CN118254875B - A kind of steering-by-wire system and steering control method thereof - Google Patents

Abstract

The present invention relates to the technical field of electric vehicles, and in particular to a wire-controlled steering system and a steering control method thereof. The solution of the present application outputs a target steering angle to a main controller and a backup controller. When the vehicle is driving normally, the main controller performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the real-time steering angle detected by the output detection device. When a fault in the output detection device is detected, the main controller stops the steering closed-loop control, and the backup controller simulates the real-time steering angle of the steering mechanism according to the target steering angle, and then performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the simulated real-time steering angle. The present application uses a backup controller for steering closed-loop control redundancy. When the steering closed loop of the main controller fails, the backup controller provides safety protection to the steering mechanism, thereby effectively improving the safety of the entire system.

Description

A steer-by-wire system and a steering control method thereof

Technical Field

The present invention relates to the technical field of electric vehicles, and in particular to a wire-controlled steering system and a steering control method thereof.

Background technique

The steer-by-wire system is a major branch product of the steer-by-wire chassis system and an important component of the chassis execution end of smart driving vehicles. The steer-by-wire system mainly realizes precise control of the vehicle's steering angle according to the position control instructions of the vehicle's decision-making layer. Since the steering angle instructions of the smart driving system change in real time, under different road conditions, the steering actuator must be able to act quickly and accurately according to the vehicle's position control instructions.

In the prior art, in order to avoid the loss of safety performance caused by the lack of mechanical connection between the wire-controlled steering system and the driver's control, a safety fault-tolerant design is generally added to provide a backup steering function to ensure the safety of the system at the system level. In the current related technology, safety redundancy is generally performed for the ECU (vehicle control system) and the motor, while the output detection device of the steering execution module is difficult to perform physical or other forms of redundancy due to the harsh installation environment and size limitations. Therefore, the safety redundancy of the feedback input of the execution module is not considered.

Summary of the invention

A steer-by-wire system and a steering control method thereof provided in an embodiment of the present application solve the problem that the existing steer-by-wire system cannot provide safety redundancy for the output detection device in the steering execution module.

According to a first aspect, an embodiment provides a steering control method of a steer-by-wire system, the steer-by-wire system comprising a steering wheel module, a main controller, a backup controller and an output detection device, the output detection device being used to detect a real-time steering angle of a steering mechanism, the steering control method comprising:

The steering wheel module receives a steering instruction issued by a user, obtains a target steering angle according to the steering instruction, and outputs the target steering angle to the main controller and the standby controller;

The main controller performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the real-time steering angle detected by the output detection device;

Detecting whether the output detection device fails;

When the output detection device fails, the main controller stops the steering closed-loop control of the steering mechanism, and the standby controller simulates the real-time steering angle of the steering mechanism according to the target steering angle, and performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the simulated real-time steering angle; or,

When the output detection device fails, the backup controller simulates the real-time steering angle of the steering mechanism according to the target steering angle, and the main controller performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the simulated real-time steering angle.

In an achievable implementation, the standby controller simulates a real-time steering angle of the steering mechanism according to the target steering angle, including:

The backup controller inputs the target steering angle into a preset system model of the steering mechanism to obtain a simulated real-time steering angle output by the system model; wherein the system model includes: a functional relationship reflecting the functional relationship between the target steering angle and the simulated real-time steering angle.

In an achievable implementation, the functional relationship has a key parameter matrix, and the key parameter matrix affects the functional relationship between the target steering angle and the simulated real-time steering angle; the method further includes:

Obtaining the real-time steering angle fed back by the output detection device;

Determine whether the difference between the simulated real-time steering angle and the real-time steering angle exceeds a preset threshold value. If so, adjust the key parameter matrix according to the size and direction of the difference, so that the adjusted key parameter matrix is used in the next loop instruction to adjust the system model until the difference does not exceed the preset threshold value; otherwise, continue to use the current key parameter matrix to adjust the system model in the next loop instruction.

In one practicable implementation, the initial key parameter matrix is obtained in the following manner:

The external thrust device sequentially pushes the steering mechanism to steer according to a plurality of different target steering angles; the output detection device detects the real-time steering angle of the steering mechanism at different target steering angles;

Curve fitting is performed on each target steering angle and the corresponding detected real-time steering angle to obtain a key parameter matrix.

In an achievable implementation, the fitting formula for performing curve fitting on each target steering angle and the corresponding detected real-time steering angle is expressed as:

;

In the formula, represents the key parameter matrix, represents the weight corresponding to the i -th target steering angle, i represents the i -th target steering angle, n represents the number of set target steering angles, Indicates the actual output value of the vehicle turning angle, Represents the system model simulation output value.

In an achievable implementation, an adjustment coefficient is correspondingly set for different vehicle speeds, and before determining whether the difference between the simulated real-time steering angle and the real-time steering angle exceeds a preset threshold, the method further includes:

Determine the corresponding adjustment coefficient according to the current speed of the vehicle;

The key parameter matrix is adjusted according to the adjustment coefficient.

In an achievable implementation, adjusting the key parameter matrix according to the size and direction of the difference includes:

When the difference in the next cycle instruction is greater than the difference in the previous cycle instruction, adjusting the key parameter matrix according to the ratio of the increase of the difference, so that the adjustment amplitude of the simulated real-time steering angle approaching the real-time steering angle increases;

When the difference in the next cycle instruction is less than the difference in the previous cycle instruction, the key parameter matrix is adjusted according to the ratio of the difference reduction, so that the adjustment amplitude of the simulated real-time steering angle approaching the real-time steering angle is reduced.

In an achievable implementation manner, after adjusting the key parameter matrix according to the size and direction of the difference, the method further includes:

The adjusted key parameter matrix is written into a read-only memory, and the adjusted key parameter matrix overwrites the key parameter matrix written last time.

In an achievable implementation manner, the detecting whether the output detection device fails includes:

The range and validity of the real-time steering angle are obtained, and whether the output detection device fails is determined based on the range and validity of the real-time steering angle.

In an achievable implementation, detecting that the output detection device has no faults further includes:

Sending the real-time steering angle signal output by the output detection device to the standby controller in real time;

Proofreading the real-time steering angle signal with the simulated real-time steering angle to obtain a proofreading result;

The key parameter matrix is adjusted in real time according to the proofreading result.

According to a second aspect, an embodiment provides a steer-by-wire system, comprising a steering wheel module, a main controller, a backup controller and an output detection device, wherein the output detection device is used to detect a real-time steering angle of a steering mechanism;

The steering wheel module receives a steering instruction issued by a user, obtains a target steering angle according to the steering instruction, and outputs the target steering angle to the main controller and the standby controller;

The main controller performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the real-time steering angle detected by the output detection device;

The steer-by-wire system further comprises:

A detection module, used to detect whether the output detection device fails;

When the output detection device fails, the main controller stops the steering closed-loop control of the steering mechanism, and the standby controller simulates the real-time steering angle of the steering mechanism according to the target steering angle, and performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the simulated real-time steering angle; or,

When the output detection device fails, the backup controller simulates the real-time steering angle of the steering mechanism according to the target steering angle, and the main controller performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the simulated real-time steering angle.

According to a third aspect, a computer-readable storage medium is provided, wherein a program is stored on the medium, and wherein the program can be executed by a processor to implement the steering control method of the steer-by-wire system as described above.

According to the above-mentioned embodiment of the steer-by-wire system and its steering control method, the received steering command is converted into a target steering angle and then output to the main controller and the backup controller. When the vehicle is driving normally, the main controller performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the real-time steering angle detected by the output detection device. When a fault in the output detection device is detected, the main controller stops the steering closed-loop control, and the backup controller simulates the real-time steering angle of the steering mechanism according to the target steering angle, and then performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the simulated real-time steering angle. Through the above-mentioned scheme of the present application, a backup controller is used for steering closed-loop control redundancy. When the steering closed loop of the main controller fails, the backup controller provides safety protection for the steering mechanism. Without increasing any cost and size of the output detection device, the safety of the entire system can still be effectively improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of a steering control method of a steer-by-wire system according to the present embodiment;

FIG2 is a second flow chart of the steering control method of the steer-by-wire system of the present embodiment;

FIG3 is a third flow chart of the steering control method of the steer-by-wire system of the present embodiment;

FIG4 is a flow chart of the output detection device of this embodiment when no failure occurs;

FIG5 is a structural block diagram of the steer-by-wire system of this embodiment;

FIG6 is a first schematic diagram of a steer-by-wire system according to the present embodiment;

FIG. 7 is a second principle block diagram of the steer-by-wire system of this embodiment.

Figure numerals: 10, steering wheel module; 20, main controller; 30, backup controller; 40, control execution module; 50, output detection device; 60, detection module.

Detailed ways

The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

For the existing wire-controlled steering system, since there is no mechanical connection between the steering wheel end and the steering execution end, it is equivalent to the steering wheel end providing the steering command, and the steering execution end executing the command and providing feedback on the execution effect. However, the steering execution end itself does not have a device for detecting output feedback, so it is necessary to increase the output detection of the steering execution end to ensure that the feedback on the execution effect is correct. At present, in order to ensure the control safety after the cancellation of the mechanical and the functional safety requirements of the wire-controlled steering system for intelligent driving, the wire-controlled steering system will put forward very high requirements on the redundancy of the system. The existing system redundancy methods are generally concentrated on the motor, controller or steering wheel module's angle torque sensor, and the output detection device of the steering execution module is difficult to be physically or other forms of redundancy due to the harsh installation environment and size limitations. On the basis of not adding other equipment, the present application provides a backup control algorithm for the wire-controlled steering system to achieve the steering closed-loop control that the steering execution module can still complete after the output detection device fails.

As shown in FIG1 , the present embodiment provides a steering control method for a wire-controlled steering system, wherein the wire-controlled steering system includes a steering wheel module, a main controller, a backup controller, and an output detection device, wherein the output detection device is used to detect the real-time steering angle of the steering mechanism. Specifically, both the main controller and the backup controller belong to the steering execution module. When the output detection device is normal, the main controller is used to execute the main control algorithm and output it to the steering execution motor in the form of a control signal to control the steering execution motor to achieve steering. At the same time, the output detection device is used to detect the real-time steering angle of the steering mechanism (such as the steering execution motor, or the steering mechanical structure of the vehicle driven by the motor), and feed back the detection result to the main controller. The main controller adjusts the control signal according to the feedback result, and then sends the adjusted control signal to the steering execution motor to achieve steering calibration, so as to achieve steering closed-loop control. Among them, the real-time steering angle of the steering mechanism can be the angle of the steering mechanical structure or the angle of the motor.

Specifically, the steering control method includes the following steps:

Step 100: The steering wheel module receives a steering instruction issued by a user, obtains a target steering angle according to the steering instruction, and outputs the target steering angle to the main controller and the backup controller.

First, after receiving the steering instruction given by the user, the steering wheel module simply processes the steering instruction and outputs it as a target steering angle, and outputs the target steering angle to the main controller and the backup controller respectively.

Step 200: The main controller performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the real-time steering angle detected by the output detection device.

Then, the main controller executes the main control algorithm and controls the steering actuator motor according to the target steering angle. At the same time, the output detection device feeds back the detected real-time steering angle to the main controller to achieve closed-loop control of the steering mechanism.

Step 300: Detect whether the output detection device fails.

At the same time, the output detection device is detected by the detection module. Specifically, the detection module detects the sensor signal output by the output detection device, wherein the output detection device can be a gear angle sensor, a rack position sensor or a torque sensor, and the corresponding output detection device is set according to different steering mechanical structures. When the output detection device is a gear angle sensor, the detection module detects the gear angle signal; when the output detection device is a rack position sensor, the detection module detects the rack displacement signal; when the output detection device is a torque sensor, the detection module detects the torque signal. Specifically, it is judged whether the output detection device is faulty according to the range and validity of the real-time steering angle, that is, it is judged whether the output detection device is faulty by detecting the range and validity of the signal output by the output detection device. For example, under normal circumstances, the output signal defaults to 0. When it is judged that the output signal of the output detection device is 1, it is determined that the output detection device is faulty, and then it is decided to enable the backup control method.

Step 400: When the output detection device fails, the main controller stops the closed-loop control of the steering mechanism, and the backup controller simulates the real-time steering angle of the steering mechanism according to the target steering angle, and performs closed-loop control of the steering of the steering mechanism according to the target steering angle and the simulated real-time steering angle.

When a fault is detected in the output detection device, the main controller stops the steering closed-loop control of the steering mechanism. At this time, the backup controller is used to execute the backup control algorithm. The backup control algorithm models the entire steering execution module, and the key parameter matrix obtained by reverse deduction through the previous calibration test is used to ensure the accuracy and stability of the model, and the sensorless closed-loop control of the steering execution module of the wire control steering system is performed based on the real-time simulation output of the model. Specifically, in conjunction with Figure 6, in the backup controller, after the output detection closed-loop control module receives the target steering angle signal, it simulates the system model to obtain a simulated output signal (simulated real-time steering angle), and then feeds the simulated output signal back to the output detection closed-loop control module. The output detection closed-loop control module adjusts the feedback signal according to the target steering angle to form a backup control instruction, and sends the backup control instruction to the main controller. The main controller controls the steering mechanism (that is, the control execution module) to steer according to the backup control instruction, thereby realizing the steering closed-loop control.

It should be noted that the output detection closed-loop control module in this embodiment has the same function as the main controller in the normal state, and both can be used to receive the control instruction of the vehicle turning angle and perform real-time closed-loop control based on the feedback output. The difference is that the software module in the standby controller receives the simulated output signal obtained by system model simulation, while the main controller directly receives the real output signal of the output detection device in the normal state.

As a further improvement of this embodiment, referring to Figure 2, after step 300, when a fault is detected in the output detection device, step 400 can also be replaced by step 500: the backup controller simulates the real-time steering angle of the steering mechanism according to the target steering angle, and the main controller performs closed-loop control of the steering of the steering mechanism according to the target steering angle and the simulated real-time steering angle.

Specifically, after the backup controller receives the target steering angle, the system model is simulated to obtain a simulated output signal (simulated real-time steering angle), and then the simulated output signal is fed back to the main controller. The main controller adjusts the control signal according to the feedback result, and then sends the adjusted control signal to the steering actuator motor to achieve steering closed-loop control.

By adopting the steering control method of the embodiment of the present application, a backup controller is used for steering closed-loop control redundancy. When a steering closed loop of the main controller fails, the backup controller is used to provide safety protection for the steering mechanism. Without increasing any cost and size of the output detection device, the safety of the entire system can still be effectively improved.

In this embodiment, the backup controller simulates the real-time steering angle of the steering mechanism according to the target steering angle, specifically including: the backup controller inputs the target steering angle into a preset system model of the steering mechanism, and obtains the simulated real-time steering angle output by the system model; wherein the system model includes: a functional relationship reflecting the functional relationship between the target steering angle and the simulated real-time steering angle.

In actual application, the motor and mechanical structure (reduction mechanism) will be analyzed in advance before being put into use, and the basic system model corresponding to the steering execution module will be established. The system model is used to express the functional relationship between the vehicle angle and the motor output angle. After being put into use, the target steering angle is input into the system model, and the simulated real-time steering angle (i.e., vehicle angle) will be output.

As a further improvement of this embodiment, specifically, the functional relationship has a key parameter matrix, and the key parameter matrix affects the functional relationship between the target steering angle and the simulated real-time steering angle. In this embodiment, the output of the system model is adjusted by the key parameter matrix [ Kn ] so that the simulated output result (simulated real-time steering angle) can be as close as possible _to the real result (target steering angle), so as to achieve closed-loop control of the output.

As shown in FIG3 , the steering control method further includes the following steps:

Step 600: Obtain the real-time steering angle fed back by the output detection device.

Step 700: Determine whether the difference between the simulated real-time steering angle and the real-time steering angle fed back by the output detection device exceeds a preset threshold value. If so, execute step 800: adjust the key parameter matrix according to the size and direction of the difference, so that the adjusted key parameter matrix is used in the next loop instruction to adjust the system model until the difference does not exceed the preset threshold value; otherwise, execute step 900: continue to use the current key parameter matrix to adjust the system model in the next loop instruction.

In the actual application of this embodiment, the key parameter matrix needs to be adjusted. Specifically, by comparing the simulated real-time steering angle output by the standby controller with the real-time steering angle fed back by the output detection device, it is determined whether the error between the simulated real-time steering angle and the real-time steering angle exceeds the preset threshold. When the error exceeds the preset threshold, the key parameter matrix [ Kn ] is adjusted in the next loop instruction according to the numerical value and _direction of the error, and the adjusted key parameter matrix is used in the next loop instruction to adjust the system model until the error is guaranteed to be within the preset threshold. When the error does not exceed the preset threshold, it is considered that the error is controllable, that is, the simulation is effective, then the current key parameter matrix is continued to be used to adjust the system model in the next loop instruction.

When in use, there will be an initial key parameter matrix in the system model, and specifically, the initial key parameter matrix is obtained in the following way:

The external thrust device pushes the steering mechanism to turn according to multiple different target steering angles; the output detection device detects the real-time steering angle of the steering mechanism under different target steering angles. Then, curve fitting is performed on each target steering angle and the corresponding detected real-time steering angle to obtain the key parameter matrix.

The steering execution module has different mechanical structures and corresponding output detection device types. The initial value of the key parameter matrix [ Kn _] is obtained by calibrating the steering execution module on the test bench structure. The actual steering output under different steering commands is measured to obtain the output curve. The output curve is then fitted with the simulation output of the corresponding system model to obtain [ Kn _] .

Specifically, the fitting formula for curve fitting of each target steering angle and the corresponding detected real-time steering angle is expressed as:

;

In the formula, represents the key parameter matrix, represents the weight corresponding to the i -th target steering angle, i represents the i -th target steering angle, n represents the number of set target steering angles, Indicates the actual output value of the vehicle turning angle, Represents the system model simulation output value.

This embodiment is described by taking the mechanical mechanism of the steering execution module as a gear rack mechanical structure as an example, and the detection type of the output detection device is rack displacement. The target steering angle is characterized by the rack displacement.

The steering execution module of the corresponding system model is placed on a special test bench. The full stroke X of the rack is set by an external thrust device without using a motor. X is divided into several sections (8 sections in this embodiment). The real output rack displacement y _r is measured and recorded in sequence according to the test sequence of ±[0, 1/8X, 2/8X, 3/8X, 4/8X, 5/8X, 6/8X, 7/8X, X]. In addition, according to the mechanical corresponding formula between the vehicle front wheel angle and the output gear angle of the steering execution module, the simulated rack displacement output data y _i under ±[0, 1/8X, 2/8X, 3/8X, 4/8X, 5/8X, 6/8X, 7/8X, X] is obtained.

Among them, Wi ( n ) is based on the accuracy requirements of the data points corresponding to the target steering angle, mainly to assign a higher weight to the 8 data points _close to the center position, because the control accuracy requirements at the center position will be higher. The local weighting method is set because the system model based on the key parameters may not be close to the actual output when outputting, so it is necessary to control [ Kn ] in real time with the assistance of the motor angle to ensure that the control of the cumulative error between the system model output and the actual output is within an acceptable range. More specifically, Wi ( n ) is set according to the distance of the rack travel point, such as the initial setting of [ _0.5 , 0.5, 0.6, 0.6, _{0.8, 0.8, 0.8, 1, 0.8, 0.8, 0.8, 0.6, 0.6, 0.5, 0.5]. The initial key parameter matrix [Kn] is calculated based on the rack displacement yr output of the first two steps, the simulated rack displacement output data yi and the} corresponding _weight Wi ( n ₎ .

By obtaining [ Kn ] _, we can get the corresponding function formula of the system model of this application:

;

In the formula, is the vehicle turning angle, is the motor steering angle, is the final output of steering actuators with different mechanical structures (i.e., the functional relationship between vehicle steering angle and motor steering angle).

Among them, the motor steering angle can be directly obtained through measurement, and then the motor steering angle, the key parameter matrix and the final output of the steering actuator of the mechanical structure are respectively substituted into the above formula to obtain the vehicle angle (i.e., the simulated real-time steering angle).

As a further improvement of this embodiment, an adjustment coefficient is set correspondingly under different vehicle speeds. Before judging whether the difference between the simulated real-time steering angle and the real-time steering angle fed back by the output detection device exceeds a preset threshold, it also includes: determining the corresponding adjustment coefficient according to the current speed of the vehicle; and then adjusting the key parameter matrix according to the adjustment coefficient.

Specifically, in actual applications, the key parameter matrix [ Kn _] is also affected by the vehicle speed. There will be an adjustment coefficient α (where α is the parameter name, indicating the gain coefficient) at different vehicle speeds, so that different key parameter matrices [ Kn ] are obtained at different vehicle speeds. Therefore, dynamic changes are required during control _, so _it will _become αKn during actual execution. Specifically, α =1+ K0 *Vehspd, where K0 is an adjustment parameter, which can be adjusted _in real time according to the driver's needs; Vehspd represents the vehicle speed signal, and the unit is Km/h kilometers per hour.

Therefore, further, based on the corresponding function formula of the above system model, the corresponding function formula after _adding the key parameter matrix [ Kn ] based on the influence of the steering module speed becomes:

.

In this embodiment, the adjustment of the key parameter matrix, that is, adjusting the key parameter matrix according to the size and direction of the difference, specifically includes:

When the difference in the next cycle instruction is greater than the difference in the previous cycle instruction, the key parameter matrix is adjusted according to the ratio of the increase in the difference, so that the adjustment range of the simulated real-time steering angle closer to the real-time steering angle is increased.

When the difference in the next cycle instruction is less than the difference in the previous cycle instruction, the key parameter matrix is adjusted according to the ratio of the difference reduction, so that the adjustment amplitude of the simulated real-time steering angle close to the real-time steering angle is reduced.

It should be noted that, in this embodiment, the adjustment of the key parameter matrix is achieved when the output detection device is in normal operation, by comparing the real-time steering angle fed back by the output detection device with the real-time steering angle simulated by the standby controller.

Specifically, the following is an example of adjusting the key parameter matrix:

Obtain the difference between the real-time steering angle signal fed back by the output detection device received under the current cycle instruction and the real-time steering angle simulated by the standby controller (recorded as the first difference), and the difference between the real-time steering angle signal fed back by the output detection device received under the next cycle instruction and the real-time steering angle simulated by the standby controller (recorded as the second difference). At this time, the first difference and the second difference both exceed the preset threshold value, compare the first difference and the second difference, when the second difference is greater than the first difference, it means that the error between the real-time steering angle fed back by the output detection device and the real-time steering angle simulated by the standby controller is increasing, and at this time it is necessary to increase [ Kn ], which is achieved by multiplying [ Kn ] by _a coefficient (greater than 1). When the second difference is less _than the first difference, it means that the error between the real-time steering angle fed back by the output detection device and the real-time steering angle simulated by the standby controller is decreasing, _and at this time it is necessary to reduce [ Kn ], which is achieved by multiplying [ Kn _] by a coefficient (less than 1). By periodically adjusting [ Kn _] , the simulated real-time steering angle can be infinitely close to the real steering angle, so that the backup controller can provide backup control instructions in real time for the main controller to provide control instruction redundancy, thereby ensuring that at the moment when the output detection device fails, the backup controller can immediately feedback with a signal close to the real output.

As a further improvement of the present method embodiment, after adjusting the key parameter matrix according to the size and direction of the difference, it also includes: writing the adjusted key parameter matrix into a read-only memory, and making the adjusted key parameter matrix overwrite the key parameter matrix written last time.

As shown in _Figures 6 and 7, after receiving the request that the key parameter matrix needs to be changed, the data change module writes the key parameter matrix [ Kn ] into the ROM (read-only memory) through assembly language, so that the next control is directly executed according to the latest key parameter matrix [ Kn _] .

In this embodiment, as shown in FIG. 4 , when it is detected that the output detection device has no fault, that is, the steer-by-wire system is operating normally, the steering control method further includes the following steps:

Step 310: Send the real-time steering angle signal output by the output detection device to the standby controller in real time.

Step 320: calibrate the real-time steering angle signal with the simulated real-time steering angle to obtain a calibration result.

Step 330: Adjust the key parameter matrix in real time according to the proofreading results.

Specifically, when the output detection device is operating normally, taking the rack position sensor as an example, the backup control algorithm monitors the signal value state of the rack position sensor in real time (i.e., the signal range and signal validity), and makes a difference between the rack position signal and the simulated rack position signal, and dynamically adjusts [ Kn ] according to the difference, wherein the specific dynamic adjustment method refers to the adjustment of the key parameter matrix in the above embodiment. At the same time, the backup control algorithm also provides backup control instructions for the main control algorithm to make control instruction redundancy, so as to ensure _that the output detection device can be fed back immediately with a signal close to the real output at the moment of failure.

Referring to Figure 5, this embodiment provides a wire-controlled steering system, including a steering wheel module 10, a main controller 20, a backup controller 30 and an output detection device 50, the output detection device 50 is used to detect the real-time steering angle of the steering mechanism; the steering wheel module 10 receives a steering instruction issued by a user, obtains a target steering angle according to the steering instruction and outputs it to the main controller 20 and the backup controller 30; the main controller 20 performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the real-time steering angle detected by the output detection device 50.

The wire control steering system also includes a detection module 60 and a control execution module 40. The detection module 60 is used to detect whether the output detection device 50 fails; when the output detection device 50 fails, the main controller 20 stops the steering closed-loop control of the steering mechanism, and the backup controller 30 simulates the real-time steering angle of the steering mechanism according to the target steering angle, and performs closed-loop control on the steering of the steering mechanism (i.e., the control execution module 40) according to the target steering angle and the simulated real-time steering angle; or, when the output detection device 50 fails, the backup controller 30 simulates the real-time steering angle of the steering mechanism according to the target steering angle, and the main controller 20 performs closed-loop control on the steering of the steering mechanism (i.e., the control execution module 40) according to the target steering angle and the simulated real-time steering angle.

In the wire-controlled steering system of the present embodiment, the functions and effects performed by the steering wheel module 10, the main controller 20, the backup controller 30, the output detection device 50, the detection module 60 and the control execution module 40 have been described in detail in the above-mentioned steering control method embodiment, and will not be elaborated in detail in the present embodiment.

This embodiment provides a computer-readable storage medium, on which a program is stored, and the program can be executed by a processor to implement the steering control method of the wire steering system as described in the above embodiment. Since the steering control method of the wire steering system has been described in detail in the above embodiment, this embodiment will not be repeated in detail here.

Those skilled in the art will appreciate that all or part of the functions of the various methods in the above-mentioned embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above-mentioned embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, and the storage medium can include: a read-only memory, a random access memory, a disk, an optical disk, a hard disk, etc., and the program is executed by a computer to implement the above-mentioned functions. For example, the program is stored in the memory of the device, and when the program in the memory is executed by the processor, all or part of the above-mentioned functions can be implemented. In addition, when all or part of the functions in the above-mentioned embodiments are implemented by computer programs, the program can also be stored in a storage medium such as a server, another computer, a disk, an optical disk, a flash disk or a mobile hard disk, and can be downloaded or copied and saved in the memory of the local device, or the system of the local device is updated, and when the program in the memory is executed by the processor, all or part of the functions in the above-mentioned embodiments can be implemented.

The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the idea of the present invention, some simple deductions, modifications or substitutions can be made.

Claims (8)

1. A steering control method of a steer-by-wire system, the steer-by-wire system including a steering wheel module, a main controller, a standby controller, and an output detection device for detecting a real-time steering angle of a steering mechanism, the steering control method comprising:

The steering wheel module receives a steering instruction sent by a user, obtains a target steering angle according to the steering instruction and outputs the target steering angle to the main controller and the standby controller;

The main controller performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the real-time steering angle detected by the output detection device;

detecting whether the output detection device has a fault;

when the output detection device fails, the main controller stops steering closed-loop control of the steering mechanism, the standby controller simulates a real-time steering angle of the steering mechanism according to the target steering angle, and the steering of the steering mechanism is closed-loop controlled according to the target steering angle and the simulated real-time steering angle; or alternatively

When the output detection device fails, the standby controller simulates a real-time steering angle of the steering mechanism according to the target steering angle, and the main controller performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the simulated real-time steering angle;

The standby controller simulates a real-time steering angle of the steering mechanism according to the target steering angle, and comprises the following steps: the standby controller inputs the target steering angle into a system model of a preset steering mechanism to obtain a simulated real-time steering angle output by the system model; wherein, the system model includes: a functional relation reflecting a functional relation between the target steering angle and the simulated real-time steering angle;

The functional relation is provided with a key parameter matrix, and the key parameter matrix influences the functional relation between the target steering angle and the simulated real-time steering angle; the method further comprises the steps of:

Acquiring a real-time steering angle fed back by the output detection device;

Judging whether the difference value between the simulated real-time steering angle and the real-time steering angle exceeds a preset threshold value, if so, adjusting the key parameter matrix according to the magnitude and the direction of the difference value, so that the system model is adjusted by adopting the adjusted key parameter matrix in the next circulation instruction until the difference value does not exceed the preset threshold value; otherwise, continuing to adopt the current key parameter matrix to adjust the system model in the next circulation instruction.

2. The steering control method of claim 1, wherein the initial key parameter matrix is obtained by:

the external thrust device sequentially pushes the steering mechanism to steer according to a plurality of different target steering angles; the output detection device detects real-time steering angles of the steering mechanism under different target steering angles;

and performing curve fitting on each target steering angle and the corresponding detected real-time steering angle to obtain a key parameter matrix.

3. The steering control method according to claim 2, wherein the fitting formula for curve-fitting each target steering angle and the corresponding detected real-time steering angle is expressed as:

；

Wherein [ K _n ] represents a key parameter matrix, W _i (n) represents a weight corresponding to an ith target steering angle, i represents the ith target steering angle, n represents the number of set target steering angles, y _r represents an actual output value of a vehicle corner, and y _i represents a system model simulation output value.

4. The steering control method according to claim 1, wherein adjustment coefficients are correspondingly provided for different vehicle speeds, and the determining whether the difference between the simulated real-time steering angle and the real-time steering angle exceeds a preset threshold value is preceded by:

determining a corresponding adjustment coefficient according to the current speed of the vehicle;

and adjusting the key parameter matrix according to the adjustment coefficient.

5. The steering control method according to claim 1, wherein said adjusting the key parameter matrix according to the magnitude and direction of the difference value comprises:

when the difference value in the next circulation instruction is larger than the difference value in the previous circulation instruction, the key parameter matrix is adjusted according to the proportion of the increase of the difference value, so that the adjustment amplitude of the simulated real-time steering angle approaching the real-time steering angle is increased;

And when the difference value in the next circulation instruction is smaller than the difference value in the previous circulation instruction, adjusting the key parameter matrix according to the proportion of the decrease of the difference value, so that the adjustment amplitude of the simulated real-time steering angle approaching the real-time steering angle is reduced.

6. The steering control method according to claim 4, wherein after said adjusting the key parameter matrix according to the magnitude and direction of the difference value, further comprising:

writing the adjusted key parameter matrix into a read-only memory, and enabling the adjusted key parameter matrix to cover the key parameter matrix written last time.

7. The steering control method according to claim 1, characterized in that detecting that the output detection device has not failed, further comprises:

the real-time steering angle signal output by the output detection device is sent to the standby controller in real time;

The real-time steering angle signal is checked with the real-time steering angle simulated by the vehicle to obtain a check result;

and regulating and controlling the key parameter matrix in real time according to the correction result.

8. The steering-by-wire system is characterized by comprising a steering wheel module, a main controller, a standby controller and an output detection device, wherein the output detection device is used for detecting the real-time steering angle of a steering mechanism;

The steering wheel module receives a steering instruction sent by a user, obtains a target steering angle according to the steering instruction and outputs the target steering angle to the main controller and the standby controller;

The main controller performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the real-time steering angle detected by the output detection device;

The steer-by-wire system further includes:

the detection module is used for detecting whether the output detection device has faults or not;

when the output detection device fails, the main controller stops steering closed-loop control of the steering mechanism, the standby controller simulates a real-time steering angle of the steering mechanism according to the target steering angle, and the steering of the steering mechanism is closed-loop controlled according to the target steering angle and the simulated real-time steering angle; or alternatively

When the output detection device fails, the standby controller simulates a real-time steering angle of the steering mechanism according to the target steering angle, and the main controller performs closed-loop control on the steering of the steering mechanism according to the target steering angle and the simulated real-time steering angle;

The standby controller simulates a real-time steering angle of the steering mechanism according to the target steering angle, and comprises the following steps: the standby controller inputs the target steering angle into a system model of a preset steering mechanism to obtain a simulated real-time steering angle output by the system model; wherein, the system model includes: a functional relation reflecting a functional relation between the target steering angle and the simulated real-time steering angle;

The functional relation is provided with a key parameter matrix, and the key parameter matrix influences the functional relation between the target steering angle and the simulated real-time steering angle; the system further comprises:

Acquiring a real-time steering angle fed back by the output detection device;

Judging whether the difference value between the simulated real-time steering angle and the real-time steering angle exceeds a preset threshold value, if so, adjusting the key parameter matrix according to the magnitude and the direction of the difference value, so that the system model is adjusted by adopting the adjusted key parameter matrix in the next circulation instruction until the difference value does not exceed the preset threshold value; otherwise, continuing to adopt the current key parameter matrix to adjust the system model in the next circulation instruction.