A two-layer automatic emergency braking control method

Abstract

The present invention relates to the technical field of safe driving, and specifically discloses a control method for two-layer automatic emergency braking. The driving mode of a main vehicle is extracted through an AEB two-stage braking algorithm, and whether a collision with an obstacle vehicle will occur is calculated according to the driving mode of the main vehicle. When the obstacle vehicle and the main vehicle are in a high-speed area, the main vehicle first performs partial braking until the main vehicle encounters an LPS critical line and turns. If the driver does not react, the AEB two-stage braking algorithm will use 100% full braking. When the obstacle vehicle and the main vehicle are in a low-speed area, the main vehicle encounters the LPS critical line and then the LPB critical line. The AEB two-stage braking algorithm will use 100% full braking. The method ensures anti-collision and a stable driving mode. Whether a collision will occur between the main vehicle and the obstacle vehicle is calculated through the AEB two-stage braking algorithm, and driving by performing partial braking or full braking can avoid collision accidents in different scenarios.

Description

Technical Field

[0001] The invention belongs to the technical field of safe driving, and in particular relates to a control method for two-layer automatic emergency braking. Background Art

[0002] Traffic accidents are one of the global concerns of the automotive industry. Over the past decade, major automotive OEMs, suppliers and R&D institutions have been focusing on safety systems that reduce driver errors and dangerous situations that can avoid crashes. Active safety systems alert drivers to imminent dangers and prevent accidents. These systems play an important role in reducing accidents and improving driving safety by monitoring the driver's performance. At the same time, they also provide travel comfort, as well as reducing traffic, optimizing fuel consumption and reducing pollution. The role of active safety systems has stimulated research in preventing the loss of life and property, especially in rear-end collisions, which account for an important position in accident statistics.

[0003] Currently, the general approach is to improve the efficiency of AEB performance, such as adaptive AEB systems based on fuzzy controllers. Factors such as driver attention (reaction time) or braking efficiency (maximum braking acceleration, as a combination of road and vehicle factors) have been calculated in fuzzy logic controllers. The relationship between braking force and slip speed has been studied by considering road conditions (such as friction and slope) and driving behavior.

[0004] Second, other studies have estimated in detail the collision time, collision distance and their integration in longitudinal safety control. These factors have been used as basic criteria for designing and developing AEB systems. Third, some researchers have studied the association of active and passive safety system integrity and interaction, such as finding the appropriate time for seat belt activation within the AEB system operation time, which has been discussed.

[0005] In the above methods, a single-stage braking method is usually used. As time goes by, due to the challenge of computational cost, the decision algorithm in the system becomes more complicated, making it impossible to guarantee collision avoidance and stable driving in different scenarios. Therefore, we need to propose a two-layer automatic emergency braking control method to solve the above problems and avoid collision accidents in different scenarios. Summary of the invention

[0006] The purpose of the present invention is to provide a two-level automatic emergency braking control method, which ensures anti-collision and stable driving modes. By calculating whether a main vehicle and an obstacle vehicle will collide through an AEB two-level braking algorithm, partial braking or full braking can be performed to avoid collision accidents in different scenarios, thereby solving the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A two-layer automatic emergency braking control method comprises the following steps:

[0009] S1. extracting the driving mode of the subject vehicle through the AEB two-stage braking algorithm, and calculating whether a collision with the obstacle vehicle will occur based on the driving mode of the subject vehicle, wherein the AEB two-stage braking algorithm includes the initiation of partial braking and full braking, and the driving mode includes an active driving mode, a normal driving mode, or a conservative driving mode;

[0010] S2: When the obstacle vehicle and the subject vehicle are in the high-speed area, the subject vehicle will first perform partial braking until the subject vehicle encounters the LPS critical line and turns. If the driver does not respond, the AEB two-level braking algorithm will use 100% full braking;

[0011] S3. When the obstacle vehicle and the main vehicle are in the low-speed area, the main vehicle meets the LPS critical line and then meets the LPB critical line, the AEB two-level braking algorithm will adopt 100% full braking.

[0012] Preferably, the AEB two-stage braking algorithm includes LPB calculation and LPS calculation, wherein LPB calculation is used to calculate the final point for braking, and LPS calculation is used to calculate the final point for steering. The position of the subject vehicle is calculated using x sub Indicates that the speed of the subject vehicle is expressed as V sub Indicates that the deceleration of the subject vehicle is D sub Indicates that the position of the obstacle vehicle is represented by x obs Indicates that the speed of the obstacle vehicle is V obs Indicates that the deceleration of the obstacle vehicle is D obs Indicates that the relative distance between the subject vehicle and the obstacle vehicle is: x rel =x obs -x sub , the relative speed between the subject vehicle and the obstacle vehicle is: V rel =V obs -V sub , the relative deceleration between the subject vehicle and the obstacle vehicle is: D rel =D obs -D sub .

[0013] Preferably, the equation for calculating LPB is as follows:

[0014]

[0015]

[0016] where d BTo brake at the last point, τ B D is the time delay for sufficient braking deceleration. max is the maximum deceleration of the subject vehicle, τ s is the turning delay, v diff is the subject vehicle speed.

[0017] Preferably, the equation for calculating LPS is as follows:

[0018]

[0019] d eva =v diff ·t eva

[0020] D max，rel =D max -D obs

[0021]

[0022] Among them, t eva is the required time, d eva To turn for the final point, a y，max is the maximum lateral acceleration, y eva To circumvent the required deviation offset.

[0023] Preferably, the AEB two-stage braking algorithm is applied to scenarios of non-accelerated obstacle vehicle movement and obstacle vehicle movement in a continuously decelerating manner, wherein in the non-accelerated obstacle vehicle movement scenario, if the obstacle vehicle moves at a constant speed, the main vehicle also moves at a constant speed, and there is no acceleration in the motion equation in the control model of the AEB two-stage braking algorithm; in the scenario of continuously decelerating obstacle vehicle movement, the obstacle vehicle moves at a constant decelerating speed, and there is acceleration in the motion equation in the control model of the AEB two-stage braking algorithm.

[0024] Preferably, the partial braking provides the driver of the subject vehicle with a predictive warning and appropriate measures, and provides the driver with sufficient time to avoid a collision through steering. If there is a vehicle behind the subject vehicle, the partial braking and the twitch following the partial braking will alert the rear driver to the imminent emergency risk.

[0025] Preferably, the warning levels of the AEB two-stage braking algorithm are defined as follows: safety level, warning start level, partial braking level, full braking level and most dangerous level. The decision-making of the AEB two-stage braking algorithm needs to be considered from the safety level of zero hazard to the most dangerous level.

[0026] Preferably, the AEB two-stage braking algorithm needs to be activated when used, and the activation conditions are as follows: in the safety level state, the three variables of the subject vehicle's position, speed and deceleration are all equal to 0; in the warning start level state, the three variables of the subject vehicle's position, speed and deceleration are all equal to 1; in the partial braking level and full braking level states, except when the subject vehicle overtakes an obstacle vehicle on a two-way road and encounters an obstacle vehicle in the opposite direction, the AEB two-stage braking algorithm is not activated, and the AEB two-stage braking algorithm is activated in other states, and the brakes are released after the vehicle stops completely.

[0027] Preferably, in step S2, there are two situations between the obstacle vehicle and the main vehicle in the high-speed area: one is that the main vehicle is not restricted by the LPB and LPS lines, and the driver avoids collision by braking or steering in addition to the speed; the other is that the main vehicle enters between the LPB and LPS lines, and the driver avoids collision by steering.

[0028] Preferably, in step S3, there are two situations when the obstacle vehicle and the subject vehicle are in the low-speed area: one is that the subject vehicle first passes through the LPS and then reaches the LPB, and the driver must apply the maximum braking force to avoid a collision; the other is that the subject vehicle passes through the boundary between the LPB and LPS, and except for the relative vehicle speed, neither braking nor steering can prevent the accident, and the driver applies a braking force of up to 100% to reduce the collision.

[0029] The two-layer automatic emergency braking control method proposed in the present invention has the following advantages compared with the prior art:

[0030] The present invention extracts the driving mode of the main vehicle through the AEB two-stage braking algorithm, and calculates whether a collision with the obstacle vehicle will occur according to the driving mode of the main vehicle. When the obstacle vehicle and the main vehicle are in a high-speed area, the main vehicle first performs partial braking until the main vehicle encounters the LPS critical line and turns. If the driver does not respond, the AEB two-stage braking algorithm will use 100% full braking. When the obstacle vehicle and the main vehicle are in a low-speed area, the main vehicle meets the LPS critical line and then meets the LPB critical line. The AEB two-stage braking algorithm will use 100% full braking. This method ensures collision avoidance and a stable driving mode. The AEB two-stage braking algorithm calculates whether the main vehicle and the obstacle vehicle will collide, and driving by partial braking or full braking can avoid collision accidents in different scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flowchart of the present invention;

[0032] Figure 2 A schematic diagram of the conceptual structure of the AEB two-stage braking algorithm of the present invention;

[0033] Figure 3 for Figure 2 The segmentation points of the four identified areas;

[0034] Figure 4 It is an overview diagram of the behavior of the decision algorithm of the present invention based on two different initial conditions;

[0035] Figure 5 It is a flowchart of the AEB pre-activation prerequisite of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] The present invention provides Figure 1 A two-layer automatic emergency braking control method shown includes the following steps:

[0038] S1. extracting the driving mode of the subject vehicle through the AEB two-stage braking algorithm, and calculating whether a collision with the obstacle vehicle will occur based on the driving mode of the subject vehicle, wherein the AEB two-stage braking algorithm includes the initiation of partial braking and full braking, and the driving mode includes an active driving mode, a normal driving mode, or a conservative driving mode;

[0039] The AEB two-stage braking algorithm includes LPB calculation and LPS calculation, wherein LPB calculation is used to calculate the last point to brake, and LPS calculation is used to calculate the last point to turn. The AEB two-stage braking algorithm will warn the driver of a possible collision. If the driver does not take corrective measures and a collision is about to occur, the AEB system will apply two-stage braking to avoid or mitigate the collision. The obstacle vehicle refers to a vehicle that may collide. In the state of the subject vehicle relative to the obstacle vehicle, the position of the subject vehicle is represented by x sub Indicates that the speed of the subject vehicle is expressed as V sub Indicates that the deceleration of the subject vehicle is D sub Indicates that the position of the obstacle vehicle is represented by x obs Indicates that the speed of the obstacle vehicle is V obs Indicates that the deceleration of the obstacle vehicle is D obs Indicates that the relative distance between the subject vehicle and the obstacle vehicle is: x rel =x obs -xsub , the relative speed between the subject vehicle and the obstacle vehicle is: V rel =V obs -V sub , the relative deceleration between the subject vehicle and the obstacle vehicle is: D rel =D obs -D sub .

[0040] The equation for the LPB calculation is as follows:

[0041]

[0042]

[0043] where d B To brake at the last point, τ B D is the time delay for sufficient braking deceleration. max is the maximum deceleration of the subject vehicle, τ s is the turning delay, v diff is the subject vehicle speed.

[0044] The equation for the LPS calculation is as follows:

[0045]

[0046] d eva =v diff ·t eva

[0047] D max，rel =D max -D obs

[0048]

[0049] Among them, t eva is the required time, d eva To turn for the final point, a y，max is the maximum lateral acceleration, y eva To circumvent the required deviation offset.

[0050] Last point braking (LPB) and last point steering (LPS) are two basic concepts of the AEB two-stage braking algorithm. In the above LPB calculation equation, d B Design algorithm, the above LPS calculation equation d eva The core algorithm of the design algorithm can be obtained from Figure 2 It is extracted from the simultaneous representation of LPB and LPS in the same coordinate system as shown. Figure 3 The table shown summarizes Figure 2The relative velocity at the intersection of LPB and LPS is called V ins , which is the key dividing point between high-speed and low-speed areas. Figure 2 Shown and Figure 3 In zone I mentioned in , the subject vehicle is not constrained by the LPB and LPS lines. Therefore, the driver can avoid the collision by braking or steering in addition to the relative speed. In zone II where the vehicle speed is a high speed area, the subject vehicle enters between the LPB and LPS lines. As a result, the collision cannot be avoided by braking, and the driver can only avoid the collision by steering maneuvers. In zone III where the vehicle speed is a low speed area, the subject vehicle first passes through the LPS and then reaches the LPB. Therefore, there is no time to avoid a collision by manipulating the steering gear, and the driver must apply the maximum braking force to avoid the collision. In zone IV, due to passing through the LPB and LPS boundary, neither braking nor steering can prevent the accident in addition to the relative vehicle speed. In this area, applying a braking force sufficient to 100% can only mitigate the collision. According to Figure 3 In the situations defined in the table, simultaneous longitudinal and lateral movements are possible. This means that the driver must use steering and braking maneuvers to avoid a collision. In such critical maneuvers, a very strong coupling between longitudinal and lateral dynamics occurs at several levels, in terms of dynamics, kinematics and tire forces, leading to vehicle instability. In such maneuvers, the tires enter the saturation zone and the tire dynamics leading to vehicle behavior will be completely nonlinear. It is important to note that the tension capacity of the tire is limited, meaning that if the longitudinal force on the tire increases, the maximum lateral force it can provide decreases and vice versa. The maximum longitudinal or lateral acceleration allowed at each moment will be very different.

[0051] The AEB two-stage braking algorithm is applied to scenarios of non-accelerated obstacle vehicle movement and obstacle vehicle movement with continuous deceleration. In the non-accelerated obstacle vehicle movement scenario, if the obstacle vehicle moves at a constant speed, the main vehicle also moves at a constant speed, and there is no acceleration in the motion equation in the control model of the AEB two-stage braking algorithm; in the scenario of continuous deceleration of the obstacle vehicle, the obstacle vehicle moves at a constant deceleration speed, and there is acceleration in the motion equation in the control model of the AEB two-stage braking algorithm.

[0052] The partial braking provides the driver of the subject vehicle with predictive warning and appropriate measures, and provides the driver with sufficient time to avoid a collision through steering. If there is a vehicle behind the subject vehicle, the driver behind will be reminded of the immediate emergency risk through partial braking and the twitch following partial braking.

[0053] The goal of two-stage braking (partial braking and full braking) is mainly to provide predictive warning and appropriate measures to the drivers of the subject vehicle under study and the following vehicle (if any). In other words, partial braking and the twitch that follows it will alert the driver to the imminent risk. In addition, partial braking provides the driver with enough time to avoid a collision by turning. However, the core and fundamental question in the design of two-stage braking proposed by the patented method is "What is the appropriate time and partial braking value?" The present application proposes a method to define a spatial variable selection scheme for these parameters. The concept and outline of the proposed algorithm in a constant speed scenario can be seen by Figure 2 The algorithm applies partial braking in the high-speed area within Region II until the traveling vehicle encounters the LPS line. This reduction in speed gives the driver time to escape by steering. If the driver does not react appropriately and faces the LPS line, the algorithm will apply 100% full braking because there is no time to avoid the collision by steering. In the low-speed area of ​​Region III, the situation is slightly different. The driver does not have time to escape the collision by steering. The subject vehicle encounters the LPS line and then the LPB line. Therefore, the algorithm should command 100% full braking as soon as the vehicle faces the LPB. In the proposed method, V ins (See Figure 4 ) is the dividing line between the high-speed and low-speed areas on the speed-distance coordinate diagram.

[0054] exist Figure 4 In , an overview of the decision algorithm with different initial conditions (Δ and Dp) is shown. It is obvious that inappropriate initial conditions can lead to collisions. An example of this problem can be found in Figure 2 However, in Figure 2 In curves ② and ③, the relative speed and relative distance converge to zero at the same time, and no accident occurs. From these descriptions, it can be seen that the main innovation of this patent may be the selection space algorithm that introduces Δ and Dp parameters to ensure collision avoidance. Figure 4The behavior of curve ③ in shows an ideal boundary trajectory. This means that if Δ and Dp are correctly selected according to the algorithm suggested by the patent, the subject vehicle will not collide. The patent mainly focuses on guiding the design of a two-stage braking algorithm for the AEB two-stage braking algorithm. In this way, the Δ parameter has been used as a criterion for determining the driving mode (active, normal or conservative driving mode). This mode category selection requires a detailed study of driver behavior, which is beyond the scope of the algorithm study of this patent. Therefore, only a general concept of this classification is provided here. When a smaller value of the Δ parameter (distance criterion) is selected, it is equivalent to selecting aggressive driving. In fact, drivers with a tendency to aggressive behavior and higher risks tend to brake as late as possible and brake closer to the obstacle vehicle, and brake with a higher intensity. This trend is in sharp contrast to the conservative driving type, which tends to keep a longer distance from the obstacle vehicle and avoid potential dangers with a lower braking intensity. Accordingly, the design of the AEB two-stage braking algorithm in this application can design the system according to the determined driving mode.

[0055] The warning levels of the AEB two-stage braking algorithm are defined as follows: safety level, warning start level, partial braking level, full braking level and most dangerous level. The decision-making of the AEB two-stage braking algorithm needs to be considered from the safety level of zero hazard to the most dangerous level.

[0056] Some assumptions were taken into account when implementing the algorithm. When steering to avoid a collision, a lane change operation is required, and the side line of the subject vehicle is assumed to be free of any obstacles. In addition, there is no vehicle behind the subject vehicle that is performing partial and full braking, otherwise this will lead to another accident. Therefore, before considering the AEB decision flowchart, it is necessary to consider one of the above possible scenarios that may undermine the implementation of the decision algorithm. In addition, in some cases, the absolute speeds of both vehicles are non-zero and equal, so the relative speed is close to zero. From the perspective of calculating the time to collision, there is no danger. However, if the relative distance between the two vehicles is quite small, this situation will have a high probability of an accident. Once the obstacle vehicle brakes slightly, the situation becomes unstable and the probability of collision increases significantly. Therefore, the decision algorithm should take into account the time interval criteria and the time to collision to prevent collisions in these situations. Figure 5In the figure, a flowchart under the pre-activation condition of the AEB two-stage braking algorithm is described. Before activating the system, some safety measures and conditions should be considered to be strengthened at the implementation stage of the vehicle level. In the figure, IGN is the ignition. When IGN is turned off, the vehicle is at a safety level of zero accidents. After the subject vehicle receives the ignition signal, the subject vehicle IGN is turned on, the AEB switch is in the off state, and the subject vehicle is at the warning start level. When the AEB two-stage braking algorithm receives the start signal, the AEB two-stage braking algorithm is started, and the subject vehicle performs partial braking. At this time, it is at the partial braking level. When the full braking receives any one or more signals of ESC system start, drive mode gear start, sensor target detection and subject vehicle speed at 10 or 15km / h, full braking is performed. At this time, the subject vehicle is at the full braking level.

[0057] The AEB two-stage braking algorithm needs to be activated when used, and the activation conditions are as follows: in the safety level state, the three variables of the subject vehicle's position, speed and deceleration are all equal to 0; in the warning start level state, the three variables of the subject vehicle's position, speed and deceleration are all equal to 1; in the partial braking level and full braking level states, except when the subject vehicle overtakes an obstacle vehicle on a two-way road and encounters an obstacle vehicle in the opposite direction, the AEB two-stage braking algorithm is not activated. In other states, the AEB two-stage braking algorithm is activated and the brakes are released after the vehicle stops completely.

[0058] S2. When the obstacle vehicle and the main vehicle are in the high-speed area, the main vehicle will first perform partial braking until the main vehicle encounters the LPS critical line and turns. If the driver does not respond, the AEB two-level braking algorithm will use 100% full braking; there are two situations between the obstacle vehicle and the main vehicle in the high-speed area: one is that the main vehicle is not restricted by the LPB and LPS lines, and the driver avoids collision by braking or turning except for the relative speed; the other situation is that the main vehicle enters between the LPB and LPS lines, and the driver avoids collision by turning.

[0059] S3. When the obstacle vehicle and the main vehicle are in the low-speed area, the main vehicle meets the LPS critical line and then the LPB critical line, the AEB two-level braking algorithm will use 100% full braking; there are two situations when the obstacle vehicle and the main vehicle are in the low-speed area: one is that the main vehicle first passes through the LPS and then reaches the LPB, and the driver must apply the maximum braking force to avoid a collision; the other is that the main vehicle passes through the LPB and LPS boundaries. Except for the relative vehicle speed, braking and steering cannot prevent the accident, and the driver applies a full 100% braking force to reduce the collision.

[0060] In summary, the AEB two-stage braking algorithm extracts the driving mode of the main vehicle, and calculates whether a collision with the obstacle vehicle will occur based on the driving mode of the main vehicle. When the obstacle vehicle and the main vehicle are in the high-speed area, the main vehicle first performs partial braking until the main vehicle encounters the LPS critical line and turns. If the driver does not respond, the AEB two-stage braking algorithm will use 100% full braking. When the obstacle vehicle and the main vehicle are in the low-speed area, the main vehicle meets the LPS critical line and then meets the LPB critical line. The AEB two-stage braking algorithm will use 100% full braking. This method ensures collision avoidance and a stable driving mode. The AEB two-stage braking algorithm calculates whether the main vehicle and the obstacle vehicle will collide, and driving by partial braking or full braking can avoid collision accidents in different scenarios.

[0061] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A two-layer automatic emergency braking control method, characterized in that: The steps include: S1. extracting the driving mode of the subject vehicle through the AEB two-stage braking algorithm, and calculating whether a collision with the obstacle vehicle will occur based on the driving mode of the subject vehicle, wherein the AEB two-stage braking algorithm includes the initiation of partial braking and full braking, and the driving mode includes an active driving mode, a normal driving mode, or a conservative driving mode; S2: When the obstacle vehicle and the subject vehicle are in the high-speed area, the subject vehicle will first perform partial braking until the subject vehicle encounters the LPS critical line and turns. If the driver does not respond, the AEB two-level braking algorithm will use 100% full braking; S3: When the obstacle vehicle and the main vehicle are in the low-speed area, the main vehicle meets the LPS critical line and then the LPB critical line, the AEB two-stage braking algorithm will use 100% full braking; The AEB two-stage braking algorithm includes LPB calculation and LPS calculation, wherein LPB calculation is used to calculate the final point for braking, and LPS calculation is used to calculate the final point for steering. The position of the subject vehicle is calculated using x sub Indicates that the speed of the subject vehicle is expressed as V sub Indicates that the deceleration of the subject vehicle is D sub Indicates that the position of the obstacle vehicle is represented by x obs Indicates that the speed of the obstacle vehicle is V obs Indicates that the deceleration of the obstacle vehicle is D obs Indicates that the relative distance between the subject vehicle and the obstacle vehicle is: x rel =x obs -x sub , the relative speed between the subject vehicle and the obstacle vehicle is: V rel =V obs -V sub , the relative deceleration between the subject vehicle and the obstacle vehicle is: D rel =D obs -D sub ; The equation for the LPB calculation is as follows: where d B To brake at the last point, τ B D is the time delay for sufficient braking deceleration. max is the maximum deceleration of the subject vehicle, τ s is the turning delay, v diff is the subject vehicle speed; The equation for the LPS calculation is as follows: d eva =v diff .t eva D max，rel =D max -D obs Among them, t eva is the required time, d eva To turn for the final point, a y，max is the maximum lateral acceleration, y eva To circumvent the required deviation offset.

2. A two-layer automatic emergency braking control method according to claim 1, characterized in that: The AEB two-stage braking algorithm is applied to scenarios of non-accelerated obstacle vehicle movement and obstacle vehicle movement with continuous deceleration. In the non-accelerated obstacle vehicle movement scenario, if the obstacle vehicle moves at a constant speed, the main vehicle also moves at a constant speed, and there is no acceleration in the motion equation in the control model of the AEB two-stage braking algorithm; in the scenario of continuous deceleration of the obstacle vehicle, the obstacle vehicle moves at a constant deceleration speed, and there is acceleration in the motion equation in the control model of the AEB two-stage braking algorithm.

3. A two-layer automatic emergency braking control method according to claim 2, characterized in that: The partial braking provides the driver of the subject vehicle with predictive warning and appropriate measures, and provides the driver with sufficient time to avoid a collision through steering. If there is a vehicle behind the subject vehicle, the driver behind will be reminded of the immediate emergency risk through partial braking and the twitch following partial braking.

4. A two-layer automatic emergency braking control method according to claim 3, characterized in that: The warning levels of the AEB two-stage braking algorithm are defined as follows: safety level, warning start level, partial braking level, full braking level and most dangerous level. The decision-making of the AEB two-stage braking algorithm needs to be considered from the safety level of zero hazard to the most dangerous level.

5. A two-layer automatic emergency braking control method according to claim 4, characterized in that: The AEB two-stage braking algorithm needs to be activated when used, and the activation conditions are as follows: in the safety level state, the three variables of the subject vehicle's position, speed and deceleration are all equal to 0; in the warning start level state, the three variables of the subject vehicle's position, speed and deceleration are all equal to 1; in the partial braking level and full braking level states, except when the subject vehicle overtakes an obstacle vehicle on a two-way road and encounters an obstacle vehicle in the opposite direction, the AEB two-stage braking algorithm is not activated. In other states, the AEB two-stage braking algorithm is activated and the brakes are released after the vehicle stops completely.

6. A two-layer automatic emergency braking control method according to claim 5, characterized in that: In step S2, there are two situations when the obstacle vehicle and the main vehicle are in the high-speed area: one is that the main vehicle is not restricted by the LPB and LPS lines, and the driver avoids collision by braking or steering in addition to speed; the other is that the main vehicle enters between the LPB and LPS lines, and the driver avoids collision by steering.

7. A two-layer automatic emergency braking control method according to claim 6, characterized in that: In step S3, there are two situations when the obstacle vehicle and the subject vehicle are in the low-speed area: one is that the subject vehicle first passes through the LPS and then reaches the LPB, and the driver must apply the maximum braking force to avoid a collision; the other is that the subject vehicle passes through the boundary between the LPB and LPS, and except for the relative vehicle speed, braking and steering cannot prevent the accident, and the driver applies a full 100% braking force to reduce the collision.

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