Distributed cooperative position tracking control method for multi-rolls in roll bending

Abstract

The present invention discloses a distributed cooperative position tracking control method for multi-rolls in roll bending forming. [Solution] Based on knowledge of graph theory, a directed graph is used to describe the network topology structure of a multi-roll system, and each roll is considered as a node in the directed graph to determine the roll position tracking error system. A multi-roll distributed position tracking control method is designed based on distributed control theory. The stability of the control method is verified through simulation analysis. The present invention adopts a multi-roll distributed cooperative position tracking control method for roll bending, which has self-organized cooperative control capabilities and uses intelligent control technology to cooperatively control the relative positions of each roll, thereby achieving position control for each roll, with higher position control accuracy and more stable roll operation, strong robustness and flexibility, and easily meeting the bending requirements of a variety of section materials.

Description

[Technical Field]

[0001] The present invention relates to the technical field of distributed cooperative control, and more particularly to a method for distributed cooperative position tracking control of multi-rolls in roll bending. [Background technology]

[0002] Profile roll bending technology has played an important role in the development of China's industry. It is widely used in industries such as petroleum, shipbuilding, water conservancy, boilers, and aviation, and roll bending machines are key equipment for completing the roll bending process. Three-roll bending machines, including multi-roll machines, have particularly wide industrial applications. Three-roll bending machines currently in production and use in China typically require operators to manually adjust the relative position of the upper roll. This control method can lead to unintended manual adjustments and blind adjustments, resulting in poor roll bending accuracy. Furthermore, most of these control systems use open-loop control, which results in poor synchronization between the left and right lower rolls. Over time, the cumulative deviation between the two lower rolls continues to increase, making this method unsuitable for applications with strict precision requirements, such as aerospace. Therefore, to improve profile bending accuracy and achieve accurate control of each roll's position in the process flow, research is needed to develop coordinated control of the roll positions.

[0003] Therefore, to address the above-mentioned problems, the present invention designs a distributed cooperative position tracking control method for multi-rolls in roll bending, to realize the position control of each roll. Summary of the Invention

[0004] The objective of the present invention is to provide a distributed cooperative position tracking control method for multi-rolls in roll bending, which has self-organized cooperative control ability, and utilizes intelligent control technology to cooperatively control the relative positions of each roll, thereby realizing position control of each roll, with higher position control accuracy, more stable roll operation, strong robustness and flexibility, and easily achieving the bending requirements of various section materials.

[0005] To achieve the above object, the present invention provides a method for distributed cooperative position tracking control of multi-rolls in roll bending, which includes the following steps: Step S1: Consider each role as an intelligent entity (agent) and build a dynamic model of a single role. Step S2: Based on the knowledge of graph theory, in the multi-agent cooperative control, the communication network between the intelligent entities is abstracted into a topology form of information flow, and the network topology structure of the multi-role system is depicted using a directed graph, and each role is regarded as a node in the directed graph, and the role position tracking error system is determined; Step S3: Based on the distributed control theory, design a multi-role distributed position tracking control method, including the design of virtual control inputs and the design of actual control inputs; Step S4: Verify the stability and simulation analysis of the control method.

[0006] Preferably, in step S1, each role may be regarded as an intelligent entity i, and a dynamic model of a single role may be constructed as follows:

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[0007] Preferably, in step S2, based on the knowledge of graph theory, in the multi-intelligent entity cooperative control, the communication network between the intelligent entities is abstracted into a topology form of information flow, and a directed graph is used to depict the network topology structure of the multi-role system, and each role is regarded as a node in the directed graph, and the role position tracking error system e is calculated as shown below. i1 may be determined.

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[0008] Preferably, in step S3, a multi-role distributed position tracking control method is designed based on distributed control theory, and a virtual control input α i Specifically, the following may be designed: Step S311: Based on the position tracking error system of step S2, e i1 Differentiation is performed on

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[0009] Preferably, in step S3, a multi-role distributed position tracking control method is designed based on distributed control theory, and the actual control input u i Specifically, the following may be designed: Step S321: Observer estimation

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[0010] Preferably, in verifying the stability of the control method in step S4, unmodeled dynamics are considered.

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[0011] The present invention adopts a distributed cooperative position tracking control method for multi-rolls in roll bending, which has self-organized cooperative control ability, and utilizes intelligent control technology to cooperatively control the relative positions of each roll, thereby realizing position control of each roll, with higher position control accuracy and more stable roll operation, and with strong robustness and flexibility, which can easily meet the bending requirements of various sections.

[0012] The following will further describe the technical solutions of the present invention in detail with the accompanying drawings and examples. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an overall flowchart of a method for controlling the distributed and cooperative position tracking of multiple rolls in roll bending according to the present invention; [Figure 2] 1 shows the communication relationship between rolls provided by the simulation verification of the distributed cooperative position tracking control method for multi-rolls in roll bending forming of the present invention. [Figure 3] 1 shows the horizontal displacement error curves of each roll provided by the simulation verification of the distributed cooperative multi-roll position tracking control method for roll bending according to the present invention. [Figure 4] 1 shows vertical displacement error curves of each roll provided by simulation verification of the method for distributed cooperative position tracking control of multiple rolls in roll bending according to the present invention. [Figure 5] 1 shows the horizontal control input curves of each roll provided by the simulation verification of the distributed and coordinated multi-roll position tracking control method for roll bending according to the present invention. [Figure 6] 1 shows vertical control input curves for each roll provided by simulation verification of the method for distributed and coordinated multi-roll position tracking control of roll bending according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] In order to make the objectives, technical solutions and advantages disclosed in the embodiments of the present invention more clearly understood, the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for illustrating the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0015] (Example) Due to the limited number of steps that a numerical control system can drive a machine tool, it is impossible to completely achieve infinite approximation of the outer shape of a variable curvature section when forming a section part with continuously changing curvature. Therefore, to ensure that the geometric approximation error of the section outer contour is within a reasonable range, the segment method is used to achieve variable curvature roll bending of the section. The segment method divides the section into a finite number of micro-segments according to the specified section forming requirements, and each micro-segment can be considered to have an equal curvature. The forming radius of each arc segment is determined. Furthermore, by precisely controlling the displacement of each roll, the section can achieve precise feed within each arc segment.

[0016] This invention uses a "3+1" roll bending machine. Its main components include an upper roll, left and right lower rolls, a servo cylinder, a lower center roll, left and right side rolls, and a support frame. The upper roll is fixed to the support frame. The left and right lower rolls are driven by a servo cylinder to perform an arc-shaped motion along the center pin shaft. The profile is placed between the upper and lower rolls. The left and right lower rolls control their position according to the roll radius, and simultaneously rotate to feed the profile one or more times. The lower center roll functions as a measuring roll during roll bending of L-shaped non-closed profiles, reducing irregular deformations such as twist deformation, cross-sectional angle changes, and unstable wrinkles. In actual working conditions, the profile thickness and material properties are combined, while fully considering the springback compensation amount for each arc segment, to finally form the profile into the specified curvature.

[0017] This invention provides a method for distributed cooperative position tracking control of multiple rolls in roll bending, which is based on the theory of cooperative control of intelligent objects and combined with a backstep control method to achieve high-precision position control of each roll. Here, the control goal is to design a distributed position tracking controller for each roll as follows, so that the left and right lower rolls can move accurately under the action of the controller, achieve high-precision position tracking control, and maintain a desired relative distance from the upper roll:

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[0018] As shown in FIG. 1, the bending multi-roll distributed cooperative position tracking control method specifically includes the following steps: Step S1: Build a dynamic model of a single roll. Because each of the three rolls has its own independent drive system, each roll can be considered an intelligent entity, and multi-roll position control can be considered a position tracking control problem for multiple intelligent entities. Through roll dynamics research, intelligent entity i (i=1, 2, 3) with a lower triangular structure is used to describe the roll dynamics model using a nonlinear system as follows:

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[0019] Step S2: Based on the knowledge of graph theory, determine the roll position tracking error system. Based on the knowledge of graph theory, in the cooperative control of multiple intelligent entities, the communication network between the intelligent entities is abstracted into a topology form of information flow, and the network topology structure of the multi-role system is depicted using a directed graph. Each role is regarded as a node in the directed graph, and the position tracking error system e of role (intelligent entity i) is calculated as follows: i1 Confirm.

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[0020] Step S3: Based on the distributed control theory, a multi-role distributed position tracking control method is designed. Step S31: Virtual control input α i Design. Step S311: Based on the position tracking error system of step S2, e i1 Perform the differential operation of .

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[0021] Step S32: Actual control input u i Design. Step S321: Observer estimation

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[0022] Step S4: Verify the stability and simulation analysis of the above control method. Step S41: Prove stability. Hypothesis 1: Unmodeled dynamics

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[0023] The simulation results show that Figures 3 and 4 show the horizontal and vertical displacement error curves of each roll. Figures 5 and 6 show the horizontal and vertical control input curves of each roll. Each roll can achieve high-precision position tracking, and the tracking error is bounded and stable. The control input curves of each roll are very smooth.

[0024] Therefore, the present invention adopts a distributed cooperative position tracking control method for multi-rolls in roll bending, which has self-organized cooperative control ability, and utilizes intelligent control technology to cooperatively control the relative positions of each roll, thereby realizing position control of each roll, which further improves the position control accuracy, makes the roll operation more stable, has strong robustness and flexibility, and can easily meet the roll bending requirements of various profiles.

[0025] Finally, it should be noted that the above embodiments only illustrate the technical solutions of the present invention, but do not limit it, and although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot make the modified technical solutions depart from the spirit and scope of the technical solutions of the present invention.

Claims

[Claim 1] A method for distributed cooperative position tracking control of multiple rolls in a roll bending machine of a multi-roll type including three rolls forming a lower triangular structure, comprising: Step S1: Consider each role as an intelligent entity and construct a dynamic model of a single role; Step S2: Based on the knowledge of graph theory, in the cooperative control of multiple intelligent entities, the communication network between the intelligent entities is abstracted into a topology form of information flow, and the network topology structure of the multi-role system is depicted using a directed graph, and each role is regarded as a node in the directed graph, and the role position tracking error system is determined; Step S3: Design a multi-role distributed position tracking control method based on distributed control theory, including designing virtual control inputs and designing real control inputs; Step S4: Verify the stability and simulation analysis of the control method; including the steps In step S1, each role is regarded as an intelligent entity i, and a dynamic model of a single role is constructed as follows: [Equation 1] where: [Equation 2] is the state variable of the i-th intelligent entity, [Equation 3] is the control input of the i-th intelligent entity, R 2 is a two-dimensional vector space, and n is the dynamic dimension of the intelligent entity i; [Equation 4] are unmodeled dynamics, In step S2, based on the knowledge of graph theory, in the multi-intelligent entity cooperative control, the communication network between the intelligent entities is abstracted into a topology form of information flow, and the network topology structure of the multi-role system is depicted using a directed graph, and each role is regarded as a node in the directed graph, and the role position tracking error system e i1 is determined as follows: [Equation 5] where a ij is the communication topology relationship between nodes, b i is the communication topology relationship between followers and leaders, and x 0 is the leader location information. In step S3, a multi-role distributed position tracking control method is designed based on distributed control theory, and the virtual control input α i is designed as follows: Step S311: Based on the position tracking error system of step S2, a differential calculation of e i1 is performed as follows: [Equation 6] where e i2 is the error signal of x i+1 , and e i2 =x i+1 -α i , Step S312: The Lyapunov function V i1 is selected as follows: [Equation 7] By differential calculation, we obtain the following: [Equation 8] S313: Based on the above steps, design the virtual control input as follows: [Equation 9] where: [Equation 10] is the derivative of the reader position information x 0 , By following the above steps, In step S3, a multi-role distributed position tracking control method is designed based on distributed control theory, and the actual control input u i is designed as follows: Step S321: Observer estimation [0011] is designed as follows: [0012] where p i and l i are adjustable parameters, and if l i > 0, [0013] teeth [0011] is an estimate of The estimated error is: [0014] By differential calculation, we obtain the following: [Equation 15] Step S322: Let e i2 =x i+1 -α i , and obtain the following by differential calculation: [0016] Step S323: Select an appropriate Lyapunov function V i2 as follows: [Equation 17] In the differential calculation, the virtual control input α i is substituted to obtain: [Equation 18] Step S324: The actual control input of the i-th roll is set as follows: [Equation 19] where c i2 is a tunable parameter, In step S4, the stability of the control method is verified by examining unmodeled dynamics. [Equation 4] , there exist constants γ i including model uncertainties and unknown disturbances, [Equation 20] is satisfied, A multi-roll distributed cooperative position tracking control method for roll bending, characterized in that for a multi-roll position control system with a lower triangular structure, an interference observer and a distributed position tracking controller are combined, and the bounded stability of the roll position tracking error is guaranteed by selecting appropriate parameters.

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