A method for constructing a parallel robot

Abstract

The present invention provides a parallel robot construction method, comprising: constructing a parallel mechanism, the parallel mechanism comprising a basic static platform and a dynamic platform, the basic static platform being connected to the dynamic platform through a branch chain; based on the constructed parallel mechanism, establishing the kinematic and dynamic models of the parallel robot through a closed-loop vector law and a virtual work principle; obtaining the optimization objectives and constraints in the kinematic and dynamic models according to the motion characteristics of the parallel mechanism, and optimizing the scale parameters and structural parameters of the parallel mechanism; obtaining the control model of the parallel robot based on the optimized kinematic and dynamic models, controlling the parallel robot using the driving parameters in the control model, and completing the construction of the parallel robot. The present invention analyzes the kinematic and dynamic models of the parallel robot, and optimizes the structural parameters using an optimization algorithm according to performance evaluation indicators, so that the control is more accurate and efficient.

Description

Technical Field

[0001] The present invention relates to the field of robotics technology, and in particular to a method for constructing a parallel robot. Background Art

[0002] Industrial robots will free workers from single physical labor and effectively improve production efficiency and quality. Therefore, they are widely used in various fields of industrial production. According to the mechanical structure, industrial robots can be divided into serial robots and parallel robots, such as SCARA serial robots and DELTA parallel robots. Serial robots are open kinematic chains formed by a series of connecting rods connected in series through rotating joints or moving joints. Parallel robots are robots with a closed-loop structure formed by connecting at least two or more branches that can move independently between their fixed platform and moving platform. Among them, parallel robots are mostly used in food packaging, sorting, and pharmaceutical production for their high precision, high rigidity, small space occupation, and small cumulative error. Therefore, it is of great research significance to analyze the structure of parallel robots and obtain the structural parameters that optimize their comprehensive performance.

[0003] In summary, how to overcome the above-mentioned defects is a problem that those skilled in the art need to solve urgently. Summary of the invention

[0004] In response to the above-mentioned problems and needs, this solution proposes a parallel robot construction method, which can solve the above-mentioned technical problems by adopting the following technical solutions.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for constructing a parallel robot, comprising: constructing a parallel mechanism, wherein the parallel mechanism comprises a basic static platform and a dynamic platform, wherein the basic static platform is connected to the dynamic platform via a branch chain;

[0006] Based on the constructed parallel mechanism, the kinematic and dynamic models of the parallel robot are established through the closed-loop vector law and the principle of virtual work;

[0007] According to the motion characteristics of the parallel mechanism, the optimization objectives and constraints in the kinematic and dynamic models are obtained, and the scale parameters and structural parameters of the parallel mechanism are optimized;

[0008] A control model of the parallel robot is obtained based on the optimized kinematic and dynamic models, and the parallel robot is controlled using the driving parameters in the control model to complete the construction of the parallel robot.

[0009] Furthermore, the construction of the parallel mechanism specifically includes: establishing a basic static platform, the basic static platform is provided with a plurality of driving devices; the basic static platform and the moving platform are connected through two branch chains, each branch chain includes an active arm and a driven arm, one end of the active arm is connected to the driving device through a rotating joint, the other end of the active arm is connected in series with the driven arm through an elbow joint, the driven arm is connected to the moving platform through a rotating pair, and the moving platform moves within a two-dimensional plane; a coordinate system O is established on the moving platform and the basic static platform of the parallel robot. x,y .

[0010] Furthermore, the specific steps of establishing the kinematic and dynamic models of the parallel robot based on the constructed parallel mechanism through the closed-loop vector law and the principle of virtual work include:

[0011] First, take the center of the basic static platform as the origin O, establish a two-dimensional motion coordinate system, and obtain the joint angle variables θ corresponding to the revolute joint and the elbow joint. 1i and θ 2i , get the joint vector

[0012] According to the closed-loop position formula: P-sgn(i)dd1-t1w i =t2m i , calculate the terminal pose matrix corresponding to the position p of the terminal actuator on the moving platform in, d represents the distance between the revolute joint and the origin, d1 represents the unit vector of the distance between the revolute joint and the origin, and w i =(cosθ 1i sinθ 1i ) T Unit vector representing the length of the active arm, m i =(cosθ 2i sinθ 2i ) 1 The unit vector representing the rod length of the slave arm, t1 and t2 represent the rod lengths of the master arm and the slave arm, respectively;

[0013] By taking the derivative of the closed-loop position formula with respect to time, we can obtain the moving speed u of the moving platform and the speed mapping model of the parallel mechanism, θ 1i =J*u, where J represents the Jacobian matrix, from which the singular bit information can be obtained;

[0014] According to the calculation formula of virtual work principle: Where ε represents the torque of the revolute joint, a represents the acceleration of the moving platform, and d2 = (0 1) t , m represents the mass of the moving platform, I Arepresents the moment of inertia of the active arm shaft, ε Ag The gravity moment of the active arm about the rotating shaft gives the inverse dynamics formula of the parallel mechanism: ε=I a (m / I A J -T +J)a+I A f(u)+mgJ -T d2+ε Ag .

[0015] Furthermore, obtaining the optimization objectives and constraints in the kinematic and dynamic models according to the motion characteristics of the parallel mechanism is achieved by analyzing the kinematic and dynamic performance indicators of the parallel robot and selecting and constructing reasonable performance evaluation indicators.

[0016] Furthermore, the specific steps of selecting and constructing reasonable performance evaluation indicators include:

[0017] The singular bit information obtained from the Jacobian matrix obtains the condition number index representing the stability and accuracy of the Jacobian matrix inversion. Among them, τ max It is used to describe the maximum magnification between the input and output transfer of the parallel mechanism to control the minimum singular value index corresponding to the maximum value of the running speed of the end, τ min Indicates the maximum singular value index corresponding to the minimum singular value index;

[0018] Calculation indicators Analyze the speed of the mechanism and obtain the global kinematic performance index Among them, ω is The weighting factor of

[0019] According to the method of constructing global kinematic performance index, a global dynamics evaluation index that can reflect the mean and deviation of the singular values ​​of the driving force matrix is ​​constructed: Among them, τ max is the maximum value of the maximum singular value of the system's hybrid moment matrix;

[0020] The optimization objective function in the kinematic and dynamic models is obtained from the obtained performance evaluation indicators.

[0021] Furthermore, the specific steps of optimizing the dimensional parameters and structural parameters of the parallel mechanism include:

[0022] Firstly, the working space parameters, load capacity parameters, grasping frequency and maximum acceleration of the parallel robot are obtained;

[0023] The obtained performance evaluation index is used to analyze the space occupation ratio constraint, transmission angle constraint and assembly condition constraint of the parallel robot structure design;

[0024] Determine the motor and reducer parameters of the parallel robot, and use the optimization method based on the improved genetic algorithm to perform multi-objective parameter optimization with kinematic and dynamic performance evaluation indicators as the objective function. Use the normalized summation method to select the optimal solution from the optimization solution set to obtain the basic scale parameters of the parallel robot.

[0025] According to the above optimization results, calculate whether the equivalent load moment of inertia of the parallel robot matches the corresponding motor rotor inertia, and judge whether the torque, speed and power of the selected motor can meet the requirements of typical grasping operations. If so, output the optimization results, otherwise modify the motor and reducer parameters of the parallel robot.

[0026] A parallel robot construction system is implemented by the above-mentioned parallel robot construction method, characterized in that it includes: a mechanism construction module, a model building module, a parameter optimization module and a drive control module;

[0027] The mechanism building module is used to build a parallel mechanism, and the parallel mechanism includes a basic static platform and a dynamic platform, and the basic static platform is connected to the dynamic platform through a branch chain;

[0028] The model building module is used to build the kinematic and dynamic models of the parallel robot based on the constructed parallel mechanism through the closed-loop vector law and the principle of virtual work;

[0029] The parameter optimization module is used to obtain the optimization objectives and constraints in the kinematic and dynamic models according to the motion characteristics of the parallel mechanism, and to optimize the scale parameters and structural parameters of the parallel mechanism;

[0030] The drive control module is used to obtain a control model of the parallel robot based on the optimized kinematic and dynamic models, and to control the parallel robot using the drive parameters in the control model to complete the construction of the parallel robot.

[0031] It can be seen from the above technical solutions that the beneficial effects of the present invention are as follows: the present invention analyzes the kinematic and dynamic models of the parallel robot and optimizes the structural parameters using an optimization algorithm according to performance evaluation indicators, thereby making the control more precise and efficient.

[0032] In addition to the objects, features and advantages described above, the best embodiments for implementing the present invention will be described in more detail below with reference to the accompanying drawings so that the features and advantages of the present invention can be easily understood. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments of the present invention or the description of the prior art, wherein the drawings are only used to show some embodiments of the present invention, rather than limiting all embodiments of the present invention thereto.

[0034] Figure 1 It is a schematic diagram of the specific steps of a method for constructing a parallel robot in the present invention.

[0035] Figure 2 Schematic diagram of the specific steps of step S4 in this embodiment.

[0036] Figure 3 This is a schematic diagram of the specific steps of selecting and constructing reasonable performance evaluation indicators in this embodiment.

[0037] Figure 4 Schematic diagram of specific steps for optimizing the dimensional parameters and structural parameters of the parallel mechanism in this embodiment.

[0038] Figure 5 The figure is a schematic diagram of the composition structure of a parallel robot construction system in the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the technical solution of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described in conjunction with the drawings of specific embodiments of the present invention. The same figure marks in the drawings represent the same parts. It should be noted that the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Parallel robots are widely used in food packaging, sorting, and pharmaceutical production. It is of great research significance to analyze the structure of parallel robots and obtain structural parameters that optimize their comprehensive performance. Therefore, the present application discloses a method for constructing a parallel robot that analyzes the kinematic and dynamic models of the parallel robot and optimizes the structural parameters using an optimization algorithm according to performance evaluation indicators, thereby making the control more precise and efficient. Figure 1 As shown, the specific steps of the method are as follows:

[0041] Step S1: construct a parallel mechanism, wherein the parallel mechanism comprises a basic static platform and a dynamic platform, and the basic static platform is connected to the dynamic platform through a branch chain.

[0042] The construction of the parallel mechanism specifically includes: establishing a basic static platform, the basic static platform is provided with a plurality of driving devices; the basic static platform and the moving platform are connected by two branch chains, each branch chain includes an active arm and a driven arm, one end of the active arm is connected to the driving device through a rotating joint, the other end of the active arm is connected in series with the driven arm through an elbow joint, the driven arm is connected to the moving platform through a rotating pair, and the moving platform moves within a two-dimensional plane; a coordinate system O is established on the moving platform and the basic static platform of the parallel robot. x,y .

[0043] In this embodiment, taking the structure of a two-degree-of-freedom parallel robot as an example, the two active arms will continuously rotate in the same or opposite directions when driven, the active arms drive the driven rod to move, and the two parallel motion branches jointly control the movement of the moving platform within the two-dimensional plane.

[0044] Step S2: Based on the constructed parallel mechanism, the kinematic and dynamic models of the parallel robot are established through the closed-loop vector law and the principle of virtual work.

[0045] Specifically, Figure 2 As shown, the specific steps of establishing the kinematic and dynamic models of the parallel robot based on the constructed parallel mechanism through the closed-loop vector law and the principle of virtual work include:

[0046] Step S21: First, take the center of the basic static platform as the origin O, establish a two-dimensional motion coordinate system, and obtain the joint angle variable θ corresponding to the revolute joint and the elbow joint 1i and θ 2i , get the joint vector

[0047] Step S22: According to the closed-loop position formula: P-sgn(i)dd1-t1w i =t2m i , calculate the terminal pose matrix corresponding to the position p of the terminal actuator on the moving platform in, d represents the distance between the revolute joint and the origin, d1 represents the unit vector of the distance between the revolute joint and the origin, and w i =(cosθ 1i sinθ 1i ) T Unit vector representing the length of the active arm, m i =(cosθ 2i sinθ 2i ) T The unit vector representing the rod length of the slave arm, t1 and t2 represent the rod lengths of the master arm and the slave arm, respectively;

[0048] Step S23: Derivative the closed-loop position formula with respect to time to obtain the moving speed u of the moving platform, and obtain the speed mapping model of the parallel mechanism, θ 1i =J*u, where J represents the Jacobian matrix, from which the singular bit information can be obtained;

[0049] Step S24: Calculate the formula according to the virtual work principle: Wherein, ε represents the torque of the revolute joint, a represents the acceleration of the moving platform, and d2=(01) T , m represents the mass of the moving platform, I A represents the moment of inertia of the active arm shaft, ε Ag The gravity moment of the active arm about the rotating shaft gives the inverse dynamics formula of the parallel mechanism: ε=I A (m / I A J -t +J)a+I A f(u)+mgJ -t d2+ε Ag .

[0050] Step S3: According to the motion characteristics of the parallel mechanism, the optimization objectives and constraints in the kinematic and dynamic models are obtained, and the scale parameters and structural parameters of the parallel mechanism are optimized.

[0051] In this embodiment, the structural dimensions are the arm length, rod length, etc., the workspace parameters are the range of the motion space, and the limit information is the position limit of the active arm rotation angle. Based on these scale information, parameter information and limit information, the kinematic and dynamic models of the parallel robot can be analyzed and optimized.

[0052] Specifically, the optimization objectives and constraints in the kinematic and dynamic models are obtained according to the motion characteristics of the parallel mechanism, which is achieved by analyzing the kinematic and dynamic performance indicators of the parallel robot, selecting and constructing reasonable performance evaluation indicators, such as Figure 3 As shown, the specific steps of selecting and constructing reasonable performance evaluation indicators include:

[0053] a. The singular bit information obtained from the Jacobian matrix obtains the condition number index representing the stability and accuracy of the Jacobian matrix inversion Among them, τ max It is used to describe the maximum magnification between the input and output transfer of the parallel mechanism to control the minimum singular value index corresponding to the maximum value of the running speed of the end, τ min Indicates the maximum singular value index corresponding to the minimum singular value index;

[0054] b. Calculation indicators Analyze the speed of the mechanism and obtain the global kinematic performance index Among them, ω is The weighting factor of

[0055] c. Based on the method of constructing global kinematic performance indicators, a global dynamics evaluation index that can reflect the mean and deviation of the singular values ​​of the driving force matrix is ​​constructed: Among them, τ max is the maximum value of the maximum singular value of the system hybrid moment matrix, where the kinematic global performance index is the kinematic performance optimization objective function, and the dynamic global performance index is the dynamic performance optimization objective function;

[0056] d. Obtain the optimization objective function in the kinematic and dynamic models based on the obtained performance evaluation indicators.

[0057] More specifically, if Figure 4 The content shown, the specific steps of optimizing the dimensional parameters and structural parameters of the parallel mechanism include:

[0058] a. First, obtain the workspace parameters, load capacity parameters, grasping frequency and maximum acceleration of the parallel robot;

[0059] b. Analyzing the space ratio constraint, transmission angle constraint and assembly condition constraint of the parallel robot structure design based on the obtained performance evaluation index;

[0060] c. Determine the motor and reducer parameters of the parallel robot, and use the optimization method based on the improved genetic algorithm to perform multi-objective parameter optimization with kinematic and dynamic performance evaluation indicators as the objective function. Use the normalized summation method to select the optimal solution from the optimization solution set to obtain the basic scale parameters of the parallel robot;

[0061] d. Based on the above optimization results, calculate whether the equivalent load moment of inertia of the parallel robot matches the corresponding motor rotor inertia, and determine whether the torque, speed and power of the selected motor can meet the requirements of typical grasping operations. If so, output the optimization results; otherwise, modify the motor and reducer parameters of the parallel robot.

[0062] In this embodiment, the specific steps of performing multi-objective parameter optimization based on the optimization method based on the improved genetic algorithm with the kinematic and dynamic performance evaluation index as the objective function to obtain the basic scale parameters of the parallel robot include: initializing the population; calculating the non-dominated sorting and crowding; performing selection, crossover and mutation update calculations, and merging the population according to the calculation results; calculating the non-dominated sorting and crowding again, generating a new population, and judging whether the number of iterations has been reached, and terminating if so, otherwise continuing the update calculation.

[0063] Step S4: Obtain a control model of the parallel robot based on the optimized kinematic and dynamic models, and use the driving parameters in the control model to control the parallel robot to complete the construction of the parallel robot.

[0064] like Figure 5 As shown, a parallel robot construction system is implemented by adopting the above-mentioned parallel robot construction method, characterized in that it includes: a mechanism construction module, a model building module, a parameter optimization module and a drive control module;

[0065] The mechanism building module is used to build a parallel mechanism, and the parallel mechanism includes a basic static platform and a dynamic platform, and the basic static platform is connected to the dynamic platform through a branch chain;

[0066] The model building module is used to build the kinematic and dynamic models of the parallel robot based on the constructed parallel mechanism through the closed-loop vector law and the principle of virtual work;

[0067] The parameter optimization module is used to obtain the optimization objectives and constraints in the kinematic and dynamic models according to the motion characteristics of the parallel mechanism, and to optimize the scale parameters and structural parameters of the parallel mechanism;

[0068] The drive control module is used to obtain a control model of the parallel robot based on the optimized kinematic and dynamic models, and to control the parallel robot using the drive parameters in the control model to complete the construction of the parallel robot.

[0069] It should be noted that the embodiments described in the present invention are only preferred ways to implement the present invention, and any obvious modifications that belong to the overall concept of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for constructing a parallel robot, characterized in that: The specific steps are as follows: Constructing a parallel mechanism, the parallel mechanism comprising a basic static platform and a dynamic platform, the basic static platform being connected to the dynamic platform via a branch chain; Based on the constructed parallel mechanism, the kinematic and dynamic models of the parallel robot are established through the closed-loop vector law and the principle of virtual work; According to the motion characteristics of the parallel mechanism, the optimization objectives and constraints in the kinematic and dynamic models are obtained, and the scale parameters and structural parameters of the parallel mechanism are optimized; A control model of the parallel robot is obtained based on the optimized kinematic and dynamic models, and the parallel robot is controlled by using the driving parameters in the control model to complete the construction of the parallel robot; The specific steps of establishing the kinematic and dynamic models of the parallel robot based on the constructed parallel mechanism through the closed-loop vector law and the principle of virtual work include: First, take the center of the basic static platform as the origin O to establish a two-dimensional motion coordinate system, and obtain the joint angle variables corresponding to the revolute joint and the elbow joint. and , get the joint vector ; According to the closed-loop position formula: P-sgn(i)dd1-t1w i =t2m i , calculate the terminal pose matrix corresponding to the position p of the terminal actuator on the moving platform ,in, , d represents the distance between the revolute joint and the origin, represents the unit vector of the distance between the revolute joint and the origin, is the unit vector representing the length of the active arm, is the unit vector representing the length of the slave arm, and Respectively represent the rod length of the active arm and the driven arm; The closed-loop position formula is differentiated with respect to time to obtain the moving speed u of the moving platform, and the speed mapping model of the parallel mechanism is obtained. , where J represents the Jacobian matrix, from which the singular bit information can be obtained; According to the calculation formula of virtual work principle: ,in, represents the torque of the revolute joint, a represents the acceleration of the moving platform, , m represents the mass of the moving platform, represents the moment of inertia of the active arm shaft, The gravity moment of the active arm about the rotating shaft gives the inverse dynamics formula of the parallel mechanism: .

2. The parallel robot construction method according to claim 1, characterized in that: The construction of the parallel mechanism specifically includes: establishing a basic static platform, the basic static platform is provided with a plurality of driving devices; the basic static platform and the moving platform are connected by two branch chains, each branch chain includes an active arm and a driven arm, one end of the active arm is connected to the driving device through a rotating joint, the other end of the active arm is connected in series with the driven arm through an elbow joint, the driven arm is connected to the moving platform through a rotating pair, and the moving platform moves within a two-dimensional plane; a coordinate system is established on the moving platform and the basic static platform of the parallel robot .

3. The parallel robot construction method according to claim 1, characterized in that: The acquisition of optimization objectives and constraints in the kinematic and dynamic models according to the motion characteristics of the parallel mechanism is achieved by analyzing the kinematic and dynamic performance indicators of the parallel robot and selecting and constructing reasonable performance evaluation indicators.

4. The parallel robot construction method according to claim 3, characterized in that: The specific steps of selecting and constructing reasonable performance evaluation indicators include: The singular bit information obtained from the Jacobian matrix obtains the condition number index representing the stability and accuracy of the Jacobian matrix inversion. ,in, It is used to describe the maximum magnification between the input and output transfer of the parallel mechanism to control the minimum singular value index corresponding to the maximum value of the running speed of the end. Indicates the maximum singular value index corresponding to the minimum singular value index; Calculation indicators Analyze the speed of the mechanism and obtain the global kinematic performance index , where ω is The weighting factor of According to the method of constructing global kinematic performance index, a global dynamics evaluation index that can reflect the mean and deviation of the singular values ​​of the driving force matrix is ​​constructed: ,in, is the maximum value of the maximum singular value of the system's hybrid moment matrix; The optimization objective function in the kinematic and dynamic models is obtained from the obtained performance evaluation indicators.

5. The parallel robot construction method according to claim 4, characterized in that: The specific steps of optimizing the dimensional parameters and structural parameters of the parallel mechanism include: Firstly, the working space parameters, load capacity parameters, grasping frequency and maximum acceleration of the parallel robot are obtained; The obtained performance evaluation index is used to analyze the space occupation ratio constraint, transmission angle constraint and assembly condition constraint of the parallel robot structure design; Determine the motor and reducer parameters of the parallel robot, and use the optimization method based on the improved genetic algorithm to perform multi-objective parameter optimization with kinematic and dynamic performance evaluation indicators as the objective function. Use the normalized summation method to select the optimal solution from the optimization solution set to obtain the basic scale parameters of the parallel robot. According to the above optimization results, calculate whether the equivalent load moment of inertia of the parallel robot matches the corresponding motor rotor inertia, and judge whether the torque, speed and power of the selected motor can meet the requirements of typical grasping operations. If so, output the optimization results, otherwise modify the motor and reducer parameters of the parallel robot.

6. A parallel robot construction system, implemented by the parallel robot construction method according to any one of claims 1 to 5, characterized in that: include: Mechanism construction module, model building module, parameter optimization module and drive control module; The mechanism building module is used to build a parallel mechanism, and the parallel mechanism includes a basic static platform and a dynamic platform, and the basic static platform is connected to the dynamic platform through a branch chain; The model building module is used to build the kinematic and dynamic models of the parallel robot based on the constructed parallel mechanism through the closed-loop vector law and the principle of virtual work; The parameter optimization module is used to obtain the optimization objectives and constraints in the kinematic and dynamic models according to the motion characteristics of the parallel mechanism, and to optimize the scale parameters and structural parameters of the parallel mechanism; The drive control module is used to obtain a control model of the parallel robot based on the optimized kinematic and dynamic models, and to control the parallel robot using the drive parameters in the control model to complete the construction of the parallel robot.

Images