A vehicle brake feedback process for improving recovery

Abstract

The present application relates to the technical field of vehicle braking control, and discloses a vehicle braking feedback process for improving recovery rate, comprising: acquiring real-time pressure data of a brake wheel cylinder, calculating the rate of change of pressure with time to determine a real-time pressure building rate, building a dynamic constraint boundary for motor negative torque exit based on the real-time pressure building rate, establishing a correlation constraint relationship between the feedback braking torque exit gradient and the hydraulic braking circuit pressure building gradient, and adjusting the feedback braking torque in combination with the wheel slip rate deviation, wherein the present application limits the motor negative torque decay gradient through the correlation constraint relationship, so that the motor torque exit intensity is limited to the physical pressure building increment of the hydraulic circuit, the fluid pipeline pressure building delay is compensated, the total braking torque drop dead zone is eliminated, and the effective intervention time of electric braking is extended.

Description

Technical Field

[0001] This invention belongs to the field of vehicle braking control technology, and particularly relates to a vehicle braking feedback process that improves the recovery rate. Background Technology

[0002] Current electro-hydraulic hybrid braking systems achieve vehicle kinetic energy recovery through the coordination of regenerative braking torque and hydraulic braking torque. However, the hydraulic braking actuator is limited by the fluid viscosity coefficient and mechanical clearance, resulting in an inherent response delay during pressure build-up, typically in the range of 10ms to 100ms. The motor torque response is in the millisecond range. This asymmetric dynamic response characteristic causes a time axis deviation in the electro-hydraulic torque during the handover transient. The control logic also lacks means to compensate for the electro-hydraulic handover transient. For example, Chinese invention patent application CN121133431A discloses an energy recovery control method, device, equipment, and medium for electric vehicles. The disclosed content is based on a preset static oil pressure threshold of 0.8MPa and a vehicle speed range to determine the negative torque signal output logic.

[0003] Existing technologies balance braking smoothness and recovery rate by setting a fixed torque distribution ratio and static switching slope to compensate for the deceleration drop caused by hydraulic pressure build-up hysteresis. When the control system triggers the switching of the braking source, it usually forces the motor torque to withdraw in advance to reserve static response redundancy. This strategy causes the motor to stop working during the window period when it still has energy recovery potential, resulting in a loss of recovery efficiency.

[0004] Therefore, how to eliminate the response dead zone of the electro-hydraulic hybrid braking system during torque switching and accurately align the exit process of regenerative braking torque with the actual physical response of the hydraulic system is the technical problem to be solved by this invention. Summary of the Invention

[0005] This invention proposes a vehicle braking feedback process to improve the recovery rate, comprising the following steps:

[0006] Step S1: Real-time acquisition of physical pressure data of the brake wheel cylinders in the vehicle braking circuit;

[0007] Step S2: Retrieve the preset noise filtering threshold to smooth the physical pressure data, and calculate the rate of change of brake wheel cylinder pressure over time based on the filtered physical pressure data, so as to extract the real-time pressure build-up rate of the hydraulic brake circuit under the current ambient temperature.

[0008] Step S3: Calculate the dynamic constraint boundary for the motor's negative torque withdrawal based on the real-time pressure build-up rate. Transform the hydrodynamic response characteristics of the hydraulic braking circuit into time-domain constraints for the motor's negative torque decay through the dynamic constraint boundary, so as to establish the nonlinear correlation constraint relationship between the motor's negative torque withdrawal gradient and the hydraulic braking circuit's pressure build-up gradient.

[0009] Step S4: After receiving the brake energy recovery exit command, the wheel slip ratio deviation value is collected in real time, and the feedback adjustment of the motor negative torque is completed by combining the dynamic constraint boundary and the wheel slip ratio deviation value. Among them, when the real-time pressure build-up rate decreases due to the increase in brake fluid viscosity caused by the sudden change in ambient temperature, the nonlinear correlation constraint relationship limits the decrease slope of the motor negative torque through the dynamic constraint boundary, so that the withdrawal strength of the motor negative torque during the switching transient process is always limited to the actual effective pressure increment of the hydraulic braking circuit under the current pipeline physical state. In this way, the total braking torque drop into the vacuum zone is eliminated by offsetting the pressure build-up response delay of the hydraulic braking circuit, and the effective intervention time of electric brake recovery is extended to the physical boundary where the wheel slip ratio does not exceed the ground adhesion limit.

[0010] Preferably, the process of constructing dynamic constraint boundaries in step S3 includes: obtaining preset torque coupling coefficient and torque response step time parameters; performing linear mapping processing using real-time pressure build-up rate and torque coupling coefficient to calculate the maximum allowable decrease in motor negative torque within the current control cycle; and multiplying the maximum allowable decrease by the torque response step time parameters to define a hard slope constraint during the motor negative torque exit process.

[0011] Preferably, in step S1, physical pressure data is acquired by a pressure sensor located at the cylinder end of the brake wheel; in step S2, differential calculation is performed on the digital pressure values ​​of adjacent sampling periods, and the derivative of pressure with respect to time is calculated in combination with the sampling frequency, so as to capture in real time the transient pressure build-up characteristics of the fluid inside the hydraulic braking circuit caused by the mechanical dead zone of the valve core or the obstruction of the pipeline, thereby providing physical feedback for the calculation of dynamic constraint boundaries.

[0012] Preferably, when completing the feedback adjustment of the motor negative torque in step S4, the method further includes: real-time monitoring of the bus voltage and real-time speed of the drive motor to determine the real-time power generation limit of the drive motor; when the exit rate defined by the dynamic constraint boundary is lower than the safe exit slope corresponding to the real-time power generation limit, the dynamic constraint boundary is used as the main control reference for adjustment to maintain the kinetic energy recovery intensity; if the dynamic constraint boundary reflects the stagnation of pressure growth, an early warning signal is output.

[0013] Preferably, before step S1, an initialization calibration step is also included: under the static condition of the vehicle, the hydraulic braking circuit is controlled to perform multiple pressure build-up cycle tests to obtain the pipeline response characteristic curves at different ambient temperatures; based on the pipeline response characteristic curves, the noise filtering threshold of the real-time pressure build-up rate is calibrated, and the noise filtering threshold is stored in the controller for smoothing the acquired raw signal in step S2 to eliminate system background noise.

[0014] Preferably, in step S3, the nonlinear correlation constraint relationship also introduces a vehicle speed correction step, including: collecting the current longitudinal speed of the vehicle; querying the preset recovery weight mapping relationship table according to the current longitudinal speed to obtain the speed correction factor; using the speed correction factor to perform nonlinear weighting processing on the dynamic constraint boundary, and increasing the locking strength of the motor negative torque when the vehicle is in the high-speed range above 80km / h, so as to extend the time window for high-value kinetic energy recovery.

[0015] Preferably, the process of obtaining the wheel slip ratio deviation value in step S4 includes: collecting the real-time angular velocity of each wheel through the wheel speed sensor; calculating the real-time slip ratio of each wheel in combination with the vehicle body reference speed; comparing the real-time slip ratio with the preset target recovery slip ratio range to calculate the wheel slip ratio deviation value, and using the wheel slip ratio deviation value as the proportional correction term for motor negative torque feedback adjustment.

[0016] Preferably, the process of determining the torque coupling coefficient includes: real-time monitoring of the displacement change rate of the brake pedal; identifying the driver's real-time braking intensity requirement based on the displacement change rate; and increasing the value of the torque coupling coefficient when the real-time braking intensity requirement exceeds the preset value of 0.5g acceleration to shorten the exit time of the motor's negative torque and ensure that the hydraulic braking system can quickly take over to meet the emergency braking safety requirements.

[0017] Preferably, after completing step S4, a torque compensation closed-loop monitoring step is also included: monitoring the actual attenuation of the motor's negative torque and the actual compensation of the brake wheel cylinder pressure; when the torque deviation between the actual attenuation and the actual compensation exceeds 5%, the attenuation gradient defined in step S3 is corrected in real time based on the torque deviation, and residual offset is achieved by adjusting the given current loop of the motor to realize the closed-loop smoothness of the vehicle's total braking torque at the handover of the electro-hydraulic power source.

[0018] Compared to existing technologies, the vehicle braking feedback process of this invention, which improves the recovery rate, has the following advantages:

[0019] 1. In the vehicle braking feedback process, a physical interlocking logic of electric braking attenuation gradient and hydraulic real-time pressure build-up gradient is adopted to transform the actual response rate of the hydraulic actuator into a hard constraint boundary for the motor negative torque withdrawal. Under this mechanism, the withdrawal process of the motor negative torque is constrained by the actual pressure build-up increment of the hydraulic system under the current pipeline state, eliminating the torque handover vacuum zone caused by the asymmetry of electro-hydraulic response, and ensuring the smooth connection of the total braking force during the switching transient process.

[0020] 2. The time derivative of the brake wheel cylinder pressure is used to directly feed back the fluid dynamics state inside the pipeline, enabling the control system to adaptively counteract the effects of drastic changes in brake fluid viscosity caused by ambient temperature variations and the mechanical dead zone of the solenoid valve. Even under low-temperature conditions where fluid pressure build-up is slow, the negative torque of the motor is forcibly locked by the controller to maintain the recovery state until the hydraulic system establishes an equivalent physical pressure compensation amount, thus avoiding premature loss of kinetic energy due to preset static safety redundancy in conventional processes.

[0021] 3. By constructing a two-way dependent closed loop of electric braking and hydraulic braking, the effective intervention time of electric braking is extended to the physical limit boundary. Under the premise of ensuring that the wheel slip ratio does not exceed the adhesion limit, this process achieves a deep fit between the negative torque of electric braking and the ground adhesion, widens the time integral area of ​​the conversion of braking kinetic energy into electrical energy, and breaks the recovery rate limitation caused by the fluid resistance characteristics of the hydraulic system. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of the electro-hydraulic torque dynamic constraint for real-time pressure gradient building according to the present invention;

[0023] Figure 2 This is the logic diagram of motor negative torque feedback regulation and closed-loop monitoring based on the multi-dimensional parameter fusion of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0025] It should be noted that all directional and positional terms used in this invention, such as: up, down, left, right, front, back, vertical, horizontal, inner, outer, top, bottom, transverse, longitudinal, center, etc., are only used to explain the relative positional relationship and connection between components in a specific state (as shown in the accompanying drawings). They are only for the convenience of describing this invention and do not require that this invention be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. In addition, the descriptions of "first," "second," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0026] In the description of this invention, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0027] In the description of this specification, references to the terms "an embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," 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 present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example, and the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0028] A vehicle braking feedback process for improving recovery rate includes the following steps:

[0029] Step S1: Real-time acquisition of physical pressure data of the brake wheel cylinders in the vehicle braking circuit;

[0030] Step S2: Retrieve the preset noise filtering threshold to smooth the physical pressure data, and calculate the rate of change of brake wheel cylinder pressure over time based on the filtered physical pressure data, so as to extract the real-time pressure build-up rate of the hydraulic brake circuit under the current ambient temperature.

[0031] Step S3: Calculate the dynamic constraint boundary for the motor's negative torque withdrawal based on the real-time pressure build-up rate. Transform the hydrodynamic response characteristics of the hydraulic braking circuit into time-domain constraints for the motor's negative torque decay through the dynamic constraint boundary, so as to establish the nonlinear correlation constraint relationship between the motor's negative torque withdrawal gradient and the hydraulic braking circuit's pressure build-up gradient.

[0032] Step S4: After receiving the brake energy recovery exit command, the wheel slip ratio deviation value is collected in real time, and the feedback adjustment of the motor negative torque is completed by combining the dynamic constraint boundary and the wheel slip ratio deviation value. Among them, when the real-time pressure build-up rate decreases due to the increase in brake fluid viscosity caused by the sudden change in ambient temperature, the nonlinear correlation constraint relationship limits the decrease slope of the motor negative torque through the dynamic constraint boundary, so that the withdrawal strength of the motor negative torque during the switching transient process is always limited to the actual effective pressure increment of the hydraulic braking circuit under the current pipeline physical state. In this way, the total braking torque drop into the vacuum zone is eliminated by offsetting the pressure build-up response delay of the hydraulic braking circuit, and the effective intervention time of electric brake recovery is extended to the physical boundary where the wheel slip ratio does not exceed the ground adhesion limit.

[0033] Preferably, the process of constructing dynamic constraint boundaries in step S3 includes: obtaining preset torque coupling coefficient and torque response step time parameters; performing linear mapping processing using real-time pressure build-up rate and torque coupling coefficient to calculate the maximum allowable decrease in motor negative torque within the current control cycle; and multiplying the maximum allowable decrease by the torque response step time parameters to define a hard slope constraint during the motor negative torque exit process.

[0034] Preferably, in step S1, physical pressure data is acquired by a pressure sensor located at the cylinder end of the brake wheel; in step S2, differential calculation is performed on the digital pressure values ​​of adjacent sampling periods, and the derivative of pressure with respect to time is calculated in combination with the sampling frequency, so as to capture in real time the transient pressure build-up characteristics of the fluid inside the hydraulic braking circuit caused by the mechanical dead zone of the valve core or the obstruction of the pipeline, thereby providing physical feedback for the calculation of dynamic constraint boundaries.

[0035] Preferably, in step S4, the feedback adjustment of the motor negative torque follows the following quantitative control rules: ,in, This is the dynamic constraint value for the motor to exit with negative torque. For real-time pressure build-up rate, The torque coupling coefficient is... The torque response step time parameter; the exit gradient of the motor's negative torque is subject to dynamic constraints. Real-time constraints: When the real-time pressure build-up rate decreases, the dynamic constraint value decreases synchronously.

[0036] Preferably, when completing the feedback adjustment of the motor negative torque in step S4, the method further includes: real-time monitoring of the bus voltage and real-time speed of the drive motor to determine the real-time power generation limit of the drive motor; when the exit rate defined by the dynamic constraint boundary is lower than the safe exit slope corresponding to the real-time power generation limit, the dynamic constraint boundary is used as the main control reference for adjustment to maintain the kinetic energy recovery intensity; if the dynamic constraint boundary reflects the stagnation of pressure growth, an early warning signal is output.

[0037] Preferably, before step S1, an initialization calibration step is also included: under the static condition of the vehicle, the hydraulic braking circuit is controlled to perform multiple pressure build-up cycle tests to obtain the pipeline response characteristic curves at different ambient temperatures; based on the pipeline response characteristic curves, the noise filtering threshold of the real-time pressure build-up rate is calibrated, and the noise filtering threshold is stored in the controller for smoothing the acquired raw signal in step S2 to eliminate system background noise.

[0038] Preferably, in step S3, the nonlinear correlation constraint relationship also introduces a vehicle speed correction step, including: collecting the current longitudinal speed of the vehicle; querying the preset recovery weight mapping relationship table according to the current longitudinal speed to obtain the speed correction factor; using the speed correction factor to perform nonlinear weighting processing on the dynamic constraint boundary, and increasing the locking strength of the motor negative torque when the vehicle is in the high-speed range above 80km / h, so as to extend the time window for high-value kinetic energy recovery.

[0039] Preferably, the process of obtaining the wheel slip ratio deviation value in step S4 includes: collecting the real-time angular velocity of each wheel through the wheel speed sensor; calculating the real-time slip ratio of each wheel in combination with the vehicle body reference speed; comparing the real-time slip ratio with the preset target recovery slip ratio range to calculate the wheel slip ratio deviation value, and using the wheel slip ratio deviation value as the proportional correction term for motor negative torque feedback adjustment.

[0040] Preferably, the process of determining the torque coupling coefficient includes: real-time monitoring of the displacement change rate of the brake pedal; identifying the driver's real-time braking intensity requirement based on the displacement change rate; and increasing the value of the torque coupling coefficient when the real-time braking intensity requirement exceeds the preset value of 0.5g acceleration to shorten the exit time of the motor's negative torque and ensure that the hydraulic braking system can quickly take over to meet the emergency braking safety requirements.

[0041] Preferably, after completing step S4, a torque compensation closed-loop monitoring step is also included: monitoring the actual attenuation of the motor's negative torque and the actual compensation of the brake wheel cylinder pressure; when the torque deviation between the actual attenuation and the actual compensation exceeds 5%, the attenuation gradient defined in step S3 is corrected in real time based on the torque deviation, and residual offset is achieved by adjusting the given current loop of the motor to realize the closed-loop smoothness of the vehicle's total braking torque at the handover of the electro-hydraulic power source.

[0042] Example 1: When a vehicle is driven in an environment of -20℃ and the brake fluid viscosity increases due to the low temperature, the hydraulic actuator experiences a pressure build-up delay after receiving the regenerative braking disengagement command. This causes a physical asymmetry in the pressure build-up process of the hydraulic braking circuit relative to the electric motor braking response, resulting in unexpected fluctuations in the vehicle's braking torque at the moment of torque switching. The vehicle's braking circuit acquires real-time physical pressure data of the brake wheel cylinders through pressure sensors. The physical pressure data is filtered using a noise filtering threshold. The rate of change of brake wheel cylinder pressure over time is calculated from the filtered physical pressure data to extract the real-time pressure build-up rate of the hydraulic braking circuit under the current environmental conditions. Based on the physical equivalence principle of fluid volumetric modulus and pipeline elastic deformation, within a millisecond-level control cycle, the change in hydraulic pipeline volume and the transient fluid pressure exhibit quasi-static linear characteristics. The system, relying on fundamental physical laws, abstracts and solidifies the complex intrinsic damping properties of the hydraulic circuit hardware into a constant torque coupling coefficient, eliminating the risk of computational divergence caused by nonlinear fluid fluctuations in discrete sampling. The controller then acquires the preset torque coupling coefficient. Torque response step time parameter And according to the formula Determine the dynamic constraint value for motor negative torque withdrawal. ,in, This is the dynamic constraint value for the motor to exit with negative torque. For real-time pressure build-up rate, The torque coupling coefficient is... This refers to the torque response step time parameter.

[0043] The exit gradient of the motor's negative torque is subject to dynamic constraints. The constraint limits the reduction strength of the motor's negative torque to the physical pressure build-up increment of the hydraulic braking circuit. By using dynamic constraint boundaries, the hydrodynamic response characteristics of the hydraulic braking circuit are transformed into time-domain constraints on the motor's negative torque decay, eliminating the drop in total braking torque caused by the pressure build-up delay in the fluid pipeline. This ensures smooth braking connection while improving the vehicle's braking energy recovery rate. In the physical implementation of this counterbalancing mechanism, although the torque coupling coefficient is preset to a constant, the high-order nonlinear dynamic characteristics of the fluid exhibited by the drastic viscosity change at extreme low temperatures are completely captured in real time by the pressure sensor at the front end of the brake wheel cylinder and objectively reflected in the transient changes of the discretely extracted real-time pressure build-up rate. This mechanism allows the constant coupling coefficient to be used only to characterize the immutable intrinsic volumetric stiffness of the hardware, while the viscous damping nonlinear variable caused by ambient temperature is directly introduced into the system by the dynamic variable of the real-time pressure build-up rate. The combination of the two allows the boundary constraints to accurately follow the extremely complex viscosity decay inside the pipeline in a physically self-consistent manner, thus eliminating the need to build a complex nonlinear high-order fluid observer at the engineering level.

[0044] When the vehicle's braking control system faces a sudden drop in the power battery's recharge power, resulting in a limit regenerative torque... The absolute value is less than that determined by the real-time pressure build-up rate. When calculating the dynamic torque requirement, the processor compares the dynamic constraint values ​​in real time. With the torque recovered by the limit The derived unit-cycle torque decay is used to select the main control reference for the current cycle. If the exit slope reflected by the physical pressure build-up gradient of the hydraulic braking circuit is within the electromagnetic safety range of the electric drive system, the dynamic exit logic based on the actual hydraulic response is maintained to maintain the kinetic energy recovery intensity. If a battery voltage fluctuation is detected, triggering the overvoltage protection boundary of the electric drive system and causing the ultimate recovery torque to be reduced... If the exit rate is lower than the dynamic constraint boundary, the system automatically activates the generator power limiting torque value as the highest priority control signal to clamp the exit strength of the motor negative torque. This prevents system back-charging overcurrent through the interlocking of the physical boundaries of the electro-hydraulic dual domains, and keeps the total braking torque fluctuation of the vehicle within 1.5% of the full scale at the moment of torque switching.

[0045] Example 2: This test was conducted on a vehicle braking performance test bench equipped with a high and low temperature environment simulation chamber. This test platform integrates a high-precision electro-hydraulic composite braking simulation system to simulate the dynamic response of brake fluid in extreme temperature ranges. The physical pressure data used in the test came from a pressure sensor installed at the front end of the brake wheel cylinder. The sensor's sampling frequency was set to 1000Hz, its range was 0MPa to 20MPa, and its measurement accuracy was 0.05%FS. In the initial test phase, the braking system temperature was adjusted to -20℃ in the environmental simulation chamber and the vehicle was immersed at this temperature for 4 hours to allow the brake fluid viscosity to reach a low-temperature steady state. The core parameter, torque response step time, was then determined. At this time, it is necessary to balance the real-time performance of system control with the computational load of the controller. If the value is too large, it will be unable to capture the high-frequency pressure fluctuations during the hydraulic pressure build-up process, causing the motor torque to lag behind the pressure rise, resulting in overlapping braking torque. If the value is too small, it will increase the interrupt response frequency of the controller; based on the typical pressure build-up period of the hydraulic braking system in the brake fluid viscous state being between 80ms and 150ms, this experiment determined... The sampling time is 10ms, thus providing a sampling resolution 10 times that of the voltage build-up period while maintaining the controller's interrupt duty cycle below 35%. The experimental group, i.e., the sample group of this invention, adopts dynamic constraint boundary control logic, and its torque coupling coefficient is... The pressure was set to 1.2 Nm / MPa to simulate an engineering environment. Gaussian white noise with a signal-to-noise ratio of 25 dB was superimposed on the pressure sensor's acquired signal. In the initial state, the brake pedal opening jumped to 30%, triggering the regenerative braking exit command. The original pressure data exhibited signal jitter during the initial pressure build-up phase, with an amplitude of 0.08 MPa. This invention's sample was processed through smoothing filtering to remove high-frequency noise, extracting the real-time pressure build-up rate. The measured initial value was 3.85 MPa / s, which increased to 7.21 MPa / s as the viscous fluid was transported to the wheel cylinder.

[0046] The comparison sample group used a fixed motor torque exit slope, meaning that after receiving the exit command, the motor torque linearly decayed to 0 within 100ms. In the sample group of this invention, the slope is calculated using the formula... The calculated dynamic constraint values It adjusts dynamically according to changes in the pressure gradient; among which, This is the dynamic constraint value for the motor to exit with negative torque. For real-time pressure build-up rate, The torque coupling coefficient is... For the torque response step time parameter, when The calculated single-step decay amount at 3.85 MPa / s The torque was 0.046 Nm. Data monitoring results showed that, in the comparison sample group, due to the use of a fixed slope, the motor torque withdrawal rate exceeded the hydraulic pressure increase rate during the hydraulic pressure build-up delay period caused by brake fluid viscosity, resulting in a 12.5% ​​instantaneous drop in total braking torque at 45 ms. In contrast, in the sample group of this invention, due to the dynamic constraint value... Follow Synchronous reduction, the rate at which the negative torque of the motor exits is limited by the actual physical pressure-building capacity of the hydraulic system, suppressing the total braking torque fluctuation rate to within 1.8%. To verify the rationality of the numerical range, an out-of-range control group is established, when the torque coupling coefficient... When the pressure was set to 5.5 Nm / MPa, the calculated step decay was too fast, causing the motor torque to exit before the hydraulic pressure reached a steady state. The energy recovery contribution decreased by 18.3% compared to the sample of this invention. A gradient verification test was set up, and the braking exit test of the same intensity was compared in environments of -20℃, -10℃ and 0℃. The data showed that as the ambient temperature decreased from 0℃ to -20℃, the brake fluid viscosity increased. The extension of the energy recovery time of the sample of this invention increased from 15.2ms to 102.5ms. The dynamic constraint boundary eliminated the phase difference between the motor response and fluid hindrance by tracing the consistency of the physical gradient of the hydraulic circuit. The braking energy recovery utilization rate of the sample of this invention reached 86.4% under the condition of -20℃, which is 15.2 percentage points higher than the 71.2% of the comparison sample. Moreover, the wheel slip ratio deviation was always maintained within the safety target threshold of 0.02, realizing the synergy between braking smoothness and energy recovery intensity.

[0047] Example 3: The vehicle braking control system is deployed on a hardware platform with different pipeline stiffness and hydraulic response characteristics. The vehicle braking circuit is equipped with a pressure sensor with a measurement resolution better than 0.1%. During the system initialization phase, the controller drives the hydraulic pump to establish braking pressure with pressure increase gradients of 2MPa / s, 5MPa / s, and 10MPa / s, respectively, and records in real time the physical lag time generated by the hydraulic system from receiving the command to the actual pressure increase of 10%. According to the formula Determine the torque coupling coefficient ;in, The torque coupling coefficient is... This refers to the change in the rated regenerative torque of the drive motor under test conditions. This represents the measured pressure change in the brake wheel cylinder. As the physical lag time, this determination procedure makes the physical slope of the motor's negative torque withdrawal limited by the pressure response characteristics of the hydraulic braking circuit.

[0048] The system utilizes a sliding time window based on five sampling periods to monitor the raw pulse frequency of the wheel speed sensor. The processor calculates the statistical variance of the wheel speed data within the sliding time window and compares it with a preset signal confidence threshold. When the statistical variance is less than the signal confidence threshold, the system calculates the real-time slip ratio based on the current vehicle reference speed and wheel axle angular velocity, and subtracts it from the preset braking safety target value to determine the wheel slip ratio deviation. This processing method converts the raw wheel speed signal into a real-time feedback parameter with physical reliability, supporting the calculation of dynamic constraint boundaries. Based on the vehicle's nonlinear dynamics model under sliding friction conditions, the system executes a state judgment quantization procedure to correct the boundary output, extracts the calculated wheel slip ratio deviation value, and determines when the deviation value crosses the zero threshold. When this deviation value crosses the zero threshold, the controller calls the proportional-integral control algorithm to solve for negative torque. The torque compensation parameter is directly superimposed on the basic extracted dynamic constraint value to form a corrected limit command sent to the electric drive execution layer. In the execution logic of the proportional-integral control algorithm, the system calculation module uses the calculated wheel slip ratio deviation value as input, which is solved by the algorithm and responds to the output to generate the negative torque compensation parameter. To ensure control stability, the proportional coefficient calibration range inside the algorithm is limited to 50Nm to 80Nm to provide instantaneous strong correction torque for sudden slip. The integral coefficient is set between 10Nm / s and 20Nm / s to smooth and eliminate steady-state slip error. The tuning boundary of the above coefficients is extracted based on the anti-lock braking bench limit test data of the same chassis on low-adhesion road surface, thus establishing a verifiable engineering safety boundary for the torque conversion of slip deviation.

[0049] To match the physical kinetic energy baseline under high-speed driving, the system uses a logic styling function representing the smooth transition of the state to establish a longitudinal vehicle speed quantization mapping relationship. A pre-defined recovery weight mapping table is generated by offline calculation of this logic styling function and writing the resulting array into the controller's read-only memory. The specific mathematical expression of this logic styling function is as follows: ,in, The velocity correction factor to be determined is... For real-time longitudinal vehicle speed, The calibrated smooth transition center speed is set at 100 km / h, taking into account actual operating conditions. The curve steepness coefficient, calibrated to 0.15 based on the vehicle's high-speed braking smoothness requirements, establishes a mapping relationship through this function, causing the speed correction factor to exhibit a non-linear S-shaped smooth increase when entering the high-speed range. This avoids a step-like torque surge triggered when the vehicle speed exceeds the boundary. When the longitudinal vehicle speed exceeds the 80km / h calibration baseline, the controller uses the real-time longitudinal vehicle speed as the input function to calculate the speed correction factor within the range of 1.0 to 1.5. The dynamic constraint value is then divided by the speed correction factor, forcibly reducing the negative torque attenuation at each step. The slope, the rate of change of brake pedal displacement, maps to the physical injection acceleration of the brake master cylinder. When the rate of change indicates that the braking demand exceeds the corresponding 0.5g deceleration master cylinder pressure build-up characteristic point, the controller triggers a response reconfiguration action. This involves multiplying the torque coupling coefficient obtained from the basic calibration by an emergency gain factor within the range of 1.5 to 2.0. The amplified coefficient synchronously amplifies the dynamic constraint value, calculating the single-step step size, and driving the generator's negative torque to converge to zero within an extremely short time domain. Within the dynamic control cycle after receiving the brake energy recovery exit command, the processor uses the aforementioned determined torque coupling coefficient... The system adjusts the motor's negative torque based on the deviation of the wheel slip ratio. It uses a sliding time window to filter out non-braking fluctuations caused by road surface excitation, making the adjustment step of the motor's negative torque anchored to the actual tire-road adhesion state. Through offline calibration procedures, this solution maintains the consistency of braking torque connection under different life cycle hydraulic hardware environments, limiting the fluctuation rate of the vehicle's braking intensity to within a physical error range of 2.1%, and achieving synergy between braking smoothness and energy recovery intensity.

[0050] Example 4: In the static initialization scenario after the vehicle completes final assembly or the braking mechanism hardware is replaced, the vehicle braking control system uses a static self-test procedure to establish a physical pressure reference at the brake wheel cylinder end and to establish a quantitative basis for the signal trust threshold. Under the condition of receiving a parking brake lock-up signal and the wheel speed pulse frequency being 0Hz for 5 seconds, the processor continuously reads 100 cycles of physical pressure data, calculates the arithmetic mean of the dataset as the sensor zero-point bias, and stores this mean in non-volatile memory as the initial compensation value for subsequent pressure differential calculation. Based on this, the system drives the hydraulic braking circuit to generate a preset pressure pulse with an amplitude of 0.5MPa, and monitors the pressure feedback signal to achieve a response delay time of 90% of the amplitude. Determine the window length coefficient for smoothing filtering. Window length coefficient Satisfying the relation ,in, This is the window length coefficient. In response to the delay time, Sampling frequency, The dynamic smoothing coefficient is determined by the real-time pressure build-up rate. The extraction provides preprocessing parameters.

[0051] When the vehicle braking control system is operating under braking conditions and the detected brake wheel cylinder pressure is kept constant, the processor updates the dynamic boundary of the signal trust threshold by monitoring the real-time variance fluctuation of the physical pressure data. The system extracts the pressure measurement residuals of 20 consecutive control cycles, calculates the background noise intensity under the current physical environment based on the residual distribution law, and superimposes it with 3 times the standard deviation as the updated signal trust threshold. This allows the statistical judgment logic of the sliding time window to adapt to changes in the electromagnetic compatibility environment. Under this operating procedure, if the detected real-time variance exceeds the signal trust threshold for 3 consecutive sampling cycles, the system triggers the sensor state anomaly judgment logic and automatically switches to the braking torque estimation mode based on the motor speed gradient until the real-time variance returns to the safe threshold range. In this way, the control stability of the dynamic constraint boundary is maintained throughout the entire life cycle through closed-loop monitoring of the hardware state, and the vehicle is in a smooth braking torque transition state under different hardware aging levels and environmental interference intensities.

[0052] Example 5: When the vehicle is operating under conditions of frequent switching of regenerative braking discontinuation and the processor switches to the braking torque estimation mode based on motor speed gradient due to the real-time variance exceeding the signal trust threshold, the system uses a confidence counting procedure to establish a criterion for determining the regression dynamic constraint boundary control mode. When the processor detects that the real-time variance has dropped below the signal trust threshold, it initiates the... The system uses a confidence regression window consisting of sampling periods to continuously monitor the gradient of statistical variance. If, within the confidence regression window, the maximum value of the statistical variance is consistently below 85% of the signal confidence threshold and the slope of its variance envelope is negative, the system reactivates the dynamic constraint boundary and adjusts the negative torque of the motor. The confidence counting procedure's counting threshold is then used. Satisfy the equation ,in, The confidence count threshold. The confidence recovery constant is... The sampling frequency is used to suppress the control switching caused by the transient recovery of sensor signals by setting a time-domain lag interval.

[0053] When a vehicle is traveling a long distance and the internal temperature of the hydraulic braking system deviates, causing a change in brake fluid volume, the vehicle braking control system executes a no-load zero-point recalibration procedure to suppress physical pressure drift. When the processor receives a no-load trigger signal indicating that the drive motor output torque is zero and the brake pedal displacement signal is zero, it collects physical pressure data for 50 consecutive control cycles and calculates the sliding average of the current reading. If the moving average If the absolute value of the deviation from the preset zero reference is within the range of 0.02MPa to 0.05MPa, the processor will use the current moving average. The reference zero-bias parameter for the physical zero position is determined and adjusted synchronously for the smoothing filter processing, where The determination procedure, which is the sliding average value of physical pressure, eliminates the spurious signal increments caused by environmental thermal stress by periodically capturing the steady-state pressure of the fluid pipeline. This ensures that the pressure sensing error of the hydraulic braking circuit under full-temperature conditions is kept below 0.05% of the full scale, thereby enabling the vehicle to maintain the linear response characteristics of braking torque transfer under different temperature gradient physical environments.

[0054] In scenarios where the vehicle's power battery is in a high state of charge and the drive motor is operating under high-speed, weak-field conditions, the processor reads the real-time bus voltage of the drive motor. With real-time speed Determine the real-time power generation limit during motor braking. The system pre-stores a two-dimensional feature map in non-volatile memory, consisting of bus voltage data ranging from 300V to 450V and speed gradients ranging from 0rpm to 15000rpm. The processor then obtains the current... and The real-time power generation limit under the current physical state is extracted within the two-dimensional feature map using a bilinear interpolation algorithm. According to the formula Real-time power generation limit Converted to the maximum regenerative torque at the current speed ,in, For the ultimate recovery torque, To determine the real-time power generation limit, For real-time speed, this calibration procedure establishes electromagnetic physical boundary limits for feedback regulation to allow the motor to exit negative torque.

[0055] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A vehicle braking feedback process for improving recovery rate, characterized in that, Includes the following steps: Step S1: Real-time acquisition of physical pressure data of the brake wheel cylinders in the vehicle braking circuit; Step S2: Retrieve the preset noise filtering threshold to smooth the physical pressure data, and calculate the rate of change of brake wheel cylinder pressure over time based on the filtered physical pressure data, so as to extract the real-time pressure build-up rate of the hydraulic brake circuit under the current ambient temperature. Step S3: Calculate the dynamic constraint boundary for the motor's negative torque withdrawal based on the real-time pressure build-up rate. Transform the hydrodynamic response characteristics of the hydraulic braking circuit into time-domain constraints for the motor's negative torque decay through the dynamic constraint boundary, so as to establish the nonlinear correlation constraint relationship between the motor's negative torque withdrawal gradient and the hydraulic braking circuit's pressure build-up gradient. Step S4: After receiving the brake energy recovery exit command, the wheel slip ratio deviation value is collected in real time, and the feedback adjustment of the motor negative torque is completed by combining the dynamic constraint boundary and the wheel slip ratio deviation value. Among them, when the real-time pressure build-up rate decreases due to the increase in brake fluid viscosity caused by the sudden change in ambient temperature, the nonlinear correlation constraint relationship limits the decrease slope of the motor negative torque through the dynamic constraint boundary, so that the withdrawal strength of the motor negative torque during the switching transient process is always limited to the actual effective pressure increment of the hydraulic braking circuit under the current pipeline physical state. In this way, the total braking torque drop into the vacuum zone is eliminated by offsetting the pressure build-up response delay of the hydraulic braking circuit, and the effective intervention time of electric brake recovery is extended to the physical boundary where the wheel slip ratio does not exceed the ground adhesion limit.

2. The vehicle braking feedback process for improving recovery rate according to claim 1, characterized in that, The process of constructing dynamic constraint boundaries in step S3 includes: obtaining the preset torque coupling coefficient and torque response step time parameters; using the real-time pressure build-up rate and torque coupling coefficient for linear mapping processing to calculate the maximum allowable decrease of the motor negative torque in the current control cycle; multiplying the maximum allowable decrease by the torque response step time parameters to define the hard slope constraint in the motor negative torque exit process.

3. The vehicle braking feedback process for improving recovery rate according to claim 1, characterized in that, In step S1, physical pressure data is acquired by monitoring pressure sensors located at the cylinder end of the brake wheel; in step S2, differential calculation is performed on the digital pressure values ​​of adjacent sampling periods, and the derivative of pressure with respect to time is calculated in combination with the sampling frequency, so as to capture the transient pressure build-up characteristics of the fluid inside the hydraulic braking circuit caused by the mechanical dead zone of the valve core or the obstruction of the pipeline in real time, thereby providing physical feedback for the calculation of dynamic constraint boundaries.

4. The vehicle braking feedback process for improving recovery rate according to claim 1, characterized in that, When completing the feedback adjustment of the motor negative torque in step S4, the following steps are also included: real-time monitoring of the bus voltage and real-time speed of the drive motor to determine the real-time power generation limit of the drive motor; when the exit rate defined by the dynamic constraint boundary is lower than the safe exit slope corresponding to the real-time power generation limit, the dynamic constraint boundary is used as the main control reference for adjustment to maintain the kinetic energy recovery intensity; if the dynamic constraint boundary reflects the stagnation of pressure growth, an early warning signal is output.

5. The vehicle braking feedback process for improving recovery rate according to claim 1, characterized in that, Before step S1, an initialization calibration step is also included: under the static condition of the vehicle, the hydraulic braking circuit is controlled to perform multiple pressure build-up cycle tests to obtain the pipeline response characteristic curves under different ambient temperatures; based on the pipeline response characteristic curves, the noise filtering threshold of the real-time pressure build-up rate is calibrated, and the noise filtering threshold is stored in the controller for smoothing the acquired raw signal in step S2 to eliminate system background noise.

6. The vehicle braking feedback process for improving recovery rate according to claim 1, characterized in that, In step S3, the nonlinear correlation constraint relationship also introduces a vehicle speed correction step, including: collecting the current longitudinal vehicle speed; querying the preset recovery weight mapping relationship table based on the current longitudinal vehicle speed to obtain the speed correction factor; using the speed correction factor to perform nonlinear weighting processing on the dynamic constraint boundary, and increasing the locking strength of the motor negative torque when the vehicle is in the high-speed range above 80km / h, so as to extend the time window for high-value kinetic energy recovery.

7. The vehicle braking feedback process for improving recovery rate according to claim 1, characterized in that, The process of obtaining the wheel slip ratio deviation value in step S4 includes: collecting the real-time angular velocity of each wheel through the wheel speed sensor; calculating the real-time slip ratio of each wheel in combination with the vehicle body reference speed; comparing the real-time slip ratio with the preset target recovery slip ratio range to calculate the wheel slip ratio deviation value, and using the wheel slip ratio deviation value as the proportional correction term for motor negative torque feedback adjustment.

8. The vehicle braking feedback process for improving recovery rate according to claim 2, characterized in that, The process of determining the torque coupling coefficient includes: real-time monitoring of the displacement change rate of the brake pedal; identifying the driver's real-time braking intensity requirement based on the displacement change rate; and increasing the value of the torque coupling coefficient when the real-time braking intensity requirement exceeds the preset value of 0.5g acceleration to shorten the exit time of the motor's negative torque and ensure that the hydraulic braking system can quickly take over to meet the emergency braking safety requirements.

9. The vehicle braking feedback process for improving recovery rate according to claim 1, characterized in that, After completing step S4, the following steps are also included: monitoring the actual attenuation of the motor's negative torque and the actual compensation of the brake wheel cylinder pressure; when the torque deviation between the actual attenuation and the actual compensation exceeds 5%, the attenuation gradient defined in step S3 is corrected in real time based on the torque deviation, and residual offset is achieved by adjusting the given current loop of the motor to realize the closed-loop smoothness of the vehicle's total braking torque at the handover of the electro-hydraulic power source.

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