Dynamic large-load-oriented five-degree-of-freedom parallel robot and structure optimization method

Abstract

The invention discloses a five-degree-of-freedom parallel robot facing a dynamic large load and a structure optimization method. The robot comprises a rack, a movable platform, four UPS driving branch chains, a UPU driving branch chain and a working head, wherein the four UPS driving branch chains and the UPU driving branch chain are connected with the rack and the movable platform; the structures of the four UPS driving branch chains are the same, each UPS driving branch chain comprises a first moving pair, one end of each first moving pair is connected with the upper portion of the rack through a hooke joint, the other end of each first moving pair is connected with the movable platform through a spherical hinge, and the four UPS driving branch chains are distributed around the movable platform and the rack; the UPU driving branch chain comprises a second moving pair, one end of the second moving pair is connected with the moving platform through a hooke joint, and the other end of the second moving pair is connected with the working head through a hooke joint. And the working head is arranged on the movable platform and is connected with the UPU driving branched chain through a hooke joint. According to the structure optimization method, a multi-objective optimization module is integrated, and optimization objectives comprise a dynamic stiffness index, a motion / force transmission index and a working space index, so that robot structure parameters are further optimized, and the stiffness and dynamic working performance of a mechanism are improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of parallel robots, in particular to a five-degree-of-freedom parallel robot for dynamic heavy load and a structural optimization method. BACKGROUND

[0002] At present, mainstream processing equipment in the industrial field is usually based on machine tools. Such equipment has the characteristics of large load and high rigidity, but in actual application, it has the shortcomings of high equipment cost, low flexibility and manufacturing flexibility. In order to improve the flexibility of the equipment, some scholars have carried out research on processing and manufacturing by using six-degree-of-freedom serial robots, but because a very large axial contact force is needed during processing, the rigidity of the serial industrial robot itself is low, the cumulative error of the mechanism is large, and the application effect is not ideal. Because parallel robots have the characteristics of large rigidity, high motion accuracy, good dynamic response performance, easy kinematics inverse solution of the mechanism, and the like, scholars at home and abroad have been committed to the research and development of new parallel robots. The application provides a five-degree-of-freedom parallel robot for dynamic heavy load and a structural optimization method. The mechanism is cooperatively driven by five driving branch chains. Not only can the flexible motion control of multiple degrees of freedom be relied on to realize accurate attitude adjustment and trajectory following of the work head in complex curved surface processing, effectively solve the problem in complex curved surface manufacturing, but also can greatly improve the overall rigidity and carrying capacity of the mechanism to adapt to the large load demand of processing. At the same time, the structural optimization algorithm designed can further improve the rigidity and working performance of the mechanism, and provides a new scheme for solving the technical problems of insufficient rigidity of parallel robots in heavy work scenes, easy vibration under dynamic load, and positioning accuracy easily affected by load fluctuations.

[0003] The prior art is as follows: Comparison with the technology of patent CN117140487A "stirring friction additive rigid-flexible coupling redundant drive parallel robot" 1. The patent CN117140487A adopts a redundant drive parallel mechanism composed of four rigid driving branch chains (two UPR driving branch chains, one UPU driving branch chain, and one UPS driving branch chain) and one flexible driving branch chain (CDUPR bidirectional rope driving flexible branch chain); while the present application proposes a combination of five rigid driving branch chains (four UPS active driving branch chains and one UPU driving branch chain), which is different from the driving mode of patent CN117140487A. Patent CN117140487A is a rigid-flexible coupling parallel robot, and the present application is a pure rigid parallel robot, which has an essential difference.

[0004] 2、Patent CN117140487A is a four-degree-of-freedom parallel robot, including three translations and one rotation. This patent can provide five degrees of freedom, three translations and two rotations. The combination of the driving branch chains is different, and the degrees of freedom and the reachable workspace are completely different.

[0005] Comparison with the technology of patent CN112621723A "5UPS-2RP(U) redundant drive parallel robot" 1、Patent CN112621723A contains two constraint branch chains (RP(U) passive constraint branch chain) and five drive branch chains (UPS active drive branch chain) combined to obtain a redundant drive parallel mechanism; this patent proposes a common drive mode using five rigid drive branch chains (four UPS drive branch chains and one UPU drive branch chain), all branch chains are drive branch chains, and there is no passive branch chain. The driving mode is different from that of patent CN112621723A, which is a redundant drive parallel mechanism, and there is an essential difference.

[0006] 2、The four degrees of freedom of patent CN112621723A are two translations and two rotations, while this patent can achieve five degrees of freedom, three translations and two rotations. The combination of the driving branch chains is different, and the degrees of freedom and the reachable workspace are not completely the same.

[0007] 3、Patent CN112621723A uses a redundant drive mode, which needs to solve the force distribution conflict problem among multiple drives, and the control difficulty is large. This patent matches the number of drive branch chains with the number of degrees of freedom, and does not need to handle the redundant force distribution problem, so the control logic is simpler.

[0008] Comparison with the technology of patent CN209019755U "Five-degree-of-freedom 4-UPS / UPU automatic implantation device for cochlear pre-bending electrode" 1、The 4UPS / UPU of patent CN209019755U is a parallel device for automatic implantation of cochlear pre-bending electrode, and the design threshold of the overall stiffness of the mechanism is low. This patent has higher requirements for the stiffness and other dynamic performance of the mechanism for dynamic large load demand, which determines that the structure strength design of the mechanism branch chain, joint connection stiffness optimization, etc. of this patent need to use different technical solutions from patent CN209019755U. This patent provides a structure optimization algorithm for dynamic large load to better meet the stable operation demand under large load working condition, and the application purpose and application method are different from patent CN209019755U.

[0009] 2. The ball joints of the 4UPS / UPU in patent CN209019755U are symmetrically placed, while this patent optimizes the ball joint layout by using a structural algorithm under dynamic large loads. By adjusting the circumferential distribution angle between the ball joints and the center of the mechanism in the four UPS drive chains, singular configurations during movement can be effectively avoided. This ensures that the mechanism maintains stable five-degree-of-freedom motion capability within the large range of motion required for complex curved surface processing, meeting the stringent requirements of processing operations for the reliability of the mechanism's motion.

[0010] Technical Comparison with Patent CN101493307A / CN101493307B "Parallel Five-Coordinate Measuring Machine Mechanism" 1. The 4UPS / UPU of patents CN101493307A / CN101493307B is a five-axis measuring machine mechanism with a relatively low design threshold for the overall stiffness of the mechanism. However, this patent is designed for dynamic high load requirements and places higher demands on the dynamic performance of the mechanism, such as stiffness. This determines that this patent must adopt different technical solutions from patents CN101493307A / CN101493307B in terms of the strength design of the mechanism's branch structure and the optimization of the stiffness of the joint connection. Furthermore, this patent provides a structural optimization algorithm for dynamic high loads to better meet the stable operation requirements under high load conditions, which is different from the application purpose and application method of patents CN101493307A / CN101493307B.

[0011] 2. Patents CN101493307A / CN101493307B's 4UPS / UPU do not specify clear technical requirements or limitations for key structural parameters such as the layout design and dimensions of its ball joints, Hooke joints, and sliding pairs. In contrast, this patent, targeting dynamic high-load application scenarios, uses a structural optimization algorithm to obtain a set of structural parameters for ball joints, Hooke joints, sliding pairs, etc. This not only enables the mechanism to effectively avoid singular configurations during motion and ensures that the mechanism maintains stable five-degree-of-freedom motion capability within the large range of motion required for complex curved surface processing, but also improves the rigidity and reliability of the mechanism, meeting the stringent requirements of processing operations for the reliability of the mechanism's motion. Summary of the Invention

[0012] The purpose of this invention is to improve the problems of low flexibility and insufficient stiffness of existing machine tools and serial robots, and to provide a five-degree-of-freedom parallel robot and structural optimization method for dynamic heavy loads. The mechanism realizes two rotational and three translational degrees of freedom, enabling precise posture adjustment and trajectory following of the working head in the machining of complex curved surfaces, effectively solving the problem of heavy loads in machining. At the same time, the designed structural optimization algorithm can further improve the stiffness and working performance of the mechanism, so as to solve the technical problems of insufficient stiffness of parallel robots in heavy operation scenarios, easy vibration under dynamic loads, and positioning accuracy being easily affected by load fluctuations.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A five-degree-of-freedom parallel robot designed for dynamic large loads is characterized by comprising a frame, a moving platform, a first drive chain and a second drive chain connecting the frame and the moving platform, and a work head fixed at the center of the moving platform for processing operations. The drive chain includes a sliding joint that serves as a drive joint. One end of the sliding joint is connected to the upper part of the frame via a Hooke joint, and the other end is connected to a ball joint mounted on the moving platform. The ball joints are distributed on a circle centered on the center of the moving platform and are asymmetrically distributed. The second drive chain includes a second sliding joint serving as a drive joint. One end of the second sliding joint is connected to the upper part of the frame via a second Hooke hinge, and the other end is connected to the working head via a third Hooke hinge. The third Hooke hinge includes an upper Hooke hinge assembly connected to the second sliding joint, a lower Hooke hinge assembly connected to the working head, and a cross hinge shaft. Both the upper and lower Hooke hinge assemblies are provided with hinge holes, and the cross hinge shafts are respectively inserted into the hinge holes, so that the moving platform has two rotational degrees of freedom to rotate along the two rotation axes of the cross hinge shaft and three translational degrees of freedom to translate along the three coordinate axes of the spatial rectangular coordinate system.

[0014] As a preferred technical solution of the present invention: four drive branches are provided, and the four drive branches are identical in structure; one drive branch is provided, and the drive branch is located at the center of the frame; the drive branches are distributed on circles centered on the drive branch.

[0015] As a preferred technical solution of the present invention: the movable pair includes a first fixed end and a first telescopic end installed on the first fixed end and moving relative to the first fixed end. The first fixed end is connected to the upper part of the frame through a Hooke hinge, and the first telescopic end is connected to the moving platform through a ball joint. The second movable joint includes a second fixed end and a second telescopic end mounted on the second fixed end and moving relative to the second fixed end. The second fixed end is connected to the upper part of the frame through a second Hooke hinge, and the second telescopic end is fixedly connected to the working head through a third Hooke hinge.

[0016] As a preferred technical solution of the present invention: the upper part of the frame is symmetrically provided with a first mounting hole for installing the first fixed end along its axial direction, and a second mounting hole for installing the second fixed end is provided at the center position of the upper part.

[0017] As a preferred embodiment of the present invention: a hinge support is provided on each of the first and second Hooke hinges, and a hinge hole and a hinge shaft are provided on the hinge support. The hinge hole and the hinge shaft intersect at a point. The hinge shaft of the hinge support on the first Hooke hinge is rotatably installed in a first mounting hole, and the hinge hole is connected to a rotating shaft on a first fixed end. The hinge shaft of the hinge support on the second Hooke hinge is rotatably installed in a second mounting hole, and the hinge hole is connected to a rotating shaft on a second fixed end.

[0018] As a preferred embodiment of the present invention, motors are respectively installed at the ends of the first and second movable pairs for driving their movement.

[0019] As a preferred technical solution of the present invention, the frame is integrally cast.

[0020] A structural optimization method for a five-DOF parallel robot under dynamic large loads, characterized by the following steps: Step S1: Initialize the component dimensions, joint stiffness matching, and drive unit layout of the key mechanisms; Step S2: Construct a dynamic large load structural optimization function, which is based on workspace index, motion / force transmission index, and dynamic stiffness index; Step S3: Solve for the objective function value of the mechanism under heavy load conditions; Step S4: Determine whether the objective function value meets the preset structural performance threshold. If it does not meet the threshold, use an optimization algorithm to iteratively optimize the component size, joint stiffness matching and drive layout, update the design parameters and return to step S3 to recalculate. If it meets the threshold, proceed to the next step. Step S5: When the function value meets the threshold requirement, terminate the iteration and obtain the optimized set of selected structure parameters.

[0021] As a preferred technical solution of the present invention: in step S4, the optimization algorithm is one or more of particle swarm optimization, genetic algorithm, and simulated annealing algorithm.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention presents a five-DOF parallel robot designed for dynamic, high-load applications. Compared to traditional parallel machine tools and redundantly driven parallel robots, this patented parallel robot offers superior rigidity and load-bearing capacity, enabling it to stably withstand the large axial contact forces and dynamic loads required during machining. This avoids machining accuracy deviations due to insufficient rigidity and meets the stable operation requirements under heavy load conditions. Furthermore, compared to the shortcomings of traditional parallel machine tools (poor flexibility and difficulty in adapting to complex curved surface machining) and redundantly driven parallel robots (complex structure and high control difficulty), this invention, while ensuring high rigidity and strong load-bearing performance, leverages flexible multi-DOF control to achieve precise attitude adjustment and trajectory following of the working head. The structural optimization method for the mechanism design further enhances the rigidity and dynamic performance of the mechanism, providing a new "structure + algorithm" solution to address the technical problems of insufficient rigidity, easy vibration under dynamic loads, and positioning accuracy susceptible to load fluctuations in parallel robots during heavy-duty operations.

[0023] This invention features five degrees of freedom: two rotations and three translations. These multiple degrees of freedom allow for more flexible movement of the working head, significantly expanding the product's applicability and enabling the processing and manufacturing of complex-shaped workpieces. Simultaneously, the mechanism's excellent rigidity and load-bearing capacity allow it to adapt to working scenarios such as friction stir welding and additive manufacturing. The designed structural optimization method can further improve the mechanism's rigidity and performance, providing a new solution to address the high-load technical challenges of existing parallel processing equipment. Furthermore, this invention has a simple drive structure, low control difficulty, and high reliability in practical use, making it suitable for heavy-duty handling. This invention is easy to assemble, has low processing costs, and is easily modularized for production. Attached Figure Description

[0024] Figure 1 This is a perspective view of the five-degree-of-freedom parallel robot designed for dynamic, large loads in this invention.

[0025] Figure 2 This is a side view of the five-degree-of-freedom parallel robot designed for dynamic large loads in this invention.

[0026] Figure 3 This is a flowchart of the structural optimization method for a five-degree-of-freedom parallel robot oriented to dynamic large loads in this invention.

[0027] In the diagram: 11. Hooke's hinge 1; 12. Sliding pair 1; 13. Ball joint; 51. Hooke's hinge 2; 52. Sliding pair 2; 53. Hooke's hinge 3; 511. Hinge support; 531. Upper Hooke's hinge assembly; 532. Cross hinge shaft; 533. Lower Hooke's hinge assembly; 6. Frame; 7. Moving platform; 8. Working head; 9. Motor; S1. Drive chain 1; S2. Drive chain 2. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: like Figures 1-2 As shown, the five-degree-of-freedom parallel robot for dynamic large loads proposed in this invention includes a frame 6 and a moving platform 7, as well as four drive branches S1 and one drive branch S2 connecting the frame 6 and the moving platform 7. Each of the drive branches S1 has the same structure, including a sliding joint 12. The sliding joint 12 serves as a drive joint and includes a first fixed end and a first telescopic end mounted on the first fixed end and moving relative to the first fixed end. The first fixed end is connected to the frame 6 via a Hooke joint 11, and the first telescopic end is connected to the moving platform 7 via a ball joint 13.

[0029] The Hooke hinge 51 of the second drive chain S2 is located at the center of the frame 6. The Hooke hinges 11 of the four first drive chains are evenly distributed on the frame 6. The ball joints 13 are asymmetrically distributed on the moving platform 7. The four first drive chains S1 are distributed around the second drive chain S2. The second drive chain S2 includes a second sliding joint 52, which serves as a drive joint. It includes a second fixed end and a second telescopic end that is mounted on the second fixed end and moves relative to the second fixed end. The second fixed end is connected to the frame 6 through the second Hooke hinge 51, and the second telescopic end is fixedly connected to the working head 8 through the third Hooke hinge 53.

[0030] The Hooke hinge 3 53 is composed of an upper Hooke hinge assembly 531, a cross hinge shaft 532 and a lower Hooke hinge assembly 533.

[0031] Specifically, the "Hooke's hinge" structure used in this embodiment is a commonly used connection structure in the art. Hooke's hinge 11 and Hooke's hinge 251 can use the same connection structure, such as... Figure 1 and Figure 2 As shown, a hinge support 511 is provided on Hooke hinge 11 and Hooke hinge 2 51 respectively. The hinge support 511 is provided with a hinge hole and a hinge shaft. The hinge hole and the hinge shaft intersect at one point. The hinge shaft of the hinge support 511 on Hooke hinge 11 is rotatably installed in the first mounting hole. The hinge hole is connected to the rotating shaft on the first fixed end. The hinge shaft of the hinge support 511 on Hooke hinge 2 51 is rotatably installed in the second mounting hole. The hinge hole is connected to the rotating shaft on the second fixed end.

[0032] Similarly, such as Figure 2As shown, the Hooke hinge 3 53 includes an upper Hooke hinge assembly 531 connected to the moving end of the sliding pair 2 52 and a lower Hooke hinge assembly 533 connected to the working head 8. It also includes a cross hinge shaft 532. Each Hooke hinge assembly is provided with a hinge hole. The cross hinge shaft 532 passes through the hinge holes in the two Hooke hinge assemblies respectively, so that the moving platform 7 has two rotational degrees of freedom to rotate around the two rotation axes of the cross hinge shaft 532, and three translational degrees of freedom to translate along the three coordinate axes of the spatial rectangular coordinate system.

[0033] The upper part of the frame 6 has four first mounting holes evenly distributed around the circumference, and a second mounting hole is also opened at the center of the upper part. These holes are used to accommodate the fixed ends of four sliding joints 12 and one sliding joint 52, respectively. The Hooke hinge 11 and the Hooke hinge 51 are located in the first and second mounting holes.

[0034] Specifically, the four ball joints 13 of the four driving branches S1 are distributed on a circle with the center of the moving platform 6 as the center. Their distribution shape is asymmetrical, which effectively avoids trajectory interference between branches during the movement and reduces the probability of triggering singular configurations from the structural level.

[0035] Specifically, based on actual needs and spatial arrangement requirements, the lines connecting the Hooke hinges 11 on opposite sides are 180 degrees apart, and the two hinge axes on the two Hooke hinges 11 on opposite sides are parallel.

[0036] The first movable pair 12 and the second movable pair 52 adopt linear drive devices, such as electric cylinders, hydraulic cylinders or pneumatic cylinders, or adopt telescopic rod mechanisms driven by motor 9.

[0037] Specifically, mounting holes are provided on the moving platform 7 according to the shape and structure of the working head 8 and the assembly requirements, for mounting and fixing the working head 8 to complete the processing operation.

[0038] Specifically, the specific layout, dimensions, and other structural parameters of ball joint 13, Hooke joint 11, Hooke joint 2 51, Hooke joint 3 53, sliding joint 1 51, sliding joint 2 52, etc., are calculated according to the structural optimization method, and finally the optimized parameter set is obtained according to the algorithm.

[0039] Specifically, in response to the performance requirements of the mechanism under heavy load conditions, both sliding joint 1 51 and sliding joint 2 52 of the mechanism are equipped with high-strength linear push devices, and joints such as ball joint 13, Hooke joint 11, Hooke joint 2 51, and Hooke joint 3 53 are equipped with wear-resistant reinforced components to improve load-bearing stability. In addition, the frame 6 is made of integrated casting to improve the rigidity and reliability of the mechanism.

[0040] Specifically, the support and connection functions of the frame 6 and the moving platform 7 can be designed according to the actual application requirements.

[0041] During operation, the frame 6 is fixed to the ground, and the processing work is performed using the working head 8 on the moving platform 7. Driven by the prismatic joint 12 of the four drive chains S1 and the prismatic joint 52 of the drive chains S2, the moving platform 7 rotates around the two axes of the Hooke hinge 3 53, and translates along the X, Y, and Z axes. This constitutes a parallel robot with five degrees of freedom. The directions of the two rotations and three translations are as follows: Figure 2 As indicated by the middle arrow.

[0042] This invention also proposes a structural optimization method for a five-degree-of-freedom parallel robot oriented to dynamic large loads, comprising the following steps: Step S1: Initialize the component dimensions, joint stiffness matching, and drive unit layout of the key mechanisms; Step S2: Construct a dynamic large load structural optimization function, which is based on workspace index, motion / force transmission index, and dynamic stiffness index; Step S3: Solve for the objective function value of the mechanism under heavy load conditions; Step S4: Determine whether the objective function value meets the preset structural performance threshold. If it does not meet the threshold, use an optimization algorithm to iteratively optimize the component size, joint stiffness matching and drive layout, update the design parameters and return to step S3 to recalculate. If it meets the threshold, proceed to the next step. Step S5: When the function value meets the threshold requirement, terminate the iteration and obtain the optimized set of selected structure parameters.

[0043] like Figure 3 As shown, a multi-objective structural optimization function for the mechanism under heavy load conditions is calculated. This function is based on the mechanism's workspace index, motion / force transmission index, and dynamic stiffness index. If the objective function value does not reach the preset performance threshold, the algorithm will perform multiple rounds of iterative optimization on the dimensions of key components, joint stiffness matching parameters, and drive unit layout. Finally, it outputs the optimal structural parameter scheme that meets the preset structural performance threshold, further eliminating local stiffness weaknesses, improving the dynamic response stability of the mechanism, and significantly enhancing the mechanism's deformation resistance and operational reliability under heavy load conditions. The specific implementation process is as follows: Step S1: Based on the load-bearing requirements of the mechanism and the material properties, the structural parameters such as the length of the five drive chains, the cross-sectional dimensions of the links, and the thickness of the joint connectors are initially set. Step S2: With the stiffness of the mechanism, dynamic response characteristics (natural frequency, vibration attenuation rate), workspace, and force / motion transmission performance as objectives, construct a multi-objective mathematical model by combining topology optimization and parameter optimization; Step S3: Based on the multi-objective mathematical model constructed in step S2, use numerical simulation and other methods to solve the objective function values ​​of the mechanism under the preset dynamic large load conditions; Step S4: If the objective function value in step S3 does not reach the preset structural performance threshold, the iterative optimization process is initiated. An optimization algorithm is used to iteratively optimize the component dimensions, joint stiffness matching, and drive layout. After updating the design parameters, the process returns to step 3 for recalculation. Step S5: When the calculation result of step S3 meets the preset structural performance threshold, the iteration is terminated, and the parameters are solidified and the final scheme is verified.

[0044] Specifically, the dynamic stiffness index is established by creating a complete dynamic model that includes the mechanism's inertial parameters, stiffness parameters, and damping parameters. Based on this model, the natural frequencies of the mechanism are calculated, modal characteristics are analyzed, and the dynamic response characteristics of the robot to external or internal excitations within its main operating frequency range are studied. Finally, the dynamic stiffness coefficient at a specific frequency is obtained. On this basis, isotropy (the uniformity of the vibration amplitude distribution of the moving platform in different directions in space) is used as one of the core quantitative criteria for the dynamic stiffness index. Combined with resonance margin (i.e., the ratio of the difference between the first-order natural frequency and the maximum operating frequency, used to characterize the safety of the mechanism in avoiding the resonance frequency band) and dynamic accuracy (i.e., the deviation between the actual position and the commanded position of the end effector under dynamic load, reflecting the ultimate impact of stiffness on operating accuracy), a complete dynamic stiffness evaluation system is formed to accurately characterize the mechanism's ability to resist vibration deformation caused by dynamic excitation. The motion / force transfer index describes the mapping relationship between the input motion of the driving chain and the output motion of the moving platform, and between the input driving force (or driving torque) and the output force (or output torque) of the end effector, using spiral theory. It focuses on characterizing the ability of the input driving force (or torque) to be converted into the effective output force (or torque) of the end effector along the desired direction of machining requirements, as well as the uniformity of this conversion capability within the mechanism's motion range, thus obtaining the energy transfer efficiency of the mechanism under general poses. The workspace index establishes motion constraints on the mechanism, such as interference between parallel mechanism components, the moving platform's motion not exceeding the maximum rotation range of Hooke's joints and ball joints, and avoiding singularities in the Jacobian matrix. Numerical calculations are used to solve for the set of achievable poses of the moving platform, and the number of achievable workspace points in this set is used as the quantitative result of the workspace index.

[0045] Specifically, the optimization algorithm in step S4 can use a variety of optimization algorithms such as particle swarm optimization, genetic algorithm, and simulated annealing. The specific algorithm can be selected adaptively according to the complexity of the optimization problem and the convergence efficiency requirements.

[0046] The five-DOF parallel robot of this embodiment, designed for dynamic high loads, has multiple degrees of freedom, making the movement of the working head 8 more flexible and adaptable to the processing and manufacturing of complex-shaped workpieces. Furthermore, the mechanism has good rigidity and load-bearing capacity, and can stably withstand the large axial contact force required during processing. Combined with the supporting structural optimization methods, it can better adapt to high-load working scenarios. Therefore, this invention has great advantages for industrial applications.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A five-degree-of-freedom parallel robot designed for dynamic, large loads, characterized in that: Includes a frame (6), a moving platform (7), a drive chain one (S1) and a drive chain two (S2) connecting the frame (6) and the moving platform (7), and a work head (8) fixed at the center of the moving platform (7) for processing operations. The drive chain one (S1) includes a sliding joint one (12) for use as a drive joint. One end of the sliding joint one (12) is connected to the upper part of the frame (6) through a Hooke joint one (11), and the other end is connected to a ball joint (13) installed on the moving platform (7). The ball joint (13) is distributed on a circle with the center of the moving platform (7) as the center and is asymmetrically distributed. The second drive chain (S2) includes a second sliding joint (52) for use as a drive joint. One end of the second sliding joint (52) is connected to the upper part of the frame (6) through a second Hooke hinge (51), and the other end is connected to the working head (8) through a third Hooke hinge (53). The third Hooke hinge (53) includes an upper Hooke hinge assembly (531) connected to the second sliding joint (52), a lower Hooke hinge assembly (533) connected to the working head (8), and a cross hinge shaft (532). Both the upper Hooke hinge assembly (531) and the lower Hooke hinge assembly (533) are provided with hinge holes. The cross hinge shaft (532) is inserted into the hinge holes, so that the moving platform (7) has two rotational degrees of freedom to rotate along the two rotation axes of the cross hinge shaft (532) and three translational degrees of freedom to translate along the three coordinate axes of the spatial rectangular coordinate system.

2. The five-DOF parallel robot for dynamic large loads according to claim 1, characterized in that, There are four drive branches (S1), and the four drive branches (S1) have the same structure. There is one drive branch (S2), which is located at the center of the frame. The drive branches (S1) are distributed on a circle with the drive branch (S2) as the center.

3. The five-DOF parallel robot for dynamic large loads according to claim 1, characterized in that, The movable pair (12) includes a first fixed end and a first telescopic end installed on the first fixed end and moving relative to the first fixed end. The first fixed end is connected to the upper part of the frame (6) through a Hooke hinge (11), and the first telescopic end is connected to the moving platform (7) through a ball joint (13). The second movable part (52) includes a second fixed end and a second telescopic end installed on the second fixed end and moving relative to the second fixed end. The second fixed end is connected to the upper part of the frame (6) through the second Hooke hinge (51), and the second telescopic end is fixedly connected to the working head (8) through the third Hooke hinge (53).

4. The five-DOF parallel robot for dynamic large loads according to claim 3, characterized in that, The upper part of the frame (6) is symmetrically provided with a first mounting hole for installing the first fixed end along its axial direction, and a second mounting hole for installing the second fixed end is provided at the center of its upper part.

5. The five-DOF parallel robot for dynamic large loads according to claim 1 or 4, characterized in that, Hinges (511) are provided on the first (11) and the second (51) of the Hooke hinge. The hinges (511) are provided with hinge holes and hinge shafts. The hinge holes and hinge shafts intersect at one point. The hinge shaft of the hinges (511) on the first (11) is rotatably installed in the first mounting hole. The hinge hole is connected to the rotating shaft on the first fixed end. The hinge shaft of the hinges (511) on the second (51) of the Hooke hinge is rotatably installed in the second mounting hole. The hinge hole is connected to the rotating shaft on the second fixed end.

6. The five-DOF parallel robot for dynamic large loads according to claim 1, characterized in that, Motors (9) are respectively installed at the ends of the first (12) and the second (52) moving parts for driving their movement.

7. The five-DOF parallel robot for dynamic large loads according to claim 1, characterized in that, The frame (6) is integrally cast.

8. The structural optimization method for a five-DOF parallel robot oriented towards dynamic large loads according to any one of claims 1-7, characterized in that, Includes the following steps: Step S1: Initialize the component dimensions, joint stiffness matching, and drive unit layout of the key mechanisms; Step S2: Construct a dynamic large load structural optimization function, which is based on workspace index, motion / force transmission index, and dynamic stiffness index; Step S3: Solve for the objective function value of the mechanism under heavy load conditions; Step S4: Determine whether the objective function value meets the preset structural performance threshold. If it does not meet the threshold, use an optimization algorithm to iteratively optimize the component size, joint stiffness matching and drive layout, update the design parameters and return to step S3 to recalculate. If it meets the threshold, proceed to the next step. Step S5: When the function value meets the threshold requirement, terminate the iteration and obtain the optimized set of selected structure parameters.

9. The structural optimization method for a five-degree-of-freedom parallel robot oriented towards dynamic large loads according to claim 1, characterized in that, In step S4, the optimization algorithm is one or more of particle swarm optimization, genetic algorithm, and simulated annealing algorithm.

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