Road feeling feedback torque control method based on steer-by-wire

Abstract

The invention discloses a road feel feedback torque control method based on steer-by-wire. The method comprises the following steps: S1, establishing a feedback torque designer based on a model; s2, acquiring a reference feedback torque through a feedback torque designer; s3, taking an error value obtained by subtracting the reference feedback torque from the real feedback torque as a state quantity; s4, a high-order all-drive system is established for a steering dynamics system, torque tracking controller control processing is conducted, personalized steering feeling is achieved through main torque and compensation torque, an HOFA method is used for converting an actual nonlinear SbW system into a linear all-drive system, the design of the controller is simplified, and a high-order all-drive system controller is used for controlling the steering dynamics system. The high-precision tracking control of the steering feedback torque is realized, and the real-time performance of the system is improved. The steering-by-wire based road feeling feedback torque control method provided by the invention has the effects of eliminating nonlinearity of an actual system, improving control performance and providing accurate and real-time steering feedback for a driver.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle control algorithms, and particularly to a road feel feedback torque control method based on steer-by-wire. Background Art

[0002] With the rapid development of automotive intelligent chassis technology, the steer-by-wire (SbW) system has achieved mechanical decoupling between the steering wheel and the front tires. The steering command is transmitted through electronic signals, and the steering feedback torque cannot be directly transmitted to the driver, making it impossible for the driver to directly feel the information feedback from the road, such as vibrations caused by uneven road surfaces and friction between the wheels and the ground. Therefore, reconstructing road perception has become one of the key issues in the design of SbW systems. Existing road perception designs are mostly based on model or data-driven methods, but there are still challenges in real-time performance and control accuracy. Summary of the Invention

[0003] In view of the above problems, the present invention provides a road feel feedback torque control method based on steer-by-wire, aiming to solve the problems existing in the prior art.

[0004] The specific technical solution is as follows: A road feel feedback torque control method based on steer-by-wire includes the following steps: S1. Establish a model-based feedback torque designer; S2. Obtain a reference feedback torque through the feedback torque designer; S3. Use the error value obtained by subtracting the real feedback torque from the reference feedback torque as the state variable; S4. Establish a high-order fully actuated system for the steering dynamics system and perform torque tracking controller control processing to obtain real-time and accurate tracking of the reference feedback torque.

[0005] The above road feel feedback torque control method based on steer-by-wire further has the following characteristics. The model-based feedback torque designer includes: A main torque generation module: Generate a basic feedback torque map based on the rack feedback force and vehicle speed obtained from an extended state observer, and design a gain coefficient to correct the main torque; A compensation torque generation module: Select damping torque, friction torque, inertia torque, soft limit torque, and active return torque as compensation amounts; The damping torque is simplified to compensate for the steering wheel angular velocity with a variable damping coefficient based on vehicle speed to obtain a damping compensation torque; The friction torque uses an improved Coulomb friction model to compensate for the friction torque of the steering wheel assembly; The inertia torque is compensated by using a saturation function for limitation; Design the soft limit torque for the soft end interval, within which the soft end torque gradually increases; Design the active return torque to perform double closed-loop control of the steering wheel rotation angle and angular velocity, and perform active return gain coefficient compensation design; Reference feedback torque Calculated by the following formula: ; where is the feedback main torque, is the active return torque, is the damping torque, is the friction torque, is the inertia torque, is the soft limit torque.

[0006] The above-mentioned road feeling feedback torque control method based on steer-by-wire also has the following characteristics. The main torque generation module includes: a rack feedback force estimation unit that estimates the rack force in real time based on an extended state observer. The rack and pinion dynamics model is expressed by the following formula: ; In the formula, is the mass of the rack; is the rack damping coefficient; is the rack displacement; is the rack friction torque; is the steering resistance of the rack; is the pinion radius; is the motor reduction ratio; is the output torque of the steering motor; Generate a two-dimensional map curve based on the rack feedback force and vehicle speed, compare the estimated rack force with the vehicle speed in the current driving situation, and select the corresponding map curve to obtain the accurate rack feedback torque , and obtain the basic feedback characteristics of the steering wheel; According to the operation of the driver during turning, when the driver releases the steering wheel under the action of the active return torque, the steering wheel tends to turn to the middle, the rack force decreases, which is opposite to the sign of the active return torque. Introduce the main torque gain coefficient, and obtain it through the following formula: ; where is the absolute value of the torque measured by the torque and angle sensor, is the main torque gain dead zone node, is the absolute value of the TAS torque when the main torque gain is the maximum, is the function of the relationship between the main torque gain and the absolute value of the TAS torque based on the real vehicle calibration parameters; The main torque is calculated by the following formula: ; where is the rack feedback torque, is the main torque gain coefficient.

[0007] The above road feeling feedback torque control method based on steer-by-wire further has the following characteristics. The compensation torque generation module includes: an active return torque generation unit that generates a return torque based on the double closed-loop control of the steering wheel angle and angular velocity to ensure the quick return of the steering wheel. The active return torque is described by the following formula: Outer loop angle control: ; Inner loop angular velocity control: ; In the formula, is the desired angular velocity, and are the proportional and integral coefficients of the angle loop respectively, is the active return torque, and are the angular velocity loops respectively.

[0008] An active steering gain coefficient is introduced. When the driver actively steers, to avoid interfering with the driver's steering action, the active return torque is reduced. When the driver's hands leave the steering wheel, the active return torque assists the driver in operation. The active steering gain coefficient is described by the following formula: ; In the formula, is the dead zone node of the active return torque gain, is the absolute value of the torque at the minimum active return torque gain , is a function of the relationship between the active return torque gain based on the actual vehicle calibration parameters and the absolute value of the torque; The active return compensation torque is calculated by the following formula: ; A damping torque generation unit dynamically adjusts the steering wheel damping torque according to the vehicle speed to limit the steering wheel rotation speed. The damping torque is obtained by the following formula: ; In the formula, is the vehicle speed, is the damping coefficient that changes with the vehicle speed and increases with the increase of the speed, is the angular velocity of the handwheel rotation.

[0009] A frictional torque generation unit generates a frictional torque consistent with the steering wheel movement direction using an improved Coulomb friction model. The frictional torque is obtained by the following formula: ; In the formula, is the frictional torque, is the Coulomb frictional torque, is the gradient change coefficient; An inertia torque generation unit generates an inertia torque through the steering wheel angular acceleration to improve the steering wheel response performance. The inertia torque is described as follows: ; In the formula, is a saturation function, is the inertia coefficient; The soft end stop torque generation unit generates a non-linearly increasing torque when the steering wheel approaches the mechanical limit position to simulate a comfortable stop feeling. The soft end torque is obtained by the following formula: ; where, is the starting angle of the soft end interval, is the soft end angle, and the soft end interval angle difference , is the non-linear soft end torque, is the maximum soft end torque.

[0010] The above-mentioned road feel feedback torque control method based on steer-by-wire also has the following characteristics. In step S4, a torque tracking controller is further established. The establishment of the torque tracking controller includes the following steps: S41. Establish a steering wheel dynamics model and a road feel motor dynamics model; S42. Transform the steering wheel dynamics model established in S41 into a non-linear second-order all-wheel drive model; S43. Design a state feedback control law; S44. Construct a Lyapunov function and conduct a stability analysis.

[0011] The above-mentioned road feel feedback torque control method based on steer-by-wire also has the following characteristics. The dynamics model in step S41 includes: The steering wheel is a typical dual-input system, allowing the driver to rotate the steering wheel by adjusting the arm impedance and providing the necessary steering feedback to the driver. Assuming the steering column is rigid, the steering wheel dynamics model can be expressed as follows: ; where, is the input torque of the driver; is the moment of inertia of the steering column; is the damping coefficient; is the handwheel angle; is the Coulomb friction torque; is the torque measured by the torque and angle sensors; is expressed by the following formula: ; where, is the sensor stiffness coefficient; is the mechanical angle of the road feel motor; is the reduction ratio of the road feel motor; is the handwheel angle; The road feel motor dynamics model is expressed by the following formula: ; where, is the motor output torque; is the moment of inertia of the motor; is the motor damping coefficient; is the Coulomb friction torque of the motor.

[0012] The above road feeling feedback torque control method based on steer-by-wire also has the following characteristics. The conversion of the steering wheel dynamics equation into a non-linear second-order fully actuated model includes: The second-order state space equation is expressed by the following formula: ; where are two states of the SbW system, u = represents the control input, is considered as the measurable disturbance measured by the sensor; Combining the above, the second-order fully actuated model of the steering feedback torque system can be obtained, which is expressed by the following formula: ; where: satisfies the full actuation condition .

[0013] The above road feeling feedback torque control method based on steer-by-wire also has the following characteristics. The state feedback control law includes: Introducing form, the reference feedback torque obtained by the feedback torque designer is used as to obtain an error feedback system with respect to , which is expressed by the following formula: ; where, is the reference signal to be tracked; By adopting the parameterization method, the state feedback control law is designed, which is expressed by the following formula: ; Substituting the state feedback control law into the error feedback system, the final closed-loop system is obtained, which is expressed by the following formula: .

[0014] The above road feeling feedback torque control method based on steer-by-wire also has the following characteristics. The step S44 includes: According to the second-order fully actuated model, the Lyapunov function is selected and expressed by the following formula: ; The stability proof is carried out: V remains uniformly ultimately bounded and the closed-loop system is asymptotically stable.

[0015] In summary, the beneficial effects of this solution are: In the road feel feedback torque control method based on steer-by-wire provided by the present invention, personalized steering feelings are achieved through the main torque and the compensation torque. The HOFA method is used to transform the actual non-linear SbW system into a linear fully actuated system, simplifying the controller design. Through the high-order fully actuated system controller, high-precision tracking control of the steering feedback torque is realized, improving the real-time performance of the system. The road feel feedback torque control method based on steer-by-wire provided by the present invention has the effects of eliminating the non-linearity of the actual system, improving the control performance, and providing accurate and real-time steering feedback to the driver. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic flow chart of a road feel feedback torque control method based on steer-by-wire according to the present invention; Figure 2 is a structural block diagram of a feedback torque designer of a road feel feedback torque control method based on steer-by-wire according to the present invention; Figure 3 is a structural block diagram of a main torque generation module of a road feel feedback torque control method based on steer-by-wire according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0019] The present invention will be further described below in conjunction with specific embodiments, but it is not limited to the present invention.

[0020] Figure 1 is a schematic flow chart of a road feel feedback torque control method based on steer-by-wire according to the present invention, Figure 2 is a structural block diagram of a feedback torque designer of a road feel feedback torque control method based on steer-by-wire according to the present invention, Figure 3 is a structural block diagram of a main torque generation module of a road feel feedback torque control method based on steer-by-wire according to the present invention, as Figures 1 - 3 shown, the road feel feedback torque control method based on steer-by-wire provided in this embodiment includes the following steps: S1. Establish a model-based feedback torque designer; S2. Obtain a reference feedback torque through the feedback torque designer; S3. Use the error value obtained by subtracting the reference feedback torque from the actual feedback torque as the state variable; S4. Establish a high-order all-wheel drive system for the steering dynamics system and perform torque tracking controller control processing to obtain real-time and accurate tracking of the reference feedback torque.

[0021] In the above embodiment, the model-based feedback torque designer includes: Main torque generation module: Based on the rack feedback force and vehicle speed obtained from the extended state observer, generate a basic feedback torque map, and design a gain coefficient to correct the main torque; Compensation torque generation module: Select damping torque, friction torque, inertia torque, soft limit torque, and active return torque as compensation amounts; Simplify the damping torque to compensate for the variable damping coefficient with vehicle speed for the steering wheel angular velocity to obtain the damping compensation torque; Use an improved Coulomb friction model to compensate for the friction torque of the steering wheel assembly; Limit the compensation of the inertia torque using a saturation function; Design a soft end interval for the soft limit torque, and the soft end torque gradually increases within the interval; Design a double closed-loop control for the steering wheel rotation angle and angular velocity for the active return torque, and perform active return gain coefficient compensation design; Reference feedback torque Calculated by the following formula: ; where is the feedback main torque, is the active return torque, is the damping torque, is the friction torque, is the inertia torque, is the soft limit torque.

[0022] In the above embodiment, the main torque generation module includes: a rack feedback force estimation unit that estimates the rack force in real time based on the extended state observer. The gear-rack dynamics model is expressed by the following formula: ; In the formula, is the mass of the rack; is the rack damping coefficient; is the rack displacement; is the rack friction torque; is the steering resistance of the rack; is the pinion radius; is the motor reduction ratio; is the output torque of the steering motor; Generate a two-dimensional map curve based on the rack feedback force and vehicle speed, compare the estimated rack force with the vehicle speed in the current driving situation, and select the corresponding map curve to obtain the accurate rack feedback torque , the basic feedback characteristics of the steering wheel are obtained; according to the operating conditions of the driver during turning, when the driver releases the steering wheel under the action of the active return torque, the steering wheel tends to rotate towards the middle, the rack force decreases, which is opposite to the sign of the active return torque. The main torque gain coefficient is introduced and obtained by the following formula: ; where is the absolute value of the torque measured by the torque and angle sensor, is the main torque gain dead zone node, is the absolute value of the TAS torque when the main torque gain is the maximum, is a function of the relationship between the main torque gain and the absolute value of the TAS torque based on the vehicle calibration parameters; the main torque is calculated by the following formula: ; where is the rack feedback torque, is the main torque gain coefficient.

[0023] In the above embodiment, the compensation torque generation module includes: An active return torque generation unit that generates a return torque based on the double closed-loop control of the steering wheel angle and angular velocity to ensure the rapid return of the steering wheel. The active return torque is described by the following formula: Outer loop angle control: ; Inner loop angular velocity control: ; In the formula, is the desired angular velocity, and are the proportional and integral coefficients of the angle loop respectively, is the active return torque, and are the angular velocity loops respectively.

[0024] The active steering gain coefficient is introduced. When the driver actively steers, to avoid interfering with the driver's steering action, the active return torque is reduced. When the driver's hands leave the steering wheel, the active return torque assists the driver's operation. The active steering gain coefficient is described by the following formula: ; In the formula, is the dead zone node of the active return torque gain, is when the minimum active return torque gain the absolute value of the torque, is the active return torque gain based on the vehicle calibration parameters and the function of the relationship between the absolute value of the torque; the active return compensation torque is calculated by the following formula: ; A damping torque generation unit that dynamically adjusts the steering wheel damping torque according to the vehicle speed to limit the steering wheel rotation speed. The damping torque is obtained by the following formula: ; In the formula, is the vehicle speed, is the damping coefficient that varies with vehicle speed and increases as the speed increases. is the angular velocity of the handwheel rotation.

[0025] The frictional torque generating unit generates a frictional torque that is consistent with the steering wheel movement direction using an improved Coulomb friction model. The frictional torque is obtained through the following formula: ; where is the frictional torque, is the Coulomb frictional torque, is the gradient change coefficient; the inertial torque generating unit generates an inertial torque through the steering wheel angular acceleration to improve the steering wheel response performance. The inertial torque is described as follows: ; where is the saturation function, is the inertia coefficient; the soft end limit torque generating unit generates a non-linearly increasing torque when the steering wheel approaches the mechanical limit position to simulate a comfortable limit feeling. The soft end torque is obtained through the following formula: ; where is the starting angle of the soft end interval, is the soft end angle, and the soft end interval angle difference , is the non-linear soft end torque, is the maximum soft end torque.

[0026] In the above embodiment, step S4 further includes establishing a torque tracking controller. The establishment of the torque tracking controller includes the following steps: S41. Establish a steering wheel dynamics model and a road feel motor dynamics model; S42. Convert the steering wheel dynamics model established in S41 into a non-linear second-order all-wheel drive model; S43. Design a state feedback control law; S44. Construct a Lyapunov function and perform stability analysis.

[0027] In the above embodiment, the dynamics model in step S41 includes: The steering wheel is a typical dual-input system that allows the driver to rotate the steering wheel by adjusting the arm impedance and provides the driver with necessary steering feedback. Assuming the steering column is rigid, the steering wheel dynamics model can be expressed as follows: ; where is the input torque of the driver; is the moment of inertia of the steering column; is the damping coefficient; is the handwheel angle; is the Coulomb frictional torque; is the torque measured by the torque and angle sensor; is expressed by the following formula: ; where is the sensor stiffness coefficient; is the mechanical angle of the road feel motor; is the reduction ratio of the road feel motor; is the handwheel angle; the dynamic model of the road feel motor is expressed by the following formula: ; where is the motor output torque; is the moment of inertia of the motor; is the motor damping coefficient; is the motor Coulomb friction torque.

[0028] It should be noted that the above-mentioned road feel motor is a permanent magnet synchronous motor.

[0029] In the above embodiment, the steering wheel dynamic equation is transformed into a non-linear second-order full drive model, including: the second-order state space equation is expressed by the following formula: ; where are the two states of the SbW system, u = represents the control input, is considered as the measurable disturbance measured by the sensor; combining the above, the second-order full drive model of the steering feedback torque system can be obtained, which is expressed by the following formula: ; where, satisfies the full drive condition .

[0030] In the above embodiment, the state feedback control law includes: introduce form, and the reference feedback torque obtained by the feedback torque designer is used as to obtain an error feedback system about , which is expressed by the following formula: ; where, is the reference signal to be tracked; by adopting the parameterization method, the state feedback control law is designed, which is expressed by the following formula: ; bringing the state feedback control law into the error feedback system, the final closed-loop system is obtained, which is expressed by the following formula: .

[0031] In the above embodiment, step S44 includes: According to the second-order full drive model, select the Lyapunov function, which is expressed by the following formula: ; conduct stability proof: V remains consistent and ultimately bounded, and the closed-loop system is asymptotically stable.

[0032] Working principle: The SFT designer based on the model method and the SFT controller based on the high-order full-actuation (HOFA) system method are adopted. The SFT designer includes a main torque module and a compensation torque module obtained from the rack force-vehicle speed map. The SFT controller includes establishing an SbW system model; converting the handwheel model into a HOFA model; obtaining the error value obtained by subtracting the actual feedback torque from the total expected road feel motor torque obtained by the designer as the state quantity of the full-actuation system, conducting parametric design, and proving the stability of the closed-loop system. Compared with the prior art, the SFT designer of the present invention adopts a combination of various torque compensation factors of the steering system to provide drivers with a real, credible, and personalized steering feeling.

[0033] The above are only the preferred embodiments of the present invention, and thus do not limit the implementation manners and protection scope of the present invention. For those skilled in the art, it should be realized that all the solutions obtained by equivalent substitution and obvious changes made by using the content of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A road feel feedback torque control method based on steer-by-wire, characterized in that: The following steps are involved: S1. Establish a model-based feedback torque designer; S2. Obtaining a reference feedback torque through a feedback torque designer; S3, taking the error value obtained by subtracting the reference feedback torque from the actual feedback torque as the state quantity; S4. Establish a high-order all-wheel drive system for the steering dynamics system and perform torque tracking controller control processing to obtain real-time and accurate tracking of reference feedback torque.

2. The method for controlling torque based on road feel feedback of steer-by-wire according to claim 1, characterized in that: The model-based feedback torque designer includes: Main torque generation module: Generates basic feedback torque map based on rack feedback force and vehicle speed obtained from extended state observer, and designs gain coefficient to correct main torque; Compensation torque generation module: select damping torque, friction torque, inertia torque, soft limit torque and active return torque as compensation quantities; The damping torque is simplified to compensate the steering wheel angular velocity by a variable damping coefficient with the vehicle speed as a variable to obtain the damping compensation torque; The friction torque adopts an improved Coulomb friction model to compensate for the friction torque of the steering wheel assembly; The inertia moment is limited and compensated by using a saturation function; The soft limit torque is designed to have a soft end interval, and the soft end torque gradually increases within the interval; The active return torque is designed to perform dual closed-loop control of the steering wheel rotation angle and angular velocity, and an active return gain coefficient compensation design is performed; Reference feedback torque Calculated by the following formula: ; in, is the main feedback moment, is the active return torque, is the damping torque, is the friction torque, is the moment of inertia, is the soft limit torque.

3. The method for controlling torque based on road feel feedback of steer-by-wire according to claim 2, characterized in that: The main moment generation module includes: a rack feedback force estimation unit, which estimates the rack force in real time based on the extended state observer. The gear rack dynamics model is expressed by the following formula: ; In the formula, is the mass of the rack; is the frame damping coefficient; is the rack displacement; is the rack friction torque; is the steering resistance of the rack; is the radius of the pinion; is the motor reduction ratio; Output torque for the steering motor; Generate a two-dimensional map curve based on the rack feedback force and vehicle speed, compare the estimated rack force with the vehicle speed under the current driving conditions, and select the corresponding map curve to obtain the accurate rack feedback torque. , get the basic feedback characteristics of the steering wheel; According to the operation of the turning driver, the driver releases the steering wheel under the action of the active self-aligning torque, the steering wheel tends to turn to the middle, the rack force decreases, and the sign is opposite to the active self-aligning torque. The main torque gain coefficient is introduced and obtained by the following formula: ; in, is the absolute value of the torque measured by the torque and angle sensor, is the main torque gain dead zone node, is the absolute value of TAS torque when the main torque gain is maximum, It is a function of the relationship between the main torque gain and the absolute value of the TAS torque based on the actual vehicle calibration parameters; The main torque is calculated by the following formula: ； in, is the rack feedback torque, Main torque gain coefficient.

4. The method for controlling torque based on road feel feedback of steer-by-wire according to claim 3, characterized in that: The compensation torque generating module comprises: The active self-aligning torque generation unit generates the self-aligning torque based on the dual closed-loop control of the steering wheel angle and angular velocity to ensure that the steering wheel returns to the center quickly. The active self-aligning torque is described by the following formula: Outer ring angle control: ; Inner ring angular velocity control: ; In the formula, is the desired angular velocity, and are the proportional and integral coefficients of the angle loop, is the active return torque, and They are angular velocity loop; The active steering gain coefficient is introduced. When the driver actively steers, in order to avoid hindering the driver's steering action, the active return torque is reduced. When the driver's hands are off the steering wheel, the active return torque assists the driver's operation. The active steering gain coefficient is described by the following formula: ; In the formula, is the dead zone node of the active positive torque gain, When the minimum active return torque gain is The absolute value of the torque, The active return torque gain and Function of the relationship between the absolute values ​​of torque; The active return compensation torque is calculated by the following formula: ; The damping torque generation unit dynamically adjusts the steering wheel damping torque according to the vehicle speed to limit the steering wheel speed and damping torque. Obtained by the following formula: ; In the formula, It's the speed. is the damping coefficient that varies with vehicle speed and increases with increasing speed. is the angular velocity of the hand wheel; The friction torque generation unit uses the improved Coulomb friction model to generate the friction torque consistent with the direction of steering wheel movement. Obtained by the following formula: ; In the formula, is the friction torque, is the Coulomb friction torque, is the gradient variation coefficient; The inertia moment generation unit generates inertia moment through the steering wheel angular acceleration to improve the steering wheel response performance. The description is as follows: ; In the formula, is a saturation function, is the coefficient of inertia; The soft-end limit torque generation unit generates a nonlinear increasing torque when the steering wheel approaches the mechanical limit position to simulate a comfortable limit feeling. Obtained by the following formula: ; In the formula, is the starting angle of the soft end interval, is the soft end angle, the soft end interval angle difference , is the nonlinear soft end torque, is the maximum soft end torque.

5. The method for controlling torque based on road feel feedback of steer-by-wire according to claim 1, characterized in that: The step S4 also includes establishing a torque tracking controller, and the establishment of the torque tracking controller includes the following steps: S41, establishing a steering wheel dynamics model and a road sense motor dynamics model; S42, converting the steering wheel dynamics model established in S41 into a nonlinear second-order all-wheel drive model; S43, design state feedback control rate; S44. Construct Lyapunov function and perform stability analysis.

6. The method for controlling torque based on road feel feedback of steer-by-wire according to claim 5, characterized in that: The dynamic model in step S41 includes: the steering wheel is a typical dual-input system, which allows the driver to rotate the steering wheel by adjusting the arm impedance and provides the driver with necessary steering feedback. Assuming that the steering column is rigid, the dynamic model of the steering wheel can be expressed as follows: ; In the formula, is the driver’s input torque; is the steering column moment of inertia; is the damping coefficient; is the hand wheel angle; is the Coulomb friction torque; is the torque measured by the torque and angle sensor; It is expressed by the following formula: ； In the formula, is the sensor stiffness coefficient; is the mechanical angle of the road sensing motor; is the reduction ratio of the road-sensing motor; is the hand wheel angle; The road sense motor dynamics model is expressed by the following formula: ； In the formula, Output torque to the motor; is the motor moment of inertia; is the motor damping coefficient; is the motor Coulomb friction torque.

7. The method for controlling torque based on road feel feedback of steer-by-wire according to claim 6, characterized in that: The steering wheel dynamics equation is converted into a nonlinear second-order all-wheel drive model including: The second-order state-space equation is expressed by the following formula: ; in are the two states of the SbW system, u = represents the control input, It is considered as a measurable disturbance measured by the sensor; Combining the above, we can get the second-order full-drive model of the steering feedback torque system, which is expressed by the following formula: ; in: Meet all-wheel drive requirements .

8. The method for controlling torque based on road feel feedback of steer-by-wire according to claim 5, characterized in that: The state feedback control law includes: Introduction The reference feedback torque obtained by the feedback torque designer is As Get about The error feedback system is expressed by the following formula: ; in, To be Reference signal for tracking; By adopting the parameterization method, the state feedback control law is designed and expressed by the following formula: ； Bringing the state feedback control law to the error feedback system, we get the final closed-loop system, which is expressed by the following formula: .

9. The method for controlling torque based on road feel feedback of steer-by-wire according to claim 7, characterized in that: The step S44 comprises: According to the second-order full-drive model, the Lyapunov function is selected and expressed by the following formula: ； Proof of stability: V remains consistent and eventually bounded, and the closed-loop system is asymptotically stable.

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