A method, system, device and computer readable storage medium for determining braking force of a vehicle under steep slope working condition

Abstract

The application discloses a kind of vehicle under steep slope working condition brake force determination method, system, equipment and computer readable storage medium, the method comprises: if the parameter obtained meets preset steep slope braking condition, enter steep slope mode, and according to parameter and preset three-dimensional mapping model, the braking force distribution coefficient of front axle and rear axle is obtained, parameter includes environmental parameter and vehicle parameter;According to the total brake force demand received, the braking force distribution coefficient of front axle and rear axle, determine each wheel target brake force;According to each wheel target brake force, each wheel is executed brake operation.The application adjusts the braking force distribution coefficient of front axle and rear axle dynamically, so that it adapts to the axle load transfer characteristics under steep slope working condition, so as to improve brake efficiency and adhesion utilization rate, shorten brake distance, improve brake stability, while reducing the operating load of driver.

Description

Technical Field

[0001] This application relates to the field of vehicle braking, specifically to a method, system, device, and computer-readable storage medium for determining the braking force of a vehicle under steep slope conditions. Background Technology

[0002] Currently, with the rapid development of automotive drive-by-wire chassis technology, electro-mechanical braking systems (EMB), with their advantages of fast response, high control precision, and compact structure, are gradually replacing traditional hydraulic braking systems and electro-hydraulic braking systems, becoming an important development direction in the fields of intelligent driving and new energy vehicles. EMB systems eliminate traditional hydraulic lines, directly driving the brake calipers with a motor to generate clamping force, achieving completely independent, millisecond-level precise control of the braking force of all four wheels, providing a hardware foundation for the implementation of advanced braking control strategies. At the same time, vehicle driving conditions are becoming increasingly complex, and braking safety on steep slopes (including steep uphill and long downhill sections) has become a focus of attention in the field of braking control technology. Under steep slope conditions, the gravitational component caused by the slope leads to a significant transfer of vertical loads between the front and rear axles. How to match the braking force distribution with the dynamic axle load to improve braking efficiency and adhesion utilization has become a pressing technical requirement in the field of braking control technology.

[0003] In related technologies, Electronic Brake-force Distribution (EBD) systems typically pre-calibrate fixed or segmented fixed ratios of front and rear axle braking force distribution coefficients based on vehicle load conditions, and distribute the total braking force to the front and rear axles according to these fixed ratios during vehicle braking. This fixed-ratio distribution strategy can balance braking stability and braking efficiency under normal flat road conditions, and its control logic is simple and highly reliable, thus it has been widely used in vehicles with traditional hydraulic brakes. Traditional hydraulic braking systems rely on the master cylinder to establish hydraulic pressure, and then transmit the pressure to the brakes of each wheel through hydraulic lines to achieve service braking through the hydraulic circuit.

[0004] However, the aforementioned existing technical solutions have at least the following technical problems: Since the fixed-ratio EBD allocation coefficient is pre-calibrated based on flat roads or specific load conditions, it cannot be dynamically adjusted according to the axle load transfer caused by the slope under steep slope conditions. When the vehicle is traveling on a steep slope, the vertical loads of the front and rear axles change significantly due to the gravity component of the slope (load shifts backward and rear axle adhesion increases when going uphill; load shifts forward and front axle adhesion increases when going downhill), while the fixed-ratio allocation still outputs according to the coefficient calibrated on flat roads. This results in a mismatch between the actual braking force distribution and the current adhesion of each wheel: the braking force of some wheels exceeds their adhesion limit and tends to lock up, while the adhesion of other wheels is not fully utilized, causing a decrease in overall vehicle braking efficiency, insufficient adhesion utilization, and an extended braking distance, posing a safety hazard. Summary of the Invention

[0005] This application provides a method, system, device, and computer-readable storage medium for determining the braking force of a vehicle under steep slope conditions, which can solve the technical problems of low braking efficiency and insufficient adhesion utilization caused by axle load transfer in existing fixed-ratio EBD or traditional hydraulic braking systems under steep slope conditions.

[0006] In a first aspect, embodiments of this application provide a method for determining the braking force of a vehicle under steep slope conditions, the method comprising: If the obtained parameters are determined to meet the preset steep slope braking conditions, the steep slope mode is entered, and the braking force distribution coefficients of the front axle and the rear axle are obtained according to the parameters and the preset three-dimensional mapping model. The parameters include environmental parameters and vehicle parameters. Based on the received total braking force demand and the braking force distribution coefficients of the front and rear axles, the target braking force for each wheel is determined. Braking operations are performed on each wheel according to the target braking force of each wheel.

[0007] In conjunction with the first aspect, in one implementation, the environmental parameters include a slope value, the vehicle parameters include brake pedal force and vehicle speed, and the step of entering steep slope mode if the acquired parameters are determined to meet preset steep slope braking conditions includes: Determine whether the obtained slope value, brake pedal force, and vehicle speed meet the preset steep slope braking conditions; If the absolute value of the obtained slope value is greater than the preset slope threshold, the brake pedal force is greater than the preset force threshold, and the obtained vehicle speed is less than the vehicle speed at the previous moment, then it is determined that the preset steep slope braking conditions are met, and the steep slope mode is entered.

[0008] In conjunction with the first aspect, in one implementation, obtaining the braking force distribution coefficients of the front axle and rear axle based on the parameters and a preset three-dimensional mapping model includes: By obtaining the slope value and the preset three-dimensional mapping model, the baseline values ​​of the front and rear axle braking force distribution coefficients are obtained. The reference value is corrected for the first time based on the obtained vehicle speed to obtain the front axle and rear axle braking force distribution coefficients after the first correction. The front and rear axle braking force distribution coefficients, which have been corrected in the first correction, are then corrected a second time based on the obtained brake pedal force to obtain the final front and rear axle braking force distribution coefficients. The correction magnitudes of the first and second corrections do not exceed the preset correction limits.

[0009] In conjunction with the first aspect, in one implementation, determining the target braking force for each wheel based on the received total braking force demand and the braking force distribution coefficients of the front and rear axles includes: The total braking force requirement is determined by analyzing the obtained brake pedal force. According to the front axle and rear axle braking force distribution coefficients, the total braking force demand is distributed to the front axle and rear axle to obtain the target braking force of the front axle and the target braking force of the rear axle, respectively. Based on the obtained load status and road surface adhesion status of the left and right front wheels, the target braking force of the front axle is distributed to the left front wheel and the right front wheel; Based on the obtained load status and road surface adhesion status of the left and right rear wheels, the target braking force of the rear axle is distributed to the left and right rear wheels, thereby obtaining the target braking force of each wheel.

[0010] In conjunction with the first aspect, in one embodiment, after performing braking operations on each wheel according to the target braking force of each wheel, the method further includes: When the absolute value of the obtained slope is less than the preset exit slope threshold, or the brake pedal force is less than the preset exit force threshold, or the obtained vehicle speed is less than the preset vehicle speed threshold, the steep slope mode is exited. After exiting the steep slope mode, the braking force distribution coefficients of the front and rear axles are gradually reduced to the second preset distribution coefficient within a preset time period. Based on the received second total braking force demand and the second preset allocation coefficient, determine the second target braking force for each wheel; Braking is performed on each wheel according to the second target braking force of each wheel.

[0011] In conjunction with the first aspect, in one embodiment, before the braking force distribution coefficients of the front axle and rear axle gradually decrease to a second preset distribution coefficient within a preset time period, the method further includes: If an emergency braking event is detected during the gradual descent process, a preset emergency braking control strategy is executed to obtain a third preset allocation coefficient. The preset emergency braking control strategy includes at least terminating the gradual descent and reversing. Based on the received third total braking force demand and the third preset allocation coefficient, determine the third target braking force for each wheel; Braking is performed on each wheel based on the third target braking force described for each wheel.

[0012] In conjunction with the first aspect, in one embodiment, after performing braking operations on each wheel according to the target braking force of each wheel, the method further includes: Monitor the working status of each EMB actuator at a preset cycle; When a failure is detected in any EMB actuator, a reconfiguration allocation strategy is executed to allocate the target braking force to each wheel; The reconfiguration allocation strategy includes increasing the target braking force of the wheel on the same axle as the faulty wheel and the wheel on the other axle.

[0013] Secondly, embodiments of this application provide a system for determining the braking force of a vehicle under steep slope conditions, the system comprising: The working condition identification module is used to enter steep slope mode if the acquired parameters meet the preset steep slope braking conditions. The ratio determination module is used to obtain the braking force distribution coefficients of the front axle and the rear axle based on the parameters and the preset three-dimensional mapping model. The execution control module is used to determine the target braking force for each wheel based on the received total braking force demand and the braking force distribution coefficients of the front and rear axles; The braking execution module is used to perform braking operations on each wheel according to the target braking force of each wheel.

[0014] Thirdly, embodiments of this application provide a device for determining the braking force of a vehicle under steep slope conditions. The device for determining the braking force of a vehicle under steep slope conditions includes a processor, a memory, and a program for determining the braking force of a vehicle under steep slope conditions stored in the memory and executable by the processor. When the program for determining the braking force of a vehicle under steep slope conditions is executed by the processor, it implements the steps of the method for determining the braking force of a vehicle under steep slope conditions as described in any of the preceding claims.

[0015] Fourthly, embodiments of this application provide a computer-readable storage medium storing a program for determining the braking force of a vehicle under steep slope conditions. When the program for determining the braking force of a vehicle under steep slope conditions is executed by a processor, it implements the steps of the method for determining the braking force of a vehicle under steep slope conditions as described in any of the preceding claims.

[0016] The beneficial effects of the technical solutions provided in this application include: If the obtained parameters are determined to meet the preset steep slope braking conditions, the system enters the steep slope mode and obtains the braking force distribution coefficients of the front and rear axles based on the parameters and the preset three-dimensional mapping model. Based on the received total braking force demand and the braking force distribution coefficients of the front and rear axles, the target braking force of each wheel is determined. Braking operation is performed on each wheel according to the target braking force of each wheel. This solves the technical problems of low braking efficiency and insufficient adhesion utilization caused by axle load transfer in existing technologies based on fixed ratio EBD or traditional hydraulic braking systems under steep slope conditions. On the one hand, the braking force distribution coefficient is dynamically adjusted according to the slope value, so that the braking force of the front and rear axles matches the axle load distribution under steep slope conditions. This breaks through the bottleneck of fixed ratio distribution where adhesion is not fully utilized under axle load transfer conditions, and shortens the braking distance. On the other hand, the total braking force demand is analyzed in real time according to the brake pedal force, and the target braking force of each wheel is further distributed according to the differences in wheel load and adhesion state. This overcomes the defects of slow response and low precision of traditional hydraulic braking and improves braking stability. At the same time, the distribution coefficient is adjusted in real time with the slope, which reduces the driver's operating load and improves driving comfort. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the method for determining the braking force of the vehicle under steep slope conditions in this application. Figure 2 This is a schematic diagram of the functional modules of the braking force determination system for the vehicle under steep slope conditions in this application. Detailed Implementation

[0018] The method for determining the braking force of a vehicle under steep slope conditions, provided in this application embodiment, will be described in detail below with reference to the accompanying drawings and specific application scenarios.

[0019] In one possible implementation, see Figure 1 The flowchart shown illustrates the method for determining the braking force of a vehicle under steep slope conditions provided in this application embodiment. This method is executed by the vehicle control unit (VCU) or brake control unit (BCU) within the vehicle. The specific steps of this method are as follows.

[0020] S10, if the acquired parameters meet the preset steep slope braking conditions, the vehicle enters steep slope mode and obtains the braking force distribution coefficients for the front and rear axles based on the parameters and a preset three-dimensional mapping model. The parameters include environmental parameters and vehicle parameters. Environmental parameters include at least the slope value of the current slope the vehicle is on, which can be obtained through a slope sensor. Vehicle parameters include at least the brake pedal force applied by the driver and the vehicle's real-time speed. The brake pedal force can be obtained through a pedal displacement sensor or a pedal force sensor, and the real-time speed can be obtained through wheel speed sensors.

[0021] For example, the vehicle acquires in real time the slope value output by the slope sensor, the pedal travel output by the pedal displacement sensor or the pedal force output by the pedal force sensor, and the wheel speed signal output by the wheel speed sensor, and calculates the vehicle speed based on the wheel speed signal.

[0022] In one possible implementation, after acquiring the aforementioned parameters, the vehicle first determines the steep slope braking conditions based on these parameters. Specifically, when the absolute value of the acquired slope is greater than a preset entry slope threshold, the brake pedal force is greater than a preset force threshold, and the acquired vehicle speed is less than the vehicle speed at the previous moment, the vehicle determines that the preset steep slope braking conditions are met and enters steep slope mode.

[0023] For example, the preset entry slope threshold can be 8°, and the preset force threshold can be the force value corresponding to 5% of the pedal travel. The preset entry slope threshold and the preset force threshold can be calibrated according to the vehicle type and braking performance. For example, the preset entry slope threshold can be 6°, 8° or 10°, and the preset force threshold can be the force value corresponding to 3%, 5% or 8% of the pedal travel.

[0024] Furthermore, after the vehicle enters steep slope mode, based on the currently acquired parameters and a preset 3D mapping model, the braking force distribution coefficients for the front and rear axles are obtained. The braking force distribution coefficients are... The ratio of rear axle braking force to total vehicle braking force, i.e. The three-dimensional mapping model is pre-generated based on real vehicle calibration data. It takes the slope value, current vehicle speed and brake pedal force as input and outputs the braking force distribution coefficients of the front axle and rear axle under the current working conditions.

[0025] In one possible implementation, the process of obtaining the braking force distribution coefficients of the front and rear axles based on parameters and a preset three-dimensional mapping model may include the following steps: obtaining baseline values ​​for the braking force distribution coefficients of the front and rear axles using the obtained slope value and the preset three-dimensional mapping model; performing a first correction on the baseline values ​​based on the obtained vehicle speed to obtain the first-corrected braking force distribution coefficients of the front and rear axles; and performing a second correction on the first-corrected braking force distribution coefficients of the front and rear axles based on the obtained brake pedal force to obtain the final braking force distribution coefficients of the front and rear axles. The correction ranges for both the first and second corrections do not exceed preset correction limits.

[0026] In one possible implementation, the formula for calculating the final allocation coefficient is: ;in, This is the baseline value corresponding to the slope value θ. This is the correction amount corresponding to the vehicle speed v. This is the correction amount corresponding to the brake pedal force *s*; simultaneously, physical upper and lower limit constraints are set for all operating conditions. ,in, This is the minimum braking force distribution coefficient. The maximum braking force distribution coefficient is set to ensure that the wheel adhesion limit is not exceeded. For example, the benchmark value The value range is 0.20≤ ≤0.60, its trend with the slope value θ is as follows: when driving uphill (θ>0). It increases monotonically as θ increases; when driving downhill (θ<0). It decreases monotonically as the absolute value of θ increases; in the flat road transition zone (-6°≤θ≤+6°), the flat road reference value (e.g., 0.40) is maintained.

[0027] Optionally, the benchmark value Alternatively, it can be obtained through actual vehicle calibration. The calibration method is as follows: On a slope with a gradient of θ, conduct braking tests with different front and rear axle distribution coefficients, record the slip ratio of each wheel and the deceleration of the whole vehicle, and select the distribution coefficient that makes the front and rear axle wheels close to locking at the same time and the deceleration of the whole vehicle is the largest as the optimal reference value under that slope.

[0028] For example, vehicle speed correction amount The determination method is a combination of table lookup and linear interpolation. A calibration example is as follows: when the vehicle speed v = 0 km / h, Δβ_speed = +0.02; when v = 30 km / h, =+0.01; When v=60km / h, Δβ_speed=0; When v=90km / h, =-0.01; when v=120km / h, d=-0.02; when v=150km / h, =-0.025; when v=180km / h, =-0.03; For speed values ​​not listed, linear interpolation is used to obtain the corresponding correction. That is, the speed correction. The value range is limited to the interval [-0.03, +0.02].

[0029] For example, brake pedal force correction amount The determination method is a combination of table lookup and linear interpolation. A calibration example is as follows: when the brake pedal force s = 0%, =+0.02; When s=10%, =+0.015; when s=30% =+0.01; When s=50%, l=0; when s=70% =-0.01; when s=90%, =-0.02; when s=100%, =-0.03. For brake pedal force values ​​not listed in the table, linear interpolation is used to obtain the corresponding correction. That is, the brake pedal force correction. The value range is limited to the interval [-0.03, +0.02].

[0030] For example, the calibration basis for the preset correction limit is: to ensure that the correction of the distribution coefficient does not change the overall distribution trend dominated by the slope, while taking into account the comprehensive requirements of braking stability and braking efficiency. Since excessive correction may cause the front and rear axle braking force distribution to deviate significantly from the optimal ratio under slope conditions, leading to instability risks such as rear axle lock-up first or front axle lock-up prematurely, the correction range is limited to within ±0.03. This limit is obtained by comprehensively calibrating based on the vehicle's braking stability requirements, the safety margin of wheel adhesion limits, and the intervention threshold of the anti-lock braking system. For example, the first correction limit and the second correction limit can be equal, for example, both ±0.03; or they can be differentiated according to the vehicle type.

[0031] The priority of the three factors, from highest to lowest, is as follows: gradient θ factor > brake pedal force s factor > vehicle speed v factor. Lower priority factors can only make minor adjustments within the baseline range of higher priority factors and must not reverse the overall allocation trend. Specifically: (1) The gradient is the dominant factor. The static axle load transfer caused by the gradient is the core factor determining the upper limit of the front and rear axle adhesion. The amount of transfer is positively correlated with the gradient. When driving uphill (θ>0), the static axle load is transferred to the rear axle. The greater the gradient, the higher the upper limit of the rear axle adhesion. Therefore, the benchmark... It monotonically increases with increasing θ. When driving downhill (θ<0), the static axle load shifts to the front axle. The steeper the slope, the lower the upper limit of the rear axle adhesion. Therefore, the baseline value β_base monotonically decreases with increasing absolute value of θ. In the transition zone on flat roads (e.g., -6°≤θ≤+6°), the baseline value is maintained to avoid frequent adjustments to the distribution coefficient caused by small road surface undulations. This factor determines the overall range and adjustment direction of β, and no correction factor should reverse the slope-dominated distribution trend.

[0032] (2) Speed ​​correction rules: Vehicle speed does not directly change axle load, but it affects the risk level of rear axle lock-up: At high speeds, rear axle lock-up is prone to causing severe fishtailing, requiring a high stability margin and a moderate reduction in the rear axle ratio; At low speeds, the risk of rear axle lock-up is low, and the rear axle ratio can be moderately increased to optimize braking efficiency. The adjustment logic is consistent whether going uphill or downhill: the higher the vehicle speed, the lower the risk of rear axle lock-up. The smaller the size, the more the rear axle ratio is adjusted downwards, prioritizing driving stability; the lower the vehicle speed, the better. The larger the value, the more the rear axle ratio is adjusted, prioritizing improved braking efficiency; the speed correction range does not exceed the preset correction limit, for example, strictly controlled within ±0.03, so as not to affect the core distribution logic.

[0033] (3) Brake pedal force correction law: The brake pedal force corresponds to the braking intensity required by the driver. Braking deceleration will cause dynamic axle load to shift forward. The greater the braking intensity, the greater the dynamic axle load shifts forward, and the actual load on the rear axle is relatively reduced. The distribution coefficient needs to be finely adjusted in the opposite direction. The adjustment logic is the same whether going uphill or downhill: the greater the brake pedal force (the higher the braking intensity). The smaller the value, the more the rear axle ratio is adjusted downwards to offset the effect of dynamic axle load shifting forward; the smaller the brake pedal force (the lower the braking intensity). The larger the value, the higher the rear axle ratio should be, so as to make full use of the static axle load characteristics to improve braking efficiency. The correction range of the brake pedal force correction should not exceed the preset correction limit, for example, strictly controlled within ±0.03, and only slightly adjusted near the slope reference, without changing the overall distribution trend.

[0034] Optionally, under low-adhesion road surface conditions, if the road surface adhesion coefficient is identified to be less than 0.4 (such as icy and snowy roads), it can be reduced... The value is used to lower the upper limit of the proportion of braking force on the rear axle.

[0035] Optionally, the allocation coefficients change continuously with the input parameters without any abrupt breaks, so as to ensure that the braking process is smooth and without abruptness, that is, the three-dimensional mapping model satisfies the smoothness constraint.

[0036] S20 determines the target braking force for each wheel based on the received total braking force demand and the braking force distribution coefficients of the front and rear axles.

[0037] Specifically, the total braking force requirement is determined as follows: based on the obtained brake pedal force, the driver's requested total braking force requirement is obtained by analyzing the preset brake pedal force-total braking force requirement characteristic curve; wherein, the brake pedal force-total braking force requirement characteristic curve is a monotonically increasing function, that is, the greater the brake pedal force, the greater the total braking force requirement.

[0038] Furthermore, the process of determining the target braking force for each wheel may include the following steps: First, according to the front and rear axle braking force distribution coefficients, the total braking force demand is distributed to the front and rear axles, respectively, yielding the target braking force for the front axle and the target braking force for the rear axle. The target braking force for the front axle is equal to the total braking force demand multiplied by (1 - braking force distribution coefficient). The target braking force of the rear axle is equal to the total braking force demand multiplied by the braking force distribution coefficient. ; Then, based on the obtained load states and road surface adhesion states of the left and right front axle wheels, where the load of each wheel is obtained through a suspension height sensor and the adhesion state is obtained through a road surface adhesion coefficient estimation algorithm or a wheel slip ratio observer, the target braking force of the front axle is distributed to the left and right front wheels; similarly, based on the obtained load states and road surface adhesion states of the left and right rear axle wheels, the target braking force of the rear axle is distributed to the left and right rear wheels, thereby obtaining the target braking force of each wheel.

[0039] Specifically, when a vehicle is tilted on a slope or experiences lateral acceleration, the loads on the left and right wheels are different, and the adhesion conditions are also different. In order to make full use of the adhesion of each wheel, more braking force is distributed to the wheel with a larger load and better adhesion conditions.

[0040] For example, when the load on the left front wheel is greater than the load on the right front wheel, the proportion of the target braking force distributed to the left front wheel on the front axle can be greater than that on the right front wheel. When the loads on the left and right front wheels are equal, the proportions of the target braking force distributed to the left and right front wheels on the front axle can be equal.

[0041] S30 performs braking operations on each wheel according to the target braking force of each wheel.

[0042] Specifically, the target braking force (i.e., target clamping force) command for each wheel is sent to the corresponding EMB actuator. After receiving the command, the motor controller inside each EMB actuator controls the brake caliper to apply clamping force to the brake disc through a current-position-clamping force three-loop control algorithm, generating a braking torque that matches the target braking force, thereby achieving precise braking of each wheel.

[0043] In this embodiment, due to the independent control architecture of the four-wheel EMB, the braking force of each wheel can be adjusted independently. Therefore, the above allocation strategy can be executed precisely at the millisecond level, achieving rapid dynamic adjustment of the ratio.

[0044] Based on the method provided in the above embodiments of this application, when a vehicle is on a steep slope, it can dynamically adjust the braking force distribution coefficient between the front and rear axles by sensing parameters such as slope, vehicle speed, and brake pedal force, so as to adapt to the axle load transfer characteristics under steep slope conditions, thereby improving braking efficiency and braking stability. At the same time, by controlling the independent execution of each wheel, the adhesion of each wheel can be fully utilized, the braking distance can be shortened, and driving safety can be improved.

[0045] In one possible implementation, after performing braking operations on each wheel according to the target braking force of each wheel in step S30 above, the method further includes the steps of exiting the steep slope mode and smooth transition, specifically including the following steps.

[0046] The steep slope mode will exit when the absolute value of the obtained slope is less than the preset exit slope threshold, or the brake pedal force is less than the preset exit force threshold, or the obtained vehicle speed is less than the preset vehicle speed threshold.

[0047] For example, the preset exit slope threshold can be lower than the preset entry slope threshold to create a hysteresis range and prevent frequent mode switching. For instance, the preset entry slope threshold can be 8°, the preset exit slope threshold can be 6°, and the preset force threshold can be the force value corresponding to 2% of the pedal travel. The preset vehicle speed threshold can be 3 km / h, indicating that the vehicle is approaching a stop. After exiting the steep slope mode, the braking force distribution coefficient of the front and rear axles gradually decreases to the second preset distribution coefficient within a preset time period. The second preset distribution coefficient is the distribution coefficient under flat road conditions, for example, it can be 0.4. The preset time period can be between 200 and 500 milliseconds, for example, 200 milliseconds, 300 milliseconds or 500 milliseconds. During the gradual decrease, the distribution coefficient changes according to a linear or S-shaped curve to avoid braking shock and sudden change in body feeling caused by abrupt changes in the distribution coefficient. Then, based on the received second total braking force demand and the second preset allocation coefficient, the second target braking force of each wheel is determined. The second total braking force demand is the total braking force demand obtained by analyzing the current brake pedal force after exiting the steep slope mode. The method for determining the second target braking force of each wheel is the same as the method in step S20 above, and will not be repeated here. Finally, braking operations are performed on each wheel based on the second target braking force of each wheel. Through the above-mentioned gradual transition mechanism, a smooth switch between steep slope mode and normal mode is achieved, improving driving comfort.

[0048] Optionally, when the slope drops below 6°, or when accelerator pedal operation is detected, or when brake pedal is fully released, the steep slope mode is exited. The duration of the gradual transition of the distribution coefficient during the switching process can be set to 200 to 500 milliseconds to avoid braking shock and sudden changes in body feel.

[0049] In one possible implementation, before the braking force distribution coefficients of the front and rear axles gradually decrease to a second preset distribution coefficient within a preset time period, the method further includes an emergency braking processing step, specifically comprising the following steps: If an emergency braking event is detected during the gradual descent, a preset emergency braking control strategy is executed to obtain a third preset allocation coefficient. An emergency braking event can be triggered in any of the following ways: the rate of change of brake pedal force per unit time exceeds a preset emergency change rate threshold (e.g., 80% travel / second); or a high collision risk level is detected by a perception sensor, which can be a front radar, camera, or lidar, etc. The preset emergency braking control strategy includes at least: terminating the current gradual change process and reverting based on a preset emergency braking target coefficient value. Reverting means abandoning the gradual change towards the second preset allocation coefficient and instead locking or jumping to the allocation state corresponding to the third preset allocation coefficient. The third preset allocation coefficient can be maintaining the high front axle allocation ratio before exiting or a preset fixed value.

[0050] In one possible implementation, the emergency braking control strategy includes the following processing methods based on different transition directions during the gradual descent process: When the transition direction is from normal mode to steep slope mode, that is, the distribution coefficient is decreasing, if an emergency braking event is detected, the gradual change is immediately terminated, and the change is directly stepped to the target distribution coefficient (including the brake pedal force correction) corresponding to the current slope plus the current brake pedal force. This processing method can quickly reduce the rear axle ratio, match the axle load forward shift characteristics under high braking intensity, and avoid rear axle lock-up.

[0051] When switching from steep slope mode to normal mode, i.e. the distribution coefficient is in the process of recovering, if an emergency braking event is detected, the gradual change is immediately terminated and the mode is reversed. The distribution coefficient returns to the steady-state target value of steep slope mode, and the brake pedal force correction is added at the same time to temporarily delay exiting steep slope mode. This processing method can prevent the rear axle ratio from being too high during the exit process and avoid causing fishtailing under high braking intensity. When the transition direction is from the normal mode to the steep uphill mode, i.e., the distribution coefficient is increasing, if an emergency braking event is detected, the gradual transition is immediately terminated, and the system jumps directly to the target distribution coefficient corresponding to the current slope to fully utilize the rear axle adhesion and improve braking efficiency. This approach can quickly release the rear axle braking potential and shorten the uphill braking distance. When transitioning from uphill steep slope mode to normal mode, i.e., the distribution coefficient is decreasing, if an emergency braking event is detected, the transition is immediately terminated and reversed, returning to the steady-state distribution coefficient of uphill mode. This approach avoids premature front wheel lock-up due to excessively high front axle proportion and insufficient load, thus preserving steering capability.

[0052] Optionally, after the emergency braking is released, the system can resume a smooth transition to the second preset allocation coefficient at the original rate, starting from the current allocation coefficient.

[0053] Then, based on the received third total braking force demand and the third preset allocation coefficient, the third target braking force for each wheel is determined. The third total braking force demand is the total braking force demand during emergency braking, which can be the total braking force demand obtained from the analysis of extreme brake pedal force, or the total braking force demand requested by the automatic emergency braking system. Finally, braking operations are performed on each wheel according to the third target braking force of each wheel. Through the above emergency braking handling strategy, it is ensured that if the vehicle faces a sudden danger before it has fully returned to normal mode, it can still maintain maximum braking efficiency and stability.

[0054] In one possible implementation, after performing braking operations on each wheel according to the target braking force of each wheel in step S30 above, the method further includes a failure-tolerant reconstruction step, which specifically includes the following steps.

[0055] The operating status of each EMB actuator is monitored at a preset cycle. The operating status of each EMB actuator can include motor current, temperature, clamping force feedback value, and fault diagnostic codes. The vehicle can obtain the operating status of each EMB actuator in real time through the Controller Area Network (CAN) bus.

[0056] When a failure is detected in any EMB actuator, a reconfiguration allocation strategy is executed. The reconfiguration allocation strategy includes increasing the target braking force of the wheel on the same axle as the failed wheel and increasing the target braking force of the wheel on the other axle.

[0057] Specifically, when a fault is detected in the left front wheel actuator, the system prioritizes increasing the target braking force on the right front wheel to maintain lateral torque balance on the front axle and prevent vehicle deviation. The coaxial compensation amount should be limited by the wheel's adhesion limit and the motor's overload capacity. If the coaxial compensation is insufficient to compensate for the total braking force loss, the system simultaneously increases the target braking force on both rear axle wheels to ensure the vehicle deceleration meets the driver's request. Optionally, after reconfiguration, the system can monitor the slip ratio of each healthy wheel in real time. If the Anti-lock Braking System (ABS) or Electronic Stability Control (ESC) is triggered, vehicle stability control is prioritized, and the satiation of the driver's braking intentions is appropriately reduced to ensure driving safety.

[0058] The method embodiments provided by this application have been described above. The system embodiments provided by this application will be described below. It should be understood that the description of the system embodiments corresponds to the description of the method embodiments. Therefore, for content not described in detail, please refer to the method embodiments above. For the sake of brevity, it will not be repeated here.

[0059] See Figure 2 This application provides a system for determining the braking force of a vehicle under steep slope conditions. The system includes a condition identification module, a proportion determination module, an execution control module, and a braking execution module. The condition identification module is used to enter steep slope mode if the acquired parameters meet preset steep slope braking conditions. The proportion determination module is used to obtain the braking force distribution coefficients of the front and rear axles based on the parameters and a preset three-dimensional mapping model. The execution control module is used to determine the target braking force for each wheel based on the received total braking force demand and the braking force distribution coefficients of the front and rear axles. The braking execution module is used to perform braking operations on each wheel according to the target braking force for each wheel.

[0060] Optionally, in one possible implementation, the environmental parameters include a slope value, and the vehicle parameters include brake pedal force and vehicle speed. The condition recognition module is specifically used to: determine whether the acquired slope value, brake pedal force, and vehicle speed meet the preset steep slope braking conditions; if the absolute value of the acquired slope value is greater than a preset slope entry threshold, and the brake pedal force is greater than a preset force threshold, and the acquired vehicle speed is less than the vehicle speed at the previous moment, then it is determined that the preset steep slope braking conditions are met, and the vehicle enters steep slope mode.

[0061] Optionally, in one possible implementation, the ratio determination module is specifically used to: obtain a reference value for the front and rear axle braking force distribution coefficients by using the acquired slope value and a preset three-dimensional mapping model; perform a first correction on the reference value based on the acquired vehicle speed to obtain the first-corrected front and rear axle braking force distribution coefficients; and perform a second correction on the first-corrected front and rear axle braking force distribution coefficients based on the acquired brake pedal force to obtain the final front and rear axle braking force distribution coefficients. The correction magnitudes of both the first and second corrections do not exceed preset correction limits.

[0062] Optionally, in one possible implementation, the execution control module is specifically used to: analyze the total braking force demand based on the obtained brake pedal force; allocate the total braking force demand to the front axle and rear axle according to the front axle and rear axle braking force distribution coefficients, thereby obtaining the target braking force of the front axle and the target braking force of the rear axle respectively; allocate the target braking force of the front axle to the left front wheel and the right front wheel according to the obtained load state and road surface adhesion state of the left and right wheels of the front axle; and allocate the target braking force of the rear axle to the left rear wheel and the right rear wheel according to the obtained load state and road surface adhesion state of the left and right wheels of the rear axle, thereby obtaining the target braking force of each wheel.

[0063] Optionally, in one possible implementation, the system further includes a mode exit module, used to: exit the steep slope mode when the absolute value of the acquired slope value is less than a preset exit slope threshold, or the brake pedal force is less than a preset exit force threshold, or the acquired vehicle speed is less than a preset vehicle speed threshold; and control the braking force distribution coefficients of the front axle and rear axle to gradually decrease to a second preset distribution coefficient within a preset time period; determine the second target braking force for each wheel based on the received second total braking force demand and the second preset distribution coefficient; and perform braking operations on each wheel based on the second target braking force of each wheel.

[0064] Optionally, in one possible implementation, the system further includes an emergency braking module, configured to: if an emergency braking event is detected during the gradual descent, execute a preset emergency braking control strategy to obtain a third preset allocation coefficient, wherein the preset emergency braking control strategy includes at least terminating the gradual descent and reversing; determine a third target braking force for each wheel based on the received third total braking force demand and the third preset allocation coefficient; and perform braking operations on each wheel based on the third target braking force of each wheel.

[0065] Optionally, in one possible implementation, the system further includes a failure-tolerant module for: monitoring the operating status of each EMB actuator at a preset period; and when a failure is detected in any EMB actuator, executing a reconfiguration allocation strategy to allocate target braking forces to each wheel; wherein the reconfiguration allocation strategy includes: increasing the target braking forces of the wheel on the same axle as the failed wheel and the wheel on another axle.

[0066] Optionally, in one possible implementation, the system also includes a pedal force-feel matching module, which is used to synchronously adjust the force-stroke characteristics of the brake pedal simulator after entering the steep slope braking mode, so as to maintain the linear correspondence between the pedal force and the total braking force, ensure the consistency of the driver's braking feel, and allow him to operate without changing his habits.

[0067] It should be understood that the description of the system embodiments can refer to the relevant descriptions of the various method embodiments above. The implementation principle and technical effect are similar to those of the method embodiments above, and will not be repeated here.

[0068] It should also be understood that "modules" in a system can be implemented in hardware, software, or by hardware executing corresponding software. For example, a "module" can refer to an application-specific integrated circuit (ASIC), electronic circuitry, a processor (e.g., a shared processor, a proprietary processor, or a group processor) and memory for executing one or more software or firmware programs, integrated logic circuitry, and / or other suitable components that support the described functionality.

[0069] Based on the methods provided in the above embodiments, the embodiments of this application also provide the following content.

[0070] This application provides a device for determining the braking force of a vehicle under steep slope conditions. The device includes a processor, a memory, and a computer program stored in the memory and executable by the processor. When executed by the processor, the computer program implements the steps of the method for determining the braking force of a vehicle under steep slope conditions shown in the various embodiments above. Optionally, the device can be a vehicle controller or a brake control unit. The device may also include a communication interface for communicating with sensor modules, a brake pedal simulator, and various EMB actuators.

[0071] This application provides a computer-readable storage medium storing a computer program that, when run on a computer, causes the computer to perform the various steps or processes performed by the vehicle in any of the above method embodiments.

[0072] This application provides a chip including a memory and a processor. The processor executes a computer program stored in the memory to control the vehicle to perform the method for determining the braking force of the vehicle under steep slope conditions shown in the above embodiments.

[0073] It should be understood that the processor mentioned in the embodiments of this application can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0074] It should also be understood that the memory mentioned in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and Direct Rambus RAM (DR RAM).

[0075] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. In the above embodiments, the descriptions of each embodiment have different focuses; parts not described in detail or recorded in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0076] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0077] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between devices or units through some interfaces, and may be electrical, mechanical, or other forms.

[0078] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0079] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0080] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0081] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0082] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0083] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for determining the braking force of a vehicle under steep slope conditions, characterized in that, The method for determining the braking force of the vehicle under steep slope conditions includes: If the obtained parameters are determined to meet the preset steep slope braking conditions, the steep slope mode is entered, and the braking force distribution coefficients of the front axle and the rear axle are obtained according to the parameters and the preset three-dimensional mapping model. The parameters include environmental parameters and vehicle parameters. Based on the received total braking force demand and the braking force distribution coefficients of the front and rear axles, the target braking force for each wheel is determined. Braking operations are performed on each wheel according to the target braking force of each wheel.

2. The method for determining the braking force of a vehicle under steep slope conditions according to claim 1, characterized in that, The environmental parameters include slope value, and the vehicle parameters include brake pedal force and vehicle speed. If the acquired parameters are determined to meet preset steep slope braking conditions, then the steep slope mode is entered, including: Determine whether the obtained slope value, brake pedal force, and vehicle speed meet the preset steep slope braking conditions; If the absolute value of the obtained slope value is greater than the preset slope threshold, the brake pedal force is greater than the preset force threshold, and the obtained vehicle speed is less than the vehicle speed at the previous moment, then it is determined that the preset steep slope braking conditions are met, and the steep slope mode is entered.

3. The method for determining the braking force of a vehicle under steep slope conditions according to claim 1, characterized in that, The step of obtaining the braking force distribution coefficients of the front axle and rear axle based on the parameters and the preset three-dimensional mapping model includes: By obtaining the slope value and the preset three-dimensional mapping model, the baseline values ​​of the front and rear axle braking force distribution coefficients are obtained. The reference value is corrected for the first time based on the obtained vehicle speed to obtain the front axle and rear axle braking force distribution coefficients after the first correction. The front and rear axle braking force distribution coefficients, which have been corrected in the first correction, are then corrected a second time based on the obtained brake pedal force to obtain the final front and rear axle braking force distribution coefficients. The correction magnitudes of the first and second corrections do not exceed the preset correction limits.

4. The method for determining the braking force of a vehicle under steep slope conditions according to claim 1, characterized in that, The step of determining the target braking force for each wheel based on the received total braking force demand and the braking force distribution coefficients of the front and rear axles includes: The total braking force requirement is determined by analyzing the obtained brake pedal force. According to the front axle and rear axle braking force distribution coefficients, the total braking force demand is distributed to the front axle and rear axle to obtain the target braking force of the front axle and the target braking force of the rear axle, respectively. Based on the obtained load status and road surface adhesion status of the left and right front wheels, the target braking force of the front axle is distributed to the left front wheel and the right front wheel; Based on the obtained load status and road surface adhesion status of the left and right rear wheels, the target braking force of the rear axle is distributed to the left and right rear wheels, thereby obtaining the target braking force of each wheel.

5. The method for determining the braking force of a vehicle under steep slope conditions according to claim 1, characterized in that, After performing braking operations on each wheel according to the target braking force of each wheel, the method further includes: When the absolute value of the obtained slope is less than the preset exit slope threshold, or the brake pedal force is less than the preset exit force threshold, or the obtained vehicle speed is less than the preset vehicle speed threshold, the steep slope mode is exited. After exiting the steep slope mode, the braking force distribution coefficients of the front and rear axles are gradually reduced to the second preset distribution coefficient within a preset time period. Based on the received second total braking force demand and the second preset allocation coefficient, determine the second target braking force for each wheel; Braking is performed on each wheel according to the second target braking force of each wheel.

6. The method for determining the braking force of a vehicle under steep slope conditions according to claim 5, characterized in that, Before the braking force distribution coefficients of the front and rear axles gradually decrease to the second preset distribution coefficient within a preset time period, the method further includes: If an emergency braking event is detected during the gradual descent process, a preset emergency braking control strategy is executed to obtain a third preset allocation coefficient. The preset emergency braking control strategy includes at least terminating the gradual descent and reversing. Based on the received third total braking force demand and the third preset allocation coefficient, determine the third target braking force for each wheel; Braking is performed on each wheel based on the third target braking force described for each wheel.

7. The method for determining the braking force of a vehicle under steep slope conditions according to claim 1, characterized in that, After performing braking operations on each wheel according to the target braking force of each wheel, the method further includes: Monitor the working status of each EMB actuator at a preset cycle; When a failure is detected in any EMB actuator, a reconfiguration allocation strategy is executed to allocate the target braking force to each wheel; The reconfiguration allocation strategy includes increasing the target braking force of the wheel on the same axle as the faulty wheel and the wheel on the other axle.

8. A system for determining the braking force of a vehicle under steep slope conditions, characterized in that, The system includes: The working condition identification module is used to enter steep slope mode if the acquired parameters meet the preset steep slope braking conditions. The ratio determination module is used to obtain the braking force distribution coefficients of the front axle and the rear axle based on the parameters and the preset three-dimensional mapping model. The execution control module is used to determine the target braking force for each wheel based on the received total braking force demand and the braking force distribution coefficients of the front and rear axles; The braking execution module is used to perform braking operations on each wheel according to the target braking force of each wheel.

9. A device for determining the braking force of a vehicle under steep slope conditions, characterized in that, The device for determining the braking force of a vehicle under steep slope conditions includes a processor, a memory, and a program for determining the braking force of a vehicle under steep slope conditions stored in the memory and executable by the processor, wherein when the program for determining the braking force of a vehicle under steep slope conditions is executed by the processor, it implements the steps of the method for determining the braking force of a vehicle under steep slope conditions as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a program for determining the braking force of a vehicle under steep slope conditions, wherein when the program for determining the braking force of a vehicle under steep slope conditions is executed by a processor, it implements the steps of the method for determining the braking force of a vehicle under steep slope conditions as described in any one of claims 1 to 7.

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