CN115106695B - A reconfigurable modular flexible-cable parallel robot for welding irregular workpieces - Google Patents

Abstract

The present invention discloses a reconfigurable modular flexible cable parallel robot for welding irregular workpieces, including a reconfigurable track unit, a plurality of support modules arranged at intervals are mounted on the reconfigurable track unit, a winding module and a mechanical arm support module are respectively installed on the support module through a sliding module, the winding module is two parallel arrangements of one above and one below, a mechanical arm module is installed on the mechanical arm support module, the mechanical arm module includes a hoisting mechanical arm module and a welding mechanical arm module, the hoisting mechanical arm module is hoisted with a cylinder hoisting module through two mechanical arm ropes, and a welding equipment module driven by two mechanical arm ropes is installed at the end of the welding equipment module. The present invention is mainly divided into a reconfigurable track, a welding module unit and a hoisting module unit, and through different combinations of the three modules, a reconfigurable modular flexible cable parallel drive operation is formed, so that the equipment can adapt to various irregular workpieces, thereby more accurately controlling the end.

Description

Reconfigurable modularized flexible cable parallel robot for welding irregular workpieces

Technical Field

The invention relates to the field of robots, in particular to a reconfigurable modularized flexible cable parallel robot for welding irregular workpieces.

Background

Robots, an important representative of the development of artificial intelligence technology, play an important role in both industry and life. The welding robot effectively improves production efficiency in engineering application, reduces labor intensity of workers, has good stability, but has the problems of air holes, welding deflection and the like in the welding process, is more outstanding in the performance of a large thin-plate welding piece, has larger general size, low rigidity and complex surface shape, and is often accompanied with factors influencing the surface quality of the welding piece such as abrasion, vibration and the like in the processing process.

The existing welding robots are joint type serial robots, commonly known as six-axis welding robots and seven-axis welding robots, but the working space is often limited, and particularly the flexibility is greatly reduced when the welding robots face large workpieces, the welding robots are more outstanding when the targets are irregular workpieces, and the working space is required to be expanded, so that the number of joints can only be increased or the length of the joints can be prolonged, the accumulated error of a mechanism can be further increased, and the precision of a welding equipment module is reduced.

Because of these drawbacks of serial and parallel robots, some existing industrial robots have appeared to employ parallel processing in order to expand their applicability industrially. For example, the Chinese patent application number 202111477007.9 discloses a prefabrication welding method for manufacturing pipe sections by modularization of chemical equipment, the mechanism integrally adopts a parallel connection mode, and each module is an independent serial mechanical arm, but the working space is smaller due to the fact that the mechanical arm occupies a larger space area. In machining irregularly shaped workpieces, conventional tandem robots are generally characterized, so some of the inventive patents add movable rails to the conventional tandem robots. For example, china patent number 202111125300.9, a welding device suitable for valve production and manufacture, and China patent number 202210020126.X, a positioning mechanism and a welding robot. The two patents are characterized in that circular tracks are matched with welding equipment on the basis of the traditional serial mechanical arms, and the flexibility of the equipment is enhanced by utilizing the movement of the welding equipment in the welding process, but the problem of smaller working space still exists due to the volume of the mechanical arms, and a certain accumulated error exists. So that some patents appear to complete the hoisting and welding process in parallel connection. For example, the invention patent with the application number of 201410090629.X is a modularized reconfigurable flexible cable parallel mechanism experiment platform, and the invention combines a circular track and a traditional flexible cable parallel mode, so that the working space is increased, but a single-side rope hoisting mode is adopted, the rigidity is lower, the experiment platform is generally used for traditional hoisting operation, and the application scene is limited.

In summary, the invention aims to improve the rigidity and the control precision of equipment while improving the working space of the equipment, so that the applicability of the equipment is wider, and the invention designs a reconfigurable modularized flexible cable parallel robot for welding irregular workpieces. The whole flexible cable parallel connection mode is adopted, so that the working space is increased, the flexibility of equipment is improved in the welding process, and the problem of low rigidity exists in the traditional flexible cable parallel connection structure, so that the rigidity of the system is improved in the rigid-flexible coupling mode of the mechanical arm module. The welding module unit adopts two ropes to drive, wherein the winding module is designed to enable the ropes to be connected on the connecting shaft according to a specific winding mode, and interference between the driving ropes and the workpiece is effectively avoided. The angle of the mechanical arm module is changed, the single-side hoisting or parallel connection two configurations can be adjusted, and meanwhile, the variable stiffness module is designed, so that the tension change of the rope can be effectively controlled.

When irregular welding pieces are processed, the welding mode adopts layer-by-layer welding, generally from bottom to top, the hoisting module unit is used for fixing the welded pieces, the welding module unit is used for welding workpieces, the gear set is used for controlling the angle of the mechanical arm module, the rope is used for controlling the angle of the welding gun, the welding gun can be freely controlled to reach a preset position by matching with the reconfigurable track, and the welding requirements of irregular workpieces and complex curved surfaces are met.

Disclosure of Invention

The invention aims to overcome the defects and the shortcomings of the prior art, and provides a reconfigurable modularized flexible cable parallel robot for welding irregular workpieces, which is characterized in that the working space of the robot is increased by adopting a parallel connection mode as a whole, the rigidity of the whole structure is increased by a rigid-flexible coupling mode, meanwhile, the tension of a rope is controlled by matching with a rigidity-changing module, and the flexibility and the high efficiency of the robot are increased by adopting a reconfigurable modularized mode, so that the robot can adapt to various irregular workpieces, and the winding module can also avoid the interference of the rope and the interference between the rope and the workpieces.

In order to achieve the above purpose, the present invention provides the following technical solutions:

The reconfigurable modularized flexible cable parallel robot comprises a reconfigurable track unit, a support module, a sliding module, a winding module, a mechanical arm support module, a mechanical arm module, a hoisting mechanical arm module, a welding mechanical arm module, a cylindrical hoisting module, mechanical arm ropes and a welding equipment module, wherein the reconfigurable track unit is provided with a plurality of support modules which are arranged at intervals, the winding module and the mechanical arm support module are respectively arranged on the support modules in parallel through the sliding module, the mechanical arm modules are arranged on the mechanical arm support module one by one, the mechanical arm module comprises a hoisting mechanical arm module and a welding mechanical arm module, the hoisting mechanical arm module is provided with a cylindrical hoisting module for installing a workpiece in a hoisting mode through two mechanical arm ropes, and the end part of the welding equipment module is provided with the welding equipment module which is driven by two mechanical arm ropes;

the driving process of the hoisting mechanical arm module comprises the steps that one mechanical arm rope is led out from a lower winding module, guided by a winding pulley block on an upper winding module, bypasses a mechanical arm supporting module, then passes through the hoisting mechanical arm module, extends out from the front end part of the hoisting mechanical arm module and is connected to a lifting ring pulley module at the upper end of a cylinder hoisting module, and the other mechanical arm rope is led out from the upper winding module, bypasses the mechanical arm supporting module, passes through the hoisting mechanical arm module, and then extends out from the front end part of the hoisting mechanical arm module and is connected to a lifting ring pulley module at the lower end of the cylinder hoisting module;

the driving process of the welding mechanical arm module comprises the steps that one mechanical arm rope is led out from a lower winding module, guided by a winding pulley block on an upper winding module, bypasses a mechanical arm supporting module, sequentially penetrates through the hoisting mechanical arm module and extends out from the front end part of the hoisting mechanical arm module to be connected to a lifting ring pulley module at the upper end of the cylinder hoisting module, and the other mechanical arm rope is led out from an upper winding module, bypasses the mechanical arm supporting module, sequentially penetrates through the hoisting mechanical arm module and extends out from the front end part of the hoisting mechanical arm module to be connected to a lifting ring pulley module at the lower end of the cylinder hoisting module.

The reconfigurable track units are composed of different numbers of reconfigurable tracks, the reconfigurable tracks are made of sectional materials, adjacent reconfigurable tracks are connected through movable hinges, the reconfigurable track units in different shapes can be assembled according to requirements, the reconfigurable track units are triangular, quadrilateral, pentagonal or hexagonal, at least three sections of sectional materials with equal lengths and two movable hinges are formed, and the reconfigurable track units can be folded in the transportation and storage processes, so that the occupied space is greatly reduced, and the construction rapidity is improved.

The support module comprises a plurality of groups of support frames which are independently arranged, each support frame comprises two long sections which can be arranged in parallel, the two long sections are connected through short sections which are arranged at intervals up and down, two sides of each short section are respectively connected and fixed with the inner sides of the long sections through elastic fasteners, the elastic fasteners are adopted to connect, the portability of installation is greatly improved, threaded holes can be formed in one end of each long section, the long sections are connected through studs when installed on a reconfigurable track, the stability of the invention is enhanced, the bottom ends of the long sections are installed on a reconfigurable track unit through a disassembly and assembly module, sliding modules used for fixing a winding module and a mechanical arm support module are respectively installed on the front end faces of the long sections, and the sliding modules comprise linear sliding rails paved on the front end faces of the long sections, and sliding bases which are arranged at intervals are distributed on the linear sliding rails.

Through holes with the same interval are formed in the linear sliding rail and are used for being matched with the supporting frame to be fixed on the supporting frame. T-shaped bolts are connected with the square nuts in a matched mode through the linear sliding rails, so that the linear sliding rails are fixed on the long section bars of the supporting frame. The sliding base can freely slide on the linear slide rail, four through holes are formed in the periphery of the sliding base, a large through hole is formed in the center of the sliding base, and the sliding module is fixed on the linear slide rail by using the T-shaped bolt and the square nut in common operation. The four-side through holes are used for fixedly connecting the module on the sliding base, and in the invention, the winding module and the mechanical arm supporting module are fixedly connected on the sliding base through the bolts. The number of the sliding bases is added according to the requirements, and stability of the equipment is enhanced. The winding module and the mechanical arm supporting module are arranged on the sliding base, and a group of two sliding bases are used.

The winding module is used for providing driving force required by the welding equipment module and comprises a winding base, two winding end covers which are arranged in parallel are arranged on the winding base, a winding connecting shaft is rotatably arranged between the winding end covers, a plurality of winding rings which are arranged at intervals are sleeved on the winding connecting shaft, the winding rings are fixedly connected through a winding ring fixing shaft, a winding pulley block for supporting a rope is further arranged on the winding base, and the winding connecting shaft is driven by a motor at one side of the winding connecting shaft. The starting point of the rope is wound on the winding connecting shaft in the winding module, and the tail end of the rope is not required to be displaced to a great extent generally, so that the rope is wound on the right end of the winding connecting shaft, two winding pulleys pass through the mechanical arm module after passing through the winding ring, the winding ring is connected with the winding connecting shaft through bolts, and the rope can be prevented from being stacked in the winding process after passing through the winding ring. The winding pulley is arranged on the winding pulley seat and plays a role in guiding. According to the invention, two ropes are respectively controlled by adopting two winding modules on each modularized equipment, so that welding equipment modules are controlled, and the winding modules at the upper end of the modularized equipment are provided with more groups of pulleys and pulley seats compared with the winding modules at the lower end, so that the purpose of guiding the ropes led out from the winding modules at the lower end is achieved, and interference among the ropes, the winding modules and workpieces is avoided. The position of the winding module can be adjusted according to the requirements, and the winding module is fixed at the corresponding position before processing. The winding module is arranged on the supporting frame and can follow up the sliding module, so that shaking of the rope in the force transmission process is reduced, and the overall stability and accuracy of the mechanism are enhanced.

The mechanical arm support module comprises a mechanical arm support frame base, a mechanical arm support frame connecting shaft for installing the mechanical arm module is erected on the mechanical arm support frame base through a support, a mechanical arm support frame gear set is installed at one end of the mechanical arm support frame connecting shaft, and the mechanical arm support frame gear set is driven by a mechanical arm support frame motor at one side of the mechanical arm support frame gear set in a rotating mode. The mechanical arm support base is provided with four through holes at the periphery, the four through holes are used for being matched with the sliding base in the sliding module, the bolts and nuts are adopted to be installed on the sliding base, the mechanical arm support module is used for fixing the mechanical arm module, the through holes at one end of the mechanical arm module are matched with the mechanical arm support base connecting shaft in the mechanical arm support module, and the mechanical arm support base can rotate at a large angle, so that the rotation of the mechanical arm is realized. The mechanical arm supporting module can control the position of the mechanical arm, and then control the cable outlet point at the tail end of the mechanical arm.

The hoisting mechanical arm module comprises a mechanical arm outer frame used for supporting and guiding a mechanical arm rope, one end of the mechanical arm outer frame is fixedly arranged on a mechanical arm supporting frame connecting shaft of the mechanical arm supporting module, the other end of the mechanical arm outer frame is fixedly provided with a hemispherical pulley module, and a mechanical arm tensioning wheel and a rigidity changing module are arranged in the mechanical arm outer frame.

The hemispherical pulley module consists of a U-shaped hinge module and a hemispherical pulley, wherein the U-shaped hinge module consists of a large ring base, a middle ring base, a small ring base, a long connecting shaft and a short connecting shaft, the large ring base is connected with the middle ring base by the short connecting shaft, the middle ring base is connected with the small ring base by the long connecting shaft, an arc-shaped guide groove is formed in the middle of the hemispherical pulley, and through holes for a mechanical arm rope to pass through are formed in two sides of the corresponding position of the arc-shaped guide groove;

the rigidity-variable module comprises a rigidity-variable inner connecting ring, a rigidity-variable module ring outer frame and a rigidity-variable module ring inner frame unit are sleeved on the rigidity-variable inner connecting ring, inserting blocks are arranged on the inner side face of the rigidity-variable module ring inner frame unit, opening slots for inserting the inserting blocks are formed in the inner side of the rigidity-variable module ring outer frame, four rigidity-variable module ring inner frame units are uniformly distributed along the circumference of the rigidity-variable inner connecting ring, grooves are formed between the rigidity-variable module ring inner frame units to adapt to the tensile force of a mechanical arm rope, and the outer side of the rigidity-variable module ring inner frame unit is connected with the rigidity-variable module ring outer frame through springs. When the mechanical arm rope is pulled, the annular inner frame unit is extruded to move inwards along the diameter direction, and when the rope pulling force is reduced, the annular inner frame unit is restored to the original state under the action of the pulling force of the spring. The connecting ring is connected to a mechanical arm connecting shaft of the mechanical arm module.

The cylinder hoisting module comprises a cylinder frame, grooves are uniformly distributed in the outer circumferential direction of the cylinder frame and are arranged at intervals, a sliding rail is installed in the grooves, through holes for installing the sliding rail are formed in the grooves, a hoisting ring pulley module for connecting a mechanical arm rope is installed on the sliding rail, the hoisting ring pulley module is formed in a parallel opposite-pull mode, the hoisting ring pulley module consists of a hoisting ring base, a hoisting ring connecting shaft and a hoisting ring pulley, and a tail end connecting frame for installing a workpiece is installed at the upper end part in the cylinder frame. The cylindrical frame is designed to be cylindrical in order to accommodate the characteristics of the reconfigurable modularization, and when the reconfigurable track and the module unit are matched to form a form between three to six ropes, the cylindrical frame can be provided with a plurality of sliding tracks and hanging ring modules in a matching manner with the number of ropes. The sliding track is used for connecting the cylinder frame and the lifting ring module, and is provided with a plurality of through holes for fixing the sliding track on the cylinder frame and fixing the lifting ring module. One surface of the sliding track is provided with a rectangular groove for positioning the lifting ring module, so that the installation is convenient. The lifting ring module consists of a lifting ring base, a lifting ring connecting shaft and a lifting ring pulley. The bottom of rings base is equipped with the rectangle platform, is used for the cooperation the positive recess of slip track, fixed rings base. And the lifting ring pulley is used for connecting the mechanical arm rope. The number of the lifting ring modules is set according to the parallel connection mode, for general lifting and grabbing work, the sliding rails with different numbers are generally installed according to the number of ropes, one lifting ring module is installed on each sliding rail, and for working conditions requiring higher accuracy and rapider speed, the sliding rails with different numbers are installed, and two lifting ring modules are installed on each sliding rail to form a parallel connection mode. The connection points of the cylinder hoisting modules are arranged on the circumferential surface, the upper surface and the lower surface, and the positions of the connection points can be changed according to requirements.

The welding mechanical arm module comprises mechanical arm outer frames which are connected in a hinged mode and used for supporting and guiding mechanical arm ropes, mechanical arm tensioning wheels and stiffness changing modules are respectively arranged on the mechanical arm outer frames, the bottom end portion of one mechanical arm outer frame is fixedly arranged on a mechanical arm supporting frame connecting shaft of the mechanical arm supporting module, the upper end portion of the other mechanical arm outer frame is provided with a mechanical arm connecting shaft, a welding equipment module is arranged on the mechanical arm mounting shaft and comprises a welding equipment module base and a welding equipment module welding gun, and the welding equipment module is arranged on the mechanical arm and driven by the ropes, so that the mechanical arm outer frame can be used for processing workpieces with various irregular shapes and complex curved surfaces.

The application method of the reconfigurable modularized flexible cable parallel robot for welding irregular workpieces is characterized by comprising the following specific steps of:

(1) The system is initialized, firstly, position parameters of a workpiece to be welded are determined, the workpiece to be welded is placed at a fixed position, parameters of each module are adjusted, and the parameters are input into an upper computer of a control system;

(2) The upper computer determines the position of a main area of the working space according to the position parameters of the workpiece, a servo motor in the winding mechanism is started, a rope is adjusted to carry out tension balance according to the position form of the mechanism, and each sliding module, the mechanical arm supporting module, the spring and the welding equipment module are positioned at a stable position;

(3) In the movement process of the welding equipment module, a tension sensor, a rotation angle sensor and the like are used for collecting data and outputting the data to an upper computer, so that a balance mechanism is controlled to be adjusted along with the movement of the tail end, the rigidity of a spring is adapted, and the overall stability and accuracy of the mechanism are met;

(4) When a welding task is carried out, the hoisting module unit is used for fixing a welding piece, and the cylinder hoisting module at the tail end is used for adjusting the position of a hoisting point according to the welded piece and matched with a reconfigurable track so as to meet the requirements of supporting welding pieces with different shapes and complex curved surfaces and reduce the rigidity change of the welding piece;

(5) The welding equipment module controls the mechanical arm module and the welding gun to have 3 rotational degrees of freedom through two ropes, the ropes pass through the winding module and are connected to the tail end welding gun equipment module after passing through the mechanical arm module, the whole welding equipment module is welded layer by layer from bottom to top, the gear sets control the angle of the mechanical arm module, the ropes control the angle of the welding gun, the welding gun can be freely controlled to reach a preset position by matching with a reconfigurable track, and the irregular workpiece is welded after the track is set;

(6) When general hoisting operation is carried out, a parallel structure is adopted, a rope outlet point is positioned at the middle upper part of the integral mechanism, and different numbers of sub-modules are installed in cooperation with different shapes of the reconfigurable track to form hoisting structures with different forms such as three ropes, four ropes, five ropes, six ropes and the like;

(7) When the precision is high and the operation is fast, a parallel structure is still adopted, one part of the submodules adjusts the position of the cable outlet point to the middle lower part of the integral mechanism, and the other part of the submodules is kept at the middle upper part of the integral mechanism and mutually matched to form a double-pull structure, so that the operation rapidity of the integral mechanism is improved;

(8) After ensuring that the weldment is fully covered, the welding operation is completed and the system is initialized.

The flexible cable driving structure is used in the field of irregular workpiece welding, and the rigid-flexible coupling structure is realized through modularization, so that the welding process is rapidly carried out under the condition of ensuring stability. The reconfigurable track may improve flexibility of module movement over a typical track. The reconfigurable modularization can improve holistic working space, because early kinking part is installed in the bottom, control the end effector through the pulley, when the end effector removes the position nearer to the pulley, horizontal direction's force is too little, can not control the terminal well, but install kinking part on braced frame's slider, can make the atress of end effector horizontal direction more reasonable through the position of adjustment slider, thereby realize the accurate control to the end effector, use the arm module to cooperate with the variable stiffness module, in the increase flexibility, can also control flexible tension effectively.

The use scene of the mechanism is increased through the mode of assembling the reconfigurable track and the hoisting modularized units, the traditional flexible rope driving hoisting operation is adopted during the general hoisting operation, the number of ropes is determined according to the requirement, and the reconfigurable track and the supporting module are matched to form a multi-rope driving; the angle of the mechanical arm is adjusted during accurate operation and quick operation, and a pair-pull structure is formed by utilizing the cooperation of a plurality of support modules and the reconfigurable tracks. When the welding task is carried out, the welding module unit is added, the reconfigurable track and the hoisting module unit are matched, the pose of the end effector is controlled in real time, the working space of the equipment is increased, the accuracy and the efficiency of operation are improved, meanwhile, the mechanical arm module and the rigidity changing module are matched, the flexibility of the equipment is improved, the tension of a rope can be adjusted in real time, and the equipment can adapt to various irregular workpieces, so that the end is controlled accurately.

Compared with the prior art, the invention has the beneficial effects that:

1. The invention is mainly divided into a reconfigurable track, a welding module unit and a hoisting module unit, and the three modules are combined differently to form a reconfigurable modularized flexible cable parallel driving operation, so that the tail end can adapt to various irregular workpieces and the working space is increased. The hemispherical pulley module is arranged at the tail end of the hoisting module unit, and the rope can effectively adjust the angle change according to the tail end movement condition after passing through the device, so that the error caused by rope vibration is reduced. The ends of the welding module units may also be replaced with end effectors according to different scenarios.

2. The mechanical arm module adopts a rigid-flexible coupling structure, so that the rigidity of the system is increased, and meanwhile, the flexibility of the system is improved by adopting rope driving. For a more complex welding process, the hoisting module unit adjusts the angle of the mechanical arm to form a pull-to-pull mode to quickly and effectively control the position and the posture of the tail end, and the welding operation is completed by matching with welding equipment.

3. The rigidity-variable module can adjust the tension of the rope in real time to adapt to the pose change of the end effector, when the tension of the rope is increased, the spring of the rigidity-variable module is stretched, the inner connecting ring moves along the diameter direction, and when the tension of the rope is reduced, the spring and the inner connecting ring are restored to the initial state, so that the accuracy and the self-adaption capability of the equipment are greatly improved.

4. The winding module is designed with a winding ring device for fixing the extending or shortening path of the rope, and the rope passes through a preset track in the winding process, so that the influence of the stacking of the rope on the tension of the rope and the change of the tail end pose is reduced. The cylinder hoisting modules at the tail ends can be matched with different parallel connection modes, different numbers of linear slide rails and hoisting ring modules are installed, the track and the hoisting ring modules are arranged on the circumferential surface, the upper surface and the lower surface, and different connection points can be selected for debugging, so that the function of reconstructing the tail ends is realized.

Drawings

FIG. 1 is a schematic illustration of a reconfigurable modular flex parallel robot for irregular workpiece welding;

FIG. 2 (a) is a schematic diagram of a reconfigurable track-triangle of the invention;

FIG. 2 (b) is a schematic view of a reconfigurable track-quadrilateral of the invention;

FIG. 2 (c) is a schematic diagram of a reconfigurable track-pentagon of the invention;

FIG. 2 (d) is a schematic diagram of a reconfigurable track-hexagon of the invention;

FIG. 3 is a schematic diagram of an inventive hoist module unit;

FIG. 4 is a schematic view of an inventive support frame;

FIG. 5 is a schematic diagram of an inventive wire wrapping module;

FIG. 6 is a schematic view of a winding ring in the inventive winding module;

FIG. 6a is an enlarged view of a portion of the structure of FIG. 6;

FIG. 7 is a schematic diagram of an inventive robot support module;

FIG. 8 is a schematic diagram of an inventive hoist robot module;

FIG. 9 is a schematic diagram of an inventive hemispherical pulley module;

FIG. 10 is a schematic diagram of an inventive variable stiffness module;

FIG. 11 is a schematic view of an inventive cylinder lifting module;

FIG.11 a is a schematic view of a construction of a sling pulley module;

FIG. 12 is a schematic diagram of an inventive welding module unit;

fig. 13 is a schematic view of a welding robot module in the welding module unit of the invention.

Fig. 14 is a flow chart of the welding process of the present invention.

Reference numerals:

FIG. 1 shows a reconfigurable track-1, a disassembly module-2, a support module-3, a winding module-4, a mechanical arm support module-5, a mechanical arm module-6, a variable stiffness module-7, a welding equipment module-8 and a cylinder hoisting module-9;

FIG. 2 (a) - (d) living hinge-12, profile-11;

FIG. 3 shows a support module-3, a wire winding module-4, a mechanical arm support module-5, a mechanical arm module-6 and a variable stiffness module-7;

FIG. 4 shows an elastic fastener-31, a linear slide-32, a sliding base-33, a short section bar-34 and a long section bar-35;

FIG. 5 shows a wire winding base-41, a wire winding end cover-42, a wire winding pulley block-43, a wire winding motor-44, a wire winding synchronous belt-45, a wire winding ring-46, a wire winding ring fixing shaft-47 and a wire winding connecting shaft-48;

FIG. 6 shows a wrapping ring-46, ear hole-49;

FIG. 7 shows a robot support frame base-51, a robot support frame gear set-52, a robot support frame connecting shaft-53, and a robot support frame motor-54;

FIG. 8 is a diagram of an outer frame-61 of a mechanical arm, a tensioning wheel-62 of the mechanical arm, a hemispherical pulley module-63, a rope-64 of the mechanical arm and a rigidity-changing module-7;

FIG. 9, large ring base-631, medium ring base-632, small ring base-633, long connecting shaft-634, short connecting shaft-635, eye base-931, eye connecting shaft-932, eye connecting pulley 933;

FIG. 10 shows a variable stiffness modular annular outer frame-71, a variable stiffness modular annular inner frame unit-72, springs-73, a variable stiffness inner link annular ring-74;

FIG. 11 shows a cylindrical frame-91, a sliding rail-92, a sling pulley module-93, and an end connector-94;

FIG. 12 is a support module-3, a wire wrapping module-4, a mechanical arm support module-5, a mechanical arm module-6, a variable stiffness module-7, and a welding equipment module-8;

FIG. 13 includes an outer frame-61 of the mechanical arm, a tensioning wheel-62 of the mechanical arm, a rope-64 of the mechanical arm, a rigidity-changing module-7, and a connection of the mechanical arm

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

As shown in fig. 1, the reconfigurable modular flexible cable parallel robot for welding irregular workpieces mainly comprises a reconfigurable track-1, a disassembly module-2, a support module-3, a winding module-4, a mechanical arm support module-5, a mechanical arm module-6, a variable stiffness module-7, a welding equipment module-8 and a cylinder hoisting module-9, wherein:

As shown in fig. 2 (a) - (d), the reconfigurable track 1 is composed of an aluminum profile 11 and a movable hinge 12, each small unit is composed of 3 sections of aluminum profiles 11 and two movable hinges 12 which are connected, and can rotate arbitrarily, and the combination of different numbers and angles of units forms a track with various shapes, such as triangle, quadrangle, pentagon and hexagon. And splicing into different shapes according to requirements before installation. As shown in fig. 2 (a) - (d), respectively. The disassembly and assembly module consists of a section bar corner connecting piece and a T-shaped bolt and nut. When in operation, the dismounting module is used for connecting the reconfigurable track and the supporting frame. The quick assembly and disassembly between the reconfigurable track and the support frame can be realized by selecting the disassembly and assembly module, and the rigidity is higher, so that the whole structure is more stable.

As shown in fig. 3, the support module 3, the winding module 4, the mechanical arm support module 5, the mechanical arm module 6, the variable stiffness module 7 and the like form a hoisting module unit. The hoisting module unit is used as one of the modular equipment for general hoisting or grabbing tasks. The winding module 4 is arranged on the sliding base of the supporting module 3, the position of the winding module 4 is generally adjusted before processing and then is fixed by bolts, or when real-time control is needed, the winding module can be selected to be not fixed but to follow up according to the change of the terminal pose, so that the overall flexibility of the equipment is improved. The mechanical arm supporting module 5 is also arranged on the sliding base of the supporting module 3 and is connected by bolts. The mechanical arm module 6 is connected with the mechanical arm supporting module 5, a pair of gears are arranged on the mechanical arm supporting module 5, the gears are driven by a motor to rotate, and then the mechanical arm module 6 is driven to rotate for a certain angle, and the angles are freely combined according to a parallel connection mode. During general lifting and grabbing tasks, the mechanical arm module 6 is adjusted to be vertical to the ground or obliquely upwards at a certain angle, a plurality of lifting module units are matched to form a traditional parallel connection mode, a larger working space is provided, the mechanical arm module 6 can be adjusted to be obliquely downwards at a certain angle under the working condition of being required to be stable and fast, the lifting module units are matched to form a opposite pulling mode, the stability of the integral mechanism is improved, and the lifting module units drive ropes to enable the tail ends to finish translational and rotational freedom degree changes.

As shown in fig. 4, the support module 3 is composed of short and long profiles 34 and 35, elastic fasteners 31, linear slides 32 and sliding bases 33 in different numbers. Two long sections 35 in the support frame are taken as main bodies, and three short sections 34 with shorter sections are adopted in the middle to connect the two long sections. The support frame is mounted on the reconfigurable track 1 through a dismounting module, and the two sections of longer long section bars 35 are provided with sliding modules which can slide up and down as required and are fixed through bolts. The slide module consists of a linear slide 32 and a slide base 33. The linear slide rail 32 in the sliding module is fixed on the supporting module 3 through bolts, and the sliding base 33 is connected with the linear slide rail 32 and can slide up and down along the linear slide rail 32. 4 round holes are formed in two sides of the sliding base 33 and are used for being matched with the bottom plates in the winding module 4 and the mechanical arm supporting module 5, so that the winding module 4 and the mechanical arm supporting module 5 are fixed on the sliding base 33.

Above-mentioned reconfigurable track cooperation has the dismouting module for connecting braced frame, make the robot wholly fix subaerial, realize the quick installation of equipment, also can install the slip module as required, make braced frame can slide along reconfigurable track, can use the slip module when holistic rigidity requirement is not high and the required precision is higher. The invention takes welding equipment as the background, so the disassembly and assembly module is selected as the fixing device, thereby achieving the purpose of rapid disassembly and improving the stability of the whole equipment.

The disassembly and assembly module is used for connecting the support frame and the reconfigurable track. The disassembly and assembly module consists of an angle connecting piece, a T-shaped bolt and a square nut. The reconfigurable track is installed perpendicularly with braced frame, and fixed with dismouting module in braced frame's one end, and the angle connecting piece is equipped with two through-holes, and square nut is imported from the section bar is inside during the installation, and T type bolt passes through the through-hole and the square nut cooperation of angle connecting piece. The disassembly and assembly modules are symmetrically distributed and are respectively positioned at one ends of the two sections of the supporting frame. The reconfigurable tracks can be assembled into different shapes, but are all sections, so the same removable modules can be fixed on the reconfigurable tracks and connected to the support frame.

The support frame is used for providing support for the sliding module and the mechanical arm support module. Analysis is performed from separate vertical and horizontal directions, in which vertical movement is divided into two forms, one is a fixed slider, through which movement of the end effector is achieved by the control rope, and the other is a fixed rope, through which movement of the end effector is achieved by the lifting slider, since the winding module is mounted on the slider of the support frame. In the engineering practice of welding thin plates, the end effector is firstly enabled to reach a designated position through the lifting sliding block so as to achieve the purpose of rough adjustment, then the rope is controlled to achieve the purpose of fine adjustment through the change of the pose of the end effector, and therefore a step-by-step welding process is achieved, and the accuracy and the efficiency of the welding process can be improved. The active force or the passive force can be selectively applied in the horizontal direction, and the method is determined according to actual conditions. But always the force is decomposed in the horizontal and vertical directions, so that the resultant force in the vertical direction counteracts the gravity, and the resultant force of the ropes in the horizontal direction can control the motion state of the end effector according to the brought down of the applied force at a uniform speed or a non-uniform speed.

The sliding module is used for being matched with the supporting frame, and meanwhile, the supporting function is achieved. The sliding module consists of a linear sliding rail and a sliding base, wherein through holes with the same interval are arranged on the linear sliding rail and are used for being matched with the supporting frame to be fixed on the supporting frame. The T-shaped bolt is connected with the square nut in a matched manner through the linear slide rail, so that the linear slide rail is fixed on the long section bar of the supporting frame. The sliding base can freely slide on the linear slide rail, four through holes are formed in the periphery of the sliding base, a large through hole is formed in the center of the sliding base, and the sliding module is fixed on the linear slide rail by using T-shaped bolts and square nuts in common operation. The wire winding module and the mechanical arm supporting module are fixedly connected to the sliding base through bolts. The quantity of sliding base adds according to the demand, strengthens the stability of equipment. The winding module and the mechanical arm supporting module are arranged on the sliding base, and a group of two sliding bases are used.

As shown in fig. 5 and 6, the winding module 4 is composed of a winding base 41, a winding end cover 42, a winding pulley block 43, a winding motor 44, a winding timing belt 45, a winding ring 46, a winding ring fixing shaft 47, and a winding connecting shaft 48. The winding end cover 42 is fixed on the winding base 41, and the winding connecting shaft 48 is fixed on the winding end cover 42 through the winding bearing 47, so that the winding end cover can rotate for 360 degrees per se, and a large-angle rotation is realized. The rope passing through the winding ring 46 prevents the rope from being stacked on the winding connection shaft 48. Four wire winding ring fixing shafts are respectively connected with each wire winding ring and are fixed in through holes of the wire winding end cover 42, lug holes for threading ropes are uniformly distributed in the circumferential direction of the inner side of the wire winding ring, when the ropes are wound, firstly, the ropes are wound on a part of the right end of the intermediate shaft, then sequentially penetrate through the lug holes of the left wire winding ring clockwise or anticlockwise, the ropes are transmitted, and the winding direction of the ropes is limited. The winding motor 44 is fixed on the winding base 41, and is connected with the winding connecting shaft 48 through the winding synchronous belt 45, so that the synchronous movement of the winding motor 48 and the winding connecting shaft 48 is finally realized, and through holes are formed in the winding ring 46 and the outside of the winding connecting shaft, and the winding motor is connected with the winding connecting shaft through bolts during installation. Four round holes are formed in two sides of the winding base 41, and the four round holes are fixedly connected with the linear slide rail 32 in the sliding module through bolts. The winding pulley block is arranged on the winding end cover 42 and is used for supporting the rope and playing a role of guiding so as to avoid the interference of the rope led out by the winding module 4 at the lower end and the upper end.

As shown in fig. 7, the robot support module 5 is composed of a robot support frame base 51, a robot support frame gear set 52, a robot support frame connecting shaft 53, and a robot support frame motor 54. The mechanical arm support frame connecting shaft 53 is fixed on the mechanical arm support frame base 51 through a bearing, one of the gear sets is installed on the mechanical arm support frame connecting shaft 53, the other is installed on the mechanical arm support frame motor 54, the mechanical arm support frame motor 54 is fixed on the mechanical arm support frame base 51, and the gear sets are matched to realize one rotation degree of freedom of the mechanical arm. Four round holes are formed in two sides of the mechanical arm supporting frame base 51 and are fixed with the sliding base 33 in the sliding module through bolts.

As shown in fig. 8, the arm module 6 is composed of an arm outer frame 61, an arm tensioning wheel 62, an arm connecting shaft, an arm rope 64, and a variable stiffness module 65. The arm outer frame 61 in the arm module 6 is connected to the arm connecting shaft in the arm support module 6 through a bearing, and is cut off at the top for mounting the hemispherical pulley module 63. The arm connecting shaft is provided with an arm tensioning wheel 62, and an arm rope 64 and the variable stiffness module 7 can rotate around the arm connecting shaft. The arm connecting shafts 63 are provided in four, as shown in fig. 8, respectively. The mechanical arm rope 64 is wound on the mechanical arm connecting shaft in a specific winding mode, the variable stiffness module 7 is arranged on the mechanical arm connecting shaft in the middle, the mechanical arm rope 64 is connected to the end effector through the mechanical arm connecting shaft and the variable stiffness module 7, the pulling force of the mechanical arm rope 64 can be adaptively adjusted to meet the requirement of operation, and the stability and the high efficiency of the operation are realized.

As shown in fig. 9, the hemispherical pulley module 63 is composed of a U-shaped hinge module 631 and a hemispherical pulley 632, and the U-shaped hinge module is composed of a large ring base 6311, a medium ring base 6312, a small ring base 6313, a long connecting shaft 6314, and a short connecting shaft 6315. The large ring base 6311 and the medium ring base 6312 are connected by a short connecting shaft 6315, two short connecting shafts 6315 are mounted in the diameter direction, and the medium ring base 6312 and the small ring base 6313 are connected by a long connecting shaft 6314. The hemispherical pulley 632 is provided with through holes on both sides in the middle, and the top of the through holes is cut off and rounded. The arm cord 64 passes through the through hole and is wound around the cut-out circular surface. Hemispherical pulley 632 and U-shaped hinge module 631 fixed connection, large ring base 6311 passes through fixed connection with arm outer frame 61, and hemispherical pulley module 63 of being convenient for rotates certain angle, and the in-process hemispherical pulley 632 of being convenient for rope extension shortens the direction of arm rope 64.

The mechanical arm module is arranged on the sliding module, is matched with the sliding base in the sliding module to form a gear, so that the position of a rope outlet point can be adjusted at will, the mechanical arm module is vertically placed or obliquely upwards forms a certain angle in general hoisting operation, a plurality of modularized devices are utilized to cooperatively operate to form a classical parallel connection mode, the working space of the device is greatly increased, and the mechanical arm module can be adjusted to be obliquely downwards and obliquely upwards to form a certain angle and be symmetrically distributed in an environment needing higher precision and stability, so that a opposite pulling mode is formed, and the control precision is greatly improved. The four mechanical arm tensioning wheels are arranged in the middle of the outer frame of the mechanical arm, and the rope passes through the mechanical arm tensioning wheels in a splayed winding mode, so that the stability of the rope pulling force can be effectively improved. The tension wheel at the center position is provided with the rigidity-variable module, the rope can adaptively adjust the tension of the rope through the rigidity-variable module, and under the combined action of the mechanical arm tension wheel and the rigidity-variable module, the error of the tension of the rope can be controlled in a reasonable range. The end tensioner is used to transfer the pulling force of the rope.

As shown in fig. 10, the variable stiffness module 7 is composed of a variable stiffness module ring outer frame 71, a variable stiffness module ring inner frame unit 72, a spring 73, and a variable stiffness inner connection ring 74. The inner sides of the rigidity-changing module annular outer frame 71 and the rigidity-changing module annular inner frame unit 72 are arranged on the rigidity-changing inner connecting annular ring 74, the rigidity-changing module annular inner frame unit 72 is connected with the rigidity-changing module annular outer frame 71 through the rigidity-changing inner connecting annular ring 74, the rigidity-changing module annular inner frame unit 72 is provided with 4 grooves for adapting to the tensile force of the mechanical arm ropes 64, and the rigidity-changing module annular inner frame unit has a guiding function. The variable stiffness modular ring inner frame unit 72 is pressed to move radially inward when the arm cord 64 is pulled, and the variable stiffness modular ring inner frame unit 72 is restored under the tension of the spring when the tension of the arm cord 64 is reduced. The variable stiffness inner connecting ring 74 is connected to the arm connecting shaft of the arm module 6.

As shown in fig. 11, the cylindrical hoisting module 9 is composed of a cylindrical frame 91, a slide rail 92, and a hoist ring pulley module 93. The cylinder frame is used for providing support of the sliding rail 92 and the hanging ring module 93, grooves are formed in the periphery of the cylinder frame 91, and through holes are formed in the grooves and used for fixing the sliding rail 92. The cylindrical frame 91 is designed to be cylindrical in order to accommodate the characteristics of the reconfigurable modularization, and when the reconfigurable track and the module unit are mated to form a form between three to six ropes, the cylindrical frame 91 can be fitted with a plurality of slide tracks 92 and a hoist ring module 93 in accordance with the number of ropes. The slide rail 92 is used for connecting the cylindrical frame 92 and the eye module 93, and the slide rail 92 is provided with a plurality of through holes for fixing the slide rail 92 on the cylindrical frame 91 and for fixing the eye module 93. One surface of the sliding rail 92 is provided with a rectangular groove for positioning the lifting ring module 93, so that the installation is convenient. The hanging ring pulley module 93 consists of a hanging ring base 931, a hanging ring connecting shaft 932 and a hanging ring pulley 933. The bottom of the hanging ring base 931 is provided with a rectangular platform for matching with the groove on the front surface of the sliding rail 92 to fix the hanging ring base 931. The hoist ring pulley 833 is used to connect the arm cord 64. The number of the hanging ring modules 93 is set according to the parallel connection mode, for general hanging grabbing work, sliding rails 92 with different numbers are generally installed according to the number of ropes, one hanging ring module 93 is installed on each sliding rail 92, and for working conditions requiring higher accuracy and rapider speed, different numbers of sliding rails 92 are installed, two hanging ring modules 93 are installed on each sliding rail 92, and a counter-pulling parallel connection mode is formed.

As shown in fig. 12 and 13, the welding module unit is composed of a support module 3, a winding module 4, a mechanical arm support module 5, a mechanical arm module 6, a variable stiffness module 7 and a welding equipment module 8. The welding equipment module is arranged on the mechanical arm, and is driven by the rope, so that the characteristics of high load ratio and high flexibility can be realized, and workpieces with various irregular shapes and complex curved surfaces can be processed. The welding module is generally used for working conditions of collaborative welding operation and is matched with the hoisting module unit and the reconfigurable track 1. The winding module 4 is arranged on the sliding base of the supporting module 3, the position of the winding module 4 is generally adjusted before processing and then is fixed by bolts, or when real-time control is needed, the winding module 4 can be selected to be not fixed but to follow up according to the change of the terminal pose, so that the overall flexibility of the equipment is improved. The mechanical arm supporting module 5 is also arranged on the sliding base of the supporting module 3 and is connected by bolts.

The mechanical arm module 6 is connected with the mechanical arm supporting module 5, a pair of gears are arranged on the mechanical arm supporting module 5, the gears are driven by a motor to rotate, and then the mechanical arm module 6 is driven to rotate for a certain angle, and the angles are freely combined according to a parallel connection mode. When the welding task is carried out, the mechanical arm module 6 can be adjusted to be inclined downwards to form a certain angle, a plurality of hoisting module units are matched to form a split type, the stability of the whole mechanism is improved, the translation and rotation degrees of freedom of the tail end are changed under the action of the mechanical arm rope 64, and the welding module units are added on the basis to complete the collaborative operation. The welding arm module is different from the hoisting arm module in top, the top of the welding arm module is an arm connecting shaft 66, and the top of the hoisting arm module is a hemispherical pulley module 63. The welding equipment module controls the mechanical arm module and the welding gun to have 3 rotation degrees of freedom through two ropes, the ropes are connected to the tail end welding gun equipment module 8 through the winding module 4 after passing through the mechanical arm module 6, the whole welding equipment module is welded layer by layer from bottom to top, the gear sets control the angle of the mechanical arm module 6, the ropes control the angle of the welding gun 8, the welding gun 8 can be freely controlled to reach a preset position by being matched with the reconfigurable track 1, and the irregular workpiece is welded after the track is set. The end effector 8 is composed of an end effector base 81 and an end effector gun 82. The end effector base 81 is used for installing an end effector welding gun 82, and the end effector base 81 is connected with two mechanical arm ropes 64, so that the pose of the end effector welding gun 82 is changed under the action of different tensile forces of the mechanical arm ropes 64.

As can be seen from fig. 14, the welding steps of the reconfigurable modular parallel robot for welding irregular workpieces according to the present invention are as follows:

(1) The system is initialized, firstly, position parameters of a workpiece to be welded are determined, the workpiece to be welded is placed at a fixed position, the shape of the reconfigurable track 1 and parameters of the mechanical arm supporting module 5, the winding module 4 and the cylinder hoisting module 8 are adjusted, and the parameters are input into an upper computer of a control system;

(2) The upper computer determines the position of the main area of the working space according to the position parameters of the workpiece, a servo motor in the winding mechanism 4 is started, the ropes are adjusted to carry out tension balance according to the position form of the mechanism, and each sliding base 33, the mechanical arm module 6, the mechanical arm supporting module 5, the springs 73 and the end effector 9 are positioned at a stable position;

(3) In the movement process of the end effector 8, a tension sensor, a rotation angle sensor and the like are used for collecting data and outputting the data to an upper computer, so that a balance mechanism is controlled to be adjusted along with the movement of the end, and the rigidity of a spring 74 is adapted to meet the overall stability and accuracy of the mechanism;

(4) When the welding task is carried out, the hoisting module unit is used for fixing welding pieces, the cylinder hoisting module 9 at the tail end adjusts the position of a hoisting point according to the welded pieces and is matched with the reconfigurable track 1 so as to meet the requirements of supporting the welding pieces with different shapes and complex curved surfaces and reduce the rigidity change of the welding pieces.

(5) The welding equipment module controls the mechanical arm module and the welding gun to have 3 rotation degrees of freedom through two ropes, the ropes are connected to the tail end welding gun equipment module 8 through the winding module 4 after passing through the mechanical arm module 6, the whole welding equipment module is welded layer by layer from bottom to top, the gear sets control the angle of the mechanical arm module 6, the ropes control the angle of the welding gun 8, the welding gun 8 can be freely controlled to reach a preset position by being matched with the reconfigurable track 1, and the irregular workpiece is welded after the track is set.

(6) When general hoisting operation is carried out, a parallel structure is adopted, the cable outlet point is positioned at the middle upper part of the integral mechanism, and different numbers of sub-modules are installed in cooperation with different shapes of the reconfigurable track 1, so that hoisting structures with different forms such as three cables, four cables, five cables, six cables and the like are formed.

(7) When the precision is higher and the operation is fast, the parallel structure is still adopted, one part of the hoisting module units adjust the position of the cable outlet point to the middle lower part of the integral mechanism, and the other part of the hoisting module units are kept at the middle upper part of the integral mechanism and are mutually matched to form a double-pull structure, so that the operation rapidity of the integral mechanism is improved.

(8) After ensuring that the weldment is fully covered, the welding operation is completed and the system is initialized.

The reconfigurable track, the dismounting module, the supporting frame, the sliding module, the mechanical arm supporting module, the winding module, the rigidity changing module, the cylinder hoisting module, the welding equipment module, the driving rope and the motor are only the preferred modes of the invention, the track, the hoisting module unit, the welding module unit and the cylinder hoisting module realize the reconfigurable modularization, the rigidity-variable module adjusts rope tension, the winding module avoids interference of ropes, the working space, flexibility and high efficiency of equipment are integrally improved, the invention can be used in the fields of hoisting grabbing and irregular workpiece welding, and the tail end can be well controlled in real time to finish the welding process.

Although the present disclosure describes embodiments, not every embodiment is described in terms of a single embodiment, and such description is for clarity only, and one skilled in the art will recognize that the embodiments described in the disclosure as a whole may be combined appropriately to form other embodiments that will be apparent to those skilled in the art.

Therefore, the above description is not intended to limit the scope of the application, but rather should be construed in view of the appended claims.

Claims (7)

1. The reconfigurable modularized flexible cable parallel robot for welding irregular workpieces is characterized by comprising a reconfigurable track unit, a support module, a sliding module, a winding module, a mechanical arm support module, a mechanical arm module, a cylindrical hoisting module, mechanical arm ropes and a welding equipment module, wherein a plurality of support modules which are arranged at intervals are erected on the reconfigurable track unit, the winding module and the mechanical arm support module are respectively arranged on the support modules in parallel through the sliding module, the winding module is arranged in a two-by-one manner, the mechanical arm module is arranged on the mechanical arm support module, the mechanical arm module comprises a hoisting mechanical arm module and a welding mechanical arm module, the hoisting mechanical arm module is provided with the cylindrical hoisting module for installing the workpieces in a hoisting manner through two mechanical arm ropes, and the end part of the welding equipment module is provided with the welding equipment module which is driven by two mechanical arm ropes;

the driving process of the hoisting mechanical arm module comprises the steps that one mechanical arm rope is led out from a lower winding module, guided by a winding pulley block on an upper winding module, bypasses a mechanical arm supporting module, then passes through the hoisting mechanical arm module, extends out from the front end part of the hoisting mechanical arm module and is connected to a lifting ring pulley module at the upper end of a cylinder hoisting module, and the other mechanical arm rope is led out from the upper winding module, bypasses the mechanical arm supporting module, passes through the hoisting mechanical arm module, and then extends out from the front end part of the hoisting mechanical arm module and is connected to a lifting ring pulley module at the lower end of the cylinder hoisting module;

The driving process of the welding mechanical arm module comprises the steps that one mechanical arm rope is led out from a lower winding module, guided by a winding pulley block on an upper winding module, bypasses a mechanical arm supporting module, sequentially passes through the hoisting mechanical arm module, and extends out from the front end part of the hoisting mechanical arm module to be connected to a lifting ring pulley module at the upper end of the cylinder hoisting module;

the hoisting mechanical arm module comprises a mechanical arm outer frame for supporting and guiding a mechanical arm rope, one end of the mechanical arm outer frame is fixedly arranged on a mechanical arm supporting frame connecting shaft of the mechanical arm supporting module, the other end of the mechanical arm outer frame is fixedly provided with a hemispherical pulley module, and a mechanical arm tensioning wheel and a variable stiffness module are arranged in the mechanical arm outer frame;

The hemispherical pulley module consists of a U-shaped hinge module and a hemispherical pulley, wherein the U-shaped hinge module consists of a large ring base, a middle ring base, a small ring base, a long connecting shaft and a short connecting shaft, the large ring base is connected with the middle ring base by the short connecting shaft, the middle ring base is connected with the small ring base by the long connecting shaft, an arc-shaped guide groove is formed in the middle of the hemispherical pulley, and through holes for a mechanical arm rope to pass through are formed in two sides of the corresponding position of the arc-shaped guide groove;

The rigidity-variable module comprises a rigidity-variable inner connecting ring, a rigidity-variable module ring outer frame and a rigidity-variable module ring inner frame unit are sleeved on the rigidity-variable inner connecting ring, inserting blocks are arranged on the inner side face of the rigidity-variable module ring inner frame unit, opening slots for inserting the inserting blocks are formed in the inner side of the rigidity-variable module ring outer frame, four rigidity-variable module ring inner frame units are uniformly distributed along the circumference of the rigidity-variable inner connecting ring, grooves are formed between the rigidity-variable module ring inner frame units to adapt to the tensile force of a mechanical arm rope, and the outer side of the rigidity-variable module ring inner frame unit is connected with the rigidity-variable module ring outer frame through springs.

2. The reconfigurable modular parallel robot for welding irregular workpieces according to claim 1, wherein the reconfigurable track units are composed of unequal numbers of reconfigurable tracks, the reconfigurable tracks are made of sectional materials, adjacent reconfigurable tracks are connected through movable hinges, and the reconfigurable track units with different shapes can be assembled according to requirements, and are triangular, quadrangular, pentagonal or hexagonal.

3. The reconfigurable modular parallel robot for welding irregular workpieces according to claim 1, wherein the winding module comprises a winding base, two winding end covers which are arranged in parallel are arranged on the winding base, a winding connecting shaft is rotatably arranged between the winding end covers, a plurality of winding rings which are arranged at intervals are sleeved on the winding connecting shaft, the winding rings are fixedly connected through a winding ring fixing shaft, and a winding pulley block for supporting a rope is further arranged on the winding base, and the rotation of the winding connecting shaft is driven by a motor at one side of the winding pulley block.

4. The reconfigurable modular flex parallel robot for welding irregular workpieces of claim 1, wherein the robot support module comprises a robot support frame base, a robot support frame connecting shaft for installing the robot module is arranged on the robot support frame base through a support frame, a robot support frame gear set is installed at one end of the robot support frame connecting shaft, and rotation of the robot support frame gear set is driven by a robot support frame motor at one side of the robot support frame gear set.

5. The reconfigurable modular parallel robot for welding irregular workpieces according to claim 1, wherein the cylindrical hoisting module comprises a cylindrical frame, grooves which are arranged at intervals are uniformly distributed in the outer circumferential direction of the cylindrical frame, sliding tracks are arranged in the grooves, through holes for installing the sliding tracks are formed in the grooves, a hoisting ring pulley module for connecting a mechanical arm rope is arranged on the sliding tracks, the hoisting ring pulley module is formed in a parallel opposite-pull mode, the hoisting ring pulley module consists of a hoisting ring base, a hoisting ring connecting shaft and a hoisting ring pulley, and a tail end connecting frame for installing the workpieces is arranged at the upper end part in the cylindrical frame.

6. The reconfigurable modular parallel robot for welding irregular workpieces according to claim 1, wherein the welding robot arm module comprises a robot arm outer frame which is connected in a hinged manner and supports a guiding robot arm rope, the robot arm outer frame is respectively provided with a robot arm tensioning wheel and a variable stiffness module, the bottom end part of one robot arm outer frame is fixedly arranged on a robot arm support frame connecting shaft of the robot arm support module, the upper end part of the other robot arm outer frame is provided with a robot arm connecting shaft, the robot arm mounting shaft is provided with a welding equipment module, and the welding equipment module comprises a welding equipment module base and a welding equipment module welding gun.

7. A method of using a reconfigurable modular parallel robot for welding irregular workpieces according to any one of claims 1 to 6, characterized by the specific steps of:

(1) The system is initialized, firstly, position parameters of a workpiece to be welded are determined, the workpiece to be welded is placed at a fixed position, parameters of each module are adjusted, and the parameters are input into an upper computer of a control system;

(2) The upper computer determines the position of a main area of the working space according to the position parameters of the workpiece, a servo motor in the winding mechanism is started, a rope is adjusted to carry out tension balance according to the position form of the mechanism, and each sliding module, the mechanical arm supporting module, the spring and the welding equipment module are positioned at a stable position;

(3) The tension sensor and the rotation angle sensor acquire data and output the data to the upper computer in the movement process of the welding equipment module, so that the balance mechanism is controlled to adjust along with the movement of the tail end, and the rigidity of the spring is adapted to meet the overall stability and accuracy of the mechanism;

(4) When a welding task is carried out, the hoisting module unit is used for fixing a welding piece, and the cylinder hoisting module at the tail end is used for adjusting the position of a hoisting point according to the welded piece and matched with a reconfigurable track so as to meet the requirements of supporting welding pieces with different shapes and complex curved surfaces and reduce the rigidity change of the welding piece;

(5) The welding equipment module controls the mechanical arm module and the welding gun to have 3 rotational degrees of freedom through two ropes, the ropes pass through the winding module and are connected to the tail end welding gun equipment module after passing through the mechanical arm module, the whole welding equipment module is welded layer by layer from bottom to top, the gear sets control the angle of the mechanical arm module, the ropes control the angle of the welding gun, the welding gun can be freely controlled to reach a preset position by matching with a reconfigurable track, and the irregular workpiece is welded after the track is set;

(6) When general hoisting operation is carried out, a parallel structure is adopted, a rope outlet point is positioned at the middle upper part of the integral mechanism, and different numbers of sub-modules are installed in cooperation with different shapes of the reconfigurable track to form hoisting structures in different forms of three ropes, four ropes, five ropes or six ropes;

(7) When the precision is high and the operation is fast, a parallel structure is still adopted, one part of the submodules adjusts the position of the cable outlet point to the middle lower part of the integral mechanism, and the other part of the submodules is kept at the middle upper part of the integral mechanism and mutually matched to form a double-pull structure, so that the operation rapidity of the integral mechanism is improved;

(8) After ensuring that the weldment is fully covered, the welding operation is completed and the system is initialized.