A design method of intelligent PID control for snake-like robot based on hyperlocal model

Abstract

The present invention discloses a design method for intelligent PID control of a snake-like robot based on a hyperlocal model, including: establishing a dynamic model of a multi-degree-of-freedom snake-like robot; establishing a hyperlocal model of the multi-degree-of-freedom snake-like robot according to the definition of the hyperlocal model, optimizing the model, and solving the problem of inaccurate mathematical model caused by disturbance and uncertain parameters; designing a time delay estimator to estimate the uncertain terms and external disturbances of the multi-degree-of-freedom snake-like robot; and designing an intelligent PID control method based on the hyperlocal model of the multi-degree-of-freedom snake-like robot with time delay to achieve rapid convergence within a limited time. The present invention applies the hyperlocal model to the dynamic model of the multi-degree-of-freedom snake-like robot, overcomes the problem of inaccurate modeling or inaccurate parameters of the dynamic model of the multi-degree-of-freedom snake-like robot; and realizes high-precision tracking control of the multi-degree-of-freedom snake-like robot with simple key parameters.

Description

Technical Field

[0001] The invention relates to the technical field of electrical automation, and in particular to a snake-like robot intelligent PID control design method based on a super-local model. Background Art

[0002] Bionic snake-like robots have a wide range of applications, involving various scenarios on land, sea and air. In the field of power grids, drones are not suitable for line inspections in no-fly scenarios, and manual inspections are not suitable in areas with a lot of forests. With its unique body structure and movement mode, snake-like robots can move freely in complex terrain and narrow spaces, which has great advantages for tasks such as power grid inspections, equipment maintenance, and troubleshooting. Nowadays, they are gradually being applied to the inspection of transmission lines and high-voltage cable tunnels.

[0003] However, in actual scenarios, the requirements for inspection and maintenance work are getting higher and higher, and the requirements for the accuracy of motion control of bionic snake-like robots are also further increased. In actual environments, its motion control still faces challenges. The main reasons for the difficulty in motion control are the high control difficulty caused by complex modeling methods, low modeling accuracy, and complex control algorithms. Therefore, it is crucial to break through the dynamic model of bionic snake-like robots and seek simple and efficient control methods for the precise control of bionic snake-like robots. Summary of the invention

[0004] In view of the above existing problems, the present invention proposes an intelligent PID control design method for a snake-like robot based on a super local model.

[0005] Therefore, the present invention provides a snake-like robot intelligent PID control design method based on a super-local model, which can simplify the multi-degree-of-freedom snake-like robot model while providing efficient and accurate control effects.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] Including, establishing the dynamic model of multi-degree-of-freedom snake-like robot;

[0008] According to the definition of hyperlocal model, a hyperlocal model of a multi-DOF snake-like robot is established;

[0009] Design a time delay estimator to estimate the uncertainty and external disturbance of the multi-degree-of-freedom snake robot; design an intelligent PID control method based on the hyperlocal model of the multi-degree-of-freedom snake robot with time delay;

[0010] As a preferred solution of the snake-like robot intelligent PID control design method based on the super-local model described in the present invention, the process of establishing the dynamic model of the multi-degree-of-freedom snake-like robot is as follows:

[0011] ,

[0012] in, , is the joint angle of the snake robot, is the coordinate of the center of mass of the snake robot; is the inertia matrix of the system, ; is the Coriolis and centripetal force matrix, ; are the gravity and friction matrices, , ; is a column vector, , u is the joint input torque.

[0013] The dynamic equations of the multi-degree-of-freedom snake-like robot are split into two parts: the driven part and the non-driven part.

[0014] Rewritten as follows,

[0015] ,

[0016] in, Represents the degrees of freedom that the joint angle can drive; represents the non-actuated degrees of freedom; , , , , , , , are the system parameters of the multi-degree-of-freedom snake-like robot.

[0017] As a preferred solution of the hyperlocal model-based intelligent PID control design method for a snake-like robot described in the present invention, wherein: according to the hyperlocal model definition, a hyperlocal model of a multi-degree-of-freedom snake-like robot is established, including:

[0018] The traditional single-input single-output nonlinear system can be expressed as:

[0019] ,

[0020] in, is the input of the system, is the output of the system, and is a system parameter, but its order is uncertain.

[0021] In order to simplify the nonlinear model without losing system information, the above nonlinear system is rewritten into a hyperlocal model based on the model-free concept as follows:

[0022] ,

[0023] in, It is the system output Derivatives, Usually 1 or 2 is selected; α∈R is a constant without physical meaning and is usually selected based on the experimenter's experience; is the input of the system; F Because the system contains unmodeled dynamics of nonlinear systems, external disturbances and other uncertainties, it needs to be continuously updated based on the input and output information of the system.

[0024] As a preferred solution of the snake-like robot intelligent PID control design method based on super local model described in the present invention, it also includes:

[0025] According to the driving and non-driving equations of the multi-degree-of-freedom snake-like robot, the non-driving solution is:

[0026] ,

[0027] By introducing the non-actuated quantity, the dynamic equation of the multi-degree-of-freedom snake-like robot is further updated as follows:

[0028] .

[0029] As a preferred solution of the snake-like robot intelligent PID control design method based on super local model described in the present invention, it also includes:

[0030] The updated multi-degree-of-freedom snake-like robot meets the characteristics of single-input single-output and satisfies the highest second order. The multi-degree-of-freedom snake-like robot is replaced by a hyperlocal model as follows:

[0031] ,

[0032] in, is the joint angular acceleration vector of the multi-DOF snake-like robot; is a dimensionless constant determined by the experimenter, is the control torque vector, Contains the set of disturbance terms and uncertain terms of the snake robot system.

[0033] The joint angle tracking error is defined as follows:

[0034] ,

[0035] in, is the joint angle tracking error, is the joint angle reference trajectory vector, is the joint angle.

[0036] As a preferred solution of the design method of the snake-like robot intelligent PID control based on the hyperlocal model described in the present invention, a time delay estimator is designed to estimate the uncertainty and external disturbance of the multi-degree-of-freedom snake-like robot as follows:

[0037] The time delay estimator is defined as follows:

[0038] ,

[0039] in, yes An estimate based on a time delay estimator; is the time delay interval. Only when the time delay interval is small enough can the accuracy of the estimation of the disturbance term be guaranteed.

[0040] As a preferred solution of the hyperlocal model-based intelligent PID control design method for a snake-like robot described in the present invention, the hyperlocal model-based intelligent PID control design method for a multi-degree-of-freedom snake-like robot with time delay is designed as follows:

[0041] The control law is designed as:

[0042] ,

[0043] in, ， and Control gains for the proportional, integral, and derivative terms.

[0044] The beneficial effects of the present invention are as follows: the present invention applies a hyperlocal model to the dynamic model of a multi-degree-of-freedom snake-like robot, thereby overcoming the problem of inaccurate modeling or inaccurate parameters of the dynamic model of the multi-degree-of-freedom snake-like robot; a time delay estimator is designed based on the hyperlocal model to track and observe the external disturbance, internal disturbance and uncertain items of the multi-degree-of-freedom snake-like robot in real time for feedback; and an intelligent PID control method is designed at the same time to achieve high-precision tracking control of the multi-degree-of-freedom snake-like robot with simple key parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0046] Figure 1 A schematic diagram of a principle control framework of a design method for intelligent PID control of a snake-like robot based on a super-local model according to an embodiment of the present invention;

[0047] Figure 2 is a comparison of the tracking effects of the snake robot intelligent PID control design method (IPID) based on the hyperlocal model and the traditional PID control method (PID) for the joint angle 1 of the three-degree-of-freedom snake robot at the target trajectory 1 (aim1);

[0048] FIG3 is a comparison diagram of the tracking effect of the three-degree-of-freedom snake robot joint angle 2 under the target trajectory 2 (aim2) using the hyperlocal model-based snake robot intelligent PID control design method (IPID) and the traditional PID control method (PID);

[0049] Figure 4 It is a flowchart of the intelligent PID control design method of the snake-like robot based on the super-local model of the present invention. DETAILED DESCRIPTION

[0050] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0051] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0052] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0053] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0054] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0055] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] Example 1

[0057] Reference Figure 1 , Figure 4 , which is the first embodiment of the present invention, provides a design method for intelligent PID control of a snake-like robot based on a hyperlocal model. The method of the present invention is based on the optimization of the dynamics model of a multi-degree-of-freedom snake-like robot, and combines the definition of the hyperlocal model to establish a hyperlocal model of the dynamics model of a multi-degree-of-freedom snake-like robot; a time delay estimator is designed to track and compensate for disturbances and uncertainties, and an intelligent PID controller is designed to track and control the hyperlocal model of the freedom snake-like robot based on the time delay estimator:

[0058] S1: Establish the dynamic model of the multi-degree-of-freedom snake-like robot. What needs to be explained in this step is: the dynamic model of the multi-degree-of-freedom snake-like robot is as follows:

[0059] ,

[0060] in, , is the joint angle of the snake robot, is the coordinate of the center of mass of the snake robot; is the inertia matrix of the system, ; is the Coriolis and centripetal force matrix, ; and are the gravity and friction matrices, , ; is a column vector, , u is the joint input torque.

[0061] The dynamic equation of the multi-degree-of-freedom snake robot is split into two parts: the driving part and the non-driving part. Rewrite it as follows:

[0062] ,

[0063] in, Represents the degrees of freedom that the joint angle can drive; represents the non-actuated degrees of freedom; , , , , , , , are the system parameters of the multi-degree-of-freedom snake-like robot.

[0064] S2: According to the definition of the hyperlocal model, establish the hyperlocal model of the multi-DOF snake-like robot. The following points need to be explained in this step:

[0065] The traditional single-input single-output nonlinear system can be expressed as:

[0066] ,

[0067] in, is the input of the system, is the output of the system, and is a system parameter, but its order is uncertain.

[0068] In order to simplify the nonlinear model without losing system information, the above nonlinear system is rewritten into a hyperlocal model based on the model-free concept as follows:

[0069] ,

[0070] in, It is the system output Derivatives, Usually 1 or 2 is selected; α∈R is a constant without physical meaning and is usually selected based on the experimenter's experience; is the input of the system; F is the system that contains the unmodeled dynamics of the nonlinear system, external disturbances and other uncertain factors, which needs to be continuously updated according to the input and output information of the system.

[0071] According to the driving and non-driving equations of the multi-degree-of-freedom snake-like robot, the non-driving solution is:

[0072] ,

[0073] By introducing the non-actuated quantity, the dynamic equation of the multi-degree-of-freedom snake-like robot is further updated as follows:

[0074] .

[0075] The updated multi-degree-of-freedom snake-like robot meets the characteristics of single-input single-output and satisfies the highest second order. The multi-degree-of-freedom snake-like robot is replaced by a hyperlocal model as follows:

[0076] ,

[0077] in, is the joint angular acceleration vector of the multi-DOF snake-like robot; is a dimensionless constant determined by the experimenter, is the control torque vector, Contains the set of disturbance terms and uncertain terms of the snake robot system.

[0078] The joint angle tracking error is defined as follows:

[0079] ,

[0080] in, is the joint angle tracking error, is the joint angle reference trajectory vector, is the joint angle.

[0081] S3: Design a time delay estimator to estimate the uncertainty and external disturbance of the multi-degree-of-freedom snake robot. The following points should be noted in this step:

[0082] The time delay estimator is defined as follows:

[0083] ,

[0084] in, yes An estimate based on a time delay estimator; is the time delay interval. Only when the time delay interval is small enough can the accuracy of the estimation of the disturbance term be guaranteed.

[0085] S4: Design of intelligent PID control method based on hyperlocal model of multi-DOF snake-like robot with time delay. The following points should be noted in this step:

[0086] The control law is designed as:

[0087] ,

[0088] in, ， and The control of proportional term, integral term and differential term increases.

[0089] Preferably, it should be noted that, compared with the prior art, this embodiment discloses a design method for intelligent PID control of a snake-like robot based on a hyperlocal model, which aims to replace the actual multi-degree-of-freedom snake-like robot dynamics model with a hyperlocal model to solve the accuracy problem of the mathematical model caused by external disturbances and uncertainties. At the same time, the time delay observer can compensate for uncertainties and external disturbances. The intelligent PID control method can track and control the hyperlocal model of a multi-degree-of-freedom snake-like robot based on time delay to ensure convergence within a limited time.

[0090] Example 2

[0091] Reference Figure 2 ~ Figure 3 , which is another embodiment of the present invention, which is different from the first embodiment in that it provides a test verification of a snake-like robot intelligent PID control design method based on a super-local model, including:

[0092] In order to verify and illustrate the technical effect adopted in this method, in this embodiment, a traditional PID control method is selected to be compared with the method of the present invention, and the test results are compared by scientific demonstration to verify the real effect of this method.

[0093] The physical parameters of the three-degree-of-freedom snake-like robot are: N =4, mass of a single connecting rod of the snake robot The mass of each link is evenly distributed, and the joint length , ground friction , , .

[0094] The vectors and inertia matrix used by the three-degree-of-freedom snake robot system are: , , , , , , , ; , , ; ; .

[0095] The input and output vectors of the snake robot are , , , The initial condition of the snake robot is , , .

[0096] The target trajectory of joint angle 1 is: The target trajectory of joint angle 2 is: .

[0097] The parameters of the intelligent PID controller of the present invention are: , , , , .

[0098] The comparison controller is a traditional PID controller: The controller parameters are , , .

[0099] Test environment: Reference Figure 1 In the SIMULINK environment of MATLAB 2019a, a snake robot controlled object model is built according to the existing snake robot physical quantity parameters and mathematical models. The intelligent PID control method based on the super-local model and the traditional PID control method are used to track and control the driven joint 1 and the driven joint 2 under different target trajectories and obtain the test result data. Both methods will start the automated test equipment and use the MATLB software to program the simulation test of the comparison method. The simulation data is obtained according to the test results. Each method tests 4 groups of data, and each group of data is sampled for 15 s. The target trajectory of each group of data input and the tracking trajectory of the output are calculated and compared to verify the feasibility of the proposed algorithm.

[0100] Reference Figure 2 The tracking effect of the driving joint angle 1 of the present invention on the target trajectory 1 (aim1) is compared between the intelligent PID control method (IPID) based on the super local model and the traditional PID control method (PID). Figure 3The present invention drives joint angle 2 to track the target trajectory 2 (aim2) under the intelligent PID control method (IPID) based on the hyperlocal model and the traditional PID control method (PID) to compare the tracking effect. As can be seen from the figure, the intelligent PID control method (IPID) based on the hyperlocal model and the traditional PID control method (PID) can track the target trajectory 1 (aim1) and the target trajectory 2 (aim2) as a whole. However, it is obviously found that the traditional PID control method (PID) is worse than the intelligent PID control method (IPID) based on the hyperlocal model in terms of rapidity and control accuracy, and the tracking effect of the traditional PID control method (PID) for the target trajectory 1 (aim1) is worse than that for the target trajectory 2 (aim2). The intelligent PID control method (IPID) based on the hyperlocal model can track the two target trajectories with high precision, and the hyperlocal model can track and compensate for its own disturbance terms and uncertain terms by using the time delay estimator, thereby further eliminating errors, achieving rapid convergence and achieving precise control.

[0101] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A design method for intelligent PID control of a snake-like robot based on a hyperlocal model, characterized by: include, S1. Establish the dynamic model of the multi-degree-of-freedom snake-like robot; S2. According to the definition of the hyperlocal model, a hyperlocal model of the multi-DOF snake-like robot is established; S3. Design a time delay estimator to estimate the uncertainties and external disturbances of a multi-DOF snake robot; S4. Based on the hyperlocal model of multi-DOF snake-like robot with time delay, an intelligent PID control method is designed for tracking control; The dynamic model of the multi-degree-of-freedom snake-like robot is as follows: in, φ is the joint angle of the snake robot, and p is the coordinate of the center of mass of the snake robot; is the inertia matrix of the system, is the Coriolis and centripetal force matrix, and are the gravity and friction matrices, is a column vector, u is the joint input torque; The dynamic equation of the multi-degree-of-freedom snake robot is split into two parts: the driving quantity and the non-driving quantity, and rewritten as follows: in, Represents the degrees of freedom that the joint angle can drive; represents the non-actuated degrees of freedom; are the system parameters of the multi-DOF snake-like robot; The hyperlocal model of the multi-DOF snake-like robot is established as follows: The updated multi-degree-of-freedom snake-like robot meets the characteristics of single-input single-output and satisfies the highest second order. The multi-degree-of-freedom snake-like robot is replaced by a hyperlocal model as follows: in, is the joint angular acceleration vector of the multi-DOF snake-like robot; a is a dimensionless constant determined by the experimenter, u is the control torque vector, Contains the set of disturbance terms and uncertain terms of the snake robot system; The joint angle tracking error is defined as follows: e=φ ref -φ (8), Where e is the joint angle tracking error, φ ref is the joint angle reference trajectory vector, φ is the joint angle; The time delay estimator design is established as follows, The time delay estimator is defined as follows: in, is the estimated value of F(t) based on the time delay estimator; Δt is the time delay interval. Only when the time delay interval is small enough can the accuracy of the disturbance term be guaranteed; The intelligent PID control method based on time delay estimator is designed as follows: The control law is designed as: Among them, k p , k i and k d Control gains for the proportional, integral, and derivative terms.

2. The method for designing a snake-like robot intelligent PID control based on a super-local model according to claim 1 is characterized in that: The hyperlocal model is defined as follows, The traditional single-input single-output nonlinear system can be expressed as: Among them, u(t) is the input of the system, y(t) is the output of the system, and a n With b m are system parameters, where n = 1, 2, 3, ..., m = 1, 2, 3 ..., but their order is uncertain; In order to simplify the nonlinear model without losing system information, the above nonlinear system is rewritten into a hyperlocal model based on the model-free concept as follows: y (v) =au(t)+F (4), Among them, y (v) is the v-th order derivative of the system output, v is selected as 1 or 2; a∈R is a constant without physical meaning, which is selected according to the experience of the experimenter; u(t) is the input of the system; F is the system, which contains the unmodeled dynamics of the nonlinear system, external disturbances and other uncertain factors, and needs to be continuously updated according to the input and output information of the system.

3. The method for designing a snake-like robot intelligent PID control based on a super-local model according to claim 1 is characterized in that: The driving and non-driving equations of the multi-degree-of-freedom snake-like robot are further rewritten as a single-input single-output dynamics model. According to the driving and non-driving equations of the multi-degree-of-freedom snake-like robot, the non-driving solution is: By introducing the non-actuated quantity, the dynamic equation of the multi-degree-of-freedom snake-like robot is further updated as follows:

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