A multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts

Abstract

The present invention belongs to but is not limited to the technical field of processing robots. The present invention discloses a multi-degree-of-freedom serial-parallel hybrid robot system and design method for force-controlled grinding and polishing of curved surface parts. The system includes two parts: a 1T2R parallel mechanism and a four-degree-of-freedom serial robot. The 1T2R configuration is analyzed by geometric algebra, the 3-PUU configuration of the parallel mechanism is determined, and kinematic analysis is performed to determine the serial robot configuration and DH parameters, the actuator size required for curved surface grinding and polishing blades is derived, the global force transfer coefficient is calculated to obtain the hybrid robot structure, and the hierarchical optimization design is realized based on the PSO optimization algorithm. The present invention solves the problems of insufficient rigidity and poor dexterity of the existing robot system, and meets the requirements of high precision, high rigidity and high dexterity for curved surface grinding and polishing.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the technical field of processing robots, and in particular relates to a serial-parallel hybrid robot system and method for force-controlled grinding and polishing of curved surface parts. Background Art

[0002] Curved parts are widely used in aero-engines, which also puts forward high requirements for grinding and polishing technology. In the current processing scheme, manual grinding and polishing and special machine grinding and polishing have the defects of low efficiency and fixed mode, while robot grinding and polishing has the advantages of dexterity and high flexibility, providing a better processing scheme. With the development of manufacturing equipment towards multi-function, flexibility and intelligence.

[0003] At present, robot grinding and polishing has been gradually applied to high-end processing such as large parts, complex curved surfaces, and precision manufacturing. However, the traditional serial robot configuration has inherent defects such as low cantilever beam stiffness, accumulation of structural open-loop errors, and low dexterity due to large inertia. During the surface contact processing. Due to the large vibration caused during processing. Therefore, the end effector must have high stiffness. The serial mechanism has a larger working range and motion flexibility, but it will sacrifice stiffness and accuracy, affecting the processing effect.

[0004] Compared with the serial mechanism, the parallel force control actuator has the following characteristics: 1. High rigidity. The parallel mechanism platform is supported by multiple motion branches, so the end load will be borne by each branch, and the overall mechanism has high rigidity. 2. Compact structure and low inertia. The motion branch of the parallel mechanism is shorter, the overall structure is small, and the required installation space is small. 3. Small working space. The motion branch causes the rod length to be short. The range of motion is small and the working space is small. In summary, the parallel mechanism has lower inertia and higher rigidity than the serial mechanism. Therefore, the parallel force control actuator can work at a higher speed while maintaining sufficient rigidity to provide high-precision motion. It has the advantages of light weight, high rigidity, and faster dynamic response. The parallel mechanism has the characteristics of compact structure, high rigidity, strong bearing capacity, and no cumulative error, which can achieve high flexibility and high-precision motion. Based on the above advantages, it is of great significance to carry out hybrid grinding and polishing equipment of serial positioning (macro) + terminal parallel dexterous hand (micro). Through the search of existing literature, it is found that existing hybrid robots are often only optimized for stiffness during processing. The design goals are unclear and multiple parameters are coupled. Therefore, further optimization is still needed to design normalized parameters to represent physically meaningful dexterity. On the other hand, it is found that there are no relevant patents for the design of hybrid robots under curved surface force-controlled grinding and polishing. Therefore, it is urgent to design and optimize a new multi-degree-of-freedom serial-parallel hybrid robot system for curved surface part force-controlled grinding and polishing.

[0005] Through the above analysis, the problems and defects of the prior art are as follows:

[0006] (1) The existing hybrid robot system has many kinematic indicators, but lacks a parameter mapping method that can represent the physical meaning of grinding and polishing.

[0007] (2) The kinematic and dynamic indicators affect each other, making it difficult to perform decoupling analysis. How to establish a multi-objective optimization strategy and design key indicators for grinding and polishing process parameters.

[0008] (3) Through the search of existing literature, it was found that there are currently no relevant patents for the configuration design and optimization design methods of hybrid grinding and polishing robots.

[0009] The difficulty of solving the above problems and defects is:

[0010] Hybrid robot decoupling design and optimization: Considering the surface grinding and polishing scenario, select the 2R1T structure, design a new 3-PUU architecture to build a parallel dexterous hand with better orientation ability. Establish kinematics and stiffness models for analysis, design grinding and polishing parameters and design index mapping, and realize the hybrid grinding and polishing system design under multi-parameter constraints. Design an effective grinding and polishing hybrid robot force control system.

[0011] The significance of solving the above problems and defects is:

[0012] Pay more attention to the comprehensive requirements of robot dexterity and motion performance, aiming at the structural problems of poor rigidity and dexterity of existing processing robots, as well as the mismatch and inaccuracy of parameters and grinding and polishing operations caused by not starting from actual processing requirements, and propose a hybrid robot system with parameter design optimization for grinding and polishing dexterity. It has better grinding and polishing dexterity and processing accuracy. Summary of the invention

[0013] In view of the problems existing in the prior art, the present invention provides a multi-degree-of-freedom serial-parallel hybrid robot system and method for force-controlled grinding and polishing of curved surface parts. It relates to a design principle for designing key indicators for grinding and polishing process parameters using a multi-objective optimization strategy, and in particular to a hybrid processing robot that considers the combination of serial configuration and parallel configuration in the design of a grinding force control system; it solves the problems of insufficient rigidity and poor dexterity of the existing robot system in grinding and polishing operations.

[0014] The present invention is implemented as follows: a design method for a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts comprises the following steps:

[0015] Step 1: The hybrid grinding and polishing robot includes two parts: a 1T2R parallel mechanism and a four-degree-of-freedom serial robot. The 1T2R configuration is synthesized based on geometric algebra analysis.

[0016] Step 2: Determine the number of 3 degrees of freedom of the 1T2R parallel mechanism and adopt a 3-PUU configuration, which consists of a movable platform B1B2B3, a fixed platform A1A2A3 and three identical PUU branches; each U-shaped joint consists of two vertically intersecting rotation joints; analyze the kinematics of the 3-PUU configuration based on the screw theory constraint;

[0017] Step 3: Determine the configuration of the four-degree-of-freedom serial robot. Determine that the robot contains four joints and performs four movements of x, y, z, and Rz. The first three joints are responsible for positioning, and the fourth joint performs Rz movement. Through discrete workspace analysis, the DH parameters require that its workspace diameter is 1m.

[0018] Step 4: derive the actuator size required for curved surface grinding and polishing of blades, calculate the global force transfer coefficient, and obtain the hybrid robot structure;

[0019] Step 5: Based on the actual physical constraints and workspace constraints, the global force transfer coefficient and the global dexterity index are optimized through the PSO optimization algorithm, and the hierarchical optimization design is realized with Pareto optimality as the goal.

[0020] Further, the step 1 is based on geometric algebraic analysis of 1T2R configuration synthesis and includes:

[0021] For a 2R1T non-redundant drive parallel mechanism with a certain axis, its output degrees of freedom are expressed by geometric algebra as follows:

[0022] S m =A 1 ∩A 2 ∩A 3 =G 1 ∧G 2 ∧G 3 =(e 1 )∧(c α e 2 -s α e 3 +b 2,1,m e 4 )∧(s α e 5 +c α e 6 )

[0023] Among them, A i (i=1,2,3) represents the kinematic subspace of the kinematic chain, S m represents the motion subspace of the dynamic platform of the mechanism; G i (i=1,2,3) represents the output degree of freedom of the 2R1T parallel mechanism, e represents the basis vector of the vector space, s and c represent the sin and cos functions, α represents the rotation angle around a certain axis in space, and b represents the second output degree of freedom;

[0024] Based on the above design, a basic mechanism with two rotations and one translation is determined to provide guidance for the selection of the grinding and polishing hybrid robot; among them, a new 3-PUU architecture with 2R1T degrees of freedom is selected (U represents the universal joint, and P represents the translation mechanism).

[0025] Further, the step 2 of analyzing the kinematics of the 3-PUU configuration based on the screw theory constraint includes:

[0026]

[0027] Where R and T are the rotation matrix and translation vector between the local coordinate system and the global coordinate system respectively; S is the virtual screw expressed in the local coordinate system;

[0028] The motion of the end effector is represented by:

[0029]

[0030] Among them, (a) represents the translation along the z direction, (b) represents the rotation around the x-axis of the parasitic motion along the y direction, and (c) represents the rotation around the y-axis along the x direction.

[0031] Furthermore, in the step three, the four-degree-of-freedom serial robot is analyzed through discrete workspace analysis, DH parameter design and workspace analysis are performed using Matlab Robotic Toolbox, and its workspace is analyzed through the Monte Carlo method.

[0032] Furthermore, the global force transfer coefficient is calculated in step 4 to obtain the hybrid robot structure, including: the input transfer index represents the power coefficient between the input torsion and the related transfer wrench, and the input motion / force transferability of the i-th limb is expressed as:

[0033]

[0034] The denominator and molecules are the actual power and potential maximum power of the input component respectively;

[0035] get:

[0036] λ i =|sinα i |(i=1,2,3)

[0037] For an integrated parallel manipulator, the minimum value of λi is used to evaluate the input transmittance of the entire manipulator:

[0038] λ=min(λ i )(i=1,2,3)

[0039] λ defines the input transmission index indicators and gives their physical meanings and mathematical expressions.

[0040] Furthermore, in step 5, a hierarchical optimization design is performed based on the PSO optimization algorithm. Given the task workspace and constraints, the optimal scale and structural parameters are achieved. The design parameters that need to be determined during optimization include:

[0041] (1) Scale parameters: geometric parameters of the base and end seat, working plane and global coordinate system;

[0042] (3) Structural parameters: outer diameter and wall thickness of the swing chain and intermediate rod;

[0043] According to the relationship between different performance indicators and design variables, the system model is combined with the design goals of different stages to achieve a hierarchical optimization design process.

[0044] Another object of the present invention is to provide a design method of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts. The hybrid robot system includes a 1T2R parallel mechanism and a four-degree-of-freedom serial robot.

[0045] The 1T2R parallel mechanism consists of a movable platform B1B2B3, a fixed platform A1A2A3 and three identical PUU branches; each U-shaped joint consists of two vertically intersecting rotary joints;

[0046] The four-degree-of-freedom serial robot contains four joints and can perform four movements: x, y, z, and Rz. The first three joints are responsible for positioning, and the fourth joint performs Rz movement.

[0047] Another object of the present invention is to provide a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the design method of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved parts.

[0048] Another object of the present invention is to provide a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of the design method of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved parts.

[0049] Another object of the present invention is to provide an information data processing terminal, which includes the multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts.

[0050] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0051] First, the multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved parts provided by the present invention avoids the shortcomings of poor cantilever beam stiffness, accumulated structural open-loop errors, and low dexterity due to large inertia in the structure of traditional grinding and polishing robots by hybridizing parallel and serial structures. By selecting a new 3-PUU mechanism with 2R1T degrees of freedom (U represents a universal joint, and P represents a translation mechanism), it is easier and cheaper to develop into applications and has better directional capabilities. The hierarchical optimization design based on this configuration design effectively achieves the comprehensive optimization of scale and structure. It meets the requirements of high precision, high stiffness, and high dexterity in curved surface grinding and polishing.

[0052] Second, as auxiliary evidence of the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0053] (1) The expected benefits and commercial value of the technical solution of the present invention after transformation are:

[0054] Improve the processing efficiency and quality of curved surface parts grinding and polishing, meet the high requirements of curved surface parts in fields such as aircraft engines, and thus bring higher production benefits to related enterprises. Promote the development of robot grinding and polishing technology, so that it can be more widely used in high-end processing such as large parts, complex curved surfaces, and precision manufacturing, and open up a broader market. The hybrid robot system based on the present invention has the characteristics of high rigidity, high dexterity and high precision, which can reduce production costs, improve product competitiveness, and bring considerable economic benefits to enterprises.

[0055] (2) The technical solution of the present invention fills the technical gap in the industry at home and abroad:

[0056] 1. Existing hybrid robots are often only optimized for stiffness during processing, with unclear design objectives and multi-parameter coupling. The present invention provides a design principle for key indicators of grinding and polishing process parameters using a multi-objective optimization strategy, which solves the problems of numerous kinematic indicators of existing robot systems, lack of parameter mapping methods with physical significance for grinding and polishing, and mutual influence of motion-dynamic indicators, making it difficult to perform decoupling analysis.

[0057] 2. There is no relevant patent for the design of a hybrid robot for force-controlled grinding and polishing of curved surfaces. The present invention fills this technical gap and provides a new multi-degree-of-freedom serial-parallel hybrid robot system and method for force-controlled grinding and polishing of curved surface parts.

[0058] (3) The technical solution of the present invention solves the technical problems that people have been eager to solve but have never been able to solve successfully:

[0059] 1. The traditional serial robot configuration has inherent defects such as low cantilever beam stiffness, accumulated structural open-loop errors, and low dexterity due to large inertia. During the surface contact processing, it will cause large vibrations and affect the processing effect. Although the parallel mechanism has high stiffness, it has a small working space. The present invention effectively solves this problem through the hybrid design of serial positioning (macro) + terminal parallel dexterous hand (micro), meeting the requirements of high precision, high stiffness and high dexterity in surface grinding and polishing.

[0060] 2. In the prior art, the configuration design and optimization design methods of hybrid grinding and polishing robots have not been well solved. The present invention establishes kinematic and stiffness models for analysis, designs grinding and polishing parameters and mappings with design indicators, realizes the design of a hybrid grinding and polishing system under multi-parameter constraints, and solves this technical problem.

[0061] (4) The technical solution of the present invention overcomes technical prejudice:.

[0062] In the past, the technical concept often paid more attention to the working range and movement flexibility of serial robots, while ignoring their lack of rigidity and accuracy; or paid more attention to the rigidity of parallel robots, while ignoring their limitations of small working space. The present invention overcomes this technical prejudice, gives full play to the advantages of serial and parallel robots, and realizes the high-performance application of robots in force-controlled grinding and polishing of curved surface parts through serial-parallel hybrid mode.

[0063] Third, the technical solution of the present invention solves the problems of insufficient dexterity and low force control accuracy in the prior art in industrial applications. Traditional grinding and polishing robots are usually limited in flexibility and control accuracy when facing complex curved parts, and it is difficult to meet the requirements of high-precision processing. In addition, the existing parallel or serial robot structures have their own limitations, and a single structure cannot simultaneously meet the requirements of high rigidity, high flexibility and large workspace.

[0064] By designing a multi-DOF serial-parallel hybrid robot system, the present invention combines the advantages of parallel and serial robots. The 1T2R parallel mechanism provides high rigidity and flexibility, and can perform one-dimensional translation and two-dimensional rotation, so as to better adapt to the complex shape of the curved surface. The four-DOF serial robot part ensures sufficient range of motion, can cover a large working space, and improves the accuracy of position positioning and posture adjustment through optimized design.

[0065] Through these improvements, the present invention significantly improves the processing quality and efficiency of curved surface parts grinding and polishing, achieves higher flexibility and precision control, and solves the processing bottleneck faced by traditional technologies. In addition, the optimization design based on the PSO algorithm enables the robot system to achieve global optimization in force transmission and dexterity, further improving the reliability and performance in industrial applications, thereby promoting the technological progress of advanced manufacturing technology in the field of high-precision curved surface processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 It is a flow chart of a design method of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts provided by an embodiment of the present invention.

[0067] Figure 2 It is a design appearance drawing of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts provided by an embodiment of the present invention.

[0068] Figure 3 It is a schematic diagram of the serial-parallel hybrid robot PUU configuration and its own coordinate system and virtual screws provided in an embodiment of the present invention.

[0069] Figure 4 It is a schematic diagram of the 4R+2R1T basic kinematic configuration of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts provided by an embodiment of the present invention.

[0070] Figure 5 This is a graph of workspace analysis results of the Monte Carlo method for a multi-degree-of-freedom serial-parallel hybrid robot provided in an embodiment of the present invention.

[0071] Figure 6 It is a hierarchical optimization design flow chart provided by an embodiment of the present invention.

[0072] Figure 7 The embodiment of the present invention provides a multi-degree-of-freedom serial-parallel hybrid robot system hardware composition for force-controlled grinding and polishing of curved surface parts.

[0073] Figure 8 It is a diagram of the parallel configuration optimization results of a multi-degree-of-freedom serial-parallel hybrid robot for force-controlled grinding and polishing of curved surface parts provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0074] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0075] like Figure 1As shown, a design method of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts provided by an embodiment of the present invention comprises the following steps:

[0076] S101, for the dexterous processing scenario of grinding and polishing curved surfaces, a hybrid grinding and polishing robot is designed, which is divided into two parts: a 1T2R parallel mechanism and a four-degree-of-freedom serial robot, and the 1T2R configuration synthesis is analyzed based on geometric algebra;

[0077] S102, determine the number of 3 degrees of freedom of the mechanism, adopt a 3-PUU configuration, consisting of a movable platform B 1 B 2 B 3 , a fixed platform A 1 A 2 A 3 It consists of three identical PUU branches; each U-shaped joint consists of two perpendicularly intersecting rotation joints. The kinematics of the 3-PUU configuration is analyzed based on the screw theory constraint;

[0078] S103, determining the configuration of the serial robot, determining that the robot includes 4 joints and can perform four movements (x, y, z Rz), such as the first 3 joints are responsible for position positioning, and the 4th joint can perform Rz movement. Through discrete workspace analysis, the DH parameter requires that the workspace diameter is 1m;

[0079] S104, deriving the actuator size required for curved surface grinding and polishing of blades, calculating the global force transfer coefficient, and obtaining the hybrid robot structure;

[0080] S105, based on actual physical constraints and workspace constraints, the global force transfer coefficient and the global dexterity index are optimized through the PSO optimization algorithm, with Pareto optimality as the goal, to achieve hierarchical optimization design.

[0081] The working principle of the present invention is firstly based on the processing requirements of grinding and polishing curved surface parts, and a multi-degree-of-freedom serial-parallel hybrid robot system is designed. The system is divided into two main parts: a 1T2R parallel mechanism and a four-degree-of-freedom serial robot. The 1T2R parallel mechanism realizes structural synthesis through geometric algebraic analysis, and it has the ability of one-dimensional translation and two-dimensional rotation, which is suitable for the needs of dexterous grinding and polishing.

[0082] Secondly, when designing the parallel mechanism, it was determined that it contained three degrees of freedom and adopted a 3-PUU configuration. This configuration consists of a movable platform, a fixed platform, and three identical PUU branches. Each PUU branch includes two vertically intersecting rotation joints. Through the analysis of the screw theory, the kinematic constraints of the parallel mechanism were realized.

[0083] Then, when designing the serial robot part, it was determined that it has four joints, which can perform translation in three directions (x, y, z) and rotation in one direction (Rz). Through discrete analysis of the workspace, the DH parameters were optimized to ensure that the robot's workspace diameter reaches 1 meter, thus meeting the needs of grinding and polishing large-sized curved surfaces.

[0084] Finally, the actuator size required for curved surface grinding and polishing blades is derived, the global force transfer coefficient is calculated, and the final hybrid robot structure design is obtained. In practical applications, based on physical constraints and workspace constraints, the global force transfer coefficient and dexterity index are optimized by particle swarm optimization (PSO) algorithm to achieve Pareto optimal hierarchical optimization design.

[0085] In order to solve the problems of insufficient rigidity and dexterity of existing curved surface grinding robots, the present invention provides a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts, involving a design principle of utilizing a multi-objective optimization strategy to design key indicators for grinding and polishing process parameters, and more particularly, to a hybrid processing robot that considers the combination of serial configuration and parallel configuration in the design of a grinding force control system.

[0086] Furthermore, the 1T2R configuration synthesis based on geometric algebra analysis includes:

[0087] For a 2R1T non-redundant drive parallel mechanism with a certain axis of rotation, its output degrees of freedom can be expressed by geometric algebra as follows:

[0088] S m =A 1 ∩A 2 ∩A 3 =G 1 ∧G 2 ∧G 3 =(e 1 )∧(c α e 2 -s α e 3 +b 2,1,m e 4 )∧(s α e 5 +c α e 6 )

[0089] Among them, A i (i=1,2,3) represents the kinematic subspace of the kinematic chain, S m G represents the motion subspace of the dynamic platform of the mechanism. i(i=1,2,3) represents the output degrees of freedom of the 2R1T parallel mechanism, e represents the basis vector of the vector space, s and c represent the sin and cos functions, α represents the rotation angle around a certain axis in space, and b represents the second output degree of freedom. Based on the above design, a type of basic mechanism with two rotations and one translation can be determined to provide guidance for the selection of grinding and polishing hybrid robots. Among them, a new 3-PUU architecture with 2R1T degrees of freedom is selected (U represents the universal joint and P represents the translation mechanism). The 3-PUU mechanism does not require precise spherical joints, and its rotation joints are correspondingly not restricted by the cone angle constraints of these spherical joints. Therefore, it is easier and cheaper to develop the 3-PUU mechanism into practice, and it has better orientation capabilities.

[0090] Furthermore, the kinematics of the 3-PUU configuration based on the screw theory constraint analysis includes:

[0091]

[0092] where R and T are the rotation matrix and translation vector between the local and global coordinate systems, respectively. S is the virtual screw expressed in the local coordinate system. Due to the symmetric nature of the 3-PUU structure, only one of the three limbs needs to be analyzed in its local frame. Figure 3 The PUU configuration and its own coordinate system A are shown 1 -x 1 y 1 z 1 , from which the torsional virtual screws of all five kinematic pairs can be obtained as follows:

[0093]

[0094] α i Indicates the bevel angle of the connecting rod. Based on the above, the virtual screw A of the above five screws in the local frame can be calculated. i -x i y i z i for:

[0095]

[0096] In order to transform the reciprocal screw from the local coordinate system to the global coordinate system, it is necessary to know the rotation matrix R and the translation vector T between the local coordinate system and the global coordinate system. When the mobile platform is in a horizontal configuration, it is not difficult to directly write A i -x i y i z i The three rotation angles between O-xyz and around the z-axis, the corresponding rotation matrix can be expressed as:

[0097]

[0098] In addition, find the translation vector between the two vectors:

[0099]

[0100] Therefore, we can get:

[0101]

[0102] The three driving heights of the P joint satisfy h1=h2=h3=h, and the three bevel angles of the connecting rod satisfy α1=α2=α3=α.

[0103] Therefore, the motion of the end effector can be represented by:

[0104]

[0105] Among them, (a) represents the translation along the z direction, (b) represents the rotation around the x-axis of the parasitic motion along the y direction, and (c) represents the rotation around the y-axis along the x direction.

[0106] Furthermore, the four-DOF serial robot is analyzed through discrete workspace analysis, and DH parameter design and workspace analysis are performed using Matlabrobotic toolbox. The basic kinematic configuration of 4R+2R1T is as follows: Figure 4 Its DH parameters are shown in the following table:

[0107]

[0108]

[0109] The workspace is analyzed by Monte Carlo method, and the results are as follows: Figure 5 shown.

[0110] Furthermore, the global force transfer coefficient is calculated in step 5 to obtain the hybrid robot structure, including: the input transfer index represents the power coefficient between the input torsion and the related transfer wrench, and the input motion / force transferability of the i-th limb can be expressed as:

[0111]

[0112] The denominator and molecules are the actual power and potential maximum power of the input component respectively. Consider You can get:

[0113] λ i =|sinα i |(i=1,2,3)

[0114] For an integrated parallel manipulator, the minimum value of λi is used to evaluate the input transmittance of the entire manipulator:

[0115] λ=min(λ i )(i=1,2,3)

[0116] λ defines the input transmission index indicators and gives their physical meanings and mathematical expressions.

[0117] Furthermore, the hierarchical optimization design method based on the PSO optimization algorithm includes:

[0118] The parameter design problem of the mechanism can be summarized as: given the task workspace and constraints, to achieve the optimal scale and structural parameters. The design parameters that need to be determined during optimization include:

[0119] (1) Dimensional parameters: geometric parameters of the base and end mount, working plane and global coordinate system

[0120] (3) Structural parameters: outer diameter and wall thickness of the swing chain and intermediate rod.

[0121] Considering the relationship between different performance indicators and design variables, and combining the system model with the design goals at different stages, a hierarchical optimization design process is implemented, such as Figure 6 shown.

[0122] To achieve the above object, according to one aspect of the present invention, various modules are provided:

[0123] 1. PUU parallel module: The parallel module is mainly used to improve the dexterity during grinding and polishing. It includes three branches, each of which has a P mobile joint and 4 R rotational joints. The axes of the four R joints and the two U joints in the i-th branch are represented by ri2, ri3, ri4 and ri5. PUUPM satisfies the following geometric constraints. The prismatic joint of each branch is collinear with the axis ri2. The axis ri2 and the axis ri5 intersect at point Di. The angle θ between the axis ri2 and the fixed platform is equal to the angle between the axis ri5 and the movable platform. The axis ri3 is parallel to the axis ri4. Pi1 represents the direction of the prismatic joint. Ui represents the U-shaped joint close to the prismatic joint. The plane formed by the intersection point Di of each branch is called the constraint plane s. The axis ri2 and the axis ri5 are symmetrical around the constraint plane s.

[0124] 2. Robotic arm module: The robot arm is mainly used to achieve large-scale positioning of the hybrid robot, hold the parallel terminal module for fine work, and ensure the overall size manufacturing requirements of large components. Designed as a 4-DOF robot arm, it can perform four movements (x, y, z, Rz). The flange at the end of the robot arm is tightly connected to the parallel terminal static platform through a fixed target seat. Its control system has an open communication interface, which can realize the individual control of the first 4 joints of the robot, and can be linked with the subsequently installed motors. Figure 7 Displays its hardware system composition.

[0125] The multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved parts provided by the present invention avoids the shortcomings of poor cantilever beam stiffness, accumulated structural open-loop errors, and low dexterity due to large inertia in the structure of traditional grinding and polishing robots by hybridizing parallel and serial structures. By selecting a new 3-PUU mechanism with 2R1T degrees of freedom (U represents a universal joint, and P represents a translation mechanism), it is easier and cheaper to develop into applications and has better directional capabilities. The hierarchical optimization design based on this configuration design effectively achieves the comprehensive optimization of scale and structure. It meets the requirements of high precision, high stiffness, and high dexterity in curved surface grinding and polishing.

[0126] 1. Specific application fields or related products of the present invention.

[0127] The following are application examples provided to demonstrate the creativity and technical value of the technical solution of the present invention:

[0128] Application Example 1: Grinding and polishing of aircraft engine blades

[0129] In the manufacturing process of aircraft engine blades, the grinding and polishing of curved surface parts is very important. Traditional processing methods have problems such as low efficiency and poor precision. The multi-degree-of-freedom serial-parallel hybrid robot system of the present invention is used for blade grinding and polishing, which can give full play to its advantages of high rigidity, high dexterity and high precision.

[0130] The specific implementation process is as follows:

[0131] According to the shape and size of the blade, the parameters of the 1T2R parallel mechanism of the hybrid robot and the four-degree-of-freedom serial robot are designed and adjusted to ensure that the robot can accurately reach all parts of the blade. Through the control system, the robot's end effector grinds and polishes the blade according to the preset trajectory and force. During the processing, the robot's force control system is used to monitor and adjust the grinding force in real time to ensure the stability of the processing quality. Compared with traditional processing methods, the robot system of the present invention can significantly improve the processing accuracy and surface quality of the blade, while improving processing efficiency and reducing production costs.

[0132] Application Example 2: Complex Surface Parts Processing

[0133] For other parts with complex surfaces, such as automobile engine parts, aerospace parts, etc., the robot system of the present invention also has broad application prospects. Taking the automobile engine cylinder block as an example, its internal surface shape is complex and difficult to process. Using the hybrid robot system of the present invention for processing can achieve high-precision and high-flexibility processing operations. The specific steps are as follows: perform a three-dimensional scan of the automobile engine cylinder block to obtain its surface shape and size information. According to the scanning data, plan the robot's processing path and actions. Start the robot system to grind and polish the cylinder block according to the planned path. During the processing, monitor the robot's operating status and processing effect in real time, adjust parameters in time, and ensure processing quality. Through practical application, the robot system of the present invention can effectively solve the problems in the processing of complex surface parts and improve the quality and performance of products.

[0134] The application of multi-degree-of-freedom serial-parallel hybrid robot system on other complex curved surface parts has a significant effect. The robot system has the characteristics of high rigidity and high precision. It can accurately reach various parts of complex curved surface parts and realize precise grinding and polishing, thereby significantly improving the processing accuracy of parts. The real-time monitoring and adjustment of the grinding force by the force control system can ensure the stability of the processing quality, make the surface of the parts smoother and more uniform, and improve the surface quality. The combination of the four-degree-of-freedom serial robot and the 1T2R parallel mechanism enables the robot to adapt to complex curved surface parts of different shapes and sizes, and has stronger processing flexibility. Compared with traditional processing methods, this robot system can complete processing tasks quickly and accurately, greatly improving production efficiency. High-precision processing reduces scrap rate and rework rate, while efficient production reduces labor and time costs, thereby reducing overall production costs.

[0135] For example, in the processing of automotive engine parts, the robot system can effectively process complex curved surface parts such as engine blocks and cylinder heads, improving the performance and reliability of these parts. In the processing of aerospace parts, it can ensure the accuracy and quality of parts to meet the high requirements of the aerospace field.

[0136] In short, the application of multi-degree-of-freedom serial-parallel hybrid robot systems on other complex curved parts has significant effects and can bring many advantages to related industries.

[0137] 2. Relevant evidence of the technical effects obtained by the embodiments of the present invention.

[0138] The following is relevant evidence of the technical effects obtained by the embodiments of the present invention, which is described in detail in combination with the data, charts, etc. of the test process:

[0139] 1. Kinematic Analysis Data

[0140] The configuration of the four-DOF serial robot was determined by kinematic analysis of the hybrid robot. Matlab robotic toolbox was used to design DH parameters and analyze the workspace, and the Monte Carlo method was used to analyze its workspace. Figure 5 As shown, it can be clearly seen from the figure that the robot's workspace distribution meets the requirement of 1m diameter and can effectively cover the required processing range, proving the accuracy and reliability of the robot in motion positioning.

[0141] 2. Calculation of force transfer coefficient

[0142] When calculating the global force transfer coefficient, the input motion / force transferability of the i-th limb is calculated according to the definition of the input transfer index. The specific calculation formula is: Among them, the denominator and numerator are the actual power and potential maximum power of the input component respectively. Considering the mutual coupling of the three limbs, we can get: For integrated parallel manipulators, λ i The minimum value of is used to evaluate the input transmission performance of the entire robot: Through the above calculations, relevant data for evaluating the input transmission performance of the entire robot are obtained, such as the values ​​of and . These data indicate that the hybrid robot is efficient and stable in force transmission and can ensure the force control accuracy during the machining process.

[0143] 3. Hierarchical optimization design results

[0144] Based on the PSO optimization algorithm, hierarchical optimization design is carried out to achieve the optimal scale and structural parameters given the task workspace and constraints. The design parameters that need to be determined during optimization include scale parameters (geometric parameters of the base and end seat, working plane and global coordinate system) and structural parameters (outer diameter and wall thickness of the swing branch chain and intermediate rod). Figure 6 As shown in the figure, the hierarchical optimization design process starts with the preliminary selection of structural parameters, and finally obtains the optimal scale parameters and optimal structural parameters through scale synthesis and structural parameter PSO optimization. The result of the optimization design is determined by judging whether it meets the high-speed dexterity requirements and whether it is consistent with the preliminary structure. The optimized design parameters can enable the robot to have better performance in force-controlled grinding and polishing of curved parts, such as higher stiffness, dexterity and precision.

[0145] 4. Software simulation effect

[0146] Through software simulation, the working process of the hybrid robot in the force-controlled grinding and polishing of curved surface parts was simulated. As shown in the figure (relevant pictures or schematic diagrams of software simulation can be inserted here), the simulation results show that the robot can accurately move according to the preset trajectory and can adjust the grinding force in real time to ensure the processing quality. At the same time, the simulation also shows the flexibility and adaptability of the robot in dealing with complex surfaces. It can adjust the posture and force direction in time according to the shape and changes of the surface to ensure the uniformity and accuracy of processing.

[0147] In summary, through the data, charts and software simulation effects of the above test process, it is fully proved that the multi-degree-of-freedom serial-parallel hybrid robot system of the present invention has the technical effects of high rigidity, high dexterity and high precision in the force-controlled grinding and polishing of curved parts, which can meet the needs of practical applications and provide an efficient and reliable solution for the processing of curved parts.

[0148] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0149] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A design method for a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts, characterized in that: The following steps are involved: Step 1: The hybrid grinding and polishing robot includes two parts: a 1T2R parallel mechanism and a four-degree-of-freedom serial robot. The 1T2R configuration is synthesized based on geometric algebra analysis. Step 2: Determine the number of 3 degrees of freedom of the 1T2R parallel mechanism and adopt a 3-PUU configuration, which consists of a movable platform B1B2B3, a fixed platform A1A2A3 and three identical PUU branches; each U-shaped joint consists of two vertically intersecting rotation joints; analyze the kinematics of the 3-PUU configuration based on the screw theory constraint; Step 3: Determine the configuration of the four-degree-of-freedom serial robot. Determine that the robot contains four joints and performs four movements of x, y, z, and Rz. The first three joints are responsible for positioning, and the fourth joint performs Rz movement. Through discrete workspace analysis, the DH parameters require that its workspace diameter is 1m. Step 4: derive the actuator size required for curved surface grinding and polishing of blades, calculate the global force transfer coefficient, and obtain the hybrid robot structure; Step 5: Based on the actual physical constraints and workspace constraints, the global force transfer coefficient and the global dexterity index are optimized by PSO optimization algorithm, and the hierarchical optimization design is realized with Pareto optimality as the goal. The global force transfer coefficient is calculated in step 4 to obtain the hybrid robot structure, including: the input transfer index represents the power coefficient between the input torsion and the related transfer wrench, and the input motion / force transferability of the i-th limb is expressed as: The denominator |S Ii °S Ti | max and molecule|S Ii °S Ti | are the actual power and potential maximum power of the input components respectively; |S li °S Ti | max =|sinα i | max =1, we get: l i =∣sina i ∣(i=1,2,3) For an integrated parallel manipulator, the minimum value of λi is used to evaluate the input transmittance of the entire manipulator: λ=min(λ i (i=1,2,3) λ defines the input transmission index indicators and gives their physical meanings and mathematical expressions; In step 5, a hierarchical optimization design is performed based on the PSO optimization algorithm. Given the task workspace and constraints, the optimal scale and structural parameters are achieved. The design parameters that need to be determined during optimization include: (1) Scale parameters: geometric parameters of the base and end seat, working plane and global coordinate system; (3) Structural parameters: outer diameter and wall thickness of the swing chain and intermediate rod; According to the relationship between different performance indicators and design variables, the system model is combined with the design goals of different stages to achieve a hierarchical optimization design process.

2. The design method of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts according to claim 1, characterized in that: The step 1 is based on geometric algebraic analysis of 1T2R configuration synthesis and includes: For a 1T2R non-redundant drive parallel mechanism with a certain axis, its output degrees of freedom are expressed by geometric algebra as follows: S m =A1∩A2∩A3=G1∧G2∧G3=(e1)∧(c α e2-s α e3+b 2,1,m e4)∧(s α e5+c α e6) Among them, A i (i=1,2,3) represents the kinematic subspace of the kinematic chain, S m represents the motion subspace of the dynamic platform of the mechanism; G i (i=1,2,3) represents the output degree of freedom of the 1T2R parallel mechanism, e represents the basis vector of the vector space, s and c represent the sin and cos functions, α represents the rotation angle around a certain axis in space, and b represents the second output degree of freedom; Based on the above design, a basic mechanism with two rotations and one translation is determined to provide guidance for the selection of the grinding and polishing hybrid robot; among them, a new 3-PUU architecture with 1T2R degrees of freedom is selected (U represents the universal joint, and P represents the translation mechanism).

3. The design method of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts according to claim 1, characterized in that: The second step of analyzing the kinematics of the 3-PUU configuration based on the screw theory constraint includes: Where R and T are the rotation matrix and translation vector between the local coordinate system and the global coordinate system respectively; S is the virtual screw expressed in the local coordinate system; The motion of the end effector is represented by: Among them, (a) represents the translation along the z direction, (b) represents the rotation around the x-axis of the parasitic motion along the y direction, (c) represents the rotation around the y-axis along the x direction, and α represents the rotation angle around a certain axis in space.

4. The design method of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts according to claim 1, characterized in that: In the step three, the four-degree-of-freedom serial robot is analyzed by discrete workspace analysis, DH parameter design and workspace analysis are performed using MATLAB robotic toolbox, and its workspace is analyzed by the Monte Carlo method.

5. A hybrid robot system designed by the design method of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts as claimed in any one of claims 1 to 4, characterized in that: It consists of two parts: 1T2R parallel mechanism and four-degree-of-freedom serial robot; The 1T2R parallel mechanism consists of a movable platform B1B2B3, a fixed platform A1A2A3 and three identical PUU branches; each U-shaped joint consists of two vertically intersecting rotary joints; The four-degree-of-freedom serial robot contains four joints and can perform four movements: x, y, z, and Rz. The first three joints are responsible for positioning, and the fourth joint performs Rz movement.

6. A computer device, characterized in that: The computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the design method of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts as described in any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the processor executes the steps of the design method of a multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts as described in any one of claims 1 to 4.

8. An information data processing terminal, characterized in that: The information data processing terminal includes the multi-degree-of-freedom serial-parallel hybrid robot system for force-controlled grinding and polishing of curved surface parts as described in claim 5.

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