Nod suppression method for AEB system close to parking

Abstract

The invention relates to the technical field of auxiliary driving active safety, and particularly discloses a nodding suppression method used when an AEB system is close to parking, and the nodding suppression method comprises the steps that in the braking process of the AEB system, the vehicle speed of a vehicle and the deceleration of current braking are obtained in real time; calculating to obtain predicted parking time and predicted parking distance according to the vehicle speed and the deceleration; when the predicted parking time reaches a preset parking time threshold value or the predicted parking distance reaches a preset parking distance threshold value, a nodding suppression function is activated, the wheel speed and the vehicle body acceleration of the vehicle are collected in real time, and the actual deceleration is calculated according to the wheel speed and the vehicle body acceleration; dynamically adjusting the braking torque output by the controller according to the actual deceleration and the preset target deceleration; the preset target deceleration is a dynamic value related to the vehicle speed. On the premise that the AEB collision safety performance is guaranteed, the comfort experience of passengers is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of driver assistance technology, and more specifically to a method for suppressing head nodding when an AEB system is about to stop. Background Technology

[0002] As a core feature in the field of automotive active safety, the Automatic Emergency Braking (AEB) system uses sensors such as radar and cameras to monitor the risk of collision ahead. When the driver does not intervene in time, the system automatically triggers a large deceleration braking to shorten the braking distance and achieve the purpose of avoiding or mitigating collision damage.

[0003] However, the control objective of existing AEB systems is primarily focused on "collision avoidance," that is, quickly establishing sufficient braking force to ensure braking effectiveness until the danger is eliminated or the vehicle comes to a complete stop. This control method results in significant deficiencies in the near-stop phase (typically referring to the process from when the vehicle speed falls below a certain threshold, such as 5 km / h, until it comes to a complete stop): the system maintains high braking pressure, causing the front suspension to compress and the rear suspension to extend, resulting in excessive pitching of the front of the vehicle and a significant "nose-diving" phenomenon (i.e., an increased pitch angle of the vehicle body around its lateral axis). This phenomenon not only reduces the comfort of passengers (e.g., forward head tilting, body jolting), but may also lead to cargo shifting (in commercial vehicle scenarios), and even affect braking stability in extreme cases (e.g., a sudden increase in front wheel load leading to decreased steering agility).

[0004] Currently, there are indeed some technical solutions on the market to address the brake dive problem, but these solutions are not optimized for special emergency situations like AEB that are not initiated by the driver.

[0005] Therefore, there is an urgent need for a method that can utilize environmental and vehicle attitude sensors without compromising AEB braking safety. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a method for suppressing nose-diving in AEB systems near a stop, specifically to solve the problem of severe nose-diving caused by the continuous and rapid release of braking force in existing AEB systems as the vehicle approaches a complete stop. This method introduces a smooth braking force attenuation strategy based on multi-parameter fusion at the end of the AEB braking process (i.e., the near-stop phase), effectively suppressing excessive nose-diving of the front of the vehicle, thereby improving the comfort of the emergency braking process while ensuring that the safety braking performance of AEB is not affected.

[0007] This invention provides a method for suppressing nose-diving in an AEB system when approaching a stop, comprising: During the AEB system braking process, the vehicle speed and current braking deceleration are acquired in real time; The predicted parking time and predicted parking distance are calculated based on the vehicle speed and the deceleration. When the predicted parking time reaches a preset parking time threshold or the predicted parking distance reaches a preset parking distance threshold, the head-nodding suppression function is activated, and the wheel speed and body acceleration of the vehicle are collected in real time. The actual deceleration is calculated based on the wheel speed and body acceleration. The braking torque output by the controller is dynamically adjusted based on the actual deceleration and the preset target deceleration; the preset target deceleration is a dynamic value related to the vehicle speed.

[0008] One possible implementation also includes: If any preset scenario is detected during the activation of the head-nodding suppression function, the head-nodding suppression function will be deactivated.

[0009] In one possible implementation, the preset scenario includes: receiving a signal that the AEB system has actively exited.

[0010] In one possible implementation, the preset scenario further includes receiving a signal that the driver has pressed the accelerator pedal.

[0011] In one possible implementation, the preset scenario further includes: receiving a signal that the driver has pressed the brake pedal and the requested braking force is greater than the force currently applied by the system.

[0012] In one possible implementation, the preset scenario includes at least: receiving a signal indicating an abnormal vehicle status.

[0013] In one possible implementation, the step of dynamically adjusting the braking torque output by the controller based on the actual deceleration and the preset target deceleration includes: The error is calculated based on the difference between the actual deceleration and the preset target deceleration; The braking torque is output by the PID algorithm and the error adjustment controller.

[0014] In one possible implementation, the step of dynamically adjusting the braking torque output by the controller based on the actual deceleration and the preset target deceleration includes: When the vehicle speed is less than the first preset vehicle speed, a first preset value is determined based on the vehicle speed, the first preset vehicle speed and the second preset vehicle speed, and the first preset value is used as the preset target deceleration. When the vehicle speed is less than the second preset vehicle speed, the preset target deceleration is the second preset value.

[0015] In one possible implementation, the first preset vehicle speed is greater than the second preset vehicle speed.

[0016] In one possible implementation, determining the first preset value based on the vehicle speed, the first preset vehicle speed, and the second preset vehicle speed includes: The first preset value a_target is calculated using the following formula: a_target = 0.9 * a_AEB * (V - V2) / (V1– V2) In the formula, a_AEB is the preset value of the AEB system, V is the vehicle speed, V1 is the first preset vehicle speed, and V2 is the second preset vehicle speed.

[0017] The present invention provides a method for suppressing nose-diving during near-stopping maneuvers in an AEB (Autonomous Emergency Braking) system. By real-time monitoring of the braking deceleration of the AEB system and the relative distance between the vehicle and the target object, the method calculates the actual time and distance from the current moment and position to the vehicle's complete stop. When it is determined that the vehicle is about to stop and certain conditions are met, the method actively and smoothly reduces braking pressure, thereby effectively mitigating the excessive nose-diving phenomenon caused by suspension and body inertia when the vehicle is nearing a complete stop. This invention significantly improves passenger comfort while ensuring AEB collision safety performance. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the head-nodding suppression method provided in an embodiment of the present invention. Detailed Implementation

[0019] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention. That is, the present invention is not limited to the described preferred embodiments, and the scope of the present invention is defined by the claims.

[0020] In the description of this invention, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance; those skilled in the art can understand the specific meaning of the above terms in this invention as appropriate.

[0021] Figure 1 A flowchart illustrating the head-nodding suppression method provided in an embodiment of the present invention is shown below. Figure 1 As shown, This invention provides a method for suppressing nose-diving in an AEB system when approaching a stop, comprising: Step S1: During the AEB system braking process, the vehicle speed and current braking deceleration are obtained in real time. Step S2: Calculate the predicted parking time and predicted parking distance based on vehicle speed and deceleration; In one possible implementation, accurate prediction of the stopping moment is the cornerstone of the entire system's safety. If the vehicle's braking position and stopping time cannot be predicted relatively accurately, the nose-dive suppression function may be missed or falsely triggered. Missed triggering reduces or eliminates the suppression effect, while false triggering compromises AEB braking safety.

[0022] Specifically, the vehicle speed (V) and current braking deceleration are acquired in real time, and based on these two core parameters, the parking time is predicted by calculation (e.g., T = V / a) and the parking distance is predicted by integration.

[0023] Step S3: When the predicted parking time reaches the preset parking time threshold or the predicted parking distance reaches the preset parking distance threshold, activate the head-nodding suppression function, collect the wheel speed and body acceleration of the vehicle in real time, and calculate the actual deceleration based on the wheel speed and body acceleration. In one possible implementation, a safety trigger mechanism acts as a "valve" to ensure safety. Intervention must be initiated at the very last moment after confirming that the danger has been largely eliminated and that stopping the vehicle is a foregone conclusion.

[0024] In this invention, "nose-diving" refers to the excessive downward pitching of the front of the vehicle due to suspension and body inertia as the vehicle approaches a complete stop. Once the nose-diving suppression function is activated, the maximum braking deceleration is no longer maintained, thus controlling the braking system to reduce braking pressure at a gradual incline. The vehicle comes to a smooth stop with lower and more stable braking force, avoiding nose-diving caused by sudden changes in braking force.

[0025] Specifically, this invention employs closed-loop feedback control, and the head-nodding suppression function cannot be a simple open-loop lookup table output. Instead, it uses feedback-based closed-loop control (such as PID, fuzzy control, model predictive control, MPC, etc.). Real-time acquisition of wheel speed and vehicle acceleration (from IMU) signals is used to calculate the actual deceleration, which is then compared with the target deceleration a_target. The controller algorithm dynamically adjusts the output braking torque command to eliminate tracking errors. The control algorithm used in this invention should possess a certain degree of robustness, capable of compensating for or adapting to nonlinear effects in the low-speed range. The corresponding controller (such as IBS, etc.) can achieve minute and rapid adjustments in braking deceleration.

[0026] Step S4: Dynamically adjust the braking torque output by the controller based on the actual deceleration and the preset target deceleration; The preset target deceleration is a dynamic value related to vehicle speed.

[0027] In one possible implementation, the error is calculated based on the difference between the actual deceleration and the preset target deceleration; the braking torque output by the controller is adjusted according to the PID algorithm and the error.

[0028] In one possible implementation, when the vehicle speed is less than a first preset speed, a first preset value is determined based on the vehicle speed, the first preset speed, and the second preset speed, and this first preset value is used as the preset target deceleration; when the vehicle speed is less than the second preset speed, the preset target deceleration is the second preset value. Wherein, the first preset speed is greater than the second preset speed. The second preset value is a pre-set fixed value.

[0029] In one possible implementation, the first preset value a_target is calculated according to the following formula: a_target = 0.9 * a_AEB * (V - V2) / (V1– V2) In the formula, a_AEB is the preset value of the AEB system, V is the vehicle speed, V1 is the first preset vehicle speed, and V2 is the second preset vehicle speed.

[0030] In one possible implementation, if any preset scenario is detected during the activation of the head-nodding suppression function, the head-nodding suppression function is exited, and the original high-priority braking request of AEB is restored or a corresponding strategy is executed according to the new situation.

[0031] The preset scenarios include: receiving a signal that the AEB system will actively exit, receiving a signal that the driver has pressed the accelerator pedal, receiving a signal that the driver has pressed the brake pedal and the requested braking force is greater than the force currently applied by the system, receiving a signal that the vehicle status is abnormal (such as wheel speed sensor failure, system communication failure), and other situations where the head-nodding suppression function must exit.

[0032] The present invention will be further described in detail below, with detailed implementation methods and specific operation processes provided. However, the scope of protection of the present invention is not limited to the following embodiments.

[0033] Set the preset calibration parameters, including: (1) Head-nodding suppression start threshold V_th_start = 6 km / h (2) Deceleration zero threshold V_th_end = 1 km / h (3) Deceleration threshold a_th = 3 m / s² (4) Target deceleration-vehicle speed mapping relationship f(V): A linear decay function is used.

[0034] (5) When V = 6 km / h, a_target = 0.9 * a_AEB (6) When V = 1 km / h, a_target = 0.1 m / s² (7) Linear interpolation of intermediate values: a_target = 0.9 * a_AEB * (V - 1) / (6 - 1), when V>1km / h; a_target = 0.1 m / s², when V ≤ 1 km / h.

[0035] Scenario: A vehicle is traveling at 40 km / h on a city road. A bicycle suddenly crosses the road about 25 meters ahead of the vehicle. The driver is distracted and fails to apply the brakes in time.

[0036] The braking process using the method of the present invention is shown in Table 1 below.

[0037] Table 1 Table 2 shows a comparison between the conventional AEB method and the method of the present invention.

[0038] Table 2 In addition, the following abnormal situation is pre-set: at t=1.8s (vehicle speed 4.0 km / h, head-dive suppression mode activated), the driver suddenly wakes up and forcefully presses the accelerator pedal. IBS detects the driver's accelerator override and reports it to the driver assistance domain controller. IPD immediately exits head-dive suppression mode. At the same time, depending on the driver's intention, it may disengage AEB braking or switch to driver-controlled acceleration. The entire process is completed within milliseconds, ensuring that driver intention takes precedence and guaranteeing safety.

[0039] The method for suppressing nose-diving in AEB systems nearing a stop provided by this invention has the following technical effects: 1) Precise intervention: It is accurately triggered when the vehicle speed drops to 6 km / h and is still effectively braking, which not only ensures the braking performance in the early stage, but also initiates comfort optimization at the right time.

[0040] 2) Intelligent planning: Through the pre-calibrated f(V) mapping relationship, an "ideal" braking curve is generated that smoothly decays from high deceleration to zero.

[0041] 3) Precise execution: Closed-loop control ensures that the actual braking force accurately tracks the target curve, overcoming the nonlinear effects in the low-speed region.

[0042] 4) Safe and reliable: A clear exit mechanism is set up to ensure that control can be regained immediately in the event of driver intervention or other situations.

[0043] 5) Significant results: Ultimately, while ensuring the safety performance of AEB, it effectively suppressed the nose-nodding phenomenon when approaching a stop, thus improving the driving experience.

[0044] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A nod-inhibition method for an AEB system at the time of approaching stop, characterized by, The application relates to an AEB system and a head nod suppression method thereof. During braking of the AEB system, the speed of the vehicle and the current deceleration are acquired in real time; a predicted stopping time and a predicted stopping distance are calculated according to the speed and the deceleration; when the predicted stopping time reaches a preset stopping time threshold or the predicted stopping distance reaches a preset stopping distance threshold, a head nod suppression function is activated, the wheel speed and the body acceleration of the vehicle are acquired in real time, and an actual deceleration is calculated according to the wheel speed and the body acceleration; a brake torque output by a controller is dynamically adjusted according to the actual deceleration and a preset target deceleration; the preset target deceleration is a dynamic value related to the speed.

2. The nod suppression method of claim 1, wherein, The application further relates to the following: during activation of the head nod suppression function, if any preset scene is detected, the head nod suppression function is exited.

3. The nod suppression method of claim 2, wherein, the preset scene includes receiving a signal of active exit of the AEB system.

4. The nod suppression method of claim 2, wherein, the preset scene further includes receiving a signal of the driver stepping on the accelerator pedal.

5. The nod suppression method of claim 2, wherein, the preset scene further includes receiving a signal of the driver stepping on the brake pedal and a requested brake force being greater than a current system applied force.

6. The nod suppression method of claim 2, wherein, the preset scene at least includes receiving a signal of abnormal vehicle state.

7. The nod suppression method of claim 1, wherein, the dynamically adjusting of the brake torque output by the controller according to the actual deceleration and the preset target deceleration includes: an error is calculated according to a difference between the actual deceleration and the preset target deceleration; a brake torque output by the controller is adjusted according to a PID algorithm and the error.

8. The nod suppression method of claim 1, wherein, the dynamically adjusting of the brake torque output by the controller according to the actual deceleration and the preset target deceleration includes: when the speed is less than a first preset speed, a first preset value is determined according to the speed, the first preset speed and a second preset speed, and the first preset value is taken as the preset target deceleration; when the speed is less than the second preset speed, the preset target deceleration is a second preset value.

9. The nod suppression method of claim 8, wherein, the first preset speed is greater than the second preset speed.

10. The nod suppression method of claim 8, wherein, the determining of the first preset value according to the speed, the first preset speed and the second preset speed includes: a first preset value a_target is calculated according to the following formula: a_target = 0.9 * a_AEB * (V - V2) / (V1–V2) wherein a_AEB is a preset value of the AEB system, V is the speed, V1 is the first preset speed and V2 is the second preset speed.

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