A method, device, and storage medium for path tracking control of a dual-steering wheel AGV.

Abstract

This invention discloses a path tracking control method, device, and storage medium for a dual-steering-wheel AGV. The method includes: constructing a kinematic model in a servo coordinate system; updating the kinematic model by introducing new control variables; and solving the updated kinematic model to obtain control variables unaffected by the rotation angles of the two steering wheels. By using the method of this invention to obtain the control variables of a dual-steering-wheel AGV, the singular shape of the AGV can be handled without special processing, allowing the AGV to move along the path at any attitude angle.

Description

Technical Field

[0001] This invention relates to the field of AGV control technology, and in particular to a path tracking control method, device, and storage medium for a dual-steering wheel AGV. Background Technology

[0002] Currently, omnidirectional motion capability has gradually become a basic requirement for industrial AGVs. The dual-steering-wheel AGV is a basic type of omnidirectional AGV, characterized by its simple structure and convenient maintenance. However, the control of dual-steering-wheel AGVs is relatively complex. Its main problem is the existence of a singular shape: when both steering wheels are perpendicular to the line connecting them, the AGV becomes a two-wheel differential drive, degenerating from three degrees of freedom to two degrees of freedom, and losing its omnidirectional motion characteristics.

[0003] In existing technologies, the control methods for dual-steering-wheel AGVs do not specifically consider their controllability in unusual configurations, thus failing to achieve complete AGV controllability. Alternatively, they may avoid unusual configurations by limiting the steering wheel angle to prevent the steering wheel from being perpendicular to the connecting line, or by controlling unusual configurations independently. This results in control methods lacking versatility and unable to adapt to all states of the dual-steering-wheel AGV. Furthermore, most current dual-steering-wheel AGV control methods aim at tangential tracking of the AGV body along the path, rather than tracking at arbitrary attitude angles. Summary of the Invention

[0004] The purpose of this invention is to provide a dual-steering wheel AGV path tracking control method, device, and storage medium to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions.

[0005] The solution to the technical problem of this invention is to provide a dual-steering wheel AGV path tracking control method and device, and a storage medium.

[0006] According to an embodiment of a first aspect of the present invention, a path tracking control method for a dual-steering wheel AGV is provided, comprising the following steps:

[0007] Obtain the currently tracked path and AGV reference point; establish a vehicle coordinate system based on the AGV reference point; obtain orthogonal projection points on the path based on the path and AGV reference point; and establish a follow-up coordinate system based on the orthogonal projection points.

[0008] Based on the aforementioned follower coordinate system, a kinematic model is constructed in the follower coordinate system;

[0009] Based on the speed and angle of the two steering wheels, the control variables are determined, the speed of one of the steering wheels is set as the target speed, a new control variable is introduced, and the kinematic model is updated.

[0010] Based on the path, the updated kinematic model, and the motion mode set by the dual-steering wheel AGV, the new control variables for the next moment are obtained;

[0011] The control variables are calculated based on the new control variables, target speed, and the rotation angles of the two steering wheels at the next moment.

[0012] Furthermore, the process of establishing the following coordinate system specifically includes:

[0013] Set the rotation center points of the two steering wheels as points A and B respectively. Select point A as the AGV reference point. Based on the AGV reference point, establish the vehicle coordinate system xAy, where the x-axis coincides with the line connecting the two steering wheels and points in the forward direction, and the y-axis points to the left.

[0014] Let the orthogonal projection point of the AGV reference point on the path be point P, and establish a follower coordinate system with the orthogonal projection point as the origin. in, The axis points tangentially to point P. The axis points to the left.

[0015] Furthermore, the construction of the kinematic model specifically includes:

[0016] Get the global coordinates [X, Y] of point A. T Based on the global coordinates [X, Y] T The global velocity of point A is:

[0017]

[0018] The angular velocity of the vehicle body is:

[0019] Obtain the distance d from point P to point A, the curvature k at point P, and let the path length s traversed by point P on the path be , then obtain the rotational angular velocity of the following coordinate system. And according to the rotational angular velocity The transformation yields the kinematic model in the following coordinate system:

[0020]

[0021] Among them, v A Let be the speed of the steering wheel at point A, α and β be the rotation angles of the steering wheel at point A and point B, respectively, and L be the distance between the two steering wheels.

[0022] Furthermore, the process of determining the control variables and the process of updating the kinematic model specifically include:

[0023] If the two steering wheels have the same velocity along the line connecting them, then v Acosα=v B cosβ, v A Let v be the target velocity, where v B Let B be the speed of the steering wheel;

[0024] Introducing a new control variable σ, the kinematic model is updated as follows:

[0025]

[0026] Where σ = 1 / R A |σ|<1 / L, R A Let be the instantaneous rotation radius of the steering wheel at point A.

[0027] Furthermore, the process of obtaining the new control variable at the next moment specifically includes:

[0028] Let θ e =θ m -θ c -θ d To make the dual-steering wheel AGV reach the target attitude angle θ d To perform tracking, where θ m Let θ be the vehicle's heading angle. c Let P be the tangent angle;

[0029] In the updated kinematic model Taking the derivative, we get And Linearization brings d to zero, based on the derivative obtained. and linearization Get control quantity right Numerical integration is performed to obtain the control quantity α at the next time step;

[0030] For the θ e Taking the second derivative, we get Determine the target attitude angle θ based on the set motion mode. d ,Will Linearize and convert θ e Converging to zero, according to the derivative... and linearization Get control quantity right Numerical integration is performed to obtain the control quantity σ at the next time step.

[0031] Furthermore, the process of obtaining the control quantity α at the next moment specifically includes:

[0032] Regarding the Differentiation yields

[0033]

[0034] Using PD feedback control Linearization, let: d converges to zero, where λ pd , λ dd All are coefficients greater than zero;

[0035] According to the derivative and linearization get The control quantity is:

[0036]

[0037] right Numerical integration is performed to obtain the control quantity α at the next time step.

[0038] Furthermore, the process of obtaining the control quantity σ at the next moment specifically includes:

[0039] For θ e Taking the second derivative, we get Where k′ is the rate of change of curvature of the path;

[0040] When the set motion mode is a fixed angle γ relative to the tangential direction of the path, then θ d =γ, therefore

[0041] When the azimuth angle γ of the AGV motion mode remains constant regardless of the path direction, then θ d +θ c =γ, therefore

[0042] Using PD feedback control Linearization, let θ e It converges to zero, where λ pθ , λ dθ All are coefficients greater than zero;

[0043] According to the derivative and linearization get The control quantity is:

[0044]

[0045] right Numerical integration is performed to obtain the control quantity σ at the next time step.

[0046] Furthermore, the process of obtaining the control variables specifically includes:

[0047] Introducing intermediate control variable β d And satisfy:

[0048]

[0049] Then there is And by differentiating both sides, we get

[0050] Design linear proportional feedback λ β For coefficients greater than zero, based on the aforementioned linear proportional feedback and get Control Law:

[0051]

[0052] right Perform numerical integration to obtain the control variable β at the next time step;

[0053] v A cosα=v B In cosβ, replace β with β d And according to cosβ d The control variable v is obtained. B ,

[0054] According to a second aspect of the present invention, an electronic device is provided, comprising:

[0055] A memory for storing a program; a processor for executing the program stored in the memory, wherein when the processor executes the program stored in the memory, the processor is configured to execute a dual-steering wheel AGV path tracking control method as described in any one of the first aspects.

[0056] According to a third aspect of the present invention, a storage medium is provided, comprising: storing computer-executable instructions for performing a dual-steering wheel AGV path tracking control method as described in any one of the first aspects.

[0057] The beneficial effects of this invention are: by constructing a kinematic model in a servo coordinate system, updating the kinematic model by introducing new control variables, and solving the updated kinematic model, control variables unaffected by the rotation angles of the two steering wheels are obtained. Using the method in this invention, the control variables of a dual-steering-wheel AGV can be obtained, thus eliminating the need for special handling of the AGV's singular shape and allowing the AGV to move along a path at any attitude angle. Attached Figure Description

[0058] Figure 1 This is a schematic flowchart of a path tracking control method for a dual-steering wheel AGV provided by the present invention;

[0059] Figure 2 This is a schematic diagram in global coordinates of a dual-steering wheel AGV path tracking control method provided by the present invention;

[0060] Figure 3 This is an example diagram illustrating the motion mode of a dual-steering wheel AGV path tracking control method provided by the present invention. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and should not be construed as limiting the scope of the invention.

[0062] It should be noted that although functional modules are divided in the system diagram, in some cases, the steps shown or described may be executed in a different order than the module division or flowchart shown in the system. The terms "first," "second," etc., in the specification, claims, and the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0063] In the description of this invention, it should be noted that, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0064] According to an embodiment of the first aspect of the present invention, referring to Figure 1 and Figure 2 In some embodiments of the present invention, a path tracking control method for a dual-steering wheel AGV includes the following steps:

[0065] S100: Obtain the currently tracked path and AGV reference point. Based on the AGV reference point, establish the vehicle coordinate system. Based on the path and AGV reference point, obtain the orthogonal projection points on the path. Based on the orthogonal projection points, establish the follow-up coordinate system.

[0066] In this embodiment, under the global coordinate system XOY, the path C that the dual-steering wheel AGV is tracking is obtained, and a reference point for the tracking control of the dual-steering wheel AGV, i.e., the AGV reference point, is selected. Using the AGV reference point as the origin, a local coordinate system for the vehicle body, i.e., the vehicle body coordinate system xAy, is constructed. The AGV reference point is orthogonally projected onto path C to obtain an orthogonal projection point. Using the orthogonal projection point as the origin, a follow-up coordinate system is constructed.

[0067] S200, based on the following coordinate system, constructs a kinematic model in the following coordinate system.

[0068] In this embodiment, a kinematic model is constructed in the following coordinate system obtained through S100. Compared with the existing Cartesian coordinate system, the following coordinate system can more conveniently and intuitively describe the position of the vehicle relative to the path C, especially the curved path.

[0069] When constructing a kinematic model using a servo coordinate system, path curvature information is included, while that is not present in a Cartesian coordinate system. Therefore, this control method can track curves more naturally.

[0070] S300 determines the control variables based on the speed and angle of the two steering wheels, sets the speed of one of the steering wheels as the target speed, introduces new control variables, and updates the kinematic model.

[0071] In this embodiment, the control variables of the dual-steering-wheel AGV are determined based on the speed and angle of one steering wheel and the speed and angle of the other steering wheel, both located on the same vehicle body. In practical applications, the target speed is usually the speed of one of the steering wheels.

[0072] New control variables are introduced to replace the control variables in the original kinematic model, thus updating the kinematic model and obtaining the updated kinematic model.

[0073] S400 obtains new control variables for the next moment based on the path, the updated kinematic model, and the motion mode set by the dual-steering wheel AGV.

[0074] In this embodiment, the motion mode set by the dual-steering wheel AGV is obtained, and combined with the path C information, the updated kinematic model obtained in S300 is used to calculate and obtain the new control variables for the next moment.

[0075] S500 calculates the control variables based on the new control variables, target speed, and the rotation angle of the two steering wheels at the next moment.

[0076] In this embodiment, the control variables of the dual-steering wheel AGV are obtained by using the new control variables obtained in S400 at the next moment, and by calculating the target speed and the rotation angle of the two steering wheels.

[0077] A kinematic model is constructed in a servo coordinate system. By introducing new control variables, the kinematic model is updated, and the updated kinematic model is solved to obtain control variables that are unaffected by the rotation angles of the two steering wheels. Using the method described in this invention, the control variables of a dual-steering-wheel AGV can be obtained, thus eliminating the need for special handling of the AGV's singular shape and enabling the AGV to move along a path at arbitrary attitude angles.

[0078] Reference Figure 2 In some embodiments of the present invention, the process of establishing the follower coordinate system in S100 includes the following specific steps:

[0079] S110, the rotation center points of the two steering wheels are points A and B respectively. Point A is selected as the reference point for AGV tracking control. The vehicle coordinate system xAy is established with point A as the origin.

[0080] In this embodiment, the rotation center point of one steering wheel is designated as point A, and the rotation center point of the other steering wheel is designated as point B. The AGV reference point is point A. A local coordinate system xAy is established with point A as the origin. The x-axis coincides with the line connecting the two steering wheels and points in the forward direction. The y-axis is perpendicular to the x-axis and points to the left.

[0081] Among them, v A Let v be the velocity at point A. B Let θ be the velocity of the steering wheel corresponding to point B, α be the rotation angle of the steering wheel corresponding to point A, β be the rotation angle of the steering wheel corresponding to point B, and let L be the distance between the two steering wheels. m Let θ be the vehicle's heading angle. d For the target attitude angle, I cr As the instantaneous center of rotation, R A Let be the instantaneous rotation radius of the steering wheel at point A.

[0082] S120, point P is the orthogonal projection of point A onto the path. A moving coordinate system is established with point P as the origin. in, The axis points tangentially to point P. The axis points to the left.

[0083] In this embodiment, point P is the AGV reference point, i.e., point A, and its orthogonal projection onto path C. θ c Let P be the tangential angle, and establish a moving coordinate system with P as the origin. in, The axis points tangentially to point P. Axis perpendicular The axis points to the left.

[0084] Reference Figure 2In some embodiments of the present invention, in S200, the construction of the kinematic model includes the following specific steps:

[0085] S210, obtain the global coordinates [X, Y] of point A. T Based on global coordinates [X, Y] T The global velocity of point A is:

[0086]

[0087] The angular velocity of the vehicle body is:

[0088] In this embodiment, let the global coordinates of point A be [X, Y]. T Then the global velocity of point A is:

[0089]

[0090] The angular velocity of the vehicle body is:

[0091] S220, let the distance between point P and point A be d, the curvature of point P be k, and the path length of point P on path C be s. Then the rotational angular velocity of the following coordinate system is... Based on the above data, a kinematic model is constructed:

[0092]

[0093] In this embodiment, let the path length of point P on path C be s, the distance between points A and B be d, and the curvature of point P be k. Then, the following coordinate system... The rotational angular velocity is:

[0094]

[0095] Use V P This indicates that point P is in the moving coordinate system. The speed V A Point A in the moving coordinate system The velocity at which the body descends, according to the kinematic relations of a rigid body, is:

[0096]

[0097] In the formula, in, Represents the transition from the global coordinate system XOY to the following coordinate system Rotation transformation matrix:

[0098]

[0099] Therefore, we get:

[0100]

[0101] Among them, v A Let v be the velocity at point A. B Let θ be the velocity of the steering wheel corresponding to point B, α be the rotation angle of the steering wheel corresponding to point A, β be the rotation angle of the steering wheel corresponding to point B, and let L be the distance between the two steering wheels. m Let θ be the vehicle's heading angle. d For the target attitude angle, I cr As the instantaneous center of rotation, R A Let be the instantaneous rotation radius of the steering wheel at point A.

[0102] Compared to the existing Cartesian coordinate system, the servo coordinate system can more conveniently and intuitively describe the position of a vehicle relative to path C, especially on curved paths.

[0103] When constructing a kinematic model using a servo coordinate system, path curvature information is included, while that is not present in a Cartesian coordinate system. Therefore, this control method can track curves more naturally.

[0104] Reference Figure 2 In some embodiments of the present invention, in S300, the process of determining the control variables and the process of updating the kinematic model include the following specific steps:

[0105] S310, the two steering wheels have the same velocity along the line connecting them, v A cosα=v B cosβ, the velocity v at point A A Set the target speed.

[0106] In this embodiment, under the constraint of no slippage between the two steering wheels, the velocities of the two steering wheels along the connecting line should be the same, and thus:

[0107] v A cosα=v B cosβ (6)

[0108] Therefore:

[0109] v B =v A cosα / cosβ (7)

[0110] In practical applications, the speed of one of the steering wheels is usually set as the target speed. In this embodiment, v is... A Let the target speed of the AGV be a known quantity. Then, we only need to control the rotation angles α and β of the two steering wheels. B It can be calculated using equation (7).

[0111] Analysis of equations (6) and (7) shows that when β = 90°, the denominator is 0, and v B It cannot be calculated. And because v B Since α ≠ 0, then α must be 90°. In this case, the two steering wheels are parallel and perpendicular to the line AB, which is the singular shape of the double-steering-wheel AGV. Furthermore, when α = 90°, if β ≠ 90°, then v must also be true. B =0; if β = 90°, then v B Unable to calculate.

[0112] To overcome the above difficulties, based on the above analysis, the following control strategy is adopted:

[0113] 1) Steering wheels A and B will only be perpendicular to the line AB at the same time. There will never be a situation where only one steering wheel is perpendicular. That is, α and β are either both 90° or neither is 90°.

[0114] 2) When α and β are both 90°, the AGV only performs translational motion, that is, v A =v B .

[0115] To ensure that the designed control method automatically meets the above control strategy when the AGV is in an unusual configuration, without requiring separate processing, the control variables are transformed as follows.

[0116] S320, introduce a new control variable σ, σ = 1 / R A |σ|<1 / L, R A Update the kinematic model to find the instantaneous radius of rotation of the steering wheel at point A:

[0117]

[0118] In this embodiment, the vehicle body rotational angular velocity can also be expressed by the following formula:

[0119]

[0120] Introduce a new control variable σ = 1 / R A Combining equations (2), (6), and (8), we get:

[0121]

[0122] However, equation (9) only holds true when cosβ≠0, that is, β≠90°. Therefore, the control quantity β cannot be directly obtained using equation (9). For this reason, the following constraint is added to σ: |σ|<1 / L.

[0123] After introducing the control variable σ, the kinematic model represented by equation (5) can be updated as follows:

[0124]

[0125] This transforms the control variables α and β into control variables α and σ.

[0126] Reference Figure 2 In some embodiments of the present invention, in S400, the process of obtaining the new control variable at the next moment includes the following specific steps:

[0127] S410, to enable the dual-steering wheel AGV to reach the target attitude angle θ d To perform path tracing, let: θ e =θ m -θ c -θ d .

[0128] In this embodiment, in order for the dual-steering wheel AGV to reach the target attitude angle θ d To perform path tracing, let: θ e =θ m -θ c -θ d After obtaining the global pose of the dual-steering wheel AGV through the navigation and positioning module, and combining it with the path information, d and θ can be calculated. e The control objective is to make d and θ e The convergence to 0 is achieved. The control problem of this invention is a stabilization problem of a nonlinear system, and this invention employs a feedback linearization method.

[0129] S420, in the updated kinematic model Differentiate, and obtain linearization The convergence of d to 0 is based on the two formulas above. Get control quantity After numerical integration This is the control quantity α at the next moment.

[0130] The specific steps of S420 include the following:

[0131] S421, in the updated kinematic model Differentiating gives

[0132]

[0133] Using PD feedback control Linearization, let: d converges to 0, where λ pd , λ dd All are coefficients greater than 0.

[0134] In this embodiment, for formula (10) Differentiating, we get:

[0135]

[0136] Linearize d using PD feedback control, let:

[0137]

[0138] Where, λ pd , λ dd All are coefficients greater than 0. According to the theory of linear systems, equation (12) will cause d to converge to 0.

[0139] S422, combined with formulas (11) and (12), yields Control quantity, for Numerical integration is performed to obtain the control quantity α at the next time step.

[0140] In this embodiment, by combining formulas (11) and (12), we obtain Control the quantity,

[0141]

[0142] The program performs numerical integration to obtain the control quantity α at the next moment.

[0143] The control objective is to make d and θ e The convergence to 0 is achieved. The control problem of this invention is a stabilization problem of a nonlinear system, and this invention employs a feedback linearization method.

[0144] S430, for θ in S410 e Taking the derivative twice, we get Determine the set motion mode to confirm the target attitude angle θ d linearization θ e Converging to 0, according to the two formulas above Get control quantity After numerical integration This is the control quantity σ at the next moment.

[0145] The specific steps for S430 include the following:

[0146] S431, regarding θ in S410 e Taking the derivative twice, we get Where k′ is the rate of change of curvature of the path.

[0147] In this embodiment, for θ e Differentiating, we get:

[0148]

[0149] Again Differentiating, we get:

[0150]

[0151] In the formula, k′ is the rate of change of curvature, which is determined by the tracked path parameters, and is a known quantity. and It is obtained from the updated kinematic model formula (10).

[0152] S432, when it is desired that the dual-steering wheel AGV moves at a fixed angle γ relative to the tangent of the path, then θ d =γ, therefore

[0153] In this embodiment, reference is made to Figure 3 , Given the known quantities, specifically, there are generally two cases: 1) When it is expected that the dual-steering wheel AGV will always move at a fixed angle (denoted as γ) relative to the tangent of the path.

[0154] θ d =γ

[0155] Therefore:

[0156] S433, it is desired that the azimuth angle γ of the dual-steering wheel AGV remains constant regardless of the path direction, then θ d +θ c =γ, therefore

[0157] In this embodiment, reference is made to Figure 3 2) It is expected that the azimuth angle of the AGV will not change with the direction of the path and will always remain unchanged (let's call it γ).

[0158] θ d +θ c =γ

[0159] Therefore:

[0160] S434 utilizes PD feedback control to Linearization, let θ e Converges to 0, where λ pθ , λ dθ All are coefficients greater than zero;

[0161] In this embodiment, PD feedback control is used to... Linearization, let:

[0162]

[0163] Where, λ pθ , λ dθ All are coefficients greater than zero. According to linear system theory, formula (16) will give θ e It converges to 0.

[0164] S435, according to S431 S434 get The control quantity is:

[0165]

[0166] right Numerical integration is performed to obtain the control quantity σ at the next time step.

[0167] In this embodiment, by combining formula (15) and formula (16), we obtain The control quantity is:

[0168]

[0169] In the program Numerical integration is performed to obtain the control quantity σ at the next time step.

[0170] The control objective is to make d and θ e The convergence to 0 is achieved. The control problem of this invention is a stabilization problem of a nonlinear system, and this invention employs a feedback linearization method.

[0171] In some embodiments of the present invention, in S500, the process of obtaining the control variable specifically includes the following steps:

[0172] S510, introduces intermediate control variable β d The variable satisfies the following conditions:

[0173]

[0174] but And for tanβ d Differentiating both sides of the formula yields

[0175] In this embodiment, an intermediate control variable β is introduced. d The variable satisfies the following conditions:

[0176]

[0177] Then we have:

[0178]

[0179] Differentiating both sides of equation (18) yields:

[0180]

[0181] S520, designed with linear proportional feedback λ β For coefficients greater than zero, based on linear proportional feedback and get Control Law:

[0182]

[0183] right Numerical integration is performed to obtain the control variable β at the next time step.

[0184] In this embodiment, a control law is designed so that β closely follows β. d To achieve this goal, the following linear proportional feedback is designed:

[0185]

[0186] Where, λ β For coefficients greater than zero, according to linear system theory, equation (20) will guarantee β-β d It converges to 0, thus achieving β closely following β. d The purpose.

[0187] By combining (19) and (20), we get Control Law:

[0188]

[0189] In the formula, α and β are the rotation angles of the steering wheels at points A and B at the current moment, respectively, obtained through sensor measurements. d It is determined by equation (17). And σ can be determined by S435. This can be determined via S422. In the program... Numerical integration yields the control input β for the next time step.

[0190] S530, replace β in formula (6) with β d And according to cosβ d The control variable v is obtained. B ,

[0191] In this embodiment, formula (6)v A cosα=v B In cosβ, replace β with β dAnd combined with (17), we get:

[0192]

[0193] Formula (22) is the control variable v B The expression for α = 90° and β = 90°, as shown in formulas (22) and (21), does not affect the calculation. Therefore, it is still applicable to the unusual shape of the dual-steering wheel AGV.

[0194] A kinematic model is constructed in a servo coordinate system. By introducing new control variables, the kinematic model is updated, and the updated kinematic model is solved to obtain the control variable formulas (22) and (21), thus obtaining control variables that are not affected by the rotation angle of the two steering wheels. By using the method in this invention to obtain the control variables of the dual-steering-wheel AGV, there is no need to specially handle the singular shape of the AGV, and the AGV can move along the path at any attitude angle.

[0195] According to an embodiment of a second aspect of the present invention, an electronic device includes:

[0196] A memory for storing a program; a processor for executing the program stored in the memory, wherein when the processor executes the program stored in the memory, the processor is used to execute a dual-steering wheel AGV path tracking control method as described in any of the first aspects.

[0197] The processor and memory can be connected via a bus or other means.

[0198] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs, such as the dual-steering wheel AGV path tracking control method described in the embodiments of the present invention. The processor implements the dual-steering wheel AGV path tracking control method of the first aspect of the present invention by running the non-transitory software program and instructions stored in the memory.

[0199] The memory may include a program storage area and a parameter storage area. The program storage area may store the operating system and application programs required for at least one function. The parameter storage area may store the execution of the dual-steering wheel AGV path tracking control method described above. Furthermore, the memory may include high-speed random access memory and non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory may optionally include memory remotely located relative to the processor, which can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0200] According to an embodiment of a third aspect of the present invention, a storage medium is characterized in that it comprises: storing computer-executable instructions for executing the dual-steering wheel AGV path tracking control method of the first aspect of the present invention.

[0201] The non-transient software program and instructions required to implement the above-described terminal selection method are stored in memory. When executed by one or more processors, they are used to implement the dual-steering wheel AGV path tracking control method of the first aspect of the present invention.

[0202] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, parameter structures, program modules, or other parameters). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically include computer-readable instructions, parameter structures, program modules, or other parameters in modulation parameter signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0203] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A path tracking control method for a dual-steering wheel AGV, characterized in that, include: Obtain the currently tracked path and AGV reference point; establish a vehicle coordinate system based on the AGV reference point; obtain orthogonal projection points on the path based on the path and AGV reference point; and establish a follow-up coordinate system based on the orthogonal projection points. Based on the aforementioned follower coordinate system, a kinematic model is constructed in the follower coordinate system; Based on the speed and angle of the two steering wheels, the control variables are determined, the speed of one of the steering wheels is set as the target speed, a new control variable is introduced, and the kinematic model is updated. Based on the path, the updated kinematic model, and the motion mode set by the dual-steering wheel AGV, the new control variables for the next moment are obtained; The control variables are calculated based on the new control variables, target speed, and rotation angles of the two steering wheels at the next moment; The introduction of new control variables and updating of the kinematic model includes: Let the centers of rotation of the two steering wheels be points A and B, respectively. The velocities of the two steering wheels along the line connecting them are the same. ,Will Let the target speed be , where Let B be the speed of the steering wheel; Introducing new control variables The kinematic model is updated as follows: in, Let be the instantaneous rotation radius of the steering wheel at point A; The process of obtaining the new control variable at the next moment specifically includes: make To make the dual-steering wheel AGV reach the target attitude angle To conduct tracking, among which, The vehicle's steering angle. Let P be the tangent angle; In the updated kinematic model Taking the derivative, we get and will Linearization, Converging to zero, according to the derivative... and linearization To obtain the control quantity ,right By performing numerical integration, the control quantity at the next time step is obtained. ; Regarding the Taking the second derivative, we get Determine the target attitude angle based on the set motion mode. ,Will Linearization, and Converging to zero, according to the derivative... and linearization To obtain the control quantity ,right By performing numerical integration, the control quantity at the next time step is obtained. .

2. The path tracking control method for a dual-steering wheel AGV according to claim 1, characterized in that, The process of establishing the following coordinate system specifically includes: Point A is selected as the AGV reference point, and a vehicle coordinate system is established based on the AGV reference point. The x-axis coincides with the line connecting the two steering wheels and points in the forward direction, while the y-axis points to the left. Let the orthogonal projection point of the AGV reference point on the path be point P, and establish a follower coordinate system with the orthogonal projection point as the origin. ,in, The axis points tangentially to point P. The axis points to the left.

3. The path tracking control method for a dual-steering wheel AGV according to claim 2, characterized in that, The construction of the kinematic model specifically includes: Get the global coordinates of point A According to the global coordinates The global velocity of point A is: The angular velocity of the vehicle body is: ; Get the distance from point P to point A Let the curvature at point P be k, and the path length traversed by point P on the path be s. Then, obtain the rotational angular velocity of the moving coordinate system. , And according to the rotational angular velocity The kinematic model in the following coordinate system is obtained by transformation: in, Let A be the speed of the steering wheel. These are the rotation angles of the steering wheel at point A and point B, respectively. This is the distance between the two steering wheels.

4. The path tracking control method for a dual-steering wheel AGV according to claim 1, characterized in that, The control quantity at the next moment The specific process of obtaining it includes: Regarding the Differentiation yields , Using PD feedback control Linearization, let: ,Will Converging to zero, where, , All are coefficients greater than zero; According to the derivative and linearization ,get The control quantity is: right By performing numerical integration, the control quantity at the next time step is obtained. .

5. The path tracking control method for a dual-steering wheel AGV according to claim 4, characterized in that, The control quantity at the next moment The specific process of obtaining it includes: right Taking the second derivative, we get , ,in, The rate of change of curvature of the path; When the set motion mode is tangential to the path at a fixed angle During exercise, ,thereby ; When the set motion mode is the azimuth angle of the AGV If it does not change with the direction of the path and remains unchanged, then ,thereby ; Using PD feedback control Linearization, let ,Will Converging to zero, where, , All are coefficients greater than zero; According to the derivative and linearization ,get The control quantity is: right By performing numerical integration, the control quantity at the next time step is obtained. .

6. The path tracking control method for a dual-steering wheel AGV according to claim 5, characterized in that, The process of obtaining the control variables specifically includes: Introducing intermediate control variables And satisfy: Then there is And by differentiating both sides, we get , ; Design linear proportional feedback ), For coefficients greater than zero, based on the linear proportional feedback and ,get Control Law: right Perform numerical integration to obtain the control variable at the next time step. ; Will In Replace with and according to To obtain control variables , .

7. An electronic device, characterized in that, include: Memory, used to store programs; A processor is configured to execute a program stored in the memory, wherein when the processor executes the program stored in the memory, the processor is configured to perform a dual-steering wheel AGV path tracking control method as described in any one of claims 1 to 6.

8. A storage medium, characterized in that, include: The device stores computer-executable instructions for performing a dual-steering wheel AGV path tracking control method as described in any one of claims 1 to 6.

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