Control Method and System for Flexible Manipulator

Abstract

The present invention provides a control method and system for a flexible robotic arm. The method includes: constructing a control system for the target flexible robotic arm and establishing a basic control law for the target flexible robotic arm; determining and adjusting the system input data and system output data of the control system based on the basic control law; processing the adjusted system input data and system output data to obtain a control quantity corresponding to the target flexible robotic arm; and controlling the target flexible robotic arm based on the control quantity. By using the above invention, the control accuracy of the system can be improved, and the control system with control parameters having a large hysteresis has a faster response speed.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical control, and more specifically, to a control method and system for a flexible robotic arm. Background Art

[0002] At present, the series structure of a flexible robotic arm will inevitably cause the problem of end vibration, which will severely limit the working range and operating speed of the robotic arm, and thus have a greater impact on the working accuracy and working efficiency. To effectively improve production efficiency and stability, controlling the robotic arm joints in response to the end vibration of the robotic arm is a practical means.

[0003] Although the traditional PID control method is simple to operate and has high stability, based on traditional feedback control, it is difficult to handle the hysteresis and large disturbances that often occur in the actual working conditions of a flexible robotic arm, and it is unable to track the set value while suppressing interference. Therefore, the control accuracy and response rate are poor. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide a control method and system for a flexible robotic arm to solve the problems of large hysteresis and disturbances existing in the existing robotic arm control methods, and slow response speed for complex working conditions.

[0005] The control method for a flexible robotic arm provided by the present invention includes: constructing a control system for the target flexible robotic arm, and establishing a basic control law for the target flexible robotic arm; based on the basic control law, determining and adjusting the system input data and system output data of the control system; processing the adjusted system input data and system output data to obtain a control quantity corresponding to the target flexible robotic arm; and controlling the target flexible robotic arm based on the control quantity.

[0006] In addition, an optional technical solution is that the control system includes an inner control loop and an outer control loop. The process of constructing a control system for the target flexible robotic arm and establishing a basic control law for the target flexible robotic arm includes: constructing the inner control loop based on a two-degree-of-freedom fixed-value feedforward speed controller, and constructing the outer control loop using a proportional-link position control loop; establishing the basic control law based on the inner control loop and the outer control loop.

[0007] In addition, an optional technical solution is that the expression of the basic control law is:

[0008]

[0009] ω mri =K ppi (θ mri -θmi )

[0010] wherein, u i is the control quantity in the control system; K fvi is the feedforward gain in the speed controller; K ivi is the integral gain in the speed controller; K pvi is the proportional gain in the speed controller; K ppi is the proportional gain in the position control; θ mri is the motor reference angular displacement; θ mi is the motor output angular displacement; is the motor output angular velocity; ω mri is the motor reference angular velocity, and t is time.

[0011] In addition, an optional technical solution is that the process of determining and adjusting the system input data and system output data of the control system based on the basic control law includes: obtaining the system deviation and deviation change rate of the control system; using the system deviation and deviation change rate as two components of the system input data; and adjusting the two components to adjust the system output data.

[0012] In addition, an optional technical solution is that the process of performing data processing on the adjusted system input data and system output data to obtain the control quantity corresponding to the target flexible manipulator includes: constructing the language threshold and membership function of the system input data and system output data; and constructing a fuzzy rule database; based on the fuzzy rule database, language threshold and membership function, performing fuzzy thrust on the control quantity to obtain a set of fuzzy inference results; and determining the control quantity based on the set of fuzzy inference results.

[0013] In addition, an optional technical solution is that constructing the language threshold and membership function of the system input data and system output data includes: defining the variable range and universe of discourse of the system input data and system output data, and each point in the universe of discourse has at least one membership function area; determining the language threshold based on the variable range and universe of discourse; and determining the membership function and type of the membership function of the input variable based on the fuzzy information processing method.

[0014] In addition, an optional technical solution is that constructing the fuzzy rule database includes: constructing the fuzzy rule database by using the processing method of fuzzy variables according to the characteristics of the system input data, combining historical operation experience data and the operation principle of the controlled object.

[0015] In addition, an alternative technical solution is to determine the control quantity based on the fuzzy inference result set, including: based on the fuzzy rule database, using the maximum membership degree method to perform fuzzy inference on the control quantity and obtain the fuzzy inference result set; solving the average value of the element with the largest membership degree in the fuzzy inference result set to determine the control quantity.

[0016] In addition, an alternative technical solution is to set a partial overlap with an overlap rate of 0.2 - 0.6 between each membership function.

[0017] According to another aspect of the present invention, there is provided a control system for a flexible robotic arm, including: a control parameter construction unit for constructing a control system for the target flexible robotic arm and establishing a basic control law for the target flexible robotic arm; an input / output data determination unit for determining and adjusting the system input data and system output data of the control system based on the basic control law; a control quantity acquisition unit for performing data processing on the adjusted system input data and system output data to obtain a control quantity corresponding to the target flexible robotic arm; and a control unit for controlling the target flexible robotic arm based on the control quantity.

[0018] Using the above control method and system for the flexible robotic arm, constructing a control system for the target flexible robotic arm and establishing a basic control law for the target flexible robotic arm, then based on the basic control law, determining and adjusting the system input data and system output data of the control system; performing data processing on the adjusted system input data and system output data to obtain a control quantity corresponding to the target flexible robotic arm, and finally controlling the target flexible robotic arm based on the control quantity, which can avoid using complex mathematical models, realize online correction of data parameters, provide a theoretical basis for vibration suppression control of the flexible robotic arm, achieve rapid response of the robotic arm, adapt to complex working conditions, and improve working precision and efficiency.

[0019] To achieve the above and related purposes, one or more aspects of the present invention include the features described in detail hereinafter. The following description and the accompanying drawings illustrate certain exemplary aspects of the present invention in detail. However, these aspects merely indicate some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] By referring to the following description in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more apparent and easier to understand. In the drawings:

[0021] Figure 1 It is a flowchart of a control method for a flexible robotic arm according to an embodiment of the present invention;

[0022] Figure 2 Schematic diagram of fuzzy control according to an embodiment of the present invention;

[0023] Figure 3 Schematic control diagram of a flexible robotic arm according to an embodiment of the present invention.

[0024] In all the drawings, the same reference numerals indicate similar or corresponding features or functions. Detailed implementation manners

[0025] In the following description, for the purpose of illustration, in order to provide a comprehensive understanding of one or more embodiments, many specific details are set forth. However, it is obvious that these embodiments can also be implemented without these specific details. In other instances, well-known structures and devices are shown in block diagram form for the purpose of facilitating the description of one or more embodiments.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0027] To describe in detail the control method and system of the above flexible robotic arm, the specific embodiments of the present invention will be described in detail below with reference to the drawings.

[0028] Figure 1 Shows a schematic flow of the control method of a flexible robotic arm according to an embodiment of the present invention; Figure 2 and Figure 3 Respectively show the schematic principles of fuzzy control and overall control in the embodiments of the present invention.

[0029] As Figures 1 to 3 Collectively shown, the control method of the flexible robotic arm in the embodiments of the present invention mainly includes the following steps:

[0030] S110: Construct a control system for the target flexible robotic arm and establish a basic control law for the target flexible robotic arm;

[0031] S120: Based on the basic control law, determine and adjust the system input data and system output data of the control system;

[0032] S130: Process the adjusted system input data and system output data to obtain the control quantity corresponding to the target flexible robotic arm;

[0033] S140: Control the target flexible robotic arm based on the control quantity.

[0034] Among them, the control system further includes an inner control loop and an outer control loop. The process of constructing the control system for the target flexible robotic arm and establishing the basic control law for the target flexible robotic arm includes: constructing the inner control loop based on a two-degree-of-freedom fixed-value feedforward speed controller, and constructing the outer control loop using a proportional-link position control loop; furthermore, establish the basic control law based on the inner control loop and the outer control loop.

[0035] As a specific example, the expression of the basic control law is:

[0036]

[0037] ω mri =K ppi (θ mri -θ mi )

[0038] Among them, u i is the control quantity in the control system; K fvi is the feedforward gain in the speed controller; K ivi is the integral gain in the speed controller; K pvi is the proportional gain in the speed controller; K ppi is the proportional gain in the position control; θ mri is the motor reference angular displacement; θ mi is the motor output angular displacement; is the motor output angular velocity; ω mri is the motor reference angular velocity, and t is time.

[0039] Regarding step S120, the process of determining and adjusting the system input data and system output data of the control system based on the basic control law includes: obtaining the system deviation and the deviation change rate of the control system; using the system deviation and the deviation change rate as two components of the system input data; adjusting the two components to adjust the system output data.

[0040] Among them, the process of processing the adjusted system input data and system output data to obtain the control quantity corresponding to the target flexible manipulator includes: constructing the language threshold and membership function of the system input data and system output data; and constructing a fuzzy rule database; based on the fuzzy rule database, language threshold and membership function, performing fuzzy inference on the control quantity to obtain a set of fuzzy inference results; determining the control quantity based on the set of fuzzy inference results.

[0041] In a specific embodiment of the present invention, the process of constructing the language threshold and membership function of the system input data and system output data may include: defining the variable range and domain of the system input data and system output data, and each point in the domain has at least one membership function area; determining the language threshold based on the variable range and domain; determining the membership function and type of the input variable based on the fuzzy information processing method. In this process, in order to ensure the accuracy of processing, a partially overlapping part with an overlap rate of 0.2-0.6 is set between the membership functions.

[0042] In addition, in the process of constructing the fuzzy rule database, the fuzzy rule database can be constructed by using the processing method of fuzzy variables according to the characteristics of the system input data, combined with historical operation experience data or on-site expert operation experience and the operation principle of the controlled object.

[0043] Among them, determining the control quantity based on the set of fuzzy inference results includes: based on the fuzzy rule database, performing fuzzy inference on the control quantity by using the maximum membership degree method and obtaining a set of fuzzy inference results; solving the average value of the element with the largest membership degree in the set of fuzzy inference results to determine the control quantity.

[0044] As a specific example, based on the established fuzzy rule database, the maximum membership degree method is used to calculate the output data, and the data output set u of the control quantity is obtained i :

[0045] u i = MAX u v (v)

[0046] In the formula, v belongs to the system output data V; when there are multiple data in the data output set u i that simultaneously satisfy the maximum membership degree method, the multiple output data can be averaged:

[0047]

[0048] In the formula, u is the output data; M is the number of data that meet the maximum membership degree method; thus, according to the inference result, the fuzzy inference result is converted into a clear control quantity, and further combined with Figure 3For the control method of the flexible robotic arm, it is known that the present invention adds the motor angular velocity ω mri to the system control quantity u through feedforward i . It is a control method that adjusts the integral coefficient K and the proportional coefficient K in real time according to the input error and its change rate of the input data ivi , so as to correct the control parameters. Finally, the robotic arm is controlled by the motor to perform motion, realizing precise control. pvi

[0049] Corresponding to the above control method of the flexible robotic arm, the present invention also provides a control system for the flexible robotic arm, including: a control parameter construction unit for constructing a control system for the target flexible robotic arm and establishing a basic control law for the target flexible robotic arm; an input / output data determination unit for determining and adjusting the system input data and system output data of the control system based on the basic control law; a control quantity acquisition unit for processing the adjusted system input data and system output data to obtain a control quantity corresponding to the target flexible robotic arm; and a control unit for controlling the target flexible robotic arm based on the control quantity.

[0050] It should be noted that the embodiments of the above control system of the flexible robotic arm can refer to the description in the embodiments of the control method of the flexible robotic arm, and will not be elaborated here one by one.

[0051] According to the above control method and system of the flexible robotic arm, construct a control system for the target flexible robotic arm and establish a basic control law for the target flexible robotic arm. Then, based on the basic control law, determine and adjust the system input data and system output data of the control system; process the adjusted system input data and system output data to obtain a control quantity corresponding to the target flexible robotic arm. Finally, control the target flexible robotic arm based on the control quantity, which can simply and accurately establish a control system for the flexible robotic arm to reduce the influence of the vibration at the end of the flexible robotic arm, providing a theoretical basis for vibration suppression of the flexible robotic arm and improving the positioning accuracy; at the same time, it can avoid using complex mathematical models, realize online correction of data parameters, and improve the control accuracy and efficiency of the flexible robotic arm.

[0052] As described above, the control method and system of the flexible robotic arm according to the present invention are described by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various improvements can be made to the above control method and system of the flexible robotic arm proposed by the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the appended claims.

Claims

1. A control method for a flexible robotic arm, characterized in that, Including: Construct a control system for the target flexible manipulator and establish the basic control law for the target flexible manipulator. Based on the basic control law, determine and adjust the system input data and system output data of the control system. Process the adjusted system input data and system output data to obtain the control quantity corresponding to the target flexible manipulator. Control the target flexible manipulator based on the control quantity; the control system includes an inner control loop and an outer control loop. The process of constructing the control system for the target flexible manipulator and establishing the basic control law for the target flexible manipulator includes: Construct the inner control loop based on a two-degree-of-freedom fixed-value feedforward speed controller, and construct the outer control loop using a proportional-link position control loop. Based on the inner control loop and the outer control loop, establish the basic control law. The expression of the basic control law is: ω mri = K ppi (θ mri - θ mi ) where, u i is the control variable in the control system; K fvi is the feedforward gain in the speed controller; K ivi is the integral gain in the speed controller; K pvi is the proportional gain in the speed controller; K ppi is the proportional gain in the position control; θ mri is the motor reference angular displacement; θ mi is the motor output angular displacement; is the motor output angular velocity; ω mri is the motor reference angular velocity, and t is time.

2. The control method of the flexible robotic arm according to claim 1, characterized in that, Based on the basic control law, the process of determining and adjusting the system input data and system output data of the control system includes: Obtain the system deviation and deviation change rate of the control system. Use the system deviation and the deviation change rate as two components of the system input data. Adjust the system output data by adjusting the two components.

3. The control method of the flexible robotic arm according to claim 1, characterized in that, The process of processing the adjusted system input data and system output data to obtain the control quantity corresponding to the target flexible manipulator includes: Construct the linguistic thresholds and membership functions of the system input data and the system output data; and construct a fuzzy rule database. Based on the fuzzy rule database, the linguistic thresholds, and the membership functions, perform fuzzy inference on the control quantity to obtain a set of fuzzy inference results. Determine the control quantity based on the set of fuzzy inference results.

4. The control method of the flexible robotic arm according to claim 3, characterized in that, The construction of the linguistic thresholds and membership functions of the system input data and the system output data includes: Define the variable ranges and universes of discourse of the system input data and the system output data, and each point in the universe of discourse has at least one membership function area. Determine the linguistic thresholds based on the variable ranges and the universes of discourse. Based on the fuzzy information processing method, determine the membership functions of the system input data and the types of the membership functions.

5. The control method of the flexible robotic arm according to claim 3, characterized in that, The construction of the fuzzy rule database includes: According to the characteristics of the system input data, combined with historical operation experience data and the operation principle of the controlled object, construct the fuzzy rule database using the processing method of fuzzy variables.

6. The control method of the flexible robotic arm according to claim 3, characterized in that, Based on the set of fuzzy inference results, determining the control quantity includes: Based on the fuzzy rule database, perform fuzzy inference on the control quantity using the maximum membership degree method and obtain the set of fuzzy inference results. Solve the average value of the element with the largest membership degree in the set of fuzzy inference results to determine the control quantity.

7. The control method of the flexible manipulator according to claim 3, characterized in that A partial overlap with an overlap rate of 0.2 - 0.6 is set between each of the membership functions.

8. A control system for a flexible robotic arm, characterized in that, Including: A control parameter construction unit, which is used to construct a control system for a target flexible manipulator and establish a basic control law for the target flexible manipulator; An input / output data determination unit, which is used to determine and adjust the system input data and system output data of the control system based on the basic control law; A control quantity acquisition unit, which is used to process the adjusted system input data and system output data to obtain a control quantity corresponding to the target flexible manipulator; A control unit, which is used to control the target flexible manipulator based on the control quantity; The control system includes an inner control loop and an outer control loop. Constructing the control system for the target flexible manipulator and establishing the basic control law for the target flexible manipulator includes: Constructing the inner control loop based on a two-degree-of-freedom fixed-value feedforward speed controller, and constructing the outer control loop using a proportional-link position control loop; Establishing the basic control law based on the inner control loop and the outer control loop; The expression of the basic control law is: ω mri = K ppi (θ mri - θ mi ) Among them, u i is the control quantity in the control system; K fvi is the feedforward gain in the speed controller; K ivi is the integral gain in the speed controller; K pvi is the proportional gain in the speed controller; K ppi is the proportional gain in the position control; θ mri is the motor reference angular displacement; θ mi is the motor output angular displacement; is the motor output angular velocity; ω mri is the motor reference angular velocity, and t is time.

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