A dual-mode coupled steer-by-wire system and a steering angle tracking control method thereof

Abstract

The application provides a dual-mode coupled steer-by-wire system and a steering angle tracking control method thereof.The dual-mode coupled steer-by-wire system comprises a steering motor module, a steering transmission module, a commutator, an electromagnetic clutch, a steering angle sensor and an ECU control module.The commutator comprises a commutator A and a commutator B, and is used for changing the output torque direction of the steering motor module.The electromagnetic clutch is used for connecting the commutator A and the commutator B, and realizes the power disconnection or connection between the commutator A and the commutator B.The steering angle sensor is used for obtaining the steering angle of a wheel and transmitting the steering angle to the ECU control module.The ECU control module is connected with the steering angle sensor, a steering motor A driver and a steering motor B driver respectively, and is used for controlling the electromagnetic clutch, the steering motor A driver and the steering motor B driver to work according to the sensing signal of the steering angle sensor.The system improves the steering flexibility and structural reliability of the steer-by-wire system.

Description

Technical Field

[0001] This invention relates to the field of automotive steer-by-wire technology, and in particular to a dual-mode coupled steer-by-wire system and its steering angle tracking control method. Background Technology

[0002] With the deep integration of automation, intelligence, and the automotive industry, autonomous vehicles have garnered widespread attention and research from academia and industry due to their advantages in traffic safety, energy conservation, and time efficiency. Among these, steer-by-wire systems, as one of the execution systems of autonomous vehicles, overcome the mechanical limitations of traditional steering systems. By adjusting the output torque of the steering motor, the front wheel angle tracks the desired signal, ensuring the autonomous vehicle follows the planned path. Currently, steer-by-wire systems in vehicles generally employ independent steering drive systems to decouple the steering actions of the left and right wheels, considering steering flexibility. To ensure the reliability of the steering structure, redundancy is implemented in the hardware, and dual-motor steer-by-wire systems have also been researched, but their steering flexibility is relatively reduced. To address the functional and hardware conflicts between steering flexibility and steering structure reliability, multi-mode steer-by-wire systems have seen significant research, but their implementation methods are overly complex, requiring excessive hardware, which is detrimental to installation and application in real vehicles.

[0003] Furthermore, the cornering tracking control of multi-mode steer-by-wire systems, which ensures cornering tracking performance during mode switching, also faces some challenges. Currently, most nonlinear control methods are based on model identification and prediction techniques. However, when switching between two or more modes, the different or unknown dynamic models between these modes lead to lags or inaccuracies in model identification and prediction results. This can cause unpredictable step jumps in cornering tracking errors or even non-convergence of the closed-loop system, resulting in serious safety issues for vehicles using multi-mode steer-by-wire systems. Summary of the Invention

[0004] In view of this, the present invention provides a dual-mode coupled steer-by-wire system and its steering angle tracking control method to solve the above problems.

[0005] This invention provides a dual-mode coupled steer-by-wire system, comprising: a steering motor module, a steering transmission module, a commutator, an electromagnetic clutch, a steering angle sensor, and an ECU control module; the steering motor module includes a steering motor A driver and a steering motor B driver; the commutator includes a commutator A and a commutator B, used to change the output torque direction of the steering motor module; the electromagnetic clutch is used to connect the commutator A and the commutator B, realizing the disconnection or connection of power between the commutator A and the commutator B; the steering angle sensor is used to obtain the wheel angle and transmit it to the ECU control module; the ECU control module is connected to the steering angle sensor, the steering motor A driver, and the steering motor B driver respectively, and is used to control the operation of the electromagnetic clutch, the steering motor A driver, and the steering motor B driver according to the sensing signal of the steering angle sensor.

[0006] In another implementation of the present invention, the steering motor module further includes a steering motor A, a steering motor A reducer, a steering motor B, and a steering motor B reducer; the commutator has three torque input or output terminals, namely terminal a, terminal b, and terminal c; the steering motor A is connected to the a-terminal shaft of the commutator A via the steering motor A reducer, and the b-terminal shaft of the commutator A is connected to the left end of the electromagnetic clutch; the steering motor B is connected to the a-terminal shaft of the commutator B via the steering motor B reducer, and the b-terminal shaft of the commutator B is connected to the right end of the electromagnetic clutch.

[0007] In another implementation of the present invention, the steering transmission module includes a pinion A, a rack A, a steering tie rod A, a wheel A, a pinion B, a rack B, a steering tie rod B, and a wheel B; the pinion A is connected to the c-end shaft of the commutator A, the pinion A meshes with the rack A, the rack A is connected to the steering tie rod A, and the other end of the steering tie rod A is connected to the wheel A; the pinion B is connected to the c-end shaft of the commutator B, the pinion B meshes with the rack B, the rack B is connected to the steering tie rod B, and the other end of the steering tie rod B is connected to the wheel B.

[0008] In another implementation of the present invention, the ECU control module automatically implements two steering modes: Mode 1 is when both steering motors are working normally and the electromagnetic clutch is disengaged, i.e., the independent steering mode of each wheel by steer-by-wire; Mode 2 is when one of the two steering motors fails or is ineffective and the electromagnetic clutch is engaged, i.e., the trapezoidal steering mode by steer-by-wire. Mode 1 achieves decoupling of the left and right steering wheels, and Mode 2 serves as a backup for Mode 1 in case of failure.

[0009] In another implementation of the present invention, the ECU control module includes a steering motor fault judgment module, a left and right steering angle calibration module, and a steering angle tracking control module. The steering motor fault judgment module is divided into steering motor A fault judgment and steering motor B fault judgment. It is used to calculate the steering angle tracking error based on the steering angle sensor and the desired steering angle, and compare it with the built-in preset performance function value. If its absolute value is greater than or equal to the function value, it judges the output fault and issues an electromagnetic clutch connection signal, and the dual-mode coupled steer-by-wire enters the mode 2. Otherwise, it judges the output normal and issues an electromagnetic clutch disengagement signal, and the dual-mode coupled steer-by-wire enters the mode 1. The left and right steering angle calibration module is used to judge whether to perform left and right wheel steering angle calibration based on the output result of the steering motor fault judgment module and the steering angle sensor. The steering angle tracking control module is divided into a steering motor A control module and a steering motor B control module. It is used to calculate the output torque of the steering motor based on the obtained steering angle signal and the signal of the left and right steering angle calibration module, and output the steering motor voltage control signal to the steering motor driver A and the steering motor driver B. The steering motor driver A drives the steering motor A, and the steering motor driver B drives the steering motor B.

[0010] In another aspect, the present invention provides a method for controlling the steering angle tracking of a dual-mode coupled steer-by-wire system, comprising: establishing a first steer-by-wire system dynamic model based on parameters obtained from the steering motor A control module when the ECU control module is in mode 1; establishing a second steer-by-wire system dynamic model based on parameters obtained from the steering motor A control module when the ECU control module is in mode 2; establishing a steer-by-wire system state-space model based on the controller structure, the first steer-by-wire system dynamic model, and the second steer-by-wire system dynamic model; and verifying the controller's control effect and optimizing its internal parameters based on the state-space model.

[0011] In another implementation of the present invention, the dynamic model of the first steer-by-wire system is expressed as:

[0012]

[0013] Where, θ fA τ represents the steering angle of the left front wheel, μ represents the equivalent transmission ratio between the steering motor A steering angle and the left front wheel steering angle, and τ represents the steering angle of the left front wheel. mA Given the output torque of steering motor A, the equivalent viscous friction coefficient, equivalent moment of inertia, and uncertain nonlinearity of the steer-by-wire system are expressed as follows:

[0014] B eA1 =B fA +μ 2 B mA +μ 2 BdA

[0015] J eA1 =J fA +μ 2 J mA +μ 2 J dA

[0016] H fA =τ eA +τ fA

[0017] Among them, J fA J mA and J dA The moments of inertia of the left front wheel, steering motor A, and left electromagnetic clutch are respectively, B. fA B mA and B dA τ represents the equivalent viscous friction coefficients of the left front wheel, steering motor A, and left electromagnetic clutch, respectively. eA and τ fA These are the self-aligning torque and friction torque of the left front wheel, respectively.

[0018] In another implementation of the present invention, the dynamic model of the second steer-by-wire system is expressed as follows:

[0019]

[0020] Where, θ f τ represents the steering angle of the front wheel, μ represents the equivalent transmission ratio between the steering motor A steering angle and the left front wheel steering angle, and τ represents the steering angle of the front wheel. mA J is the output torque of steering motor A. eA2 B eA2 and H f Let be the equivalent viscous friction coefficient, equivalent moment of inertia, and uncertain nonlinear quantity of the steer-by-wire system, respectively, expressed as:

[0021] B eA2 =B fA +B fB +μ 2 (B mA +B mB +B d )

[0022] J eA2 =J fA +J fB +μ 2 (J mA +J mB +J d )

[0023] H f =τeA +τ fA +τ eB +τ fB

[0024] Among them, J fA J fB J mA J mB and J d These represent the moments of inertia of the left and right front wheels, steering motors A / B, and the electromagnetic clutch, respectively. fA B fB B mA B mB and B d τ represents the equivalent viscous friction coefficients of the left and right front wheels, steering motors A / B, and the electromagnetic clutch, respectively. eA τ eB τ fA and τ fB These are the self-aligning torque and friction torque of the left and right front wheels, respectively.

[0025] In another aspect, the present invention provides an electronic device, characterized in that it includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the dual-mode coupled steering-by-wire system described above.

[0026] In another aspect, the present invention provides a computer storage medium, characterized in that the computer storage medium stores a computer program, which, when executed by a processor, implements the steps of the dual-mode coupled steer-by-wire system described above.

[0027] In the dual-mode coupled steer-by-wire system of the present invention, two steering motors, steering motor A and steering motor B, are used. When both steering motors are working normally, the electromagnetic clutch is disengaged, that is, mode 1, the two steering wheels steer independently. When one of the steering motors fails or malfunctions, the electromagnetic clutch is engaged, realizing mode 2, trapezoidal steering of the two steering wheels, which effectively improves the steering flexibility and structural reliability of the steer-by-wire system. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. By reading the detailed description of the embodiments below, the advantages and benefits of the solutions will become clear to those skilled in the art. The accompanying drawings are only for illustrating preferred embodiments and are not intended to limit the present invention.

[0029] In the attached diagram:

[0030] Figure 1This is a schematic diagram of the structure of a dual-mode coupled steer-by-wire system according to an embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram of the structure of commutator A and commutator B according to an embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram of the left and right electromagnetic clutches according to an embodiment of the present invention.

[0033] Figure 4 This is a schematic diagram of a low computational complexity preset performance controller structure according to an embodiment of the present invention.

[0034] Figure 5 This is a schematic diagram of the steering angle tracking control process of a dual-mode coupled steer-by-wire system according to an embodiment of the present invention.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1-ECU control module, 2-Steering motor A driver, 3-Steering motor A, 4-Steering motor A reducer, 5-Commutator A, 6-Rack A, 7-Pinus A, 8-Wheel A, 9-Left electromagnetic clutch, 10-Right electromagnetic clutch, 11-Steering motor B driver, 12-Steering motor B, 13-Steering motor B reducer, 14-Commutator B, 15-Rack B, 16-Pinus B, 17-Wheel B, 18-Angle sensor A, 19-Angle sensor B. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and thoroughly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art should fall within the protection scope of the present invention.

[0038] Figure 1 This is a schematic flowchart of a dual-mode coupled steer-by-wire system and its steering angle tracking control method provided by an embodiment of the present invention, as shown below. Figure 1 As shown, this embodiment mainly includes:

[0039] Steering motor module, steering transmission module, commutator, electromagnetic clutch, angle sensor, ECU control module.

[0040] The steering motor module includes a steering motor A driver and a steering motor B driver.

[0041] The commutator includes commutator A and commutator B, which are used to change the direction of the output torque of the steering motor module.

[0042] like Figure 3 As shown, the electromagnetic clutch is used to connect commutator A and commutator B, realizing the disconnection or connection of power between commutator A and commutator B.

[0043] The steering angle sensor is used to obtain the steering angle of the wheel and transmit it to the ECU control module.

[0044] The ECU control module is connected to the angle sensor, the steering motor A driver, and the steering motor B driver, respectively, and is used to control the operation of the electromagnetic clutch, the steering motor A driver, and the steering motor B driver based on the sensing signal from the angle sensor.

[0045] In the dual-mode coupled steer-by-wire system of the present invention, two steering motors, steering motor A and steering motor B, are used. When both steering motors are working normally, the electromagnetic clutch is disengaged, that is, mode 1, the two steering wheels steer independently. When one of the steering motors fails or malfunctions, the electromagnetic clutch is engaged, realizing mode 2, trapezoidal steering of the two steering wheels, which effectively improves the steering flexibility and structural reliability of the steer-by-wire system.

[0046] In another implementation of the present invention, the steering motor module further includes a steering motor A, a steering motor A reducer, a steering motor B, and a steering motor B reducer; as shown Figure 2 As shown, the commutator has three torque input or output terminals, namely terminal a, terminal b, and terminal c; the steering motor A is connected to the a-terminal shaft of the commutator A through the steering motor A reducer, and the b-terminal shaft of the commutator A is connected to the left end of the electromagnetic clutch; the steering motor B is connected to the a-terminal shaft of the commutator B through the steering motor B reducer, and the b-terminal shaft of the commutator B is connected to the right end of the electromagnetic clutch.

[0047] In another embodiment of the present invention, the steering transmission module includes a pinion A, a rack A, a steering tie rod A, a wheel A, a pinion B, a rack B, a steering tie rod B, and a wheel B; the pinion A is connected to the c-end shaft of the commutator A, the pinion A meshes with the rack A, the rack A is connected to the steering tie rod A, and the other end of the steering tie rod A is connected to the wheel A; the pinion B is connected to the c-end shaft of the commutator B, the pinion B meshes with the rack B, the rack B is connected to the steering tie rod B, and the other end of the steering tie rod B is connected to the wheel B.

[0048] In another implementation of the present invention, the ECU control module automatically implements two steering modes: Mode 1 is when both steering motors are working normally and the electromagnetic clutch is disengaged, i.e., the independent steering mode of each wheel of the steer-by-wire system; Mode 2 is when one of the two steering motors fails or is ineffective and the electromagnetic clutch is engaged, i.e., the trapezoidal steering mode of the steer-by-wire system. Mode 1 achieves decoupling of the left and right steering wheels, and Mode 2 serves as a backup for Mode 1 in case of failure, which can improve the reliability of the steer-by-wire system.

[0049] In another implementation of the present invention, the ECU control module includes a steering motor fault judgment module, a left and right steering angle calibration module, and a steering angle tracking control module.

[0050] The steering motor fault diagnosis module is divided into steering motor A fault diagnosis and steering motor B fault diagnosis. It is used to calculate the steering angle tracking error based on the steering angle sensor and the desired steering angle, and compare it with the built-in preset performance function value. If its absolute value is greater than or equal to the function value, it will determine the output fault and issue an electromagnetic clutch connection signal, and the dual-mode coupled steer-by-wire will enter mode 2. Otherwise, it will determine the output is normal and issue an electromagnetic clutch disengagement signal, and the dual-mode coupled steer-by-wire will enter mode 1.

[0051] The left and right steering angle calibration module is used to determine whether to perform steering angle calibration of the left and right wheels based on the output results of the steering motor fault judgment module and the steering angle sensor. The steering angle tracking control module is divided into steering motor A control module and steering motor B control module. It is used to calculate the output torque of the steering motor based on the obtained steering angle signal and the signal from the left and right steering angle calibration module, and output the steering motor voltage control signal to steering motor driver A and steering motor driver B. Steering motor driver A drives steering motor A, and steering motor driver B drives steering motor B.

[0052] In another aspect, the present invention provides a steering angle tracking control method for a dual-mode coupled steer-by-wire system, such as... Figure 5 As shown, it includes:

[0053] When the ECU control module is in mode 1, a dynamic model of the first steer-by-wire system is established based on the parameters obtained by the steering motor A control module.

[0054] When the ECU control module is in mode 2, a dynamic model of the second steer-by-wire system is established based on the parameters obtained from the steering motor A control module.

[0055] Based on the controller structure, the dynamic model of the first steer-by-wire system, and the dynamic model of the second steer-by-wire system, a state-space model of the steer-by-wire system is established.

[0056] Based on the state-space model, the control effect of the controller is verified and its internal parameters are optimized.

[0057] In the dual-mode coupled steer-by-wire system angle tracking control method of the present invention, both steering motor A and steering motor B adopt a low computational complexity preset performance control method. This method has the characteristics of low computational load, thereby reducing the calculation time in the control algorithm and ensuring the timeliness of switching. The difference between the preset performance function and the error can be used as the basis for judging whether to switch. Based on the characteristics of low computational complexity preset performance control, the angle tracking control method of the dual-mode coupled steer-by-wire system is proposed, which effectively enhances the smoothness of angle tracking during mode switching and reduces the computational complexity of control.

[0058] In another implementation of the present invention, the dynamic model of the first steer-by-wire system is expressed as follows:

[0059]

[0060] Where, θ fA τ represents the steering angle of the left front wheel, μ represents the equivalent transmission ratio between the steering motor A steering angle and the left front wheel steering angle, and τ represents the steering angle of the left front wheel. mA Given the output torque of steering motor A, the equivalent viscous friction coefficient, equivalent moment of inertia, and uncertain nonlinearity of the steer-by-wire system are expressed as follows:

[0061] B eA1 =B fA +μ 2 B mA +μ 2 B dA

[0062] J eA1 =J fA +μ 2 J mA +μ 2 J dA

[0063] H fA =τ eA +τ fA

[0064] Among them, J fA J mA and J dA The moments of inertia of the left front wheel, steering motor A, and left electromagnetic clutch are respectively, B. fA B mA and B dA τ represents the equivalent viscous friction coefficients of the left front wheel, steering motor A, and left electromagnetic clutch, respectively. eA and τ fA These are the self-aligning torque and friction torque of the left front wheel, respectively.

[0065] Preferably, as can be seen from the power transmission route, the mechanical structures on the left and right sides are symmetrical in Mode 1. Therefore, the Model 1 dynamic equations of controller A and controller B are equivalent. Taking A (i.e., the left side) as an example, the dynamic equations of Mode 1 are established.

[0066] In another implementation of the present invention, the dynamic model of the second steer-by-wire system is expressed as follows:

[0067]

[0068] Where, θ f τ represents the steering angle of the front wheel, μ represents the equivalent transmission ratio between the steering motor A steering angle and the left front wheel steering angle, and τ represents the steering angle of the front wheel. mA J is the output torque of steering motor A. eA2 B eA2 and H f Let be the equivalent viscous friction coefficient, equivalent moment of inertia, and uncertain nonlinear quantity of the steer-by-wire system, respectively, expressed as:

[0069] B eA2 =B fA +B fB +μ 2 (B mA +B mB +B d )

[0070] J eA2 =J fA +J fB +μ 2 (J mA +J mB +J d )

[0071] H f =τ eA +τ fA +τ eB +τ fB

[0072] Among them, J fA J fB J mA J mB and J d These represent the moments of inertia of the left and right front wheels, steering motors A / B, and the electromagnetic clutch, respectively. fA B fB B mA B mB and B d τ represents the equivalent viscous friction coefficients of the left and right front wheels, steering motors A / B, and the electromagnetic clutch, respectively. eA τ eB τ fA and τfB These are the self-aligning torque and friction torque of the left and right front wheels, respectively.

[0073] Preferably, as can be seen from the power transmission route, after the left and right steering motors fail in mode 2, their transmission power mechanical structure is symmetrical. Therefore, the model 2 dynamic equations of controller A and controller B are equivalent. Taking A (i.e., the left side) as an example, the dynamic equations of mode 2 are established.

[0074] Furthermore, such as Figure 4 As shown, consider the controller structure as follows: The system can then be described as:

[0075]

[0076]

[0077] y = x1

[0078] in, v(u)∈R represents the input of the actuator, y∈R represents the output of the front wheel, both are state vectors, u(t)=τ m It is the control signal of the design, f σi (x,t): R 2 ×R + →R represents the total uncertain nonlinearity, including frictional torque and restoring torque, g σi (t)∈R is an uncertain control coefficient, where σi=1,2 represents mode 1 and mode 2, as detailed below:

[0079]

[0080]

[0081]

[0082]

[0083] In another implementation of the present invention, a control objective is determined for the steer-by-wire system. The transient and steady-state performance of the system is one of the indicators for evaluating the quality of a controller. Therefore, the following control objective is determined: the tracking error range is designed as a function that ensures the system error converges to a steady state within a predetermined time (i.e., transient performance) and guarantees that the system error remains stable within a predetermined range as time approaches infinity (i.e., steady-state performance), specifically as follows:

[0084] -p(t)≤yy d ≤p(t)

[0085] Among them, y dThe desired signal is the desired front wheel steering angle; here we assume y d Both p(t) and its derivative with respect to time are continuous, bounded, and differentiable. p(t) represents the predetermined tracking error range, expressed as:

[0086]

[0087] Where k and ξ are the positive constants to be designed, and tk is the time point at which the specified error is reached.

[0088] In another implementation of the present invention, a design error transformation is performed to achieve the control objective:

[0089] z = λx1 + x2 - λy d

[0090] In another implementation of the invention, the relevant control law is designed as follows:

[0091]

[0092] Where η is the positive constant to be designed, and p is the performance function of the preset performance control.

[0093] In another aspect of the present invention, the electronic device includes: a processor, a memory, and a communication bus and a communication interface.

[0094] in:

[0095] The processor, memory, and communication interface communicate with each other via a communication bus.

[0096] A communication interface is used to communicate with other electronic devices or servers.

[0097] The processor is used to execute programs, specifically the steps of any of the dual-mode coupled steer-by-wire systems described in the above embodiments.

[0098] Specifically, the program may include program code, which includes computer operation instructions.

[0099] The processor may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application. The one or more processors included in the smart device may be processors of the same type, such as one or more CPUs; or they may be processors of different types, such as one or more CPUs and one or more ASICs.

[0100] Memory is used to store programs. Memory may include high-speed RAM, and may also include non-volatile memory, such as at least one disk drive.

[0101] Specifically, the program can be used to cause the processor to execute the steps of any of the dual-mode coupled steer-by-wire systems described in the embodiments. The specific implementation of each step in the program can be found in the corresponding descriptions of the steps and units executed by any of the dual-mode coupled steer-by-wire systems described above, and will not be repeated here. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the devices and modules described above can be referred to the corresponding process descriptions in the foregoing method embodiments.

[0102] An exemplary embodiment of this application also provides a non-transitory computer-readable storage medium storing computer instructions, wherein the computer instructions are used to cause a computer to perform the methods of various embodiments of this application.

[0103] The methods described above according to embodiments of the present invention can be implemented in hardware, firmware, or as software or computer code that can be stored in a recording medium (such as a CD-ROM, RAM, floppy disk, hard disk, or magneto-optical disk), or as computer code originally stored on a remote recording medium or a non-transitory machine-readable medium and subsequently stored on a local recording medium, downloaded via a network. Thus, the methods described herein can be processed by software stored on a recording medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware (such as an ASIC or FPGA). It is understood that the computer, processor, microprocessor controller, or programmable hardware includes storage components (e.g., RAM, ROM, flash memory, etc.) capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods described herein. Furthermore, when a general-purpose computer accesses code used to implement the methods shown herein, the execution of the code transforms the general-purpose computer into a dedicated computer for executing the methods shown herein.

[0104] Specific embodiments of the invention have now been described. Other embodiments are within the scope of the appended claims. In some cases, the actions described in the claims can be performed in a different order and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing can be advantageous.

[0105] It should be noted that all directional indicators (such as up, down, left, right, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0106] In the description of this invention, the terms "first" and "second" are used only for convenience in describing different components or names, and should not be construed as indicating or implying a sequential relationship, relative importance, or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" and "second" may explicitly or implicitly include at least one of that feature.

[0107] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0108] It should be noted that although specific embodiments of the present invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of the present invention. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of the present invention.

[0109] The examples of the embodiments of the present invention are intended to concisely illustrate the technical features of the embodiments of the present invention, so that those skilled in the art can intuitively understand the technical features of the embodiments of the present invention, and are not intended to be an improper limitation of the embodiments of the present invention.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-mode steer-by-wire system, characterized by, include: Steering motor module, steering transmission module, commutator, electromagnetic clutch, angle sensor, ECU control module; The steering motor module includes a steering motor A driver and a steering motor B driver; The commutator includes commutator A and commutator B, which are used to change the direction of the output torque of the steering motor module; The electromagnetic clutch is used to connect the commutator A and the commutator B, so as to realize the disconnection or connection of power between the commutator A and the commutator B. The steering angle sensor is used to obtain the steering angle of the wheel and transmit it to the ECU control module; The ECU control module is connected to the angle sensor, the steering motor A driver and the steering motor B driver respectively, and is used to control the electromagnetic clutch, the steering motor A driver and the steering motor B driver to work according to the sensing signal of the angle sensor; The steering motor module also includes a steering motor A, a steering motor A reducer, a steering motor B, and a steering motor B reducer. The commutator has three torque input or output terminals, namely terminal a, terminal b, and terminal c. The steering motor A is connected to the a-end shaft of the commutator A via the steering motor A reducer, and the b-end shaft of the commutator A is connected to the left end of the electromagnetic clutch. The steering motor B is connected to the a-end shaft of the commutator B via the steering motor B reducer, and the b-end shaft of the commutator B is connected to the right end of the electromagnetic clutch.

2. The system of claim 1, wherein, The steering transmission module includes a pinion A, a rack A, a steering tie rod A, a wheel A, a pinion B, a rack B, a steering tie rod B, and a wheel B; The pinion A is connected to the c-end shaft of the commutator A, the pinion A meshes with the rack A, the rack A is connected to the steering tie rod A, and the other end of the steering tie rod A is connected to the wheel A; The pinion B is connected to the c-end shaft of the commutator B, the pinion B meshes with the rack B, the rack B is connected to the steering tie rod B, and the other end of the steering tie rod B is connected to the wheel B.

3. The system of claim 1, wherein, The ECU control module automatically implements two steering operation modes: Mode 1 is when both steering motors are working normally and the electromagnetic clutch is disengaged, which is the independent steering mode for each wheel of the drive-by-wire system. Mode 2 is for when one of the two steering motors fails or malfunctions, the electromagnetic clutch is engaged, i.e., the steer-by-wire trapezoidal steering mode; In this mode, mode 1 decouples the left and right steering wheels, while mode 2 serves as a backup for mode 1 in case of failure.

4. The system according to claim 3, characterized in that, The ECU control module includes a steering motor fault diagnosis module, a left and right steering angle calibration module, and a steering angle tracking control module; The steering motor fault judgment module is divided into steering motor A fault judgment and steering motor B fault judgment. It is used to calculate the steering angle tracking error based on the steering angle sensor and the desired steering angle, and compare it with the built-in preset performance function value. If its absolute value is greater than or equal to the function value, it judges the output fault and sends an electromagnetic clutch connection signal, and the dual-mode coupled steer-by-wire enters the mode 2. Otherwise, it judges the output normal and sends an electromagnetic clutch disengagement signal, and the dual-mode coupled steer-by-wire enters the mode 1. The left and right steering angle calibration module is used to determine whether to perform steering angle calibration of the left and right wheels based on the output result of the steering motor fault judgment module and the steering angle sensor. The steering angle tracking control module is divided into a steering motor A control module and a steering motor B control module. It is used to calculate the output torque of the steering motor based on the obtained steering angle signal and the left and right steering angle calibration module signal, and output the steering motor voltage control signal to the steering motor driver A and the steering motor driver B. The steering motor driver A drives the steering motor A, and the steering motor driver B drives the steering motor B.

5. A steering angle tracking control method for a dual-mode coupled steer-by-wire system, the method being implemented based on the dual-mode coupled steer-by-wire system as described in any one of claims 1-4, characterized in that, The method includes: When the ECU control module is in mode 1, a first steer-by-wire system dynamic model is established based on the parameters obtained by the steering motor A control module. Mode 1 is when both steering motors are working normally and the electromagnetic clutch is disengaged, i.e., the steer-by-wire system allows each wheel to steer independently. When the ECU control module is in mode 2, a second steer-by-wire system dynamic model is established based on the parameters obtained by the steering motor A control module. Mode 2 is when one of the two steering motors fails or is ineffective, and the electromagnetic clutch is engaged, i.e., the steer-by-wire trapezoidal steering mode. Based on the controller structure, the dynamic model of the first steer-by-wire system and the dynamic model of the second steer-by-wire system, a state-space model of the steer-by-wire system is established. Based on the state-space model, the controller's control effect is verified and its internal parameters are optimized.

6. The method according to claim 5, characterized in that, The dynamic model of the first steer-by-wire system is expressed as follows: in, Indicates the turning angle of the left front wheel. This indicates the equivalent transmission ratio between the steering motor A's rotation angle and the left front wheel's rotation angle. Given the output torque of steering motor A, the equivalent viscous friction coefficient, equivalent moment of inertia, and uncertain nonlinearity of the steer-by-wire system are expressed as follows: in, , and These are the moments of inertia of the left front wheel, steering motor A, and left electromagnetic clutch, respectively. , and These are the equivalent viscous friction coefficients of the left front wheel, steering motor A, and left electromagnetic clutch, respectively. and These are the self-aligning torque and friction torque of the left front wheel, respectively.

7. The method according to claim 5, characterized in that, The dynamic model of the second steer-by-wire system is expressed as follows: in, Indicates the steering angle of the front wheels. This indicates the equivalent transmission ratio between the steering motor A's rotation angle and the left front wheel's rotation angle. The output torque of steering motor A, , and Let be the equivalent viscous friction coefficient, equivalent moment of inertia, and uncertain nonlinear quantity of the steer-by-wire system, respectively, expressed as: in, , , , and These are the moments of inertia of the left and right front wheels, steering motors A / B, and the electromagnetic clutch, respectively. , , , and These are the equivalent viscous friction coefficients for the left and right front wheels, steering motors A / B, and the electromagnetic clutch, respectively. , , and These are the self-aligning torque and friction torque of the left and right front wheels, respectively.

8. An electronic device, characterized in that, include: The system includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of the dual-mode coupled steering-by-wire system angle tracking control method as described in any one of claims 5-7.

9. A computer storage medium, characterized in that, The computer storage medium stores a computer program, which, when executed by a processor, implements the steps in the dual-mode coupled steer-by-wire system angle tracking control method as described in any one of claims 5-7.

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