by the visual measurement system, the spatial displacement speed is decomposed into six pairs of hydrostatic support servo cylinders 203 through the motion planner, and the moving platform 205 moves in the space with the desired posture. During the spatial movement, since the air inside the cylinder 103 is compressible, that is, the cylinder 103 can adjust its pressure and stroke in real time according to the terminal posture of the six-degree-of-freedom parallel robot body 2, which compensates for gravity well. At the same time, since the six-degree-of-freedom parallel robot body 2 cannot meet the millimeter-level positioning error requirements of high-precision docking, the three-redundant flexible mechanism of the cylinder 103, the vacuum suction cup 301 and the metal bellows 206 in parallel is used to compensate for the spatial six-degree-of-freedom posture, reducing the difficulty of docking. At the same time, thanks to the three-redundant flexible mechanism, the six-degree-of-freedom parallel robot body 2 can effectively absorb the tiny vibrations and contact shocks that occur during the docking process, and improve the stability of the system.

[0040] In the application scenario of automatic fuel filling, the arrow body oil filling port and the umbilical connector 305 are positioned and locked by the tapered pin 306, and then the system enters the active following mode. At this time, the visual measurement system continues to monitor the swing of the arrow body and adjusts the terminal posture of the six-degree-of-freedom parallel robot body 2 in real time to achieve the swing of the umbilical connector 305 with the arrow body. In order to prevent the umbilical connector from introducing excessive load during the following process due to the inability of the six-degree-of-freedom parallel robot body 2 to match the frequency amplitude of the arrow body swing, resulting in damage to key load-bearing components or high-precision sensor elements such as the hydrostatic support servo cylinder 203, the static platform universal joint 202 and the dynamic platform universal joint 204. The vacuum suction cup 301 can be passively detached from the flexible floating plate 207. At this time, only the adsorption basket 3 is attached to the arrow body, and its gravity is compensated by the cylinder propulsion device 1, and it will not produce a large force on the arrow body, thereby improving safety and reliability.

[0041] The present invention utilizes a cylinder propulsion device to assist docking, balancing the additional load caused by the cantilever beam-like structure under the side suspension of the docking device, and avoiding possible resonance shaking and local stress in the system. The present invention utilizes the compressibility of the cylinder, the buffering property of the metal bellows and the vacuum suction cup to add a flexible buffering function to the parallel robot, greatly reducing the contact impact under heavy-load docking, which is beneficial to protecting the high-precision docking device and reducing the difficulty of docking. In addition, the passive instantaneous detachment of the vacuum suction cup effectively improves the system's responsiveness to external loads, avoids fuel leakage and high internal stress problems in the active follow-up mode, and greatly improves the safety of the automatic fuel filling process. In summary, the present invention greatly improves the safety and stability of the heavy-load six-degree-of-freedom parallel robot, and provides great help for efficient and safe high-precision heavy-load docking and assembly tasks.

[0042] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A high-precision follow-up docking method for a flexible heavy-load six-degree-of-freedom parallel robot, the flexible heavy-load six-degree-of-freedom parallel robot comprising: A cylinder propulsion device (1), a six-degree-of-freedom parallel robot body (2) and an adsorption-type hanging basket (3); The cylinder propulsion device (1) comprises a gravity support frame (101) and a plurality of transmission chains; each transmission chain comprises a ball-end type lifting ring (102), a cylinder (103), a gravity balance rope (104), a fixed pulley (105) and a steel wire rope (106); the upper end of the steel wire rope (106) is connected to the gravity balance rope (104) through a ball joint, and the other end of the gravity balance rope (104) is connected to the right end of the cylinder (103) through the fixed pulley (105); the left end of the cylinder (103) is connected to the ball-end type lifting ring (102) through a ball joint, and the ball-end type lifting ring (102) is connected to the gravity support frame (101) through a threaded connection; The six-degree-of-freedom parallel robot body (2) comprises at least a static platform (201), a dynamic platform (205), a metal bellows (206), and a flexible floating plate (207); the static platform (201) and the dynamic platform (205) are connected via six groups of static pressure support servo cylinders, the dynamic platform (205) and the metal bellows (206) are connected via bolts, the metal bellows (206) and the flexible floating plate (207) are connected via bolts, and a positioning hole is provided on the flexible floating plate (207); The adsorption type hanging basket (3) comprises a vacuum suction cup (301), a second ball-head type lifting ring (302), a hanging basket (303), a positioning steel ball (304), an umbilical cord connector (305) and a tapered pin (306); the vacuum suction cup (301) and the positioning steel ball (304) are fixedly connected to the same outer side of the hanging basket (303); the tapered pin (306) is fixedly connected to the other outer side of the hanging basket (303) opposite to the vacuum suction cup (301); the second ball-head type lifting ring (302) is fixed to the top of the hanging basket (303) by means of a threaded connection; and the umbilical cord connector (305) is fixed to the hanging basket (303) by means of a bolt connection. The second ball-head type lifting ring (302) is connected to the lower end of the steel wire rope (106) in the form of a ball joint; the static platform (201) of the six-degree-of-freedom parallel robot body (2) and the gravity support frame (101) are connected by bolts; the positioning hole on the flexible floating plate (207) is matched with the positioning steel ball (304) on the adsorption type hanging basket (3), and the vacuum suction cup (301) is adsorbed on the flexible floating plate (207); There are four ball-head type lifting rings (302) distributed at the four corners of the top surface of the hanging basket (303); there are four groups of transmission chains of the cylinder propulsion device (1); the lower end of the steel wire rope (106) of each group of transmission chains is connected to a ball-head type lifting ring (302); The six-degree-of-freedom parallel robot body (2) also includes a static platform universal joint (202), a hydrostatic support servo cylinder (203), and a dynamic platform universal joint (204); the static platform universal joint (202) is connected to the static platform (201) by bolts; the dynamic platform universal joint (204) is connected to the dynamic platform (205) by bolts; the left end of the hydrostatic support servo cylinder (203) is connected to the static platform universal joint (202), and the right end of the hydrostatic support servo cylinder (203) is connected to the dynamic platform universal joint (204); there are a total of six groups of transmission chains from the static platform universal joint (202) to the dynamic platform universal joint (204), which connect the static platform (201) and the dynamic platform (205); Characterized in that, the high-precision follow-up docking method comprises the following steps: First, the reference position of the flexible heavy-duty six-degree-of-freedom parallel robot is adjusted. At this time, the six-degree-of-freedom parallel robot body is in a fully retracted state, and this is used as the reference position; the ball-head type lifting ring 2 (302) is connected to the lower end of the wire rope (106) in the form of a ball joint; at this reference position, the initial length of each wire rope (106) is adjusted to make the positioning steel ball (304) coincide with the positioning hole of the flexible floating plate (207); at the same time, the gravity of the adsorption type hanging basket (3) is balanced by adjusting the rod chamber pressure of each group of cylinders (103); after completing the positioning and gravity balance, the vacuum suction cup (301) is adsorbed on the flexible floating plate (207); after completing the system reference position adjustment, the system enters the high-precision motion control mode; In the high-precision motion control mode, after the relative position error of the docking target is obtained by the external visual measurement system, the spatial displacement speed is decomposed into six pairs of static pressure support servo cylinders (203) through the external motion planner, and the moving platform (205) moves in the space with the desired position. During the spatial movement, since the air inside the cylinder (103) is compressible, the cylinder (103) can adjust its pressure and stroke in real time according to the end position of the six-degree-of-freedom parallel robot body (2), thereby compensating for gravity well. At the same time, since the six-degree-of-freedom parallel robot body (2) cannot meet the millimeter-level positioning error requirements of high-precision docking, a three-redundant flexible mechanism of the cylinder (103), the vacuum suction cup (301) and the metal bellows (206) in parallel is used to compensate for the spatial six-degree-of-freedom position, thereby reducing the difficulty of docking. At the same time, the six-degree-of-freedom parallel robot body (2) can effectively absorb the tiny vibrations and contact shocks that occur during the docking process, thereby improving the stability of the system.

2. The high-precision follow-up docking method of the flexible heavy-load six-degree-of-freedom parallel robot according to claim 1 is characterized in that: There are six metal bellows (206) in total, two of which form a pair, and three pairs of metal bellows (206) are distributed in a circle of 120 degrees; the three pairs of metal bellows (206) connect the flexible floating plate (207) to the moving platform (205).

3. The high-precision follow-up docking method of the flexible heavy-load six-degree-of-freedom parallel robot according to claim 1 is characterized in that: The vacuum suction cup (301) is fixedly connected to the hanging basket (303) in the form of welding. There are six pairs of vacuum suction cups (301) located on both sides of the surface where the vacuum suction cups (301) are located and are symmetrically distributed.

4. The high-precision follow-up docking method of the flexible heavy-load six-degree-of-freedom parallel robot according to claim 1, characterized in that: The method is used to realize automatic fuel filling, and the method also includes the following steps: The external rocket body oil filling port and the umbilical connector (305) are positioned and locked by a tapered pin (306), and then the system enters an active following mode; at this time, the external visual measurement system continues to monitor the swing of the rocket body and adjusts the end posture of the six-degree-of-freedom parallel robot body (2) in real time to achieve the umbilical connector (305) swinging with the rocket body; in order to prevent the umbilical connector from introducing an excessive load during the following process due to the six-degree-of-freedom parallel robot body (2) being unable to match the frequency amplitude of the rocket body swing, causing the static pressure support servo cylinder (203), the static platform universal joint (202) and the dynamic platform universal joint (204) or the high-precision sensor element to be damaged, the vacuum suction cup (301) and the flexible floating plate (207) are passively separated. At this time, only the suction basket (3) is attached to the rocket body, and its gravity is compensated by the cylinder propulsion device (1), and no large force is generated on the rocket body, thereby improving safety and reliability.

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