A method and system for tracking a bidirectional travel path of an articulated steering vehicle

Abstract

The application provides a kind of articulated steering vehicle bidirectional travel path tracking control method and system, it is related to the motion control technical field of unmanned vehicle, including: the hardware platform of articulated steering car bidirectional travel is constructed;The reference point of articulated steering car forward travel path is selected;The reference point of articulated steering car reverse travel path is selected;Based on hardware platform and reference point, the bidirectional travel path tracking control of articulated steering car is carried out.The application proposes a hardware platform setting method, solves the problem that the existing articulated steering vehicle unmanned system cannot provide rear axle position and attitude information, secondly proposes a switching reference point selection method under bidirectional travel working condition, solves the problem of different reference points caused by different control points when forward travel and reverse travel.A kind of path tracking control framework is proposed, with rear axle midpoint as control point under reverse travel working condition, to solve the problem of realizing reverse path tracking without changing the positive direction of positioning system.

Description

Technical Field

[0001] This invention relates to the field of motion control technology for unmanned vehicles, and in particular to a method and system for tracking and controlling the bidirectional driving path of an articulated steering vehicle. Background Technology

[0002] Articulated steering vehicles, often simply called articulated vehicles, are also known as Articulated Steering Vehicles or simply Articulated Vehicles. These vehicles achieve steering by actively changing the articulation angle (or bend angle) between the front and rear bodies, fundamentally different from semi-trailers and full trailers (CN115950442A) where the front wheels steer and the rear body follows. Regarding path tracking control for these vehicles, some research has been conducted (Bai G, Liu L, Meng Y, et al. Path tracking of mining vehicles based on nonlinear model predictive control[J]. Applied...). Sciences, 2019, 9(7): 1372; Meng Yu, Wang Yu, Gu Qing, et al. LQR-GA path tracking control for articulated vehicles based on pre-predicted pose information [J]. Transactions of the Chinese Society for Agricultural Machinery, 2018, 49(6): 375-384; Shao Junkai, Zhao Xuan, Yang Jue, et al. Reinforcement learning path tracking control algorithm for unmanned articulated vehicles [J]. Transactions of the Chinese Society for Agricultural Machinery, 2017, 48(3): 376-382; Zhao Xuan, Yang Jue, Zhang Wenming, et al. Sliding mode trajectory of agricultural wheeled articulated vehicles Tracking control algorithm [J]. Transactions of the Chinese Society of Agricultural Engineering, 2015, 31(10): 198-203; Meng Yu, Gan Xin, Bai Guoxing. Path tracking prediction control of articulated vehicles for underground mining based on pre-aiming distance [J]. Journal of Engineering Science, 2019, 41(5): 662-671; CN103197675A; CN111538331A). These research results are of great significance for path tracking control of articulated steering vehicles, but the problem of articulated steering vehicles needing to travel in both directions has not yet been solved. Specifically, existing path tracking control methods for articulated steering vehicles all use the center of the front axle of the vehicle as the control point. When traveling in the opposite direction, the path tracking control will experience dangerous situations such as error divergence. Summary of the Invention

[0003] This invention provides a bidirectional driving path tracking control method and system for articulated steering vehicles, which solves the problem that existing articulated steering vehicle path tracking control methods all use the center of the front axle of the vehicle as the control point, and when driving in the opposite direction, the path tracking control will have dangerous situations such as error divergence.

[0004] To achieve the aforementioned objectives, the present invention provides the following technical solution: a method for tracking and controlling the bidirectional driving path of an articulated steering vehicle, characterized in that the steps include:

[0005] S1. Construct a hardware platform for the articulated steering vehicle to travel in both directions;

[0006] S2. Select reference points for the forward travel path of the articulated steering vehicle; select reference points for the reverse travel path of the articulated steering vehicle.

[0007] S3. Based on the hardware platform and reference points, perform bidirectional driving path tracking control for articulated steering vehicles.

[0008] Preferably, in step S1, constructing the hardware platform for bidirectional travel of the articulated steering vehicle includes:

[0009] A front axle center positioning system is installed on the front of the vehicle body, and a rear axle center positioning system is installed on the rear of the vehicle body, along with hinge angle and hinge angular velocity sensors at the hinge points.

[0010] Preferably, the output data of the front axle center positioning system includes: the horizontal and vertical coordinates of the front axle center in the global coordinate system and the heading angle of the front vehicle body, as well as the longitudinal velocity and yaw rate of the front vehicle body in the front axle coordinate system.

[0011] The positive longitudinal direction of the front axle coordinate system is the forward direction of the front vehicle body, the positive lateral direction is the left side of the forward direction of the front vehicle body, and the positive directions of the front vehicle body's heading angle and yaw rate are counterclockwise.

[0012] Preferably, the output data of the rear axle center positioning system includes: the abscissa, ordinate, and heading angle of the rear axle center in the global coordinate system, the longitudinal velocity of the rear vehicle body, and the yaw rate of the rear vehicle body in the rear axle coordinate system.

[0013] The positive longitudinal direction of the rear axle coordinate system is the forward direction of the rear vehicle body, the positive lateral direction is the left side of the forward direction of the rear vehicle body, and the positive directions of the rear vehicle body's heading angle and yaw rate are counterclockwise.

[0014] The articulation angle and the positive direction of the articulation angular velocity are counterclockwise. The articulation angle is the difference between the heading angle of the front vehicle and the heading angle of the rear vehicle.

[0015] Preferably, in step S2, selecting reference points for the forward travel path of the articulated steering vehicle includes:

[0016] When traveling in the forward direction, a reference point is selected by solving the optimization function as shown in formula (1) below:

[0017]

[0018] In the formula, x represents the horizontal coordinate, y represents the vertical coordinate, the subscript f represents the center of the front axle, and the subscript i represents the i-th point in the reference path point list;

[0019] When the i-th point is closest to the center of the front axle, then point i is the reference point for forward driving.

[0020] Preferably, in step S2, selecting reference points for the reverse travel path of the articulated steering vehicle includes:

[0021] When driving in the opposite direction, a reference point is selected by solving the optimization function as shown in formula (2) below:

[0022]

[0023] In the formula, the subscript r represents the center of the rear axle;

[0024] When the j-th point is closest to the center of the rear axle, the j-th point is the reference point for reverse driving.

[0025] Preferably, step S2 further includes:

[0026] Based on the aforementioned reverse driving condition reference point, a series of calculation points for the reverse driving condition are selected;

[0027] The conditions for selecting the calculation point series for the reverse driving condition include:

[0028] When driving in the opposite direction, the forward direction of the reference path provided by the path planning system must be set to be consistent with the reverse driving direction of the articulated steering vehicle.

[0029] When a reverse driving command is received, the longitudinal speed is inverted, and the longitudinal speed is calculated as a positive value throughout all path tracking control processes;

[0030] Before being sent to the actuator, the longitudinal speed is inverted to achieve reverse travel.

[0031] Preferably, in step S3, based on the hardware platform and the reference point, bidirectional driving path tracking control of the articulated steering vehicle is performed, including:

[0032] When traveling in the forward direction, the articulated steering vehicle is controlled using traditional control methods for path tracking.

[0033] When driving in the opposite direction, the articulated steering vehicle is controlled by path tracking using a linear quadratic adjustable LQR control or model predictive control algorithm based on the kinematic model of the articulated steering vehicle.

[0034] Preferably, during reverse driving, based on the kinematic model of the articulated steering vehicle, linear quadratic adjustable LQR control or model predictive control algorithms are used to perform path tracking control on the articulated steering vehicle, including:

[0035] Using the original front axle as the rear axle during actual driving and the original rear axle as the front axle during actual driving, based on the classic articulated steering vehicle kinematic model, the variables in the model are transformed, and the reference model should be as shown in the following formula (3):

[0036]

[0037] Where θ represents the heading angle, l represents the distance from the axle to the articulation point, γ represents the articulation angle, ω represents the angular velocity, subscript of represents the original front axle, subscript or represents the original rear axle; subscript pr represents the value measured by the positioning system on the original rear axle; subscript p represents the value measured by the positioning system.

[0038] Substituting the reference model into the linear quadratic adjustable LQR control or model predictive control calculation, the reverse driving path tracking control of the articulated steering vehicle is completed.

[0039] A bidirectional driving path tracking control system for articulated steering vehicles, the system being used in the aforementioned bidirectional driving path tracking control method for articulated steering vehicles, the system comprising:

[0040] The platform building module is used to build the hardware platform for the articulated steering vehicle to travel in both directions;

[0041] The reference point selection module is used to select reference points for the forward travel path of the articulated steering vehicle and to select reference points for the reverse travel path of the articulated steering vehicle.

[0042] The tracking control module is used to perform bidirectional driving path tracking control of the articulated steering vehicle based on the hardware platform and the reference point.

[0043] On one hand, an electronic device is provided, comprising a processor and a memory, wherein the memory stores at least one instruction, which is loaded and executed by the processor to implement the above-described articulated steering vehicle bidirectional driving path tracking control method.

[0044] On the one hand, a computer-readable storage medium is provided, wherein at least one instruction is stored in the storage medium, the at least one instruction being loaded and executed by a processor to implement the above-described articulated steering vehicle bidirectional driving path tracking control method.

[0045] The above technical solution has at least the following advantages compared with the existing technology:

[0046] The above solution first proposes a hardware platform setup method to address the problem that existing articulated steering vehicle autonomous driving systems cannot provide rear axle position and attitude information. Second, it proposes a method for selecting switching reference points under bidirectional driving conditions to solve the problem of different reference points caused by different control points when driving forward and backward. Finally, it proposes a path tracking control framework with the rear axle midpoint as the control point under reverse driving conditions to solve the problem of achieving reverse path tracking without changing the positive direction of the positioning system. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a schematic flowchart of the bidirectional driving path tracking control method for articulated steering vehicles provided in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the positioning system layout provided in an embodiment of the present invention;

[0050] Figure 3 This is a schematic diagram of the positioning system provided in an embodiment of the present invention in the forward direction;

[0051] Figure 4 This is a schematic diagram of parameter transformation provided in an embodiment of the present invention.

[0052] Figure 5 This is a block diagram of the articulated steering vehicle bidirectional driving path tracking control system provided in an embodiment of the present invention;

[0053] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0055] This invention addresses the problem that existing articulated steering vehicle path tracking control methods all use the center of the vehicle's front axle as the control point, which can lead to dangerous situations such as error divergence during reverse driving. The invention provides a bidirectional path tracking control method and system for articulated steering vehicles.

[0056] like Figure 1 As shown, this embodiment of the invention provides a bidirectional driving path tracking control method for articulated steering vehicles, which can be implemented by electronic devices. Figure 1 The flowchart shown is for a bidirectional driving path tracking control method for articulated steering vehicles. The processing flow of this method may include the following steps:

[0057] S101. Construct a hardware platform for bidirectional operation of articulated steering vehicles.

[0058] In one feasible implementation, step S101 involves constructing a hardware platform for bidirectional movement of the articulated steering vehicle, including:

[0059] A front axle center positioning system is installed in the front of the vehicle body, and a rear axle center positioning system is installed in the rear of the vehicle body, along with hinge angle and hinge angular velocity sensors at the hinge points, such as... Figure 2 As shown.

[0060] In one feasible implementation, in order to achieve bidirectional driving path tracking control, the traditional hardware platform must be improved by adding a positioning system at the center of the rear axle. This positioning system provides the horizontal and vertical coordinates and heading angle of the rear axle center in the global coordinate system, the longitudinal velocity and yaw rate in the rear axle coordinate system, and the hinge angle and hinge rate at the hinge point.

[0061] In one feasible implementation, a positioning system added at the center of the rear axle is related to the operating conditions of the articulated steering vehicle.

[0062] If articulated steering vehicles are used in open-pit environments such as open-pit mines, differential GPS can be used as the positioning system.

[0063] If articulated steering vehicles are used in enclosed environments such as mines and underground operations, a laser positioning system can be used, as shown in CN104750115B.

[0064] In one feasible implementation, the output data of the front axle center positioning system includes: the abscissa, ordinate and heading angle of the front axle center in the global coordinate system, the longitudinal velocity of the front vehicle body and the yaw rate of the front vehicle body in the front axle coordinate system.

[0065] The positive longitudinal direction of the front axle coordinate system is the forward direction of the front vehicle body, the positive lateral direction is the left side of the forward direction of the front vehicle body, and the positive directions of the front vehicle body's heading angle and yaw rate are counterclockwise.

[0066] In one feasible implementation, the output data of the rear axle center positioning system includes: the abscissa, ordinate and heading angle of the rear axle center in the global coordinate system, the longitudinal velocity of the rear vehicle body and the yaw rate of the rear vehicle body in the rear axle coordinate system.

[0067] The positive longitudinal direction of the rear axle coordinate system is the forward direction of the rear vehicle body, the positive lateral direction is the left side of the forward direction of the rear vehicle body, and the positive directions of the rear vehicle body's heading angle and yaw rate are counterclockwise.

[0068] The articulation angle and the positive direction of the articulation angular velocity are counterclockwise; the articulation angle is the difference between the heading angle of the front vehicle body and the heading angle of the rear vehicle body.

[0069] In one feasible implementation, in order to achieve bidirectional driving path tracking control, the traditional hardware platform must be improved by adding a positioning system at the center of the rear axle. This positioning system provides the horizontal and vertical coordinates and heading angle of the rear axle center in the global coordinate system, the longitudinal velocity and yaw rate in the rear axle coordinate system, and the hinge angle and hinge rate at the hinge point.

[0070] The positioning system added to the center of the rear axle is related to the operating conditions of articulated steering vehicles.

[0071] If articulated steering vehicles are used in open-pit environments such as open-pit mines, differential GPS can be used as the positioning system.

[0072] If articulated steering vehicles are used in enclosed environments such as mines and underground operations, a laser positioning system can be used for the positioning system.

[0073] In one feasible implementation, the positioning system needs to determine the positive directions of the front axle coordinate system and the rear axle coordinate system, such as... Figure 3 As shown. In the front axle coordinate system, the positive longitudinal direction is the forward direction of the front vehicle body, the positive lateral direction is to the left of the forward direction of the front vehicle body, and the positive direction of the yaw rate is counterclockwise. In the rear axle coordinate system, the positive longitudinal direction is the forward direction of the rear vehicle body, the positive lateral direction is to the left of the forward direction of the rear vehicle body, and the positive direction of the yaw rate is counterclockwise. The positive directions of the heading angle, articulation angle, and articulation rate are counterclockwise. The articulation angle refers to the difference between the heading angle of the front vehicle body and the heading angle of the rear vehicle body.

[0074] S102. Select reference points for the forward travel path of the articulated steering vehicle; select reference points for the reverse travel path of the articulated steering vehicle.

[0075] In one feasible implementation, since the control points are different when performing bidirectional driving tasks, it is necessary to switch the reference point selection procedure before performing driving tasks in different directions, such as... Figure 4 As shown.

[0076] In one feasible implementation, step S102 involves selecting a reference point for the forward travel path of the articulated steering vehicle, including:

[0077] When traveling in the forward direction, a reference point is selected by solving the optimization function as shown in formula (1) below:

[0078]

[0079] In the formula, x represents the horizontal coordinate, y represents the vertical coordinate, the subscript f represents the center of the front bridge, and the subscript i represents the i-th point in the reference path point list.

[0080] When the i-th point is closest to the center of the front axle, then point i is the reference point for forward driving.

[0081] In one feasible implementation, step S102 involves selecting a reference point for the reverse travel path of the articulated steering vehicle, including:

[0082] When driving in the opposite direction, a reference point is selected by solving the optimization function as shown in formula (2) below:

[0083]

[0084] In the formula, the subscript r represents the center of the rear axle;

[0085] When the j-th point is closest to the center of the rear axle, the j-th point is the reference point for reverse driving.

[0086] In one feasible implementation, based on the above, in order to improve real-time performance, a prediction-based reference point selection method can be further adopted, as described in CN112859863B.

[0087] In one feasible implementation, if a prediction-based reference point selection method or a path tracking control method with pre-aiming points is used, there are several key nodes in the calculation point series for the reverse driving condition:

[0088] First, when driving in the opposite direction, the forward direction of the reference path given by the path planning system must be set to be consistent with the reverse driving direction of the articulated steering vehicle.

[0089] Then, upon receiving a reverse driving command, the longitudinal speed is inverted. That is, the longitudinal speed is calculated as a positive value throughout all path tracking control processes;

[0090] Finally, before sending the signal to the actuator, the longitudinal speed is inverted to achieve reverse travel.

[0091] S103. Based on the hardware platform and reference points, perform bidirectional driving path tracking control for the articulated steering vehicle.

[0092] In one feasible implementation, step S103 involves performing bidirectional driving path tracking control of the articulated steering vehicle based on the hardware platform and reference points, including:

[0093] When traveling in the forward direction, the articulated steering vehicle is controlled using traditional control methods for path tracking.

[0094] When using a prediction-based reference point selection method or a path tracking control method with pre-aiming points, there are several key nodes in the calculation point series for reverse driving conditions. During reverse driving, the forward direction of the reference path given by the path planning system is consistent with the reverse driving direction of the articulated steering vehicle. When the articulated steering vehicle receives a reverse driving command, it reverses its longitudinal speed. In all reverse driving path tracking control processes, the longitudinal speed is calculated as a positive value. Before finally sending it to the actuator, it is reversed again to control the articulated steering vehicle to drive in reverse.

[0095] In one feasible implementation, the path tracking control algorithm under forward driving conditions can adopt existing algorithms.

[0096] In the reverse driving condition, the rear axle center is used as the control point, and the speed control uses the rear axle longitudinal speed as the control target. In the path tracking control, the longitudinal speed is reversed, that is, the longitudinal speed is calculated as a positive value. The measured articulation angle and articulation angular velocity values ​​are reversed, so that the measured rear axle center heading angle is increased or decreased by 180°, so that the difference between the rear axle center heading angle and the reference path heading angle is less than 90°. The heading of the reference path given by the path planning system is consistent with the reverse driving direction of the articulated steering vehicle.

[0097] In one feasible implementation, under reverse driving conditions, control algorithms such as LQR (linear quadratic regulator) and model predictive control can be used.

[0098] Furthermore, these control methods require a kinematic model of articulated steering vehicles as their theoretical basis.

[0099] In the reverse driving condition, the original front axle in the forward driving condition becomes the de facto rear axle, and the original rear axle becomes the de facto front axle. However, the kinematic characteristics of the articulated steering vehicle remain unchanged. Therefore, the derivation is still based on the classic kinematic model of the articulated steering vehicle.

[0100] The classic kinematic model of an articulated steering vehicle is:

[0101]

[0102] In the formula, θ represents the heading angle, l represents the distance from the axle to the articulation point, γ represents the articulation angle, ω represents the angular velocity, the subscript f represents the front axle, and the subscript r represents the rear axle.

[0103] In the reverse driving condition, the original front axle becomes the de facto rear axle, and the original rear axle becomes the de facto front axle. The variables in the above model change as follows:

[0104]

[0105] In the formula, the subscript of indicates the original front axle, and the subscript or indicates the original rear axle.

[0106] Considering that the positive direction of the rear axle coordinate system is the direction of the vehicle's forward movement, when traveling in the opposite direction, the longitudinal speed of the control system is inverted, that is, the longitudinal speed read by the control system is:

[0107] v or =-v pr

[0108] In the formula, the subscript pr represents the value measured by the positioning system on the original rear axle.

[0109] In addition, when the forward direction is opposite to the positive direction of the rear axle coordinate system of the positioning system, the hinge angle and hinge angular velocity read by the control system should also be the opposite values ​​of the positioning system measurements:

[0110]

[0111] In the formula, the subscript p represents the value measured by the positioning system.

[0112] In reverse driving conditions, the forward direction of the reference path given by the path planning system is consistent with the reverse driving direction of the articulated steering vehicle. At this time, the difference between the forward direction of the reference path and the heading angle given by the positioning system is too large. If the heading angle given by the positioning system is used directly, it will cause the articulated steering vehicle to turn around, resulting in problems such as collision with the tunnel wall or failure to align the working mechanism with the work object.

[0113] To solve the above problem, the heading angle given by the positioning system is processed as follows:

[0114]

[0115] In the formula, the subscript ref indicates a reference value.

[0116] That is, take the original rear axle heading angle increased or decreased by 180°, and take the absolute value of the difference between the result and the heading angle of the reference path that is less than or equal to 90° as the heading angle of the model front axle in the control system.

[0117] Substituting the above changes into the classic model:

[0118]

[0119] By substituting this model into the control algorithm, reverse path tracking control of articulated steering vehicles can be achieved. LQR, model predictive control, and other control methods are all publicly known and are not claimed in this patent.

[0120] After the control algorithm completes its calculations, the longitudinal velocity is inverted and transmitted as a negative value to the actuator. The obtained articulated angular velocity is also inverted and transmitted to the actuator, thus completing the reverse path tracking control.

[0121] In this embodiment of the invention, a hardware platform setting method is first proposed to solve the problem that the existing articulated steering vehicle autonomous driving system cannot provide rear axle position and attitude information. Secondly, a switching reference point selection method under bidirectional driving conditions is proposed to solve the problem of different reference points caused by different control points when driving forward and backward. Finally, a path tracking control framework with the rear axle midpoint as the control point is proposed under reverse driving conditions to solve the problem of achieving reverse path tracking without changing the positive direction of the positioning system.

[0122] Figure 5 This is a schematic diagram of a bidirectional driving path tracking control system for an articulated steering vehicle according to the present invention. The system 200 is used in the above-described bidirectional driving path tracking control method for articulated steering vehicles, and the system 200 includes:

[0123] Platform building module 210 is used to build a hardware platform for bidirectional travel of the articulated steering vehicle;

[0124] The reference point selection module 220 is used to select reference points for the forward travel path of the articulated steering vehicle and to select reference points for the reverse travel path of the articulated steering vehicle.

[0125] The tracking control module 230 is used to perform bidirectional driving path tracking control of the articulated steering vehicle based on the hardware platform and the reference point.

[0126] Preferably, the platform construction module 210 is used to set a front axle center positioning system on the front vehicle body and a rear axle center positioning system on the rear vehicle body.

[0127] Preferably, the output data of the front axle center positioning system includes: the abscissa, ordinate and heading angle of the front axle center in the global coordinate system, the longitudinal velocity of the front vehicle body and the yaw rate of the front vehicle body in the front axle coordinate system;

[0128] The positive longitudinal direction of the front axle coordinate system is the forward direction of the front vehicle body, the positive lateral direction is the left side of the forward direction of the front vehicle body, and the positive directions of the front vehicle body's heading angle and yaw rate are counterclockwise.

[0129] Preferably, the output data of the rear axle center positioning system includes: the abscissa, ordinate, and heading angle of the rear axle center in the global coordinate system, the longitudinal velocity of the rear vehicle body, and the yaw rate of the rear vehicle body in the rear axle coordinate system.

[0130] The positive longitudinal direction of the rear axle coordinate system is the forward direction of the rear vehicle body, the positive lateral direction is the left side of the forward direction of the rear vehicle body, and the positive directions of the rear vehicle body's heading angle and yaw rate are counterclockwise.

[0131] The articulation angle and the positive direction of the articulation angular velocity are counterclockwise; the articulation angle is the difference between the heading angle of the front vehicle body and the heading angle of the rear vehicle body.

[0132] Preferably, the reference point selection module 220 is used to select a reference point by solving an optimization function as shown in formula (1) when driving in the forward direction:

[0133]

[0134] In the formula, x represents the horizontal coordinate, y represents the vertical coordinate, the subscript f represents the center of the front bridge, and the subscript i represents the i-th point in the reference path point list.

[0135] When the i-th point is closest to the center of the front axle, then point i is the reference point for forward driving.

[0136] Preferably, the reference point selection module 220 is used to select a reference point by solving an optimization function as shown in formula (2) below when driving in the opposite direction:

[0137]

[0138] In the formula, the subscript r represents the center of the rear axle;

[0139] When the j-th point is closest to the center of the rear axle, the j-th point is the reference point for reverse driving.

[0140] Preferably, the reference point selection module 220 is used to select a series of calculation points for the reverse driving condition based on the reference point for the reverse driving condition.

[0141] The conditions for selecting the calculation point series for the reverse driving condition include:

[0142] When driving in the opposite direction, the forward direction of the reference path provided by the path planning system must be set to be consistent with the reverse driving direction of the articulated steering vehicle.

[0143] When a reverse driving command is received, the longitudinal speed is inverted, and the longitudinal speed is calculated as a positive value throughout all path tracking control processes;

[0144] Before being sent to the actuator, the longitudinal speed is inverted to achieve reverse travel.

[0145] Preferably, the tracking control module 230 is used to perform path tracking control of the articulated steering vehicle using conventional control methods when driving forward;

[0146] When driving in the opposite direction, the articulated steering vehicle is controlled by path tracking using a linear quadratic adjustable LQR control or model predictive control algorithm based on the kinematic model of the articulated steering vehicle.

[0147] Preferably, during reverse driving, based on the kinematic model of the articulated steering vehicle, linear quadratic adjustable LQR control or model predictive control algorithms are used to perform path tracking control on the articulated steering vehicle, including:

[0148] Using the original front axle as the rear axle during actual driving and the original rear axle as the front axle during actual driving, and applying the variables in the model based on the classic articulated steering vehicle kinematics model, the reference model should be as shown in the following formula (3):

[0149]

[0150] Where θ represents the heading angle, l represents the distance from the axle to the articulation point, γ represents the articulation angle, ω represents the angular velocity, subscript of represents the original front axle, subscript or represents the original rear axle; subscript pr represents the value measured by the positioning system on the original rear axle; subscript p represents the value measured by the positioning system.

[0151] Substituting the reference model into the linear quadratic adjustable LQR control or model predictive control calculation, the reverse driving path tracking control of the articulated steering vehicle is completed.

[0152] In this embodiment of the invention, a hardware platform setting method is first proposed to solve the problem that the existing articulated steering vehicle autonomous driving system cannot provide rear axle position and attitude information. Secondly, a switching reference point selection method under bidirectional driving conditions is proposed to solve the problem of different reference points caused by different control points when driving forward and backward. Finally, a path tracking control framework with the rear axle midpoint as the control point is proposed under reverse driving conditions to solve the problem of achieving reverse path tracking without changing the positive direction of the positioning system.

[0153] Figure 6 This is a schematic diagram of the structure of an electronic device 300 provided in an embodiment of the present invention. The electronic device 300 can vary considerably due to differences in configuration or performance. It may include one or more central processing units (CPUs) 301 and one or more memories 302. The memories 302 store at least one instruction, which is loaded and executed by the processors 301 to implement the steps of the following method for tracking and controlling the bidirectional driving path of an articulated steering vehicle:

[0154] S1. Construct a hardware platform for the articulated steering vehicle to travel in both directions;

[0155] S2. Select reference points for the forward travel path of the articulated steering vehicle; select reference points for the reverse travel path of the articulated steering vehicle.

[0156] S3. Based on the hardware platform and the reference point, perform bidirectional driving path tracking control for the articulated steering vehicle.

[0157] In an exemplary embodiment, a computer-readable storage medium is also provided, such as a memory including instructions that can be executed by a processor in a terminal to complete the aforementioned bidirectional driving path tracking control method for articulated steering vehicles. For example, the computer-readable storage medium may be a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, or optical data storage device.

[0158] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware or by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

Claims

1. A method for tracking and controlling the bidirectional travel path of an articulated steering vehicle, characterized in that, The method steps include: S1. Constructing a hardware platform for bidirectional operation of articulated steering vehicles: A front axle center positioning system is installed on the front of the vehicle body, a rear axle center positioning system is installed on the rear of the vehicle body, and hinge angle and hinge angular velocity sensors are installed at the hinge points. The output data of the front axle center positioning system includes: the horizontal and vertical coordinates of the front axle center in the global coordinate system, the heading angle of the front vehicle body, the longitudinal velocity of the front vehicle body and the yaw rate of the front vehicle body in the front axle coordinate system. The positive longitudinal direction of the front axle coordinate system is the forward direction of the front vehicle body, the positive lateral direction is the left side of the forward direction of the front vehicle body, and the positive directions of the front vehicle body heading angle and the front vehicle body yaw rate are counterclockwise. The output data of the rear axle center positioning system includes: the horizontal and vertical coordinates of the rear axle center in the global coordinate system, the heading angle of the rear vehicle body, the longitudinal velocity of the rear vehicle body in the rear axle coordinate system, and the yaw rate of the rear vehicle body. The positive longitudinal direction of the rear axle coordinate system is the forward direction of the rear vehicle body, the positive lateral direction is the left side of the forward direction of the rear vehicle body, and the positive directions of the rear vehicle body heading angle and the rear vehicle body yaw rate are counterclockwise. The articulation angle is the difference between the heading angle of the front vehicle body and the heading angle of the rear vehicle body. The positive direction of the articulation angle and the positive direction of the articulation angular velocity are counterclockwise. S2. Selecting reference points for the forward travel path of the articulated steering vehicle; selecting reference points for the reverse travel path of the articulated steering vehicle, including: When driving in the opposite direction, the reference point is selected by solving the optimization function as shown in formula (2) below: （2） In the formula, Represents the x-axis, Represents the vertical axis, subscript Indicates the center of the rear axle, subscript Indicates the first in the reference path point column One point; When the When the point is closest to the center of the rear axle The point is the reference point for reverse driving; Step S2 further includes: selecting a series of calculation points for the reverse driving condition based on the reverse driving reference point; The conditions for selecting the calculation point series for the reverse driving condition include: When driving in the opposite direction, the forward direction of the reference path provided by the path planning system must be set to be consistent with the reverse driving direction of the articulated steering vehicle. When a reverse driving command is received, the longitudinal speed is inverted, and the longitudinal speed is calculated as a positive value throughout all path tracking control processes; Before being sent to the actuator, the longitudinal speed is inverted to achieve reverse travel; S3. Based on the hardware platform and the reference point, perform bidirectional driving path tracking control for the articulated steering vehicle; wherein, during reverse driving, using the kinematic model of the articulated steering vehicle as the theoretical basis, employ linear quadratic adjustable LQR control or model predictive control algorithms to perform path tracking control for the articulated steering vehicle, including: Using the front axle during forward driving as the rear axle during actual driving, and the rear axle during forward driving as the front axle during actual driving, based on the classic articulated steering vehicle kinematic model, the variables in the model are transformed, and the reference model should be as shown in the following formula (3): （3） in, Indicates the heading angle. This indicates the distance from the axle to the articulation point. Indicates the hinge angle. Indicates angular velocity, subscript Indicates the front axle when traveling in the forward direction, subscript Indicates the rear axle when traveling in the forward direction; subscript This indicates the value measured by the positioning system on the rear axle when the vehicle is traveling in the forward direction; subscript This represents the value measured by the positioning system; Substituting the reference model into a linear quadratic adjustable LQR control or model predictive control algorithm completes the reverse driving path tracking control for articulated steering vehicles.

2. The method according to claim 1, characterized in that, In step S2, selecting reference points for the forward travel path of the articulated steering vehicle includes: When traveling in the forward direction, the reference point is selected by solving the optimization function as shown in formula (1) below: （1） In the formula, the subscript Indicates the center of the front axle; when the first i When a point is closest to the center of the front axle, then i The point is the reference point for forward driving.

3. According to the method of claim 2, in step S3, when driving forward, a conventional control method is used to perform path tracking control on the articulated steering vehicle.

4. A bidirectional driving path tracking control system for articulated steering vehicles, characterized in that, The system is used to execute the bidirectional driving path tracking control method for articulated steering vehicles as described in any one of claims 1 to 3, the system comprising: The platform building module is used to build the hardware platform for the articulated steering vehicle to travel in both directions; The reference point selection module is used to select reference points for the forward travel path of the articulated steering vehicle and to select reference points for the reverse travel path of the articulated steering vehicle. The tracking control module is used to perform bidirectional driving path tracking control of the articulated steering vehicle based on the hardware platform and the reference point.

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