CN114393566A

CN114393566A - Lightweight high-speed four-degree-of-freedom cable-driven parallel robot

Info

Publication number: CN114393566A
Application number: CN202210068017.5A
Authority: CN
Inventors: 邵珠峰; 段金昊; 张兆坤; 霍晔; 刘汉擎
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2022-01-20
Filing date: 2022-01-20
Publication date: 2022-04-26
Anticipated expiration: 2042-01-20
Also published as: CN114393566B

Abstract

The invention discloses a lightweight high-speed four-degree-of-freedom cable-driven parallel robot which comprises a static platform, a movable platform, a cable-driven branched chain and a central branched chain. The movable platform comprises an outer platform, an inner platform, a transmission mechanism and an actuator; the four groups of cable driving branched chains are respectively positioned on the front side, the rear side, the left side and the right side of the center of the static platform; parallel ropes of the left and right groups of rope driving branched chains are connected to the left and right sides of the outer platform, and parallel ropes of the front and rear groups of rope driving branched chains are connected to the front and rear sides of the inner platform; the central branched chain always tensions four groups of parallel ropes; when the four-freedom-degree SCARA robot works, the roller driving assemblies of the four cable driving branched chains control respective parallel cables, so that the movable platform has three-dimensional translational freedom, the parallel cables of the two cable driving branched chains which are oppositely arranged in front and back drive the inner platform, and the actuator has one-dimensional rotational freedom through the inner platform driving transmission mechanism, so that four-freedom-degree SCARA movement is realized. The invention has the advantages of light weight, high movement efficiency and the like.

Description

Lightweight high-speed four-degree-of-freedom cable-driven parallel robot

Technical Field

The invention relates to the technical field of parallel robots, in particular to a lightweight high-speed four-degree-of-freedom cable-driven parallel robot.

Background

In various industries such as food, medicine, new energy, logistics, 3C electronics and the like, a large number of robots for sorting, sorting and packaging products at high speed are required. The high-speed robot is an important component of an industrial robot, becomes core equipment for improving efficiency, reducing cost and improving quality in the field of sorting and packaging, and is large in demand and wide in demand.

The tail end of the high-speed robot is generally provided with different types of gripping tools or gripping hands according to different gripped objects, the robot body is required to have a space positioning function for the tail end, the tail end can realize three-degree-of-freedom space translation and one degree of freedom of rotation along a fixed direction axis so as to adjust the posture of the gripped objects, and finally, 4-degree-of-freedom SCARA motion is realized, namely translation motion in a three-dimensional space and rotation motion of an axis along the fixed direction are added.

The existing high-speed robots are rigid mechanisms and can be divided into two types, namely series robots and parallel robots according to different configurations. The tandem robot has the characteristics of large working space and good flexibility, but the moving branched chains of the tandem robot are stacked layer by layer, and the inertia of moving parts is large, so that the terminal speed and the acceleration of the tandem robot are low, and the power consumption is high. Parallel robot compares series connection robot and promotes in speed and efficiency to some extent, however to light-weighted, flexible and intelligent equipment development trend and the production demand that increasingly complicated and changeable, still there is the bottleneck of awaiting breakthrough in the aspect of the performance, the concrete expression is: (1) the moving branch chain adopts a rigid rod piece, so that the further reduction of the mass of a moving part and the further improvement of the moving efficiency are limited; (2) complex hinges such as spherical hinges and the like are used in a large number of the moving branched chains, so that the moving range of the moving platform is limited; (3) the drive unit requires the use of precision speed reducers with large reduction ratios and precision transmission components such as ball joints, which results in high cost.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, one object of the present invention is to provide a lightweight high-speed four-degree-of-freedom cable-driven parallel robot, which has the advantages of light weight, high motion efficiency, simple structure, large motion range and low cost, and can realize high-speed grabbing and picking.

The lightweight high-speed four-degree-of-freedom cable-driven parallel robot provided by the embodiment of the invention comprises:

a static platform;

the movable platform is positioned below the static platform at intervals and comprises an outer platform, an inner platform, a transmission mechanism and an actuator, the outer platform comprises an outer upper platform and an outer lower platform, the left side and the right side of the outer upper platform and the left side of the outer lower platform are fixedly connected, the inner platform and the transmission mechanism are both positioned between the outer upper platform and the outer lower platform, the transmission mechanism is respectively connected with the outer platform and the inner platform, and the actuator is positioned below the movable platform and is connected with the transmission mechanism;

the cable driving branched chains are provided with four groups, and the four groups of cable driving branched chains are respectively positioned on the front side, the rear side, the left side and the right side of the center of the static platform; each group of cable driving branched chains comprises a roller driving component, a pulley component and parallel ropes, wherein the roller driving component and the pulley component are installed on the static platform, the parallel ropes are wound on the roller driving component and are connected to the movable platform after being guided by the pulley component, the parallel ropes of two groups of cable driving branched chains which are oppositely arranged on the left and right sides are correspondingly connected to the left and right opposite sides of the outer platform, and the parallel ropes of two groups of cable driving branched chains which are oppositely arranged on the front and back sides are correspondingly connected to the front and back opposite sides of the inner platform;

two ends of the central branched chain are respectively connected to the center of the static platform and the center of the top of the movable platform and are used for tensioning four groups of parallel ropes all the time;

when the device works, the roller driving components of the four groups of cable driving branched chains respectively and correspondingly control the retraction and release of the parallel ropes, so that the movable platform has three-dimensional translational freedom, the inner platform is driven by the parallel ropes of the two groups of cable driving branched chains which are oppositely arranged in front and back, and the actuator has one-dimensional rotational freedom around the central axis of the actuator by driving the transmission mechanism by the inner platform, thereby realizing four-degree-of-freedom SCARA motion.

According to the lightweight high-speed four-degree-of-freedom cable-driven parallel robot disclosed by the embodiment of the invention, firstly, the inner platform is driven by the parallel cables, and then the actuator has one-dimensional rotational freedom degree around the central axis of the actuator through the inner platform driving transmission mechanism, and an additional driving unit is not required to be arranged on the movable platform to drive the actuator to rotate, so that the overall quality of the movable platform can be effectively reduced, and the parallel robot disclosed by the invention can realize the tasks of high-speed grabbing, sorting and the like at low cost and high efficiency. Secondly, the four groups of cable driving branched chains replace rigid rod piece moving branched chains in the prior art to drive the moving platform, on one hand, the mass of the parallel robot can be greatly reduced, and the parallel robot can easily realize high speed and acceleration, so that the moving efficiency of the robot is greatly improved, the load brought by the mass of the robot is small, and the energy consumption for driving the robot to move is small; on the other hand, each group of cable driving branched chains avoids complex hinges such as spherical hinges and the like which are used in large quantity by rigid rod piece moving branched chains in the prior art, and has low cost and simple structure. And thirdly, four groups of parallel ropes are tensioned all the time by arranging the central branched chain, so that the driving redundancy of a moving platform is avoided, the integral rigidity of the parallel robot is improved, the robot has better high-speed/high-acceleration performance, and high dynamic motion can be realized. Fourthly, the parallel robot has the advantages of strong load capacity and high precision of the rigid parallel mechanism and also has the advantages of low inertia and large working space of the cable driving mechanism by adopting the cable driving parallel mechanism.

According to some embodiments of the present invention, in each group of the cable driving branched chains, the number of the cables in the parallel cables is two, the number of the pulley assemblies is two, each of the two groups of the pulley assemblies has a cable exit point for leading out a single cable in the parallel cables, the movable platform has two cable connection points respectively connected to the two cables, and the two cable exit points and the two cable connection points are sequentially connected to form a parallelogram.

According to some embodiments of the invention, in each group of the rope-driving branched chains, the two ropes are always parallelly and synchronously reeled and reeled under the driving of the roller driving assembly.

According to some embodiments of the invention, a tension sensor is provided at each of the rope connection points, the tension sensor being used for rope force monitoring.

According to some embodiments of the present invention, the roller driving assembly includes a roller mounting seat fixedly mounted on an upper surface of the stationary platform, a roller rotatably supported on the roller mounting seat, one end of the parallel rope is wound on the roller, and a servo motor driving the roller to rotate forward and backward to change a length of the parallel rope between the pulley assembly and the movable platform.

According to some embodiments of the invention, the servo motor is equipped with an encoder.

According to some embodiments of the invention, the servo motor has a current sensor therein for rope force monitoring.

According to some embodiments of the invention, the pulley assembly comprises an upper pulley assembly and a lower pulley assembly; the upper pulley assembly is positioned above the static platform and comprises an upper pulley seat and an upper pulley; the upper pulley seat is fixed on the upper surface of the static platform, and the upper pulley is rotatably supported on the upper pulley seat; the lower pulley assembly is positioned below the static platform and comprises a sleeve, a rotating seat, two groove pulleys and two transverse cylinders; the sleeve penetrates through the static platform and is fixed with the static platform, and the top of the rotating seat is rotatably sleeved at the lower end of the sleeve; the axes of the two groove pulleys are positioned on the same horizontal plane, and the two groove pulleys are tangentially supported on the rotating seat side by side and can rotate; the two transverse cylinders are positioned below the two groove pulleys and at the same height, and the axes of the two transverse cylinders are perpendicular to the axes of the two groove pulleys; the two transverse cylinders are adjacently arranged side by side and rotatably supported on the rotating seat, and a slit is formed between the two transverse cylinders; and after being led out from the roller driving assembly, a single rope in the parallel ropes passes through the upper pulley, sequentially passes through the sleeve, the grooves corresponding to the two groove pulleys at the tangent positions and the slits in front of the two transverse cylinders downwards and is connected with the movable platform.

According to some embodiments of the invention, the sheave assembly further comprises an additional sheave assembly, a pressurized sheave assembly, and a pressure sensor; the additional pulley assembly is positioned above the static platform and comprises an additional pulley seat and an additional pulley, the additional pulley seat is fixed on the upper surface of the static platform, and the additional pulley is rotatably supported on the additional pulley seat; the pressure pulley assembly is positioned below the static platform and comprises a pressure pulley seat and a pressure pulley, the pressure pulley is rotatably supported on the pressure pulley seat, and the pressure sensor is fixed between the pressure pulley seat and the lower surface of the static platform; and a single rope in the parallel ropes is led out from the roller driving assembly, passes through the additional pulley, then passes through the static platform downwards, passes through the pressure-bearing pulley, then passes through the static platform upwards, and passes through the upper pulley.

According to some embodiments of the invention, the central branch comprises a tension unit, an upper end hinge and a lower end hinge; the upper end of the tensioning unit is connected with the center of the static platform through the upper end hinge, and the lower end of the tensioning unit is connected with the center of the outer upper platform through the lower end hinge.

According to some embodiments of the invention, the tensioning unit is a passive tensioning unit or an active tensioning unit.

According to some embodiments of the invention, the passive tensioning unit comprises a rigid rod and a first spring; the upper end hinge is composed of a first universal hinge and a first sliding pair, and is respectively an inner ring, a middle ring and an outer ring from inside to outside, a first rotating pair is arranged between the inner ring and the middle ring, a second rotating pair is arranged between the middle ring and the outer ring, the rotating axis of the first rotating pair is vertical to the rotating axis of the second rotating pair, so that the first universal hinge is formed, the outer ring is fixed in a central hole of the static platform, and a second shaft bearing is arranged on the inner ring; the upper end of the rigid rod passes through the second shaft bearing, so that a first moving pair is formed; the lower end hinge is a second universal hinge or a first spherical hinge, and the lower end of the rigid rod piece is connected with the lower end hinge; the first spring is always sleeved on the rigid rod piece in a compressed state, and two ends of the first spring are respectively connected with the upper end hinge and the lower end hinge.

According to some embodiments of the invention, the passive tensioning unit is a cylinder, the upper hinge is a third universal hinge or a second spherical hinge, the lower hinge is a fourth universal hinge or a third spherical hinge, the upper end of the cylinder is connected to the upper hinge, and the lower end of the cylinder is connected to the lower hinge.

According to some embodiments of the present invention, the active tensioning unit is an electric push rod, the upper end hinge is a fifth universal hinge or a fourth spherical hinge, the lower end hinge is a sixth universal hinge or a fifth spherical hinge, the upper end of the electric push rod is connected to the upper end hinge, and the lower end of the electric push rod is connected to the lower end hinge.

According to some embodiments of the invention, the active tensioning unit is a hydraulic cylinder, the upper end hinge is a seventh universal hinge or a sixth spherical hinge, the lower end hinge is an eighth universal hinge or a seventh spherical hinge, the upper end of the hydraulic cylinder is connected to the upper end hinge, and the lower end of the hydraulic cylinder is connected to the lower end hinge.

According to some embodiments of the invention, the transmission mechanism includes a screw rod and a screw nut, an upper end and a lower end of the screw rod are rotatably supported at a center of the outer upper platform and a center of the outer lower platform, respectively, the screw nut is disposed on the screw rod, the inner platform has a center hole, the inner platform is fixedly sleeved on an outer circumference of the screw nut through the center hole, and the actuator is coaxially fixed at the lower end of the screw rod.

According to some embodiments of the invention, the transmission mechanism further comprises a polished rod passing through the through hole of the inner platform, the polished rod is fixed at the upper end and the lower end on the outer upper platform and the outer lower platform respectively, and the second spring is sleeved on the polished rod in a compressed state and is located between the outer upper platform and the inner platform.

According to some embodiments of the invention, the transmission mechanism further comprises a second linear bearing mounted in the bore, the polished rod passing through the second linear bearing.

According to some embodiments of the invention, the transmission mechanism comprises a lateral support shaft, a lateral bevel gear, a rotation shaft, and a horizontal bevel gear; the transverse support shaft extends in the left-right direction between the outer upper platform and the outer lower platform, and the left end and the right end of the transverse support shaft are respectively fixed with the outer platform; the inner platform is rotatably supported on the transverse support shaft; the transverse bevel gear is arranged on the inner platform; the rotating shaft is vertically arranged and can be rotatably supported in the center of the outer lower platform and the transverse supporting shaft; the horizontal bevel gear is arranged on the rotating shaft and meshed with the transverse bevel gear; the actuator is coaxially fixed at the lower end of the rotating shaft.

According to some embodiments of the invention, there are two of the horizontal bevel gears, wherein one of the horizontal bevel gears is located above the lateral support shaft, and wherein the other horizontal bevel gear is located below the lateral support shaft; the horizontal bevel gears have two and be half section formula bevel gear, one of them half section formula bevel gear be located the left side of rotation axis and with two one in the horizontal bevel gear meshes, wherein another half section formula bevel gear be located the right side of rotation axis and with two another in the horizontal bevel gear meshes.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural view of a lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a roller driving assembly according to an embodiment of the present invention.

Fig. 3 is a schematic structural diagram of a pulley assembly according to an embodiment of the present invention.

Fig. 4 is an exploded view of the lower pulley assembly of fig. 3.

Fig. 5 is a schematic view of another sheave assembly according to an embodiment of the present invention.

FIG. 6 is a schematic structural view of the movable platform and the central branch chain in an embodiment of the present invention, wherein the central branch chain is shown to include a rigid rod and a first spring.

Fig. 7 is a schematic structural diagram of a first universal hinge in the embodiment of the present invention.

Fig. 8 is a schematic structural view of a movable platform and a central branch chain in another embodiment of the present invention, wherein the central branch chain is shown to include a cylinder.

FIG. 9 is a schematic structural view of a movable platform and a central branch chain according to yet another embodiment of the present invention, wherein the central branch chain is shown to include an electric push rod.

FIG. 10 is a schematic view of the structure of the movable platform and the central branch chain in yet another embodiment of the present invention, wherein the central branch chain is shown to include hydraulic cylinders.

Fig. 11 is a schematic structural diagram of a third universal hinge according to an embodiment of the present invention.

Fig. 12 is a schematic structural diagram of a movable platform according to an embodiment of the present invention.

Fig. 13 is a cross-sectional view of fig. 12.

Fig. 14 is a schematic structural diagram of another movable platform in the embodiment of the present invention.

Fig. 15 is a cross-sectional view of fig. 14.

Reference numerals:

lightweight high-speed four-degree-of-freedom cable-driven parallel robot 1000

Static platform 1

Moving platform 2

Outer platform 21, outer upper platform 211, outer lower platform 212, and center hole 221 of inner platform 22

Lead screw 231, lead screw nut 232, polished rod 233 and second spring 234 of transmission mechanism 23

Second linear bearing 235 laterally supports shaft 236 and laterally bevel gear 237 rotating shaft 238

Horizontal bevel gear 239 actuator 24

Cable driven branch 3

Drum driving assembly 31 drum mounting seat 311 drum 312 servo motor 313 reducer 314

Pulley block 3211 on pulley assembly 321 on pulley assembly 32 of coupler 315 encoder 316 pulley assembly 32

Upper pulley 3212 upper pulley shaft 3213 lower pulley assembly 322 sleeve 3221 rotates seat 3222

Horizontal barrel 3224 horizontal bearing 3225 and horizontal barrel shaft 3227 of groove pulley 3223

Additional Pulley Assembly 323 additional Pulley seat 3231 additional Pulley 3232 additional Pulley Axis 3233

Pressed pulley shaft 3243 of pressed pulley block 3241 pressed pulley 3242 pressed pulley base 324 pressed pulley

Parallel ropes 33 of pressure sensor 325

Central branch chain 4

The tensioning unit 41 rigid rod 411 first spring 412 upper end hinge 42 first universal hinge 421

Inner ring 4211, middle ring 4212, outer ring 4213, first revolute pair 4214, second revolute pair 4215

First sliding pair 422 and second shaft bearing 4221 lower end hinge 43 air cylinder 413

Third universal hinge 423 third inner ring 4231 third middle ring 4232 third outer ring 4233

Third revolute pair 4234 fourth revolute pair 4235 electric push rod 414 hydraulic cylinder 415

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

A lightweight high-speed four-degree-of-freedom cable-driven parallel robot 1000 according to an embodiment of the present invention will be described with reference to fig. 1 to 15.

As shown in fig. 1 to 15, a lightweight high-speed four-degree-of-freedom cable-driven parallel robot 1000 according to an embodiment of the present invention includes a stationary platform 1, a movable platform 2, a cable-driven branched chain 3, and a central branched chain 4. The movable platform 2 is arranged below the static platform 1 at intervals, the movable platform 2 comprises an outer platform 21, an inner platform 22, a transmission mechanism 23 and an actuator 24, the outer platform 21 comprises an outer upper platform 211 and an outer lower platform 212, the left side and the right side of the outer upper platform 211 and the left side of the outer lower platform 212 are fixedly connected, the inner platform 22 and the transmission mechanism 23 are both arranged between the outer upper platform 211 and the outer lower platform 212, the transmission mechanism 23 is respectively connected with the outer platform 21 and the inner platform 22, and the actuator 24 is arranged below the movable platform 2 and is connected with the transmission mechanism 23; four groups of cable driving branched chains 3 are arranged, and the four groups of cable driving branched chains 3 are respectively positioned on the front side, the rear side, the left side and the right side of the center of the static platform 1; each group of cable driving branched chains 3 comprises a roller driving component 31, a pulley component 32 and parallel ropes 33, the roller driving component 31 and the pulley component 32 are installed on the static platform 1, the parallel ropes 33 are wound on the roller driving component 31 and are connected to the movable platform 2 after being guided by the pulley component 32, wherein the parallel ropes 33 of the two groups of cable driving branched chains 3 which are oppositely arranged on the left and the right are correspondingly connected to the left and the right opposite sides of the outer platform 21, and the parallel ropes 33 of the two groups of cable driving branched chains 3 which are oppositely arranged on the front and the back are correspondingly connected to the front and the back opposite sides of the inner platform 22; two ends of the central branched chain 4 are respectively connected with the center of the static platform 1 and the top center of the movable platform 2 and are used for always tensioning four groups of parallel ropes 33; when the four-freedom-degree SCARA robot works, the roller driving assemblies 31 of the four cable driving branched chains 3 respectively and correspondingly control the retraction of the parallel ropes 33, so that the moving platform 2 has three-dimensional translational freedom, the inner platform 22 is driven by the parallel ropes 33 of the two cable driving branched chains 3 which are oppositely arranged in the front and back direction, and the actuator 24 has one-dimensional rotational freedom around the central axis of the actuator by the driving transmission mechanism 23 of the inner platform 22, so that the four-freedom-degree SCARA movement is realized.

Specifically, the static platform 1 is fixed relative to the movable platform 2 during use, and plays a role in fixing and installing, and provides an installation connection position and an interface for each functional component, for example, can provide an installation position and support for functional components such as the roller driving component 31 and the pulley component 32. Moving platform 2 has the interval to be located the below of quiet platform 1, moving platform 2 includes outer platform 21, interior platform 22, drive mechanism 23 and executor 24, outer platform 21 includes outer upper mounting plate 211 and outer lower platform 212, the left and right sides of outer upper mounting plate 211 and outer lower platform 212 is fixed continuous, interior platform 22 and drive mechanism 23 all are located between outer upper mounting plate 211 and the outer lower platform 212, and drive mechanism 23 links to each other with outer platform 21 and interior platform 22 respectively, executor 24 is located moving platform 2's below and links to each other with drive mechanism 23. It can be understood that the inner platform 22 is located between the outer upper platform 211 and the outer lower platform 212 to form the moving platform 2 with a layered structure, the inner platform 22 can move relative to the outer platform 21 to drive the transmission mechanism 23 to move, the transmission mechanism 23 converts the corresponding movement of the inner platform 22 into rotation around a vertical axis, so as to drive the actuator 24 connected to the transmission mechanism 23 to perform one-dimensional rotation around the central axis of the actuator 24, thereby realizing adjustment of the pose of the object on the actuator 24, that is, realizing planar rotational freedom through the moving platform 2 with a layered structure, without installing an additional driving unit on the moving platform 2, effectively reducing the moving mass, and realizing low-cost and high-efficiency robot equipment. The actuators 24 may be different types of gripping tools or gripping hands to implement the gripping function of the robot terminal.

The cable driving branched chains 3 are provided with four groups, the four groups of cable driving branched chains 3 are respectively positioned on the front side, the rear side, the left side and the right side of the center of the static platform 1, and specifically, in the figure 1, the four groups of cable driving branched chains 3 can be uniformly distributed in the circumference of the center of the static platform 1. Each group of cable driving branched chains 3 comprises a roller driving component 31, a pulley component 32 and a parallel rope 33, wherein the roller driving component 31 and the pulley component 32 are installed on the static platform 1, and the parallel rope 33 is wound on the roller driving component 31, guided by the pulley component 32 and then connected to the movable platform 2. Wherein, the roller driving assembly 31 is used for providing power to drive the parallel rope 33 wound on the roller driving assembly 31 to move so as to change the length of the parallel rope 33 between the pulley assembly 32 and the movable platform 2. Through the reasonable arrangement of the four sets of pulley assemblies 32, on one hand, the pulley assemblies 32 are used for guiding and reversing the parallel ropes 33, namely changing the extending direction of the parallel ropes 33, for example, as shown in fig. 1, so that the parallel ropes 33 penetrate through the static platform 1 downwards; on the other hand, when the roller driving assembly 31 adjusts the length of the parallel rope 33 between the pulley assembly 32 and the movable platform 2, it is ensured that the parallel rope 33 moves very smoothly. Four groups of parallel ropes 33 are used for controlling the dynamic platform 2, so that the dynamic platform 2 can realize three-degree-of-freedom spatial translation, and the three rotational degrees of freedom of the dynamic platform 2 are limited, namely, the outer platform 21 can perform three-dimensional translation relative to the static platform 1 but cannot rotate, and the motion of the dynamic platform 2 is more stable and efficient. Therefore, the parallel robot of the invention replaces the rigid rod 411 moving branched chain in the prior art with the four groups of cable driving branched chains 3 to drive the moving platform 2, on one hand, the mass of the parallel robot can be greatly reduced, so that the parallel robot can easily realize high speed and acceleration, thereby greatly improving the moving efficiency of the robot, and the load brought by the mass of the robot is small, and the energy consumption for driving the robot to move is also small; on the other hand, each group of cable driving branched chains 3 avoids complex hinges such as spherical hinges and the like which are used in large quantity by the rigid rod 411 moving branched chains in the prior art, and has simple structure and low cost.

The parallel ropes 33 of the two cable driving branched chains 3 which are oppositely arranged at the left and the right are correspondingly connected to the two opposite sides at the left and the right of the outer platform 21, and the parallel ropes 33 of the two cable driving branched chains 3 which are oppositely arranged at the front and the back are correspondingly connected to the two opposite sides at the front and the back of the inner platform 22 (as shown in figure 1). Therefore, when the actuator 24 needs to rotate, the inner platform 22 can be driven to move by controlling the two sets of parallel ropes 33 which are oppositely arranged on the inner platform 22 in a front-back manner, and then the inner platform 22 drives the transmission mechanism 23 to move, so that the actuator 24 correspondingly rotates around the central axis of the actuator in a one-dimensional manner, and the posture of an object grabbed by the actuator 24 is adjusted. That is to say, the rotation power of the actuator 24 comes from two groups of cable driving branched chains 3 which are oppositely arranged in front and back, so that an additional driving unit does not need to be installed on the movable platform 2, the movement quality is effectively reduced, and the robot equipment with low cost and high efficiency is realized. Two ends of the central branched chain 4 are respectively connected with the center of the static platform 1 and the top center of the movable platform 2 and are used for tensioning four groups of parallel ropes 33 all the time. Specifically, no matter whether the movable platform 2 is in a static state or a moving state, the central branched chain 4 always exerts a pushing force on the static platform 1 and the movable platform 2, and the pushing force and the pulling force of the parallel ropes 33 form an opposition, so that the parallel ropes 33 are always in tension, the driving redundancy of the movable platform 2 is avoided, and the whole robot forms a tensioning integral structure. The arrangement of the central branched chain 4 improves the integral rigidity of the parallel robot on one hand, so that the parallel robot has better high-speed/high-acceleration performance; on the other hand, the parallel ropes 33 are always in a tensioned state, so that the driving and restraining capabilities of the parallel ropes 33 on the movable platform 2 are ensured, and meanwhile, the parallel ropes 33 are always in a tensioned state is also an important condition that the parallel ropes 33 always form a parallelogram.

When the four-freedom-degree SCARA robot works, the roller driving assemblies 31 of the four cable driving branched chains 3 respectively and correspondingly control the retraction of the respective parallel ropes 33, so that the length of the parallel ropes between the pulley assembly 32 and the movable platform 2 can be effectively changed, the movable platform 2 has three-dimensional translational freedom, the inner platform 22 is driven by the parallel ropes 33 of the two cable driving branched chains 3 which are oppositely arranged in the front and back direction, the transmission mechanism 23 is driven by the inner platform 22, the actuator 24 has one-dimensional rotational freedom around the central axis of the actuator, and the four-freedom-degree SCARA movement is realized.

According to the lightweight high-speed four-degree-of-freedom cable-driven parallel robot 1000 provided by the embodiment of the invention, firstly, the inner platform 22 is driven through the parallel cables 33, and then the transmission mechanism 23 is driven through the inner platform 22, so that the actuator 24 has one-dimensional rotational freedom degree around the central axis of the actuator, an additional driving unit is not required to be arranged on the movable platform 2 to drive the actuator 24 to rotate, the overall mass of the movable platform 2 can be effectively reduced, and the parallel robot provided by the invention can realize low-cost and high-efficiency tasks such as high-speed grabbing and sorting. Secondly, the four groups of cable driving branched chains 3 replace a rigid rod 411 moving branched chain in the prior art to drive the movable platform 2, on one hand, the mass of the parallel robot can be greatly reduced, and the parallel robot can easily realize high speed and acceleration, so that the moving efficiency of the robot is greatly improved, the load brought by the self mass of the robot is small, and the energy consumption for driving the self movement is small; on the other hand, each group of cable driving branched chains 3 avoids complex hinges such as spherical hinges and the like which are used in large quantity by the rigid rod 411 moving branched chains in the prior art, and has low cost and simple structure. Thirdly, four groups of parallel ropes 33 are tensioned all the time by arranging the central branched chain 4, so that the driving redundancy of the movable platform 2 is avoided, the integral rigidity of the parallel robot is improved, the robot has better high-speed/high-acceleration performance, and high-dynamic motion can be realized. Fourthly, the parallel robot has the advantages of strong load capacity and high precision of the rigid parallel mechanism and also has the advantages of low inertia and large working space of the cable driving mechanism by adopting the cable driving parallel mechanism.

According to some embodiments of the present invention, in each group of cable driving branches 3, the number of the cables in the parallel cables 33 is two, the number of the pulley assemblies 32 is two, each of the two groups of pulley assemblies 32 has a cable exit point for leading out a single cable in the parallel cable 33, the movable platform 2 has two cable connection points respectively connected to the two cables, the two cable exit points and the two cable connection points are sequentially connected to form a parallelogram, and the two cable exit points and the two cable connection points in each group of cable driving branches 3 are sequentially connected to form a parallelogram. The motion of the movable platform 2 is controlled by four groups of parallel ropes 33 which always form a parallelogram, so that the movable platform 2 can realize spatial translation with three degrees of freedom, and the three rotational degrees of freedom of the movable platform 2 are limited, and the motion of the movable platform 2 is more stable and efficient. Meanwhile, the inner platform 22 is driven to move by the front and rear two sets of parallel ropes 33 which are oppositely arranged, and then the inner platform 22 drives the transmission mechanism 23 to move, so that the actuator 24 correspondingly rotates around the central axis of the actuator in one dimension, and the posture of an object grabbed by the actuator 24 is adjusted. In addition, the number of the parallel ropes 33 is two, which is advantageous for simplifying the structure of the robot.

According to some embodiments of the invention, in each group of cable-driven branches 3, the two parallel cables 33 are always deployed in parallel and synchronously under the drive of the drum drive assembly 31. Therefore, two ropes in the group of parallel ropes 33 can be always parallel to drive the movable platform 2 to realize three-degree-of-freedom spatial translation, and three rotational degrees of freedom of the movable platform 2 are limited. In a specific example, the number of the rollers 312 in the same roller driving assembly 31 is one, and one end of each of the two ropes in the same parallel rope 33 is wound on the roller 312 of the roller driving assembly 31, so that the synchronous winding and unwinding of the two ropes in one set of parallel ropes 33 can be simply and conveniently realized.

According to some embodiments of the invention, a tension sensor is provided at each rope connection point, the tension sensor being used for rope force monitoring. Therefore, on one hand, the parallel ropes 33 can be subjected to deformation compensation in the control system of the robot according to the monitoring data of the tension sensor, so that the positioning control precision of the movable platform 2 is improved; on the other hand, the condition that the cable force of the parallel cables 33 is too large or too small can be timely known according to the monitoring data of the tension sensor for processing, so as to ensure the control effect of the parallel cables 33 on the movable platform 2, for example, when the cable force is too large, the parallel cables 33 may break, when the cable force is too small, the problems of virtual dragging, loosening and the like of the parallel cables 33 occur, and the control effect of the parallel cables 33 on the movable platform 2 is affected.

According to some embodiments of the present invention, the roller driving assembly 31 includes a roller mounting seat 311, a roller 312 and a servo motor 313, the roller mounting seat 311 is fixedly mounted on the upper surface of the stationary platform 1, the roller 312 is rotatably supported on the roller mounting seat 311, one end of the parallel rope 33 is wound on the roller 312, the servo motor 313 drives the roller 312 to rotate forward and backward to change the length of the parallel rope 33 between the pulley assembly 32 and the movable platform 2, so as to control the movable platform 2 to perform three-degree-of-freedom spatial translation, and limit three rotational degrees of freedom of the movable platform 2, so that the movement of the movable platform 2 is more stable and efficient.

As shown in fig. 2, in a specific example, the drum driving assembly 31 includes a drum mounting seat 311, a drum 312, a servo motor 313, a reducer 314, and a coupling 315. Reducer 314 and servo motor 313 are coaxially fixed and installed on drum mounting seat 311, spiral grooves for winding parallel ropes 33 are carved on drum 312, the output shaft of reducer 314 and the central rotating shaft of drum 312 are fixedly connected and coaxially installed through coupler 315, and drum mounting seat 311 is fixedly installed on stationary platform 1.

According to some embodiments of the present invention, the servo motor 313 is equipped with an encoder 316. The encoder 316 is arranged to measure the rotation angle of the servo motor 313 in real time and feed back the rotation angle to the control system of the parallel robot according to the present invention to implement closed-loop control of the length of the parallel ropes 33.

According to some embodiments of the present invention, a current sensor is included in servo motor 313 and is used for rope force monitoring. Therefore, on one hand, the parallel ropes 33 can be subjected to deformation compensation in the control system of the robot according to the monitoring data of the current sensor so as to improve the positioning control precision of the movable platform 2; on the other hand, the situation that the cable force of the parallel cables 33 is too large or too small can be timely known according to the monitoring data of the current sensor for processing, so as to ensure the control effect of the parallel cables 33 on the movable platform 2, for example, when the cable force is too large, the parallel cables 33 may break, and when the cable force is too small, the problems of virtual dragging, loosening and the like of the parallel cables 33 occur, which all affect the control effect of the parallel cables 33 on the movable platform 2.

According to some embodiments of the present invention, as shown in fig. 3 and 4, the pulley assembly 32 includes an upper pulley assembly 321 and a lower pulley assembly 322; the upper pulley assembly 321 is located above the stationary platform 1 and includes an upper pulley base 3211 and an upper pulley 3212; an upper pulley block 3211 is fixed to an upper surface of the stationary platform 1, and an upper pulley 3212 is rotatably supported on the upper pulley block 3211; the upper pulley assembly 321 serves to guide and reverse the parallel ropes 33, and can make the parallel ropes 33 more smoothly move relative to the upper pulley assembly 321. The lower pulley assembly 322 is located below the static platform 1 and comprises a sleeve 3221, a rotating seat 3222, two groove pulleys 3223 and two transverse cylinders 3224; the sleeve 3221 penetrates through the static platform 1 and is fixed with the static platform 1, and the top of the rotating seat 3222 is rotatably sleeved at the lower end of the sleeve 3221; that is, the rotating seat 3222 can rotate around the central axis of the sleeve 3221 along with the movement of the parallel rope 33, so that it can be ensured that a single rope is always located in the central plane where the two grooved pulleys 3223 are located during the movement of the parallel rope 33, and on one hand, the rope can be prevented from being disengaged from the grooved pulleys 3223; on the other hand, the abrasion between the rope and the groove pulley 3223 is reduced, the service life of the rope is prolonged, and the influence on the rotation process of the rope is reduced. The axes of the two groove pulleys 3223 are positioned on the same horizontal plane, and the two groove pulleys 3223 are tangentially arranged side by side and rotatably supported on the rotating seat 3222; the two horizontal cylinders 3224 are located below the two groove pulleys 3223 and at the same height, and the axes of the two horizontal cylinders 3224 are perpendicular to the axes of the two groove pulleys 3223; two horizontal tubes 3224 are adjacently supported on the rotating seat 3222 side by side and rotatably, and a slit is formed between the two horizontal tubes 3224; the slit between the two horizontal tubes 3224 is configured to protect the rope from severe abrasion between the rope and the rotating seat 3222, and further limit the rope to a central plane where the two grooved pulleys 3223 are located, and prevent the rope from disengaging from the grooved pulleys 3223. After being led out from the roller driving assembly 31, a single rope in the parallel ropes 33 passes through the upper pulley 3212, and then sequentially passes downwards through the sleeve 3221, the groove corresponding to the tangent position of the two groove pulleys 3223 and the slit in front of the two transverse cylinders 3224 to be connected with the movable platform 2. The arrangement of the grooves corresponding to the two grooved pulleys 3223 of the lower pulley assembly 322 at the tangent point is used for guiding the rope and preventing the rope from falling off the lower pulley assembly 322.

In a specific example, as shown in fig. 4, the upper pulley assembly 321 includes an upper pulley base 3211, an upper pulley 3212, and an upper pulley shaft 3213, the upper pulley 3212 is rotatably mounted on the upper pulley base 3211 through the upper pulley shaft 3213, and both the upper pulley assembly 321 and the roller driving assembly 31 are fixed on the upper surface of the stationary platform 1. It will be appreciated that the upper pulley assembly 321 serves to guide and reverse the cable and may provide for smoother movement of the cable relative to the upper pulley assembly 321. The lower pulley assembly 322 comprises a sleeve 3221, a rotating seat 3222, two grooved pulleys 3223, two transverse cylinders 3224, a horizontal bearing 3225, two bearing shafts 3226, and two transverse cylinder shafts 3227. The rotating seat 3222 comprises an upper rotating seat and two lower rotating seats, the two lower rotating seats are symmetrically and fixedly arranged on the lower surface of the upper rotating seat and provide mounting positions for the groove pulleys 3223 and the transverse cylinder 3224, the sleeve 3221 is of a hollow structure and is used for a rope to pass through, the sleeve 3221 passes through the static platform 1 and is fixed with the static platform 1, and the upper rotating seat is rotatably arranged at the lower end of the sleeve 3221 through a horizontal bearing 3225, so that the whole rotating seat 3222 can rotate around the central axis of the sleeve 3221 relative to the static platform 1 along with the movement of the rope, and the rope is ensured to be always positioned in the central plane of the two groove pulleys 3223; the two groove pulleys 3223 are positioned between the two lower rotating seats, the axes of the two groove pulleys 3223 are positioned on the same horizontal plane, the two groove pulleys 3223 are parallelly and tangentially supported on the two lower rotating seats in a rotatable manner through two bearing shafts 3226 respectively, grooves are correspondingly formed at the tangent positions of the two groove pulleys 3223, the diameter of each groove is slightly larger than that of the rope, and the groove pulleys 3223 are used for guiding the rope and simultaneously can prevent the rope from falling off from the groove pulleys 3223; the two transverse cylinders 3224 are located below the two grooved pulleys 3223 and located at the same height, the axes of the two transverse cylinders 3224 are perpendicular to the axes of the two grooved pulleys 3223, the two transverse cylinders 3224 are respectively and rotatably sleeved on the two transverse cylinder shafts 3227, the two transverse cylinder shafts 3227 are respectively installed on the two lower rotating seats, the two transverse cylinder shafts 3227 are adjacently supported on the rotating seats 3222 side by side, a slit is formed between the two transverse cylinders 3224, the slit in front of the two transverse cylinders 3224 of the lower pulley assembly 322 is used for protecting the rope, so that the rope is prevented from being seriously worn between the rope and the rotating seats 3222, the rope can be further limited in a central plane where the two grooved pulleys 3223 are located, and the rope is prevented from being separated from the grooved pulleys 3223.

According to some embodiments of the present invention, as shown in FIG. 5, the sheave assembly 32 further includes an additional sheave assembly 323, a pressurized sheave assembly 324, and a pressure sensor 325; the extra pulley assembly 323 is located above the stationary platform 1 and includes an extra pulley seat 3231 and an extra pulley 3232, the extra pulley seat 3231 is fixed on the upper surface of the stationary platform 1, and the extra pulley 3232 is rotatably supported on the extra pulley seat 3231, for example, the extra pulley 3232 may be sleeved on an extra pulley shaft 3233, and further rotatably mounted on the extra pulley seat 3231 through the extra pulley shaft 3233; the pressed pulley assembly 324 is located below the stationary platform 1 and includes a pressed pulley seat 3241 and a pressed pulley 3242, the pressed pulley 3242 is rotatably supported on the pressed pulley seat 3241, for example, the pressed pulley 3242 may be sleeved on a pressed pulley shaft 3243, and further rotatably mounted on the pressed pulley seat 3241 through the pressed pulley shaft 3243; the pressure sensor 325 is fixed between the pressed pulley seat 3241 and the lower surface of the stationary platform 1, and the pressure sensor 325 is used for monitoring the pressure applied to the pressed pulley assembly 324; individual ones of the parallel cords 33 exit the roller drive assembly 31, pass over additional pulley 3232, then down through the stationary platform 1 over compression pulley 3242, then up through the stationary platform 1 over upper pulley 3212. It will be appreciated that additional pulley 3232 and compressed pulley 3242 may each function to guide and divert a rope, as shown in fig. 5, which is guided and diverted by additional pulley 3232 and compressed pulley 3242 in turn, passes downwardly through stationary platform 1 and then upwardly through stationary platform 1. The pressure sensor 325 is provided to monitor the pressure applied to the pressure sheave 3242 by the rope, wherein when the ropes on both sides of the pressure sheave 3242 are vertically arranged up and down, the pressure monitored by the pressure sensor 325 is twice the rope force on the rope, so that the pressure sensor 325 can transmit the monitored pressure back to the control system of the parallel robot of the present invention to calculate the rope force on the rope. Thus, on the one hand, the deformation compensation can be carried out on the parallel ropes 33 in the control system of the robot according to the monitoring data of the pressure sensor 325, so that the positioning control precision of the movable platform 2 is improved; on the other hand, the situation that the cable force of the parallel cables 33 is too large or too small can be timely known according to the monitoring data of the pressure sensor 325 for processing, so as to ensure the control effect of the parallel cables 33 on the movable platform 2, for example, when the cable force is too large, the parallel cables 33 may break, and when the cable force is too small, the problems of virtual dragging, loosening and the like of the parallel cables 33 may occur, and the control effect of the parallel cables 33 on the movable platform 2 may be affected.

According to some embodiments of the invention, central branch 4 comprises a tensioning unit 41, an upper end hinge 42 and a lower end hinge 43; the upper end of the tension unit 41 is connected to the center of the stationary platform 1 by an upper end hinge 42, and the lower end of the tension unit 41 is connected to the center of the outer upper platform 211 by a lower end hinge 43. The upper end hinge 42 and the lower end hinge 43 are arranged to enable two ends of the tensioning unit 41 to have corresponding freedom of movement, so that the tensioning unit 41 can correspondingly swing along with the movement of the movable platform 2. The two ends of the tensioning unit 41 are respectively connected with the center of the static platform 1 and the center of the outer upper platform 211 through the upper end hinge 42 and the lower end hinge 43, no matter the outer platform 21 is in a static state or a moving state, the tensioning unit 41 can always apply thrust to the outer platform 21, the thrust and the tension of the parallel ropes 33 form countermeasures, so that the parallel ropes 33 are always tensioned, the whole robot forms a tensioning integral structure, the integral rigidity of the parallel robot is improved, meanwhile, the parallel ropes 33 are always tensioned, which is an important condition for ensuring the driving and restraining capability of the parallel ropes 33 and the parallelogram formation of the parallel ropes 33, and the high-speed/high-acceleration performance of the robot can be effectively improved, namely, the movable platform 2 can realize high-speed stable movement.

According to some embodiments of the invention, the tensioning unit 41 is a passive tensioning unit or an active tensioning unit. The passive tensioning unit is a passive way of tensioning the rope, for example by applying an auxiliary tensioning force to the moving platform 2 by means of a spring or by applying an auxiliary tensioning force to the moving platform 2 by means of a cylinder 413; the active tensioning unit is used for tensioning the rope in an active manner, for example, by using a hydraulic cylinder 415 or an electric push rod 414, and applying a suitable auxiliary tensioning force to the movable platform 2 by actively adjusting the pushing force or the length output by the hydraulic cylinder 415 or the electric push rod 414. The tensioning unit 41 is adopted to tension the parallel ropes 33, so that the driving redundancy of the movable platform 2 is avoided, the control is easy, the movement space of the movable platform 2 is larger, and the cost is low.

According to some embodiments of the invention, as shown in fig. 6 and 7, the passive tensioning unit comprises a rigid rod 411 and a first spring 412; the upper end hinge 42 is composed of a first universal hinge 421 and a first moving pair 422, and comprises an inner ring 4211, a middle ring 4212 and an outer ring 4213 from inside to outside respectively, a first revolute pair 4214 is arranged between the inner ring 4211 and the middle ring 4212, a second revolute pair 4215 is arranged between the middle ring 4212 and the outer ring 4213, the rotation axis of the first revolute pair 4214 is vertical to the rotation axis of the second revolute pair 4215, so that the first universal hinge 421 is formed, the outer ring 4213 is fixed in a central hole 221 of the static platform 1, and a second shaft bearing 4221 is arranged on the inner ring 4211; it will be appreciated that the inner ring 4211 may rotate about the central axis of the first revolute pair 4214 and the middle ring 4212 may rotate about the central axis of the second revolute pair 4215, such that the first universal hinge 421 has two rotational degrees of freedom. The upper end of the rigid rod 411 passes through the second shaft bearing 4221, thus constituting a first sliding pair 422; it will be appreciated that the rigid bar 411 may move up and down along the second axis bearing 4221 to increase or decrease the length of the rigid bar 411 between the moving platform 2 and the stationary platform 1 following the movement of the moving platform 2. The lower end hinge 43 is a second universal hinge or a first spherical hinge, and the lower end of the rigid rod 411 is connected with the lower end hinge 43; it will be appreciated that the lower end hinge 43 has two degrees of rotational freedom so that the passive tension unit can swing in conformity with the movement of the moving platform 2. The first spring 412 is always in a compressed state and sleeved on the rigid rod 411, and two ends of the first spring 412 are respectively connected with the upper end hinge 42 and the lower end hinge 43, so that due to the characteristics of the spring, the spring in the compressed state can generate elastic force opposite to the compression direction to act on the upper end hinge 42 and the lower end hinge 43 and further act on the static platform 1 and the movable platform 2, and therefore the spring opposes to the tensile force of the rope, and the rope is tensioned. It should be noted that, the passive tensioning unit of this embodiment can select springs with different stiffness and length parameters according to the load, acceleration and stiffness requirements of the parallel robot of the present invention, so as to provide a suitable tensioning force for the rope when in use, and reduce the load and energy consumption caused by the introduction of the spring force while effectively tensioning the parallel rope 33.

According to some embodiments of the present invention, as shown in fig. 8, the passive tension unit is a cylinder 413, the upper hinge 42 is a third universal hinge 423 or a second ball hinge, the lower hinge 43 is a fourth universal hinge or a third ball hinge, the upper end of the cylinder 413 is connected to the upper hinge 42, and the lower end of the cylinder 413 is connected to the lower hinge 43. Here, the third universal hinge 423 or the second spherical hinge is used to enable the upper end of the air cylinder 413 to have two rotational degrees of freedom, so that the upper end of the air cylinder 413 can swing around the center of the upper hinge 42 along with the movement of the movable platform 2, and the fourth universal hinge or the third spherical hinge is used to enable the lower end of the air cylinder 413 to have two rotational degrees of freedom, i.e., the lower end of the air cylinder 413 can swing along with the movement of the movable platform 2. It should be noted that, the passive tensioning unit in this embodiment may replace the air cylinder 413 of different models according to the requirements of the load, acceleration and rigidity of the parallel robot of the present invention, and the air cylinder 413 may dynamically adjust the air supply pressure, so as to provide an appropriate tensioning force for the parallel rope 33, and reduce the load and energy consumption caused by the introduction of the thrust of the air cylinder 413 while effectively tensioning the parallel rope 33.

In a specific example, as shown in fig. 11, the third universal hinge 423 includes a third inner ring 4231, a third middle ring 4232 and a third outer ring 4233 from inside to outside, a third revolute pair 4234 is disposed between the third inner ring 4231 and the third middle ring 4232, a fourth revolute pair 4235 is disposed between the third middle ring 4232 and the third outer ring 4233, and a rotation axis of the third revolute pair 4234 is perpendicular to a rotation axis of the fourth revolute pair 4235, so as to form the third universal hinge 423.

According to some embodiments of the present invention, as shown in fig. 9, the active tensioning unit is an electric push rod 414, the upper end hinge 42 is a fifth universal hinge or a fourth spherical hinge, the lower end hinge 43 is a sixth universal hinge or a fifth spherical hinge, the upper end of the electric push rod 414 is connected to the upper end hinge 42, and the lower end of the electric push rod 414 is connected to the lower end hinge 43. Specifically, the electric push rod 414 actively adjusts the length or the thrust output by the electric push rod 414 by adopting a position closed-loop control, a force closed-loop control or a force position hybrid control mode, so as to provide a suitable tension force for the parallel ropes 33, reduce the load and the energy consumption introduced by the thrust of the electric push rod 414 while effectively ensuring the rope tension, and when the load on the movable platform 2 is too large, the electric push rod 414 can also provide a tension force, thereby improving the load capacity of the parallel robot of the present invention. The active tensioning unit of this embodiment can replace the electric push rod 414 with different models according to the load, acceleration and rigidity requirements of the parallel robot of the present invention, so as to adapt to different use requirements.

Further, the shape and the structure of the fifth universal hinge are the same as those of the third universal hinge 423, and each of the fifth universal hinge also includes a third inner ring 4231, a third middle ring 4232 and a third outer ring 4233 from inside to outside, a third revolute pair 4234 is arranged between the third inner ring 4231 and the third middle ring 4232, a fourth revolute pair 4235 is arranged between the third middle ring 4232 and the third outer ring 4233, and the rotation axis of the third revolute pair 4234 is perpendicular to the rotation axis of the fourth revolute pair 4235.

According to some embodiments of the present invention, as shown in fig. 10, the active tensioning unit is a hydraulic cylinder 415, the upper end hinge 42 is a seventh universal hinge or a sixth spherical hinge, the lower end hinge 43 is an eighth universal hinge or a seventh spherical hinge, the upper end of the hydraulic cylinder 415 is connected to the upper end hinge 42, and the lower end of the hydraulic cylinder 415 is connected to the lower end hinge 43. Specifically, the hydraulic cylinder 415 actively adjusts the length or the thrust output by the hydraulic cylinder 415 by adopting a position closed-loop control mode, a force closed-loop control mode or a force position mixed control mode, so that a suitable tension force is provided for the parallel ropes 33, the load and the energy consumption caused by the thrust of the hydraulic cylinder 415 are reduced while the rope tension is effectively ensured, and when the load on the movable platform 2 is overlarge, the hydraulic cylinder 415 can also provide a tension force, so that the load capacity of the parallel robot is improved. The active tensioning unit of this embodiment can replace the hydraulic cylinders 415 of different models according to the load, acceleration and rigidity requirements of the parallel robot of the present invention, so as to adapt to different use requirements.

Further, the seventh universal hinge has the same shape and structure as the third universal hinge 423, and also includes a third inner ring 4231, a third middle ring 4232 and a third outer ring 4233 from inside to outside, respectively, a third revolute pair 4234 is arranged between the third inner ring 4231 and the third middle ring 4232, a fourth revolute pair 4235 is arranged between the third middle ring 4232 and the third outer ring 4233, and a rotation axis of the third revolute pair 4234 is perpendicular to a rotation axis of the fourth revolute pair 4235.

According to some embodiments of the present invention, as shown in fig. 12 and 13, the transmission mechanism 23 includes a lead screw 231 and a lead screw nut 232, an upper end and a lower end of the lead screw 231 are rotatably supported at a center of the outer upper platform 211 and a center of the outer lower platform 212, respectively, for example, the upper end and the lower end of the lead screw 231 may be rotatably supported at the center of the outer upper platform 211 and the center of the outer lower platform 212, respectively, by bearings, the lead screw nut 232 is disposed on the lead screw 231, the lead screw 231 is threadedly coupled with the lead screw nut 232, the inner platform 22 has a center hole 221, the inner platform 22 is fixedly sleeved on an outer periphery of the lead screw nut 232 by the center hole 221, and the actuator 24 is coaxially fixed at the lower end of the lead screw 231. When the actuator 24 needs to rotate around the central axis of the actuator, the two groups of parallel ropes 33 connected to the inner platform 22 are synchronously retracted according to a specific speed, as the length of the parallel cables 33 between the mobile platform 2 and the sheave assemblies 32 decreases, the inner platform 22 moves upward relative to the outer platform 21, thereby rotating the lead screw 231 in one direction, and the lead screw 231 can drive the actuator 24 to rotate in one direction, when the length of the parallel rope 33 between the movable platform 2 and the pulley assembly 32 is increased, the inner platform 22 can move downwards relative to the outer platform 21 by the self-gravity of the inner platform 22 or the thrust generated by other components arranged on the inner platform 22, so that the inner platform 22 can drive the screw rod 231 to rotate in the other direction, and the screw rod 231 can drive the actuator 24 to rotate in the opposite direction, so that the actuator 24 can rotate around the central axis in one dimension.

As shown in fig. 12 and 13, in some embodiments of the present invention, the transmission mechanism 23 further includes a polish rod 233 and a second spring 234, the polish rod 233 passes through the through hole of the inner platform 22, the upper end and the lower end of the polish rod 233 are respectively fixed on the outer upper platform 211 and the outer lower platform 212, respectively, and the second spring 234 is sleeved on the polish rod 233 in a compressed state and is located between the outer upper platform 211 and the inner platform 22. Here, the polish rod 233 is provided to guide the movement of the inner platform 22 so that the inner platform 22 can move in the axial direction of the polish rod 233, and the movement is more smooth. The second spring 234 is sleeved outside the polished rod 233, on one hand, when the inner platform 22 moves downwards, the second spring 234 can provide a pushing force for the inner platform 22 to move downwards, and compared with a mode of driving the inner platform 22 to move downwards by using the self gravity of the inner platform 22, a mode of pushing the inner platform 22 to move downwards by using the second spring 234 is more efficient and controllable; on the other hand, it is ensured that the ropes connected to the inner platform 22 and the outer platform 21 are tensioned, and uncontrolled movements of the inner platform 22 in the direction of the polished rod 233 are avoided. It should be noted that, when the passive tension unit includes the rigid rod 411 and the first spring 412, the total stiffness of the second spring 234 is less than the total stiffness of the first spring 412, because if the total stiffness of the second spring 234 is greater than the total stiffness of the first spring 412, when the parallel rope 33 drives the moving platform 2 to move upwards, the first spring 412 is firstly pressed to deform, so as to change the overall position of the moving platform 2, and therefore, the normal use of the parallel robot of the present invention can be satisfied only when the total stiffness of the second spring 234 is less than the total stiffness of the first spring 412.

Specifically, a plurality of the polish rods 233 are symmetrically arranged at intervals, for example, two, four, etc., as shown in fig. 12, when four polish rods 233 are arranged, the movement stability of the inner platform 22 is good.

According to some embodiments of the present invention, as shown in fig. 12 and 13, the transmission mechanism 23 further comprises a second linear bearing 235, the second linear bearing 235 being mounted in the through hole, the polished rod 233 passing through the second linear bearing 235. The second linear bearing 235 is disposed to make the inner platform 22 move smoothly relative to the polish rod 233, and reduce friction between the polish rod 233 and the inner platform 22.

According to some embodiments of the present invention, as shown in fig. 14 and 15, the transmission mechanism 23 includes a lateral support shaft 236, a lateral bevel gear 237, a rotation shaft 238, and a horizontal bevel gear 239; a lateral support shaft 236 extends in the left-right direction between the outer upper platform 211 and the outer lower platform 212, and the left end and the right end of the lateral support shaft 236 are fixed to the outer platform 21, respectively; inner platform 22 is rotatably supported on transverse support shaft 236; a transverse bevel gear 237 is provided on the inner platform 22; the rotating shaft 238 is vertically arranged, and the rotating shaft 238 is rotatably supported on the center of the outer lower platform 212 and the transverse supporting shaft 236; a horizontal bevel gear 239 is provided on the rotating shaft 238, the horizontal bevel gear 239 meshing with the lateral bevel gear 237; the actuator 24 is coaxially fixed to the lower end of the rotary shaft 238. When the actuator 24 needs to rotate around the central axis of the actuator 24, one parallel rope 33 of the two sets of parallel ropes 33 connected to the inner platform 22 is controlled to retract, the other parallel rope 33 of the two sets of parallel ropes 33 is controlled to unwind, so as to drive the inner platform 22 to rotate around the transverse support shaft 236 relative to the outer platform 21, and accordingly, the transverse bevel gear 237 mounted on the inner platform 22 rotates along with the transverse rope, the horizontal bevel gear 239 engaged with the actuator is driven to rotate around the axis of the rotating shaft 238, the rotation of the horizontal bevel gear 239 drives the rotating shaft 238 to rotate, so that the actuator 24 connected at the lower end rotates around the vertical axis, and the one-dimensional rotation freedom degree of the actuator 24 around the central axis of the actuator is realized.

Further, as shown in fig. 14 and 15, there are two horizontal bevel gears 239, one of the horizontal bevel gears 239 being located above the lateral support shaft 236, and the other horizontal bevel gear 239 being located below the lateral support shaft 236; the lateral bevel gears 237 are two and are each a half-section bevel gear, one of which is located on the left side of the rotating shaft 238 and meshes with one of the two horizontal bevel gears 239, and the other of which is located on the right side of the rotating shaft 238 and meshes with the other of the two horizontal bevel gears 239. It can be understood that by arranging two groups of horizontal bevel gears 239 and transverse bevel gears 237 which are meshed with each other to carry out dispersed stress, the overall stress is symmetrical, and the force transmission is stable.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like are intended to mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A lightweight high-speed four-degree-of-freedom cable-driven parallel robot is characterized by comprising:

a static platform;

2. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 1, wherein in each group of the cable-driven branched chains, the number of the cables in the parallel cables is two, the number of the pulley assemblies is two, each of the two groups of the pulley assemblies has a cable exit point for leading out a single cable in the parallel cables, the movable platform has two cable connection points correspondingly connected to the two cables, and the two cable exit points and the two cable connection points are sequentially connected to form a parallelogram.

3. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 3, wherein in each group of cable-driven branched chains, the two cables are always wound and unwound in parallel and synchronously under the driving of the drum driving assembly.

4. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 2, wherein a tension sensor is provided at each cable connection point, and the tension sensor is used for monitoring cable force of a cable.

5. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 1, wherein the drum driving assembly includes a drum mounting seat fixedly mounted on an upper surface of the stationary platform, a drum rotatably supported on the drum mounting seat, one end of the parallel cable is wound around the drum, and a servo motor drives the drum to rotate forward and backward to change a length of the parallel cable between the pulley assembly and the movable platform.

6. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 5, wherein the servo motor is equipped with an encoder.

7. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 5, wherein a current sensor is provided in the servo motor, and the current sensor is used for monitoring a cable force of a cable.

8. The lightweight high-speed four degree-of-freedom cable-driven parallel robot of claim 1, wherein the sheave assembly comprises an upper sheave assembly and a lower sheave assembly;

the upper pulley assembly is positioned above the static platform and comprises an upper pulley seat and an upper pulley; the upper pulley seat is fixed on the upper surface of the static platform, and the upper pulley is rotatably supported on the upper pulley seat;

the lower pulley assembly is positioned below the static platform and comprises a sleeve, a rotating seat, two groove pulleys and two transverse cylinders; the sleeve penetrates through the static platform and is fixed with the static platform, and the top of the rotating seat is rotatably sleeved at the lower end of the sleeve; the axes of the two groove pulleys are positioned on the same horizontal plane, and the two groove pulleys are tangentially supported on the rotating seat side by side and can rotate; the two transverse cylinders are positioned below the two groove pulleys and at the same height, and the axes of the two transverse cylinders are perpendicular to the axes of the two groove pulleys; the two transverse cylinders are adjacently arranged side by side and rotatably supported on the rotating seat, and a slit is formed between the two transverse cylinders; and after being led out from the roller driving assembly, a single rope in the parallel ropes passes through the upper pulley, sequentially passes through the sleeve, the grooves corresponding to the two groove pulleys at the tangent positions and the slits in front of the two transverse cylinders downwards and is connected with the movable platform.

9. The lightweight high-speed four degree-of-freedom cable-driven parallel robot of claim 8, wherein the sheave assembly further comprises an additional sheave assembly, a pressurized sheave assembly, and a pressure sensor; the additional pulley assembly is positioned above the static platform and comprises an additional pulley seat and an additional pulley, the additional pulley seat is fixed on the upper surface of the static platform, and the additional pulley is rotatably supported on the additional pulley seat; the pressure pulley assembly is positioned below the static platform and comprises a pressure pulley seat and a pressure pulley, the pressure pulley is rotatably supported on the pressure pulley seat, and the pressure sensor is fixed between the pressure pulley seat and the lower surface of the static platform; and a single rope in the parallel ropes is led out from the roller driving assembly, passes through the additional pulley, then passes through the static platform downwards, passes through the pressure-bearing pulley, then passes through the static platform upwards, and passes through the upper pulley.

10. The lightweight high-speed four degree-of-freedom cable-driven parallel robot of claim 1, wherein the central branch chain comprises a tension unit, an upper end hinge, and a lower end hinge; the upper end of the tensioning unit is connected with the center of the static platform through the upper end hinge, and the lower end of the tensioning unit is connected with the center of the outer upper platform through the lower end hinge.

11. The lightweight high-speed four degree-of-freedom cable-driven parallel robot of claim 10, wherein the tensioning unit is a passive tensioning unit or an active tensioning unit.

12. The lightweight high-speed four degree-of-freedom cable-driven parallel robot of claim 11, wherein the passive tension unit comprises a rigid rod and a first spring; the upper end hinge is composed of a first universal hinge and a first sliding pair, and is respectively an inner ring, a middle ring and an outer ring from inside to outside, a first rotating pair is arranged between the inner ring and the middle ring, a second rotating pair is arranged between the middle ring and the outer ring, the rotating axis of the first rotating pair is vertical to the rotating axis of the second rotating pair, so that the first universal hinge is formed, the outer ring is fixed in a central hole of the static platform, and a second shaft bearing is arranged on the inner ring; the upper end of the rigid rod passes through the second shaft bearing, so that a first moving pair is formed; the lower end hinge is a second universal hinge or a first spherical hinge, and the lower end of the rigid rod piece is connected with the lower end hinge; the first spring is always sleeved on the rigid rod piece in a compressed state, and two ends of the first spring are respectively connected with the upper end hinge and the lower end hinge.

13. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 11, wherein the passive tension unit is a cylinder, the upper end hinge is a third universal hinge or a second spherical hinge, the lower end hinge is a fourth universal hinge or a third spherical hinge, the upper end of the cylinder is connected to the upper end hinge, and the lower end of the cylinder is connected to the lower end hinge.

14. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 11,

the active tensioning unit is an electric push rod, the upper end hinge is a fifth universal hinge or a fourth spherical hinge, the lower end hinge is a sixth universal hinge or a fifth spherical hinge, the upper end of the electric push rod is connected with the upper end hinge, and the lower end of the electric push rod is connected with the lower end hinge.

15. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 11,

the active tensioning unit is a hydraulic cylinder, the upper end hinge is a seventh universal hinge or a sixth spherical hinge, the lower end hinge is an eighth universal hinge or a seventh spherical hinge, the upper end of the hydraulic cylinder is connected with the upper end hinge, and the lower end of the hydraulic cylinder is connected with the lower end hinge.

16. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 1, wherein the transmission mechanism includes a lead screw and a lead screw nut, an upper end and a lower end of the lead screw are rotatably supported at a center of the outer upper platform and a center of the outer lower platform, respectively, the lead screw nut is provided on the lead screw, the inner platform has a center hole, the inner platform is fixedly sleeved on an outer periphery of the lead screw nut through the center hole, and the actuator is coaxially fixed at a lower end of the lead screw.

17. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 16, wherein the transmission mechanism further comprises a polish rod passing through the through hole of the inner platform, the polish rod having upper and lower ends respectively fixed to the outer upper platform and the outer lower platform, and a second spring fitted over the polish rod in a compressed state and located between the outer upper platform and the inner platform.

18. The lightweight high-speed four degree-of-freedom cable-driven parallel robot of claim 17, wherein the transmission mechanism further comprises a second linear bearing mounted in the bore, the polished rod passing through the second linear bearing.

19. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 1,

the transmission mechanism comprises a transverse support shaft, a transverse bevel gear, a rotating shaft and a horizontal bevel gear; the transverse support shaft extends in the left-right direction between the outer upper platform and the outer lower platform, and the left end and the right end of the transverse support shaft are respectively fixed with the outer platform; the inner platform is rotatably supported on the transverse support shaft; the transverse bevel gear is arranged on the inner platform; the rotating shaft is vertically arranged and can be rotatably supported in the center of the outer lower platform and the transverse supporting shaft; the horizontal bevel gear is arranged on the rotating shaft and meshed with the transverse bevel gear; the actuator is coaxially fixed at the lower end of the rotating shaft.

20. The lightweight high-speed four-degree-of-freedom cable-driven parallel robot according to claim 19,

two horizontal bevel gears are arranged, wherein one horizontal bevel gear is positioned above the transverse supporting shaft, and the other horizontal bevel gear is positioned below the transverse supporting shaft; the horizontal bevel gears have two and be half section formula bevel gear, one of them half section formula bevel gear be located the left side of rotation axis and with two one in the horizontal bevel gear meshes, wherein another half section formula bevel gear be located the right side of rotation axis and with two another in the horizontal bevel gear meshes.