Steering-by-wire system road feel establishment method and system for guiding driver takeover

Abstract

This invention provides a method and system for establishing road feel in a steer-by-wire system to guide driver takeover, relating to the field of vehicle steer-by-wire control technology. This invention avoids torque conflicts between the driver and vehicle during takeover by coordinating and unifying the control parameters of a unified model and adjusting the torque output of the unified control model. It guides the driver to safely take over by adjusting the degree of conflict, driver control, and vehicle stability margin, and smoothly establishes road feel feedback for the driver's operation, superimposing road texture excitation to provide the driver with a natural and continuous steering wheel feel. This invention is applicable to steer-by-wire systems with no or weak mechanical connection between the steering wheel and the steering actuator, and can be used in intelligent driving vehicles, driver-assisted driving vehicles, autonomous driving vehicles, and other vehicle platforms that provide automatic steering wheel following, feel feedback, and return-to-center control via a steering wheel-end motor.

Description

Technical Field

[0001] This invention relates to the field of vehicle steer-by-wire control technology, and in particular to a method and system for establishing road feel in a steer-by-wire system that guides driver takeover. Background Technology

[0002] Steer-by-wire systems eliminate or weaken the mechanical connection between the steering wheel and steering wheels in traditional mechanical steering systems. In steer-by-wire systems, the road feel simulation motor needs to provide different functions depending on the vehicle's operating state: when autonomous driving is activated, the steering wheel can turn in accordance with the steering commands of the autonomous driving system; when the driver participates in control, the steering wheel needs to gradually build up road feel and guide the driver to safely take over, so that the driver can obtain steering wheel resistance, damping, friction, and return-to-center feel close to those of traditional mechanical steering systems.

[0003] During the transition from autonomous driving to driver control, if the autonomous driving control torque is suddenly withdrawn or the driver's road feel torque is suddenly established, it can easily cause problems such as sudden changes in steering wheel torque, steering wheel wobbling, and discontinuous driver feel, potentially leading to safety issues. In a steering-by-wire system, the driver's tactile feedback to the steering wheel primarily comes from the feedback torque generated by the motor; therefore, the process of switching control must be smooth, continuous, and controllable. Driver commands during takeover can conflict with the autonomous driving system and may even threaten vehicle safety; therefore, safe guidance is necessary during the transfer of control.

[0004] In existing control methods, a common approach is to directly switch control modes based on a fixed threshold, switching the steering wheel directly from automatic driving control to driver-controlled steering. While this method is logically simple, it is prone to problems in actual driving, such as abrupt changes in control, unnatural human-machine coordination, and excessively fast or slow road feel establishment. Another approach uses a smooth curve weighting method between the driver and automatic driving systems to reconcile the conflicting feelings between the two. While this method can create a smooth steering feel, it lacks interpretability, introduces multiple control models, increases parameter tuning difficulty, and uses torque control during return to center, which can cause the steering wheel to vibrate near zero or have a large dead zone.

[0005] Therefore, a method is needed that can continuously calculate the simulated motor output based on the driver's grip state, hand torque, autonomous driving state, and steering wheel movement state using a unified control model. This method should gradually establish steering wheel road feel during the transfer of control and suppress human-machine conflict based on driver takeover efficiency, vehicle stability, and human-machine coordination, guiding the driver to safely complete takeover within safe boundaries. Furthermore, this method should be able to execute steering wheel return control when the driver is not holding the steering wheel and autonomous driving is not activated, ensuring the steering wheel stably returns to the neutral or target return position. Summary of the Invention

[0006] To address the aforementioned shortcomings in the existing technology, this invention provides a method and system for establishing road feel in a steer-by-wire system for guiding driver takeover, which solves the problem of simulating road feel in the steering system during takeover, establishing driver feel, and ensuring safety during takeover.

[0007] To achieve the above objectives, the technical solution adopted by this invention is: a method for establishing road feel in a steer-by-wire system oriented towards guiding driver takeover, comprising the following steps: S1. Collect data, store the data in the memory, and perform fault judgment in the security processing module based on the collected data. If a fault occurs, proceed to security degradation and end the process; otherwise, proceed to S2. S2. Under fault-free conditions, the autonomous driving status acquisition module determines whether the autonomous driving function is active. S3. When the driver has the intention to take over, the grip detection module calculates the strength of the intention to take over, whereby the intention to take over is... This indicates that the driver was not holding the steering wheel and did not intend to take over. This indicates that the driver is holding the steering wheel; S4. The mode is determined by the mode judgment module. When the autonomous driving function is activated and the driver does not participate in the control, the unified control model is used to generate the steering wheel target angle according to the autonomous driving steering command for the steering wheel to track. S5. When the autonomous driving function is not activated and the driver is holding the steering wheel, enter the driver independent driving mode, use the unified control model to simulate road feel, and use the dictionary basis function model to simulate road surface unevenness excitation. S6. When the automatic driving function is not activated and the driver is not holding the steering wheel, the return control mode is entered. Using the unified control model, the angle control is performed according to the predetermined return curve with the steering wheel center position or the target return position as the target, and the return torque is generated according to the angle error. S7. When the autonomous driving function is activated and the driver holds the steering wheel, the driver takeover mode is entered. In driver takeover mode, the road sense simulation motor adjusts the unified control model parameters through the parameter adjustment module based on the degree of human-machine conflict and the vehicle stability envelope margin to guide the driver to complete the takeover. Specifically, in the initial stage of takeover, the transition weights of the unified model parameters in the initial stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; in the transition stage of takeover, the transition weights of the unified model parameters in the transition stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; and in the completion stage of takeover, the transition weights of the unified model parameters in the completion stage of takeover are defined based on the vehicle stability envelope margin. S8. After the driver takes over, exit the automatic driving mode. When the driver manipulates the steering wheel beyond the preset limit angle, the equivalent stiffness and equivalent damping in the unified control model are increased to form the limit feel. When the driver returns to the preset angle range, the road feel simulation equivalent stiffness and equivalent damping are restored. S9 outputs the torque commands of the automatic driving mode, driver takeover mode, driver independent driving mode, return mode, and limit simulation to the road feel simulation motor to execute control and complete the road feel establishment of the steer-by-wire system. Among them, the driver independent driving mode and return mode have completed the takeover.

[0008] The beneficial effects of this invention are as follows: This invention coordinates and unifies the control parameters of the model, adjusts the torque output of the unified control model, avoids torque conflicts between the driver and the vehicle during the takeover process, guides the driver to take over safely by adjusting the degree of conflict, driver control, and vehicle stability margin, and smoothly establishes the driver's road feel feedback and superimposes road texture excitation to give the driver a natural and continuous steering wheel feel. This invention solves the problem of simulating steering system road feel, establishing driver feel, and ensuring safe takeover during the takeover process.

[0009] Further, S1 includes: The system powers on and completes initial configuration; Collects the original steering wheel angle, the actual or estimated torque of the road feel simulation motor at the steering wheel end, the driver's grip state, the autonomous driving activation state, the autonomous driving steering command, and vehicle status information; calculates the relative angle of the steering wheel based on the zero point of the steering wheel angle, and measures, calculates, or estimates the angular velocity of the steering wheel; Based on the collected data, fault judgment is performed in the security processing module. If a fault occurs, the system enters security degradation and terminates the process; otherwise, it proceeds to S2.

[0010] The beneficial effect of the above-mentioned further solutions is that they ensure the functional safety of the road feel simulation device in the steer-by-wire system.

[0011] Furthermore, the expression for the takeover intent is as follows:

[0012]

[0013] in, Indicating the driver's intention to take over, This indicates the driver's intention to take over at the previous moment. Indicates the sampling period. This represents the hold-up time constant. Indicates the original intention to take over. Indicates driver behavior parameters, This indicates that you need to release your hand to confirm the threshold. This indicates the hold confirmation threshold, and .

[0014] The beneficial effect of the above-mentioned further scheme is that it can not only characterize whether the driver is holding the steering wheel, but also normalize the intensity of the driver's intention to take over.

[0015] Furthermore, the expression for the unified model is as follows:

[0016] in, Indicates the torque of the road feeler motor. Indicates equivalent stiffness. Indicates equivalent damping, Indicates the current rotation angle of the road sensor motor. Indicates the reference angle of the road sensor motor. Indicates the reference angular velocity. This represents the simulated friction torque. This indicates the self-aligning torque of the tire. Represents the dictionary basis function model. This represents the total number of basis functions in the dictionary. Indicates the first The weights of the basis functions, Indicates the first A dictionary base function, Indicates the first Various dictionary basis functions, such as background texture basis functions, particle impact basis functions, and discrete event basis functions. Indicates the first Internal shape parameters of the dictionary basis functions.

[0017] The beneficial effects of the above-mentioned further solutions are: they can simulate the stiffness, damping, friction and other tactile sensations of the steering wheel, and can also superimpose the subtle tactile sensations brought by the roughness of the road surface. Furthermore, the unified control model covers autonomous driving mode, takeover mode, driver-independent driving mode, and release-to-center mode, avoiding the need for different mode switching control models.

[0018] Furthermore, the simulation of road surface unevenness excitation includes background texture excitation, particle impact excitation, and discrete event excitation; among which, The background texture layer is used to characterize the continuous road feel created by the micro-undulations of the continuous road surface at the steering wheel end. In the background texture layer, the first... The dictionary basis functions are represented as follows:

[0019] in, Represents the base functions of the background texture dictionary. Represents the amplitude modulation function. Represents harmonic frequency parameters. Represents the phase parameter. Represents the amplitude coefficient of a random function. Represents a random function; The particulate impact layer is used to characterize the localized impact and vibration sensations caused by sand, gravel, or granular road surfaces. The dictionary basis functions of the particulate impact layer are expressed using locally damped oscillating basis functions:

[0020] in, Represents the basis functions of the particle impact dictionary. Indicates the attenuation parameter. Represents harmonic frequency parameters. Indicates the phase parameter; The discrete event layer is used to characterize road surface events such as joints, manhole covers, speed bumps, edge steps, and short-term sudden events. The single-peak pulse is represented as a basis function in the discrete event dictionary as follows:

[0021] in, Represents the dictionary basis functions for discrete events. This parameter represents the duration of a single-peak pulse.

[0022] The beneficial effect of the above-mentioned further scheme is that it simulates the steering wheel vibration effect caused by complex, high-frequency, and random road surface roughness through weighted summation using trigonometric functions as basis functions, providing a more realistic feel; Furthermore, when entering the homing control mode, the parameters of the unified model are expressed as follows:

[0023] in, Indicates the reference angle of the road sensor motor. This indicates the target turning angle output by the return curve. Indicates equivalent stiffness. Indicates the stiffness when returning to center. Indicates equivalent damping, Indicates the damping during the return to center position. This represents the simulated friction torque. This indicates friction compensation during the return-to-center process.

[0024] The beneficial effects of the above-mentioned further scheme are: the return-to-center mode adopts the same control model as other modes, but achieves tracking of the return-to-center position, avoids zero-point oscillation, and reduces control complexity; Furthermore, the expression for the degree of human-machine conflict is as follows:

[0025] in, Indicates the degree of human-machine conflict. Indicates the current rotation angle of the road sensor motor. This indicates a cornering command from the autonomous driving system. Indicates the normalization benchmark for corner conflict. This indicates the current angular velocity of the road sensor motor. This indicates the angular velocity command for the autonomous driving system. Indicates the normalized reference for angular velocity; The expression for the vehicle stability envelope margin is as follows:

[0026] in, Indicates the vehicle stability envelope margin. Indicates yaw rate. This indicates the lateral displacement deviation. and These represent the safety boundaries for yaw rate and lateral displacement deviation, respectively.

[0027] The beneficial effects of the above-mentioned further solutions are: through the above solutions, conflict indicators and vehicle stability indicators are provided for the establishment of road sense during the driver takeover process, and indicators are provided for reducing human-machine conflict and ensuring vehicle safety in the subsequent road sense establishment process; Furthermore, the expression for the transition weights of the unified model parameters in the initial stage of takeover is as follows:

[0028] in, This indicates the transition weights for the unified model parameters during the initial stage of takeover. Indicating the driver's intention to take over, Indicates the degree of human-machine conflict. Indicates the vehicle stability envelope margin; In the initial stage of takeover, the parameter changes of the unified control model are represented as follows:

[0029] in, Indicates equivalent stiffness. This represents the equivalent stiffness at the previous moment. This represents the equivalent stiffness when the driver is driving independently. Indicates equivalent damping, This indicates the equivalent damping at the previous moment. This represents the equivalent damping when the driver is driving independently. This represents the simulated friction torque. This represents the simulated friction torque at the previous moment. This represents the simulated friction torque when the driver is driving independently. Indicates the reference angle of the road sensor motor. This indicates the reference angle of the road sensor motor at the previous moment. , , , Represents equivalent stiffness initial value, express, Indicates equivalent damping initial value, express, Indicates simulated friction torque The initial value.

[0030] The beneficial effect of the above-mentioned further solution is that, when no human-machine conflict is apparent in the initial stage of takeover, the technical solution will smoothly transition the unified model control parameters from automatic driving parameters to driver-independent driving parameters. Furthermore, the expression for the transition weights of the unified model parameters during the takeover transition phase is as follows:

[0031] in, This indicates the transition weights of the unified model parameters during the takeover transition phase. Indicating the driver's intention to take over, Indicates the degree of human-machine conflict. Indicates the vehicle stability envelope margin; During the takeover transition phase, the parameter changes of the unified control model are represented as follows:

[0032] in, Indicates equivalent stiffness. This represents the equivalent stiffness at the previous moment. This represents the equivalent stiffness when the driver is driving independently. Indicates equivalent damping, This indicates the equivalent damping at the previous moment. This represents the equivalent damping when the driver is driving independently. This indicates the compensatory damping associated with the transition phase and conflict. This represents the simulated friction torque. This represents the simulated friction torque at the previous moment. This represents the simulated friction torque when the driver is driving independently. Indicates the reference angle of the road sensor motor. This indicates the reference rotation angle of the road sensor motor at the previous moment.

[0033] The beneficial effects of the above-mentioned further solution are: the technical solution is used to further strengthen the driver's intention to take over, and when human-machine conflict becomes prominent, the speed at which driving authority is transferred from automatic driving to driver is determined based on the driver's intention to take over, the degree of conflict, and the safety envelope; Furthermore, the expression for the transition weights of the unified model parameters in the takeover completion phase is as follows:

[0034] in, This indicates the transition weights of the unified model parameters during the takeover completion phase. Indicating the driver's intention to take over, Indicates the vehicle stability envelope margin; During the takeover completion phase, the parameter changes of the unified control model are represented as follows:

[0035] in, Indicates equivalent stiffness. This represents the equivalent stiffness when the driver is driving independently. Indicates protective stiffness. Indicates equivalent damping, This represents the equivalent damping when the driver is driving independently. Indicates protective damping. This represents the simulated friction torque. Indicates protective friction torque. This indicates the reference rotation angle of the road sensor motor.

[0036] The beneficial effect of the above-mentioned further solution is that when the driver's stable grip on the steering wheel has become dominant, the parameters are mainly based on the parameters when the driver is driving independently. However, the safety envelope still serves as the underlying protection mechanism to prevent the system from losing its restraint capability when the vehicle approaches the safety boundary.

[0037] The present invention also provides a road feel establishment system for a steer-by-wire system oriented towards guiding driver takeover, comprising: The security processing module is used to collect data, store the data in the memory, and perform fault judgment based on the collected data. If a fault occurs, it enters the security degradation stage and ends the process; otherwise, it enters the second processing module. The autonomous driving status acquisition module is used to determine whether the autonomous driving function is active under fault-free conditions. The grip detection module is used to calculate the strength of the driver's intent to take over, whereby the intent to take over is... This indicates that the driver was not holding the steering wheel and did not intend to take over. This indicates that the driver is holding the steering wheel; The mode determination module is used to generate a target steering wheel angle based on the autonomous driving steering command when the autonomous driving function is activated and the driver is not involved in the control, so that the steering wheel can track it. The road feel simulation module is used to enter the driver-independent driving mode when the autonomous driving function is not activated and the driver is holding the steering wheel. It uses a unified control model to simulate road feel and a dictionary basis function model to simulate road surface unevenness excitation. The return-to-center control module is used to enter the return-to-center control mode when the autonomous driving function is not activated and the driver is not holding the steering wheel. It uses a unified control model to perform angle control according to a predetermined return-to-center curve with the steering wheel center position or the target return-to-center position as the target, and generates return-to-center torque based on the angle error. The parameter adjustment module is used to guide the driver to take over when the autonomous driving function is activated and the driver is holding the steering wheel and entering the driver takeover mode. In the driver takeover mode, the road sense simulation motor guides the driver to complete the takeover by adjusting the unified control model parameters based on the degree of human-machine conflict and the vehicle stability envelope margin. Specifically, in the initial stage of takeover, the transition weights of the unified model parameters in the initial stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; in the transition stage of takeover, the transition weights of the unified model parameters in the transition stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; and in the completion stage of takeover, the transition weights of the unified model parameters in the completion stage of takeover are defined based on the vehicle stability envelope margin. The limit simulation module is used to disengage autonomous driving after the driver takes over. When the driver manipulates the steering wheel beyond the preset limit angle, the limit feel is generated by increasing the equivalent stiffness and equivalent damping in the unified control model. When the driver returns to the preset angle range, the road feel simulation equivalent stiffness and equivalent damping are restored. The execution control module is used to output torque commands for the automatic driving mode, driver takeover mode, driver independent driving mode, return-to-center mode, and limit simulation to the road feel simulation motor, execute control, and complete the road feel establishment for the steer-by-wire system. Among them, the driver independent driving mode and return-to-center mode indicate that the driver has taken over the steering.

[0038] The beneficial effects of this invention are: This invention coordinates and unifies the control parameters of the unified control model, adjusts the torque output of the unified control model, avoids torque conflicts between the driver and the vehicle during takeover, guides the driver to take over safely by adjusting the degree of conflict, driver control, and vehicle stability margin, smoothly establishes driver road feel feedback, and superimposes road texture excitation to give the driver a natural and continuous steering wheel feel. This invention has at least the following beneficial effects: 1. This invention proposes a unified control model for steer-by-wire road feel simulation. The same control expression method is used in automatic driving, driver takeover, driver independent driving, release and return to center, and soft limit. Only by smoothly switching parameters can the control requirements of the road feel simulation motor in different modes be met.

[0039] 2. This invention gradually establishes steering wheel road feel through smooth parameter transition, enabling the driver to establish a continuous and natural simulated road feel during the control process.

[0040] 3. This invention guides the driver to take over based on the safety envelope and the degree of conflict, and reduces the degree of conflict during the process to ensure the safety of the takeover.

[0041] 4. This invention superimposes a road surface unevenness excitation model on the steering wheel feel. By setting three unevenness models with a unified expression form, it realizes the simulation of the feel of background texture, particle impact, and discrete events.

[0042] 5. When the steering wheel enters the limit area, a natural limit feel is achieved by increasing the equivalent stiffness and equivalent damping.

[0043] 6. When the driver is not holding the steering wheel and the automatic driving system is not activated, the steering wheel is smoothly returned to center through angle control and torque closed loop, avoiding the oscillation and overshoot caused by pure torque mode. Attached Figure Description

[0044] Figure 1 The overall flowchart of the method for smooth transfer of autonomous driving permissions and driver road sense establishment control in this invention is shown in the figure.

[0045] Figure 2 This is a flowchart of the takeover phase of the present invention.

[0046] Figure 3 This is a schematic diagram of the steering wheel end control system structure of the present invention.

[0047] Figure 4 This is a schematic diagram illustrating the road surface unevenness excitation effect of the present invention.

[0048] Figure 5 This is a schematic diagram of the system structure of the present invention. Detailed Implementation

[0049] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0050] Example 1 like Figure 1 and Figure 3 As shown, this invention provides a method for establishing road feel in a steer-by-wire system to guide driver takeover, and its implementation method is as follows: S1. Collect and store data in the memory. Based on the collected data, perform fault judgment in the security processing module. If a fault occurs, proceed to security degradation and end the process; otherwise, proceed to S2. The implementation method is as follows: The system powers on and completes initial configuration; The system acquires the original steering wheel angle using an angle sensor, acquires the actual or estimated torque of the road feel simulation motor at the steering wheel end using a torque sensor, detects the driver's grip state using a grip detection module, acquires the autonomous driving activation state and autonomous driving steering commands using an autonomous driving status acquisition module, and acquires vehicle status information using a vehicle status acquisition module; it calculates the relative angle of the steering wheel based on the zero point of the steering wheel angle, and measures, calculates, or estimates the angular velocity of the steering wheel. Based on the collected data, the security module performs fault diagnosis. If a fault occurs, the system enters a security degradation phase and terminates the process; otherwise, it proceeds to S2. S2. Under fault-free conditions, the autonomous driving status acquisition module determines whether the autonomous driving function is active. S3. When the driver has the intention to take over, the grip detection module calculates the strength of the intention to take over, whereby the intention to take over is... This indicates that the driver was not holding the steering wheel and did not intend to take over. This indicates that the driver is holding the steering wheel; S4. The mode is determined by the mode judgment module. When the autonomous driving function is activated and the driver does not participate in the control, the unified control model is used to generate the steering wheel target angle according to the autonomous driving steering command for the steering wheel to track. S5. When the autonomous driving function is not activated and the driver is holding the steering wheel, enter the driver independent driving mode, use the unified control model to simulate road feel, and use the dictionary basis function model to simulate road surface unevenness excitation. S6. When the automatic driving function is not activated and the driver is not holding the steering wheel, the return control mode is entered. Using the unified control model, the angle control is performed according to the predetermined return curve with the steering wheel center position or the target return position as the target, and the return torque is generated according to the angle error. S7. When the autonomous driving function is activated and the driver holds the steering wheel, the driver takeover mode is entered. In driver takeover mode, the road sense simulation motor adjusts the unified control model parameters through the parameter adjustment module based on the degree of human-machine conflict and the vehicle stability envelope margin to guide the driver to complete the takeover. Specifically, in the initial stage of takeover, the transition weights of the unified model parameters in the initial stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; in the transition stage of takeover, the transition weights of the unified model parameters in the transition stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; and in the completion stage of takeover, the transition weights of the unified model parameters in the completion stage of takeover are defined based on the vehicle stability envelope margin. S8. After the driver takes over, the automatic driving is discontinued. When the driver manipulates the steering wheel beyond the preset limit angle, the equivalent stiffness and equivalent damping in the unified control model are increased to form a limit feel. When the driver returns to the preset angle range, the road feel simulation equivalent stiffness and equivalent damping are restored. S9. Output the torque commands of the automatic driving mode, driver takeover mode, driver independent driving mode, return to center mode, and limit simulation to the motor driver to control the road feel motor, execute the control, and complete the road feel establishment of the steer-by-wire system. Among them, the driver independent driving mode and return to center mode are the ones where the takeover has been completed.

[0051] This invention provides a control method for smooth transfer of autonomous driving privileges and driver road sense establishment in a steer-by-wire system. It involves autonomous driving mode, driver takeover mode, driver independent driving mode, and hands-free return-to-center mode. Although the control objectives of these modes differ, this invention proposes a unified control model that can implement different control modes with a single control architecture. The unified control model is as follows: (1) in, Indicates the torque of the road feeler motor. Indicates equivalent stiffness. Indicates equivalent damping, Indicates the current rotation angle of the road sensor motor. Indicates the reference angle of the road sensor motor. This indicates the current steering angular velocity of the road sensor motor. Indicates the reference angular velocity. This represents the simulated friction torque. This indicates the self-aligning torque of the tire. Represents the dictionary basis function model. This represents the total number of basis functions in the dictionary. Indicates the first The weights of the basis functions, Indicates the first A dictionary base function, Indicates the first Various dictionary basis functions, such as background texture basis functions, particle impact basis functions, and discrete event basis functions. Indicates the first Internal shape parameters of the dictionary basis functions.

[0052] In this embodiment, a unified control method is used to control the torque of the road sensor motor in each mode, including the following steps: Step 1: Power on and initialize the system The system powers on and starts up, completes initial configuration, and reads the steering wheel angle zero point, angle limit, torque limit, road feel parameters, return-to-center parameters, and safety parameters from the memory.

[0053] Step 2: Data Collection The system acquires the original steering wheel angle using an angle sensor, and the actual or estimated torque of the road-sensing simulation motor at the steering wheel end using a torque sensor. It also detects the driver's grip state using a grip detection module, obtains the autonomous driving activation state and autonomous driving steering commands using an autonomous driving status acquisition module, and acquires vehicle status information using a vehicle status acquisition module. The system calculates the relative angle of the steering wheel based on the zero point of the steering wheel angle, and measures, calculates, or estimates the angular velocity of the steering wheel.

[0054] Step 3: Determine if there is a malfunction. Based on the data collected in step 2, fault diagnosis is performed in the security module. If a fault occurs, proceed to step 4; otherwise, proceed to step 5.

[0055] Step 4: Security Downgrade When a system malfunctions, safety degradation control is implemented by reducing torque output and limiting steering angle to ensure system safety.

[0056] Step 5: Determine if autonomous driving is activated. Under fault-free system conditions, the autonomous driving status acquisition module determines whether the autonomous driving function is active and defines the autonomous driving status. Activated for autonomous driving, when Autonomous driving is not activated.

[0057] Step 6: Calculate the strength of the driver's intent to take over The grip detection module determines whether the driver has a takeover intention and calculates the strength of the intention. Based on the intention, the system enters takeover mode and guides the parameter transition of the unified control model. Generally, the takeover intention is calculated based on the driver's behavior. One behavior-based formula for calculating driver takeover intention is as follows: (2) in, Indicating the driver's intention to take over, This indicates the driver's intention to take over at the previous moment. Indicates the sampling period. This represents the hold-up setup time constant, used to suppress sensor jitter and momentary misjudgments. The original intent to take over can be calculated based on the following formula: (3) in, This represents driver behavior parameters, which are determined by the sensors used, such as hand torque obtained by a torque sensor and grip force obtained by a capacitive sensor. This indicates the holding confirmation threshold. This indicates that releasing the hand confirms the threshold, and... , This indicates that the driver was not holding the steering wheel. This indicates when the driver is holding the steering wheel.

[0058] Autopilot mode Step 7: Autonomous Driving Corner Tracking when and When autonomous driving is activated and the driver is not involved in control, a target steering wheel angle is generated based on the autonomous driving steering command for the steering wheel to track. Then the parameters in equation (1) are: (4) in, This indicates the target turning angle output by the autonomous driving system. This represents the stiffness during autonomous driving angle tracking. This indicates the damping during autonomous driving angle following. This represents the friction compensation term. At this point, in equation (1)... and It can be set to 0. Reference angular velocity It can be obtained from the reference angle difference.

[0059] Driver Independent Driving Mode Step 8: Road feel simulation based on a unified control model under independent driver driving.

[0060] when and At that time, the unified control model shown in equation (1) is adopted, and the parameters are set as follows: (5) in, Indicates equivalent stiffness. This represents the equivalent stiffness when the driver is driving independently. Indicates equivalent damping, This represents the equivalent damping when the driver is driving independently. This represents the simulated friction torque. This represents the simulated friction torque when the driver is driving independently.

[0061] Step 9: Road surface roughness excitation based on dictionary basis function model like Figure 4 As shown, when the driver is driving independently, road sense is superimposed with road surface roughness excitation. The road surface roughness excitation torque based on the dictionary basis function model is expressed by the following formula: (6) in, This represents the total number of basis functions in the dictionary. Indicates the first The weights of the basis functions, Indicates the first A dictionary base function, Indicates the first Various dictionary basis functions, such as background texture basis functions, particle impact basis functions, and discrete event basis functions. Indicates the first Internal shape parameters of the dictionary basis functions.

[0062] The dictionary basis function model shown in the above equation can be used to uniformly represent the excitation of a three-layer road surface.

[0063] Background texture layer: This layer is used to characterize the continuous road feel created at the steering wheel end by the micro-undulations of continuous road surfaces such as ordinary roads and rough asphalt. Preferably, in the background texture layer, the first... A dictionary basis function can be represented as: (7) in, Represents the base functions of the background texture dictionary. This represents the amplitude modulation function, preferably a slowly varying envelope modulation function. This represents the harmonic frequency parameter; the higher the frequency, the rougher the road surface. Represents the phase parameter. Represents the amplitude coefficient of a random function. The random function can be selected as a zero-mean random noise sequence or a random sequence after low-pass or band-pass filtering. The background texture excitation is obtained by weighted summation of multiple equations (10). Optionally, equation (10) is a combination of a cosine function and a random function.

[0064] Particulate Impact Layer: This layer characterizes the localized impact and vibration sensations caused by sand, gravel, or granular road surfaces. Preferably, the dictionary basis functions of the particulate impact layer employ locally damped oscillating basis functions, which can be selected as follows: (8) in, Represents the basis functions of the particle impact dictionary. Indicates the attenuation parameter. Represents harmonic frequency parameters. The phase parameter is represented by the particle impact excitation, which is obtained by weighted summation of multiple equations (8). Optionally, equation (8) is in the form of a cosine function.

[0065] Discrete Event Layer: This layer is used to characterize joints, manhole covers, speed bumps, edge steps, and similar short-term, sudden road surface events. Preferably, single-peak pulses are used as the basis functions for the discrete event dictionary. (9) in, Represents the dictionary basis functions for discrete events. This represents the duration parameter of a single-peak pulse. Optionally, double-peak pulses and damped pulses can also be used as dictionary basis functions for discrete events. The discrete event layer can be constructed by weighted superposition of one or more dictionary basis functions from multiple single-peak pulses, double-peak pulses, and damped pulses.

[0066] The overall road surface excitation is a combination of background texture excitation, particle impact excitation, and discrete event excitation.

[0067] Release to return to center mode Step 10: Release the lever to return to center control when and When the driver is not holding the steering wheel and the automatic driving system is not activated, the system enters the return-to-center control mode. Using the center position of the steering wheel or the target return-to-center position as the target, it performs angle control according to a predetermined return-to-center curve and generates return-to-center torque based on the angle error. The parameters of the unified control model in this mode are: (10) in, Indicates the reference angle of the road sensor motor. This indicates the target turning angle output by the return curve. Indicates equivalent stiffness. Indicates the stiffness when returning to center. Indicates equivalent damping, Indicates the damping during the return to center position. This represents the simulated friction torque. This indicates friction compensation during the return-to-center process.

[0068] like Figure 2 As shown, the driver takeover mode is as follows.

[0069] Step 11: When and When the autonomous driving mode is activated and the driver holds the steering wheel, the driver takes over mode. In this mode, the road sense simulation motor will guide the driver to take over by adjusting the parameters of the unified control model based on the degree of human-machine conflict and the vehicle stability envelope.

[0070] Step 12: Calculate the degree of conflict between the driver and the autonomous driving system. Based on the conflict between the driver and the autonomous driving system, the parameters of the unified control model are adjusted. The greater the conflict between the driver and the autonomous driving system, the more the system should suppress rapid transitions and enhance dissipation support. A conflict index between the driver and the autonomous driving system is defined to describe the degree of antagonism between the driver's current driving trend and the autonomous driving objective. (11) in, Indicates the degree of human-machine conflict. Indicates the current rotation angle of the road sensor motor. This indicates a cornering command from the autonomous driving system. Indicates the normalization benchmark for corner conflict. This indicates the current angular velocity of the road sensor motor. This indicates the angular velocity command for the autonomous driving system. This represents the normalized reference for angular velocity.

[0071] Step 13: Calculate the vehicle stability envelope margin Based on the vehicle's lateral stability margin, adjust the parameters of the unified control model. If the vehicle's stability margin is small, the system should limit the impedance transition speed and retain additional stability support. The vehicle stability envelope margin is defined as follows: (12) in, Indicates yaw rate. This indicates the lateral displacement deviation. and These represent the safety boundaries for yaw rate and lateral displacement deviation, respectively.

[0072] Step 14: Initial Takeover Phase The initial takeover phase indicates that the driver begins to show an intention to take over, and there may have been an initial conflict between the human and the machine, but the automated system still maintains dominance. and It has begun to rise, but is still at a low level. The weights of the unified model parameters for this stage are defined as follows: (13) in, This indicates that the unified model parameters take over the transition weights in the initial stage. Indicating the driver's intention to take over, Indicates the degree of human-machine conflict. Indicates the vehicle stability envelope margin; As can be seen, since the takeover has just begun, only minor adjustments have been made to the parameters, and when the safety margin is large, The parameters can be relatively larger, with more significant adjustments made towards the driver. When the safety margin is small, the system only makes conservative, minor adjustments.

[0073] The parameter variations of the unified control model can be expressed as: (14) in, Indicates equivalent stiffness. This represents the equivalent stiffness at the previous moment. This represents the equivalent stiffness when the driver is driving independently. Indicates equivalent damping, This indicates the equivalent damping at the previous moment. This represents the equivalent damping when the driver is driving independently. This represents the simulated friction torque. This represents the simulated friction torque at the previous moment. This represents the simulated friction torque when the driver is driving independently. Indicates the reference angle of the road sensor motor. This indicates the reference angle of the road sensor motor at the previous moment. , , , Represents equivalent stiffness initial value, This represents the stiffness during autonomous driving angle tracking. Indicates equivalent damping initial value, This indicates the damping during autonomous driving angle following. Indicates simulated friction torque The initial value.

[0074] Step 15: Takeover Transition Phase The takeover transition phase indicates that the driver's intention to take over is relatively clear, the level of human-machine conflict may further increase, and control needs to be continuously transferred from the automated system to the driver. This phase... and It is already at a medium or high level. The weights of the unified model parameters for this stage are defined as follows: (15) in, This indicates that the unified model parameters take over the transition weights. Indicating the driver's intention to take over, Indicates the degree of human-machine conflict. Indicates the vehicle stability envelope margin; Compared to the initial stage, the parameters can now transition more significantly towards driver-led directions. The parameter variations of the unified control model can be expressed as: (16) in, Indicates equivalent stiffness. This represents the equivalent stiffness at the previous moment. This represents the equivalent stiffness when the driver is driving independently. Indicates equivalent damping, This indicates the equivalent damping at the previous moment. This represents the equivalent damping when the driver is driving independently. This indicates the compensatory damping associated with the transition phase and conflict. This represents the simulated friction torque. This represents the simulated friction torque at the previous moment. This represents the simulated friction torque when the driver is driving independently. Indicates the reference angle of the road sensor motor. This indicates the reference angle of the road sensor motor at the previous moment. , , , The initial value is the final value during the initial stage of takeover. This is used to increase damping when there is significant conflict during the transition phase, in order to reduce the feeling of resistance to the steering wheel. The above formula also shows that when the safety margin is large, the parameters transition more fully to the driver's side, while when the safety margin is small, the parameter adjustment is more cautious.

[0075] Step 16: Takeover Completion Phase The takeover completion phase indicates that the driver's intention to take over has been firmly established, and the transfer of system control is essentially complete. At this point, the parameters of the unified control model have been adjusted to near the parameters used when the driver was driving independently, and the driver's intention to take over is strong. However, safety margins continue to limit the range of parameter adjustments to prevent the complete relaxation of system constraints under low safety margins. The transition weights of the unified model parameters in this phase are defined as follows: (17) in, This indicates the transition weights during the unified model parameter takeover phase. Indicating the driver's intention to take over, Indicates the vehicle stability envelope margin; During this phase, the driver's intentions are the primary consideration, but certain constraints on the automatic system are still maintained when the safety margin is low.

[0076] The parameter variations of the unified control model can be expressed as: (18) in, Indicates equivalent stiffness. This represents the equivalent stiffness when the driver is driving independently. Indicates protective stiffness. Indicates equivalent damping, This represents the equivalent damping when the driver is driving independently. Indicates protective damping. This represents the simulated friction torque. Indicates protective friction torque. This represents the reference angle of the road sensor motor. It can be seen that when the safety margin is large, the parameters of the unified control model more closely follow the driver's intentions, and the stiffness, damping, and friction are closer to the driver's dominant parameters. When the safety margin is small, the system will appropriately increase the protective stiffness, damping, and friction, while retaining a portion of the automatic system's reference angle, thereby enhancing safety constraints.

[0077] Step 17: Determine whether autonomous driving has disengaged. The takeover completion conditions are defined as follows: (19) in, This indicates the exit flag. Indicates the reference angle of the road sensor motor. This indicates the actual rotation angle of the road sensor motor. Indicates equivalent stiffness. Indicates the stiffness when the driver is driving alone. Indicates equivalent damping, This indicates the damping when the driver is driving independently. , , These represent the reference angle error threshold, stiffness error threshold, and damping error threshold, respectively. express The duration of 1 This indicates the confirmation time for completion of takeover; the meaning of the above formula is when the equivalent stiffness... Equivalent damping Reference angle All of them have been moved to the vicinity of the driver's independent driving simulation road feel parameters. , , After stabilizing for a period of time, it can be determined that the takeover is complete and the autonomous driving will disengage.

[0078] Step 18: Soft limiter.

[0079] Soft limits function in driver-independent driving and takeover modes to simulate the angular constraints of a mechanical steering system. When the driver manipulates the steering wheel beyond a preset limit angle, the controller increases the equivalent stiffness and equivalent damping in the unified control model to create a limiting feel. In automatic driving and steering wheel return modes, no tactile feedback is required, so soft angular constraints are sufficient.

[0080] Let the soft limit trigger angle of the steering wheel be... When the following conditions are met: (20) in, Indicates the actual rotation angle of the road sensor motor The system determines that the steering wheel has entered the enhanced limit zone. Within the enhanced limit zone... (twenty one) in, Indicates the reference angle of the road sensor motor. Indicates equivalent stiffness. Indicates equivalent damping, The stiffness function represents the stiffness under soft constraint. The damping function represents the soft-limited position. It can make the steering wheel produce a clear sense of angle boundaries and a tendency to return to center. This makes the steering wheel feel more resistant when it continues to turn rapidly toward its limit.

[0081] The limit stiffness function and limit damping function can be determined based on the steering wheel over-limit, steering wheel angular velocity, vehicle speed, and driving mode. Specific implementation methods can include adaptive laws, calibration lookup tables, piecewise calibration curves, continuous smooth functions, or combinations thereof.

[0082] When the steering wheel returns from the limit area to the center position, the controller can reduce the equivalent damping in the limit area, allowing the driver to smoothly return the steering wheel while maintaining appropriate stiffness to provide a tendency to return to center.

[0083] Step 19: Road feel simulates motor execution.

[0084] The torque commands for the autonomous driving mode, driver takeover mode, driver independent driving mode, and return-to-center mode are output to the motor driver to control the road sensor motor, which then performs the corresponding control.

[0085] Example 2 like Figure 5 As shown, the present invention provides a road feel establishment system for a steer-by-wire system oriented towards guiding driver takeover, used to execute the road feel establishment method for a steer-by-wire system described in Embodiment 1, comprising: The security processing module is used to collect data, store the data in the memory, and perform fault judgment based on the collected data. If a fault occurs, it enters the security degradation stage and ends the process; otherwise, it enters the second processing module. The autonomous driving status acquisition module is used to determine whether the autonomous driving function is active under fault-free conditions. The grip detection module is used to calculate the strength of the driver's intent to take over, whereby the intent to take over is... This indicates that the driver was not holding the steering wheel and did not intend to take over. This indicates that the driver is holding the steering wheel; The mode determination module is used to generate a target steering wheel angle based on the autonomous driving steering command when the autonomous driving function is activated and the driver is not involved in the control, so that the steering wheel can track it. The road feel simulation module is used to enter the driver-independent driving mode when the autonomous driving function is not activated and the driver is holding the steering wheel. It uses a unified control model to simulate road feel and a dictionary basis function model to simulate road surface unevenness excitation. The return-to-center control module is used to enter the return-to-center control mode when the autonomous driving function is not activated and the driver is not holding the steering wheel. It uses a unified control model to perform angle control according to a predetermined return-to-center curve with the steering wheel center position or the target return-to-center position as the target, and generates return-to-center torque based on the angle error. The parameter adjustment module is used to guide the driver to take over when the autonomous driving function is activated and the driver is holding the steering wheel and entering the driver takeover mode. In the driver takeover mode, the road sense simulation motor guides the driver to complete the takeover by adjusting the unified control model parameters based on the degree of human-machine conflict and the vehicle stability envelope margin. Specifically, in the initial stage of takeover, the transition weights of the unified model parameters in the initial stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; in the transition stage of takeover, the transition weights of the unified model parameters in the transition stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; and in the completion stage of takeover, the transition weights of the unified model parameters in the completion stage of takeover are defined based on the vehicle stability envelope margin. The limit simulation module is used to disengage autonomous driving after the driver takes over. When the driver manipulates the steering wheel beyond the preset limit angle, the limit feel is generated by increasing the equivalent stiffness and equivalent damping in the unified control model. When the driver returns to the preset angle range, the road feel simulation equivalent stiffness and equivalent damping are restored. The execution control module is used to output torque commands for the automatic driving mode, driver takeover mode, driver independent driving mode, return to center mode, and limit simulation to the road feel simulation motor, execute control, and complete the road feel establishment for the steer-by-wire system. Among them, the driver independent driving mode and return to center mode indicate that the driver has taken over the control.

[0086] The steer-by-wire system road feel establishment system provided in this embodiment can execute the technical solution shown in the above method embodiment 1. Its implementation principle and beneficial effects are similar, and will not be repeated here.

[0087] In this embodiment, the functional units can be divided according to the road feel establishment method of the steer-by-wire system. For example, each function can be divided into its own functional unit, or two or more functions can be integrated into one processing unit. The integrated unit can be implemented in hardware or as a software functional unit. It should be noted that the division of units in this invention is illustrative and only represents a logical division; other division methods may be used in actual implementation.

[0088] In this embodiment, the steer-by-wire system road feel establishment system, in order to achieve the principles and beneficial effects of Embodiment 1, includes hardware structures and / or software modules corresponding to the execution of various functions. Those skilled in the art should readily recognize that, in conjunction with the illustrative units and algorithm steps described in the embodiments disclosed herein, this invention can be implemented in hardware and / or a combination of hardware and computer software. Whether a function is executed by hardware or computer software depends on the specific application and design constraints of the technical solution. Different methods can be used to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

Claims

1. A method for establishing road feel in a steer-by-wire system oriented towards guiding driver takeover, characterized in that, Includes the following steps: S1. Collect data, store the data in the memory, and perform fault judgment in the security processing module based on the collected data. If a fault occurs, proceed to security degradation and end the process; otherwise, proceed to S2. S2. Under fault-free conditions, the autonomous driving status acquisition module determines whether the autonomous driving function is active. S3. When the driver has the intention to take over, the grip detection module calculates the strength of the intention to take over, whereby the intention to take over is... This indicates that the driver was not holding the steering wheel and did not intend to take over. This indicates that the driver is holding the steering wheel; S4. The mode is determined by the mode judgment module. When the autonomous driving function is activated and the driver does not participate in the control, the unified control model is used to generate the steering wheel target angle according to the autonomous driving steering command for the steering wheel to track. S5. When the autonomous driving function is not activated and the driver is holding the steering wheel, enter the driver independent driving mode, use the unified control model to simulate road feel, and use the dictionary basis function model to simulate road surface unevenness excitation. S6. When the automatic driving function is not activated and the driver is not holding the steering wheel, the return control mode is entered. Using the unified control model, the angle control is performed according to the predetermined return curve with the steering wheel center position or the target return position as the target, and the return torque is generated according to the angle error. S7. When the autonomous driving function is activated and the driver holds the steering wheel, the driver takeover mode is entered. In driver takeover mode, the road sense simulation motor adjusts the unified control model parameters through the parameter adjustment module based on the degree of human-machine conflict and the vehicle stability envelope margin to guide the driver to complete the takeover. Specifically, in the initial stage of takeover, the transition weights of the unified model parameters in the initial stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; in the transition stage of takeover, the transition weights of the unified model parameters in the transition stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; and in the completion stage of takeover, the transition weights of the unified model parameters in the completion stage of takeover are defined based on the vehicle stability envelope margin. S8. After the driver takes over, exit the automatic driving mode. When the driver manipulates the steering wheel beyond the preset limit angle, the equivalent stiffness and equivalent damping in the unified control model are increased to form the limit feel. When the driver returns to the preset angle range, the road feel simulation equivalent stiffness and equivalent damping are restored. S9 outputs the torque commands of the automatic driving mode, driver takeover mode, driver independent driving mode, return mode, and limit simulation to the road feel simulation motor to execute control and complete the road feel establishment of the steer-by-wire system. Among them, the driver independent driving mode and return mode have completed the takeover.

2. The method for establishing road feel in a steer-by-wire system for guiding driver takeover as described in claim 1, characterized in that, S1 includes: The system powers on and completes initial configuration; Collects the original steering wheel angle, the actual or estimated torque of the road feel simulation motor at the steering wheel end, the driver's grip state, the autonomous driving activation state, the autonomous driving steering command, and vehicle status information; calculates the relative angle of the steering wheel based on the zero point of the steering wheel angle, and measures, calculates, or estimates the angular velocity of the steering wheel; Based on the collected data, fault judgment is performed in the security processing module. If a fault occurs, the system enters security degradation and terminates the process; otherwise, it proceeds to S2.

3. The method for establishing road feel in a steer-by-wire system for guiding driver takeover as described in claim 1, characterized in that, The expression for the takeover intent is as follows: in, Indicating the driver's intention to take over, This indicates the driver's intention to take over at the previous moment. Indicates the sampling period. This represents the hold-up time constant. Indicates the original intention to take over. Indicates driver behavior parameters, This indicates that you need to release your hand to confirm the threshold. This indicates the hold confirmation threshold, and .

4. The method for establishing road feel in a steer-by-wire system for guiding driver takeover as described in claim 1, characterized in that, The expression for the unified model is as follows: in, Indicates the torque of the road feeler motor. Indicates equivalent stiffness. Indicates equivalent damping, Indicates the current rotation angle of the road sensor motor. Indicates the reference angle of the road sensor motor. This indicates the current steering angular velocity of the road sensor motor. Indicates the reference angular velocity. This represents the simulated friction torque. This indicates the self-aligning torque of the tire. Represents the dictionary basis function model. This represents the total number of basis functions in the dictionary. Indicates the first The weights of the basis functions, Indicates the first A dictionary base function, Indicates the first Various dictionary basis functions, such as background texture basis functions, particle impact basis functions, and discrete event basis functions. Indicates the first Internal shape parameters of the dictionary basis functions.

5. The method for establishing road feel in a steer-by-wire system for guiding driver takeover as described in claim 1, characterized in that, The simulation of road surface roughness excitation includes background texture excitation, particle impact excitation, and discrete event excitation; among them, The background texture layer is used to characterize the continuous road feel created by the micro-undulations of the continuous road surface at the steering wheel end. In the background texture layer, the first... The dictionary basis functions are represented as follows: in, Represents the base functions of the background texture dictionary. Represents the amplitude modulation function. Represents harmonic frequency parameters. Represents the phase parameter. Represents the amplitude coefficient of a random function. Represents a random function; The particulate impact layer is used to characterize the localized impact and vibration sensations caused by sand, gravel, or granular road surfaces. The dictionary basis functions of the particulate impact layer are expressed using locally damped oscillating basis functions: in, Represents the basis functions of the particle impact dictionary. Indicates the attenuation parameter. Represents harmonic frequency parameters. Indicates the phase parameter; The discrete event layer is used to characterize road surface events such as joints, manhole covers, speed bumps, edge steps, and short-term sudden events. The single-peak pulse is represented as a basis function in the discrete event dictionary as follows: in, Represents the dictionary basis functions for discrete events. This parameter represents the duration of a single-peak pulse.

6. The method for establishing road feel in a steer-by-wire system for guiding driver takeover as described in claim 1, characterized in that, When entering the homing control mode, the parameters of the unified model are expressed as follows: in, Indicates the reference angle of the road sensor motor. This indicates the target turning angle output by the return curve. Indicates equivalent stiffness. Indicates the stiffness when returning to center. Indicates equivalent damping, Indicates the damping during the return to center position. This represents the simulated friction torque. This indicates friction compensation during the return-to-center process.

7. The method for establishing road feel in a steer-by-wire system for guiding driver takeover as described in claim 1, characterized in that, The expression for the degree of human-machine conflict is as follows: in, Indicates the degree of human-machine conflict. Indicates the current rotation angle of the road sensor motor. This indicates a cornering command from the autonomous driving system. Indicates the normalization benchmark for corner conflict. This indicates the current angular velocity of the road sensor motor. This indicates the angular velocity command for the autonomous driving system. Indicates the normalized reference for angular velocity; The expression for the vehicle stability envelope margin is as follows: in, Indicates the vehicle stability envelope margin. Indicates yaw rate. This indicates the lateral displacement deviation. and These represent the safety boundaries for yaw rate and lateral displacement deviation, respectively.

8. The method for establishing road feel in a steer-by-wire system for guiding driver takeover as described in claim 1, characterized in that, The expression for the transition weights of the unified model parameters in the initial stage of takeover is as follows: in, This indicates the transition weights for the unified model parameters during the initial stage of takeover. Indicating the driver's intention to take over, Indicates the degree of human-machine conflict. Indicates the vehicle stability envelope margin; In the initial stage of takeover, the parameter changes of the unified control model are represented as follows: in, Indicates equivalent stiffness. This represents the equivalent stiffness at the previous moment. This represents the equivalent stiffness when the driver is driving independently. Indicates equivalent damping, This indicates the equivalent damping at the previous moment. This represents the equivalent damping when the driver is driving independently. This represents the simulated friction torque. This represents the simulated friction torque at the previous moment. This represents the simulated friction torque when the driver is driving independently. Indicates the reference angle of the road sensor motor. This indicates the reference angle of the road sensor motor at the previous moment. , , , Represents equivalent stiffness initial value, This represents the stiffness during autonomous driving angle tracking. Indicates equivalent damping initial value, This indicates the damping during autonomous driving angle following. Indicates simulated friction torque The initial value.

9. The method for establishing road feel in a steer-by-wire system for guiding driver takeover as described in claim 1, characterized in that, The expression for the transition weights of the unified model parameters during the takeover transition phase is as follows: in, This indicates the transition weights of the unified model parameters during the takeover transition phase. Indicating the driver's intention to take over, Indicates the degree of human-machine conflict. Indicates the vehicle stability envelope margin; During the takeover transition phase, the parameter changes of the unified control model are represented as follows: in, Indicates equivalent stiffness. This represents the equivalent stiffness at the previous moment. This represents the equivalent stiffness when the driver is driving independently. Indicates equivalent damping, This indicates the equivalent damping at the previous moment. This represents the equivalent damping when the driver is driving independently. This indicates the compensatory damping associated with the transition phase and conflict. This represents the simulated friction torque. This represents the simulated friction torque at the previous moment. This represents the simulated friction torque when the driver is driving independently. Indicates the reference angle of the road sensor motor. This indicates the reference rotation angle of the road sensor motor at the previous moment; The expression for the transition weights of the unified model parameters during the takeover completion phase is as follows: in, This indicates the transition weights of the unified model parameters during the takeover completion phase. Indicating the driver's intention to take over, Indicates the vehicle stability envelope margin; During the takeover completion phase, the parameter changes of the unified control model are represented as follows: in, Indicates equivalent stiffness. This represents the equivalent stiffness when the driver is driving independently. Indicates protective stiffness. Indicates equivalent damping, This represents the equivalent damping when the driver is driving independently. Indicates protective damping. This represents the simulated friction torque. Indicates protective friction torque. This indicates the reference rotation angle of the road sensor motor.

10. A road feel establishment system for a steer-by-wire system oriented towards guiding driver takeover, used to execute the road feel establishment method for a steer-by-wire system according to any one of claims 1-9, characterized in that, include: The security processing module is used to collect data, store the data in the memory, and perform fault judgment based on the collected data. If a fault occurs, it enters the security degradation stage and ends the process; otherwise, it enters the second processing module. The autonomous driving status acquisition module is used to determine whether the autonomous driving function is active under fault-free conditions. The grip detection module is used to calculate the strength of the driver's intent to take over, whereby the intent to take over is... This indicates that the driver was not holding the steering wheel and did not intend to take over. This indicates that the driver is holding the steering wheel; The mode determination module is used to generate a target steering wheel angle based on the autonomous driving steering command when the autonomous driving function is activated and the driver is not involved in the control, so that the steering wheel can track it. The road feel simulation module is used to enter the driver-independent driving mode when the autonomous driving function is not activated and the driver is holding the steering wheel. It uses a unified control model to simulate road feel and a dictionary basis function model to simulate road surface unevenness excitation. The return-to-center control module is used to enter the return-to-center control mode when the autonomous driving function is not activated and the driver is not holding the steering wheel. It uses a unified control model to perform angle control according to a predetermined return-to-center curve with the steering wheel center position or the target return-to-center position as the target, and generates return-to-center torque based on the angle error. The parameter adjustment module is used to guide the driver to take over when the autonomous driving function is activated and the driver is holding the steering wheel and entering the driver takeover mode. In the driver takeover mode, the road sense simulation motor guides the driver to complete the takeover by adjusting the unified control model parameters based on the degree of human-machine conflict and the vehicle stability envelope margin. Specifically, in the initial stage of takeover, the transition weights of the unified model parameters in the initial stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; in the transition stage of takeover, the transition weights of the unified model parameters in the transition stage of takeover are defined based on the degree of human-machine conflict and the vehicle stability envelope margin; and in the completion stage of takeover, the transition weights of the unified model parameters in the completion stage of takeover are defined based on the vehicle stability envelope margin. The limit simulation module is used to disengage autonomous driving after the driver takes over. When the driver manipulates the steering wheel beyond the preset limit angle, the limit feel is generated by increasing the equivalent stiffness and equivalent damping in the unified control model. When the driver returns to the preset angle range, the road feel simulation equivalent stiffness and equivalent damping are restored. The execution control module is used to output torque commands for the automatic driving mode, driver takeover mode, driver independent driving mode, return to center mode, and limit simulation to the road feel simulation motor, execute control, and complete the road feel establishment for the steer-by-wire system. Among them, the driver independent driving mode and return to center mode indicate that the driver has taken over the control.

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