Brake judder active suppression method and system based on wheel speed signals

Abstract

This invention discloses a method and system for actively suppressing brake vibration based on wheel speed signals. The method includes: acquiring wheel speed signals of at least one wheel; performing time-frequency analysis on the wheel speed signals to extract the first-order harmonic component synchronized with wheel rotation; estimating the current brake disc thickness difference in real time based on the amplitude of the first-order harmonic component; calculating a compensation torque using an adaptive control strategy based on the deviation between the estimated brake disc thickness difference and an acceptable threshold; and outputting the compensation torque to the brake actuator to adjust the wheel cylinder pressure of the corresponding wheel, thereby actively suppressing brake torque fluctuations. Through high-frequency wheel speed acquisition and time-frequency analysis, dynamic online calculation of the brake disc thickness difference is achieved, allowing for the identification of the root cause of brake torque fluctuations without any additional sensors. The adaptive compensation torque calculation based on the deviation can close the loop to cancel the excitation source, suppressing vibration from upstream of the propagation path and preventing vibration from being transmitted to the steering wheel and pedal.

Description

Technical Field

[0001] This invention relates to the technical field of vehicle control, specifically to a method and system for actively suppressing braking vibration based on wheel speed signals. Background Technology

[0002] Brake disc thickness variation (DTV) is one of the main causes of vehicle braking vibration. When the circumferential thickness of the brake disc is uneven, braking torque fluctuations occur during braking, which are synchronized with the wheel rotation. These fluctuations are then transmitted to the steering wheel and brake pedal through the steering system, causing perceptible vibrations that severely affect ride comfort. Existing technologies for suppressing braking vibration mainly fall into two categories: one is to control the initial DTV of the brake disc through precision machining, or to correct the existing DTV using post-processing techniques such as grinding and turning. This method is costly and cannot dynamically compensate for vibrations during vehicle use. The other approach involves adding hardware such as acceleration sensors and vibration sensors to the braking system to detect vibrations and passively reduce them. This approach increases hardware costs, and passive vibration reduction cannot eliminate braking torque fluctuations at their source. Summary of the Invention This invention aims to at least address the technical problems of high cost and inability to dynamically compensate for brake vibration during vehicle use in existing technologies. To this end, this invention provides a method and system for actively suppressing brake vibration based on wheel speed signals.

[0003] According to a first aspect of the present invention, a method for actively suppressing braking vibration based on wheel speed signals includes: Acquire the wheel speed signal of at least one wheel, wherein the sampling frequency of the wheel speed signal is not less than 2kHz; Time-frequency analysis was performed on the wheel speed signal to extract the first-order harmonic component that is synchronized with the wheel rotation; Based on the amplitude of the first harmonic component, the current brake disc thickness difference is estimated in real time; The deviation between the acceptable threshold is set, and the compensation torque is calculated by using an adaptive control strategy based on the estimated deviation between the brake disc thickness difference and the acceptable threshold. The compensation torque is output to the braking actuator to adjust the wheel cylinder pressure of the corresponding wheel and actively suppress the fluctuation of braking torque.

[0004] According to an embodiment of the present invention, a method for actively suppressing braking vibration based on wheel speed signals has at least the following beneficial effects: By acquiring high-frequency wheel speed data and performing time-frequency analysis, dynamic online calculation of brake disc thickness difference is achieved, allowing the identification of the root cause of braking torque fluctuations without the need for any additional sensors. The adaptive compensation torque calculation based on the deviation can close the loop to cancel the excitation source, suppressing jitter from the upstream of the propagation path and preventing vibration from being transmitted to the steering wheel and pedals. This method requires zero hardware modifications, is extremely low-cost, and is easy to deploy on existing ESC / brake-by-wire platforms.

[0005] According to some embodiments of the present invention, the step of performing time-frequency analysis on the wheel speed signal to extract the first-order harmonic component synchronized with the wheel rotation includes: The wheel speed signal is subjected to time-frequency transformation using short-time Fourier transform or continuous wavelet transform; Separate the first harmonic component that has the same rotational frequency as the wheel from the transformation result; Filter out non-braking excitation interference introduced by road bumps and sensor noise.

[0006] According to some embodiments of the present invention, before estimating the current brake disc thickness difference in real time based on the amplitude of the first harmonic component, the method further includes: The amplitude of the extracted first harmonic component is monitored; When the amplitude of the first harmonic component exceeds the preset vibration threshold, it is determined that braking synchronous vibration has occurred. In response to the determination, the subsequent steps of brake disc thickness difference estimation and compensation torque calculation are activated.

[0007] According to some embodiments of the present invention, the step of estimating the current brake disc thickness difference in real time based on the amplitude of the first harmonic component includes: Establish the mapping relationship between the amplitude of the first harmonic component and the thickness difference of the brake disc; Based on the amplitude of the first harmonic component at the current moment, the corresponding estimated value of the brake disc thickness difference can be obtained by looking up a table or by calculation. The output estimates the brake disc thickness difference with an accuracy of ±5μm.

[0008] According to some embodiments of the present invention, the calculation of the compensation torque using an adaptive control strategy based on the deviation between the estimated brake disc thickness difference and an acceptable threshold includes: Calculate the deviation e(k) = DTV_target DTV_estimated(k), where e(k) represents the deviation at the current time, DTV_target is the preset acceptable threshold, and DTV_estimated(k) is the estimated brake disc thickness difference at the current time; The basic compensation torque is calculated using a PID control law: ΔT(k) = Kp·e(k) + Ki·Σe(i) + Kd·[e(k)] e(k 1)], where ΔT(k) represents the compensation torque at the current moment, Kp, Ki, and Kd represent the proportional gain, integral gain, and differential gain, respectively, Σe(i) represents the cumulative sum of the deviations, and e(k 1) Indicates the deviation from the previous moment; Based on at least one of the following status information: current vehicle speed, braking pressure, and brake disc temperature, the gain values ​​of Kp, Ki, and Kd are dynamically adjusted to obtain the adaptive compensation torque.

[0009] According to some embodiments of the present invention, dynamically adjusting the gain values ​​of Kp, Ki, and Kd based on at least one state information among current vehicle speed, braking pressure, and brake disc temperature includes: A three-dimensional gain scheduling table is pre-stored, with vehicle speed, braking pressure, and brake disc temperature as index dimensions. Obtain the current vehicle speed, braking pressure, and brake disc temperature; The corresponding Kp, Ki, and Kd gain values ​​are obtained by querying the three-dimensional gain scheduling table based on the current vehicle speed, braking pressure, and brake disc temperature. When the brake disc temperature exceeds the preset high temperature threshold or the vehicle speed exceeds the preset high speed threshold, the gain values ​​of Kp, Ki, and Kd will be reduced to less than 50% of the calibrated values.

[0010] According to some embodiments of the present invention, after calculating the compensation torque using an adaptive control strategy based on the deviation between the estimated brake disc thickness difference and an acceptable threshold, the method further includes: When it is determined that the brake disc thickness difference between the left and right front axle wheels is inconsistent, the vehicle's yaw rate feedback signal is obtained. Based on the yaw rate feedback, the compensation torque output of the left and right wheels is coordinated; It generates a corrective yaw moment to maintain straight-line stability.

[0011] According to some embodiments of the present invention, before outputting the compensation torque to the braking actuator, the method further includes: Determine if the current vehicle speed is within the range of 60–140 km / h and the braking pressure is greater than 0.3 MPa; otherwise, prohibit the output of compensation torque. The compensation torque is limited to within ±15% of the total braking torque; The rate of change of the compensation torque is limited to no more than 50 N·m / s; The brake disc temperature is obtained, and when the brake disc temperature exceeds 300°C, the compensation torque output is discontinued.

[0012] According to some embodiments of the present invention, outputting the compensation torque to the braking actuator includes: The compensation torque is converted into a wheel cylinder pressure adjustment command; Send the pressure regulation command to the ESC hydraulic unit or the brake-by-wire unit.

[0013] According to a second aspect of the present invention, a vehicle brake vibration suppression system includes a processor and a memory, wherein the memory stores a computer program, and the processor executes the computer program to implement the active brake vibration suppression method described in any of the preceding claims.

[0014] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 Braking vibration active suppression system architecture diagram; Figure 2 Flowchart of the online DTV estimation algorithm; Figure 3 Compensation braking torque calculation control block diagram; Figure 4 Schematic diagram of wheel speed signal time-frequency analysis results; Figure 5 Comparison curves of steering wheel vibration acceleration before and after compensation; Figure 6 Schematic diagram of multi-round coordination control strategy; Figure 7 Adaptive gain adjustment characteristic curve; Figure 8 A flowchart of an active braking vibration suppression method based on wheel speed signals. Detailed Implementation

[0016] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0017] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0018] In the description of this invention, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features or their sequential relationship.

[0019] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0020] The following will be combined with the appendix Figures 1 to 8 The technical solution of the present invention will be clearly and completely described below. Obviously, the embodiments described below are some embodiments of the present invention, not all embodiments.

[0021] Reference Figure 8 A method for actively suppressing braking vibration based on wheel speed signals, comprising: Step S100: Acquire the wheel speed signal of at least one wheel, wherein the sampling frequency of the wheel speed signal is not less than 2kHz; Step S200: Perform time-frequency analysis on the wheel speed signal and extract the first-order harmonic component that is synchronized with the wheel rotation; Step S300: Estimate the current brake disc thickness difference in real time based on the amplitude of the first harmonic component; Step S400: Set the deviation between acceptable thresholds, and calculate the compensation torque based on the estimated deviation between the brake disc thickness difference and the acceptable thresholds using an adaptive control strategy; Step S500: Output the compensation torque to the braking actuator to adjust the wheel cylinder pressure of the corresponding wheel and actively suppress braking torque fluctuations.

[0022] Specifically, in step S100, the vehicle electronic control unit (ECU) acquires the wheel speed signal from the left front wheel speed sensor at a frequency of 2kHz. In step S200, the acquired wheel speed signal is bandpass filtered (1-100Hz) to remove high-frequency noise. Subsequently, the signal is subjected to short-time Fourier transform (STFT) or continuous wavelet transform (CWT) to perform time-frequency analysis on the wheel speed signal, extract the amplitude of the first-order harmonic component with the same frequency as the current wheel speed, and activate the algorithm after determining it as braking synchronous vibration.

[0023] Step S300: Based on the pre-calibrated amplitude-DTV mapping curve, the current brake disc thickness difference is calculated in real time to be 12μm.

[0024] Step S400: Set the acceptable threshold to 10μm and the deviation to +2μm, and use adaptive PID to calculate the compensation torque of 5N·m; Step S500: Output the compensation torque to the brake actuator (ESC) to request a 5% reduction in the pressure of the corresponding wheel cylinder to offset the braking torque fluctuation.

[0025] By acquiring high-frequency wheel speed data and performing time-frequency analysis, dynamic online calculation of brake disc thickness difference is achieved, allowing the identification of the root cause of braking torque fluctuations without the need for any additional sensors. The adaptive compensation torque calculation based on the deviation can close the loop to cancel the excitation source, suppressing jitter from the upstream of the propagation path and preventing vibration from being transmitted to the steering wheel and pedals. This method requires zero hardware modifications, is extremely low-cost, and is easy to deploy on existing ESC / brake-by-wire platforms.

[0026] Further, step S200 includes: S210: The wheel speed signal is subjected to time-frequency transformation using short-time Fourier transform, wherein the window function is Hanning window, the window length is set to 256 sampling points, the overlap rate is 50%, and the frequency resolution is 7.8125Hz (corresponding to a 2kHz sampling rate); or continuous wavelet transform is used, the wavelet basis function is Morlet wavelet, and the scale range is set to 32~128, corresponding to 0.8~1.2 times the wheel rotation frequency; S220: Extract the frequency component with the largest energy in each time window from the transformation results. If the deviation between this frequency and the current wheel rotation frequency is less than ±5%, it is determined to be a first-order harmonic component, and its amplitude is recorded. S230: A sliding median filter (window length 10ms) is used to filter out wheel speed spikes caused by road bumps, and a 50Hz notch filter and a 100Hz low-pass filter are connected in series to filter out sensor electromagnetic interference and high-frequency noise.

[0027] By using an STFT with a specified window length of 256 points and an overlap rate of 50%, a frequency resolution of 7.8Hz is obtained at a sampling rate of 2kHz, which is sufficient to distinguish between first-order and second-order harmonics; the Morlet wavelet CWT can still maintain high time-frequency convergence when the rotational speed changes rapidly; the three-stage filtering structure of median filtering, notch filtering, and low-pass filtering can effectively suppress road impact and high-frequency noise from sensors, improving the signal-to-noise ratio of the extracted first-order components to over 25dB.

[0028] Furthermore, step S600 is included before step S300, including: S610: Calculates the root mean square amplitude of the first harmonic component with a period of 10ms, and continuously buffers the amplitude of the last 5 periods. S620: When the root mean square amplitude of three consecutive cycles is greater than the preset vibration threshold of 0.1 m / s², and the current brake pressure sensor reading is greater than 0.3 MPa, it is determined that brake synchronous vibration has occurred. S630: Switch the algorithm state machine from "standby" to "activated", immediately start the brake disc thickness difference estimation module and the compensation torque calculation module, and record the current vehicle speed and braking pressure as the initial parameters for adaptive control.

[0029] The system employs a three-cycle over-threshold detection mechanism to prevent false triggering of single noise spikes. It also requires a braking pressure >0.3MPa to exclude wheel speed fluctuations under non-braking conditions (such as road surface excitation during coasting). The state machine switching delay is less than 30ms to ensure intervention and suppression in the early stages of vibration, resulting in a significant improvement in subjective perception.

[0030] Further, step S300 includes: S310: Through bench testing, under conditions of vehicle speed 60km / h, braking pressure 3MPa, and brake disc temperature 150℃, the amplitude of the first harmonic component corresponding to different known DTV (0~30μm, step size 2μm) is measured to generate a two-dimensional mapping table; the above test is then repeated at 48 operating points with vehicle speeds of 60 / 80 / 100 / 120km / h, pressures of 1 / 3 / 5 / 8MPa, and temperatures of 50 / 150 / 250℃, and interpolation is used to generate a four-dimensional calibration table. S320: Real-time acquisition of current vehicle speed, braking pressure and brake disc temperature, querying the four-dimensional calibration table to obtain the amplitude-DTV mapping curve, and then linearly interpolating to calculate the estimated DTV value based on the currently measured amplitude of the first harmonic component. S330: Outputs the DTV estimate and provides an error margin of ±5μm. When the estimate exceeds the range of 0~40μm, it is set as a diagnostic flag.

[0031] Based on the lookup interpolation of a four-dimensional calibration table (vehicle speed, pressure, temperature, amplitude), the calculation amount is only a few dozen multiplication and addition operations, which is suitable for a 20ms real-time control cycle; the ±5μm accuracy has been verified by bench testing (root mean square error <3.5μm), which meets the control requirements of vehicle manufacturers for brake vibration suppression (usually <10μm); the error boundary output can be used for fault diagnosis.

[0032] Further, step S400 includes the following steps: S410: Calculate the deviation e(k) = DTV_target DTV_estimated(k), where DTV_target = 10μm (acceptable threshold), DTV_estimated(k) is the current period estimate, and e(k) is in μm; S420: The incremental PID control law is used to calculate the compensation torque increment ΔΔT(k) = Kp·[e(k)]. e(k 1)]+ Ki·e(k) + Kd·[e(k) 2e(k 1)+e(k 2)], and then sum them up to obtain the current periodic compensation torque ΔT(k) = ΔT(k 1) + ΔΔT(k); where Kp=200 N·m / μm, Ki=50 N·m / (μm·s), Kd=10 N·m·s / μm, and the control period is 20ms; S430: Calculate the comprehensive gain coefficient based on the current vehicle speed (refer to the table: multiply the gain by 1.2 when the vehicle speed is <80km / h, multiply by 1.0 when the vehicle speed is 80~120km / h, and multiply by 0.7 when the vehicle speed is >120km / h), braking pressure (multiply by 0.8 when the pressure is <2MPa, multiply by 1.0 when the pressure is 2~6MPa, and multiply by 1.2 when the pressure is >6MPa), and brake disc temperature (multiply by 1.0 when the temperature is <100℃, multiply by 0.9 when the temperature is 100~250℃, and multiply by 0.6 when the temperature is >250℃). Then, multiply Kp, Ki, and Kd by this coefficient and recalculate the compensation torque.

[0033] Incremental PID avoids integral saturation, resulting in smooth output; higher compensation is needed at low speeds (due to easily perceptible wheel speed fluctuations), while lower gain at high speeds prevents overshoot and achieves vehicle speed adaptation; under high pressure, the braking torque is large, making the compensation effect more significant, so the gain is appropriately increased; at high temperatures, the friction coefficient decreases, so the gain is reduced to prevent overshoot. Comprehensive adaptation keeps the vibration suppression effect stable within the target range under all operating conditions (steering wheel vibration <1.0m / s²).

[0034] Furthermore, referring to Figure 7 The S430 specifically includes: S431: A three-dimensional gain scheduling table is pre-stored in the ECU's non-volatile memory. The first dimension is vehicle speed: [60,80,100,120,140] km / h; the second dimension is braking pressure: [0.5,1,2,5,8] MPa; and the third dimension is brake disc temperature: [20,100,200,300] ℃. Each grid point stores a set of Kp, Ki, and Kd calibration values, which are obtained through bench optimization. S432: Obtains current vehicle speed (from wheel speed sensor fusion value), braking pressure (from pressure sensor), and brake disc temperature (from infrared sensor or thermal model estimation) via CAN bus. S433: Using the current vehicle speed, pressure, and temperature as indices, calculate the current Kp, Ki, and Kd from the three-dimensional table using trilinear interpolation; S434: If the brake disc temperature exceeds 280℃ or the vehicle speed exceeds 135km / h, multiply the interpolated Kp, Ki, and Kd by 0.4 to reduce them by 60%; if both high temperature and high speed are met, multiply by 0.25.

[0035] The three-dimensional table plus trilinear interpolation ensures accuracy at discrete calibration points and provides a smooth transition at non-calibration points. High temperatures >280℃ and high speeds >135km / h are considered extreme operating conditions. Forcing the gain down to below 40% can effectively avoid instability caused by excessive compensation torque during brake fade or high-speed emergency braking. This strategy has been verified in hardware-in-the-loop simulation with a safety margin of more than 50%.

[0036] Furthermore, following step S400, the following step S700 is also included: Step S700 includes: S710: Compare the estimated DTV values ​​of the left and right front axles. If the difference between their absolute values ​​is greater than 3μm, they are considered inconsistent. Obtain the yaw rate signal (sampling frequency 100Hz, resolution 0.01rad / s) via ESC CAN message. S720: Let the compensation torque of the left wheel be ΔT_L and the compensation torque of the right wheel be ΔT_R. Calculate the difference ΔT_diff = ΔT_L ΔT_R. Using the yaw rate feedback value ω_yaw as input, a PI controller is used to adjust ΔT_diff: ΔT_diff_cmd = Kp_yaw·(ω_target) ω_yaw) + Ki_yaw·∫(ω_target ω_yaw)dt, where ω_target=0 (target for straight-line travel), Kp_yaw=50 N·m / (rad / s), Ki_yaw=20 N·m / rad; S730: Redistribute the compensation torque of the left and right wheels according to ΔT_diff_cmd: ΔT_L_new = ΔT_avg + ΔT_diff_cmd / 2, ΔT_R_new = ΔT_avg ΔT_diff_cmd / 2, where ΔT_avg is the original average compensation torque; output the corrected torque to ESC.

[0037] Reference Figure 6 The control logic is as follows: DTV asymmetry → left and right compensation torque difference distribution → yaw rate feedback → linear stabilization. Utilizing the yaw rate closed-loop, vehicle drift, fishtailing, and directional instability caused by DTV asymmetry can be corrected within 50ms, with a yaw rate error of <0.02rad / s. The PI controller parameters are tuned for braking conditions and do not introduce additional oscillations. This coordination strategy does not rely on high-precision maps or additional sensors, but only reuses existing ESC signals.

[0038] Furthermore, before step S500, step S800 is also included; Step S800 includes: S810: Reads the current vehicle speed, which is obtained from the wheel speed sensor. If the vehicle speed is <60km / h or >140km / h, the output of compensation torque is prohibited; reads the brake pressure. If the pressure is ≤0.3MPa, the output is prohibited. S820: Calculate the absolute value of the original compensation torque. If it exceeds 15% of the current total braking torque, the limit is ±15%. The total braking torque is estimated in real time based on the braking pressure, effective radius of the brake, and coefficient of friction. S830: Calculate the rate of change of the current compensation torque compared to the previous output value, i.e., |ΔT(k) If the rate of change is >50 N·m / s, then the output for this time will be limited to ΔT(k-1) + sign(difference) × 50 N·m / s × Ts; S840: Every 100ms, the brake disc temperature is estimated by the thermal model or directly read from the temperature sensor. If the temperature is >300℃, the compensation torque output is immediately cleared and the algorithm state machine is switched to standby, while the fault code is recorded. When the temperature drops to <280℃ and remains so for 5 seconds, the output is allowed again.

[0039] The speed window of 60~140km / h covers the most common medium and high speed braking vibration range. Low speed vibration is not easily perceived, while high speed vibration poses a great risk, so prohibition or restriction is reasonable. The ±15% limit ensures that the driver has sufficient braking force redundancy. The 50N·m / s change rate limit makes the driver feel no abruptness. The 300℃ high temperature protection for brake disc thermal fade is in line with safety objectives.

[0040] Further step S500 includes: S510: Calculate the required wheel cylinder pressure change based on the compensation torque ΔT (in N·m) and current brake parameters: ΔP = ΔT / (r_eff × μ × A_piston), where r_eff = 0.15m is the effective radius of the brake disc, μ = 0.4 is the coefficient of friction, and A_piston = 0.001m² is the piston area of ​​the wheel cylinder; if ΔT is positive, it indicates pressure increase, and if negative, it indicates pressure decrease; the unit of ΔP is Pa; then it is converted into the number of pressure adjustment steps that ESC can recognize, with each step corresponding to 10kPa; S520: Sends a pressure regulation command frame (ID0x3A0) to the ESC hydraulic unit via the CAN bus at a 20ms cycle, containing the target wheel cylinder address, pressure regulation direction, and regulation step; if the vehicle is equipped with brake-by-wire (EHB), a similar command is sent via the FlexRay bus at a 10ms cycle.

[0041] The torque-to-pressure command conversion formula is based on the brake's physical parameters and can be pre-calibrated with an error of <5%; it is compatible with CAN and FlexRay (two buses, adapted to different vehicle models); the 20ms / 10ms cycle meets real-time requirements, and the brake pressure response delay is less than 40ms, so the driver does not perceive any delay.

[0042] In one specific embodiment of the present invention, the gain reduction operation for high-speed and high-temperature conditions is further explained as follows: when the vehicle speed exceeds 135km / h or the brake disc temperature exceeds 280°C, the electronic control unit will simultaneously reduce the proportional gain, integral gain, and derivative gain of the adaptive PID to below 40% of the calibration value at normal temperature and speed.

[0043] The core consideration in this design is as follows: Under high-speed conditions, the ratio of the braking system response time to the wheel rotation cycle increases. Excessive gain can lead to an excessively large phase lead of the compensation torque, causing the braking torque fluctuation to be amplified in the opposite direction, i.e., "overcompensation." Under high-temperature conditions, the friction coefficient between the brake disc and brake pads decreases and its volatility increases. If the original gain is maintained, the linear relationship between the amplitude of the compensation torque and the actual fluctuation amplitude is disrupted, easily causing torque oscillation, which in turn affects the longitudinal and lateral stability of the vehicle. By reducing the gain, the adjustment range of the compensation torque is compressed to a safe range. Actual measurements show that when the gain reduction coefficient is ≤0.4, the change in yaw rate during high-speed emergency braking can be controlled within 0.03 rad / s, far below the driver's perceptible threshold of 0.1 rad / s, thus ensuring the vibration suppression effect while eliminating instability.

[0044] This invention also provides an embodiment of a vehicle brake shudder suppression system, comprising: a processor, a memory, and a CAN transceiver. The memory stores a shudder suppression program and a calibration table, and the CAN transceiver is connected to the ESC (Electronic Stability Control). When the processor executes the program in the memory, it implements the active brake shudder suppression method described above. This device is integrated into the ESC main control board without adding independent hardware.

[0045] All methods and steps are implemented by executing the program through the processor, which facilitates software upgrades and iterations; no independent ECU is added, only existing ESC / brake-by-wire controller resources are reused, and the incremental hardware cost is zero; the device is independent of specific vehicle models and can be quickly adapted to different vehicle platforms by flashing software, which facilitates industrialization.

[0046] refer to Figures 1 to 3 In a specific embodiment, the implementation conditions are as follows: The vehicle is equipped with four-wheel wheel speed sensors, ESC / brake-by-wire unit, and brake pressure / temperature signal. Controller: Body Controller / ESC Domain Controller Operating conditions: DTV=25μm, vehicle speed 80km / h, medium braking intensity Experimental comparison data: parameter No compensation passive vibration reduction This invention DTV(μm) 25 25 25 Steering wheel vibration (m / s²) 2.8 2.1 0.9 Pedal vibration (N) 45 35 15 Subjective rating (1-10) 3 5 8 Braking distance change 0% 0% +2% Energy consumption changes 0% 0% +1.5% Reference Figure 4 and Figure 5 As shown in the table data, under the same DTV conditions, the present invention has a much better braking vibration suppression effect than the passive solution, greatly improves driving comfort, and has an acceptable impact on braking distance and energy consumption, thus possessing mass production engineering value.

[0047] This invention also provides a vehicle, including a memory, a processor, and a program stored in the memory and executable on the processor. When the program is executed by the processor, it implements the aforementioned method for active suppression of braking vibration based on wheel speed signals.

[0048] The processor can be implemented using a general-purpose central processing unit (CPU), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this application.

[0049] The memory can be implemented in the form of read-only memory (ROM), static storage device, dynamic storage device, or random access memory (RAM). The memory can store the operating system and other applications. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory and is called and executed by the processor.

[0050] The vehicle also includes one of the aforementioned vehicle brake vibration suppression systems. Specifically, the vehicle can be a private car, such as a sedan, SUV, MPV, or pickup truck. The vehicle can also be a commercial vehicle, such as a van, bus, small truck, or large semi-trailer. The vehicle can be a gasoline-powered vehicle or a new energy vehicle. When the vehicle is a new energy vehicle, it can be a hybrid vehicle or a pure electric vehicle.

[0051] According to an embodiment of the present invention, a computer-readable storage medium is stored thereon, which, when executed by a processor, implements the above-described method for active suppression of braking vibration based on wheel speed signals.

[0052] The computer-readable storage medium of this invention can be any combination of one or more computer-readable media. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this invention, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0053] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0054] Program code contained on a computer-readable medium may be transmitted using any suitable medium, including but not limited to: wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0055] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0056] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0057] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for actively suppressing braking vibration based on wheel speed signals, characterized in that, include: Acquire the wheel speed signal of at least one wheel, wherein the sampling frequency of the wheel speed signal is not less than 2kHz; Time-frequency analysis was performed on the wheel speed signal to extract the first-order harmonic component that is synchronized with the wheel rotation; Based on the amplitude of the first harmonic component, the current brake disc thickness difference is estimated in real time; The deviation between the acceptable threshold is set, and the compensation torque is calculated by using an adaptive control strategy based on the estimated deviation between the brake disc thickness difference and the acceptable threshold. The compensation torque is output to the braking actuator to adjust the wheel cylinder pressure of the corresponding wheel and actively suppress the fluctuation of braking torque.

2. The active braking vibration suppression method according to claim 1, characterized in that, The step of performing time-frequency analysis on the wheel speed signal to extract the first-order harmonic component synchronized with the wheel rotation includes: The wheel speed signal is subjected to time-frequency transformation using short-time Fourier transform or continuous wavelet transform; Separate the first harmonic component that has the same rotational frequency as the wheel from the transformation result; Filter out non-braking excitation interference introduced by road bumps and sensor noise.

3. The method according to claim 1, characterized in that, Before estimating the current brake disc thickness difference in real time based on the amplitude of the first harmonic component, the method further includes: The amplitude of the extracted first harmonic component is monitored; When the amplitude of the first harmonic component exceeds the preset vibration threshold, it is determined that braking synchronous vibration has occurred. In response to the determination, the subsequent steps of brake disc thickness difference estimation and compensation torque calculation are activated.

4. The active braking vibration suppression method according to claim 1, characterized in that, The step of estimating the current brake disc thickness difference in real time based on the amplitude of the first harmonic component includes: Establish the mapping relationship between the amplitude of the first harmonic component and the thickness difference of the brake disc; Based on the amplitude of the first harmonic component at the current moment, the corresponding estimated value of the brake disc thickness difference can be obtained by looking up a table or by calculation. The output estimates the brake disc thickness difference with an accuracy of ±5μm.

5. The active braking vibration suppression method according to claim 1, characterized in that, The deviation between the estimated brake disc thickness difference and an acceptable threshold is used to calculate the compensation torque using an adaptive control strategy, including: Calculate the deviation e(k) = DTV_target DTV_estimated(k), where e(k) represents the deviation at the current time, DTV_target is the preset acceptable threshold, and DTV_estimated(k) is the estimated brake disc thickness difference at the current time; The basic compensation torque is calculated using a PID control law: ΔT(k) = Kp·e(k) + Ki·Σe(i) + Kd·[e(k)] e(k 1)], where ΔT(k) represents the compensation torque at the current moment, Kp, Ki, and Kd represent the proportional gain, integral gain, and differential gain, respectively, Σe(i) represents the cumulative sum of the deviations, and e(k 1) Indicates the deviation from the previous moment; Based on at least one of the following status information: current vehicle speed, braking pressure, and brake disc temperature, the gain values ​​of Kp, Ki, and Kd are dynamically adjusted to obtain the adaptive compensation torque.

6. The active braking vibration suppression method according to claim 5, characterized in that, The step of dynamically adjusting the gain values ​​of Kp, Ki, and Kd based on at least one of the following state information: current vehicle speed, braking pressure, and brake disc temperature, includes: A three-dimensional gain scheduling table is pre-stored, with vehicle speed, braking pressure, and brake disc temperature as index dimensions. Obtain the current vehicle speed, braking pressure, and brake disc temperature; The corresponding Kp, Ki, and Kd gain values ​​are obtained by querying the three-dimensional gain scheduling table based on the current vehicle speed, braking pressure, and brake disc temperature. When the brake disc temperature exceeds the preset high temperature threshold or the vehicle speed exceeds the preset high speed threshold, the gain values ​​of Kp, Ki, and Kd will be reduced to less than 50% of the calibrated values.

7. The active braking vibration suppression method according to claim 1, characterized in that, After calculating the compensation torque using an adaptive control strategy based on the deviation between the estimated brake disc thickness difference and an acceptable threshold, the method further includes: When it is determined that the brake disc thickness difference between the left and right front axle wheels is inconsistent, the vehicle's yaw rate feedback signal is obtained. Based on the yaw rate feedback, the compensation torque output of the left and right wheels is coordinated; It generates a corrective yaw moment to maintain straight-line stability.

8. The active braking vibration suppression method according to claim 1, characterized in that, Before outputting the compensation torque to the braking actuator, the method further includes: Determine if the current vehicle speed is within the range of 60–140 km / h and the braking pressure is greater than 0.3 MPa; otherwise, prohibit the output of compensation torque. The compensation torque is limited to within ±15% of the total braking torque; The rate of change of the compensation torque is limited to no more than 50 N·m / s; The brake disc temperature is obtained, and when the brake disc temperature exceeds 300°C, the compensation torque output is discontinued.

9. The active braking vibration suppression method according to claim 1, characterized in that, The step of outputting the compensation torque to the braking actuator includes: The compensation torque is converted into a wheel cylinder pressure adjustment command; Send the pressure regulation command to the ESC hydraulic unit or the brake-by-wire unit.

10. A vehicle brake vibration suppression system, comprising a processor and a memory, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the active braking vibration suppression method according to any one of claims 1 to 8.

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