Control method and device of steer-by-wire system, electronic equipment and storage medium

Abstract

The invention relates to a control method and device of a steer-by-wire system, electronic equipment and a storage medium. The control method of the steer-by-wire system comprises the steps that basic feedback torque and road feeling feedback torque are determined according to driving control state data of a vehicle and steering related data of the steer-by-wire system; determining output proportion coefficients corresponding to the basic feedback torque and the road feeling feedback torque according to the driving control state data; and based on the basic feedback torque, the road feeling feedback torque, and the output ratio coefficients corresponding to the basic feedback torque and the road feeling feedback torque, determining a target feedback torque of the up-rotating motor. According to the embodiment of the invention, different output proportion coefficients can be distributed according to the driving control state data as the basic feedback torque and the road feeling feedback torque, and the target feedback torque of the upward-rotating motor is obtained through superposition output, so that a driver can obtain a good steering hand feeling similar to that of a traditional EPS, the vehicle can be flexibly controlled to steer, and the steering efficiency is improved. The change of an actual road surface can be sensed, the risk is pre-judged in advance, and the driving safety is improved.

Description

Technical Field

[0001] This application relates to the field of steer-by-wire systems, and more particularly to a control method, apparatus, electronic device, and storage medium for a steer-by-wire system. Background Technology

[0002] With the continuous development of the automotive industry, consumers' demands for vehicle driving performance and ease of use are constantly increasing. In order to meet the needs of increasingly intelligent and functional vehicles, steering systems have also undergone multiple generations of iteration, from the initial mechanical steering, hydraulic steering, and electric power steering, to today's steer-by-wire systems.

[0003] The steer-by-wire system comprises an upward-turning feel simulation mechanism and a downward-turning front-wheel drive mechanism. By eliminating the mechanical connection, it decouples the steering wheel from the steering wheels, providing significant flexibility in the layout and design of the steering control system and facilitating integration with the entire vehicle system. Furthermore, the steer-by-wire system offers high control precision and fast response, enabling easier integration and data sharing with other automotive subsystems. This significantly improves vehicle handling stability and safety, facilitating more advanced intelligent driving.

[0004] However, due to the decoupling of the upper and lower parts of the steer-by-wire system, the actual friction force of the traditional tires, after being transmitted to the lower rack (usually represented by rack force), cannot be transmitted to the steering wheel through the mechanical intermediate shaft. Therefore, the steering feel control scheme of the traditional electric power steering system is no longer suitable for the upper steering feel simulation mechanism of the steer-by-wire system. It needs to be redesigned according to the characteristics of the steer-by-wire system. Some existing steer-by-wire feel simulation technologies focus on mode scene switching, while others focus on the design of redundant schemes. There is a lack of research on the overall system solution for improving the steering feel simulation effect. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems, this application provides a control method, device, electronic device and storage medium for a steer-by-wire system.

[0006] In a first aspect, this application provides a control method for a steer-by-wire system, including: Acquire vehicle driving control status data and steering-related data of the steer-by-wire system; The basic feedback torque and road feel feedback torque are determined based on the steering-related data and the driving control status data; The output proportion coefficients corresponding to the basic feedback torque and road feel feedback torque are determined based on the driving control state data. The target feedback torque of the steering motor is determined based on the basic feedback torque, the road feel feedback torque, the basic feedback torque, and the output ratio coefficient corresponding to the road feel feedback torque, and the steering motor of the steer-by-wire system is controlled to output the target feedback torque.

[0007] Optionally, the steering-related data includes: downward turning angle, steering wheel angle, and steering wheel speed; the driving control status data includes: vehicle speed and driving mode information. The basic feedback torque is determined based on the steering-related data and the driving control state data, including: Calculate the comfort rack force based on the downturn angle and the vehicle speed; The basic feedback torque is calculated based on the comfort rack force, the downturn angle, the steering wheel angle, the steering wheel speed, the vehicle speed, and the driving mode information.

[0008] Optionally, calculating the comfort rack force based on the downturn angle and the vehicle speed includes: Obtain the front wheel steering angle corresponding to the downturn angle; The lateral force of the entire vehicle is determined based on the front wheel steering angle and the vehicle speed. The original value of the comfort rack force is determined based on the lateral force of the entire vehicle. The rack force coefficient is determined based on the downward rotation angle and the vehicle speed. Calculate the product of the original value of the comfort rack force and the rack force coefficient; The product is low-pass filtered to obtain the comfort rack force.

[0009] Optionally, the basic feedback torque is calculated based on the comfort rack force, the downward steering angle, the steering wheel angle, the steering wheel rotation speed, the vehicle speed, and the driving mode information, including: The initial value of the basic feedback torque is determined based on the comfort rack force, the vehicle speed, and the driving mode information. The damping coefficient is determined based on the vehicle speed and the steering wheel rotation speed; The following feedback coefficient is determined based on the difference between the steering wheel angle and the downward steering angle; The basic feedback torque is obtained by calculating the product of the initial value of the basic feedback torque, the damping coefficient, and the following feedback coefficient.

[0010] Optionally, the following feedback coefficient is determined based on the difference between the steering wheel angle and the downturn angle, including: Determine whether the difference is within a preset deviation range; If the difference is within the preset deviation range, the follow-up feedback coefficient will be set to 1; If the difference is outside the preset deviation range, the follow-up feedback coefficient is determined according to the preset natural logarithm and exponential composite function.

[0011] Optionally, the steering-related data includes: the speed of the lower steering motor, the torque of the lower steering motor, the steering wheel speed, and the actual hand torque; the driving control status data includes: vehicle speed and driving mode information. Determining the road feel feedback torque based on the steering-related data and the driving control state data includes: The dynamic rack force is determined based on the speed and torque of the lower motor. The desired hand torque is determined based on the dynamic rack force, vehicle speed, and driving mode information. The road feel feedback torque is determined based on the desired hand torque, the steering wheel speed, and the actual hand torque.

[0012] Optionally, determining the dynamic rack force based on the speed and torque of the lower motor includes: The speed and torque of the lower motor are input into the dynamic mechanical model of the steer-by-wire system to obtain the original value of the dynamic rack force. The original value of the dynamic rack force is processed by dead zone processing to obtain the dynamic rack force.

[0013] Optionally, determining the road feel feedback torque based on the desired hand torque, the steering wheel rotation speed, and the actual hand torque includes: Calculate the torque difference between the actual hand torque and the desired hand torque; The integral coefficient is determined based on the steering wheel rotation speed; The torque difference is subjected to PID closed-loop control based on the integral coefficient to obtain the road feel feedback torque.

[0014] Optionally, determining the integral coefficient based on the steering wheel rotation speed includes: Determine whether the steering wheel rotation speed is greater than the upper threshold; If the steering wheel rotation speed is greater than the upper threshold, the integral coefficient is determined to be 1; If the steering wheel speed is less than or equal to the upper threshold, determine whether the steering wheel speed is less than the lower threshold. If the steering wheel rotation speed is less than the lower threshold, the integral coefficient is determined to be 0; If the steering wheel rotation speed is greater than or equal to the lower threshold, the integral coefficient is calculated based on the steering wheel rotation speed, the upper threshold, and the lower threshold.

[0015] Optionally, the driving control status data includes: vehicle speed and road sense switching coefficient; Based on the driving control state data, the output proportion coefficients corresponding to the basic feedback torque and road feel feedback torque are determined, including: Obtain the feedforward value of the target feedback torque from the previous moment; The original weighting coefficients for road feel feedback are determined based on the vehicle speed and the feedforward value. The product of the original weighting coefficient of the road feedback and the road switching coefficient is calculated to obtain the road feedback torque weighting coefficient, which is used as the output proportion coefficient corresponding to the road feedback torque. Calculate the difference between 1 and the road feel feedback torque weighting coefficient to obtain the basic feedback torque weighting coefficient, which is used as the output proportion coefficient corresponding to the basic feedback torque.

[0016] Optionally, determining the target feedback torque of the steering motor based on the basic feedback torque, the road feel feedback torque, the basic feedback torque, and the output proportion coefficient corresponding to the road feel feedback torque, and controlling the steering motor of the steer-by-wire system to output the target feedback torque, includes: The product of the road feedback torque and the output proportion coefficient corresponding to the road feedback torque is calculated to obtain the road feedback torque component; The basic feedback torque component is obtained by multiplying the basic feedback torque by the output proportion coefficient corresponding to the basic feedback torque. The target feedback torque is obtained by summing the road feel feedback torque component and the basic feedback torque component and then limiting the sum. The target feedback torque is output by the upper motor of the steering-by-wire system.

[0017] Secondly, this application provides a control device for a steer-by-wire system, comprising: The acquisition module is used to acquire vehicle driving control status data and steering-related data of the steer-by-wire system; The first determining module is used to determine the basic feedback torque and road feel feedback torque based on the steering-related data and the driving control state data; The second determining module is used to determine the output proportion coefficients corresponding to the basic feedback torque and the road feel feedback torque based on the driving control state data. The third determining module is used to determine the target feedback torque of the upper steering motor based on the basic feedback torque, the road feel feedback torque, the basic feedback torque and the output proportion coefficient corresponding to the road feel feedback torque, and control the upper steering motor of the steer-by-wire system to output the target feedback torque.

[0018] Thirdly, this application provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; The processor, when executing a program stored in memory, implements the control method of the steer-by-wire system described in any of the first aspects.

[0019] Fourthly, this application provides a computer-readable storage medium storing a program for a control method of a steer-by-wire system, wherein when the program for the control method of the steer-by-wire system is executed by a processor, it implements the steps of the control method of the steer-by-wire system according to any one of the first aspects.

[0020] The beneficial effects of this invention are: This application embodiment determines the basic feedback torque and road feel feedback torque based on the vehicle's steering-related data and driving control status data. Then, it allocates different output ratio coefficients to the basic feedback torque and road feel feedback torque based on the driving control status data. After superimposing the outputs, the target feedback torque of the upper motor is obtained, which allows the driver to obtain a good steering feel similar to that of a traditional EPS. This allows the driver to flexibly control the vehicle's steering, perceive changes in the actual road surface, anticipate risks in advance, and improve driving safety. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A flowchart illustrating a control method for a steer-by-wire system provided in this application embodiment; Figure 2 A logic block diagram of a control method for a steer-by-wire system provided in an embodiment of this application; Figure 3 for Figure 1 A flowchart of step S102; Figure 4 A logic block diagram for calculating the basic feedback torque is provided in an embodiment of this application; Figure 5 for Figure 1 Another flowchart for step S102; Figure 6 A logic block diagram for calculating road feel feedback torque provided in an embodiment of this application; Figure 7 A logic block diagram for calculating the target feedback torque is provided in an embodiment of this application; Figure 8 A structural diagram of a control device for a steer-by-wire system provided in an embodiment of this application; Figure 9 This is a structural diagram of an electronic device provided in an embodiment of this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] Due to the decoupling of the upper and lower parts of the steer-by-wire system, the actual friction force of the traditional tires, after being transmitted to the lower rack (usually represented by rack force), cannot be transmitted to the steering wheel through the mechanical intermediate shaft. Therefore, the steering feel control scheme of the traditional electric power steering system is no longer suitable for the upper steering feel simulation mechanism of the steer-by-wire system. It needs to be redesigned according to the characteristics of the steer-by-wire system. However, some existing steer-by-wire feel simulation technologies focus on mode scene switching, while others focus on the design of redundant schemes. There is a lack of research on the overall system solution for improving the steering feel simulation effect.

[0026] Therefore, this application provides a control method, device, electronic device, and storage medium for a steer-by-wire system. The feedback torque of the upper steering motor used for feel simulation is calculated by arbitrarily mixing a basic feedback torque and a road feel feedback torque using a specific strategy. The basic feedback torque is mainly calculated with reference to the vehicle's running posture, providing the driver with a basic feel for hand operation, facilitating control of the vehicle's running posture. The road feel feedback torque is mainly calculated by referencing the actual operating parameters of the lower steering motor through closed-loop control with the steering torque. It is more sensitive and can realistically reflect the actual road conditions, providing the driver with clearer road feel feedback. Finally, the basic feedback torque and road feel feedback torque are allocated different output ratio coefficients according to vehicle speed and the strength of the actual requested torque under different conditions. This allows the driver to obtain a good steering feel similar to traditional EPS, enabling flexible control of the vehicle's steering, perception of changes in the actual road surface, early risk prediction, and improved driving safety.

[0027] This application provides a control method for a steer-by-wire system, such as... Figure 1 As shown, it includes: Step S101: Obtain vehicle driving control status data and steering-related data of the steer-by-wire system; In this embodiment, driving control status data refers to data reflecting the vehicle's driving and handling status, including: vehicle speed, driving mode information, and road feel switch coefficient. The vehicle speed can be detected by the vehicle speed sensor; the driving mode information refers to information about the driving mode set by the user. For example, the driving modes include: Sport mode and Comfort mode; the road feel switch coefficient can be set by the user through the central control screen, and its value ranges from 0 to 1. When set to 0, the road feel torque is completely turned off, and the final output only has the basic feedback torque component; when set to 1, the road feel feedback torque component is kept normally open; when set to a value between 0 and 1, the strength of the road feel feedback can be adjusted.

[0028] Steering-related data for a steer-by-wire system refers to its core parameters, which determine the system's steering accuracy, response speed, and driving feel. These data include: steering angle, steering wheel angle, steering wheel speed, steering motor speed, steering motor torque, and actual hand torque (i.e., actual steering wheel hand torque). Specifically, the steering angle refers to the actual angle by which the front wheels (or steering wheels) turn left or right from the "straight-line driving position," which can be detected by a steering gear angle sensor. The steering wheel angle refers to the angle by which the steering wheel turns left or right from the "centering position," which can be detected by a steering wheel angle sensor. The steering wheel speed refers to the number of revolutions the steering wheel makes per unit time. The rate of change of the steering angle can be obtained by "differential calculation" of the signal from the steering wheel angle sensor. The speed of the steering motor refers to the rotational speed of the motor that drives the steering mechanism in the vehicle's electric power steering system (EPS) or steer-by-wire system, which can be obtained by the number of rotations of the motor rotor per unit time. The torque of the steering motor refers to the "rotational torque" output by the steering motor, which can be obtained by "current calculation" of the motor controller or directly detected by the torque sensor. The actual hand torque refers to the reaction torque of the steering wheel on the hands that the driver actually feels when turning the steering wheel, which can be directly detected by the "torque sensor" installed between the steering column and the steering gear.

[0029] Step S102: Determine the basic feedback torque and road feel feedback torque based on the steering-related data and the driving control state data; In this embodiment, the basic feedback torque is calculated based on the steering wheel angle, downturn angle, steering wheel speed, vehicle speed, and the comfort rack force obtained from steering-related data and driving control status data. Since it mainly references steering-related data and driving control status data, the basic feedback torque can more realistically reflect the steer-by-wire and vehicle driving control status, providing the driver with basic hand force operation feedback.

[0030] like Figure 2 As shown, the comfort rack force can be calculated first based on the down-turn angle in the steering-related data and the vehicle speed in the driving control status data. Then, the basic feedback torque can be calculated based on the comfort rack force, the steering wheel angle, down-turn angle, and steering wheel speed in the steering-related data, and the vehicle speed in the driving control status data. The road feel feedback torque is obtained by first calculating the dynamic rack force from the down-turn motor operating parameters and the vehicle speed (vehicle speed in the figure) to obtain the target hand steering wheel torque. This torque is then obtained through closed-loop calculation with the actual hand steering wheel force. The output of the integral part is controlled based on the integral coefficient calculated by the speed to avoid torque step problems.

[0031] Since the road feel feedback torque is mainly calculated based on the dynamic model of the lower actuator and the motor operating parameters, and the motor rotor of the lower actuator is relatively sensitive, the road feel feedback torque is relatively sensitive and can truly reflect the actual road conditions, giving the driver a clearer road feel feedback.

[0032] Specifically, in one embodiment of this application, such as Figure 3 As shown, step S102 determines the basic feedback torque based on the steering-related data and the driving control state data, including: Step S201: Calculate the comfort rack force based on the downturn angle and the vehicle speed; In this step, the front wheel angle corresponding to the downturn angle can be obtained; the lateral force of the whole vehicle can be determined based on the front wheel angle and the vehicle speed; the original value of the comfort rack force can be determined based on the lateral force of the whole vehicle; the rack force coefficient can be determined based on the downturn angle and the vehicle speed; the product of the original value of the comfort rack force and the rack force coefficient can be calculated; and the product can be low-pass filtered to obtain the comfort rack force.

[0033] In this embodiment, the correspondence between the downturn angle and the front wheel angle can be preset. The corresponding front wheel angle can be found in the correspondence based on the downturn angle in the steering-related data. The found front wheel angle is multiplied by a preset coefficient (determined according to vehicle dynamics parameters) to obtain the front wheel angle corresponding to the downturn angle in the steering-related data.

[0034] After obtaining the front wheel steering angle, the lateral force of the entire vehicle can be calculated using the following formula: F_y= m*a y =m*[V 2 *δ / (L+K*V 2 )] Where F_y is the lateral force, m is the total vehicle mass, and a y V is the lateral acceleration, L is the vehicle speed, δ is the vehicle wheelbase, δ is the front wheel steering angle, and K is the stability factor, which is a constant parameter.

[0035] After calculating the lateral force of the entire vehicle, the original value of the comfort rack force can be calculated using the following rack force calculation formula: F_rack = (F_y *r_gear) / (i_sw×η) Where F_rack is the original value of the comfort rack force, F_y is the lateral force, r_gear is the pitch circle radius of the gear (m), i_sw is the steering ratio, and η is the mechanical efficiency.

[0036] The rack force coefficient can be calculated using a bilinear interpolation lookup table based on the downturn angle and vehicle speed. In the corresponding lookup table data, this coefficient exhibits the following pattern: it increases with the increase of the downturn angle; when the downturn angle is small, if the vehicle speed decreases simultaneously, the coefficient will further decrease. For example, the numerical range of the rack force coefficient is 0.8-1.5. The function of the rack force coefficient is to increase the comfortable rack force output at large angles and high speeds.

[0037] The original value of the comfort rack force is multiplied by the comfort rack force coefficient, and then a first-order low-pass filter is applied to obtain the required comfort rack force. The purpose of the first-order low-pass filter is to filter out the high-frequency jitter and focus more on the output of comfort.

[0038] Step S202: Calculate the basic feedback torque based on the comfort rack force, the downward turning angle, the steering wheel angle, the steering wheel speed, the vehicle speed, and the driving mode information.

[0039] In this step, such as Figure 4 As shown, the initial value of the basic feedback torque can be determined based on the comfort rack force, the vehicle speed, and the driving mode information; the damping coefficient can be determined based on the vehicle speed and the steering wheel speed; the following feedback coefficient can be determined based on the difference between the steering wheel angle and the downturn angle; and the product of the initial value of the basic feedback torque, the damping coefficient, and the following feedback coefficient can be calculated to obtain the basic feedback torque.

[0040] In this embodiment, different initial values ​​for the basic feedback torque can be pre-set according to the driving mode. In Sport mode, the user expects a greater steering effort, while in Comfort mode, the user expects a smaller effort. Therefore, the initial values ​​for the basic feedback torque in the table are generally set higher in Sport mode and lower in Comfort mode. This initial value table is a two-dimensional table; the rows represent torque values ​​based on the comfort rack force breakpoint, and the columns represent torque values ​​based on the vehicle speed breakpoint. The initial values ​​of the basic feedback torque increase with both the comfort rack force and vehicle speed.

[0041] Based on the table of initial values ​​of basic feedback torque, the initial value of basic feedback torque can be calculated by looking up the table using bilinear difference between the comfort rack force and the vehicle speed.

[0042] In this embodiment, the relationship between vehicle speed, steering wheel rotation speed, and damping coefficient can be preset, with the damping coefficient increasing as vehicle speed and steering wheel rotation speed increase. Based on this relationship, the damping coefficient is calculated to provide stronger hand force feedback during rapid steering and at high speeds, thereby increasing steering stability.

[0043] When calculating the follow feedback coefficient, the difference between the steering wheel angle and the downturn angle can be calculated first to obtain the angle deviation. If the angle deviation is within the preset deviation range (calibrable value), the follow feedback coefficient is 1. If the angle deviation is outside the preset deviation range, the follow feedback coefficient can be obtained by using the calculation method of natural logarithm and exponential composite function, so that the follow coefficient increases linearly when the angle deviation is small, and the feedback torque is rapidly increased to slow down the speed when the angle difference is too large, so as to avoid instability.

[0044] The formulas for the composite function of the natural logarithm and the exponential function are as follows:

[0045] in, k1 is the angle deviation (unit: degrees), taken as the absolute value to ensure symmetry; k2 is the overall gain coefficient, k1>0, used to adjust the feedback strength; k3 is the logarithmic sensitivity parameter, k2>0, used to control the smoothness of the small angle region; k4 is the exponential growth parameter, k3>0, used to dominate the rapid enhancement of the large angle region (usually k3∈(0.05, 0.2)).

[0046] Therefore, in the small angular deviation region Natural logarithm dominant: (Taylor expansion linear approximation); the exponent term is approximately 1: The function simplifies to: It exhibits linear growth, avoiding high-frequency oscillations; in the large-angle deviation region... The index component dominates growth: Follow ( Exponential growth; logarithmic growth: To prevent excessive and rapid increases; compound effects: This enables rapid enhanced feedback and accelerates system convergence.

[0047] The basic feedback torque can be directly obtained by multiplying the initial value of the basic feedback torque by the damping coefficient and then by the following feedback coefficient. Alternatively, the amplitude of the output value can be limited, with the limit decreasing as the vehicle speed increases to ensure safety. Specifically, the basic feedback torque can be obtained by applying a lookup table to the torque based on the vehicle speed. The lookup table limit can refer to the motor parameters to limit the vehicle speed. For example, if the maximum output of the motor is 8 Nm, then the low-speed limit is 8 Nm and the high-speed limit is 6 Nm.

[0048] In this embodiment, the calculation of the basic feedback torque takes into account enhanced hand force feedback during high-speed and rapid steering to improve driving stability, and incorporates follow-up feedback for downward steering, making it easier for the driver to perceive the actual response state of the vehicle. Furthermore, the basic feedback torque also considers enhancing torque feedback through damping coefficients in rapid steering and high-speed driving scenarios, and when downward steering fails to follow upward steering in time, using a nonlinear follow-up feedback coefficient to rapidly increase the feedback torque and reduce steering wheel speed to prevent instability when the angle deviation is too large.

[0049] The basic feedback torque obtained by the above method can also be superimposed (summed) with the active self-centering torque, the end-of-pipe protection torque, or the torque requested by the driver assistance system. Specifically, the self-centering torque can be superimposed during self-centering, the end-of-pipe protection torque can be superimposed when entering the end-of-pipe state, and the requested torque can be superimposed when ADAS requests torque. See the appendix for details. Figure 4 The dashed part in the text.

[0050] In one embodiment of this application, such as Figure 5 As shown, step S102 determines the road feel feedback torque based on the steering-related data and the driving control state data, including: Step S301: Determine the dynamic rack force based on the speed and torque of the lower motor; In this step, the speed and torque of the lower-rotor motor can be input into the dynamic mechanical model of the steer-by-wire system to obtain the original value of the dynamic rack force; the original value of the dynamic rack force is then processed to obtain the dynamic rack force.

[0051] The dynamic mechanics model takes into account the combined effects of friction and inertia in the steering system, and its formula is as follows:

[0052] in, This represents the original value of the dynamic rack force. The transmission ratio for converting the torque of the lower-rotor motor into dynamic rack force. For rotational inertia, For the motor rotation angle, This represents the second derivative with respect to the motor rotation angle, which indicates the motor's angular acceleration. For frictional torque, This refers to the motor torque.

[0053] Dead zone is when the output torque is 0 when the engine speed is below a speed threshold, preventing frequent changes. The speed threshold dynamically changes based on vehicle speed, increasing with speed. By processing the raw dynamic rack force value with dead zone control, the influence of the dead zone position on the output dynamic rack force is eliminated. Introducing dead zone control prevents the output dynamic rack force from being overly sensitive, resulting in a more realistic road feel feedback torque.

[0054] Step S302: Determine the desired hand torque based on the dynamic rack force, vehicle speed, and driving mode information; The desired hand torque of the drive-by-wire system is the desired hand feedback torque, which is theoretically proportional to the downward rotation rack force. That is, the greater the rack force, the greater the desired hand feedback torque should be. However, the hand feedback torque is obtained through the reaction force of the upward rotation motor. Therefore, a target hand torque is calculated first, and then the actual required motor torque is calculated in the subsequent road feel feedback torque module.

[0055] Specifically, the desired hand torque can be calculated by looking up a table using the bilinear difference between the dynamic rack force and the vehicle speed. The desired hand torque can be set with different calibration parameters according to the input driving mode (e.g., the driving mode is Sport or Comfort, the steering hand force is heavier in Sport mode and the desired hand force is smaller in Comfort mode, so the desired hand torque value can be calibrated by adjusting the value of the desired hand torque according to the driving mode) to obtain target hand torque of different intensities.

[0056] Step S303: Determine the road feel feedback torque based on the desired hand torque, the steering wheel speed, and the actual hand torque.

[0057] In this step, the torque difference between the actual hand torque and the desired hand torque can be calculated; the integral coefficient can be determined based on the steering wheel speed; and PID closed-loop control can be performed on the torque difference based on the integral coefficient to obtain the road feel feedback torque.

[0058] In practical applications, such as Figure 6 As shown, the required road feel feedback torque (i.e. motor torque) can be calculated by PID closed-loop control based on the difference between the actual hand torque and the desired steering wheel hand torque (i.e., the desired hand torque).

[0059] Determining the integral coefficient based on the steering wheel rotation speed includes: determining whether the steering wheel rotation speed is greater than an upper threshold; if the steering wheel rotation speed is greater than the upper threshold, determining the integral coefficient to be 1; if the steering wheel rotation speed is less than or equal to the upper threshold, determining whether the steering wheel rotation speed is less than a lower threshold; if the steering wheel rotation speed is less than the lower threshold, determining the integral coefficient to be 0; if the steering wheel rotation speed is greater than or equal to the lower threshold, calculating the integral coefficient based on the steering wheel rotation speed, the upper threshold, and the lower threshold. Specifically, the integral coefficient = (steering wheel rotation speed - lower threshold) * 1 / (upper threshold - lower threshold).

[0060] In other words, the coefficient is set to 1 when the steering wheel speed is greater than the upper threshold (an empirically set calibration value, ranging from 5-10° / s, with an example upper threshold of 8° / s), and set to 0 when it is less than the lower threshold (an empirically set calibration value, ranging from 0-3° / s, with an example lower threshold of 1° / s). When the steering wheel speed is between these two thresholds, the integral coefficient = (steering wheel speed - 1) * 1 / (8 - 1). Therefore, the integral coefficient can change linearly with the increase or decrease of the steering wheel speed, decreasing linearly from 1 to 0, or increasing linearly from 0 to 1, to ensure a smooth steering feel during slow turns and to avoid excessive sensitivity in the integral accumulation during low-speed steering. The integral coefficient is multiplied after the integral accumulator in the PID control to control the magnitude of the entire integral part.

[0061] The steering wheel speed is used to reduce the integral coefficient through the integral coefficient calculation unit when the steering wheel speed is low (specifically, the lower the speed, the smaller the integral coefficient; when the speed is less than the lower threshold, the integral coefficient is reduced to 0, i.e., the integral is cleared to zero). Based on the integral coefficient, the output of the integral part is reduced in the PID calculation unit. The road feel feedback torque part uses the PID closed-loop method to provide more accurate torque feedback. Unlike the open-loop control of comfort torque, the integral coefficient avoids torque step caused by integral saturation when finely adjusting the steering wheel at low speed, thereby avoiding excessive fluctuations in the output road feel feedback torque.

[0062] Step S103: Determine the output ratio coefficients corresponding to the basic feedback torque and road feel feedback torque based on the driving control state data; In this step, different output proportion coefficients can be assigned to the basic feedback torque and the road feel feedback torque based on the driving control status data, so as to obtain the output proportion coefficient of the basic feedback torque and the output proportion coefficient corresponding to the road feel feedback torque.

[0063] In one embodiment of this application, step S103, which determines the road feel feedback torque of the upper motor based on the driving control state data, the basic feedback torque, and the road feel feedback torque, includes: obtaining the feedforward value of the target feedback torque at the previous moment; determining the original weight coefficient of the road feel feedback based on the vehicle speed and the feedforward value; calculating the product of the original weight coefficient of the road feel feedback and the road feel switching coefficient to obtain the road feel feedback torque weight coefficient, which is used as the output proportion coefficient corresponding to the road feel feedback torque; and calculating the difference between I and the road feel feedback torque weight coefficient to obtain the basic feedback torque weight coefficient, which is used as the output proportion coefficient corresponding to the basic feedback torque.

[0064] In practical applications, such as Figure 7 As shown, the feedback torque can be determined based on the vehicle speed and the target ( Figure 7 The feedforward value (representing the final feedback torque) is used to obtain the original weighting coefficient B for road feel feedback from Table 1 via a bilinear lookup table method. The original weighting coefficient B has the following characteristics: its value ranges from 0 to 1, and it decreases as vehicle speed increases, with a larger weighting value at low vehicle speeds and a smaller weighting value at high vehicle speeds. The table used to obtain the original weighting coefficient B for road feel feedback is shown in Table 1 below. In Table 1, "rows" represent torque breakpoints, and "columns" represent vehicle speed breakpoints. Specific parameters are obtained based on vehicle model tuning.

[0065] Table 1

[0066] The road feedback original weight coefficient B is multiplied by the road feedback switching coefficient A to obtain the road feedback torque weight coefficient C. The basic feedback torque weight coefficient is 1-C, where B represents the proportion of the road feedback torque in the target feedback torque by default. Multiplying the original road feedback weight coefficient B by the road feedback switching coefficient A means further reducing the proportion of the road feedback torque in the target feedback torque by the road feedback switching coefficient A, so as to reduce the proportion of the road feedback torque in the target feedback torque.

[0067] For example, if the initial weighting coefficient B for road feedback is 0.5, it means that by default, the proportion of road feedback torque to the target feedback torque at a certain vehicle speed is 0.5. If the road feedback switching coefficient A is 0.4, then B*A=0.2, which means reducing the proportion of road feedback torque in the target feedback torque to 0.2. If the road feedback switching coefficient A is set to 0, it means that the proportion of road feedback torque in the target feedback torque is 0, that is, it does not include road feedback torque. If the road feedback switching coefficient A is set to 1, it means that the proportion of road feedback torque in the target feedback torque is the default factory setting proportion.

[0068] Step S104: Determine the target feedback torque of the upper steering motor based on the basic feedback torque, the road feel feedback torque, the basic feedback torque, and the output ratio coefficient corresponding to the road feel feedback torque, and control the upper steering motor of the steer-by-wire system to output the target feedback torque.

[0069] In one embodiment of this application, step S104 determines the target feedback torque of the steering motor based on the basic feedback torque, the road feel feedback torque, the basic feedback torque, and the output proportion coefficient corresponding to the road feel feedback torque, and controls the steering motor of the steer-by-wire system to output the target feedback torque, including: calculating the product of the road feel feedback torque and the output proportion coefficient corresponding to the road feel feedback torque to obtain a road feel feedback torque component; calculating the product of the basic feedback torque and the output proportion coefficient corresponding to the basic feedback torque to obtain a basic feedback torque component; summing the road feel feedback torque component and the basic feedback torque component, limiting the sum to obtain the target feedback torque, and controlling the steering motor of the steer-by-wire system to output the target feedback torque.

[0070] Since the preceding text uses the road feel feedback torque weighting coefficient as the output proportion coefficient corresponding to the road feel feedback torque, and the basic feedback torque weighting coefficient as the output proportion coefficient corresponding to the basic feedback torque, as follows: Figure 7 As shown, the road feedback torque component is obtained by multiplying the road feedback torque by the road feedback torque weighting coefficient C, and the basic feedback torque component is obtained by multiplying the basic feedback torque by (1-C). The road feedback torque component and the basic feedback torque component are then superimposed, and after passing through the torque slope change limit and upper and lower amplitude limits, the final feedback torque is obtained. Specifically, the torque slope change limit and upper and lower amplitude limits refer to the following: when the output torque change rate is greater than the slope change limit, the torque change is performed according to the maximum limit of the slope change rate; when the output torque value exceeds the torque amplitude limit, the maximum limit is applied.

[0071] The above design allows for the distribution of more road feedback torque components when the vehicle is traveling at low speeds and with high torque, making it easier for the driver to perceive the specific road surface conditions. At high speeds, less road feedback torque components are distributed, resulting in a smoother ride and easier control of the vehicle's driving posture.

[0072] Personalized customization can be achieved by controlling the road feel switching coefficient. This control coefficient can indirectly control the proportion of the road feel feedback torque in the target feedback torque, so that the road feel strength can be adjusted. Different driving settings can be achieved according to the driving preferences of different drivers to meet diverse driving needs.

[0073] This embodiment first calculates the comfort rack force and dynamic rack force simultaneously based on the output signal and vehicle parameters. Then, it calculates the basic feedback torque based on the comfort rack force and the target hand torque and road feel feedback torque based on the dynamic rack force. Finally, the basic feedback torque and road feel feedback torque are arbitrated according to vehicle speed and torque magnitude before being output: at low vehicle speeds and high torques, the road feel feedback torque accounts for a larger proportion, emphasizing road feel; at high vehicle speeds and low torques, the basic feedback torque accounts for a larger proportion, emphasizing comfort. Next, it determines whether the external road feel switch coefficient A is not 1. Based on the road feel switch coefficient A, it either disables the road feel or adjusts the strength of the road feel feedback to achieve personalized adjustment. This allows for different driving settings based on different drivers' driving preferences, meeting diverse driving needs.

[0074] This application embodiment determines the basic feedback torque and road feel feedback torque based on the vehicle's steering-related data and driving control status data. Then, it allocates different output ratio coefficients to the basic feedback torque and road feel feedback torque based on the driving control status data. After superimposing the outputs, the target feedback torque of the upper motor is obtained, which allows the driver to obtain a good steering feel similar to that of a traditional EPS. This allows the driver to flexibly control the vehicle's steering, perceive changes in the actual road surface, anticipate risks in advance, and improve driving safety.

[0075] In another embodiment of this application, a control device for a steer-by-wire system is also provided, such as... Figure 8 As shown, it includes: The acquisition module 11 is used to acquire vehicle driving control status data and steering-related data of the steer-by-wire system; The first determining module 12 is used to determine the basic feedback torque and the road feel feedback torque based on the steering-related data and the driving control state data; The second determining module 13 is used to determine the output ratio coefficients corresponding to the basic feedback torque and the road feel feedback torque based on the driving control state data. The third determining module 14 is used to determine the target feedback torque of the upper steering motor based on the basic feedback torque, the road feel feedback torque, the basic feedback torque and the output ratio coefficient corresponding to the road feel feedback torque, and to control the upper steering motor of the steer-by-wire system to output the target feedback torque.

[0076] In another embodiment of this application, an electronic device is also provided, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus. Memory, used to store computer programs; The processor, when executing a program stored in memory, implements the control method of the steer-by-wire system described in any of the foregoing method embodiments.

[0077] The electronic device provided in this embodiment of the invention has a processor that executes a program stored in a memory to determine the basic feedback torque and road feel feedback torque based on the vehicle's steering-related data and driving control status data. Then, based on the driving control status data, it allocates different output ratio coefficients to the basic feedback torque and road feel feedback torque, and after superimposing the outputs, it obtains the target feedback torque of the upper motor. This allows the driver to obtain a good steering feel similar to that of a traditional EPS, enabling flexible control of the vehicle's steering, perception of changes in the actual road surface, and advance prediction of risks, thereby improving driving safety.

[0078] The communication bus 1140 mentioned in the above-mentioned electronic device can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus 1140 can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 9 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0079] The communication interface 1120 is used for communication between the above-mentioned electronic device and other devices.

[0080] The memory 1130 may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0081] The processor 1110 mentioned above can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0082] In another embodiment of this application, a computer-readable storage medium is provided, on which a program for a control method of a steer-by-wire system is stored. When the program for the control method of the steer-by-wire system is executed by a processor, it implements the steps of the control method of the steer-by-wire system described in any of the foregoing method embodiments.

[0083] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0084] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A control method for a steer-by-wire system, characterized in that, include: Acquire vehicle driving control status data and steering-related data of the steer-by-wire system; The basic feedback torque and road feel feedback torque are determined based on the steering-related data and the driving control status data; The output proportion coefficients corresponding to the basic feedback torque and road feel feedback torque are determined based on the driving control state data. The driving control status data includes: vehicle speed and road sense switching coefficient; Based on the driving control state data, the output proportion coefficients corresponding to the basic feedback torque and road feel feedback torque are determined, including: Obtain the feedforward value of the target feedback torque from the previous moment; The original weighting coefficients for road feel feedback are determined based on the vehicle speed and the feedforward value. The product of the original weighting coefficient of the road feedback and the road switching coefficient is calculated to obtain the road feedback torque weighting coefficient, which is used as the output proportion coefficient corresponding to the road feedback torque. Calculate the difference between 1 and the road feel feedback torque weighting coefficient to obtain the basic feedback torque weighting coefficient, which is used as the output proportion coefficient corresponding to the basic feedback torque. The target feedback torque of the steering motor is determined based on the basic feedback torque, the road feel feedback torque, the basic feedback torque, and the output ratio coefficient corresponding to the road feel feedback torque, and the steering motor of the steer-by-wire system is controlled to output the target feedback torque.

2. The control method for the steer-by-wire system according to claim 1, characterized in that, The steering-related data includes: downward turning angle, steering wheel angle, and steering wheel speed; the driving control status data includes: vehicle speed and driving mode information. The basic feedback torque is determined based on the steering-related data and the driving control state data, including: Calculate the comfort rack force based on the downturn angle and the vehicle speed; The basic feedback torque is calculated based on the comfort rack force, the downturn angle, the steering wheel angle, the steering wheel speed, the vehicle speed, and the driving mode information.

3. The control method for the steer-by-wire system according to claim 2, characterized in that, The comfort rack force is calculated based on the downturn angle and the vehicle speed, including: Obtain the front wheel steering angle corresponding to the downturn angle; The lateral force of the entire vehicle is determined based on the front wheel steering angle and the vehicle speed. The original value of the comfort rack force is determined based on the lateral force of the entire vehicle. The rack force coefficient is determined based on the downward rotation angle and the vehicle speed. Calculate the product of the original value of the comfort rack force and the rack force coefficient; The product is low-pass filtered to obtain the comfort rack force.

4. The control method for the steer-by-wire system according to claim 2, characterized in that, The basic feedback torque is calculated based on the comfort rack force, the downward steering angle, the steering wheel angle, the steering wheel speed, the vehicle speed, and the driving mode information, including: The initial value of the basic feedback torque is determined based on the comfort rack force, the vehicle speed, and the driving mode information. The damping coefficient is determined based on the vehicle speed and the steering wheel rotation speed; The following feedback coefficient is determined based on the difference between the steering wheel angle and the downward steering angle; The basic feedback torque is obtained by calculating the product of the initial value of the basic feedback torque, the damping coefficient, and the following feedback coefficient.

5. The control method for the steer-by-wire system according to claim 4, characterized in that, The following feedback coefficient is determined based on the difference between the steering wheel angle and the downturn angle, including: Determine whether the difference is within a preset deviation range; If the difference is within the preset deviation range, the follow-up feedback coefficient will be set to 1; If the difference is outside the preset deviation range, the follow-up feedback coefficient is determined according to the preset natural logarithm and exponential composite function.

6. The control method for the steer-by-wire system according to claim 1, characterized in that, The steering-related data includes: the speed of the lower steering motor, the torque of the lower steering motor, the steering wheel speed, and the actual hand torque; the driving control status data includes: vehicle speed and driving mode information. Determining the road feel feedback torque based on the steering-related data and the driving control state data includes: The dynamic rack force is determined based on the speed and torque of the lower motor. The desired hand torque is determined based on the dynamic rack force, vehicle speed, and driving mode information. The road feel feedback torque is determined based on the desired hand torque, the steering wheel speed, and the actual hand torque.

7. The control method for the steer-by-wire system according to claim 6, characterized in that, Determining the dynamic rack force based on the speed and torque of the lower motor includes: The speed and torque of the lower motor are input into the dynamic mechanical model of the steer-by-wire system to obtain the original value of the dynamic rack force. The original value of the dynamic rack force is processed by dead zone processing to obtain the dynamic rack force.

8. The control method for the steer-by-wire system according to claim 6, characterized in that, Determining the road feel feedback torque based on the desired hand torque, the steering wheel speed, and the actual hand torque includes: Calculate the torque difference between the actual hand torque and the desired hand torque; The integral coefficient is determined based on the steering wheel rotation speed; The torque difference is subjected to PID closed-loop control based on the integral coefficient to obtain the road feel feedback torque.

9. The control method for the steer-by-wire system according to claim 8, characterized in that, The integral coefficient is determined based on the steering wheel rotation speed, including: Determine whether the steering wheel rotation speed is greater than the upper threshold; If the steering wheel rotation speed is greater than the upper threshold, the integral coefficient is determined to be 1; If the steering wheel speed is less than or equal to the upper threshold, determine whether the steering wheel speed is less than the lower threshold. If the steering wheel rotation speed is less than the lower threshold, the integral coefficient is determined to be 0; If the steering wheel rotation speed is greater than or equal to the lower threshold, the integral coefficient is calculated based on the steering wheel rotation speed, the upper threshold, and the lower threshold.

10. The control method for the steer-by-wire system according to claim 1, characterized in that, The target feedback torque of the steering motor is determined based on the basic feedback torque, the road feel feedback torque, the basic feedback torque, and the output proportion coefficient corresponding to the road feel feedback torque, and the steering motor of the steer-by-wire system is controlled to output the target feedback torque, including: The product of the road feedback torque and the output proportion coefficient corresponding to the road feedback torque is calculated to obtain the road feedback torque component; The basic feedback torque component is obtained by multiplying the basic feedback torque by the output proportion coefficient corresponding to the basic feedback torque. The target feedback torque is obtained by summing the road feel feedback torque component and the basic feedback torque component and then limiting the sum. The target feedback torque is output by the upper motor of the steering-by-wire system.

11. A control device for a steer-by-wire system, characterized in that, include: The acquisition module is used to acquire vehicle driving control status data and steering-related data of the steer-by-wire system; The first determining module is used to determine the basic feedback torque and road feel feedback torque based on the steering-related data and the driving control state data; The second determining module is used to determine the output proportion coefficients corresponding to the basic feedback torque and the road feel feedback torque based on the driving control state data, wherein the driving control state data includes: vehicle speed and road feel switching coefficient; determining the output proportion coefficients corresponding to the basic feedback torque and the road feel feedback torque based on the driving control state data includes: obtaining the feedforward value of the target feedback torque at the previous moment; determining the original weight coefficient of the road feel feedback based on the vehicle speed and the feedforward value; calculating the product of the original weight coefficient of the road feel feedback and the road feel switching coefficient to obtain the road feel feedback torque weight coefficient, which is used as the output proportion coefficient corresponding to the road feel feedback torque; calculating the difference between I and the road feel feedback torque weight coefficient to obtain the basic feedback torque weight coefficient, which is used as the output proportion coefficient corresponding to the basic feedback torque; The third determining module is used to determine the target feedback torque of the upper steering motor based on the basic feedback torque, the road feel feedback torque, the basic feedback torque and the output proportion coefficient corresponding to the road feel feedback torque, and control the upper steering motor of the steer-by-wire system to output the target feedback torque.

12. An electronic device, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; The processor, when executing a program stored in memory, implements the control method of the steer-by-wire system according to any one of claims 1 to 10.

13. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a program for a control method of a steer-by-wire system, which, when executed by a processor, implements the steps of the control method of the steer-by-wire system according to any one of claims 1-10.

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