Vehicle steering system imbalance compensation method and imbalance compensation system

Abstract

Disclosed are a vehicle steering system imbalance compensation method and imbalance compensation system. The method comprises: normalization processing (S1), performing a 90-degree phase shift on the basis of a wheel speed frequency signal of a vehicle, to obtain a quadrature wheel speed frequency signal array; adaptive processing (S2), performing adaptive filtering on the basis of the wheel speed frequency signal array and a steering wheel torque, to obtain an adaptive output signal; and phase compensation processing (S3), performing phase compensation processing on the basis of the adaptive output signal and the wheel speed frequency signal, to obtain an imbalance compensation output signal, so as to compensate for the imbalance of a vehicle steering system. In the method, by means of the normalization processing, a direct current component of a signal can be effectively filtered out, such that a compensation torque remains stable and is not prone to divergence; and by introducing the steering wheel torque as an error signal input for adaptive control, the compensation torque can be calculated in real time, thereby effectively reducing the steering wheel oscillation.

Description

Unbalance compensation methods and unbalance compensation systems for vehicle steering systems

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411011101.9, filed on July 26, 2024, entitled “Unbalance Compensation Method and Unbalance Compensation System for Vehicle Steering System”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of steering control technology, and in particular to an imbalance compensation method and an imbalance compensation system for a vehicle steering system. Background Technology

[0004] During driving, vehicles may encounter situations such as uneven road surfaces or other factors causing impacts, uneven tire wear, incorrect tire dynamic balance, and high-speed braking. Road excitation will be amplified by the suspension and steering system within a fixed frequency range and transmitted to the response end—the steering wheel, causing steering wheel vibration and discomfort to the driver, affecting the driving experience and driving safety.

[0005] In related technologies, many solutions aim to reduce steering wheel shimmy by designing high-damping bushings to absorb wheel vibrations and altering the natural frequencies of resonant system components. However, after prolonged vehicle use, steering wheel shimmy may recur due to bushing aging. Other solutions involve torque compensation from the electronic power steering (EPS) system; however, this method calculates the torque fluctuation frequency based on vehicle speed and then compensates accordingly. This approach lacks adaptive compensation and exhibits poor robustness. Summary of the Invention

[0006] To overcome the problems existing in related technologies, the present invention provides an imbalance compensation method and an imbalance compensation system for a vehicle steering system.

[0007] According to a first aspect of the present invention, the present invention provides an imbalance compensation method for a vehicle steering system, comprising:

[0008] Normalization processing is performed, and a 90-degree phase shift is applied to the vehicle's wheel speed frequency signal to obtain an orthogonal wheel speed frequency signal array.

[0009] Adaptive processing involves performing adaptive filtering based on the wheel speed frequency signal array and steering wheel torque to obtain an adaptive output signal; and

[0010] Phase compensation processing is performed based on the adaptive output signal and the wheel speed frequency signal to obtain an imbalance compensation output signal, which is used to compensate for the imbalance of the vehicle steering system.

[0011] In some embodiments, the normalization process further includes: first performing low-pass filtering on the wheel speed frequency signal, and then performing a 90-degree phase shift on the wheel speed frequency signal to obtain an orthogonal wheel speed frequency signal array.

[0012] In some embodiments, the normalization process further includes: performing low-pass filtering on the left wheel speed frequency signal and the right wheel speed frequency signal of the vehicle to obtain an average wheel speed frequency; performing a 90-degree phase shift based on the left wheel speed frequency signal and the average wheel speed frequency to obtain an orthogonal left wheel speed frequency signal array; and performing a 90-degree phase shift based on the right wheel speed frequency signal and the average wheel speed frequency to obtain an orthogonal right wheel speed frequency signal array.

[0013] In some embodiments, the adaptive processing further includes: obtaining an adaptive output signal based on the wheel speed frequency signal array and through filter parameters; obtaining an error signal between the adaptive output signal and the desired signal based on the steering wheel torque; and adjusting the adaptive output signal by adjusting the filter parameters to reduce the error signal.

[0014] In some embodiments, the adaptive output signal adjusts the filter parameters at the current moment based on the filter parameters obtained at the previous moment.

[0015] In some embodiments, a left-wheel adaptive output signal is obtained based on a left-wheel speed frequency signal array and through filter parameters; a right-wheel adaptive output signal is obtained based on a right-wheel speed frequency signal array and through filter parameters; and the adaptive output signal is obtained by calculating the average value of the left-wheel adaptive output signal and the right-wheel adaptive output signal.

[0016] In some embodiments, the imbalance compensation method further includes: controlling a compensation motor through the imbalance compensation output signal, and compensating for the imbalance of the vehicle steering system through the compensation motor.

[0017] According to a second aspect of the present invention, an imbalance compensation system is provided, comprising: a normalization module, an adaptive module, and a phase compensation module. The normalization module is configured to perform a 90-degree phase shift based on the vehicle's wheel speed frequency signals to obtain an orthogonal array of wheel speed frequency signals; the adaptive module is configured to perform adaptive filtering based on the wheel speed frequency signal array and steering wheel torque to obtain an adaptive output signal; and the phase compensation module is configured to perform phase compensation based on the adaptive output signal and the wheel speed frequency signals to obtain an imbalance compensation output signal, thereby compensating for imbalances in the vehicle's steering system.

[0018] In some embodiments, the normalization module includes an input module configured to perform low-pass filtering on the wheel speed frequency signal before performing a 90-degree phase shift on the wheel speed frequency signal.

[0019] In some embodiments, the adaptive module is further configured to: obtain an adaptive output signal based on the wheel speed frequency signal array and through filter parameters; obtain an error signal between the adaptive output signal and the desired signal based on the steering wheel torque; and adjust the adaptive output signal by adjusting the filter parameters to reduce the error signal.

[0020] The imbalance compensation method and system provided by the embodiments of this invention introduce real-time collected steering wheel torque as the error signal input to the adaptive module, calculates the compensation torque in real time, and performs closed-loop torque compensation to adapt to different working conditions. This effectively reduces the imbalance caused by steering wheel sway and improves the robustness of the system. Through normalization processing, a 90-degree phase shift can be achieved in the wheel speed frequency signal. During adaptive weighted calculation, due to the orthogonality of the signals, abnormal accumulation calculation of compensation torque will not be caused by changes in normal steering wheel torque, thus improving the accuracy of torque compensation. In addition, by performing low-pass filtering on the wheel speed frequency signal through the input module, noise can be filtered out, thereby further improving the accuracy of torque compensation in the imbalance compensation system. This method can achieve phase and amplitude control of the compensation torque of the imbalance compensation system by setting control zero point, pole, and allowable threshold for steering wheel torque fluctuation, resulting in better accuracy and responsiveness. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 shows a flowchart of an imbalance compensation method according to some embodiments;

[0023] Figure 2 illustrates a schematic diagram of the workflow of the input module according to some embodiments;

[0024] Figure 3 illustrates a flowchart of the normalization module according to some embodiments;

[0025] Figure 4 illustrates a schematic diagram of the workflow of an adaptive module according to some embodiments;

[0026] Figure 5 shows a schematic diagram of the adaptive algorithm of the adaptive module according to some embodiments;

[0027] Figure 6 illustrates a schematic diagram of the operation of a phase compensation module according to some embodiments;

[0028] Figure 7 shows a structural block diagram of an imbalance compensation system according to some embodiments; and

[0029] Figure 8 shows a structural block diagram of an imbalance compensation system according to some embodiments. Detailed Implementation

[0030] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0031] During vehicle operation, vehicles may encounter situations such as impacts caused by uneven road surfaces or other factors, uneven tire wear, incorrect tire dynamic balance, and high-speed braking. Road surface excitation is amplified by the suspension and steering system within a fixed frequency range and transmitted to the response end—the steering wheel. In order to improve the driver's comfort and operability in controlling the steering wheel, this invention provides an imbalance compensation method for vehicle steering systems.

[0032] The imbalance compensation method is applied to an imbalance compensation system. Figure 1 shows a flowchart of an imbalance compensation method according to some embodiments. Referring to Figure 1, the imbalance compensation method includes:

[0033] S1: Normalization processing, based on the vehicle's wheel speed frequency signal, performs a 90-degree phase shift to obtain an orthogonal wheel speed frequency signal array.

[0034] S2: Adaptive processing, performing adaptive filtering based on the wheel speed frequency signal array and steering wheel torque to obtain an adaptive output signal; and

[0035] S3: Phase compensation processing: Based on the adaptive output signal and the wheel speed frequency signal, phase compensation processing is performed to obtain an imbalance compensation output signal to compensate for the imbalance of the vehicle steering system.

[0036] Specifically, the imbalance compensation system includes a normalization module, an adaptive module, and a phase compensation module, each used to execute a step of the imbalance compensation method. Figure 2 shows a schematic diagram of the input module's workflow according to some embodiments; Figure 3 shows a schematic diagram of the normalization module's workflow according to some embodiments; Figure 4 shows a schematic diagram of the adaptive module's workflow according to some embodiments; Figure 5 shows a schematic diagram of the adaptive algorithm of the adaptive module according to some embodiments; and Figure 6 shows a schematic diagram of the phase compensation module's workflow according to some embodiments.

[0037] In some optional embodiments, the normalization process further includes: first performing low-pass filtering on the wheel speed frequency signal, and then performing a 90-degree phase shift on the wheel speed frequency signal to obtain an orthogonal wheel speed frequency signal array.

[0038] Referring to Figures 2 and 3, the normalization module 1 is used to perform the normalization processing step. The normalization module 1 includes an input module 11. Specifically, a wheel speed frequency signal is acquired using a speed sensor; the input module 11 is equipped with a low-pass filter to perform low-pass filtering on the acquired wheel speed frequency signal to filter out noise and reduce interference from impurities and noise on the wheel speed frequency signal.

[0039] Furthermore, as shown in Figure 2, the left wheel speed frequency signal and the right wheel speed frequency signal can be collected from the left wheel and the right wheel of the vehicle respectively. The left wheel speed frequency signal and the right wheel speed frequency signal are low-pass filtered by the input module 11. Then, the average value of the left wheel speed frequency signal and the right wheel speed frequency signal after low-pass filtering is calculated to obtain the average wheel speed frequency.

[0040] In some optional embodiments, referring to Figure 3, the normalization process in the normalization module 1 further includes: performing a 90-degree phase shift based on the left wheel speed frequency signal and the average wheel speed frequency to obtain an orthogonal left wheel speed frequency signal array; and performing a 90-degree phase shift based on the right wheel speed frequency signal and the average wheel speed frequency to obtain an orthogonal right wheel speed frequency signal array.

[0041] Specifically, the transfer function for signal processing in the discrete domain is given by Equation 1:

[0042] Where x is the wheel speed frequency signal acquired by the speed sensor, Y1 is the wheel speed frequency signal array, Z is the discrete domain, and A1 and A2 are adjustable parameters. Thus, the left wheel speed frequency signal array and the right wheel speed frequency signal array can be obtained by substituting the acquired left wheel speed frequency signal and right wheel speed frequency signal into Formula 1 respectively.

[0043] Parameter A1 can be obtained by adjusting the average wheel speed frequency, sampling period, and amplitude. Parameter A1 affects the frequency signal bandwidth, decreasing as the frequency increases. The higher the wheel speed frequency, the smaller parameter A1, resulting in better filtering. Therefore, a certain wheel speed frequency is usually required to achieve a good filtering effect. Experiments show that the wheel speed frequency typically needs to be within the operating range of 8-20Hz, with a 90-degree phase difference between the output and input signals. This indicates that the filter in normalization module 1 can perform error-free tracking and phase shifting of a given frequency AC signal and can completely filter out the DC component. Parameter A2 ranges from 0 to 1, with values ​​closer to 1 indicating better filtering performance.

[0044] By normalizing the left and right wheel speed frequency signals and introducing adjustable parameters, the DC component is attenuated more significantly, thereby eliminating computational interference caused by the DC component in the original signal. At the same time, a 90-degree phase shift of the signal is achieved, resulting in two orthogonal signals that can be used as inputs for subsequent compensation calculations.

[0045] In some optional embodiments, referring to Figures 4 and 5, the adaptive module 2 is used to perform the adaptive processing steps, which further include:

[0046] Based on the wheel speed frequency signal array, an adaptive output signal is obtained through filter parameters;

[0047] The error signal between the adaptive output signal and the desired signal is obtained based on the steering wheel torque.

[0048] The adaptive output signal is adjusted by regulating the filter parameters to reduce the error signal.

[0049] Specifically, the steering wheel torque can be acquired by a TAS sensor. In this technical solution, fluctuations in the steering wheel torque are compensated for. During compensation, the fluctuations felt by the driver when operating the steering wheel are reduced. Therefore, the steering wheel torque value acquired by the TAS sensor is used as an error signal to calculate adjustable parameters.

[0050] The weight coefficient vector is expressed as Formula 2: W (n+1) =W(n) +2μT q Y 1(n)

[0051] Among them, T q T is the steering wheel torque value read by the TAS sensor in the current calculation cycle. q =e(n), where e(n) is the error signal and n is the number of taps in the filter.

[0052] The adaptive output signal adjusts the filter parameters at the current time based on the filter parameters obtained at the previous time step, thus the adaptive output signal Y... 2(n) Represented as Formula 3:

[0053] Referring to Figure 5, the input signal, namely the wheel speed frequency signal array Y1 obtained by Formula 1, is filtered by the parameter-adjustable adaptive module 2 to generate an adaptive output signal Y2. This output signal Y2 is compared with the desired signal D(n) to form an error signal e(n). The adjustable parameters of the filter are adjusted by the adaptive algorithm to minimize the mean square value of e(n).

[0054] The filter in adaptive module 2 can automatically adjust the adjustable parameters of the filter at the current moment by using the results of the filter parameters obtained at the previous moment, so as to adapt to the characteristics of the signal changing over time, thereby achieving optimal filtering.

[0055] Since the steering wheel torque signal collected by the TAS sensor and the wheel speed frequency signal collected by the speed sensor are orthogonal signals, the steering wheel torque fluctuation caused by imbalance at the non-wheel end will not cause the calculation divergence of this technical solution. That is, when the stable steering wheel torque signal and the wheel speed frequency signal are inconsistent, the calculation compensation torque of this solution can converge to near 0 because the signals are orthogonal.

[0056] In some optional embodiments, referring to Figure 5, the adaptive output signal of the left wheel is obtained based on the left wheel speed frequency signal array and through filter parameters; the adaptive output signal of the right wheel is obtained based on the right wheel speed frequency signal array and through filter parameters; the adaptive output signal is obtained by calculating the average value of the adaptive output signal of the left wheel and the adaptive output signal of the right wheel.

[0057] Referring to Figure 6, the phase compensation module 3 is used to perform phase compensation processing. Based on the adaptive output signal and the wheel speed frequency signal, phase compensation processing is performed to obtain an imbalance compensation output signal, which is used to compensate for the imbalance in the vehicle steering system. The specific calculation process is as follows.

[0058] Based on the average wheel speed frequency signal obtained from input module 11, the corresponding maximum compensation setting angle θ and center frequency ω can be obtained by looking up a table. m Represented as Formula 4: ω m =2πY1T s

[0059] Among them, T s The sampling period is the period of the unbalanced compensation system.

[0060] The calculation process for the zeros, poles, and adjustment coefficients of the discrete compensation function is as follows:

[0061] After discretization, the zeros, poles, and adjustment coefficients of the discrete compensation function are expressed as follows:

[0062] Equation 5-7:

[0063] Therefore, the unbalanced compensation output signal Y3 is expressed as Equation 8: Y3=b0kY2-Y2 -1 *Z m *k*b0+y -1 *p k

[0064] Due to factors such as the mechanical transmission of the imbalance compensation system, the torque signal and wheel speed signal of the TAS sensor have a certain phase delay. By adding a phase compensation module, phase compensation is performed for different wheel speed frequency signals, so that the compensation torque and the phase of the wheel end swing are consistent.

[0065] In some optional embodiments, the imbalance compensation method further includes: controlling a compensation motor through the imbalance compensation output signal, and compensating for the imbalance of the vehicle steering system through the compensation motor.

[0066] On the other hand, the present invention also provides an imbalance compensation system. Figure 7 shows a structural block diagram of an imbalance compensation system according to some embodiments. As shown in Figure 7, the imbalance compensation system includes: a normalization module 1, an adaptive module 2, and a phase compensation module 3. The normalization module 1 is configured to perform a 90-degree phase shift based on the vehicle's wheel speed frequency signal to obtain an orthogonal wheel speed frequency signal array; the adaptive module 2 is configured to perform adaptive filtering based on the wheel speed frequency signal array and steering wheel torque to obtain an adaptive output signal; and the phase compensation module 3 is configured to perform phase compensation based on the adaptive output signal and the wheel speed frequency signal to obtain an imbalance compensation output signal, thereby compensating for the imbalance of the vehicle steering system.

[0067] In some embodiments, the normalization module 1 includes an input module 11, which is configured to perform low-pass filtering on the wheel speed frequency signal before performing a 90-degree phase shift on the wheel speed frequency signal.

[0068] Specifically, the wheel speed frequency signal is acquired by a speed sensor; the input module 11 is equipped with a low-pass filter to perform low-pass filtering on the acquired wheel speed frequency signal to filter out noise and reduce interference from impurities and noise on the wheel speed frequency signal; then, the wheel speed frequency signal is phase-shifted by 90 degrees by the normalization module 1.

[0069] In some embodiments, the adaptive module 2 is further configured to: obtain an adaptive output signal based on the wheel speed frequency signal array and through filter parameters; obtain an error signal between the adaptive output signal and the desired signal based on the steering wheel torque; and adjust the adaptive output signal by adjusting the filter parameters to reduce the error signal.

[0070] The steering wheel torque can be acquired by a TAS sensor. The steering wheel torque value acquired by the TAS sensor can be used as an error signal to calculate adjustable parameters, and an imbalance compensation output signal can be obtained through the aforementioned method to compensate for the imbalance of the vehicle steering system.

[0071] The imbalance compensation system can perform the imbalance compensation method as described in any of the foregoing embodiments, and its effects are as described above, and will not be repeated here.

[0072] In another aspect, the present invention also provides an imbalance compensation system. Figure 8 shows a structural block diagram of an imbalance compensation system according to some embodiments. The imbalance compensation system includes: a sampling module 100, a data processing module 200, and an execution module 300. The sampling module 100 is configured to collect wheel speed frequencies and steering wheel torque; the data processing module 200 is configured to obtain an imbalance compensation output signal based on the wheel speed frequencies and steering wheel torque collected by the sampling module 100 using an imbalance compensation method as described in any of the foregoing embodiments; and the execution module 300 is configured to compensate for the imbalance of the vehicle steering system based on the imbalance compensation output signal.

[0073] In some embodiments, the sampling module 100 includes a speed sensor and a TAS sensor; the execution module 300 includes a compensation motor, which is disposed on the wheel side or steering wheel side of the vehicle steering system, and compensates for the imbalance of the vehicle steering system through the compensation motor.

[0074] The imbalance compensation system can perform the imbalance compensation method as described in any of the foregoing embodiments, and its effects are as described above, and will not be repeated here.

[0075] The imbalance compensation method and system provided by the embodiments of this invention introduce real-time collected steering wheel torque as the error signal input to the adaptive module, calculates the compensation torque in real time, and performs closed-loop torque compensation to adapt to different working conditions. This effectively reduces the imbalance caused by steering wheel sway and improves the robustness of the system. Through normalization processing, a 90-degree phase shift can be achieved in the wheel speed frequency signal. During adaptive weighted calculation, due to the orthogonality of the signals, abnormal accumulation calculation of compensation torque will not be caused by changes in normal steering wheel torque, thus improving the accuracy of torque compensation. In addition, by performing low-pass filtering on the wheel speed frequency signal through the input module, noise can be filtered out, thereby further improving the accuracy of torque compensation in the imbalance compensation system. This method can achieve phase and amplitude control of the compensation torque of the imbalance compensation system by setting control zero point, pole, and allowable threshold for steering wheel torque fluctuation, resulting in better accuracy and responsiveness.

[0076] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0077] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method of imbalance compensation for a vehicle steering system, characterized by, The method comprises: normalization processing, based on the wheel speed frequency signals of the vehicle, to obtain a quadrature wheel speed frequency signal array by 90-degree phase shift; adaptive processing, based on the wheel speed frequency signal array and the steering wheel hand torque, to obtain an adaptive output signal by adaptive filter processing; and phase compensation processing, based on the adaptive output signal and the wheel speed frequency signals, to obtain an unbalance compensation output signal to compensate for the unbalance of the vehicle steering system.

2. The imbalance compensation method according to claim 1, characterized in that, The normalization processing further comprises: low-pass filter processing on the wheel speed frequency signals, and then 90-degree phase shift on the wheel speed frequency signals to obtain a quadrature wheel speed frequency signal array.

3. The imbalance compensation method according to claim 2, characterized in that, The normalization processing further comprises: low-pass filter processing on the left wheel speed frequency signals and the right wheel speed frequency signals of the vehicle, and obtaining an average wheel speed frequency; 90-degree phase shift on the left wheel speed frequency signals and the average wheel speed frequency to obtain a quadrature left wheel speed frequency signal array; 90-degree phase shift on the right wheel speed frequency signals and the average wheel speed frequency to obtain a quadrature right wheel speed frequency signal array.

4. The imbalance compensation method according to claim 1, characterized in that, The adaptive processing further comprises: obtaining an adaptive output signal based on the wheel speed frequency signal array and filter parameters; obtaining an error signal between the adaptive output signal and an expected signal based on the steering wheel hand torque; adjusting the adaptive output signal by adjusting the filter parameters to reduce the error signal.

5. The imbalance compensation method according to claim 4, characterized in that, The adaptive output signal adjusts the filter parameters at the current time by the results of the filter parameters at the previous time.

6. The imbalance compensation method according to claim 4, characterized in that, Obtaining a left wheel adaptive output signal based on the left wheel speed frequency signal array and filter parameters, and obtaining a right wheel adaptive output signal based on the right wheel speed frequency signal array and filter parameters; and obtaining the adaptive output signal by calculating the average of the left wheel adaptive output signal and the right wheel adaptive output signal.

7. The imbalance compensation method according to claim 1, characterized in that, Further comprising: controlling a compensation motor by the unbalance compensation output signal, and compensating for the unbalance of the vehicle steering system by the compensation motor.

8. A system for compensating for unbalance, characterized in that The method comprises: a normalization module (1) configured to obtain a quadrature wheel speed frequency signal array by 90-degree phase shift based on the wheel speed frequency signals of the vehicle; an adaptive module (2) configured to obtain an adaptive output signal by adaptive filter processing based on the wheel speed frequency signal array and the steering wheel hand torque; and a phase compensation module (3) configured to obtain an unbalance compensation output signal to compensate for the unbalance of the vehicle steering system by phase compensation processing based on the adaptive output signal and the wheel speed frequency signals.

9. The imbalance compensation system of claim 8, wherein, The normalization module (1) comprises an input module (11) configured to perform low-pass filter processing on the wheel speed frequency signals before 90-degree phase shift on the wheel speed frequency signals.

10. The imbalance compensation method according to claim 8, characterized by, The adaptive module (2) is further configured to: obtain an adaptive output signal based on the wheel speed frequency signal array and filter parameters; an error signal between the adaptive output signal and a desired signal based on the steering wheel hand torque; adjusting the adaptive output signal by adjusting the filter parameters to reduce the error signal.

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