An angle synchronization method, device and vehicle of a steer-by-wire system

Abstract

This invention relates to vehicle steering systems, specifically to a method, apparatus, and vehicle for steer-by-wire system angle synchronization. The method includes: in response to a steering wheel angle synchronization request, acquiring the current steering angle of the steering actuator, calculating a target steering angle based on the current steering actuator angle using a road feel simulator, and then acquiring a driver's hands-off steering wheel detection result; in response to the driver's hands-off steering wheel, performing rapid steering wheel synchronization via the road feel simulator; and in response to the driver's hands-on steering wheel, performing slow steering wheel synchronization via the road feel simulator. This method combines the driver's hands-off steering wheel detection result for synchronization, preventing steering wheel kickback and improving safety.

Description

Technical Field

[0001] This invention relates to vehicle steering systems, and more specifically to an angle synchronization method, device, and vehicle for a steer-by-wire system. Background Technology

[0002] A steer-by-wire system is a system that transmits steering commands to the steering gear via electrical signals to control vehicle steering. This system eliminates the mechanical connection between the steering wheel and the steering wheels, overcoming various limitations of traditional steering systems. This reduces the complexity of the steering system and significantly improves its responsiveness. However, because the mechanical connection is eliminated, and the limitations of traditional steering systems are completely removed, if the steering wheel is turned when the vehicle is not running, a problem arises where the steering wheel and steering wheels are out of sync.

[0003] Synchronization of actuators in a steer-by-wire system, as disclosed in patent document CN111094106A, includes a steering wheel, a feedback actuator connected to the steering wheel for providing road feedback to the driver, multiple wheels, and a steering actuator with an electric motor that operates in response to detected values ​​of various steering parameters and orients the wheels in a desired direction. The movement of the feedback actuator is synchronized with the movement of the steering actuator. The method includes the steps of: detecting rotation of the electric motor rotor caused by the movement of the wheels or the steering wheel using at least one angle sensor; recording a position change in a storage device if movement is detected; and, upon ignition, moving the feedback actuator or the steering actuator according to the stored position change to maintain synchronization between the feedback actuator and the steering actuator. Patent CN111634325A discloses a hand-grip steering wheel-wheel resynchronization system in a steer-by-wire system. This system includes a hand-grip steering wheel actuator, wheel actuators, and a resynchronization module for dynamically adjusting the hand-grip steering wheel position used for rack position reference calculations. The dynamic adjustment includes determining a loss of synchronization based on the difference between the actual hand-grip steering wheel position and the synchronized hand-grip steering wheel position. The dynamic adjustment also includes calculating the hand-grip steering wheel adjustment using the loss of synchronization, vehicle speed, and hand-grip steering wheel speed. Furthermore, the dynamic adjustment includes calculating the adjusted hand-grip steering wheel position based on the adjusted hand-grip steering wheel position and the actual hand-grip steering wheel position. Finally, the dynamic adjustment includes updating the reference rack position based on the adjusted hand-grip steering wheel position. This dynamic adjustment is repeated continuously until the hand-grip steering wheel adjustment is substantially zero.

[0004] In summary, current mainstream solutions either directly obtain the steering wheel rotation angle from the angle sensor and adjust the steering actuator accordingly (this method does not consider the instability of the vehicle's posture when adjusting the steering actuator), or directly calculate and adjust the steering wheel position based on the rack position while the vehicle is in motion. However, this still poses a dangerous situation of the steering wheel and steering wheels becoming out of sync during steering wheel rotation when the vehicle starts. Summary of the Invention

[0005] The purpose of this invention is to provide a method, device, and vehicle for synchronizing the angle of a steer-by-wire system, which can be synchronized with the results of driver hands-off steering wheel detection to avoid steering wheel slippage and improve safety.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides an angle synchronization method for a steer-by-wire system, the method comprising: in response to a steering wheel angle synchronization request, acquiring the current steering angle of a steering actuator, calculating a target steering angle based on the current steering angle of the steering actuator using a road feel simulator, and then acquiring a detection result of the driver taking off the steering wheel; in response to the driver taking off the steering wheel, performing rapid steering wheel synchronization via a road feel simulator; and in response to the driver not taking off the steering wheel, performing slow steering wheel synchronization via a road feel simulator.

[0008] Furthermore, the driver taking their hands off the steering wheel detection specifically involves: acquiring the driver's hand torque, and using the driver's hand torque as input to determine whether the driver has taken their hands off the steering wheel using the Goertzel algorithm.

[0009] Furthermore, the Goertzel algorithm for determining whether a driver has taken their hands off the steering wheel includes the following steps:

[0010] Step one: Add the input driver's hand torque to the sine wave generated by the quadrature oscillator to obtain the steering wheel torque. t is the time variable, ω is the angular frequency, representing the number of cycles the sine wave completes per second. It is the initial phase, where ω = 2πf, and f is the frequency of the sine wave;

[0011] Step 2: Preprocess the obtained steering wheel torque: Input the steering wheel torque obtained in Step 1 into the previous value array, replace the current value in the previous value array, and output the preprocessed steering wheel torque;

[0012] Step 3: According to the general recursive calculation rule, use the Goertzel algorithm to perform a discrete Fourier transform on the preprocessed steering wheel torque and calculate the amplitude-frequency value.

[0013] Step four: Divide the Fourier components obtained in step three into three parts: upper, middle, and lower. Calculate six frequencies based on the three equations: S0 = x(n) + C*S1 - S2, S2 = S1, and S1 = S0. These frequencies are denoted as: FrqDwnS0, FrqDwnS1, FrqCenS0, FrqCenS1, FrqUpS0, and FrqUpS1. Where x(n) is the input Fourier component, S0 is the first intermediate variable, S1 is the second intermediate variable, S2 is the third intermediate variable, and C is a constant.

[0014] Step 5: Demodulate the six frequencies obtained using the Goertzel algorithm to obtain the upper, middle, and lower amplitude frequency values. Add the upper, middle, and lower amplitude frequency values ​​together, normalize them, and output them in dB to obtain the detection signal.

[0015] Step 6: Compare the detection signal with a preset threshold. If the detection signal is greater than the preset threshold, it is determined that the driver has taken off the steering wheel; otherwise, it is determined that the driver has not taken off the steering wheel.

[0016] Furthermore, the driver's hand torque is obtained by estimating it based on state-space equations using steering wheel torque, steering wheel speed, steering wheel angle, and motor torque.

[0017] Furthermore, the state-space equation is:

[0018] x is the estimated system state at the current moment. Here, y represents the estimated system state for the next moment, y represents the driver's hand torque at the current moment, and u represents the input steering wheel speed, steering wheel angle, steering wheel torque, and the motor torque signal from the road feel simulator.

[0019] A is the state transition matrix.

[0020] B is the input matrix.

[0021] C is the output matrix.

[0022] D is the feed matrix.

[0023]

[0024]

[0025] J sw The moment of inertia of the steering wheel. B is the angular velocity of the steering wheel. sw This refers to the steering wheel damping coefficient. T represents the steering wheel rotation speed. tb For the torsion bar torque, T f T is the steering wheel resistance torque. d K represents the steering wheel torque. h θ is the stiffness coefficient of the steering column. sw θ is the steering wheel angle. m γ is the motor rotation angle of the road feel simulator. m The reduction ratio of the motor reducer in the road feel simulator is given by: This represents the differential damping term in the steer-by-wire system, which describes the damping force acting on the steering wheel during its movement. This represents the moment of inertia in a steer-by-wire system, describing the inertia of the steer-by-wire system during rotation.

[0026] Furthermore, the process of implementing fast or slow synchronization of the steering wheel using the road feel simulator involves: calculating the target steering wheel angle based on the target turning angle of the road feel simulator; performing a difference calculation between the current steering wheel angle and the target steering wheel angle to obtain the steering wheel angle difference; looking up the steering wheel angle difference in a table to obtain the target steering wheel speed under fast or slow synchronization; performing a difference calculation between the target steering wheel speed and the current steering wheel speed to obtain the steering wheel speed difference; and performing closed-loop control based on the steering wheel speed difference. After limit processing, the final motor assist torque of the road feel simulator is obtained, thus achieving fast or slow synchronization of the steering wheel.

[0027] Furthermore, when the driver starts the engine, a steering wheel angle synchronization request is triggered.

[0028] Secondly, the present invention provides an angle synchronization device for a steer-by-wire system, which can realize the aforementioned angle synchronization method for a steer-by-wire system, comprising: a signal processing component, which, in response to a steering wheel angle synchronization request, acquires the current steering angle of the steering actuator and calculates the target steering angle of the road feel simulator based on the current steering angle of the steering actuator; a hands-off detection component, which acquires the detection result of the driver taking their hands off the steering wheel; and a synchronization execution component, which, in response to the driver taking their hands off the steering wheel, performs rapid steering wheel synchronization through the road feel simulator; and, in response to the driver not taking their hands off the steering wheel, performs slow steering wheel synchronization through the road feel simulator.

[0029] Furthermore, the hands-off detection component includes a driver's hand torque estimation module, a sliding window acquisition module, a parameter generation module, a reset counting module, and a hands-off sign judgment module; the driver's hand torque estimation module is used to estimate the driver's hand torque based on state-space equations using steering wheel torque, steering wheel speed, steering wheel angle, and motor torque;

[0030] The sliding window acquisition module is used to acquire and calculate the Fourier components of multiple frequency points in real time; the parameter generation module is used to divide the Fourier components obtained by the sliding window acquisition module into three parts: upper, middle, and lower, and calculate six frequencies according to the three equations S0=x(n)+C*S1-S2, S2=S1, S1=S0, respectively, denoted as: FrqDwnS0, FrqDwnS1, FrqCenS0, FrqCenS1, FrqUpS0, FrqUpS1; where x(n) is the input... Fourier components, S0 is the first intermediate variable, S1 is the second intermediate variable, S2 is the third intermediate variable, and C is a constant; the reset counting module is used to demodulate the six frequencies obtained by using the Goertzel algorithm to obtain the upper, middle and lower amplitude frequency values, add the upper, middle and lower amplitude frequency values, normalize them and output them in dB to obtain the detection signal, and reset and initialize other parameters at the same time; the hands-off sign judgment module is used to compare the detection signal with the preset threshold and output the driver's hands-off steering wheel detection result.

[0031] Thirdly, the present invention provides a vehicle including the angle synchronization device of the above-described steer-by-wire system.

[0032] The beneficial effects of this invention are:

[0033] 1. The synchronization method of the present invention responds to the steering wheel angle synchronization request by obtaining the current steering actuator angle and calculating the target steering angle of the road feel simulator based on the current steering actuator angle, and combining the detection results of the driver taking off the steering wheel; responding to the driver taking off the steering wheel, the road feel simulator performs rapid steering wheel synchronization to ensure the synchronization speed; responding to the driver not taking off the steering wheel, the road feel simulator performs slow steering wheel synchronization to avoid steering wheel kicking and improve safety.

[0034] 2. This invention uses the Goertzel algorithm to determine whether the driver has taken their hands off the steering wheel, eliminating the need for an additional steering wheel capacitive sensor to detect whether the driver has taken their hands off the steering wheel, thus reducing manufacturing costs and bringing better economic benefits. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0036] Figure 1 This is a flowchart of the angle synchronization method for the steer-by-wire system described in Embodiment 1 of the present invention;

[0037] Figure 2This is a block diagram of the angle synchronization device of the steer-by-wire system described in Embodiment 2 of the present invention;

[0038] Figure 3 This is a block diagram of the hand-removal detection component described in Embodiment 2 of the present invention;

[0039] Figure 4 This is a block diagram of the driver's hand torque estimation module described in Embodiment 2 of the present invention;

[0040] Figure 5 This is a block diagram of the steering wheel-wheel synchronization module. Detailed Implementation

[0041] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0042] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0043] Example 1, see Figure 1 As shown, a method for synchronizing the angle of a steer-by-wire system includes: in response to a steering wheel angle synchronization request, obtaining the current steering angle of the steering actuator, calculating the target steering angle of the road feel simulator based on the current steering actuator angle, and then obtaining the detection result of the driver taking off the steering wheel; in response to the driver taking off the steering wheel, performing fast steering wheel synchronization through the road feel simulator; and in response to the driver not taking off the steering wheel, performing slow steering wheel synchronization through the road feel simulator.

[0044] The method described in this invention determines the synchronization mode as fast synchronization or slow synchronization based on the driver's hands-off steering wheel detection results. In response to the driver taking their hands off the steering wheel, fast synchronization is performed via a road feel simulator to ensure synchronization speed. In response to the driver not taking their hands off the steering wheel, slow synchronization is performed via the road feel simulator to prevent steering wheel jolting and improve safety. It should be noted that "fast synchronization" and "slow synchronization" are relative; that is, under the premise of the same steering wheel angle synchronization amount, the synchronization time of fast synchronization is shorter than that of slow synchronization.

[0045] In this embodiment, the driver's hands-off steering wheel detection specifically involves: acquiring the driver's hand torque, and using the driver's hand torque as input to apply the Goertzel algorithm to determine if the driver has taken their hands off the steering wheel. Specifically, applying the Goertzel algorithm to determine if the driver has taken their hands off the steering wheel includes the following steps:

[0046] Step one: Add the input driver's hand torque to the sine wave generated by the quadrature oscillator to obtain the steering wheel torque. t is the time variable, ω is the angular frequency, representing the number of cycles the sine wave completes per second. It is the initial phase, where ω = 2πf, and f is the frequency of the sine wave;

[0047] Step 2: Preprocess the obtained steering wheel torque: Input the steering wheel torque obtained in Step 1 into the previous value array, replace the current value in the previous value array, and output the preprocessed steering wheel torque;

[0048] Step 3: According to the general recursive calculation rule, use the Goertzel algorithm to perform a discrete Fourier transform on the preprocessed steering wheel torque and calculate the amplitude-frequency value.

[0049] Step four: Divide the Fourier components obtained in step three into three parts: upper, middle, and lower. Calculate six frequencies based on the three equations: S0 = x(n) + C*S1 - S2, S2 = S1, and S1 = S0. These six frequencies are denoted as: FrqDwnS0, FrqDwnS1, FrqCenS0, FrqCenS1, FrqUpS0, and FrqUpS1. Where x(n) is the input Fourier component, S0 is the first intermediate variable, S1 is the second intermediate variable, S2 is the third intermediate variable, and C is a constant.

[0050] Step 5: Demodulate the six frequencies obtained using the Goertzel algorithm to obtain the upper, middle, and lower amplitude frequency values. Add the upper, middle, and lower amplitude frequency values ​​together, normalize them, and output them in dB to obtain the detection signal.

[0051] Step 6: Compare the detection signal with a preset threshold. If the detection signal is greater than the preset threshold, it is determined that the driver has taken off the steering wheel; otherwise, it is determined that the driver has not taken off the steering wheel.

[0052] In this embodiment, the following is adopted: Figure 4 The driver hand torque estimation module shown obtains the driver hand torque by estimating it based on state-space equations using steering wheel torque, steering wheel speed, steering wheel angle, and motor torque.

[0053] The state-space equation is as follows:

[0054] x is the estimated system state at the current moment. Here, y represents the estimated system state for the next moment, y represents the driver's hand torque at the current moment, and u represents the input steering wheel speed, steering wheel angle, steering wheel torque, and the motor torque signal from the road feel simulator.

[0055] A is the state transition matrix.

[0056] B is the input matrix.

[0057] C is the output matrix.

[0058] D is the feed matrix.

[0059]

[0060]

[0061] J sw The moment of inertia of the steering wheel. B is the angular velocity of the steering wheel. sw This refers to the steering wheel damping coefficient. T represents the steering wheel rotation speed. tb For the torsion bar torque, T f T is the steering wheel resistance torque. d K represents the steering wheel torque. h θ is the stiffness coefficient of the steering column. sw θ is the steering wheel angle. m γ is the motor rotation angle of the road feel simulator. m The reduction ratio of the motor reducer in the road feel simulator is given by: This represents the differential damping term in the steer-by-wire system, which describes the damping force acting on the steering wheel during its movement. This represents the moment of inertia in a steer-by-wire system, describing the inertia of the steer-by-wire system during rotation.

[0062] In this embodiment, see Figure 5As shown, the specific steps for achieving rapid steering wheel synchronization using a road feel simulator are as follows: The target steering wheel angle is calculated from the target turning angle of the road feel simulator using the transmission ratio. The difference between the current steering wheel angle (actual steering wheel angle) and the target steering wheel angle is calculated to obtain the steering wheel angle difference. Based on this angle difference, the target steering wheel speed in rapid synchronization mode is obtained by looking up a table. The difference between the target steering wheel speed and the current steering wheel speed (actual steering wheel speed) is calculated to obtain the steering wheel speed difference. A PID control algorithm is then used for closed-loop control based on this speed difference. After limit processing, the final motor assist torque of the road feel simulator is obtained, thus achieving rapid steering wheel synchronization.

[0063] The slow-speed synchronization of the steering wheel via the road feel simulator is specifically achieved as follows: The target steering wheel angle is calculated from the target turning angle of the road feel simulator using the transmission ratio. The difference between the current steering wheel angle (actual steering wheel angle) and the target steering wheel angle is calculated to obtain the steering wheel angle difference. Based on this angle difference, the target steering wheel speed in slow-speed synchronization mode is obtained by looking up a table. The difference between the target steering wheel speed and the current steering wheel speed (actual steering wheel speed) is calculated to obtain the steering wheel speed difference. A PID control algorithm is then used for closed-loop control based on this speed difference. After limit processing, the final motor assist torque of the road feel simulator is obtained, thus achieving slow-speed synchronization of the steering wheel.

[0064] In this embodiment, when the driver starts the ignition, a steering wheel angle synchronization request is triggered, which effectively reduces the risk caused by angle asynchrony after restarting the ignition.

[0065] Example 2, see Figure 2 As shown, an angle synchronization device for a steer-by-wire system, which can realize the angle synchronization method of the steer-by-wire system described in Embodiment 1, includes: a signal processing component, which, in response to a steering wheel angle synchronization request, acquires the current steering angle of the steering actuator and calculates the target steering angle of the road feel simulator based on the current steering angle of the steering actuator; a hands-off detection component, which acquires the detection result of the driver taking their hands off the steering wheel; and a synchronization execution component, which, in response to the driver taking their hands off the steering wheel, performs rapid steering wheel synchronization through the road feel simulator; and, in response to the driver not taking their hands off the steering wheel, performs slow steering wheel synchronization through the road feel simulator.

[0066] See Figure 3 As shown, the hands-off detection component includes a driver's hand torque estimation module, a sliding window acquisition module, a parameter generation module, a reset counting module, and a hands-off sign judgment module; the driver's hand torque estimation module is used to estimate the driver's hand torque based on state-space equations using steering wheel torque, steering wheel speed, steering wheel angle, and motor torque;

[0067] The sliding window acquisition module is used to acquire and calculate the Fourier components of multiple frequency points in real time, specifically including the following steps:

[0068] 1) The steering wheel torque is obtained by adding the input driver's hand torque to the sine wave generated by the quadrature oscillator. t is the time variable, ω is the angular frequency, representing the number of cycles the sine wave completes per second. It is the initial phase, where ω = 2πf, and f is the frequency of the sine wave.

[0069] 2) Preprocess the obtained steering wheel torque: Input the steering wheel torque obtained in step one into the previous value array, replace the current value in the previous value array, and output the preprocessed steering wheel torque. That is, by operating on a previous value array, the useful part of the previous value array is treated as a loop, with 1 as the index. When entering this module, the index contains the old data in the buffer. After the new data is input, the current value is replaced and the new value is output. The output result is the preprocessed steering wheel torque.

[0070] 3) Based on the general recursive calculation rule, the Goertzel algorithm is used to perform a discrete Fourier transform on the preprocessed steering wheel torque and calculate the amplitude-frequency value; based on the general recursive calculation rule, the Goertzel algorithm is used to demodulate the signal: M = S(n). 2 +S(n-1) 2 -S(n)*S(n-1)*gain, where M is the discrete spectral component, n is the current time, S(n) and S(n-1) are the discrete signal sample values ​​at adjacent time points, and gain is the gain constant. Finally, the obtained amplitude-frequency values ​​are normalized and converted into dB values, which are then output to the next module, the parameter generation module.

[0071] The parameter generation module is used to divide the Fourier components obtained by the sliding window acquisition module into three parts: upper, middle, and lower. Based on the three equations S0=x(n)+C*S1-S2, S2=S1, and S1=S0, six frequencies are calculated and denoted as: FrqDwnS0, FrqDwnS1, FrqCenS0, FrqCenS1, FrqUpS0, and FrqUpS1, respectively. Among them, x(n) is the input Fourier component, S0 is the first intermediate variable, S1 is the second intermediate variable, S2 is the third intermediate variable, and C is a constant.

[0072] The reset counting module is used to demodulate the six frequencies obtained using the Goertzel algorithm, M = S(n). 2 +S(n-1) 2-S(n)*S(n-1)*gain, M is the discrete spectral component, n is the current time, S(n) and S(n-1) are the discrete signal sample values ​​at adjacent times, gain is the gain constant, the amplitude-frequency values ​​of the upper, middle and lower parts are obtained, the amplitude-frequency values ​​of the upper, middle and lower parts are added together, and after normalization, they are converted into the output in dB to obtain the detection signal. At the same time, other parameters are reset and initialized.

[0073] The hands-off detection module compares the detection signal with a preset threshold and outputs the result of the driver's hands-off steering wheel detection. Specifically, if the detection signal is greater than the preset threshold, it is determined that the driver has taken off the steering wheel; otherwise, it is determined that the driver has not taken off the steering wheel.

[0074] The Goertzel algorithm has the following advantages:

[0075] 1. Low computational complexity: The Goertzel algorithm has relatively low computational complexity. It only needs to perform calculations on a portion of the input signal (around a specific frequency), without processing the entire spectrum. This makes the Goertzel algorithm more advantageous when computational resources are limited or when high real-time requirements are needed.

[0076] 2. Low latency: The Goertzel algorithm is a low-latency algorithm capable of processing data in real time. Compared to mean filters, the Goertzel algorithm is faster because it focuses only on components of specific frequencies, without needing to average the entire signal.

[0077] 3. Applicable to specific frequency signals: The Goertzel algorithm is suitable for demodulating a single or a limited number of specific frequency signals, so the Goertzel algorithm is more applicable to the scenario in which this patent is applied.

[0078] 4. High-frequency analysis capability: The Goertzel algorithm focuses on extracting components at specific frequencies, making it highly effective for applications requiring accurate analysis and demodulation of signals at specific frequencies. In contrast, the mean filter used in the CN114644005A comparison file is more suitable for smoothing signals and removing noise and burst interference, but it cannot perform analysis on specific frequencies.

[0079] Example 3, see Figure 2 As shown, a vehicle includes an angle synchronization device for the steer-by-wire system described in Embodiment 2.

[0080] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A method for synchronizing the angle of a steer-by-wire system, characterized in that: In response to the steering wheel angle synchronization request, the current steering angle of the steering actuator is obtained, and the target steering angle of the road feel simulator is calculated based on the current steering angle of the steering actuator. Then, the detection result of the driver taking off the steering wheel is obtained. In response to the driver taking their hands off the steering wheel, the steering wheel is quickly synchronized via the road feel simulator; In response to the driver not taking their hands off the steering wheel, slow synchronization of the steering wheel is performed via the road feel simulator; The driver hands-off detection process specifically involves: acquiring the driver's hand torque, using the driver's hand torque as input, and employing the Goertzel algorithm to determine if the driver has taken their hands off the steering wheel. This includes the following steps: Step one: Add the input driver's hand torque to the sine wave generated by the quadrature oscillator to obtain the steering wheel torque. , t It is a time variable. It is the angular frequency, representing the number of cycles a sine wave completes per second. It is the initial phase, where , It is the frequency of a sine wave; Step 2: Preprocess the obtained steering wheel torque: Input the steering wheel torque obtained in Step 1 into the previous value array, replace the current value in the previous value array, and output the preprocessed steering wheel torque; Step 3: According to the general recursive calculation rule, use the Goertzel algorithm to perform a discrete Fourier transform on the preprocessed steering wheel torque and calculate the amplitude-frequency value. Step four: Divide the Fourier components obtained in step three into three parts: upper, middle, and lower. Calculate six frequencies based on the three equations S0=x(n)+C*S1—S2, S2=S1, and S1=S0, respectively, denoted as: FrqDwnS0, FrqDwnS1, FrqCenS0, FrqCenS1, FrqUpS0, and FrqUpS1; where x(n) is the input Fourier component, S0 is the first intermediate variable, S1 is the second intermediate variable, S2 is the third intermediate variable, and C is a constant. Step 5: Demodulate the six frequencies obtained using the Goertzel algorithm to obtain the upper, middle, and lower amplitude frequency values. Add the upper, middle, and lower amplitude frequency values ​​together, normalize them, and output them in dB to obtain the detection signal. Step 6: Compare the detection signal with a preset threshold. If the detection signal is greater than the preset threshold, it is determined that the driver has taken off the steering wheel; otherwise, it is determined that the driver has not taken off the steering wheel.

2. The angle synchronization method for the steer-by-wire system according to claim 1, characterized in that, The driver's hand torque is obtained by estimating it based on state-space equations using steering wheel torque, steering wheel speed, steering wheel angle, and motor torque.

3. The angle synchronization method for the steer-by-wire system according to claim 2, characterized in that, The state-space equation is: , This is the estimated system state at the current moment. This is the estimated system state value for the next moment. The driver's hand torque at the current moment. The input signals are the steering wheel speed, steering wheel angle, steering wheel torque, and the motor torque signal from the road feel simulator. A is the state transition matrix. ; B is the input matrix. ; C is the output matrix. ; D is the feed matrix. ; ， ； ， ， ； The moment of inertia of the steering wheel. The angular velocity of the steering wheel. This refers to the steering wheel damping coefficient. Steering wheel speed, For the torsion bar torque, Steering wheel resistance torque, Steering wheel torque, This is the steering column stiffness coefficient. For steering wheel angle, For the motor rotation angle of the road feel simulator, The reduction ratio of the motor reducer in the road feel simulator is given by: This represents the differential damping term in the steer-by-wire system, which describes the damping force acting on the steering wheel during its movement. This represents the moment of inertia in a steer-by-wire system, describing the inertia of the steer-by-wire system during rotation.

4. The angle synchronization method for the steer-by-wire system according to claim 1, characterized in that, The specific steps for implementing fast or slow synchronization of the steering wheel using a road feel simulator are as follows: The target steering wheel angle is calculated based on the target turning angle from the road feel simulator. The difference between the current steering wheel angle and the target steering wheel angle is calculated to obtain the steering wheel angle difference. Based on this angle difference, a table is consulted to obtain the target steering wheel speed for either fast or slow synchronization. The difference between the target steering wheel speed and the current steering wheel speed is calculated to obtain the steering wheel speed difference. Closed-loop control is then performed based on this speed difference. After limit processing, the final motor assist torque from the road feel simulator is obtained, thus achieving fast or slow synchronization of the steering wheel.

5. The angle synchronization method for the steer-by-wire system according to claim 1, characterized in that, When the driver starts the engine, a steering wheel angle synchronization request is triggered.

6. An angle synchronization device for a steer-by-wire system, characterized in that, The method for synchronizing the angles of the steer-by-wire system according to any one of claims 1 to 5 includes: The signal processing component, in response to the steering wheel angle synchronization request, obtains the current steering angle of the steering actuator and calculates the target steering angle of the road feel simulator based on the current steering angle of the steering actuator; The hands-off detection component is used to obtain the detection results of the driver taking their hands off the steering wheel; The synchronization execution component performs rapid steering wheel synchronization via the road feel simulator in response to the driver taking their hands off the steering wheel; and performs slow steering wheel synchronization via the road feel simulator in response to the driver not taking their hands off the steering wheel.

7. The angle synchronization device for the steer-by-wire system according to claim 6, characterized in that: The hands-off detection component includes a driver's hand torque estimation module, a sliding window acquisition module, a parameter generation module, a reset counting module, and a hands-off sign judgment module; The driver's hand torque estimation module is used to estimate the driver's hand torque based on state-space equations using steering wheel torque, steering wheel speed, steering wheel angle, and motor torque. The sliding window acquisition module is used to acquire and calculate the Fourier components of multiple frequency points in real time; The parameter generation module is used to divide the Fourier components obtained by the sliding window acquisition module into three parts: upper, middle, and lower. Based on the three equations S0=x(n)+C*S1—S2, S2=S1, S1=S0, six frequencies are calculated and denoted as: FrqDwnS0, FrqDwnS1, FrqCenS0, FrqCenS1, FrqUpS0, and FrqUpS1, respectively. Among them, x(n) is the input Fourier component, S0 is the first intermediate variable, S1 is the second intermediate variable, S2 is the third intermediate variable, and C is a constant. The reset counting module is used to demodulate the six frequencies obtained by the Goertzel algorithm, obtain the upper, middle and lower amplitude frequency values, add the upper, middle and lower amplitude frequency values, normalize them and output them in dB to obtain the detection signal, and reset and initialize other parameters at the same time. The hands-off sign detection module is used to compare the detection signal with a preset threshold and output the detection result of the driver taking his hands off the steering wheel.

8. A vehicle, characterized in that: Includes the angle synchronization device for the steer-by-wire system as described in claim 6 or 7.

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